US2375041A - Alkylation of aromatic hydrocarbons - Google Patents

Description

Patented May 1-, 1945 ALKYLATION OF AROMATIC HYDROCARBONS Louis S chmerling and Vladimir N. Ipatieil, Chicago, Ill., assignors to Universal Oil Products Company, Chicago, 111., a corporation of Dela- No Drawing. Application August 11, 1941, Serial N0. 406,408

13 Claims. (Cl. 260- 671) This invention relates to the treatment of arcmatic hydrocarbons to produce alkylated aromatic hydrocarbons. More specifically it is concerned with the production of mono-alkylated and poly-alkylated aromatic hydrocarbons in the presence of a catalyst. It is recognized that in generalthe catalytic alkylation of aromatic hydrocarbons has been known for some time. However, the present invention differentiates from the prior art on this subject in the-use of a particular catalytic material comprising as its active ingredient cupric orthophosphate or a material formed by calcinoing cupric orthophosphate at a temperature of from about 200 to about 400 C.

In one specific embodiment the present invention comprises a process for producing alkylated aromatic hydrocarbons which comprises subjecting an aromatic hydrocarbon and an olefinic hydrocarbon to contact under .alkylating conditions in the presence of a catalyst containing as its active ingredient a material formed by calcining cupric orthophosphate.

Aromatic hydrocarbons, such as benzene, toluene; other alkylated be'nzenes, naphthalene, alkylated naphthalenes, other poly-nuclear aromatics, etc., which are-alkylated by oleflnic hydrocarbons as hereinafter set forth, may be obtained by the distillation of coal, by the dehydrogenation of naphthenic hydrocarbons, by the dehydrogenation and cyclization of aliphatic hydrocarbons, alkylated aromatic hydrocarbons, and alkylated naphthenic hydrocarbons,. and by other means.

Olefinic hydrocarbons utilizable as alkylating agents in the present instance comprise monoolefins and poly-olefins. Olefins which are employed in'the present process are either normally gaseous or normally liquid and comprise ethylene and its higher homologs, both gaseous and liquid, the latter including various polymers of normally gaseous olefins, but these different olefinic hydrocarbons and those mentioned hereinafter are not necessarily equivalent in their action as alkylating agents. Cyclic olefins may also serve in alkylating aromatic hydrocarbons but generally under conditions of operation diiiernt from' those employed when alklating aromatic hydrocarbons bynon-cyclic olefins, and this reaction may involve intermediate formation of olefins from cycloparaflins in the presence of the catalyst. Other olefinic hydrocarbons which may be interacted with the above indicated aromatic hydrocarbons include conjugated diolefins such as butadiene and isoprene, also non-conjugated diolefins, and other poly-olefins.

Oleflnic hydrocarbons utilizable as alkylating agents are obtainable from any source and are present in products of thermal and catalytic cracking of oils, in those obtained by dehydrogenating paraflinic and oleflnic hydrocarbons or in the products resulting from dehydrating alcoa hols.

Alkylation of aromatic compounds may also be eiiected in the presence of catalysts hereinafter described by charging with the aromatic hydrocarbon a substance capable of producing oleflnic hydrocarbons under the operating conditions chosen for the reaction. Such olefin-producing substances include alcohols, ethers, esters, and alkyl halides which are capable of undergoing dehydration or splitting to olefinic hydrocarbons, containing at least 2 carbon atoms per molecule, which may be considered as present in the reaction mixture even though possibly only as transient intermediate compounds which react further with aromatic hydrocarbons to produce desired reaction products.

Catalysts suitable for'use in effecting the process of the present invention comprise cupric orthophosphate or a material formed by calcining hydrated cupric orthophosphate at a temperature generally within the range utilized in the alkylation reaction namely from about 200 I to about 400 C. The hydrated cupric orthophosphate, the corresponding anhydrous salt, or a copper phosphate with an intermediate degree of hydration is utilizable as alkylating catalyst either as such or composited with a carrier such as alumina, silica, silica-alumina composites, diatomaceous earth, crushed porcelain, pumice, firebrick, etc; The addition to the catalyst, before final drying thereof, of free phosphoric acid may increase the alkylating activity of the resulting composite catalyst.

