WO2025226576A1 - Processes for producing isobutylene and isobutylene-based polymers - Google Patents

Abstract

The present disclosure relates to processes for producing isobutylene and isobutylene- based polymers. In some embodiments, a process includes dehydrating a bio-based isobutanol in an isobutanol dehydration unit to form a butenes composition. The process includes providing the butenes composition to one or more of an acid extraction unit or a butyl ether formation unit.

Description

PROCESSES FOR PRODUCING ISOBUTYLENE AND ISOBUTYLENE-BASED POLYMERS CROSS-REFERENCE TO RELATED APPLICATION [0001] This application claims the benefit of U.S. Provisional Application 63/638,773 filed APRIL 25, 2024 entitled PROCESSES FOR PRODUCING ISOBUTYLENE AND ISOBUTYLENE-BASED POLYMERS, the entirety of which is incorporated by reference herein. FIELD [0002] The present disclosure relates to processes for producing isobutylene and isobutylene- based polymers. BACKGROUND [0003] There is strong interest in using bio-based feedstocks to reduce the carbon intensity of chemical products, including polymers. Tire manufacturers in particular are interested in sustainable raw materials, including butyl rubber for tire innerliners and innertubes. A butyl rubber backbone polymer is typically comprised of about 98 wt% isobutylene. However, a barrier to using bio-based isobutylene to produce butyl rubber is that the bio-based isobutylene has low purity making it unsuitable for direct use in the synthesis of butyl polymers. [0004] For example, isobutanol can be produced by fermentation of sugars or biomass by microorganisms, thermochemical conversion of biomass, or photosynthesis by specialized plants or microorganisms. U.S. Patent No. 8,373,012 teaches that the dehydration of isobutanol produces a mixture of C4 alkenes, including isobutylene, butene-1, and cis- and trans-butene-2. Under ideal conditions, isobutylene purity may approach 99%. For the specific example of dehydrating isobutanol at 280°C using a ɣ-alumina catalyst under optimal conditions, the isobutylene purity was only 97%. These purity levels are too low to directly support production of high molecular weight polymers, such as butyl polymers (IIR, BIIR, CIIR, BIMSM) and medium- to high-MW polyisobutylene. Polymerization-grade isobutylene generally has a purity >99.5%. [0005] U.S. Patent No. 9,126,877 discloses a purification process to remove butenes from bio- based isobutylene for the production of isobutylene-based polymers. The process entails contacting the C4 alkene mixture from the isobutanol dehydration process with an adsorbent microporous material having an effective pore opening of 5 Å to 5.4 Å for about 6 to about 24 hours in an enclosed container. This process is said to selectively adsorb the linear butenes to the microporous material. The isobutylene can then be isolated from the microporous material. However, the long contact time for this purification process makes it commercially impractical in addition to use of prohibitively large adsorbent beds to support commercial-scale production rates of isobutylene-based polymers. In addition, these adsorbent beds oligomerize monomers into dimers and trimers. [0006] In addition, microorganisms exist that can directly produce isobutylene from biomass. The impurities are easier to remove by distillation and other separation techniques to yield polymerization-grade isobutylene. However, development of fermentation methods, for example, involve metabolic pathways involving unusual enzymatic conversions and large amounts of biowaste. In addition, the efficiency of biomass conversion to isobutylene is currently much lower than conversion to isobutanol, has limited scale-up, and results in high cost compared to alternatives. [0007] There remains a need to develop practical processes to produce bio-based isobutylene that is pure enough for the production of high molecular weight polymers and is scalable as an industrial sized process for bio-based isobutylene. [0008] References for citing in an Information Disclosure Statement (37 C.F.R.1.97(h)): U.S. 9,266,791; U.S. 5,420,360; U.S. 5,108,719; U.S. 4,307,254; U.S. 5,078,751; U.S. 7,102,037; U.S. 4,691,073; U.S. 2015/0329877; U.S. 8,450,543; G.B. 850,415; CA 515493; CA 791196; U.S. 2016/0032326; U.S.9,126,877; U.S.10,513,475; U.S.8,373,012. SUMMARY [0009] The present disclosure relates to processes for producing isobutylene and isobutylene- based polymers. [0010] In some embodiments, a process includes dehydrating a bio-based isobutanol in an isobutanol dehydration unit to form a butenes composition. The process includes providing the butenes composition to one or more of an acid extraction unit or a butyl ether formation unit. [0011] In some embodiments, a process includes providing a bio-based isobutanol to an alcohol dehydration unit to form a butenes composition. The process includes providing the butenes composition to an acid extraction unit to form a tert-butanol product. The process includes providing the tert-butanol product to the alcohol dehydration unit to form an isobutylene product that is 99 wt% or greater isobutylene. [0012] In some embodiments, a process includes providing a bio-based isobutanol to an alcohol dehydration unit to form a butenes composition. The process includes providing the butenes composition to a butyl ether formation unit to form a butyl ether product (e.g. MTBE). The process includes providing the butyl ether product to a butyl ether decomposition unit to form an isobutylene product that is 99 wt% or greater isobutylene. [0013] In some embodiments, a process includes providing a bio-based isobutanol to a catalytic cracking or steam cracking unit at cracking conditions to form a butenes composition. The cracking conditions comprise a temperature of about 450 ^oC to about 650 ^oC and a pressure of about 250 kPa to about 400 kPa. The process includes providing the butenes composition to an acid extraction unit to form a tert-butanol product. The process includes providing the tert-butanol product to an alcohol dehydration unit to form an isobutylene product that is 99 wt% or greater isobutylene. Alternatively, certified chain of custody mass attributions methods (e.g. ISCC PLUS certification) can be used to tie the use of bio-based isobutanol and, optionally, other bio-based alcohols (e.g. ethanol) as cracker feeds to isobutylene products and isobutylene-based polymers derived therefrom. [0014] In some embodiments, a process includes providing a bio-based isobutanol to a catalytic cracking or steam cracking unit at cracking conditions to form a butenes composition. The cracking conditions comprise a temperature of about 450 ^oC to about 650 ^oC and a pressure of about 250 kPa to about 400 kPa. The process includes providing the butenes composition to a butyl ether formation unit to form a butyl ether product (e.g. MTBE). The process includes providing the butyl ether product to a butyl ether decomposition unit to form an isobutylene product that is 99 wt% or greater isobutylene. Alternatively, certified chain of custody mass attributions methods (e.g. ISCC PLUS certification) can be used to tie the use of bio-based isobutanol and, optionally, other bio-based alcohols (e.g. ethanol), as cracker feeds to isobutylene products and isobutylene-based polymers derived therefrom. [0015] In some embodiments, a butyl rubber includes about 85 wt% to about 99.5 wt% bio-based isobutylene units and about 0.5 wt% to about 15 wt% isoprene units. The butyl rubber has a weight average molecular weight (Mw), as determined by gel permeation chromatography (GPC), of about 380 kDa to about 2,000 kDa. BRIEF DESCRIPTION OF THE FIGURES [0016] So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to aspects, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical aspects of this present disclosure and are therefore not to be considered limiting of its scope, for the present disclosure may admit to other equally effective aspects. [0017] FIG. 1 is a diagram illustrating an isobutylene production system, according to some embodiments. [0018] To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. The figures are not drawn to scale and may be simplified for clarity. It is contemplated that elements and features of one aspect may be beneficially incorporated in other aspects without further recitation. DETAILED DESCRIPTION [0019] The present application relates to processes for producing isobutylene and isobutylene- based polymers. Processes of the present disclosure can produce bio-based isobutylene that is pure enough (e.g., greater than 99.5%) for the production of high molecular weight polymers (such as butyl rubber) and is scalable as industrial sized processes for bio-based isobutylene. In fact, processes of the present disclosure can provide butyl rubbers made entirely of bio-based monomers – from highly pure isobutylene and optionally the isoprene comonomer (which can be made from the highly pure isobutylene via a Prins reaction). Indeed, bio-based butyl rubbers can be made that are indistinguishable from fossil fuel-based butyl rubbers. [0020] When introducing elements of various embodiments of the present disclosure, the articles “a,” “an,” and “the” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. Additionally, it should be understood that references to “one embodiment” or “an embodiment” of the present disclosure are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. [0021] As used herein, the term "isoolefin" refers to any olefin monomer having at least one carbon having two substitutions on that carbon. As used herein, the term "multiolefin" refers to any monomer having two (e.g., "diolefin") or more double bonds (e.g., "triolefin," etc.). In some embodiments, the multiolefin is any monomer comprising at least two conjugated double bonds, such as a conjugated diene (like isoprene). [0022] The phrases "isobutylene based elastomer" or "isobutylene based polymer" or “butyl rubber” refer to elastomers or polymers comprising at least 70 mol % isobutylene units from isobutylene. Further, the term "butyl" is used interchangeably with the phrase "isobutylene based" herein. [0023] FIG.1 is a diagram illustrating an isobutylene production system 100. As shown in FIG. 1, an isobutanol production unit 102 produces isobutanol that is then sent via line 104 to isobutanol dehydration unit 106. Byproducts (such as other butenes and unreacted isobutanol) can be provided via line 114 as a first portion of butene stream of line 114 (via line 118) to butyl ether unit 120 to provide reaction of isobutylene to form a butyl ether, such as methyl tert-butyl ether. Butyl ether product from butyl ether unit 120 can be provided via line 122 to butyl ether decomposition unit 124 to yield highly pure isobutylene (e.g., 99% or greater isobutylene). A second portion of byproducts butene stream of line 114 can be provided via line 126 to the acid extraction unit 110 where isobutylene content in the butenes portion is formed into tert-butanol and separated from the remainder of the unreacted butenes portion. The tert-butanol is provided via line 128 to tert-butanol dehydration unit 130 to yield highly pure isobutylene. [0024] Additionally or alternatively, as also shown in FIG. 1, isobutanol from isobutanol production unit 102 can be provided via line 132 to the tert-butanol dehydration unit 130 to provide dehydration of isobutanol (isobutylene formation) to yield a butene stream that can be provided via line 134 to the acid extraction unit 110 for acid extraction of the butene stream followed by subsequent tert-butanol dehydration (in tert-butanol dehydration unit 130) of the acid-extracted butene stream to form additional highly pure isobutylene. [0025] Additionally or alternatively, as also shown in FIG. 1, isobutanol from isobutanol production unit 102 can be provided via line 136 to a catalyst cracking or steam cracking unit 138 to provide a butene stream provided via line 140 to acid extraction unit 110 for acid extraction of the butene stream of line 140 and subsequent tert-butanol dehydration (in tert-butanol dehydration unit 130) of the acid-extracted butene stream to form additional highly pure isobutylene. [0026] Additionally or alternatively, butene stream of line 140 from the cracking unit 138 can be directed to unit 120 (not shown). Conversion of isobutanol to isobutylene by the cracking unit may be quite low, e.g., feed to 138 can mainly be done for mass attribution of bio-content to isobutylene products from units 124 or 130 via ISCC PLUS Certification. Because of this, an additional "bio- based feedstock" stream (like bio-ethanol) can be separately provided (not shown) to cracker 138. [0027] Highly pure isobutylene of the present disclosure can be used to form butyl rubber. Butyl rubber of the present disclosure can provide sustainability credits, e.g., as verified by mass attribution such as International Sustainability & Carbon Certification (ISCC) (based on the process of making the butyl rubber and monomers thereof). In particular, ISCC has been designed to trace the flow of materials through a complex value chain. Since chemically recycled or bio-based feedstocks are typically blended in the manufacturing complex, physical segregation of recycled content is often practically and economically very difficult. A mass balance approach makes it possible to track the amount and sustainability characteristics of circular and/or bio-based material in the value chain and attribute it based on verifiable processes used to make the polymers. [0028] Although FIG.1 is illustrated with the various units (e.g., unit 102) are connected via one or more lines (e.g., line 114), it is to be understood that lines are optional and a product from one unit (e.g., isobutanol of unit 102) can be transported by various other methods, such as by transportation in a vehicle, to the various other units (e.g., to isobutanol dehydration unit 106). The product of unit 102 or 106 can also be blended with other bio-based or petroleum streams, such as tert-butanol or Raffinate-1, before further processing. Production of Isobutanol [0029] Isobutanol for processes of the present disclosure can be obtained commercially or can be produced (e.g., in isobutanol production unit 102 from biomass). The term “formation of isobutanol from biomass” includes any suitable combination of methods including fermentation, thermochemical (e.g., Fischer-Tropsch), photosynthesis, etc. of a biomass. Bio-based alcohols (e.g., isobutanol) can be prepared from biomass by the same method, or by different methods, or portions of the isobutanol can be prepared by a combination of different methods. [0030] When bio-based isobutanol is formed by fermentation, the biomass feedstock for the fermentation process can be any suitable fermentable feedstock known in the art, for example sugars derived from agricultural crops such as sugarcane, corn, etc. In some embodiments, formation of isobutanol from biomass is performed by obtaining a bio-based isobutanol from fermentation of sugar(s). In some embodiments, the fermentable feedstock can be prepared by the hydrolysis of biomass, for example lignocellulosic biomass (e.g., wood, corn stover, switchgrass, herbiage plants, ocean biomass; etc.). The lignocellulosic biomass can be converted to fermentable sugars by various processes known in the art, for example acid hydrolysis, alkaline hydrolysis, enzymatic hydrolysis, or combinations thereof. In such processes, the carbohydrate component of the biomass (e.g., cellulose and hemicellulose) are broken down by hydrolysis to their constituent sugars, which can then be fermented by suitable microorganisms as described herein to provide bio-based isobutanol. [0031] Typically, wood-based plants comprise about 40-50% cellulose, 20-30% hemicellulose, and 20-28% lignin (wt% in dry wood), with minor amounts of minerals and other organic extractives. The cellulose component is a polysaccharide comprising glucose monomers coupled with β-1,4- glycoside linkages. The hemicellulose component is also a polysaccharide, but comprising various five-carbon sugars (usually xylose and arabinose), six-carbon sugars (galactose, glucose, and mannose), and 4-O-methyl glucuronic acid and galacturonic acid residues. The cellulose and hemicellulose components are hydrolyzed to fermentable five- and six-carbon sugars which can then be used as a feedstock for the fermentation as described herein. Residual carbon compounds, lignin (a highly branched polyphenolic substance), and organic extractives (e.g., waxes, oils, alkaloids, proteins, resins, terpenes, etc.) can be separated from the sugars at various stages of the hydrolysis process and utilized in various ways, for example, burned has a fuel to provide energy/heat for the fermentation process and/or for subsequent processes (e.g., dehydration, oligomerization, dehydrogenation, etc.). [0032] In at least one embodiment, isobutanol is formed by one or more fermentation steps as described herein. Any suitable microorganism can be used to prepare isobutanol. Butanols (e.g., isobutanol) can be produced, for example, by the microorganisms as described in U.S. Patent Publication Nos. 2007/0092957, 2008/0138870, 2008/0182308, 2007/0259410, 2007/0292927, 2007/0259411, 2008/0124774, 2008/0261230, 2009/0226991, 2009/0226990, 2009/0171129, 2009/0215137, 2009/0155869, 2009/0155869 and 2008/02745425, etc. [0033] Isobutanol can be produced in one or more fermentors under conditions for the production of isobutanol (e.g., using microorganisms which produce high yields of isobutanol, a fermentable feedstock