US2417454A - Synthesis of ethylated aromatic compounds - Google Patents

Description

B. B. CORSON ET m. 2,417,454

March 18, 1947.

SYNTHESIS OF ETHYLATED AROMATIC COMPOUNDS Filed Feb. 1s, 194:5

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Patented Mar. 18, 1947 smrmajsrs or Erma-rm) AROMATIC COMPOUNDS Ben Bennett Corson,

Pittsburgh, and Lynn Joseph Brady, Ross Township, Allegheny County, Pa.,

assignors, Company,

by mesne assignments, to Koppel-s Inc., a corporation of Delaware Application February 13, 1943, Serial No. 475,752

15 Claims. (oi. 260-671) The present invention relates in general to the catalytic preparation of ethylated aromatic compounds more especially of the benzene series and is more particularly concerned with the synthesis of monoand poly-ethylated benzene compounds from benzene hydrocarbons and ethylene, or a compound, such as ethanol, that yields ethylene under employed conditions of synthesis.

An object of the present invention is the provision of improvements whereby benzene, and hydrocarbons of the benzene series, can be easily and simply ethylated, in continuous operation, with either ethylene or ethanol, and whereby substantially only corresponding alkylated benzene hydrocarbons are produced; that is, benzene hydrocarbon compounds wherein the rade ical of alkylation has the same number of carbon atoms as the employed ethylene or ethanol.

A further object of invention is the provision of operating conditions and reactants ratios that are suitable for employing a known catalyst for the stated purpose.

A further object of invention is the provision of commercially feasible It has long been known in the art of petroleum refining that at elevated temperatures certain ant mixture of hydrocarbon compounds contained new products that boiled within a range .of temperatures which made them useful as motor fuels; it has also been further observed that,

investigated nor'were the alkylated aromatics product.

Ethylbenzene has more recently become a valuable and important commodity by reason of its easy dehydrogenation, with high yield, to give a styrene product that is easily reflnable or is sufliciently refined to be employed in the manufacture of one of the well-known forms of synthetic rubber. chemicals has morerecently come urgently to require a cheap, convenient, direct, and continudirect process that is adapted ly plentiful compounds, benzene and ethylene, or ethanol, either into monoor poly-ethylbenzene, is a distinct contribution to the art of synthetic destruction of reactants in secondary reactions such, for example, as pyrolysis, polymerization, or destructive alkylation, that would all reduce potential recoverable yields of the ethylated benzene or occasion subsequent complicated problems in the recovery and refining of the wanted pure product or products.

It has now been found that benzene can be directly and continuously alkylated, on a com,-

In consequence, the art of syntheticand without loss 350 0. Neither is the .ethylated merciai scale, with ethylene to give substantially only ethylated benzene in high yield when a mixture of benzene with at most about a molar equivalent of ethylene is passed, at relatively brief contact time, over a catalyst comprising a free acid of phosphorus, and especially over heattreated orthophosphoric acid that is supported on a granular carrier, it the said catalytic agent is maintained at a temperature of at least about 260 C. and the said compounds are maintained under superatmospheric pressure of at least ab out 200 pounds per square inch. importantly, it has been further discovered that, under the stated and similar conditions, the mixture of compounds emuent to the catalytic zone contain substantially only ethylated benzene and, except for a very minor portion, all of the original ethylene and benzene that have not participated in the said cthylation reaction, and thatgthe latter are consequently in condition, after cooling and separation of the ethylated benzene, to be returned to the catalytic zone for retreatment and conversion to ethylated benzene. Thus, ultimately, by means of the present invention, a given quantity of either benzene or ethylene, can be converted to ethylated benzene with only relatively minor loss of said reactants.

