WO1990011267A1

WO1990011267A1 - Novel integrated separation method for di-isopropyl ether and methyl tertiary alkyl ether processes

Info

Publication number: WO1990011267A1
Application number: PCT/US1990/001479
Authority: WO
Inventors: Mohsen Nadimi Harandi; Hartley Owen
Original assignee: Mobil Oil AS
Current assignee: Mobil Oil AS
Priority date: 1989-03-23
Filing date: 1990-03-19
Publication date: 1990-10-04
Anticipated expiration: 1991-09-23
Also published as: EP0416095A1; AU5405190A; CA2027574A1; JPH03504731A

Abstract

The process for manufacturing tertiary alkyl ethers such as MTBE, TAME and isopropyl tertiary alkyl ether and that for manufacturing di-isopropyl ether (DIPE) are integrated into an overall process to produce high octane gasoline rich in these ethers. The integration is preferably achieved in a combined separation step where the effluents from both etherification processes are fed to a water wash tower for separation into an organic phase containing C3+ hydrocarbons and oxygenates including C4+ ethers and an aqueous phase which contains methanol and isopropanol. The aqueous phase is recycled to the DIPE etherification zone while the organic phase is debutanized to produce a bottom stream comprising high octane gasoline rich ethers and an overhead stream comprising C4- hydrocarbons. The water wash step allows large excess quantities of methanol to be used in the MTBE etherification step without recycle. The invention advantageously employs a common water washing step and common debutanizing step in the manufacture of tertiary alkyl ethers and DIPE.

Description

NOVEL INIEGRATED SEPARATION METHOD FOR DI-TSOPROPYL

ETHER AND METHYL TERTIARY AIKYL EIHER PROCESSES

This invention relates to an integrated process and means for the production of high octane gasoline rich in methyl tertiary alkyl ether and di-isopropyl ether. More particularly, the invention relates to a novel method for cxinbining the separation of the independent product streams from the

manufacture of di-iscpropyl ether and methyl tertiary alkyl ether in the course of the production of high octane gasoline

containing such ethers.

Driven by the need to eliminate lead based octane enhancers in gasoline, processes to produce high octane gasolines blended with lower aliphatic alkyl ethers as octane boosters and supplementary fuels have been vigorously developed in the petroleum refining arts. C₅-C₇ methyl alkyl ethers, especially methyl tertiary butyl ether (MTBE) and tertiary amyl methyl ether (TAME) have been found particularly useful for enhancing gasoline octane. Therefore, improveanents to the processes related to the production of these ethers are matters of high importance and substantial challenge to research workers in the petroleum refining arts.

It is well kncwn that isobutylene may be reacted with methanol over an acidic catalyst to provide methyl tertiary butyl ether (MTBE) and isoamylenes may be reacted with methanol over an acidic catalyst to produce tertiary amyl methyl ether (TAME). The reaction is a useful preparation for these valuable gasoline octane enhancers and is typical of the reaction of the addition of primary to the more reactive tertiary alkenes of the type R₂ C=CH₂ or R₂C=CHR under mild conditions to form the corresponding tertiary alkyl ethers of lower alkanol, particularly methanol, ethanol and isopropanol. The feedstock for the etherification reaction may be taken from a variety of refinery process streams such as the unsaturated gas plant of a fluidized bed catalytic cracking operation containing mixed light olefins, preferably rich in isobutylene. Light olefins such as propylene and iscmers of butene other than isobutylene in the feedstock are essentially unreactive toward primary alcohols under the mild, acid catalyzed etherification reaction conditions employed to produce lower alkyl tertiary butyl ether.

m these etherification processes, a major problem importance is the separation of methanol from the etherification reaction product due to the proclivity of methanol to form a very dilute azeotropic mixture with hydrocarbons and the strong solubility of methanol in both water and hydrocarbons. While it would be useful from an equilibrium standpoint to use large excesses of methanol in etherification, subsequent separation problems have limited that process improvement. Due largely to these factors, the cost associated with methanol separation and recycling in the etherificaticai reaction represents approximately 30% of the cost of the total etherification process.

lower molecular weight alcohols and ethers such as isopropyl alcohol (IPA) and diiscprcpyl ether (DUE) are in the gasoline boiling range and are known to have a high blending octane number. They, as well as MTBE and TAME, are useful octane enhancers. In addition, by-product propylene from which IPA and DUE can be made is usually available in a fuels refinery. The petrochemicals industry also produces mixtures of light olefin streams in the C₂ and C₇ molecular weight range and the

conversion of such streams or fractions thereof to alcohols and/or ethers can also provide products useful as solvents and blending stocks for gasoline.