with suitable nutrients optimal for isobutanol-producing microorganisms, temperature conditions and isobutanol recovery unit operations optimized for isobutanol production, etc.). In some embodiments, isobutanol is produced in an ethanol fermentation plant retrofitted for the production of isobutanol, for example as described in U.S. Patent No.8,101,808. [0034] In at least one embodiment, the retrofitted ethanol plant includes an optional pretreatment unit, multiple fermentation units, and a beer still to produce isobutanol. The isobutanol is produced by optionally pretreating a feedstock (e.g., ground corn) to form fermentable sugars in the pretreatment unit. A suitable microorganism, as described herein, is cultured in a fermentation medium comprising the fermentable sugars in one or more of the fermentation units to produce isobutanol. The isobutanol can be recovered from the fermentation medium as described herein, and as described in U.S. Patent No.8,101,808. [0035] Bio-based butanols can also be prepared using various other methods such as conversion of biomass by thermochemical methods, for example by gasification of biomass to synthesis gas followed by catalytic conversion of the synthesis gas to alcohols in the presence of a catalyst containing elements such as copper, aluminum, chromium, manganese, iron, cobalt, or other metals and alkali metals such as lithium, sodium, and/or potassium (Energy and Fuels 2008 (22) 814-839). The various alcohols, including butanols, can be separated from the mixture by distillation and used to prepare bio-based butenes and other compounds derived from bio-based butenes. Alcohols other than ethanol and isobutanol can be recovered and utilized as feedstocks for other processes, burned as fuel or used as a fuel additive, etc. [0036] Alternatively, butanols can be prepared photosynthetically, e.g., using cyanobacteria or algae engineered to produce isobutanol and/or other alcohols (e.g., using Synechococcus elongatus PCC7942 and Synechocystis PCC6803; see Angermayr et al., Energy Biotechnology with Cyanobacteria, Curr Opin Biotech 2009 (20) 257-261; Atsumi and Liao, Nature Biotechnology 2009 (27) 1177-1182; and Dexter et al., Energy Environ. Sci.2009 (2), 857-864, and references cited in each of these references). When produced photosynthetically, the “feedstock” for producing the resulting bio-based alcohols is light, water and CO₂ provided to the photosynthetic organism (e.g., cyanobacteria or algae). [0037] Higher alcohols other than butanols or pentanols produced during fermentation (or other processes as described herein for preparing butanols) may be removed from the butanol(s) prior to carrying out subsequent operations (e.g., dehydration). The separation of these higher alcohols from the butanol(s) (e.g., isobutanol) can be effected using known methods such as distillation, extraction, etc. Isolation of Alcohols (Isobutanol) from Fermentation [0038] When the alcohols such as isobutanol are prepared by fermentation, the alcohol (e.g., isobutanol) can be removed from the fermentor by various methods, for example fractional distillation, solvent extraction (e.g., with a bio-based solvent such as bio-based oligomerized hydrocarbons, bio-based hydrogenated hydrocarbons, bio-based aromatic hydrocarbons, etc. which may be prepared as described in U.S. patent application Ser. No. 12/986,918), gas stripping, adsorption, pervaporation, etc., or by combinations of such methods, prior to dehydration. In certain embodiments, the alcohol is removed from the fermentor in the vapor phase under reduced pressure (e.g., as an azeotrope with water as described in U.S. Patent No. 8,101,808). In some such embodiments, the fermentor itself is operated under reduced pressure without the application of additional heat (other than that used to provide optimal fermentation conditions for the microorganism) and without the use of distillation equipment, and the produced alcohol (e.g., isobutanol) is removed as an aqueous vapor (or azeotrope) from the fermentor. In either such embodiments, the fermentor is operated under approximately atmospheric pressure or slightly elevated pressure (e.g., due to the evolution of gases such as CO₂ during fermentation) and a portion of the feedstock containing the alcohol (e.g., isobutanol) is continuously recycled through a flash tank operated under reduced pressure, whereby the alcohol (e.g., isobutanol) is removed from the headspace of the flash tank as an aqueous vapor or water azeotrope. These latter embodiments have the advantage of providing for separation of the alcohol (e.g., isobutanol) without the use of energy intensive or equipment intensive unit operations (e.g., distillation), as well as continuously removing a metabolic, by-product of the fermentation, thereby improving the productivity of the fermentation process. The resulting wet alcohol (e.g., isobutanol) can be dried and then dehydrated, or dehydrated wet (as described herein), then subsequently dried. [0039] The production of bio-based isobutanol by fermentation of carbohydrates typically co- produces small (<5% w/w) amounts of 3-methyl-1-butanol and 2-methyl-1-butanol and much lower levels of other alcohols. One mechanism by which these by-products form is the use of intermediates in hydrophobic amino acid biosynthesis by the isobutanol-producing metabolic pathway that is engineered into the host microorganism. The genes involved with the production of intermediates that are converted to 3-methyl-1-butanol and 2-methyl-1-butanol are known and can be manipulated to control the amount of 3-methyl-1-butanol produced in these fermentations (see, e.g., Connor and Liao, Appl Environ Microbiol 2008 (74) 5769). Removal of these genes can decrease 3-methyl-1- butanol and/or 2-methyl-1-butanol production to negligible amounts, while overexpression of these genes can be tuned to produce any amount of 3-methyl-1-butanol in a typical fermentation. Alternatively, the thermochemical conversion of biomass to mixed alcohols produces both isobutanol and these pentanols. Accordingly, when biomass is converted thermochemically, the relative amounts of these alcohols can be adjusted using specific catalysts and/or reaction conditions (e.g., temperature, pressure, etc.). Dehydration of Isobutanol to Butenes [0040] Alcohols (e.g., butanol(s)) obtained (e.g., in isobutanol production unit 102) by biochemical or thermochemical production routes can be converted into their corresponding olefins (e.g., in isobutanol dehydration unit 106 or tert-butyl dehydration unit 130) by reacting the alcohols over a dehydration catalyst under appropriate conditions. Typical dehydration catalysts that convert alcohols such as isobutanol into butene(s) include various acid treated and untreated alumina (e.g., γ- alumina) and silica catalysts and clays including zeolites (e.g., β-type zeolites, ZSM-5 or Y-type zeolites, fluoride-treated β-zeolite catalysts, fluoride-treated clay catalysts, etc.), sulfonic acid resins (e.g., sulfonated styrenic resins such as Amberlyst® 15), strong acids such as phosphoric acid and sulfuric acid, Lewis acids such boron trifluoride and aluminum trichloride, and many different types of metal salts including, metal oxides (e.g., zirconium oxide or titanium dioxide) and metal chlorides (e.g., Latshaw B E, Dehydration of Isobutanol to Isobutylene in a Slurry Reactor, Department of Energy Topical Report, February 1994). The dehydration reaction typically occurs over a heterogeneous catalyst such as γ-alumina at moderate temperatures (e.g., about 250-350° C.) and low pressures (e.g., 0-100 psig). In some embodiments, unit 106 utilizes biochemical processes for the dehydration, such as those described in van Leeuwen et al., "Fermentative production of isobutene", Appl. Microbiol. Biotechnol. 2012; 93 (4): 1377-1387. [0041] Dehydration reactions can be carried out in both gas and liquid phases with both heterogeneous and homogeneous catalyst systems in many different reactor configurations. Typically, the catalysts used are stable to the water that is generated by the reaction. The water is usually removed from the reaction zone with the product. The resulting alkene(s) either exit the reactor in the gas or liquid phase, depending upon the reactor conditions, and may be separated and/or purified downstream or further converted in the reactor to other compounds (e.g., isomers, dimers, trimers, etc.) as described herein. The water generated by the dehydration reaction may exit the reactor with unreacted alcohol and alkene product(s) and may be separated by distillation or phase separation. [0042] Because water is generated in large quantities in the dehydration step, the dehydration catalysts used are generally tolerant to water and a process for removing the water from substrate and product may be part of any process that contains a dehydration step. For this reason, it is possible to use wet (e.g., up to about 95% or 98% water by weight) alcohol as a substrate for a dehydration reaction, then remove water introduced with alcohol in the reactor feed stream with the water generated by the dehydration reaction during or after the dehydration reaction (e.g., using a zeolite catalyst such as those described U.S. Pat. Nos. 4,698,452 and 4,873,392). Additionally, neutral alumina and zeolites can dehydrate alcohols to alkenes but generally at higher temperatures and pressures than the acidic versions of these catalysts. In certain embodiments, the alkene(s) produced in the dehydration reaction are isolated after the dehydration step, before being used as feedstocks for subsequent processes such as acid extraction unit 110. [0043] When 1-butanol, 2-butanol, or isobutanol are dehydrated, a mixture of four C4 olefins— 1-butene, cis-2-butene, trans-2-butene, and isobutylene — can be formed (e.g., line 118 or line 126). The exact concentration in a product stream of each butene isomer is determined by the thermodynamics of formation of each isomer. Accordingly, the reaction conditions and catalysts used can be manipulated to affect the distribution of butene isomers in the product stream. Thus, one can obtain butene mixtures enriched in a particular isomer. However, while production of a single butene isomer by dehydration is generally difficult, conditions can be provided to favor the production of an isomer. For example, dehydration of isobutanol at 280 °C over a γ-alumina catalyst can be provided to produce up to 97% isobutylene despite an expected equilibrium concentration of ˜57% at that temperature. However, there is currently no known method for cleanly dehydrating isobutanol to 99+% isobutylene (Saad L and Riad M, J Serbian Chem Soc 2008 (73) 997). Thus, dehydration of isobutanol typically yields a mixture of butenes, primarily isobutylene. However, in certain cases, larger amounts of linear butenes may be desired, and process conditions may be adjusted accordingly. The product butenes are then separated from the bulk of the water by, e.g., distillation, etc. Butene Feeds [0044] Butene feeds (also referred to herein as butene streams) of the present disclosure can be used in processes such as feeds for butyl ether processes (butyl ether unit 120 via line 118) and/or acid extraction processes (such as acid extraction unit 110 via line 126 or via line 140 or via line 134) described in more detail below. Butene feeds can be obtained from one or more sources such as a butene feeds produced by cracking, e.g., hydrocracking and/or fluidized catalytic cracking of isobutanol (in cracking unit 138), and/or by isobutanol pyrolysis. In some embodiments, catalytic cracking of isobutanol is performed by recovering a catalytic primary fractionator overheads (C5 minus) fraction by deethanizing, debutanizing, and depropanizing in a light ends fractionation train. [0045] In some embodiments, catalytic cracking of isobutanol can be performed at a temperature of about 450 ^oC to about 650 ^oC at pressures of about 250 kPa to about 400 kPa. Catalyst used for catalytic cracking can be amorphous silica-alumina and/or crystalline aluminosilicates known as molecular sieves or zeolites to provide strong carbonium ion activity (and/or proton transfer). In such processes, isobutanol is introduced with moving catalyst stream for a short period of time. Spent catalyst can be moved continuously into a regenerator where deposits on the catalyst can be burned off. The freshly regenerated catalyst moves back to the reactor to continue reacting with fresh isobutanol. [0046] In some embodiments, the butene feed (butene stream) comprises ≧0.1 wt% of C4 olefins based on the weight of the butene feed. For example, the butene feed can comprise ≧50.0 wt% of C4 mono olefins based on the weight of the first olefin mixture, such as ≧90.0 wt% of C4 mono olefins. The C4 mono olefins of the butene feed are generally a mixture of 1-butene, 2-butenes, and isobutylene which can vary in composition. For example, the C4 mono olefins in the butene feed can comprise ≧1.0 wt% of 1-butene, such as in the range of from 1.0 wt% to 40.0 wt%; ≧2.0 wt% of 2- butenes, such as in the range of from 2.0 wt% to 45.0 wt%; and ≧1.0 wt% of isobutylene, such as in the range of 1.0 wt% to 30.0 wt%, the weight percent of each species is based on the weight of the first olefin mixture's C4 mono olefins. Besides C4 mono olefins, the butene feed can contain other hydrocarbon species such as propane, n-butane, isobutane, pentane or hexane. Light oxygenate species such as methanol or dimethylether (“DME”) may also be present in amounts ≦1.0 wt%. In at least one embodiment, the butene feed comprises ≧20.0 wt% normal butenes, and ≧20.0 wt% isobutylene, and optionally further comprises ≦5.0 wt% propane, ≦15.0 wt% n-butane, ≦25.0 wt% isobutane, ≦1.0 wt% pentane. Butyl Ether Synthesis [0047] A method for preparing butyl ethers (such as methyl tert-butyl ether (MTBE) or ethyl tert- butyl ether) in butyl ether unit 120 in high purity from a butene stream includes feeding the butene stream and methanol (or ethanol) to a reactor, which is packed with a properly supported catalyst, contacting the butene feed and methanol with the catalyst to react methanol and isobutylene, and then fractionating the ether from the normal butene. [0048] Methyl tert-butyl ether is formed by the exothermic reaction of isobutylene and methanol, such as in the liquid phase, catalyzed by an acidic resin catalyst. High temperature favors the kinetic rate of reaction, whereas low temperature favors the equilibrium conversion to MTBE. Increasing methanol, decreasing temperature, and increasing feed isobutylene concentration all favor equilibrium conversion. In a typical adiabatic reactor, the reaction becomes self-quenching because heat released by the reaction continues to increase reactor temperature until equilibrium composition is reached. If the inlet temperature is too high, equilibrium temperature is reached quickly and only part of the catalyst bed is used. If inlet temperature is too low, the reaction rate is slow and conversion is low. At a sufficient inlet temperature, equilibrium is achieved and full catalyst bed can be utilized. [0049] In some embodiments, a process for forming MTBE is performed using an acidic sulfonated macroporous polystyrene-divinyl benzene ion exchange resin, such as those commercially available from LANXESS®/LENNTECH® under the tradename LEWATIT® or AMBERLYST® 15 or 15C available from DUPONT®. [0050] In some embodiments, a mixture of butene feed and methanol is preheated (e.g., to about 140 ^oF to about 160 ^oF, such as about 150 ^oF) and introduced to a guard bed (of the butyl ether formation unit 120). The mixture is provided to the guard bed reactor at an inlet temperature of about 130 ^oF to about 160 ^oF. The guard bed can be a boiling point reactor, providing substantial conversion to butyl ether. Heat released by the exothermic heat of reaction can be used to vaporize reactants/products, resulting in only a small temperature rise across the reactor. Reactor outlet temperature (e.g., about 170 ^oF to about 175 ^oF) can be controlled by a back pressure control valve on the reactor outlet. Outlet pressure can be about 105 psig to about 115 psig. An online analyzer can be utilized to measure isobutylene concentration in the butene feed so an operator can adjust any rapid feed composition swings. One or more pumps upstream of the guard bed can be utilized to maintain reactor pressure drop to any suitable level, such as 15 psi to 50 psi, e.g., at an outlet pressure of 110 psig. Catalyst volume can be set to provide a space velocity of about 5 V/H/V to about 10 V/H/V, such as about 7 V/H/V based on catalyst in the mixture of butene feed/methanol. A molar ratio of methanol/butenes at the guard bed inlet can be about 1:1 to about 2:1, such as about 1:3. To compensate for any catalyst deactivation over time, the guard bed temperature can be increased, e.g., to an inlet temperature of about 150 ^oF to about 170 ^oF, such as about 160 ^oF. As the reaction in the guard bed is self-quenching, temperature runaway in the guard bed is not of concern. [0051] The effluent from the guard bed is a two phase effluent (MTBE and C₄ raffinate) that passes to a synthesis tower where additional isobutylene conversion occurs and the MTBE product is separated from the C₄ raffinate. The synthesis tower can have a catalyst zone at about a half tower height (midway in the tower) with rectification trays above and stripping trays below the catalyst zone. The feed to the reactor can be positioned such that MTBE present in the feed can be fractionated away from the feed before the vapor enters the