A composite catalyst of the typ hereinabove described in finely powdered form is thoroughly mixed, then subjected to drying, pelleting, and heating operations, the latter carried out in a stream of air, nitrogen, or hydrocarbon gases, etc., to produce formed particles of catalyst suitable for use as packing material in a reactor employed for effecting alkylation of aromatic hydrocarbons by olefinic hydrocarbons. Also, the copper orthophosphate or material formed by calcining this salt may be similarly formed into partiary carbon atom as is present in isobutene, trimethyl ethylene, etc. The difierent alkylating catalysts which may be thus prepared and employed in the present process are not necessaril equivalent in their action. 7

Cupric phosphate contains no acidic hydrogen atoms but nevertheles it is an active alkylatin catalyst. Although the reactions of this metallic Y ular proportion of olefinic hydrocarbon to between about 400 C. under a pressure of from substantially atmospheric to approximately 100 atmospheres. Intimate contact of the reacting components with the catalyst is effected by passing the reaction mixture through a fixed bed of granular or pelleted catalyst or the reacting components may be mixed with finely divided catalyst and reacted in either a batch or continuous type of operation. Thehydrocarbons subjected to reaction are preferably in the proportion of 1 molecabout 2 and about molecular proportions of aromatic hydrocarbon in order to diminish polymerization-of olefinic hydrocarbons and to favor i5 salt are not understood completely, the alkylating activity of copper orthophosphate which contains water of crystallization may be due to partial hydrolysis under operating conditions to produce certain amounts of free phosphoric acid as illustrated by the following equation:

Cu: (P04) 2 ZCLKOH) 2+CuP20s-f-4H20 The products obtained by heating the trihydrate appeared to consist chiefly of a basic metaphosphate of copper having the same empirical formula as that of cupric pyrophosphate. However, the latter compound as well as the orthophosphate dissolve readily in ammonium hydroxide yielding the deep blue color characteristic of cupric-ammonium compounds, while the calcination product does not dissolve. Thus it is probable that the active ingredient of the alkylating catalyst is not trihydrated cupric phosphate but possibly a partially dehydrated or anhy drous copper phosphate or an acid copper pyrophosphate, the latter formed by reduction of part of the catalyst composite.

In effecting reaction between aromatic hydrocarbon and an alkylating agent, as an olefinic hydrocarbon, according to the process of the present invention, the exact method of procedure varies with the nature of the reacting constituents. A simple procedure, utilizable in the case of an aromatic hydrocarbon which is normally liquid. or if solid is readily soluble or easily dispersible in a substantially inert liquid, and a normally gaseous or liquid olefinic hydrocarbon, consists in contacting the aromatic and olefinic hydrocarbons with a catalyst containing copper orthophosphate or a material formed by calcining copper orthophosphate under the alkylating conditions which comprise a temperature of from about 200 to interaction of olefinic hydrocarbons with the aromatic hydrocarbon or mixture of aromatic hydrocarbons in the hydrocarbon fraction undergoing treatment. The addition of a hydrogen-containing gas to the alkylation mixture frequently has a beneficial effect upon the reaction.

Thus a hydrocarbon mixture comprising essentially normally liquid aromatic hydrocarbons and a fraction containing olefinic hydrocarbons are commingled and passed through a reactor containing a catalyst as herein described, or at least a portion of the aromatic hydrocarbon is charged to such a reactor while the fraction containing olefinic hydrocarbons, as such or preferably diluted by another portion of the aromatic hydrocarbon being treated, is introduced at various points between the inlet and the outlet of the reaction zone in such a way that the reaction mixture being contacted with the catalyst will at all times contain a relatively low proportion of the olefinic hydrocarbon and thus favor interaction of aromatic and olefinic hydrocarbons rather than polymerization of the latter.

While the method 01' passing the aromatic and olefinic hydrocarbons, either together or countercurrently, through a suitable reactor containing the granular catalyst is generally customary procedure, the interaction of these hydrocarbons may also be eflected in a closed vessel in which some of the reacting constituents are in liquid phase and in which the catalyst is preferably in finely divided form and is maintained in dispersion or suspension by some method of agitation. The choice of operating procedure is dependent upon the circumstances such as the temperature, pressure, and activity of catalyst found to be most effective for producing the desired reaction between particular aromatic and olefinic hydrocarbons.