It is interesting here to note and to emphasize for those skilled in the art that under the abovestated relatively mild operating conditions and when using as a catalyst an acid of phosphorus. the ethylation of benzene with ethylene itself can be performed, simply, straight-forwardly, and continuously without of ethylene to longer chain aliphatic compounds of initial materials or the creation of complicated problems of product-separation and refining. The ethylation process of invention progresses without conversion of the ethylated benzene by pyrolytic decomposition into, for example, the toluene or xylene, or the like, such as is obta ned as his product by Komarewsky, J. Am. Chem. Soc., vol. 59. p, 2715, (1937) who produced toluene as the end-product of the alkylation of benzene with ethylene in the presence of an alumina-nickel catalyst at benzene obtained in the manner of Sachanen, Jour. Ind. & Eng. Chem., vol. 33, page 1543, (1941), who obtained some ethylbenzene along with toluene, xylenes, and propyland butyland amylbenzene by the high temperature alkylation of benzene with amylene in the presence of activated clay, the ethylbenzene being formed as a mere incident of destructive allsylation of benzene with amylene. Ipatiefi, Pines and Komarewsky, J our. Ind. 8; Eng. Chem., vol. 28, p. 222-3, (1936), show that phosphoi'ic acid, in liquid form, is operative after twelvehours of batchwise treatment, to convert benzene, that'is sealed in an autoclave, into ethyl ated benzenes by means of ethylene. From the crude product of the reaction they were able to isolate several ethylated benzenes by a plurality of repeated, careful fractionations. The nature of the other and'associated compounds in their crude reaction-product was not determined, but

they probably belonged to the aliphatic and cyclic series of compounds because it is known that by treating ethylene alone with that catalyst which is also employed by the present inventors, such aliphatic, cyclic and the like compounds are formed, as is shown by Ipatieif and one of the present co-inventors in J our. Ind. 8: Eng. Chem., vol, 2 8,p. 860 (i936).

. According to the'present invention, ethylation detectable polymerizationof benzene and other aromatic compounds is effected by continuously flowing a mixture thereof with ethylene or ethanol over a catalyst that is formed by the deposition of preferably orthophosphoric acid on an inert carrier support such as Sil-O-Cel, 'Celite', or kieselguhr for example,

said mixture containing not substantially more, and preferably substantially less, than a molecular equivalent of ethylene, or ethanol and said catalyst being maintained at a. temperature of at least about 260 C. and the reactants at a pressure of at least 200 pounds per square inch. The said catalyst can be employed as a granular stationary mass or bed, or it can be continuously moved within or through the catalytic zone; and it is operative in either continuous or batchwise operation.

The yields of alkylated aromatic hydrocarbon produced in the practice of the present improvement, during a single pass of the ethylene-benzene mixture over the catalyst, vary with the temperature of thecatalyst,-the employed contact time, the ratio of benzene to alkylation agent and with the system pressure. It has been found that catalyst temperatures of from about 260-300 C. give good conversions of benzene and ethylene, or ethanol, to ethylated benzene per single brief contact with the catalyst. It can, in general, be said that, other things being substantially equal, when the temperature of the catalyst is between 260-300 C., an increased conversion of ethylating agent to alkylated aromatic per pass of reactants mixture thereover results from increasing, either the contact time of such mixture with the catalyst, the ratio of benzene to alkylaticn agent, or the vapor pressure in the process-system, as will be evident from the hereinafter-given specific examples. Lower ratios of benzene to ethylating agent favor the formation of poly-ethylated benzenes. If the molar ratio of benzene to ethylene in the employed mixture of reactants is reduced to less than about 1:1, objectionable polymerization of ethylene with itself takes place with the consequent formation of unwanted compounds that are, for'the present purpose, wasteful of the alkylating component.

Conversions of ethylene to ethylated benzene amounting to from 23-50% per pass of a. mixture of refined ethylene and benzene over the catalyst have been obtained at contact times of respectively 14 to (51 seconds, when the catalyst was at a temperature of substantially 300 0.; conversions of over 70% of the ,ethylene have been obtained at the same said catalyst temperature and at a contact time of about seconds when the benzene to ethylene ratio was as about 1521.0. No evidence of the presence of substantial amounts of compounds of the type that could be produced by mere polymerization of ethylene to aliphatic compounds, or-the like, of higher molecular weight, was detected in the reactionproducts issuing from the zone of catalysis.