The catalytic hydration of olefins to provide alcohols and ethers is a well-established art for the production of the IPA and DIPE and is of significant commsrcial importance.

Representative olefin hydration processes are disclosed in U. S. Patents Nos. 2,262,913; 2,477,380; 2,797,247; 3,798,097;

2,805,260; 2,830,090; 2,861,045; 2,891,999; 3,006,970; 3,198,752; 3,810,848; 3,989,762, among others.

Olefin hydration employing zeolite catalysts is also kncwn. As disclosed in U. S. Patent No. 4,214,107, lower olefins, in particular prcpylene, are catalytically hydrated over a crystalline aluminosilicate zeolite catalyst having a silica to alumina ratio of at least 12 and a Constraint Index of from 1 to 12, e.g., acidic ZSM-5 type zeolite, to provide the corresponding alcohol, essentially free of ether and hydrocarbon by-product.

The production of ether frcro secondary alcohols such as isopropanol and light olefins is kncwn. As disclosed in U. S. Patent No. 4,182,914, DIPE is produced from IPA and propylene in a series of operations employing a strongly acidic cation exchange resin as catalyst. Recently, processes for the hydration of olefins to provide alcohols and ethers using zeolite catalyst have been disclosed in U. S. patent applications Serial Nos. 139,570, 139,567, 139,565, 139,569, 139,543 arxi 139,566.

Adapting available refinery feedstock to simultaneously produce the above oxygenates as octane enhancers can involve two different etherification processes, i.e., iso-olefin

etherification to give methyl tertiary alkyl ethers and

propylene hydration and etherification to give DUE and IPA. Accordingly, a challenge is provided to explore these processes to discover hew they may be integrated in a manner more

beneficial to the production of high octane gasoline. It has been discovered that the processes to manufacture tertiary alkyl ethers such as MIBE and TAME and processes to maπufacture di-isopropyl ether DIEE can be integrated in an overall process to produce high octane gasoline rich in these ethers. The integration is achieved in a contained separation step where the effluents from both etherification zones are passed to a common water wash tcwer for separation of an organic phase containing C₃+ hydrocarbons and oxygenates including C₄+ ethers. The aqueous phase from the water wash tower which contains methanol and isopropanol is recycled to the DUE etherification zone while the organic phase is debutanized to produce high octane gasoline rich in ethers and an overhead ccmprising C₄-hydrocarbons. The water wash step allows large excess quantities of methanol to be used in the MTBE

etherification step without recycle. Accordingly, the invention advantageously employs a cannon water washing step and common debutanizing step in the manufacture of tertiary alkyl ethers and DUE. The common water washing zone utilizes the DUE

etherificaticai zone water feed for the water washing process.

Mare particularly, the present invention provides an integrated continuous process for the production of C₄+ ether rich gasoline, the process comprising the steps of: contacting a fresh mixture of excess methanol and C₄+ hydrocarbon feedstock rich in tertiary olefins with an acidic etherification catalyst in a first etherification zone under tertiary olefin

etherificaticai conditions whereby an etherification effluent stream containing methyl tertiary alkyl ethers, unreacted methanol and C₄+ hydrocarbons is produced. Fresh C₃ olefinic hydrocarbon feedstock and an aqueous fraction containing unreacted methanol and isoprcpanol is contacted in a second etherificaticai zone with acidic olefin hydration catalyst under olefins hydration and etherificaticai conditions whereby an effluent stream containing oxygenates comprising di-isopropyy ether, methyl isopropyl ether and isoprcpanol is produced. The first and second etherification zone effluent streams are passed to a common water washing zone and the streams are separated therein to provide an organic fraction containing C₃+

hydrocarbons and C₄+ ethers plus the aqueous fraction Containing unreacted methanol and isoprcpanol. Gasoline boiling range hydrocarbons rich in C₄+ ethers are recovered frcro the organic fraction.

