CA1157889A

CA1157889A - Ethyltoluene isomer mixtures

Info

Publication number: CA1157889A
Application number: CA000304223A
Authority: CA
Inventors: Lewis B. Young; Warren W. Kaeding
Original assignee: Mobil Oil Corp
Current assignee: ExxonMobil Oil Corp
Priority date: 1977-05-27
Filing date: 1978-05-26
Publication date: 1983-11-29
Also published as: IT1096347B; FR2391979B1; FR2391979A1; CS213344B2; AU523302B2; DE2821520A1; NL7805687A; DE2821520C2; DD136958A5; RO81394B; IT7823884A0; PL115231B1; JPS53147032A; BR7803383A; AU3653578A; GB1592129A; MX147739A; RO81394A; IN147121B; PL207109A1

Abstract

ABSTRACT OF THE DISCLOSURE
An ethyltoluene isomer mixture consisting essentially of from about 90 to about 99 weight percent of para-ethyltoluene, about 1 to about 10 weight percent of meta-ethyltoluene and 0 to about 0.1 weight percent of ortho-ethyltoluene, This isomer mixture is a valuable intermediate for the preparation of a vinyltoluene isomer mixture which in turn may be polymerized to polymers having unusual and advantageous proper-ties.

Description

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~9475 ~lis invention relate~ to ml~tures of tsomers of ~thyl-toluene.
Ethyltoluene is a valuable chemical. It may be dehydro-genated to produce the corresponding vinyl toluene. It has heretofore been recognized that the presence of substantlal quantities of the ortho i~omer is highly undesirable in ~he char~e undergoing dehydro-genation since it tends to lead to rin~ closure with formation of indenes and indanes which adversely affect the properties of polymers produced from the resultant vinyl toluene. Al~o, the indenes and indanes are difficult to separate from the desired vinyl toluene~ It has there~ore been necessary in the past to remove the ortho lsomer from the thyltoluene charge stocks b,y e~pensive distillatlon techniques prior to dehydrogenation.
It is evident~ therefore, that the ~vailability of ethyltoluene in which the ortho isomer i3 initially absent or present only in trace amount ~ould eliminate the necessity for the removal o~ thi~ lsomer. Such products have, however, ~ot heretofore been aYailable~ None of the known processes for producing ethyltoluene has been capable of producing a material with a minimal coutent of the or~ho isomer~
In the known mixtures of ethyltoluene isomers, the ~ara isomer has generally been present in an amount lesq than about 40 percent by weight; the meta isomer has generally been presert in ma~or proportion, together with ~maller amounts of the ortho isomer~ ~or example~ U~S~ Patent

2,763,702 of Amos et al describes a mixture of ethyltoluene isomers resulting from ethylation of toluene with ethylene in the presence of a Friedel-Crafts catalyst, such as alum~nu~ cllloride, contai~i~g isomeric mono-ethyl~oluenes in relativ~ proportions of from 8 to 30 percent of t~e ortho isomer, 40 to 65 perceIlt of the meta i50me~ and from 20 to 40 percent of the para isomer~
U.S. Patent 2,778,862 of Gorham et al also describes ethylation of toluene in the presence of an ... .. .. , ., .. ~ . . . . .. . .. .