Exclusive of the ethylated benzene and the unreacted benzene itself, the gaseous and vaporous mixture effluent to the catalytic zone comprises over 9.? of unreacted ethylenefabout 2.3% of C3 and C4 hydrocarbons and substantially all of which were in the original ethylene employed, and about 0.3% of such permanent gases as hydrogen and methane. Thus, the ethylene not utilized for ethylation of aromatic hydrocarbon is in conditionto be recycled directly to the catalytic zone with make-up that alkylated products of unwanted constitution will be produced and which could'present diiiiethylene without fear I cult problems in the refining of the wanted ethylated benzene. The unreacted ethylene can of course, if preferred, be refined, for example, by low-temperature fractionation, or the like, before it is recycled to the catalytic zone, for the purpose of removing its very minor content of other constituents and avoiding their possible accumulation in the process-system. There is evidence, however, that such step would be only rarely required, if ever. It is preferable but is not necessary-to employ refined ethylene for the present improved process. It is, however, important to employ ethylene that is substantially free of olefines having a higher molecular weight, because, at the said favorable conditions for ethylenic alkylation, they exhibit a tendency either preferentially to react with the benzene, or to polymerize with themselves, or to pyrolize indefinitely as do also any products of their direct alkylation of the benzene; they thus can produce products having lower specific gravity than the ethylated benzene, and pyrolysis gases formed therefrom are of such mixed and indefinite constitution that their direct recycling can lead only to production of a confused mixture of alkylated aromatics. The presence of hydrogen or methane in the ethylene is not deleterious, but if higher molecular weight olefines are present, they tend to make unpredictable the identity of .the specific compounds that are synthesized by operation of the presentimproved process. It can in general be said that 6 produced by practice of the and some poly-ethylated benzene even at very high ratios of benzene to ethylenejor ethanol,

- in the admixture carried over the catalyst mass.

molecular 'weight or when alkylating benzene with any specific ole- .fine to obtain an alkylated benzene having a radical of alkylation corresponding to said specific oleflne, the employed olefine shouldbe substantially free of other olefines, or the 'ke, that exhibit greater tendency to unite with the benzene, if complicated recovery, purification, and even insoluble refining problems are to be obviated.

The employed ethylene can have any known source. It can, for example, be obtained from coke-oven gases or petroleum refinery gases either by their rectification or any preferred selective removal of other associated and interfering constituents. It may be also produced by the dehydration of ethanol, for example, 'by' flowing the alcoholic vapor through comminuted coke or pumic stone carrying syrupy phosphoric acid (H3PO4) which is maintained at a temperature of approximately 300 0., as set forth in Backso-formed ethylene being thereafter introduced into the benzene flowing toward the aforementioned catalyst chamber for alkylating said benzene therewith. It has also been found that a separate step for the dehydration of the ethanol to ethylene is not necessary when the presently employed catalyst for the alkylation reaction is phosphoric acid supported on Sil-O-Cel. kieselguhr, or the like, but-rather that, at an effective temperature of about 300 C. for carrying out the alkylation of the present invention, the ethanol can be dehydrated in situ in contact with the benzene to be alkylated, and it is only necessary It is also possible nuclearly to ethylate', toluene, xylene, and thexlike, and also naphthalene or substituted derivatives thereof.

It is also advantageous to operate the present process at elevated pressures, as aforementioned; for example, when the benzene-to-ethylene ratio is respectively about as 2.5:1 and at a contact time of about 55 seconds with the catalyst maintained at about 300 0., 22% of the ethylene was converted into ethylated benzene at a pressure of 200 pounds per square inch, whereas at a pressure of.400 pounds per square inch, other operating conditions remaining substantially the same, the conversion of ethylene to ethylated benzene averaged over per pass for a continuous operating period of 24 hours.

The advantages of the present improvement and its features will be more clearly understood by reference to the accompanying drawing showing for purposes of exemplification a preferred apparatus and method in which the invention may be embodied and practiced but without limiting the claimed invention specifically to such illustrative instance or instances. In the single figure of the drawing, there is shown a diagrammatic eievational view, partly in vertical section, of said apparatus. It comprises essentially a well-insulated catalyst chamber Ill wherein there is supported a bed of granular phosphoric-acid catalyst prepared in the manner set forth in the hereinafter given Example 1. and columnar fractionating stills 20, 30, respectively for separating unreacted benzene and ethylene from processproducts that pass'from the catalyst-bed and for separating mono-ethylbenzene from benzene manufactured by the activity of the presently employed catalyst. The said stills 20, 30, are each formed of a plurality of superposed bubble-cap trays.