The process further comprises separating the DIPE effluent stream prior to water washing and recycling a major portion of the unreacted C₃ olefinic hydrocarbon, water and isoprcpanol components thereof to the DUE etherification zone while passing the oxygenates components thereof to the washing zone.

Another embodiment of the present invention comprises an integrated continuous process for the production of C₅+ ether rich gasoline comprising the steps of: contacting a fresh mixture of excess lower alkanol, a first C₄+ hydrocarbon feedstream rich in tertiary olefins and a second feedstream ccnprising

di-isoprcpyl ether and unreacted lower alkanol with an acidic etherification catalyst in a first etherification zone under tertiary olefin etherification conditions whereby an

etherification effluent stream containing C₅₊ ethers and unreacted alkanol is produced; separating the effluent stream in a water wash tower in contact with water feedstream to provide an organic fraction containing C₄+ hydrocarbons and C₅+ ethers and an aqueous phase comprising water and unreacted lower alkanol; separating said aqueous phase by distillation in cxxnbination with a distillation feedstream ccnprising di-isopropyl ether whereby an overhead stream ccnprising the second feedstream and a bottom stream containing water is produced; introducing the bottom stream and C₃ olefinic hydrocarbons into a second etherification zone in contact with acidic olefin hydration catalyst under olefins hydration and etherification conditions whereby an effluent stream containing di-isoprcpyl ether comprising said distillate feedstream is produced.

In the drawings. Figure 1 is a general block flow schematic of the present process.

Figure 2 is a flew schematic of a preferred embodiment of the process of this invention.

Figure 3 is a flow schematic of an embodiment of the present invention without methanol feed to the DUE

etherification zone.

In the preferred embodiment of the instant invention the principal components of known processes are integrated in a manner providing a highly advantageous and surprising advancement in refinery technology leading to the production of high octane gasoline blending components. Known processes are combined in a unique configuration that provides enhancement of the performance of component processes as well as achieving surprising advantages for the integrated process. The processes integrated include etherification to produce lower alkyl tertiary alkyl ethers such as MTBE (methyl tertiary butyl ether) and TKME (tertiary amyl methyl ether) and C₃ olefins hydration and etherification to produce alcohols and ethers such as DUE, IPA and methyl isopropyl ether.

lower alkyl in the present invention refers to C₁-C₃ altyl derived from etherification using lower alkanol such as methanol, ethanol or isoprcpanol. Tertiary alkyl refers to C₄-C₅ tertiary alkyl groups derived from the etherification of tertiary olefins. The term oxygenates or oxygenate as used herein comprises singularly or in combination C₁-C₈ lower aliphatic, acyclic alcohols or alkanol and symmetrical or unsymmetrical C₂-C₉ ethers.

The process of the present invention is directed to maximizing the utilization of C₃+ refinery streams for the production of those gasoline range oxygenated species, or oxygenates, kncwn to exhibit high octane numbers which are useful for gasoline product blending. Table 1 lists those oxygenated species of particular interest as products of the present

In the preferred embodiments of this invention, methanol is reacted with C₄+ olefinic hydrocarbon feedstock such as FCC unsaturated gas plant containing olefins, particularly iso-olefins, to produce methyl tertiary butyl ether. In the reaction, methanol or lower alkanol is generally present in a stoichiometric excess amount between 1 and 100 percent,

preferably 3%, based upon isobutylene. The presence of a substantial excess of methanol is a feature of this invention which allows increased conversion of tertiary olefins. The separation of unreacted methanol is achieved conveniently through the unique contribution of this invention as described

hereinafter.

Methanol may be readily detained from coal by gasification to synthesis gas and conversion of the synthesis gas to methanol by well-established industrial processes. As an alternative, the methanol may be obtained from natural gas by other conventional processes, such as steam reforming or partial oxidation to make the intermediate syngas. Crude methanol from such processes usually contains a significant amount of water, usually in the range of 4 to 20 wt%. The etherification catalyst employed is preferably an ion

exchange resin in the hydrogen form; however, any suitable acidic catalyst may be employed. Varying degrees of success are obtained with acidic solid catalysts; such as, sulfonic acid resins, phosphoric acid modified kieselguhr, silica alumina and acid zeolites. Typical hydrocarbon feedstock materials for etherification reactions include olefinic streams, such as FOC light naphtha and butenes rich in iso-olefins. These aliphatic streams are produced in petroleum refineries by catalytic cracking of gas oil or the like.