Copper phosphate-containing catalysts as herein described are preferred because they permit continuous reaction of aromatic and olefinic hydrocarbons in the presence of a fixed bed of catalyst and thus make it possible to avoid mechanical problems as well as oxidation and corrosion difficulties encountered when this reaction is carried out in the presence of sulfuric acidwhich is sometimes used as an alkylating catalyst. Further, a catalyst of the described type also has the advantage over aluminum chloride utilized as catalyst for alkylating aromatic compounds with olefinichydrocarbons in that the copper phosphatecontaining catalyst forms substantially no addition compounds or complexes with aromatic and/or olefinic hydrocarbons as is characteristic of catalysts containing aluminum chloride.

Reactions between aromatic and olefinic hydrocarbons in the presence of the herein described catalysts are apparently of a relatively simple character, although they may be'accompanied by certain amounts of polymerization and decommeans.

position. While not understood completely, a typical alkylation of an aromatic hydrocarbon by an olefin apparently involves the addition of the aromatic hydrocarbon to a double bond of an olefinic hydrocarbon to produce a higherboiiing alkylated aromatic hydrocarbon which may in turn undergo further reaction-with one or more molecular proportions of olefinic'hydrocarbons to form dialkylated and more-highly alkylated aromatic hydrocarbons. In case the alkylating olefinic hydrocarbon is adiolefin or other poly-olefin containing'more than one double bond per molecule, the interaction with an aromatic hydrocarbon may involve not only the combination of aromatic and olefinic hydrocarbons but possibly the polymerization of a higher boiling unsaturated aromatic hydrocarbon resulting from the primary reaction. Thus benzene and 1,3-butadiene give, among other products, a substantial yield of phenyl butene which polymerizes to form dimers of phenyl butene. Within certain limits it is possible to produce mainly mono-alkylated aromatic hydrocarbons by proper adjustment of catalyst activity, ratio of the aromatic to the olefinic hydrocarbons charged, operating conditions such as temperature, pressure, and rate of feed of the reacting components, etc.

The reaction between an aromatic hydrocarbon and a hexene or other normally liquid olefln of higher molecular weight may involve not only addition of aromatic and oleilnic hydrocarbons but also a depolymerization or splitting of the olefinic hydrocarbon into olefinic fragments of lower molecular weights which react with the aromatic hydrocarbons to produce alirylated aromatic hydrqcarbons. Thus benzene and di-isobutene or tri-isobutene react and yield tertiary butyl bencate'd ranges because of the fact that cupric phospate undergoes hydrogenation to form free copper and phosphoric acid. Thus when parts by weight of cupric orthophosphate trihydrate was which corresponded quite closely-to the theoretical yield of 22.6 parts byweight.

The following examples are given to illustrate the character of results obtainable by the use of the present process, although the examples given are not introduced with the intention of unduly restricting the generally broad scope of the invention.

Example I In a batch type operation 80 parts by weight of benzene, 20 parts by weight of propene, and 10 parts by weight of cupric phosphate trihydrate were placed in an autoclave, nitrogen was added thereto to 50 atmosphere initialpressure and the reaction mixture was heated 4 hours at 300 C. 90 parts by weight of liquid products were thus obtained which contained 32 parts by weight of mono-isopropyl benzene, and 7 parts by weight of a mixture of di-isopropyl benzene and morezeneand poly-tertiary butyl benzenes, while nonene and benzene yield both butyl and amyl benzenes as well as other products by so-called depoly-alkylation.