In the practice of the process, benzene stored in tank I l and supplied-thereto through valved line l2 from a source thereof, is drawn into pipe haus No. 1.402.336, issued January 3. 1922. the

to flow an admixture of benzene and ethanol alkylated benzene compreheated benzene l3 by pump l4 and by it forced under pressure into pipe 15, as indicated by the arrows, whence.

l6 of pipe-still H. In of benzene is continue thereto by the it passes into coiled pipe coiled pipe Hi, the stream ously preheated by' heat delivered combustion-products of fuel-gas burned at the nozzled end 'of fuel-gas delivery-pipe Ill. The so-preheated benzene thereafter passes into pipe l9 and after passing through regulating-valve I 9a, flows downwardly into the upper part of the tube Z'l forming the Walls of said catalyst chamber l0. Immediately before entering said tube, however, the preheated benzeneis admixed with ethylene delivered by pipe 22 and is apportioned in preferred amount and pressure to such benzene by valve 23. The ethylene arrives in pipe 22 from its storage-tank 24 where it is held, under sufficient pressure, by means of pump 25, after delivery to the latter through line 26, to deliver it in required proportions to the passing into the catalyst chamber.

In the insulated'catalyst chamber, the admixture of benzene and ethylene flows downwardly through the granular phosphoric-acid catalystbed contained therein and a portion of its ethylene and benzene contents is converted into ethylated benzene during its traversing thereof. Continuously leaving the lower part of the cataprocess both monopoly-ethyl- I ence of each other in BAlZdd one. This admixture passes through valved pipe 27 and is continuously discharged into the lower section of fractionating still 20 wherein, by means of heat supplied from indirect steam coils 28, tlie unreacted benzene and ethylene are fractionally distilled from the ethylated benzene which then flows through valved pipe 29 into receiver 3i therefor. The volatilized benzene and ethylene continuously pass upwardly through the .fractionating column and are cooled in the prescondenser 32'. This cooled and ethylene is then consaid condenser by pump mixture of benzene tinuously removed from i 33 in pipe 34 and by it increased in pressure sufilciently for it to flow into the downwardly extending section of said pipe 34 and to be discharged therefrom into admixture with the inflowing current of benzene continuously flowed, by the aforementioned pump Id, through pipe i and into preheating coils l6, and, in such admixture, the ethylene and benzene cooled in said condenser 32 again form a portion of the fiow of ethylenebenzene admixture continuously flowed into contact with the bed of catalyst in catalyst-chamber lfl.

The ethylated benzene, that is formed by the above-described synthesis and is separated from the said reactants in fractionating still 20, collects in the bottom of said still and in quantities controlled by the liquid-level control 35 of valve 35 of drain-pipe 29, passes into receiver 3! whence it is continuously removed by pump 31 and thereby forced into pipe 38 for delivery into the fractionating column of still 30 wherein the said ethylated-benzene product is continuously fractionated into mono-ethyland poly-'ethylbenzenes by heat supplied to indirect heating coils 39, the mono-ethylbenzene being collected 'as over-head condensate in water-cooled condenser 56 whence it isdrained by means of pipe 4| into a, receiver 42 and thereafter to storage means through valved pipe 63. The higher-boiling polyethyiated benzene product is separated as a liquid in the bottom of Still 30 and is flowed therefrom, through valve d3 of pipe 44 by liquid-level control 55 for said valve, into receiver 46 and thereafter through pipe 41 into a provided storage.

In the event that the wanted ethylated-benzene derivative is the mono-ethylated product, poly-ethylbenzene collected in receiver 46 can, instead of being sent to storage, be returned to the catalyst-bed by opening valve 48 in pipe 69 and by means of pump M be admixed with benzene delivered from storage tank II, the new admixture being thereafter preheated, as abovedescribed, in pipe-still l6, and passed to the catalyst-bed which also has the ability to transfer one or more of the ethyl groups from the previously formed poly-ethylbenzene to the newly introduced benzene and thus to convert. both compounds into mono-ethylbenzene. Or, if only poly-ethylbenzene is the wanted product of the synthesis, the hereinbefore mentioned mono-,

ethylbenzene .delivered to its storage through pipe 53 from receiver 42 can be returned in similar manner to the present improvement. and present in considerable detail operating conditions that have been found useful in practice. In the examples. the expression contact time indicates the time required to displace that volume of the ethyleneai'omatic hydrocarbon admixture present at any one instant in the void space of the catalyst-bed by another such volume oi the admixture when its volume is determined in accordance with the simple gas-laws at the employed temperature of the catalyst and the pressure on the admixture of reactants.