~ ~..3'~r~5~3 aluminum chlorLde catal~st to yield an isomeric mixture in which the meta isomer predominates, the para isomer is present to a lesser degree and the ortho isomer is present in still smaller amount. A typical isomer mixture disclosed contains 10 to 20 weight percent of ortho-ethyltoluene, 25 to 30 weight percent of para ethyltoluene and 55 to 60 weight percent of meta-ethyl-toluene. U.S. Patent No. 2,920,119 (Egbert et al) refers to a conventional ethyltoluene isomer mixture obtained by ethylation of toluene in the presence of a Friedel-Crafts catalyst. This mixture has a meta isomer content of 72 percent, a para isomer content of 20 percent and an ortho isomer content of 8 percent.
In accordance with the process of this patent, the proportion of the para isomer is increased relative to the other isomers possibly by a combination of alkylation, disproportionation and isomerization steps to yield a resulting ethyltoluene isomer mixture which may contain about 20 percent of the ortho isomer, 50 percent of the meta isomer and 30 percent of the para isomer.
U.S. Patent Mo. 3,720,725 ~Olechowski3 dislcoses a reaction product mixture containing about 45 percent of ortho-ethyltoluene, about 38 percent para-ethyltoluene and about 3 percent of meta-ethyltoluene. This reaction mixture is obtained by alkylating an aromatic hydrocarbon using a catalyst composition comprising a molybdenum halide, an alkylaluminum dihalide and a proton donor.
~e have now devised a process for producing mixtures of the ethyltoluene isomers in which the content of the ortho isomer is minimal. According to the present invention the ethyltoluene isomer mixtures comprise from 90 to 99 weight per-cent of para-ethyltoluene, 1 to 10 weight percent of meta-ethyltoluene and are substnatially devoid, i.e., contain less than 0.1 weight percent, of ortho-ethyltoluene. The mixture is virtually free of the undesirable ortho-isomer. This is a sub-stantial advantage because there is no longer any need to carry out the expensive ~istillation, extraction or crystallization tech-niques which have previously been necessary to obtain ethyl toluene free of the ortho isomer.
The ethyltoluene isomer mixture of the invention is obtained by ethylating toluene with an ethylating agent in the presence of a catalyst having a controlled hexane cracking acti-vity, a minimum difusion time for ortho-xylene and a minimum xylene sorption capacity, as will be described more fully below.
The present invention, thus, resides in an ethyltoluene isomer mixture produced by ethylation of toluene and comprising at least 90 weight percent of para-ethyltoluene, 1 to 10 weight percent of meta-ethyltoluene and 0 to 0.1 weight per-cent of ortho-ethyltoluene, the ethylation conditions being such that said isomers are present in the aforementioned proportions in the direct reaction product of the ethylation, said isomer mixture being directly usable for preparing vinyltoluene without further purification.
In the product mixutre, the content of the para-isomer will generally be above 95%, preferably 97 to 99 weight percent with a meta-isomer content of less than 5 percent, preferably 1 to 3 percent. The ortho isomer is preferably present in an amount less than 0.05 percent. The para-isomer is often present in amounts from 98 to 99 percent with the meta-isomer present in amounts of 1 to 2 percent by weight.
The ethyltoluene can be readily dehydrogenated to form vinyl toluene ImethYl-ethenyl-benzene) mixtures with a corres-pondingly high ratio of the para isomer and minimal content of the ortho isomer. The dehydrogenation conditions will be the same as those previously used for the proudction of vinyl toluene from ethyl benzene by catalytic dehydrogenation. The resultant unsaturated materials are useful for conversion to high molecular weight polymers.

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The toluene is ethylated with an ethyla-tiny agent in the presence of a zeollte catalyst. The ethylating agen-t is generally ethylene or a gseous mixture high in this reactant.
Other suitable ethylating agents include ethyl alcohol and ethyl halides, e.g. ethyl chloride, dieth~l ether, diethyl sulfide and ethylmercaptan.
The reactants are brought into contact, under conversion conditions, with a bed comprising paxticle-form catalyst containing a crystalline aluminosilicate having: (1) an activity, in terms of alpha value, of between about 2 and about 5000, (2) a xylene sorp-tion capacity greater than 1 gram/100 grams of zeolite and ~3) an ortho-xylene sorption time for 30 percent capacity of greater than 10 minutes. The xylene sorption capacity and sorption time are measured at 120C. and a xylene pressure of 4.5 + 0O8 mm. of mercury.
The ethylation of the toluene is effectively accomplihsed at a temperature between about 250 and about 600C. at a pressure of between from 0.1 to 100 atmospheres utilizing a feed weight hourly space velocity (W~SV) between about 0.1 and about 100.
The latter WHSV is based on the wei~ht of catalyst composition, i.e. total weight of active catalyst and binder therefor. The molar feed ratio of toluene to ethylating agent is generally between 1 and 10.
The process is described in our Canadian Patent ~lo.
1,084,532, granted August 26, 1980, said patent being entitled "Selective Production of p-Dialkyl ~enzenes". As mentioned in that patent~ the zeolites which exhiblt a high selectivity for the production of the para-isomer require a very long time, up to and exceeding a thousand minutes, to sorb o-xylene in an amount of 30% of total xylene sorption capacity. ~or those materials lt is more convenient to determine the sorption time for a lower extent of sorption, such as 5%, 10%, or 20% of capacity, and to estimate the 30~O sorption time by applying a ~ 7 multiplica-tion factor as describecl irl said Canadian Pa-tent No.
1,08~,532.
The zeolite catalys-t used in the e-thylation step will be as clescribecl in Canadian Patent ~o. 1,Q8~,532, that is, a zeolite which freely sorbs normal hexane and has a pore dimension greater that 5 Anstroms and a constraint index in the approximate range of 1 to 12. Suitable zeolites include ZSM~5, Zs~ ZSM-12, ZSM-35, ZSM-38 and other similar materials, as disclosed in said Canadian Patent ~o. 1,084,532. The zeolites may be activated e.g. by heating in an inert atmosphere, followed by base exchanye and then calcination in air. The zeolites preEerably have a crystal framework density in the dry hydrogen form not substantially below 1.6 g./cc. Thus, the most preferred zeolites have a con-s-traint index of 1 to 12, a SiO2:A12O3 ratio of at least 12 and a dried crystal density of at leat 1.6 g./cc. The original alkali metal of the zeolite may be replaced by ion exchange with other ions of Groups IB to VIII of the Periodic Table. In addition, the zeolite may be incorporated in a matrix or composited with a porous matrix material such as alumina, silica-alumina, silica-magnesia, silica-zirconia, silica-thoria, silica-berylia, silica-titania as well as ternary compositions, such as silica-alumina-thoria, silica-alumina-zirconia, silica-alumina-magnesia and sllica-magnesia-zirconia. The matrix may be in the for~ of a cogel. The relative proportions of zeolite component and inorganic oxide gel matrix may vary widely with the zeolite content ranging from between about 1 to about 99 percent by weight and more usually in the range of about 5 to about 80 percent by weight of the composite.
The crystalline aluminosilicate zeolites employed are modified prior to use by combining therewith a small amount, generally in the range of 0.5 to ~0 weight percent, preferably of a difficulty reducible oxide, such as the oxides of phosphor-OU8, boron, magnesium or combinations thereof and also oxides of 4 ~i'J~.~