The reaction of methanol with isobutylene and isoamylenes at moderate conditions with a resin catalyst is

kncwn technology, as provided by R. W. Reynolds, et al., The Oil and Gas Journal. June 16, 1975, and S. Pecci and T. Floris,

Hydrocarbon Processing, December 1977. An article entitled "MIBE and TAME - A Good Octane Boosting Ccmbo," by J.D. Chase, et al., The Oil and Gas Journal. April 9, 1979, pages 149-152, discusses the technology. A preferred catalyst is a bifuncticaial ion exchange resin which etherifies and iscmerizes the reactant streams. A typical acid catalyst is Amberlyst 15 sulfonic acid resin, a product of Rchm and Haas Corporation.

MTBE is kncwn to be a high octane ether. The article by J.D. Chase, et al.. Oil and Gas Journal, April 9, 1979, discusses the advantages one can achieve by using these materials to enhance gasoline octane. The octane blending number of MTBE when 10% is added to a base fuel (Rto = 91) is about 120. For a fuel with a lew motor rating (M+O = 83) octane, the blending value of MTBE at the 10% level is about 103. On the other hand, for an (R+O) of 95 octane fuel, the blending value of 10% MTBE is about 114. Processes for producing and recovering MTBE and other methyl tertiary alkyl ethers from iso-olefins are known to those skilled in the art, such as disclosed in U.S. Patents 4,544,776 (Osterburg, et al.) and 4,603,225 (Colaianne et al.). In the prior art various suitable extraction and distillation techniques are known for recovering ether and hydrocarbon streams from etherification effluent. Extraction and distillation techniques are used to recycle unreacted methanol. These techniques, as practiced in the prior art, are economically burdenscne upon the MEBE process involving, as they do, the extraction and

distillation of aqueous solutions. As a consequence of the cost associated with the aqueous extraction and distillation of aqueous solutions experienced in the process of separating unreacted methanol prior art processes tend to sharply limit the amount of excess methanol added to the MTBE etherification reaction. A compromise is struck between the cost of methanol separation and the favorable effect of excess methanol on the conversion of isoolefin to tertiary ethers. The method of the present obviates that compromise.

The olefins hydration and etherification process integrated in the present invention embodies the reaction of prcpylene with water catalyzed by strong acid to form

isopropanol. Reaction continues in the hydration zone to form di-isopropyl ether or, when a lcwer alcohol is present such as methanol, methyl isopropyl ether is also formed. The operating conditions of the olefin hydration process herein are not especially critical and include a temperature of from 100 to 450°C, preferably frcm 130 to 220°C and most preferably from 160 to 200°C, a pressure of frcm 790 to 24230 kPa (100 to 3500 psi), preferably from 3550 to 13890 kPa (500 to 2000 psi), a water to olefin mole ratio of frcm 0.1 to 30, preferably from 0.2 to 15 and most preferably from 0.3 to 5. The olefin hydration process of this invention can be carried out under supercritical dense phase, liquid phase, vapor phase or mixtures of these phases in batch or continuous manner using a stirred tank reactor or fixed bed flow reactor, e.g., trickle-bed, liquid-up-flow, liquid-down-flow, counter-current, co-current, etc. Reaction times of from 20 minutes to 20 hours when operating in batch and an IHSV of from 0.1 to 10 when cperating continuously are le. It is generally preferable to recover any unreacted olefin and recycle it to the reactor.

The catalyst employed in the olefin hydration and etherification operations is any lewis acid but preferably shape-selective acidic zeolite. 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.

Preferred catalysts include Zeolite Beta, Zeolite Y, ZSM-5, ZSM-35, and MCH-22. Both varieties of zeolites will possess a framework silica-to-alumina ratio of greater than about 7.