Example 1 Five hundred parts of 85% ortho-phosphoric acid were thoroughly mixed with 117.5 parts of Sil-O-Cel along with a small amount of water to facilitate their mixing. This admixture was then dried in a mufiie furnace at 275 C. for a total period of 28 hours after which it was screened in an atmosphere of relatively low humidity and the particles that passed through an 8-mesh screen and were retained on the 16-mesh screen were employed in the operations detailed in the catalyst prepared as spective molal ratio of 1.8:1 under a pressure of following examples. The resultant catalyst-contained phosphoric acid to the extent of 62%, ex-y pressed as P205.

Example 2 A mixture of refined benzene and ethylene, said ethylene being 96.5% pure and containing a total of about 2.5% of ethane and C3 and C4 I hydrocarbons along with 1% of a mixture of hydrogen and methane, was continuously floweddownwardly in vapor phase over a bed of the in Example 1 in the re- 200 pounds per square inch, the catalyst bed being maintained at a temperature of 300 C. and the contact time of said vaporous mixture with the catalyst being about 59 seconds. The reaction-products effluent to the catalytic zone the catalyst-bed in admixture with additional ethylene and be there further were cooled under pressure for condensation of the liquid products. The resultant gaseous and liquid mixture was then passed through stabilizer apparatus for the separation from the liquid products of the gaseous ethylene and that which was dissolved in said products. The so-separated ethylene showed upon analysis a purity'in excess of and was immediately returnable to the inlet of the process without further treatment. With each pass of the benzene-ethylene mixture over the catalyst bed, 22.6% of its ethylene component was converted to ethylated benzene which wasv easily separated in high purity from the unreacted benzene by simple fractionation in which the ethylated benzene was collected as the distillation residue; The so-recovered benzene was also in condition for recycling directly to the inlet of the process. The said distillation residue was then further fractionally distilled to a vapor temperature of C. and

thereby separated into two fractions; 1. e. a distillate and a distillation residue. of mono-ethylbenzene boiled mainly at 133 0.,

uncorrected, and had a refractive index of 1.4957. N ,The distillation residue, rconsisting maim 1;. 1y of po1y-ethy1benzenes,had arefractiveindexn The distillate wardly over a bed of the catalyst prepared as in Example 1, in the molal ratio 01' respectively 3.6:1. The contacttime of the said mixture with the catalyst, was increased from 59 to 86 seconds and the pressure on the vapors was increased from 200 to 400 pounds per square inch. The catalyst was maintained at 300 C. The average conversion of ethylene to ethylated benzene during this 16-hour period was 75%. The reaction products were separated as described in Example 2. The separated ethylene and benzene were again of such high purity that they were returnable to the inlet of the catalyst for re-treatment without concern that products other than ethylated benzene -would result from their employment. By simple fractional distillation ethylated benzene, containing monoand ratio respectively of 1.497

poly-ethylbenzene in the 1:1.2,and having a refractive index of N was recovered.

Example 4 The following delineated to show the results obtainable by the present novel process by varyingthe ethylene-toe benzene ratio while retaining other operating comparative process runs are conditions substantially the same. In the follow? ing two runs the 6-10. mesh size. The results represent average figures over a 24-hourperiod.

process was operated substantially in the manner described in Example 2. The phosphoric-acid catalyst, however, was of pounds of higher boiling The results set forth in the above-given examples clearly show that within the temperature range of activity of the said phosphoric-acid catalyst, increase of catalyst temperature, longer contact time of the reaction mixture of ethylene and benzene therewith, increase of catalyst, and increase of the -ethylene ratio in the reaction mixture, each severally and all collectively tend to increase the percentage of a given quantity of ethylene that is converted into ethylated benzene per pass of an admixture of benzene therewith into contact with said catalyst. The said'results also show that the greater the benzene-to-ethylene ratio in the initial reaction mixture, the less will be the amount of poly-ethylbenzene produced by the alkylation reaction.