~ntimony. ~lodlfication of the zeolite with the desired oxi~e or oxides can readily be ef~ected by contacting the zeolite wlth a solution of an appropriate compound of the element to be introduced, followed by drying and calcining to conver-t the compound to its oxide form.
Suitable phosphorous oxides for this purpose are disclosed in Canadian Patent Mo. 1,084,532, -together with tech-niques for carrying out the reactlon between the zeolite and the phosphorous compound. The amount of phosphorous should, for the purposes of producing the present mixtures, be at least 0.5 percen-t by weight, preferably at least 2 percen-t when the zeolite i9 com bined with a binder. The amount o~ phosphorous oxide added to the zeolite is preferably from 0.7 to 15 percent.
Another suitable modifying oxide is magnesium oxide.
Suitable magnesium-containing materials and treatment procedures are disclosed in Canadian Patent ~lo. 1,084,532. The amounts of magnesium will be the same as those described in said Canadian Patent ~Jo. 1,084,532. P~epresentative boron containing compounds include boric acid, trimethylborate, boron hydride, boron oxide, boron sulfide, butylboron dimethyoxide, butylboronic acid, dimethyl-boric anhydride, hexamethylborazine, phenylboric acid, triethyl-borane, tetramethylammonium borohydride, triphenyl boron and allylborate.
Reaction of the zeolite with the boron compound is effected by contacting the zeolite with such compound. ~Jhere the treating boron compound is a liquid, it can be in solution in a solvent at the time contact with the zeolite is effected. ~ny solvent relatively inert with respect to the treating compound and the zeolite may be employed. Suitable solvents include water and aliphatic, aromatic or alcoholic liquids. ~Ihere the boron-containing compound is, for example, trimethylborate, a hydro-carbon solvent such as n-octane may be employed. The boron-~ 5~