catalyst zone. The catalyst zone can be formed by packing the catalyst (e.g., Amberlyst 15) into a fiberglass belt which is rolled with open stainless steel wire mesh to form a bale. The tower can operate at an overhead pressure of about 80 psig to about 120 psig, such as about 100 psig. The reflux rate in the tower can be about 0.5 L/D to about 1 L/D, such as about 0.75 L/D. Increasing reflux rate increases conversion by recycling unconverted butene feed and methanol back to the catalyst zone. The temperature of the catalyst zone can be about 140 ^oF to about 160 ^oF, such as about 150 ^oF to about 155 ^oF. Temperatures higher than 160 ^oF tend to decrease conversion to MTBE. [0052] C4 raffinate containing methanol taken from the overhead in the synthesis tower (of the butyl ether formation unit 120) can be cooled to about 90 ^oF to about 110 ^oF, such as about 100 ^oF, and sent to a raffinate methanol extractor for water wash extracting methanol from the C4 raffinate with demineralized water. A weight ratio of water to methanol is about 2:1 to about 6:1, such as about 4:1. Raffinate from the methanol extractor can be sent to a raffinate DME tower. DME levels can overhydrate the catalyst, resulting in reduced catalyst life. The methanol containing water wash stream(s) from the methanol extractor is sent to a methanol recovery tower to distill methanol overhead from the water and recycle the methanol back to the synthesis reactor. The water taken as bottoms from the recovery tower is sent back to the methanol extractor. [0053] Crude MTBE from the synthesis tower (of the butyl ether formation unit 120) flows to an MTBE topping tower where the C5s introduced with the catalyst cracked C4s are separated from the MTBE. MTBE bottoms stream from the MTBE topping tower is sent to an MTBE tailing tower where heavy reaction byproducts are separated from the MTBE. For example, MSBE byproduct is separated from the MTBE. MSBE may be passed through the decomposition reactor(s) (described below) and recycled to the synthesis section. Overhead MTBE recovery can be 99% or greater, such as 99.7% or greater. [0054] On a stoichiometric equivalencies basis, equimolar quantities of methanol and isoolefins are advantageous but an excess between 2 and 250% of either component can be passed to the etherification reaction unit. In some embodiments, the molar ratio of alkanol to iso-olefin, such as methanol to iso-butylene, can be between about 0.7 and 2, such as the molar ratio is 1 for methanol to isobutylene. [0055] In the presence of acidic catalysts, such as zeolite catalyst, some olefin dimerization can occur during etherification. This side reaction lowers the selectivity of the process for the production of tertiary alkyl ether. If ether of high purity is desired, dimer formation in any significant quantity also involves a distillation to separate the dimer, or higher oligomers, from tertiary alkyl ether product. If a large excess of alkanol is used to retard the formation of dimer, recovery of the unreacted alkanol also involves a distillation and/or extraction. [0056] In alternative embodiments, in addition to or instead of methanol, other alkanols are utilized, such as ethanol, 1-propanol, isopropanol, 1-butanol, 2-butanol and isobutanol. Alkyl tert- alkyl ethers produced can include MTBE, TAME, ethyl tertiary butyl ether, ethyl tertiary amyl ether, n-propyl tertiary butyl ether, n-propyl tertiary amyl ether, isopropyl tertiary butyl ether, isopropyl tertiary amyl ether, n-butyl tertiary butyl ether, n-butyl tertiary amyl ether, sec-butyl tertiary butyl ether, sec-butyl tertiary amyl ether, and the like. [0057] The zeolite etherification catalysts for use herein can include the crystalline aluminosilicate zeolites having a silica to alumina ratio of at least 12, a constraint index of about 1 to 12 and acid cracking activity greater than about 20, such as about 30 to about 300, such as about 50 to about 250. Representative of the ZSM-5 type zeolites are ZSM-5, ZSM-11, ZSM-23, ZSM-35, and ZSM-48. ZSM-5 is disclosed and claimed in U.S. Pat. No.3,702,886 and U.S. Pat. No. Re.29,948; ZSM-11 is disclosed and claimed in U.S. Pat. No.3,709,979. Also, see U.S. Pat. No.4,076,842 for ZSM-23; U.S. Pat. No. 4,016,245 for ZSM-35. The disclosures of these patents are incorporated herein by reference. [0058] In general, the useful catalysts embrace two categories of zeolite, namely, the intermediate pore size variety as represented, for example, by ZSM-5, which possess a Constraint Index of greater than about 2 and the large pore variety as represented, for example, by zeolites Y and Beta, which possess a Constraint index no greater than about 2. Both varieties of zeolites will possess a framework silicato-alumina ratio of greater than about 7. [0059] A convenient measure of the extent to which a zeolite provides controlled access to molecules of varying sizes to its internal structure is the aforementioned Constraint Index of the zeolite. A zeolite which provides relatively restricted access to, and egress from, its internal structure is characterized by a relatively high value for the Constraint Index, e.g., about or greater than 2. On the other hand, zeolites which provide relatively free access to the internal zeolitic structure have a relatively low value for the Constraint Index, e.g., about 2 or less. The method by which Constraint Index is determined is described fully in U.S. Pat. No. 4,016,218, to which reference is made for details of the method. [0060] Constraint Index (CI) values for some zeolites which can be used in the process of this invention are: _Table 1______________________________________________________________ Zeolite Constraint Index At Test Temperature, °C. _____________________________________________________________________ ZSM-4 0.5 316 ZSM-5 6-8.3 371-316 ZSM-11 5-8.7 371-316 ZSM-20 0.5 371 ZSM-35 4.5 454 ZSM-38 2 510 ZSM-48 3.5 538 ZSM-50 2.1 427 TMA Offretite 3.7 316 TEA Mordenite 0.4 316 Clinoptilolite 3.4 510 Mordenite 0.5 316 REY 0.4 316 Amorphous Silica-Alumina 0.6 538 Dealuminized Y 0.5 510 Zeolite Beta 0.6-2.0 316-399 _____________________________________________________________________ [0061] The large pore zeolites which are useful as catalysts in the process, e.g., those zeolites having a Constraint Index of no greater than about 2, are well known to the art. Representative of these zeolites are zeolite Beta, zeolite X, zeolite L, zeolite Y, ultrastable zeolite Y (USY), dealuminized Y (Deal Y), rare earth-exchanged zeolite Y (REY), rare earth-exchanged dealuminized Y (RE Deal Y), mordenite, ZSM-3, ZSM-4, ZSM-20, and ZSM-50 and mixtures of any of the foregoing. Although zeolite Beta has a Constraint Index of about 2 or less, it should be noted that this zeolite does not behave exactly like other large pore zeolites. However, zeolite Beta does satisfy the requirements for a catalyst of the present invention. [0062] Zeolite Beta is described in U.S. Re. Pat. No.28,341 (of original U.S. Pat. No.3,308,069), to which reference is made for details of this catalyst. [0063] In practicing the etherification process, it can be advantageous to incorporate the zeolite(s) into some other material, e.g., a matrix or binder, which is resistant to the temperature and other conditions employed in the process. Useful matrix materials include both synthetic and naturally- occurring substances, e.g., inorganic materials such as clay, silica and/or metal oxides. Such materials can be either naturally-occurring or can be obtained as gelatinous precipitates or gels including mixtures of silica and metal oxides. The zeolite(s) employed herein can be composited with a porous matrix material such as carbon alumina, titania, zirconia, silica, silica-alumina, silica-magnesia, silica-zirconia, silica-thoria, silica-beryllia, silica-titania, etc., as well as ternary oxide composition, such as silica-alumina-thoria, silica-aluminazirconia, silica-alumina-magnesia, silica-magnesia- zirconia, etc. The matrix can be in the form of a cogel. The relative proportions of zeolite component(s) and matrix material, on an anhydrous basis, can vary widely with the zeolite content ranging from between 1 to about 99 wt %, and more usually in the range of about 5 to about 90 wt % of the dry composite. In some cases, it may be advantageous to provide the zeolite etherification catalyst(s) in the form of an extrudate bound with a low acidity refractory oxide binder. The minimum dimension of the catalyst particle may be 1/32 to 1/4 inch. [0064] The zeolite(s) selected for use herein will generally possess an alpha value after steaming or hydrothermal treatment of at least about 10, such as at least 30, such as at least about 50. "Alpha value", or "alpha number", is a measure of zeolite acidic functionality and is more fully described together with details of its measurement in U.S. Pat. No.4,016,218, J. Catalysis, 6, pp.278-287 (1966) and J. Catalysis, 61, pp. 390-396 (1980). The procedure outlined in the latter reference (1980) has been used to determine the alpha values cited in this invention. Zeolites of low acidity (alpha values of less than about 300) can be achieved by steaming or hydrothermal treatment. In the case of steaming, the zeolite(s) can be exposed to steam at elevated temperatures ranging from about 500 °F to about 1200 °F, such as about 750 °F (260 °C) to about 1000 °F (538 °C). This treatment can be accomplished in an atmosphere of 100% steam or an atmosphere consisting of steam and a gas which is substantially inert to the zeolite. A similar treatment can be accomplished at lower temperatures employing elevated pressure, e.g., at from about 350 °F (177 °C) to about 700 °F (371 °C) with from about 10 to about 200 atmospheres. Specific details of several steaming procedures may be gained from the disclosures of U.S. Pat. Nos.4,325,994; 4,374,296; and 4,418,235. [0065] Pretreatment by steaming or hydrothermal treatment of the zeolite catalyst, particularly zeolite beta catalyst, selectively reduces the rate of oligomerization compared to that of etherification in the process for the production of alkyl tert-alkyl ethers. Thus, the yield of oligomer is considerably reduced with only a smaller effect on the yield of ether. Further, it is believed that aging will also be improved by a pretreatment comprising steaming or hydrothermally treating zeolite beta catalyst in the etherification process. Selectivity to ether products compared to olefin oligomerization products is improved. Catalyst aging is projected to improve as well. The improvements can be accomplished by pretreating the catalyst by steaming, e.g., gaseous water at elevated temperatures, or by hydrothermal treatment employing liquid water at elevated temperature. The improvement particularly applies to catalytic particles comprising beta zeolite crystals, which may include binder material such as alumina, silica, zirconia, titania, carbon, etc. The improvement most particularly applies to extruded zeolite beta containing catalyst bound with alumina or zirconia. The improvement is effective when olefins (e.g., C₄ olefin mixtures, C₅ olefin mixtures, C₄-C₅ olefin mixtures, or C₄- C₈ olefin mixtures) are etherified with a monohydric C₁ to C₅ alcohol, or mixtures, as described above. [0066] Improvement of the catalyst by steam treatment can be accomplished by contacting the zeolite beta catalyst particles with steam at elevated temperature. Temperatures above 300 °C can be used, such as above 400 °C, such as above 450 °C. Steam pressures of above about 0.1 atmosphere are utilized, such as about 0.5 to about 5 atm, such as about 0.8 to about 2 atm. Contacting times of from several minutes to days are used, such as about 1 to about 50 hrs, such as about 2 to about 24 hrs. Higher steam pressures and temperatures are associated with shorter treatment times. Successful steaming results in a zeolite alpha value that is about 80% of the untreated zeolite, or lower. Steaming to give an alpha value of 10% to 75% of the untreated zeolite can be performed, or alpha values as indicated above. [0067] Improvement of the catalyst by hydrothermal treatment can be accomplished by contacting zeolite beta catalyst particles with liquid water at elevated temperatures. Temperatures above 100 °C can be used, such as above 125 °C, such as above 150 °C. Treatment pressure should be high enough to maintain liquid water. Contact times of from several hours to several days are used. Higher temperatures are associated with shorter treatment times. Successful hydrothermal treatment results in a zeolite alpha value that is about 80% of the untreated zeolite, or lower. Hydrothermal treatment to give an alpha value of 10% to 75% of the untreated zeolite can be performed, or alpha values as indicated above. [0068] In some embodiments, a process includes producing butyl ether from alkanol and butene feed utilizes zeolite catalyst, particularly zeolite beta, that results in a high ether selectivity and a significant reduction in the formation of olefin oligomer by-product. In such embodiments, a catalyst pretreatment step can be utilized. The zeolite catalyst pretreatment includes either steaming or a hydrothermal treatment using liquid water at elevated temperature. The process is particularly effective in reducing the formation of dimer by-product in the zeolite beta catalyzed process for the formation of MTBE with high selectivity. Other catalysts suitable for MTBE formation can include ZSM-5. Methyl Tert-Butyl Ether Decomposition [0069] The MTBE recovered from the MTBE tailing tower described above (of butyl ether formation unit 122) is provided to an MTBE decomposition reactor(s) (of butyl ether decomposition unit 124), which may be two decomposition reactors in parallel or in series. The reactors can be in parallel, for example, to allow either reactor to be taken out of service for catalyst changeout while the other reactor remains on stream. Nitrogen can be used to purge a reactor after catalyst changeout. The decomposition reactor(s) can be isothermal reactors (heat exchanger reactors) with a catalyst (e.g., HF acid treated attapulgite clay having a bulk density of about 38.7 lb/ft³, a surface area of 135 m²/g, and a pore volume of about 0.55 cc/g) packed in tubes. Attapulgate clay is non-corrosive, allowing use of carbon steel tubes in the reactor(s). A reactor pressure can be about 50 psig to about 150 psig, such as about 50 psig to about 125 psig, such as about 70 psig to about 80 psig, such as about 75 psig. Low reactor pressure favors the conversion of MTBE to isobutylene and methanol. The conversion of decomposition can be controlled by steam pressure and flow rate to the reactor(s). As the catalyst deactivates, steam pressure can be increased to compensate for loss of catalyst activity. Flow of MTBE to the reactor is increased at higher conversion catalyst conditions to provide excellent conversion of MTBE to isobutylene. The endothermic heat of reaction can be supplied by steam (e.g., about 150 psig to about 450 psig, such as about 300 psig) on the shell side of the reactors. A second steam supply (e.g., about 100 psig to about 150 psig, such as about 125 psig) can be provided as a backup for the first steam supply. [0070] An effluent from the decomposition reactor effluent, after heat removal, flows to a crude tower (of butyl ether decomposition unit 124) where isobutylene and azeotropic amount of methanol are separated from overhead from the unreacted MTBE and the bulk of the methanol. A tower bottoms stream containing methanol, MTBE, and MSBE is recycled to the guard bed described above as methanol feed. [0071] The isobutylene/methanol azeotrope from the crude tower (of butyl ether decomposition unit 124) is provided to an extractor where the azeotrope is water washed for methanol removal. A weight ratio of water to methanol can be about 2:1 to about 6:1, such as about 4:1. [0072] The isobutylene obtained from the extractor (of butyl ether decomposition unit 124) is provided to a product DME tower for further product purification to remove DME as well as drying the product isobutylene. [0073] In some embodiments, conditions used to decompose the butyl ether in a decomposition reactor include a temperature of about 50 °C to about 320 °C, a pressure of about 0 kPa to about 3500 kPa, and a weight hourly space velocity (WHSV) of about 0.1 hr⁻¹ to about 25 hr⁻¹; such as a temperature of about 100 °C to about 275 °C, a pressure of about 0 kPa to about 2400 kPa, and a weight hourly space velocity (WHSV) of about 0.5 hr⁻¹ to about 10 hr⁻¹. [0074] In some embodiments, suitable ether decomposition conditions include a temperature of about 100 °C to about 200 °C and a pressure of about 0 kPa to about 1000 kPa and a weight hourly space velocity (WHSV) of about 1 hr⁻¹ to about 10 hr⁻¹. [0075] In some embodiments, a catalyst used for butyl ether decomposition is a mixed metal oxide comprising at least one first metal selected from Group 4 of the Periodic Table of Elements and at least one second metal selected from Group 3 (including the Lanthanides and Actinides) and Group 6 of the Periodic Table of Elements (International Union of Pure and Applied Chemistry, 2023). [0076] Suitable Group 4 metals include titanium, zirconium and hafnium, such as zirconium. Suitable Group 3 metals include scandium, yttrium and lanthanum, and metals from the Lanthanide or Actinide series, such as cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium and thorium. In some embodiments, a Group 3 metal is cerium. Suitable Group 6 metals include chromium, molybdenum, and tungsten, such as tungsten. The first and