In general, the products formed by interaction of an olefinic hydrocarbon with a molal excess of an aromatic hydrocarbon are separated from the unreacted aromatic hydrocarbon by suitable means as by distillation, and the unreacted portion of the aromatic hydrocarbon originally charged and generally the poly-alkylated hydrocarbons formed are returned to the process and mixed with'additional quantities of the olefinic and aromatic hydrocarbons being charged to contact with the catalyst. This recycling of polyalkylated aromatic hydrocarbons'sometimes aids inthe production of mainly mono-alkylated aromatic hydrocarbons and depresses the formation of more-highly alkylated derivatives. The total alkylated product thus freed from the excess of the originally charged aromatic hydrocarbon is separated into desiredfractions by distillation at ordinary or reduced pressure or by other suitable While the process'of this invention'is particularly applicable to the production of alkylated aromatic hydrocarbons from aromatic and olefinic hydrocarbons, it may be utilized also in alkylating other aromatic compounds as in converting phenols and olefinic hydrocarbons into alkylated phenols using a catalyst containing copper orthophosphate or a material formed by calcining copper orthophosphate and generally operating within the range of temperature and pressure hereinabove set forth.

The presence in the reaction mixture of large amounts of hydrogen is generally not desirable highly propylated benzenes. Upon the basis of the propene charged, the yield of mono isopropyl benzene wa 56% of the theoretical.

Example II 50 parts by weight of cupric orthophosphate trihydrate was heated in an autoclave for 4 hours at 300 C. under 50'atmospheres initial nitrogen pressure and thereby converted into 43.5 parts by weight of bluish green powder.. This weight change corresponded to a'loss of 3 molecules of water per molecule .of copper phosphate trihydrate so treated. The bluish green powder so formed by heating the hydrated cupric phosphate was probably a basic phosphate and not just cupric pyrophosphate since the powder obtained reacted only very slowly with ammonium hydroxide while cupric pyrophosphate dissolves immediately in ammonia yielding the familiar type of blue solution containing copper-ammonium compounds.

Propylation ofbenzene parts by weight) by propene (20 parts by weight) in the presence of 10 parts by weight of the described bluish green powder was made by heating this mixture at 350 C. for 4 hours in the presence of nitrogen under an initial pressure of 50 atmospheres. The reaction mixture so formed contained 39 parts by weight of mono-isopropyl benzene and 10 parts by weight of more-highly propylated benzenes.

Another run made under the-same conditions but in the presence of 5 parts by weight of the calcined cupric phosphate and 4 parts by weight of'water yielded 38 parts by weight of mono isopropyl benzene and '7 parts by weight of morehighly proplyated benzenes.

reactor through which benzene and ethylene were particularly when operating under a relatively high temperature and pressure within the indipassed continuously. In each or three runs 70 parts by weight of benzene (80 volumes) and 14 parts by weight of ethylene were passed per hour through 40 volumes of catalyst under a pressure of 600 pounds per square inch and at the temperatures shown in the following table:

Table-Ethylation of benzene Ethyl benzenes, parts by Time, hours Catalyst weight per hour Run N 0. since begintempers ning of run ture, C Mono- Di- Residue Run #1 showed that little if any alkylation occurred at a temperature below 350 C. and that substantially complete absorption of the ethylene did not occur until the temperature was about 400 C. In run #2 17 hours at about 385 C. the catalyst decreased in activity as the run prograssed and the yield of ethyl benzene dropped about 35%. Run #3 showed that it wasbeneficial to initially use a relatively high catalyst temperature and to decrease this temperature as the run progressed. In this run in which the catalyst temperature was kept at about 385 C. during the first 3 hours, then'lowered to about 320 C. during the next 5 hours and kept at that temperature for 9 hours, the catalyst showed an activity at 320 C. equal to that obtained at 385 C. with fresh-catalyst. There was no drop in activity during a period of 9 hours at about 320 C., and when the catalyst temperature was then lowered to 262 C. a substantial yield of ethyl benzene was still obtained which was higher than that obtained at 363 C. in run #1.

From the results of these runs it appears that 'thecatalyst formed from copper phosphate requires a preliminary activation which is accomplished by use of a high initial temperature followed by a period of processing at a lower temperature at which there is less formation of carbon upon the catalyst than when a higher catalyst temperature is necessary during the entire run.

The character of the invention andthe type of results obtainable by its use in practice will be evident from the preceding specification and example given, although they are not to be considered as imposing undue limitations upon its generally broad scope.