A convenient measure of the extent to which a zeolite provides controlled access to molecules of varying sizes to its internal strocture is the aforementioned Constraint Index of the zeolite. A zeolite which provides relatively restricted access to, and egress frcm, its internal structure is characterized by a relatively high value for the Constrain Index, i.e., above about 2. On the other hand, zeolites which provide relatively free access to the internal zeolitic structure have a relatively lew value for the Cutistraint Index, i.e., about 2 or less. The method by which Constraint Index is determined is described fully in U.S. Patent No. 4,016,218, to which reference is made for details of the method.

The large pore zeolites which are useful as catalysts in the process of this invention, i.e., 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-12, 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.

Zeolite Beta is described in U.S. Reissue Patent No.

28,341 (of original U.S. Patent No. 3,308,069), to which

reference is made for details of this catalyst.

Referring new to Figure 1, a general block flow schematic of the process of this invention is presented. The major units of the process include the DUE etherification section A

containing acidic catalyst, the MTBE etherification section B containing acidic catalyst, water wash tower C and debutanizer D. A hydrocarbon feedstock 110 containing propylene is passed to the DIPE etherification zone A while excess lower alcohol such as methanol is passed via conduit 115 to MTBE etherification zone B in conjunction with a hydrocarbon feedstock 120 rich in _C4+ isoolefins. Water for zone B olefins hydration is transferred via stream 125 to zone A as part of the aqueous phase from water wash tower C. The water transfer system frcm zone B to zone A includes water purge line 126.

The etherification reactions in zones A and B are carried out under known conditions as previously described herein. The effluents 130 and 135 from the etherification zones are passed to the common water wash tower C for extraction with water

introduced via 140. The aqueous phase from C containing unreacted methanol frcm B and isoprcpanol from A is passed to A as noted. The organic phase frcm C ccntaining DUE, C₄+ ethers and unreacted hydrocarbons from A and B is passed via stream 145 to debutanizer D for separation. An overhead stream 150 containing C₄- hydrocarbons plus a bottoms stream 155 ccnprising C₅+ gasoline containing ethers including DUE and MTBE exit from the debutanizer. The gasoline stream may also contain methyl iscpropyl ether, TAME and other ethers of C₄+ isoolefins.

Referring now to Figure 2 a flow schematic of a preferred esibodiment of the process of this invention is presented.

Methanol 210 and C₄+ hydrocarbon feedstock 215 are introduced into an etherification zone 220 containing a solid acidic catalyst such as Amberlyst 15. Methanol is in a stoichiometric excess amount compared to the isoolefin content of the C₄+ hydrocarbon feedstock but typically between 1 and 10% in excess. The etherification is carried out vender kncwn etherification conditions between a temperature of 60°C and 125 C and the effluent 225 comprising MTBE, TAME, unreacted methanol and unreacted C₄+ hydrocarbons is fed to a water wash tower 230, preferably after cooling.

A hydrocarbon feedstock 235 rich in prcpylene is passed to an olefins hydration and etherification zone 240 which preferably contains zeolite Beta catalyst. Hydration and etherificaticai is carried out under kncwn conditions in contact with water introduced as a ecupenent of the aqueous phase 245 containing methanol and isoprcpanol separated from

water wash tower 230. The effluent from the DUE etherification zone 240 is separated in a high pressure separator 250 and water and isoprcpanol components of the effluent are recycled 255 to the etherification reactor. After cooling, unreacted C₃ hydrocarbons are fed via 260 to a high pressure flash evaporator 265 and separated at a pressure preferably less than about 350 kBa lower than the etherification zone 240 pressure. A major portion of the unreacted C₃ hydrocarbcai component of the effluent stream is preferably re-compressed 275 and recycled 270 to the hydration and etherification zone 240. The bottom fraction 280 of the flash evaporator which contains ethers frcm 240,

isoprcpanol and seme C₃ hydrocarbon is cooled and passed to the water wash tower 230.

From the water wash tower 230 exit the previously noted aqueous phase 245 and an organic phase 290 which contains C₃+ hydrocarbons and ethers frcm both etherificaticai zones 220 and 240 ccnprising DIPE, MTBE and TAME. In the DUE etherification reactor excess methanol from the MTBE reactor is mostly converted to methyl iscpropyl ether. The organic phase is separated in debutanizer 295 to produce C₄-hydrocarbons 296 and high octane gasoline 297 rich in C₄+ ethers.