second metal species present in the final catalyst are not limited to any particular valence state and may be present in any positive oxidation value possible for the respective species. [0077] Other metals, such as metals of Groups 7, 8, and 11 of the Periodic Table of Elements, for example iron, manganese, and/or copper, may optionally be added to the present catalyst to alter its catalytic properties. [0078] In one embodiment, the mixed metal oxide catalyst composition of the invention has the following empirical formula: ^X _m ^Y _n ^Z _p ^O _q where X is at least one metal selected from Group 4 of the Periodic Table of Elements, Y is at least one metal selected from Group 3 (including the Lanthanides and Actinides) and Group 6 of the Periodic Table of Elements, and Z is at least one metal selected from Groups 7, 8, and 11 of the Periodic Table of Elements; m, n, p and q are the atomic ratios of their respective components and, when m is 1, n is from about 0.01 to about 0.75, such as from about 0.02 to about 0.6; p is 0 to about 0.1, such as from about 0 to about 0.05; and q is the number of oxygen atoms necessary to satisfy the valence of the other components. [0079] The mixed metal oxide composition employed in the process of the invention is produced by chemical interaction of a Group 4 metal oxide with an oxide or oxyanion of a Group 3 and/or 6 metal. The catalysts selected for the purposes of the present invention exhibit very selectivity for ether decomposition, while minimizing side-reactions. While the authors do not wish to be bound by any theory, it seems that the selection of the particular metal elements and/or their relative ratios and/or the presence of sulfur, such as in specific amounts, provide acidic properties particularly well suited for ether decomposition. [0080] The mixed oxides can contain sulfur, conveniently provided by the presence of sulfate ions in the precursor mixture. Sulfur is typically present in an amount of up to 5 wt %, such as up to 1 wt %, of the final mixed oxide composition. [0081] The present mixed metal oxides may be composited with an inactive matrix material to form the finished form of the catalysts and for this purpose conventional matrix materials such as alumina and silica are suitable, such as silica as a non-acidic binder. Other binder materials may be used, for example, titania, zirconia and other metal oxides or clays. If a matrix is used, the active catalyst may be composited with the matrix in amounts from 90:10 to 10:90 by weight, e.g., from 80:20 to 20:80, or from 70:30 to 30:70 active catalyst:matrix. Compositing may be done by conventional means including mulling the materials together followed by extrusion or pelletizing into the desired finished catalyst particles. [0082] In alternative embodiments, butyl ether can be decomposed using a catalyst prepared by reacting a naturally occurring or synthetic clay with HF or HCl followed by calcining. The reacting or incorporation of the HF of HCl with the clay can be accomplished by contacting the clay with anhydrous HF or HCl gas or by impregnation of the clay with the aqueous acid (e.g., mixing method equilibrium adsorption method, evaporation-to-dryness method, spraying method). [0083] In some embodiments, the clay is reacted with about 1 to about 70 wt%, such as about 20 to about 50 wt% hydrofluoric acid or 1.0 to 37%, such as about 20 to about 30 wt% hydrochloric acid at temperatures of about 0 °C to about 50 °C, such as about 10 °C to about 30 °C for about 30 to about 120 minutes. The amount of the acid is about 0.001 to about 1.0, such as about 0.01 to about 0.10 grams anhydrous acid/gram clay. Following reaction, the fluid is decanted and the clay is then washed first with water and then with alcohol before calcining. [0084] The calcining temperature is selected so as to achieve a highly active high surface area catalyst of a moisture content of less than 5% by wt. For example, temperatures are about 250 °C to about 1000 °C, such as about 400° to about 700° C. [0085] The calcination is generally carried out in air, but an atmosphere of an inert gas (e.g., nitrogen, carbon dioxide, argon), steam or mixtures thereof may also be used. [0086] The time for calcination is generally about 0.1 to about 24 hours, such as about 0.5 to about 10 hours, although it depends upon the calcination temperature. The amount of the fluorine or chlorine compound supported on the carrier is about 0.1 to about 100 parts by weight of the carrier, such as about 1.5% to about 6.0%. [0087] As examples of the carrier containing silicon oxides, there may be silica, montmorillonite, kaolinite, attapulgite, bentoninte, acid clay, or combinations thereof. Besides these, silica-alumina, silica-zirconia, silica-magnesia, and their mixtures may also be used. Silica may be used in either the form of gel or sol. An example carrier is one prepared from attapulgite or montmorillonite type minerals. The surface area of the carrier is not particularly limiting, such as it is more than 1 m²/g, such as above 40 m²/gm. Example surface areas after calcination are in the range of 100 m²/gm to 400 m²/gm. [0088] HF or HCl treated catalysts of the present disclosure can provide extended catalytic life which is important for industrial use. The extended catalyst life is due at least in part to the high stability of HF or HCl treated clay as opposed to other acid treated clays. Thus, it is known that acids such as H₂SO₄ and H₃PO₄ in the presence of components such as alcohols form esters which under the reaction conditions are volatile thereby changing the acidity of the catalyst as it ages. The HF and HCl treated clays have essentially the same halide level before and after use. [0089] The reaction of decompositon of the butyl ethers takes place with good yields under atmospheric pressures, but can be operated under slightly superatmospheric pressures so as to permit the use of cooling water without any other expedient to carry out the condensation of the products which are obtained. The working pressures can range from about 1 to about 20 kilograms/cm² absolute; such as under a pressure which is at least equal to the vapor pressure of the described olefin at the condensation temperature. [0090] In some embodiments, the reaction is carried out at a temperature below 250 °C, such as about 100 °C to about 250 °C, such as about 110 °C to about 230 °C. The reaction is carried out at a spatial velocity, as expressed in terms of volume of liquid per volume of catalyst per hour (LHSV) such as about 0.5 to about 30, such as about 1 to about 5. [0091] As an example, conditions are selected to obtain conversions of the butyl ethers above 80%, such as above 90%. Acid Extraction of Isobutylene [0092] In some embodiments, acid extraction of a butene feed (such as of line 126, line 140, or line 134 of system 100) can be performed forming tert-butanol. The tert-butanol formed can then undergo dehydration (in tert-butanol dehydration unit 130), as described above. [0093] In some embodiments, the acid extraction unit 110 and tert-butanol dehydration unit 130 can together include a regenerator reboiler, tert-butanol waste water tower, a vent tower, a pressurized isobutylene product wash tower, and an extraction section. For the regenerator reboiler, a steam injected into the regenerator is condensed which lowers the regenerator bottoms acid concentration. Incorporating a reboiler reduces the amount of acid dilution due to steam injection and thus redcues the size and heat duty of the acid concentrator, reducing plant investment, steam consumption, cooling water consumption and waste water rate. Also, since less water is vaporized in the acid concentrator, acid losses are lower, which reduces caustic consumption for neutralization. For the tert-butanol waste water tower, tert-butanol will be reduced in the waste water, such as to less than 50 ppm, by stripping process waste water. Also, recovery of isobutylene is improved by concentrating the tert- butanol in the overhead and recycling tert-butanol back to the acid extraction section. For the vent tower, isobutylene regeneration is shown where n-butenes can be stripped in the vent tower. For the isobutylene product wash tower, water washing at high pressure is performed to reduce oxygenated compounds in the isobutylene product, providing use of a smaller and more efficient absorption tower. Lastly, the static mixers of the extraction section can increase the capacity of ther extraction section by increasing the interfacial area for mass transfer. The extraction rate in the extraction section is mass transfer limited rather than reaction rate limited. By placing the static mixer(s) at this location, where the driving force for the hydration reaction is greatest, the largest extraction rate increase is achieved. The static mixers also decrease isobutylene losses in the spent C4 stream which improves isobutylene recovery. [0094] Acid extraction can be performed by a two-stage countercurrent extraction process. The first stage can be a “rich stage” and can be performed at a temperature of about 90 ^oF to about 110 ^oF, such as about 100 ^oF, and/or at a molar ratio of tert-butanol to H₂SO₄ of about 1:1 to about 2:1, such as about 1.5:1. The second stage can be a “lean stage” and can be performed at a temperature of about 60 ^oF to about 80 ^oF, such as about 70 ^oF, and/or at a molar ratio of tert-butanol to H₂SO₄ of about 0.15:1 to about 0.2:1. The rich and lean stages are operated at pressures independently of about 90 psig to about 110 psig, such as about 100 psig to about 105 psig. Fresh butene feed to the extraction first goes to a feed surge drum. Vent gas, containing mostly isobutylene and normal butenes, is compressed and condensed and recycled to the feed surge drum and combined with the butene feed. [0095] From the surge drum, the butene feed is pumped into the emulsion circulation of the reactor. From the lean stage settler, the lean extract, which contains sulfuric acid and tert-butanol, is also pumped into the rich stage emulsion circulation. Tert-butanol from the alcohol accumulator and from the overhead of the tert-butanol recovery tower is recycled to the emulsion circulation. The purpose of the emulsion circulation is to increase the mixing of the hydrocarbon with the acid and water and to remove the heat of hydration os isobutylene to tert-butanol. The emulsion circulation passes through a static mixer to increase the mixing action. The emulsion then goes through a rich stage cooler to remove the heat of hydration. The emulsion circulation enters the reactor through spargers, which provide additional mixing. [0096] The emulsion of hydrocarbon, tert-butanol, H₂SO₄, and water overflows the rich stage reactor and flow to the rich stage settler. The emulsion separates into two phases. The acid phase which contains tert-butanol, H₂SO₄, and water settles as a bottoms phase and comprises the rich extract which leaves the extraction section and flows to the vent tower. The hydrocarbon, which is a rich raffinate, is drawn off the top. [0097] The rich raffinate flows from the rich stage settler to the emulsion circulation of the lean stage reactor. Concentrated acid from the acid storage tank mixes with the rich raffinate in the emulsion circulation. The emulsion passes through the lean stage cooler and returns to the lean stage reactor through spargers. The emulsion overflows the lean stage reactor and flows to the lean stage settler. As in the rich stage settler, the emulsion separates into two phases. The acid phase, containing the acid, water, and tert-butanol, is the lean extract which is pumped back to the rich stage reactor emulsion circulation circuit. The hydrocarbon phase, containing the unextracted normal butenes and butanes, makes up the lean raffinate stream which goes on to the spent butene purification section. [0098] The lean raffinate, containing the unextracted butenes or “spent butenes”, enters a spent butene caustic scrubber and flows into a reservoir filled with caustic where butenes are heated to their bubble point using open steam. Butenes which overflow the reservoir are vaporized on stripping trays using steam injection. As butene travels up the tower, it is neutralized with caustic on the top trays. The overhead vapor from the caustic scrubber goes to the water wash tower to reduce the content of tert-butanol and other oxygenated compounds to, for example, 10 ppm or less. To prevent hydrocarbon condensation in the water wash tower, the spent butenes are let down in pressure in going from the caustic scrubber to the water wash tower so that the spent butenes are 15-20 ^oF above their dew point. Wash water is at the same temperature as the butene vapor. The liquid to vapor mole ratio in the tower can be set to about 1:1 to about 2:1, such as about 1.6:1, to achieve the cleanup. [0099] The rich extract from the rich stage settler is sent to the vent tower. In the vent tower, dissolved n-butenes in the extract are removed and thus lower the n-butenes content in the isobutylene product. Steam is injected into the feed at the bottom of the vent tower. The steam injected in the feed heats the feed and improves the initial flashing of n-butenes into the tower. Also, the vent tower has trays to provide sufficient contacting so that n-butenes can be stripped by isobutylene vapor, which is regenerated in the bottom of the tower by the injected steam. The normal butenes which are flashed and stripped and the iso-butylene which is regenerated in the vent tower go overhead. The isobutylene concentration in the vent gas is between 40-50 wt%. The vent gas also contains tert- butanol and any other hydrocarbons which were in the vent tower feed. The vent tower overhead pressure can be about 1 psig to about 5 psig, such as about 2 psig to about 3 psig and temperature can be about 140 ^oF to about 160 ^oF, such as about 50 ^oF. From the vent tower, gas goes to the vent gas scrubber where it is neutralized with NaOH and washed, to prevent caustic carryover, using 98 ^oF plant wastewater from the bottom of the tert-butanol tower. Most of the tert-butanol is washed out of the vent gas and ends up in the bottoms which after combining with the isobutylene wash tower bottoms is sent to the isobutylene caustic scrubber. The vent gas scrubber overhead is provided to a knockout drum to knock out any entrained liquid and is then compressed (e.g., up to about 60 psig) by the vent gas compressor. The compressed vent gas is condensed and recycled to the butene feed surge drum. [0100] From the bottom of the vent tower, the rich extract is provided to the regenerator (of tert- butanol dehydration unit 130). In some embodiments, in the regenerator, heat is supplied by live steam and by the reboiler to dehydrate tert-butanol to isobutylene and water. 50% of the heat is supplied by steam with the remainder supplied by the reboiler. The conversion to isobutylene can be about 80% or greater, such as about 85% or greater. The isobutylene and unconverted tert-butanol go overhead to an isobutylene purification section. The acid plus water, which includes condensed steam, are provided out of the regenerator bottoms to the acid concentrator. The regenerator overhead pressure can be about 1 psig to about 10 psig, such as about 5 psig, and temperature can be about 140 ^oF to about 160 ^oF, such as about 150 ^oF. The regenerator bottoms temperature can be about 260 ^oF to about 280 ^oF, such as about 270 ^oF, and the pressure can be about 5 psig to about 10 psig, such as about 7 psig. In alternative embodiments, in the regenerator, all of the heat used to dehydrate the tert- butanol to isobutylene is supplied by the reboiler with no live steam injection. The reboiler also serves as an acid concentrator and maintains the bottoms acid concetration in a range of about 50 wt% to about 65 wt%, such as about 58 wt%, by vaporizing the water contained in the alcohol recycle streams and the condensed vent tower steam which diluted the acid. At least a portion of the vaporized water is recycled to the vent tower from the bottom of the regenerator with the remainder exiting in the regenerator overhead. Routing the vaporized water to the vent tower is optional. Part of this steam can be used in the isobutylene caustic scrubber or a larger portion can exit in the regenerator overhead. The bottoms acid is sent to the acid tank after being cooled from a high of about 290 ^oF to about 310 ^oF, such as about 305 ^oF, to a low of about 90 ^oF to about 110 ^oF, such as about 100 ^oF. From the acid tank, it is recycled to the lean stage reactor. [0101] For isobutylene purification, the overhead of the regenerator can be provided to the caustic scrubber. The caustic scrubber has trays and between two trays there is a caustic reservoir to neutralize unusual acid carryover due to foaming in the regenerator. The bottoms water from the vent gas scrubber and the isobutylene wash tower are combined and routed to the top of the caustic scrubber to wash the rising vapor to prevent caustic carryonver. Steam at about 10 psig to about 30 psig, such as about 20 psig, can be introduced below the first tray. The steam strips tert-butanol which might have condensded. The steam also strips the tert-butanol contained in the wash water from the vent gas scrubber and isobutylene wash tower. The caustic scrubber bottoms, at a temperature of about 210 ^oF to about 230 ^oF, such as about 220 ^oF, is pumped to the tert-butanol recovery section. The caustic scrubber overhead, containing the isobutylene/tert-butanol vapor at a pressure of about 2 psig to about 6 psig, such