It was further observed during the above-described investigation that whether or not the benzene-to-ethylene molal ratio, in the initial mixture of reactants, was as 1:1 or as 5:1, the unreacted' ethylene efliuent to the catalytic zone was always in excess of 95% purity, and that both it and the unreacted benzene were sufiiciently pure to be immediately returned to the catalytic zone for additional treatment. No olefinic compoint than ethylene benzene-to were ever detected, by manganate test, in the after their stabilizatio synthetic liquid products Molal Ethylene Rm seconds fi fi? poly-ethylbenzene A 270 '52 400 2.5 21 as B 270 55 400 -7.7 12.9

These runs A and B clearly show that, if desired, the ratio of monoto poly-alkylated benzene can be easily varie zene-to-ethylene ratio in the reaction mixture flowed through the catalyst bed; they further show that, other conditions being equal, the said increase of said ratio increases the percentage of ethylene converted to ethylated of the reaction mixture over the catalyst.

the variation in results that are obtained by merely varying the pressure under which the mixture of ethylene and benzene vapors yare flowed over the described phosphoric aci'd gee d by increasing the benbenzene per pass Example 6 I The present investigators also showed in the course of their studies that not only could the simplearomatic hydrocarbon, benzene, be ethylated under the above-described conditions but that an alkyl aromatic, for example toluene, responded to substantially the "same operating conditions to yield ethyl toluene.

A mixture of pure toluene and refined ethylene inthe mole] ratio respectively of 2.3 to 1 was continuously flowed for a period of'24 hours through a bed of the phosphoric-acid catalyst, also prepared as in Example'l, under a pressure of 400 pounds per square inch, the said reaction mixture being in contact with the catalyst bed, which was maintained at a temperature'of 300 alyst. 0., for about 47 seconds}. The reaction products Molal Ethylene 4 Contact Weight ratio 33 T., 0. time, P 5 :3 3%: 2 3x222 mono-ethylbenzen'e seconds m input h poly-ethylbenzene These runs clearly show that if the pressure on the reactants is raised from 200 to 400 pounds per square inch, other conditions ,being substantia lly equal, the conversion of ethylene to ethylated benzene is more than double I Comparison of runs A and C also shows that icubling the pressure on'the reaction mixture is ;ub stantially equivalent to reducing the reaction ;emperature of the catalyst about30 C.

upon analysis was 7.9 times the poly-ethyl toluene produced by the reaction. 1 I a Example 7 "The polycyclic aromatic hydrocarbon, naphthe potassium-perbenzene, pure naphthalene,

the molal ratio of reprepared as in'Example 1, under a' pressure of 400 pounds per square inch, a given quantity of the reaction mixture being in contact with the catalyst bed, which was maintained at a temperature of 300 C., for about 53 seconds. The reaction-products leaving the catalytic zone showed upon analysis that an average of 19.5% of the ethylene entering, the catalyst chamber was continuously employed for alkylation of both the benzene and the naphthalene and that the naphthalene was ethylated in preference to the benzene, 2.5% of the latter being converted toethylbenzene per pass whereas 12% of the naphthalene was ethylated to ethylnaphthalene of which less than one I tenth was in the form of poly-ethylnaphthalene. That portion of the ethylene which did not react with either benzene or naphthalene in the catalytic zone was of high purity and was suitable for directly recycling thereto to convert further quantities of benzene and naphthalene to ethylated derivatives thereof, and there was substantially no loss thereof in side reactions.

Example 8 In the following example, the employed ethylating agent was etha'nol instead of the ethylene used in the above-given examples. 3 v

A mixture of benzene and 95% ethanol, in the 'molal ratio respectively of 10:1, was continuously for about 96 seconds. The reaction products 3:1:1 was continuously flowed, for a 24-hour period, downwardly through a bed of the phosphoric-acid catalyst, also the catalyst-bed was maintained at a ture of from about 260 maximum temperature one time was 296 C.