The process of the present inventicn uniquely uses only one debutanizer to stabilize DUE products and methyl tertiary alkyl ether products. Also, the process uniquely uses one water wash tower to absorb etherification excess methanol and DUE process iscpropyl alcohol byproduct into the DUE water feed.

As described hereinafter for another embodiment of the invention, it has been discovered that cycling unreacted lower alkanol to the DUE reactor can be avoided by carrying cut water washing of the effluent frcm tertiary olefins etherification immediately dewnstream of the etherificaticai zone and separating the aquecus phase by distillation in a common distillation tower for both the product of DUE etherification and unreacted lower alkanol. The aquecus distillate is transferred to the DUE etherification zone as reactant in that process. The ether rich gasoline product is collected by separating the organic phase from the water wash tcwer.

Referring new to Figure 3, the other embodiment of the instant invention is presented wherein no methanol from the MTBE etherification zone is sent to the DUE etherification zone. In this variation, the formation of methyl isopropyl ether in the DUE etherificaticai zone is avoided. Feedstream 310 containing lower alkanol such as methanol and C₄+ hydrocarbon is fed to MTBE etherification zone 320 in contact with acidic etherificaticai catalyst as described hereinbefore. The effluent stream 330 from the MTBE zone is passed to water wash column or separator 340 and separated in contact with water wash feedstream 350. This feedstream serves to provide both water for the physical separation of the components as required in the process and as the required reactant in the DUE etherification zone. The organic phase 360 is fed to debutanizer distillation fractiαnator 370 where an overhead stream 380 containing C₃ and C₄

hydrocarbons is separated. The bottom effluent stream 390 from the debutanizer comprises ether-rich gasoline. The aqueous phase 305 from water wash column 340 containing water and unreacted methanol from the etherification zone 320 is passed to

distillation separator 315. A bottom stream 325 containing water and isopropyl alcohol (IPA) is separated from separator 315 and transferred to DUE etherification zone 335 via conduits 336 and 337 and pump 338. C₃ hydrocarbon feedstream 345 is passed to etherification zone 335 in contact with acidic catalyst as described herein before. The effluent 355 from zone 335 is passed to separator 365 for separation of a bottom stream 339 containing water and isopropyl alcohol which is transferred to zone 335 by pump 341. The overhead stream 375 cxartaining water,

C₃, IPA and DUE is passed to distillation separator 385. An overhead stream 395 ccnprising C₃ hydrocarbons is separated and a bottom stream 396 ccnprising C₃ hydrocarbons, water, IPA and DUE is passed to distillation separator 315. From separator 315 an overhead stream 398 is separated containing C₃ hydrocarbons, DUE, IPA and unreacted methanol. Conduit 400 connected to conduit 325 can be used for blow-down. While the invention has been described by specific examples and embodiments, there is no intent to limit the inventive concept except as set forth in the following claims.

Claims

CLAIMS:

1. An integrated contimucus process for the production of C₄+ ether rich gasoline ccnprising the steps of:

(a) contacting a fresh mixture ccnprising excess C₁-C₈ lower alkanol and C₄+ hydrocarbon feedstock rich in tertiary olefins with an acidic etherificaticai catalyst in a first etherificaticai zone under tertiary olefin etherification conditions to produce a first etherificaticai effluent stream σcaϊtaining lcwer altyl tertiary alkyl ethers, unreacted lcwer alkanol and C₄+ hydrocarbons;

(b) contacting fresh C₃ olefinic hydrocarbon feedstock and an aquecus fraction αxitaiLning a lower alkanol and

isoprcpanol in a second etherificaticai zone with an acidic olefin hydration catalyst under olefins hydration and etherification conditions at a tamperature of 50° and 300°C to produce a second etherificaticai effluent stream containing isoprcpanol and oxygenates ccnprising di-isopropyl ether and lower alkyl iscpropyl ether;

(c) passing the first and second etherification effluent streams to a water washing zone and separating the streams to provide an organic fraction containing C₃+ hydrocarbons and C₄+ ethers and an aqueous fraction containing unreacted lcwer alkanol and iscpropanol; and

(d) recovering gasoline boiling range hydrocarbons rich in C₄+ ethers from the organic fraction.