as about 4 psig, and a temperature of about 130 ^oF to about 150 ^oF, such as about 140 ^oF, is provided to a partial condenser where most of the tert-butanol is condensed. The tert- butanol is collected in an alcohol accumulator and is pumped back to the rich stage emulsion circulation circuit. The vapor from the alcohol accumulator goes to the isobutylene compressor and is compressed to about 50 psig to about 70 psig, such as about 60 psig. The vapor is cooled from the compressor discharge temperature of about 200 ^oF to about 220 ^oF, such as about 210 ^oF, to a lower temperature of about 120 ^oF to about 130 ^oF, such as about 125 ^oF (e.g., about 15-20 ^oF above the dew point of the isobutylene vapor) before going to the water wash tower. Tert-butanol and other oxygenated compounds which are contained in the isobutylene vapor are removed in the water wash tower. To prevent hydrocarbon condensation the wash water temperature can be about 120 ^oF to about 130 ^oF, such as about 125 ^oF. The wash water tower overhead is condensed and pumped to storage or directly to a butyl rubber reactor. [0102] Waste water from the spent butene caustic scrubber, spent butene wash tower, isobutylene caustic scrubber and condensate from the acid concentrator are collected in the tert-butanol tower feed surge drum. Polymer contained in the waste water is drawn off the top of the surge drum and is pumped elsewhere. The water and alcohol phase is pumped to the tert-butanol tower. The water and alcohol mixture enters the tert-butanol tower at an upper tray location. The tower operates at an overhead pressure of about 10 psig to about 18 psig, such as about 14 psig, and a temperature of about 200 ^oF to about 220 ^oF, such as about 210 ^oF. The tower operates at a bottoms temperature of about 250 ^oF to about 270 ^oF, such as about 260 ^oF. Steam (about 140 psig to about 160 psig, such as about 150 psig) is injected at a bottom tray location. The tower bottoms is cooled and routed to the vent gas scrubber for use as wash water. The tert-butanol tower concentrates tert-butanol in the overhead to about 80 wt% or higher, such as about 85 wt% or higher. Oxygenated compounds lighter than tert- butanol (e.g., methanol, ethanol, acetone, and MEK) are concentrated in the overhead so that they can be purged. The overhead is condensed and refluxed back to the tower with the overhead product being withdrawn as a vapor distillate which can be sent to fuel gas or flare. Part of the tert-butanol and water stream from the bottom is pumped back to the tert-butanol tower as reflux with the remainder being withdrawn as liquid distillate. The tert-butanol distillate is recycled to the rich stage emulsion circulation circuit. [0103] In alternative embodiments, acid extraction can be performed by a butene feed treated with 60 wt% to 65 wt% sulfuric acid (e.g., by first indirectly heating the acid in a heat exchanger). Steam can be introduced into the acid extract soon prior to introduction of the acid extract into a heat exchanger, and the amount of unwanted polymer formation can be reduced. For example, by maintaining the amount of steam injected within a range of about 0.5 pound per pound of reacted butenes, the polymer formation can be kept at substantially negligible levels. Where more than 1 pound per pound of stream is used, the amount of tert-butanol formed beging to increase, and thus the net recovery of isobutylene as the free olefin is reduced. Nonetheless, tert-butanol that does form can be separated from the isobutylene and introduced to a dehydration process of the present disclosure. [0104] As an example, butene feed is introduced into an extractor and introduced with about 60 to about 65 weight percent sulfuric acid. The acid and butenes mixture are mixed at a temperature of about 20 ^oF to about 130 ^oF for about 30 minutes to about 60 minutes. The mixture is then removed from the extractor and introduced to a separator. The isobutylene reacts with the acid to form a sulfuric acid extract whereas the remainder of the olefins and paraffinic isomers of isobutylene are removed as a raffinate phase. The sulfuric acid extract containing about 15 wt% to about 40 wt% isobutylene is removed from a settler and passed to a heater, where the sulfuric acid is raised to a temperature of about 275 ^oF to about 325 ^oF in order to thermally separate the isobutylene from reaction with the acid. Residence time is low, such as about 0.01 second. Immediately prior to introduction of the sulfuric acid into the heater, steam is added in amounts of 0.5 to 1 pound of steam per pound of isobutylene in the sulfuric acid phase. The conditions within the heater are controlled such that the concentration of the acid in the effluent from the heater is maintained within a desired range, for example, about 60 wt% to about 65 wt%. The steam added to the system and the released isobutylene are passed from the heater in the vapor phase, while the acid is in the liquid phase. The mixed phase effluent is passed to a settler. The steam and isobutylene phase, containing some t-butyl alcohol, is passed overhead through a condenser and into a settler. Isobutylene is passed overhead while polymer is removed as a top liquid layer. The alcohol and water phase may be recycled for vaporization and admixture with the sulfuric acid. Additional steam may be added if necessary to make up for losses from the system. [0105] In alternative embodiments, a butene feed is introduced with about 55 wt% to about 70 wt% of sulfuric acid, and isobutylene is regenerated by steam distillation of the sulfuric acid extract where the regeneration process is performed slowly to reduce or prevent foaming and reduce or prevent acid spill over with the isobutylene. For example, during the steam stripping, introduction of a hydrocarbon oil alone or in admixture with an alcohol, can reduce or eliminate foaming. Steam can include 1 vol% to about 2 vol% of tert-butyl alcohol about 3 vol% to about 4 vol% oil. Oil can be any suitable oil having a boiling point of about 400 ^oF to about 900 ^oF, such as about 500 ^oF to about 800 ^oF, such as clay treated oil. As an example, a butene feed containing isobutylene is passed into a reactor with sulfuric acid of 55-75 wt%. The emulsion obtained in the reactor is then passed to a settler to remove unreacted hydrocarbons. The sulfuric acid extract is passed from the settler to a vent drum from which normal butylene are removed, and the residual acid extract containing isobutylene is then passed into a regenerator. Oil is passed from an oil storage tank to the regenerator. Steam is introduced into the regenerator, and isobutylene is distilled overhead, the spent sulfuric acid being removed to acid reconcentrator from which oil and vapors are removed overhead. Reconcentrated sulfuric acid is removed from the concentrator. [0106] In alternative embodiments, a butene stream is passed into an adsorption zone at a rate of about 0.3 to about 10 W/Hr/W and contacted in the vapor phase at about 40 ^oF to about 80 ^oF with an adsorbent that is a crystalline metallic aluminosilicate having pore openings of about 5 Angstrom diameter, and recovering an isobutylene stream stream that substantially or completely free of normal butenes. The adsorbent, if pelleted, can having a binding material made of catalytic inert materials such as calcined bentonite. Clay binders do not work well. In addition, tempratures of 250 ^oF to 400 ^oF can cause rapid polymerization, which is undesirable in feeds to butyl rubber polymerizations. Zeolites suitable as adsorbents include chabasites and various synthetic zeolites. In some embodiments, a zeolite is a base-exchanged Na₂OAl₂O₃2SiO₂nH₂O which has pore openings of about 5 angstrom diameter. As an example, a butene feed is treated with sulfuric acid (such as about 65 wt% sulfuric acid) to form an isobutylene product that is passed to a cooler where the isobutylene product is cooled to about 40 ^oF to about 80 ^oF and then passed to a zeolite treating vessel. In the zeolite treating vessel, the isobutylene product is contacted at a rate of about 0.3 W/Hr/W to about 10 W/Hr/W at atmospheric pressure with the zoelite. The zeolite may be arranged on trays or packed on supports or unsupported. The zeolite removes water and straight chain hydrocarbons, including butene-1, from the isobutylene product. The isobutylene product may then be transferred from the zeolite treating vessel to a simple distillation zone to remove traces of polymer and branched chain C₅₊ hydrocarbons. The resulting overhead product contains isobutylene of purity of about 99.9% or greater. Isoprene [0107] In some embodiments, highly pure isobutylene formed from one or more processes described above is used to form isoprene, which can be used as a comonomer to make butyl rubber, such as butyl rubber that is substantially or entirely bio-based. For example, butenes can be converted to bio-based C₅ olefins by, for example by hydroformylation by reacting butenes (e.g., isobutylene) with formaldehyde (which can be bio-based formaldehyde, e.g., prepared from methanol produced from biomass by thermochemical processes) or CO and H₂, in the presence of an acidic catalyst (e.g., via the Prins reaction of isobutylene and formaldehyde) to form isoprene. Alternatively, bio-based pentenes, hexenes and higher molecular weight olefins can also be prepared as co-products from the metathesis of ethylene and butenes (e.g., by the disproportionation of isobutylene and 1-butene to form ethylene and methylpentene(s), the disproportionation of 2 equivalents of isobutylene to form dimethylbutene(s), etc.). By varying the relative amounts of ethylene and the various butene isomers fed to the metathesis reaction and the metathesis reaction conditions (e.g., temperature, pressure, catalyst, residence time, etc., the metathesis product stream can be accordingly adjusted to provide desired amounts of C₅ and higher olefins. In particular, higher concentrations of isobutylene and/or 1-butene in the metathesis feedstock would favor higher levels of C₅ and higher molecular weight olefins. C₅ olefins (e.g., isopentene, 3-methyl-1-butene and 2-methyl-2-butene, etc.) can then be converted to, e.g., isoprene using a dehydrogenation catalyst. Butyl Polymers and components thereof [0108] Butyl polymers of the present disclosure can be copolymers having isoolefin (isobutylene) derived content in the copolymer in a range of about 70 wt% to about 99.5 wt% of the total monomer derived units in one embodiment, such as about 85 wt% to about 99.5 wt%. The total multiolefin derived content in the copolymer is present in the range of mixture from about 0.5 wt% to about 30 wt%, such as about 0.5 wt% to about 15 wt%, such as about 0.5 wt% to about 12 wt%, such as about 0.5 wt% to about 8 wt%. Herein for the purpose of the present disclosure, multiolefin refers to any monomer having two or more double bonds. In at least one embodiment, the multiolefin is any monomer comprising two conjugated double bonds (e.g., isoprene). In some embodiments, the multiolefin may be an aromatic monomer (e.g. para-methylstyrene). Halogenated butyl rubber, polyisobutylene (no comonomer), and specialty elastomers, such as star-branched butyl rubber are also included in the scope of the present disclosure. [0109] Butyl polymers of the present disclosure can provide sustainability credits through certified chain-of-custody mass balance approaches (tying bio-based feedstocks to final products), through analytical methods, such as carbon isotope measurement, or through a combination of both. Butyl polymers of the present disclosure can provide sustainability credits, e.g., as verified by mass attribution, such as International Sustainability & Carbon Certification (ISCC) (based on the process of making the butyl rubber and monomers thereof). In particular, ISCC has been designed to trace the flow of materials through a complex value chain. Since chemically recycled or bio-based feedstocks are typically blended in the manufacturing complex, physical segregation of recycled content is often practically and economically very difficult. A mass balance approach makes it possible to track the amount and sustainability characteristics of circular and/or bio-based material in the value chain and attribute it based on verifiable processes used to make the polymers. In some embodiments of the present disclosure, all or substantially all of the isoolefin (about 70 wt% to about 99.5 wt% of the butyl rubber) can be bio-based. In addition, all or substantially all of the multiolefin (about 0.5 wt% to about 30 wt% of the butyl rubber) can be bio-based. [0110] The multiolefin used in butyl polymers of the present disclosure can be a C₄ to C₁₄ multiolefin such as isoprene, butadiene, 2,3-dimethyl-1,3-butadiene, myrcene, 6,6-dimethyl-fulvene, hexadiene, cyclopentadiene, alkylstyrene, and piperylene, and the like. [0111] Other C₄ to C₇ isoolefin derived unit-containing polymers suitable for use in the present disclosure include terpolymers comprising the isoolefin and two multiolefins wherein the multiolefins have different backbone structures prior to polymerization. Such terpolymers include both block and random terpolymers of C₄ to C₈ isoolefin derived units, C₄ to C₁₄ multiolefin derived units, and alkylstyrene derived units. One such terpolymer may be formed from isobutylene, isoprene, and alkylstyrene, such as methylstyrene, monomers. Another suitable terpolymer may be polymerized from isobutylene, cyclopentadiene, and alkylstyrene monomers. Such terpolymers are obtained under cationic polymerization conditions. [0112] Thus, polymers useful herein can be described as copolymers of a C₄ isomonoolefin derived unit, such as an isobutylene derived unit, and at least one other polymerizable unit with non limiting examples of isobutylene-based elastomers including poly(isobutylene), butyl rubber (isobutylene-isoprene rubber, "IIR"), branched ("starbranched") butyl rubber, star-branched polyisobutylene rubber, block terpolymers of isoprene-isobutylene-styrene, random copolymers of isobutylene and para-methylstyrene, and random terpolymers of isobutylene, isoprene, and paramethyl styrene. Chlorinated, brominated, and other functionalized derivatives of such polymers are also within the scope of the present disclosure. [0113] In some embodiments, the butyl rubber is an isobutylene based elastomer obtained by reacting about 92 wt% to about 99.5 wt % of isobutylene with about 0.5 wt% to 8 wt% isoprene, or about 95 wt% to 99.5 wt% isobutylene with about 0.5 wt% to about 5.0 wt% isoprene. Such copolymers derived from isobutylene and isoprene are commonly reffered to as butyl rubbers. In some embodiments, the butyl rubber is about 10 wt% or greater derived from bio-based monomers, such as about 25 wt% or greater, such as about 50 wt% or greater, such as about 75 wt% or greater, such as about 90 wt% or greater, such as about 95 wt% or greater, such as about 10 wt% to about 100 wt%, such as about 50 wt% to about 100 wt%, such as about 75 wt% to about 100 wt%, such as about 90 wt% to about 100 wt%, such as about 95 wt% to about 100 wt%, such as about 98 wt% to about 100 wt%, such as about 100 wt%, alternatively about 95 wt% to about 98 wt%. For example, commercial butyl polymers contain additives, such as about 2 wt% inorganic bromine, 2.3wt% calcium stearate, and 1.3wt% epoxidized soybean oil. The resulting isobutylene content is about 92.5wt%. In some embodiments, the calcium stearate and oil can be derived from bio-based feedstocks. [0114] As discussed above, high purity isobutylene (typically about 99.5 wt% to about 100 wt%) and isoprene (such as about 98 wt % to about 99.9 wt %) can be used for the manufacture of butyl rubber of the present disclosure. Impurities can have an impact on isobutylene/isoprene conversion, polymer molecular weight distribution, and reactor performance. The monomer purity is controlled by purchase specifications and stringent quality control with additional purification completed at the production unit if desired. High purity isobutylene can be derived from fossil fuels, advanced recycling processes, or bio based sources. [0115] In some embodiments, butyl rubber of the present disclosure can have a weight average molecular weight (M_w), as determined by gel permeation chromatography (GPC), of about 380 kDa to about 2,000 kDa, such as about 390 kDa to about 1,000 kDa, such as about 400 kDa to about 850 kDa, such as about 425 kDa to about 750 kDa, such as about 450 kDa to about 650 kDa. In some embodiments, butyl rubber of the present disclosure can have a number average molecular weight (M_n), as determined by gel permeation chromatography (GPC), of about 5 kDa to about 500 kDa, such as about 80 kDa to about 250 kDa. In some embodiments, elastomers of the present disclosure can be characterized by a narrow molecular weight distribution (MWD) determined by Mw/Mn (weight average molecular weight divided by number average molecular weight), as determined by gel permeation chromatography, such as about 1.01 to about 5, such as about 2 to about 5, such as about 2.5 to about 4.5. Butyl Rubber Processes [0116] The above polymers may be produced by any suitable polymerization. The polymers can be produced in either a slurry polymerization process or a solution polymerization process. If the polymer is produced in a slurry polymerization process where the polymer precipitates out of the reaction medium, then the polymer is dissolved into a suitable solvent, e.g., the creation of a polymer cement, prior to halogenation. For polymers produced via a