C. to about 280 obtaining locally at and held at substantially 280 C. in order to-get benefit of the higher conversions of ethylene to ethylated benzene at this higher temperature. Adiabatic conditions were maintained in the catalyst chamber throughout. The treated benzene-ethylene mixture was preheated to substantially the above-mentioned temperatures before being brought into contact with the catalysts for conversion. The pressure on the process-products When operating with the catalyst at a temperaleaving the catalytic zone were substantially free of ethanol, an average of 29% thereof having been converted to ethylated benzene and there-- mainder into ethylene. Upon condensation and stabilization, as above described, of the reactionproducts they were separated into a liquid fraction comprising, monoand poly-ethylated benzene in the ratio, respectively, of 13:1, and a gaseous fraction consisting substantially only of ethylene which was useful for mixing with more benzene to synthesize additional ethylated benzene, in the manner described in the above examples, or for mixing with further quantities of benzene'and ethanol to form a preferred ratio thereof for introduction into the catalytic zone. It is interesting here to note that water formed by the dehydration of the ethanol to form ethylene, in situ in contact with the benzene to be ethylated, did not interfere, under the stated operating conditions withthe activity of the phosprocess. They can ture of 260 C., the average conversion of ethylene, in the ethylene-benzene mixture, to ethylated benzene was about 66%, whereas, at 280 C., the conversion was 86.5%. The separated ethylated benzene showed upon analysis'that it consisted of monoand poly-ethylated benzene in the ratio respectively of 20:1. Over 100 pounds of benzene were ethylated, as described, per pound of catalyst up to the time the run was discontinued, and there was stillv no marked reduction in its activity. A total of over 1600 pounds of ethylated benzene was so prepared. The recycled ethylene separated from the ethylated benzene showed only a very minor content of gases other than ethylene; that is, a small percentage of methane and ethane, and they con stituted impurities in the employed ethylene and do not represent side-reaction products of the process system at their rate of accumulation. The ethylated benzene showed substantially no high-molecular weight aliphatic compounds, either saturated or unsaturated, and no unsaturated aromatic hydrocarbons.

Example 10 .per square inchand at a contact time of 54 seconds, over the phosphoric-acid catalyst which phoric-acid catalyst, and the so-formed water I was easily separated from the above liquid fraction of the reaction-products and removed from the process system.

Example 9 was maintained at'a temperature of 300 C. The reaction products issuing from the catalyst chamber contained, in contrast to the above-given'examples a significant proportion of constituents that boiled both considerably below benzene it-- In another specific example, a mixture of benzene and ethylene in the respective molal ratio of 15:1 wascontinuously flowed downwardly through a bed of the phosphoric-acid catalyst,

self and also intermediate benzene and etbylbenzene. These constituents were not purely aro-1 matic in nature as is shown by a refractive index as low, as.1.438 N and a bromine number as,

high as .80.

When the, ratio of benzene to ethylene was tempera- C., the

Throughout the major, portionof the run the catalyst temperature was prepared as described in Example 1, the, said be easily vented from the sequent recovery and refining t l changed so that they were present in their admixture in the ratio respectively of substantially 1:2 and the admixture was processed substantially as above described, the proportion of nonaromatic constituents in the mixture issuing from the catalyst chamber was importantly reduced,

such constituents entirely disappearing when the benzene-to-ethylene ratio was altered so that they were present in substantially equimolecular ratio.

As shown by the above present improvement now makes possible the der the preferred conditions of operation, there is substantially no polymerization of the ethylene to purely aliphatic derivatives. Advantageously, there is neither significant pyrolysis either of the ethylene or of the aromatic hydrocarbon components of the reactants, nor of the wanted ethylthe appearance of ucts and could occasion diflicult problems of subof the wanted products, as well as being wasteful of reactants. The ethylene and aromatic hydrocarbon components of the reactants that do not take part in the said 1. A process for preparing predominantly only mono-ethyl benzene from a mixture of benzene tive of and substantially pure ethylene, said processcomprising: continuously and concurrently fiowing in admixture benzene and substantially pure ethylene, With the molar ratio of benzene to ethylene greater than 1:1, into contact with a that is maintained at a temsubstantially only ethylated benzene and predominantly only mono-ethyl benzene from said reactants in contact with said catalyst; continu- I ousiy displacing reactants from contact with said catalyst mass by aforesaid admixture flowing into contact therewith; and recovering monoethyl benzene from so displaced reactantsU 2. A process as claimed in claim 1, and'in 4. A process as claimed in claim 3 and in which the aforesaid admixture of pure benzene and ethylene is continuously passed through the catalyst in co-current flow.