containin~ compound may he used without a solvent, i.e., may be used as a neat liquid. Where the boron-con-taining comp~und ls in the gaseous phase, such as where gaseous diborane is employed, the trea-ting compound can be used by itself or can be used in admixture with a gaseous diluent inert to the boron--6a-containlng compound and the zeolite such ag llitrogen or helium or wlth an organic solvent, such as octane.
Prior to reacting the ~eolite with the boron-containing compound7 ~he zeolite may be dried. Drying can be effected in the presence of air. Elevated temperatures may be employed. However~ the temperature should not be s~ch that the crystal structure of the zeolite is destroyed.
~eat~ng of the boron-containlng catalyst sub~equent to preparatlon and prior to use i8 al~o pre~erred. The heating can be lQ carried out in the presence of oxygen, for example, air. Heating can beat a temperature of about 150C. but higher temperature~, up ~o about 500C
are preferred. Heating i9 generally carried out for 3-5 hours but may be extended to 24 hours or longer. While heating temperatures abo~e about 500C. csn be employed, they are not necessary. At temperatures of about 1000C., the crystal structure of the zeolite tends to deteriorate.
The amount of boron incorporated with the ~eolite should be at least 0.2 percent by weight. When the zeolite is combined with a binder, e.g~ 35 wt. percent of alumina, the amount of boron in the zeol~te is preferably a~ least about 1 percent by weight. The amoun~ of boron can be as high as about 20 percent by weight or more depending on the amo~mt and type of binder present. The amount of boron added to the zeolite is preferably from 1.5 to 10 percent by weight. Without being limited by any theoretical considerations, it is believed that boron is actually present in the zeolite in an oxidized state, such as B203.
Antimony oxide may also be employed as a modlfying component~
The antimony oxide is present as Sb203 alone or in ad~ixt~re ~ith other antimony oxides with or without metallic antlmony or other antimony com-pounds being present. In all instances~ regardless of the part:Lcular state of oxidation o the antimony, its content wlth respect to the zeolite ls computed as if it were present a3 Sb2O3. Generall77 the amount o~ Sb203 in the composite catalyst wiLl be from 6 to 40, preferably from lO to 35 ~elght percent. An~imony deriva~-lves which ma~
be used include: the hydrides SbH3 the halides MX3, MX5(M ~ Sb, X ~ F, Cl, Br, I); organic alkyl and aryl Y~ibines and their o~ide~ R3Sb~ R5Sb, RXSb~O ~R-alkyl or aryl); halogen derlvatives RSbX~, R2SbX, RSbX4 9 R2SbX3, R3SbX2, R4SbX; the acids H3SbO3, HSbO29 HSb(OH)6; organic acids ~uch as RSbO~OH)2, R2SbO OH~ all with R and X defined as above noted~
0 A190 included are organic ethers such as R2SbOSbR2; es~er~ and alcoholates such as Sb(OOCCH3)3, Sb(OC4Hg)3, Sb(OC2H5)3, Sb(OCH3)3; and antimonyl ~alts as (SbO)SO~, (SbO)NO3, ~(SbO)C4H4O6, ~aSbO2 3H2O.
In some instances, lt may be desirable to modify the crystalllne slumino3ilicate zeolite by combining two or more of the specified o~ides with it. Thus, for example, the zeolite may be modified by prior combination with of oxides of phosphorus and boron, oxides of phosphorus and magnesium or oxides of magnesium and boron. The oxides may be deposited on the zeolite either sequentially or from a solution containing suitable compounds of the elements, the oxide~ of w~ich are to be combined with the zeolite. The amounts of oxides present in such instance are in the same range as for the individual oxides, with the overall added oxide content being from 0.5 to 40 weight percent.
Still another modifying treatment entails steaming of the zeolite by co~tact with an at sphere co~aining from 5 to 100 percent steam at a temperature of from 250 to 1000C. for a period of between 0.25 and 100 hours and under pressures ranging from sub~atmospheric to several hundred atmospheres to reduce the alpha value to less than 500 and preferably less than approximately 20 but greater than ~ero.

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Another mocli~yincJ tre.ltment invo]~efi precoking of the ca-talyst to depos:it a coating of ~rom 2 to ~/5, preferably 15 to 75, weig}lt percent of coke on the cata]yst. Precokiny can be accom-plished by contacting the ca-talsyt with a hydrocarbon charye, e.g.
toluene, under high severity conditions or alternati~ely at a reduced hydrogen to hyclrocarbon concentration, i.e. 0 to l mole ratio of hydrogen to hydrocarbon for a sufficient-to ti~e deposit the desired amount of coke.
A combination of steaming and precoking of the catalyst may also be employed to suitably modify the crystalline alumino-silicate zeolite catalyst.
The conversion process described herein may be carried out as a batch type, semi-continuous or continuous operation utilizing a fixed or moving bed catalyst system as described in Canadian Patent No. 1,084,532.
To il]ustrate the improvement provided by the present invention, the following Examples are provided. Example l illus-trates the use of a known type of catalyst, aluminum chloride (a Friedel-Crafts catalyst). Only a low yield of the desired para-isomer is obtained. Example 2 illustrates the use of a zeolitecatalyst having an activity, alpha, of 2 to 5000, a xylene absorp-tion greater than lg/100 g. of zeolite and a xylene sorption time (30% capacity) greater than 10 minutes (sorption at 120C, xylene pressure 4.5 + 0.8 mm.Hg). The use of this catalyst produces a product which contains a high proportion of the desired para-isomer. ~xample 3 shows that products consisting almost exclu-sively of the para isomer can be obtained by appropriate choice of reaction conditions. Reference may also be made to the afore-mentioned Canadian Patent No. 1,084,532 for further examples of the catalysts which may be used and of suitable reaction conditions.