solution process, after removal of unreacted monomers and removal or neutralization of unused catalysts, the same polymer containing solution, or polymer cement, may be used for halogenation. The polymer cement can contain about 1 wt % to about 70 wt % polymer, such as about 10 wt % to about 60 wt % polymer, such as about 10 wt % to about 50 wt % polymer, such as about 10 wt % to about 40 wt % polymer. Catalyst Preparation [0117] The high purity diluent (typically about 98 wt% to about 100 wt%) used for catalyst diluent from a diluent recovery tower is combined with the initiator and then the catalyst. The initiator is typically HCl or water, the catalyst is typically either aluminum alkyl catalyst or aluminum chloride catalyst. When an aluminum alkyl catalyst is used, the catalyst diluent and catalyst are combined and mixed with static mixers to ensure good distribution. When aluminum chloride catalyst is used, the catalyst diluent stream is split and one portion of the catalyst diluent is chilled and sent through aluminum chloride dissolving bed(s) and subsequently recombined with the other portion of the catalyst diluent to achieve the desired catalyst concentration. The catalyst/diluent/initiator stream is injected into reactor(s) at a high velocity to ensure good distribution in the reactor, such as about 1.5 m/s to about 5 m/s. The catalyst to initiator ratio can be about 1 mol/mol to about 5 mol/mol, such as about 1.5 to about 2.5 mol/mol. [0001] The reaction is sensitive to oxygenated compounds, oxygen and moisture. Moisture can be removed from fresh isoprene and isobutylene before being sent to the reactor. A diluent/monomer recycle stream is dried with fixed bed alumina and/or molecular sieve driers to remove residual moisture and oxygenated compounds. The recycled solvent stream is dried with fixed bed molecular sieve driers or by fractionation before reuse in the process. The recycle streams and raw material streams are fitted with moisture analyzers, oxygen analyzers, and oxygenate analyzers to assure moisture, oxygen and oxygenate levels are controlled. Light ends including oxygen are purged from the diluent recovery tower distillate drum. Feed Blend and Reactors [0118] Isobutylene and isoprene in diluent are prepared to a predetermined composition in a feed blend drum, chilled to about -90 ^oC to about -100 ^oC using a series of heat exchangers and fed to the reactor(s). A catalyst and co-catalyst are prepared in high purity diluent and fed to the reactor(s). A copolymer of isobutylene and isoprene is made in the reactor(s). An example diluent used is methyl chloride. In some embodiments, the feed blend contains about 20 wt % to about 40 wt % isobutylene and about 0.4 wt % to about 1.4 wt % isoprene depending on the grade with the remainder being mainly diluent. [0119] Butyl reactors foul with time and are taken out of service periodically to be cleaned. The butyl reaction process can thus be a semi batch process with a number of reactors producing and a number of reactors in non-production mode. At the end of the production cycle the producing reactor is quenched by injecting alcohol or water into the reactor to stop the reaction and then flushed with diluent at a temperature of about -40 ^oC to about -80 ^oC to remove the bulk of the rubber slurry and gradually warm the reactor. Solvent is introduced to further warm the reactor up to 0 ^oC to about 50 ^oC. The reactor is then washed with solvent at a temperature of about 0 ^oC to about 90 ^oC to remove the rubber foulant that has accumulated on the vessel surface. When the reactor is clean, the solvent is displaced with diluent at about -40 ^oC to about -80 ^oC to gradually cool the reactor down and then chilled down to about -90 ^oC to about -100 ^oC in preparation for production. The flowrates, temperatures, and duration of each of the non-production stages are managed to ensure the mechanical design conditions of the reactor and reactor pump are not compromised. [0120] When the reactor is chilled for production, the reactor is primed with a mixture of diluent, isobutylene, and isoprene. The diluent isobutylene and isoprene concentrations are set to emulate the normal background concentrations during reactor production to ensure the polymer is quickly at specification. The initiator and co-initiator are then injected at high rates to ensure the reaction initiates rapidly before being set to normal rates to assure the rubber is at specification. Solvent Replacement Process [0121] An alcohol or water quench is injected into the reactor overflow outlet to quench the catalyst, e.g., as described in U.S. 4,154,924 incorporated by reference herein. Quench may be premixed with polar diluent and may then be diluted with solvent, with or without a static mixer, before adding to the reactor outlet. The quench is injected and mixed with the reactor slurry with or without a mechanical mixer. The resulting stream is then routed to a solution drum where solvent vapor is added to heat the process and dissolve the polymer to make a polymer/solvent solution known as cement. A typical solvent is a mixture of normal hexane and isomers of hexane. The solution drum liquid outlet is then routed to a surge drum. The solution drum and surge drum may be combined into a single drum. The solution may be sampled and analyzed periodically to monitor polymer properties. Statistical Process Control techniques and fundamental or empirical models may be used to monitor product quality and guide optimization of polymerization conditions. The drum(s) operating temperatures can be about -20 ^oC to about +30 ^oC, such as about -20 ^oC to about +10 ^oC and the operating pressures can be about 0 kPag to about1000 kPag, such as about 0 kPag to about 500 kPag. The process is operated to generate a vapor stream of about 0 % to about 30% of the total drum feed, e.g., as described in U.S. Patent No.3,257,349 incorporated by reference herein. The liquid stream from these drums having cement/solvent/diluent/unreacted monomers is routed to a cement stripping tower. The vapor stream having solvent/diluent/unreacted monomers from, for example, the drums is routed to either a cement stripping tower or cement stripping tower overheads. The cement stripping tower can be a 20-60, such as 40-60, dual flow tray suitable for fouling service, for example the TECHNIP RIPPLE TRAY^TM tower, e.g., as described in U.S.3,257,349. Solvent vapor is injected at the bottom of the tower and flows counter currently to the cement. The cement stripping tower overheads having diluent, unreacted monomers, and a portion of the solvent is routed to a solvent recovery tower where high purity solvent is recovered in the bottoms stream for recycle and diluent, unreacted monomers are recovered in the overheads and sent to the diluent recycle stream driers. [0122] The cement stripping tower is operated to ensure that the monomer concentration is very low in the cement stream as any monomers could react in subsequent halogenation processes and exceed desired product specifications (e.g., Industrial Hygiene control). The monomer concentration in the cement stream is < 200 wtppm and typically < 50 wtppm for good industrial hygiene control. [0123] The bottoms cement stream from the cement stripping tower is flashed into 1-2 cement concentrator drums. The cement is cooled and the cement concentration increased. The cement concentrator overheads vapor stream has a temperature that is determined by the utilities temperature, typically cooling water or air. The operating pressure of the concentrator drum(s) is determined by the solvent vapor pressure curve, the typical solvent is a mixture of normal hexane and isomers of hexane. The cement concentrator(s) are operated at an absolute pressures of about 40 kPaa to about 150 kPaa, such as about 50 kPaa to about 100 kPaa, e.g., as described in U.S. Patent No.3,257,349. The cement concentrator drum is fitted with side to side trays or baffle plates (shower deck) that allow the solvent vapor to separate from the viscous cement and minimize vapor entrainment in the bottoms cement stream. The overheads solvent from the cement concentrator is recycled in the process. The bottoms cement stream is sent to storage. The cement concentration sent to storage is about 18 wt % to about 30 wt %, such as about 22 wt % to about 28 wt%. Heat integration is used extensively in the solvent recovery part of the plant and the reslurry part of the unit to maximize energy efficiency. [0124] Alternatively to a solvent replacement process, wet butyl rubber crumbs and/or bales of dry finished butyl rubber are chopped or ground to small pieces and conveyed to a series of agitated dissolving vessels or to a large vessel divided into multiple stages. Solutions containing 15–20% polymer can be prepared in 1–4 h depending upon temperature, particle size, and agitation. This method has the advantage of being independent from the butyl polymerization process but involves storage and careful inventory control between the two stages of the process. This process also involves two finishing operations: one to produce the butyl backbone, the second to finish the halobutyl product. Halogenation and Neutralization [0125] In some embodiments, the butyl rubber is halogenated (and neutralized). Halogenation and neutralization of cement to form halobutyl rubber can be performed using any suitable process. The cement is pumped to a well-mixed halogenation reactor where halogen (e.g., Br₂, Cl₂, NaBr, NaCl, or combinations thereof) is added to form halobutyl rubber. The halogen can be vapor chlorine or liquid bromine depending on the grade of halobutyl being made. The halogenation reactor can be a CSTR (continuous stirred tank reactor) or a high speed mixing device such as a CONTACTOR^TM from STRATCO^TM. In some embodiments, reactor vessel is a mixed flow stirred tank, a conventional stirred tank, a packed tower, or a pipe with sufficient flow and residence time to permit the desired reaction to occur. Additional pipework and valves may be included downstream to control reaction residence time. Structure III stabilizer is introduced at any suitable portion of halogenation process, such as cement tank, pump, or halogenation reactor. [0126] The halogenated cement and reaction by-products are then mixed with a neutralizing agent (such as sodium hydroxide) in a first neutralization unit to neutralize the resultant HCl or HBr/bromine. The first neutralization stage may be 1-4 individual process units and may be a CSTR, a CONTACTOR^TM, a static mixer, or a combination thereof. The stream from the first neutralization unit is then mixed with an additive in a second neutralization unit to complete neutralization and to form a stable emulsion. The additive is typically calcium stearate dispersion with a surfactant. In some embodiments, a surfactant is a non-ionic alcohol ethoxylate, such as ethoxy tridecyl alcohol. The second stage neutralization process unit may be 1-4 individual process units and may be a CSTR, a CONTACTOR^TM, a static mixer, or a combination thereof. [0127] The water/hydrocarbon emulsion from the halogenation and neutralization section is routed to a flash drum and stripper vessels to remove and recover the solvent. The water/hydrocarbon emulsion is flashed into an agitated flash drum where steam is injected into the liquid to strip the solvent from the stream. A rubber crumb is formed in the flash drum, an additive is added to the flash drum to prevent polymer agglomeration and vessel plugging. The additive is typically calcium stearate dispersion with a surfactant. The water/crumb mixture flows to an agitated stripper where additional residence time and reduced pressure allows the solvent to diffuse from the crumb to the vapor stream. Additional steam may be injected into the stripper to aid the solvent diffusion process. Water is sprayed into the vapor space of the flash drum and the vapor space of the stripper to reduce vessel fouling and provide cooling, the spray pattern is typically either hollow cone or solid cone. The slurry concentration to the flash drum and stripper process units is controlled to minimize agglomeration and the propensity for plugging by, for example, controlling flow rates of the calcium and surfactant injected into the flash drums to manage the crumb size within a desirable operational parameter. Lower injection rate provides higher crumb size and vice versa [0128] The solvent/water in the vapor streams from the flash drums is condensed and the solvent separated in a condenser/separator and sent to storage for subsequent drying and recycle, the water is recycled in the process. [0129] During halobutyl production, the cement temperature to halogenation is controlled to less than 65 ^oC, such as about 20 ^oC to less than 65 ^oC, or about 40 ^oC to about 60 ^oC, to ensure favorable reaction to meet final product cure properties. [0130] The flash drum is operated at an absolute pressure of about 140 kPaa to about 190 kPaa, and the liquid temperature is about 105 ^oC to about 120 ^oC. The stripper pressure can operate at a pressure of about 80 kPaa to about 130 kPaa, such as about 90 kPaa to about 120 kPaa, and the liquid temperature is about 90 ^oC to about 110 ^oC. The stripper pressure is controlled by vacuum pumps or vacuum jets. The stripper overheads stream is recycled to the flash drum(s) for energy conservation. In larger production facilities multiple flash drum(s) and stripper(s) may be operated in parallel. In facilities where parallel flash drum(s) and stripper(s) are employed, instrumentation can be used to ensure even flow distribution between the parallel units. [0131] Flash drum can have agitators to ensure good mixing between cement and water and to promote crumb formation such as eccentric flat blade agitators. Stripper agitators to ensure good mixing of floating rubber particles in liquid include up or down pumping pitched blade turbines, up or downpumping hydrofoils. [0132] The crumb size can be controlled in the flash drum and stripper, because too small crumbs results in vessel and pipework fouling and difficulty dewatering/drying, whereas too large crumbs makes solvent removal difficult and may result in pipework plugging. Crumb size is controlled by calcium stearate addition, calcium stearate particle size and particle size distribution, and surfactants added with the calcium stearate. Crumb size distribution is measured and monitored, e.g., depending on downstream processing such as extruder sizing. [0133] In some embodiments of a halogenation process, isobutylene-based polymers having unsaturation in the polymer backbone, such as isobutylene-isoprene polymers, may be halogenated using an ionic mechanism during contact of the polymer with a halogen source, e.g., molecular bromine or chlorine, and at temperatures of from about 20° C to about 80° C Isobutylene based polymers having no unsaturation in the polymer backbone, such as isobutylene-alkylstyrene polymers, can undergo halogenation under free radical halogenation conditions, e.g., in the presence of white actinic light or by inclusion of an organic free radical initiator in the reaction mixture, and at temperatures of about 20° C to about 90° C. [0134] In some embodiments, a halogenation process of the present disclosure is a regenerative halogenation process. Conventional regenerative halogenation processes can occur by contacting a polymer solution with a halogenating agent and an emulsion containing an oxidizing agent. The oxidizing agent interacts with hydrogen halide created during halogenation, converting the halogen back into a form useful for further halogenation of the polymer thereby improving the halogen utilization. [0135] For regenerative halogenation, an emulsion is fed per feedstream into the halogenation reactor . The emulsion includes the oxidizing agent, water, solvent, and an emulsifying agent, such as a surfactant. The emulsion is prepared by providing about 10 wt % to about 80 wt %, such as a 20 wt % to about 70 wt % or about 25 wt % to about 45 wt %, solution of the oxidizing agent in water and mixing this with a solvent and an emulsifying agent under suitable mixing conditions to form a stable emulsion. The emulsion may be achieved by mixing the aqueous phase into the emulsifying agent containing solvent, or by mixing the oxidizing agent with the emulsifying agent first and then combining with the solvent. The amount of oxidizing agent can be about 0.1 to 3, such as about 0.25 to about 3, such as about 0.5 to about 3 moles of active oxidizing agent per mole of halogenating agent. Use of an oxidizing agent during bromination increases bromine utilization to about 70 to 85%. [0136] Oxidizing agents useful in a process of the present disclosure are materials which contain oxygen, such as water soluble oxygen containing agents. Suitable agents include peroxides and peroxide forming substances such as hydrogen peroxide, organic hydrogen peroxide, sodium chlorate, sodium bromate, sodium hypochlorite or bromite, oxygen, oxides of nitrogen, ozone, urea peroxidate, acids such as pertitanic perzirconic, perchromic, permolybdic, pertungstic, perunanic, perboric, perphosphoric, perpyrophosphoric, persulfates, perchloric, perchlorate and periodic acids. Of the foregoing, hydrogen peroxide and hydrogen peroxide-forming compounds, e.g., per-acids and sodium peroxide, have been found to be highly suitable for carrying out halogen regeneration. [0137] The choice of solvent for the emulsion may be any solvent suitable for use or used in forming the polymer cement. In one embodiment, the solvent is