2. The process of claim 1 further ccnprising separating the second etherification effluent stream into one stream ccnprising unreacted C₃ olefinic hydrocarbon, water and

iscpropanol, which stream is recycled to the second

etherification zone, and another stream ccnprising the

oxygenates, which stream is recycled to the washing zone.

3. The process of claim 2 wherein the C₃'s are separated by distillation at a pressure less than the pressure of the second etherification zone.

4. The process of claim 3 wherein the pressure is 350 kPa less than the second etherification zone.

5. The process of claim 1 wherein the water washing zone comprises a water washing tower.

6. The process of claim 1 further ccnprising passing the organic fraction from step (c) to a debutanizer to separate into a C₄- hydrocarbon overhead fraction and an ether rich gasoline bottom fraction.

7. The process of claim 1 wherein step (b) olefins hydration catalyst comprises acidic shape selective zeolite.

8. The process of claim 7 wherein the zeolite is selected frcm intermediate pore size or large pare size zeolites having a Constraint Index of 2 to 12 or zeolites possessing a Constraint Index of 2 or less.

9. The process of claim 7 wherein step (b) hydration catalyst is selected from zeolites ZSM-5, ZSM-11, ZSM-23, ZSM-35, ZSM-38, Beta, X, L, Y, USY, REY, Deal Y, Re Deal Y, ZSM-3, ZEM-4, ZSM-12, ZSM-20, ZSM-50, MCM-22 and sulfuric acid resins.

10. The process of claim 1 wherein the olefins hydration and etherification conditions conprise temperature between 110 to 200°C.

11. The process of claim 1 vherein the lower alkyl tertiary alkyl ethers conprise methyl tertiary butyl ether and inethyl tertiary amyl ether.

12. The process of claim 1 wherein the excess alkanol comprises a large stoichiometric excess of alkanol based en tertiary olefins in the C₄+ hydrocarbon feedstock.

13. The process according to claim 12 wherein the stoichiometric excess is between 1 and 100 wt%.

14. The process according to claim 13 wherein the stoichicπetric excess is 3 wt%.

15. The process of claim 1 wherein the tertiary olefins conprise iscbutylene and isoamylene.

16. The process of claim 1 wherein step (a) acidic etherification catalyst is selected from zeolites ZSM-5, ZSM-11, ZSM-23, ZSM-35, ZSM-38, Beta, X, L, Y, USY, REY, Deal Y, Re Deal Y, ZSM-3, ZSM-4, ZSM-12, ZSM-20, ZSM-50, MCM-22 and sulfuric acid resins.

17. The process of claim 1 wherein step (a) is conducted at a temperature between 60 and 125°C.

18. An integrated separator means for the separation of the effluent streams frcm di-iscprcpyl ether manufacturing zone and frcm methyl tertiary alkyl ether maπufacturing zone in the production of ether rich high octane gasoline, ccnprising in combination:

water wash means for separating water soluble components in an organic stream containing C₄+ ethers receivable connected to receive water and effluents frcm first and second reactor means;

first reactor means far containing methyl tertiary alkyl ether manufacturing zone operatively connected to the water wash means;

second reactor means for containing di-iscpropyl ether manufacturing zone operatively connected to the water wash means;

first conduit means, connected to the water wash means, for withddrawing aquecus phase therefrom; second conduit means, connected to the water wash means, for withdrawing organic phase therefrom.

19. The process of claim 1 wherein the lower alkanol is selected frcm methanol, ethanol and isoprcpanol.

20. The process of claim 1 wherein the C₅+ ethers comprise di-isopropyl ether and lcwer alkyl tertiary alkyl ethers.

21. The process of claim 20 wherein the lower alkyl tertiary alkyl ethers are selected frcm methyl tertiary butyl ether, methyl tertiary amyl ether, ethyl tertiary butyl ether and iscpropyl tertiary butyl ether.

22. The process of claim 1 wherein the step (a) lower alkanol comprises iscpropyl alcohol comprising the reaction product of the step (d) etherification zone.