5. A process of synthesizing an ethyl derivacompound therefrom, and recycling the residual ethylene to the alkylation zone.

6. A process as claimed in claim 5, and in which I the aforesaidadmixture of aromatic hydrocarbon and ethylene is continuouslypassed through the catalyst in co-current fiow. 7. A continuous process for contact with a solid phosphoric acid catalyst that is at a temperature between about 260 C. and 315 C. and under .pressure above 200 lbs. per square inch efiective at that'temperature for reacting said reactants to form mono-ethyl derivaromatic hydrocarbon and that is nents to be reacted into contact with the catalyst; recovering mono-ethyl derivative of arobon in admixture 7 thereby converting the former 1y ethylated thereof.

into substantially only turning the poly-ethylated aromatic hydrocar- 'with aromatic hydrocarbon into contact with said catalyst as aforesaid, and

into less extensivearomatic hydrocarbon. 10. A method as claimed in claim 7, and in which the aromatic component and the ethylene introduced to the catalyst as a preformed admixture in the molar ratio to be reacted within the range set forth in claim 7, and in which the ethylene component is introduced asethanol, and ethylene is formed in situ in the catalyst zone from the ethanol by dehydration 11. A process as claimedin claim 7, and in which the aromatic component and the ethylene component are introduced to the catalyst as a preformed admixture in the molar ratio to be reacted within the range set forth in claim 7, and in which the ethylene component is introduced as ethylene. l

12. An improved process for synthesizing predominantly only mono-ethyl derivative of aromatic hydrocarbon, comprising: reacting an admixture df substantially pure aromatic hydrocarbon with ethylene that is substantially free of olefine having a higher molecular weight while continuously passing in fluid phase in contact with a solid phosphoric acid catalyst that is effective to promote the alkylation of said aromatic hydrocarbon with said ethylene and that is non-volatile under the following conditions of temperature and premure; maintaining said mixture in contact with said catalyst for a period of 14 to 145 seconds, the catalyst at least about 260 C., the ratio of ethylene to aromatic at most not more than, a substantially equi-molecular ratio, and superatmospheric pressure between 200 and 900 lbs. per square'inch on said ethylene and aromatic component, while passing in contact with said catalyst; a substantial portion of and thereby convertin said admixtures content ethylated aromatic hydrocarbons and predominantly only mono-ethylated aromatic hydrocarbon; v

continuously passing the reacted .mixture con- 9 and. simultaneously sisting of predominantly only mono-ethylated I aromatic hydrocarbon, unconverted aromatic hywhich the aromatic drocarbon, and residual unconverted ethylene from contact with said. catalyst.

513. Amethod as claimed in claim 12, and in hydrocarbon is benzene.

claimed in claim hydrocarbon is toluene.

15. A method as claimed in claim 12, and in which the aromatic hydrocarbon is naphthalene.

BEN BENNETT CORSON. LYNN JOSEPH BRADY.

14. A method as which the aromatic REFERENCES crrEn The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name I Date 2,067,764 Ipatiefl Jan. 12, 1937 1,953,702 Davidson Apr. 3, 1934 2,005,861 Ipatlefi June 25, 1935 2,275,182 Ipatie'ff et al Mar. 3, 1942 r 2,290,211 Schaad July 21, 1942 2,141,611 Malishev Dec. 27, 1938 2,148,378 Malishev Feb. 21'," 1939 2,188,057 Malishev Jan. 23, 1940 2,329,858 Schmerling et al. Sept. 21, 1943 2,343,870 Kaplan Mar. 14,4944

FOREIGN PATENTS Number Country Date British Apr. 19, 1937 OTHER REFERENCES Oil 8: Gas Journal, M156, 1942, pages 14 and 15.

Pardee et al., Catalytic Alkylation of Benzene with Ethylene, Ind. 82 Eng. Chem., Mar. 1943, pages 273-278.

Sachanen et al., Ind. and Eng. Chem.,- vol. 33, pages 1540-1544, Dec. 1941.

12, and in

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