selected to be the same solvent used to form the polymer cement. Suitable solvents include a paraffinic hydrocarbon or a halogenated hydrocarbon, such as pentane, hexane, heptane, and the like, as mono-, di-, or tri-halogenated C₁ to C₆ paraffinic hydrocarbon or a halogenated aromatic hydrocarbon such as methyl chloride, methylene chloride, ethyl chloride, ethyl bromide, dichloroethane, n-butyl chloride, and monochlorobenzene or mixtures of the hydrocarbon and inert halo-hydrocarbon solvent. Furthermore, the solvent may be a combination of the solvents provided herein, including isomers thereof. [0138] The emulsion fed via feedstream may be introduced into the halogenation reactor at the beginning of the halogenation cycle or after consumption of the halogen via halogenation of the polymer has begun. The halogenation reaction and the halogen regeneration reaction can occur at a temperature of about 20 °C to about 90 °C for a time sufficient to complete halogenation of the polymer. When molecular bromine is the halogenating agent introduced via feed stream (line), bromine consumption is indicated by a color change of the reaction mixture from a reddish brown to a light tan or amber color. Following sufficient reaction time in the halogenation reactor, the effluent, exiting the halogenation reactor, is neutralized, e.g., as described above. Structure III stabilizers [0139] A free-radical stabilizer, free-radical scavenger, or antioxidant, collectively referred to herein as a “structure III stabilizer”, is provided at a location upstream of the halogenation reactor. The structure III stabilizer may be organic-soluble or a water compatible compound, such as an oil- soluble compound or a hexane-soluble compound. [0140] Suitable structure III stabilizers include sterically hindered nitroxyl ethers, sterically hindered nitroxyl radicals, butylated hydroxytoluene (BHT), hydroxyhydrocinnamite, thiodipropinoate, phosphites, and combinations thereof. [0141] Commercially available examples of structure III stabilizers that can be added during the preparation of halobutyl rubbers of the present disclosure include, but are not limited to, TEMPO, Tinuvin™ NOR 371, Irganox PS 800, Irganox 1035, Irganox 1010, Irganox 1076, Irgafos 168. TEMPO is a term generally used to refer to (2,2,6,6-tetramethylpiperidin-1-yl)oxy. The sterically hindered nitroxyl radical may be TEMPO. Tinuvin™ NOR 371 may be used which is a high molecular weight hindered amine NOR stabilizer, commercially available from BASF as a plastic additive. Irganox PS 800 may be used, which is commercially available from CIBA and is the trade name of didodecyl-3,3′-thiodipropionate. Irganox 1035 may be used and is commercially available from CIBA/BASF and is the trade name of thiodiethylene bis(3,5-di-tert-butyl-4- hydroxyhydrocinnamate). Irganox 1010 may be used which is commercially available from BASF and is the trade name of pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate). Irganox 1076 may be used which is commercially available from CIBA and is the trade name of octadecyl-3-(3,5-di-tert.butyl-4-hydroxyphenyl)-propionate. Sterically hindered phenolics may include BHT, Irganox PS 800, Irganox 1035, or combinations thereof. Irgafos 168 may be used which is commercially available from BASF and is a general purpose phosphite. In some embodiments, other structure III stabilizers may be added to the bromobutyl-rubber of the present disclosure including, but not limited to, light stabilizers and UV-absorbers. [0142] In an embodiment, the structure III stabilizer may be added in more than one location in the halogenation process. [0143] In some embodiments, the total amount of structure III stabilizer to be added during the process of preparing the halobutyl rubber is greater than or about 20 ppm, such as greater than 50 ppm, such as greater than 75 ppm, such as greater than 100 ppm, to less than or about 500 ppm, such as less than or about 400 ppm, such as less than or about 300 ppm, such as less than or about 200 ppm, such as less than or about 150 ppm, such as less than or about 100 ppm. The ppm weight basis is the weight relative to the halobutyl rubber (whether in solution, slurry, or recovered). Finishing [0144] The bottoms stream from the stripper(s) containing rubber crumb and water is routed to an agitated slurry tank. Typically pitched blade impellors or a combination of pitched blade impellors and flat blade impellors in up or downpumping mode are used. [0145] The rubber crumb/water slurry is pumped to a dewatering screen(s) to remove gross water. The rubber crumb is then fed to 2-3 extruders in series to dewatering extruder and drying extruder the rubber crumb. The dewatering/first stage drying extruders may be one or more of the following: expanders, expellers, dewatering extruders, slurry dewatering units, volatiles control unit. The final stage drying extruders may be dual worm drying extruders, e.g., as described in U.S. Patent No. 7,858,735 incorporated by reference herein. The temperatures and pressures in the extruders are controlled by adjusting the restriction at the extruder outlet typically with a fixed or variable die plate. Heat may be added by steam jacketing the extruders. Inert gas may be injected to improve drying, as described in U.S. Patent No. 4,508,592 incorporated herein by reference. Polymer additives are injected at various stages of the extrusion process to meet product specifications and depending on the grade may consist of none, one, or more of the following polymer additives: epoxidized soy bean oil, calcium stearate butylated hydroxytoluene, Irganox, or antioxidants. [0146] The crumbs from the final drying extruder are then transported to a fluidized bed conveyor for drying to product specification, the rubber crumb may be transported by mechanical conveyors. In some embodiments, the fluidized bed conveyor has 2 sections consisting of a primary hot section for drying the crumbs and secondary cool section to cool the crumbs. The crumbs from the fluidized bed conveyor are then routed to a packaging unit where the crumb is compacted into bales, packaged and quality checked. The final rubber polymer product is stored in warehouse for distribution to customers. Large production facilities operate multiple extrusion and fluidized bed drying lines in parallel. The solvent vapors from the slurry tank, the extruders and fluidized bed conveyors may be captured in an air collection system for treatment. [0147] Rubber fines are removed from finishing water recovered from the dewatering screens and extruders for recycle or disposal. The finishing water with fines removed is recycled to the reslurry and halogenation unit with excess water purged from the process. The excess water will be further treated at the facility before final disposal. Additional antifouling and additives may be added to the recycled water to reduce fouling and control pH. The additives may include but not exclusively none, one or more of: calcium chloride, proprietary antifoulants, e.g., PETROFLO^TM or borate based buffers. [0148] For some embodiments involving halogen regeneration, additives, including epoxidized soybean oil (also referred to as ESBO) and calcium stearate, may be added during the regenerative process. For example, ESBO may be added in the range of about 1 to about 2 phr in drying extruder before or during the drying. Additionally or alternatively, as described above, calcium stearate may be added to the cement to the second neutralization unit, and/or may be added to the flash drum to help the polymer from sticking to the equipment and to control the rubber particle size in the water slurry, and/or may be added to drying extruder during the drying. [0149] In some embodiments, an additive, such as ESBO, may be added to the stripper. Recycle Stream Driers [0150] The diluent/monomers recycle stream from the solvent replacement process section is dried using a combination of fixed bed alumina and chloride resistant molecular sieve driers to remove moisture. The alumina driers will also remove oxygenates. The alumina and molecular sieve driers may be operated in series or in parallel or a combination of both, for example the operation is parallel molecular sieve driers with an alumina drier in series. The fixed bed alumina and chloride resistant molecular sieve driers are taken out of service for regeneration when their water hold up capacity or oxygenate hold up capacity has been reached. The regeneration can include 1-3 depressurizations to deep vacuum to recover the hydrocarbon from the bed. The regeneration can include 1-3 warm pressurizations and depressurizations to maximize hydrocarbon removal before full regeneration. The regeneration can be carried out at about 240 ^oC to about 300 ^oC for molecular sieve driers and 190 ^oC to 250 ^oC for alumina driers. The regeneration gas humidity can be controlled by cooling the stream and removing moisture with refrigerated heat exchangers in advance of heating. The regeneration will include a steaming stage to minimize oil make up from the process for molecular sieves. Recovery and Recycle of Monomers from Isobutylene-based Polymers Using Distillation Processes [0151] The diluent/monomers stream is sent to recycle towers to separate and recover diluent and monomers for reuse in the process. For example, a first recycle tower may be a single tower or 2 separate towers. The first recycle tower(s) recover diluent and isobutylene in the overheads stream. The overheads stream is split with a portion sent to a diluent recovery tower where high purity diluent is recovered for use as catalyst diluent and a portion sent for recycle. The bottoms of the diluent recovery tower is combined with the other portion of the recycle tower overheads and recycled to feed blend. The bottoms of the first recycle tower is sent to a second recycle tower. Overheads of the second recycle tower are sent to diluent recovery tower. Bottoms of the second recycle tower containing isobutylene, isoprene, and some heavies is sent to an isobutylene recovery tower where isobutylene is recovered overhead for recycle. The bottoms of the isobutylene recovery tower is sent to an isoprene recovery tower where isoprene is recovered overhead for recycle. The bottoms of the isoprene recovery tower is purged from the process. The isobutylene and the isoprene recovery tower may be combined into a single distillation column. The distillate drum on the diluent recovery tower can have an inerts venting system. This inerts venting system recovers diluent from the inerts stream and vents the residual ethylene/ethane by product from the aluminum alkyl catalyst and inerts from the process. The inerts recovery system has a distillation tower or a series of refrigeration heat exchangers to recover diluent. [0152] Antifoulants are injected into the isobutylene recovery tower and isoprene recovery tower to minimize fouling. Antifoulants may include a structure III stabilizer of the present disclosure and/or one or more suitable other antioxidants or antifoulants, including but not exclusively BHT (butylated hydroxytoluene) and proprietary antifoulants, e.g., PETROFLO^TM. The isoprene recovery tower trays may be electropolished to minimize fouling. Oxygen analyzers are fitted in the second recycle tower overhead and diluent recovery tower overhead. [0153] In some embodiments, concentration of isobutylene in the diluent recovery tower overheads used for catalyst diluent is < 50 wtppm isobutylene and such as < 20 wtppm isobutylene. The recycle tower/diluent recovery tower temperatures can be set by the utilities temperature on the overhead condensers, typically cooling water or air. The tower pressures are set by the stream compositions based on the vapor pressure curves at the tower operating temperature. The second recycle tower pressure can be about 800 kPag to about 1200 kPag, such as about 1000 kPag to about 1200 kPag. The diluent recovery tower operating pressures can be about 800 kPag to about 1200 kPag, such as about 1000 kPag to about 1200 kPag. The isobutylene recovery tower 520 can use refrigerant in an overhead condenser to set a tower operating pressure of about 150 kPag to about 250 kPag. The isoprene recovery tower can use refrigerant or cooling water in an overhead condenser and operates at a pressure of about 50 kPaa to about 150 kPaa to minimize fouling. The second recycle tower and isobutylene recovery tower can recover about 95% to about 99.999%, such as about 99.8 to about 99.9%, of the isobutylene in the feed. The isobutylene composition in the recycle streams is set by the reactor conversion. Physical Properties of Halobutyl Rubbers [0154] The physical and mechanical properties of halobutyl rubbers described herein can be incorporated into a typical inner liner formulation to determine the physical and mechanical properties of such materials. In some embodiments, halobutyl elastomers produced from methods detailed herein (after compounding) have an initial Modulus (as determined by ASTM D412) of about 9.5 MPa to about 10.3 MPa, such as about 9.6 MPa to about 10.2 MPa, such as about 9.7 MPa to about 10 MPa. In one or more embodiments, halobutyl elastomers of the present disclosure (after compounding) exhibit an initial elongation at break (as determined by ASTM D412) of about 775 % to about 825 %, such as about 785 % to about 815 %, such as about 800 % to about 810 %. In one or more embodiments, halobutyl elastomers of the present disclosure (after compounding) exhibit an initial tear strength (as determined by ASTM D624) of about 34.1 N/mm to about 37.5 N/mm, such as about 35 N/mm to about 37 N/mm, such as about 35 N/mm to about 36 N/mm. In one or more embodiments, halobutyl elastomers of the present disclosure (after compounding) exhibit an initial hardness value (as determined by ASTM D2240) of about 45 to about 46. Industrial Applicability [0155] The brominated elastomers disclosed herein can be used to make any number of articles. In certain embodiments, the article is selected from tire curing bladders, tire innerliners, tire innertubes, and air sleeves. In some embodiments, the article is a hose or a hose component in multilayer hoses, such as those that contain polyamide as one of the component layers. Other useful goods that can additionally or alternatively be made using polymers of the present disclosure include air spring bladders, seals, molded goods, cable housing, rubber-based pharmaceutical stoppers, and other articles disclosed in THE VANDERBILT RUBBER HANDBOOK, PP. 637-772 (Ohm, ed., R.T. Vanderbilt Company, Inc., 1990). [0156] Overall, processes of the present disclosure can produce bio-based isobutylene that is pure enough for the production of high molecular weight polymers (such as butyl rubber) and is scalable as industrial sized processes for bio-based isobutylene. Processes of the present disclosure can provide butyl rubbers made entirely of bio-based monomers – from highly pure isobutylene and optionally the isoprene comonomer. Additives may also be bio-based. [0157] The phrases, unless otherwise specified, "consists essentially of" and "consisting essentially of" do not exclude the presence of other steps, elements, or materials, whether or not, specifically mentioned in this specification, so long as such steps, elements, or materials, do not affect the basic and novel characteristics of the present disclosure, additionally, they do not exclude impurities and variances normally associated with the elements and materials used. [0158] For the sake of brevity, only certain ranges are explicitly disclosed herein. However, ranges from any lower limit may be combined with any upper limit to recite a range not explicitly recited, as well as, ranges from any lower limit may be combined with any other lower limit to recite a range not explicitly recited, in the same way, ranges from any upper limit may be combined with any other upper limit to recite a range not explicitly recited. Additionally, within a range includes every point or individual value between its end points even though not explicitly recited. Thus, every point or individual value may serve as its own lower or upper limit combined with any other point or individual value or any other lower or upper limit, to recite a range not explicitly recited. [0159] All documents described herein are incorporated by reference herein, including any priority documents and or testing procedures to the extent they are not inconsistent with this text. As is apparent from the foregoing general description and the specific embodiments, while forms of the present disclosure have been illustrated and described, various modifications can be made without departing from the spirit and scope of the present disclosure. Accordingly, it is not intended that the present disclosure be limited thereby. Likewise, the term “comprising” is considered synonymous with the term “including” for purposes of United States law. Likewise whenever a composition, an element or a group of elements is preceded with the transitional phrase “comprising,” it is understood that we also contemplate the same composition or group of elements with transitional phrases “consisting essentially of,” “consisting of,” “selected from the group of consisting of,” or “is” preceding the recitation of the composition, element, or elements and vice versa. [0160] While the present disclosure has been described with respect to a number of embodiments and examples, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments can be devised which do not depart from the scope and spirit of the present disclosure.