We claim as our invention:

1. A process for producing alkylated aromatic hydrocarbons which comprises subjecting an aro-' matic hydrocarbon and an oleflnic hydrocarbon to contact under alkylating conditions in the presence of a catalyst containing as its active ingredient a material formed by calcining cupric orthophosphate.

2. A process for producingv alkylated aromatic hydrocarbons which comprises subjecting an aromatic hydrocarbon and an oleflnic hydrocarbon to contactat a temperature of from about-200 to about 400 C. under a pressure 01' from substantially atmospheric to approximately 100 atmospheres in the presence of a catalyst containing as its active ingredient a material formed by calcining cupric orthophosphate.

4. A process for producing alkylated aromatic hydrocarbons which comprises subjecting from about 2 to about 20 molecular proportions of an aromatic hydrocarbon and 1 molecular proportion of an oleflnic hydrocarbon to contact at a temperature or from about 200 to about 400 C. under a pressure oi. from substantially atmospheric to approximately 100 atmospheres in the presence of a catalyst containing as its active ingredient a material formed by calcining cupric orthophosphate.

5. A process for producing alkylated aromatic hydrocarbons which comprises subjecting an aromatic hydrocarbon and a normally gaseous olefinic hydrocarbon to contact at a temperature of from about 200 to about 400 C. under a pressure of from substantially atmospheric to approximately 100 atmospheres in the presence of a catalyst containing as'its active ingredient a material formed by calcining cupric orthophosphate.

' 6. A iprocess for producing alkylated aromatic hydrocarbons which comprises subjecting an aromatic hydrocarbon and a normally liquid olefinic hydrocarbon to contact at a temperature of from about 200 to about 400 C. under a pressure of from substantially atmospheric to approximately 100 atmospheres in the presence of a catalyst containing as its active ingredient a material formed by calcining cupric orthophos- 7: phate.

7. A process for producing alkylated benzenes which comprises subjecting from about 2 to about 20 molecular proportions oi benzene and 1 molecular proportion 01' an olefinic hydrocarbon to contact at a. temperature of from about 200 to about 400 C. under a pressure of from substantially atmospheric to approximately 100 atmospheres in the presence of a catalyst containing as its active ingredient a material formed by calcining cupric orthophosphate.

8. A process for producing alkylated benzenes which comprises subjecting from about 2 to about 20 molecular proportions of benzene and 1 molecular proportion 01' a normally gaseous oleflnic hydrocarbon to contact at a temperature of from about 200 to about 400 C. under a pressure of from substantially atmospheric to approximately 100 atmospheres in the presence of a catalyst containing as its active ingredient a ma- =terial formed by calcining cupric orthophosphate.

9. A process for producing alkylated benzenes which comprises subjecting from about 2 to about 20 molecular proportions of benzene and l molecular proportion of a. normally liquid olefinic hydrocarbon to contact at a temperature of from about 200 to about 400 C. under a pressure 01' from substantially atmospheric to approximately atmospheres in the presence of a catalyst containing as its active ingredient a material formed by calcining cupric orthophosphate.

10. A process for producing propylated benzenes which comprises subjecting from about! to about 20 molecular proportions of benzene and l-molecular proportion of prop'ene tocontact at a temperature of from about 200 to about 400 C. under a pressure of from substantially atmospheric to approximately 100 atmospheres in the presence of a catalyst containing as its active ingredient a material formed by calcining cupric orthophosphate. 11. A process for producing ethylated benzenes which comprises subjecting from about 2 to about 20 molecular proportions of benzene and 1 molecular proportion of ethylene to contact at a. temperature of from about 200 to about 400 C;

under a pressure" of from substantially atmospheric to approximately 100 atmospheres in the presence of a catalyst containing as its active ingredient a material formed by calcinins hydrated cupric orthophosphate. r

' 12. An alkylation process which comprises reacting an aromatic hydrocarbon with an olefin in the presence of cupric orthophosphate.

- 13. An alkylation process which comprises reactingan aromatic hydrocarbon with an olefin in the presence of a catalyst resulting from the calcinati'on of hydrated cupric orthophosphate.

LOUIS vmnmm min-1mm.