~xample 1 To 100 ml. of toluene was added 1 gram of alumlnum chloride and ethylene at a rate of 40 cc/minute at a te~perature of 80C. After 2 hours, the compositlon was that s~own in Table 1 below:

Component Wei~ght Percent Benzene 0.20 Toluene 71,90 Ethylbenzene 0.17 Xylene Para 0.15 Meta 0.06 Ortho 0.04 Ethyl Toluene Para 6.43 Meta 14.37 Ortho 3.24 Higher 1~45 _ Other 1.99 The para/meta/ortho ethyltoluene ratio was 27/60/13.

Example 2 Catalyst preparation A 5~3 gram sample of the hydrogen form of ZSM-5 having a crystallite size of about 2 microns was steamed at 515C~ for a period of 2 hours a~d a feed rate of 8.8 cc of liquld ~ater per hour. The temperature was then raised to 640C. Toluene was then fed at a rate of 180 ml per hour for a period of 4 hours and 15 minu~es. The temperature ~as then reduced to 550C., the catalyst flushed with nitrogen and ~hen cooled to yield a coke-containing product~
Toluene ethylatio_ Toluene was alkylated with ethylene in the presence of the above catalyst. The conditions of reaction included a temperature of 300C., a weight hourly space ~elocity (WHSV) of 7.4, a molar feed ratio of toluene to ethylene of 5 and a ~tre~m time o~ one hour. The conversion of toluene obtained was 4.1 weight percent and of ethylene 24.1 weight percent. The ethyltoluene isomer mixture was found to contain 93.15 weight perccnt of para isomer and 6.85 weight perc~nt of the me~a i~omer.
Exam~le 3 Catalyst preparation HZSM-5 hav-ing a crystallite slze of 0.~2 to 0.05 microns wa~ mixed with 35 weight percent alumina binder and extruded to produce a 1.5 mm. cylindrical particle. A ten gram sample of this extrudate was soaked overnight at room temperature in a ~olution of 8 grams of 85%
phosphoric acid in 10 ml of water. The resulting product was filtered, dried at 120C. for about 2 hours and calcined at 500C. for approximately an additional 2 hours. Ten grams of the phosphorus impregnated extrudate was then soaked at room temperature overnight in a solution o~ 25 gram~
of magnesium acetate tetrahydrate in 20 ml of water. It was then filtered, dried at 120C. for about 2 hours and then placed in a furnsce at 500C.
for approximately 2 hours~ The resulting product contained 4.18 weight percent phosphorus and 7.41 weight percent magnesium.
Toluen~ ethylation Toluene was alkylated with ethylene in the presence of the above ca~alyst. The conditions of reaction and analytical resnlts are summarizQd in Table 2 below.

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~r ~o g ~ o o ~ ~ C~l o ~ CO ~

o~U~ o,~ o CO o U~ o ~ o~

OcrU~
U~ .~. . . , ~Cr~ 0 ~ o `*
~ _, _I O~~1 ~~D O
r~

o ?^^ ~ 0 td ,~ ~d V h ~ O iq :Z ~ o 8 ~ v ~ ~

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Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. An ethyltoluene isomer mixture produced by ethylation of toluene and comprising at least 90 weight percent of para-ethyltoluene, 1 to 10 weight percent of meta-ethyltoluene and 0 to 0.1 weight percent of ortho-ethyltoluene, the ethylation conditions being such that said isomers are present in the aforementioned proportions in the direct reaction product of the ethylation, said isomer mixture being directly usable for preparing vinyl-toluene without further purification.

2. An ethyltoluene isomer mixture according to claim 1 in which the para-ethyltoluene content is from 90 to 99 weight percent.

3. An ethyltoluene isomer mixture according to claim 2 wherein the para-ethyltoluene content is from 97 to 99 weight percent and the meta-ethyltoluene content is from 1 to 3 weight percent.

4. An ethyltoluene isomer mixture according to claim 3 wherein the para-ethyltoluene content is from 98 to 99 weight percent and the meta-ethyltoluene content is from 1 to 2 weight percent.

5. An ethyltoluene isomer mixture according to any of claims 1 to 3 in which the ortho-ethyltoluene content is from 0 to 0.05 weight percent.