Claims

IN THE CLAIMS 1. A process comprising: dehydrating a bio-based isobutanol in an isobutanol dehydration unit to form a butenes composition; and providing the butenes composition to one or more of an acid extraction unit or a butyl ether formation unit.

2. The process of claim 1, further comprising providing a byproducts fraction from the isobutanol dehydration unit to the acid extraction unit or the butyl ether formation unit.

3. The process of claim 1, wherein the butenes composition is provided to the butyl ether formation unit and comprises introducing the butenes composition with methanol and a catalyst to form methyl tert-butyl ether.

4. The process of claim 3, further comprising providing the methyl tert-butyl ether to a butyl ether decomposition unit to form an isobutylene product that is 99 wt% or greater isobutylene.

5. The process of claim 1, wherein the butenes composition is provided to the acid extraction unit to form a tert-butanol product.

6. The process of claim 5, further comprising providing the tert-butanol product to a tert-butanol dehydration unit to form an isobutylene product that is 99 wt% or greater isobutylene.

7. The process of claim 6, further comprising: providing a portion of the bio-based isobutanol to the tert-butanol dehydration unit to form a second butenes composition; providing the second butenes composition to the acid extraction unit to form a second tert- butanol product; and providing the second tert-butanol product to the tert-butanol dehydration unit to form a second isobutylene product that is 99 wt% or greater isobutylene.

8. The process of claim 6, further comprising: providing a portion of the bio-based isobutanol to a catalytic cracking unit at cracking conditions to form a second butenes composition, wherein the cracking conditions comprise a temperature of about 450 ^oC to about 650 ^oC and a pressure of about 250 kPa to about 400 kPa; providing the second butenes composition to the acid extraction unit to form a second tert- butanol product; and providing the second tert-butanol product to the tert-butanol dehydration unit to form a second isobutylene product that is 99 wt% or greater isobutylene.

9. The process of claim 4 or 6, further comprising reacting at least a portion of the isobutylene product with formaldehyde to form an isoprene product.

10. The process of claim 7 or 8, further comprising reacting at least a portion of the second isobutylene product with formaldehyde to form an isoprene product.

11. The process of claim 4 or 6, further comprising polymerizing the isobutylene product and, optionally, a comonomer, to form an isobutylene-based polymer.

12. The process of claim 7 or 8, further comprising polymerizing the second isobutylene product and, optionally, a comonomer, to form an isobutylene-based polymer.

13. The process of claim 9, further comprising polymerizing a second portion of the isobutylene product and, optionally, a comonomer, to form an isobutylene-based polymer.

14. The process of claim 10, further comprising polymerizing a second portion of the second isobutylene product and, optionally, a comonomer, to form an isobutylene-based polymer.

15. The process of claim 3, wherein the catalyst comprises an acidic sulfonated macroporous polystyrene-divinyl benzene ion exchange resin.

16. The process of claim 15, wherein a molar ratio of methanol to isobutylene is about 0.9 to about 1.2.

17. A process comprising: providing a bio-based isobutanol to an alcohol dehydration unit to form a butenes composition; providing the butenes composition to an acid extraction unit to form a tert-butanol product; and providing the tert-butanol product to the alcohol dehydration unit to form an isobutylene product that is 99 wt% or greater isobutylene.

18. The process of 17, further comprising polymerizing the isobutylene product and, optionally, a comonomer, to form an isobutylene-based polymer.

19. A process comprising: providing a bio-based isobutanol to an alcohol dehydration unit to form a butenes composition; providing the butenes composition to a butyl ether formation unit to form a butyl ether product; and providing the butyl ether product to a butyl ether decomposition unit to form an isobutylene product that is 99 wt% or greater isobutylene.

20. The process of 19, further comprising polymerizing the isobutylene product and, optionally, a comonomer, to form an isobutylene-based polymer.

21. A process comprising: providing a bio-based isobutanol to a catalytic or steam cracking unit at cracking conditions to form a butenes composition, wherein the cracking conditions comprise a temperature of about 450 ^oC to about 650 ^oC and a pressure of about 250 kPa to about 400 kPa; providing the butenes composition to an acid extraction unit to form a tert-butanol product; and providing the tert-butanol product to an alcohol dehydration unit to form an isobutylene product that is 99 wt% or greater isobutylene.

22. The process of 21, further comprising polymerizing the isobutylene product and, optionally, a comonomer, to form an isobutylene-based polymer.

23. A process comprising: providing a bio-based isobutanol to a catalytic or steam cracking unit at cracking conditions to form a butenes composition, wherein the cracking conditions comprise a temperature of about 450 ^oC to about 650 ^oC and a pressure of about 250 kPa to about 400 kPa; providing the butenes composition to a butyl ether formation unit to form a butyl ether product; and providing the butyl ether product to a butyl ether decomposition unit to form an isobutylene product that is 99 wt% or greater isobutylene.

24. The process of 23, further comprising polymerizing the isobutylene product and, optionally, a comonomer, to form an isobutylene-based polymer.

25. The process of claim 24, further comprising performing a chain-of-custody mass balance process to attribute bio-based content to the isobutylene-based polymer.

26. A process comprising: providing a bio-based isobutanol to a catalytic or stream cracking unit that is connected through a series of process steps to a unit that produces 99 wt% or greater isobutylene, and performing a chain-of-custody mass balance process to attribute bio-based content to the isobutylene.

27. The process of claim 26, further comprising feeding one or more additional bio-based alcohols to the cracking unit.

28. The process of 26, further comprising polymerizing the isobutylene product and, optionally, a comonomer, to form an isobutylene-based polymer.

29. The process of claim 28, further comprising performing a chain-of-custody mass balance process to attribute bio-based content to the isobutylene-based polymer.