US2373062A - Production of ethyl benzene - Google Patents

Description

April 3, 1945. E, E STAHLY 1 2,373,062

PRODUCTION oF lETHYL BENZENE Filed Aug.` 1, 1941 B5 Wl/MWC? x Patented 3, 1945 PRODUCTION OF ETHYL BENZENE Eldon E. Stalily, Pittsburgh, Pa.,V asslgnor to Standard Oil Development Company, a corporation of Delaware Application August 1, 1941, Serial No. 404,985

4 Claims.

The present invention` is concerned with the manufacture of ethyl benzene. The invention is more particularly concerned with an improved process by which a maximum yield of mono-,ethyl benzene may be readily secured with minimum formation of undesirable poly-ethyl benzenes.

In accordance with the vpresent process benzene is reacted with ethylene in an initial stage under conditions to form mono-ethyl benzene. The re- -action product is' separated and the mono-ethyl benzene recovered. The poly-ethyl benzenes are then contacted in a secondary stage with additional benzene in the absence of ethylene to form an additional yield of mono-ethyl benzene. By operating in this manner a maximum yield of the desired product is secured with a minimum formation ofpoly-ethyl benzenes.

It is wellknown in the art to react benzene and etlnrlene under suitable conditions in the presence of various catalysts to form ethyl benzene. 'I'he desired product comprises mono-ethyl benzene. However, in these reactions, it is relatively difficult to control the reaction so that poly-ethyl benzenes are not formed. I have, however, now discovered a process by which a maximum yield of mono-ethyl benzene may be secured with a'minimum formation of undesirable poly-ethyl benzenes. My process may be `readily understood by reference to the attached drawing illustrating one embodiment of the same.

Referring specically to the drawing, it is assumed for the purpose of illustration, that the catalyst usedcomprises aluminum chloride and that the same isintroduced'into reaction zone I by means of line 2. ethylene is introducedinto the system by means of line 3 while the stream comprising benzene is introduced into the system by means of line A. 'I'he respective streams are passed through mixing zone 5 and introduced into zone I by means of jets or equivalent means 6. Temperature and pressure conditions within zone I are adapted to secure the maximumyield of mono-ethyl'benzene. In general, the temperatures are in the range from about 100 F. to about 200 F. and the pressures are sulcient to maintain' the constituents in a liquid phase. The reaction products are removed overheadfrom zoneI by means of line 1 and passed to distillation zone 8. Under certain conditions it may be .desirable to recirculate a portion of the overhead to reaction zone I by means of line 9 and pump Ill. Unreacted ethylene may be removed from the overhead by passing the reaction products to zas liquid separator 25 in which the ethylene is separated and removed by means of .line 26.

Temperature and pressure conditions in distillation zone 8 are adjusted to remove overhead by means of line Il, the unreacted benzene which is preferably recycled to zone I. Ethyl benzene isv removed as a side stream from distillation zone 8 by means of line I2 and handled as desired. The higher boiling constitutents comprising poly-alkyl benzenes are withdrawn from distillation zone Il by means of line I3, combined withl additional benzene which is introduced by means of line I4 and the combined stream thengpassed into reaction zone I5 by means of jets or equivalent means 6. For the purpose'of description it is assumed that the catalyst in zone I5 comprises aluminum chloride. It is also assumed that the catalyst utilized in zone I5 is removed from zone I and introduced into zone I5 by means of line I6. Fresh catalyst may be introduced into zone I5 by means of line I1.

The temperature and pressure conditions maintained in zone I5 are in the general range from about 100 to about 500" F. The pressure conditions are suicient to rmaintain the constituents in the liquid phase. The reaction product comprising ethyl benzene is removed overhead byineans of line II1 and introduced into distillation zone I8. Temperature and pressure conditions vare adjusted to remove benzene overhead from zone I8 by means of line I9 which benzene j -ze `may also be recycled to reaction 'zone I.

V The stream comprising wit. :thefethyl benzene removed by means of line.

' I2.`"`Th`e higher boiling hydrocarbonconstituents essentially i comprises reacting benzene with ethylene in aninitial stage, removing. the reaction products and separating the same into mono-ethyl benzene and into higher poly-ethyl V benzenes. The higher polyethylbenzenes are then reacted-in a secondary stage with an additional quantity 'ofxbenzene to form mono-ethyl .n

benzene. Y The catalyst employed in the respective stages may comprise any of the conventional Friedel- Crafts catalysts such as aluminum chloride, iron chloride, zinc chloride, and the various metallic halides. The amount of benzene employed with respect to ethylene in the initial zone may vary considerably. However, in general I have found that it is preferred to use a molar excess of benzene as compared to ethylene. For example, I have found it desirable to employ from about 25% to about 100% molar excess of benzene to ethylene in the initial stage. In the secondary stage it is likewise desirable to employ a molar excess of benzene, usually in the range from about 50 to 100% excess, based upon the polyethyl benzenes.

- 'Ihe operating temperatures in the initial stage may vary considerably but are generally in the range from aboutv 100 F. to about 200 F. Preferred temperatures are in the range from about 160 F. to about 170 F. The temperatures in the secondary stage are somewhat higher and are in the general rang'e from about 100 F. to about 500 F. Preferred temperatures for utilization in the secondary stage are in the range from about 130 F. to about 250 F. In general, the

pressures are sufficient to maintain the constitui ents in a liquid phase.

In order to illustrate my invention further, the following example is given which should not be construed as limiting the same in any manner whatsoever:

Example A particular adaptation of the present invention is in the case where an impure commercial benzene is used in the process. The fresh benzene is preferably introduced into reaction zone I5 and thus `given a pretreatment with partially spent catalyst in addition to effecting the reaction between benzene and poly-ethyl benzenes. The purified benzene is then recycled to reaction zone I. fresh catalyst is introduced into reaction zone I and only partially spent catalyst is employed in reaction zone I5. 'I'he reaction between benzene and poly-ethyl benzenes goes more readily than the reaction between benzene and ethylene, so that la less active catalyst and a benzene feed 'with some impurities may be used.

What I wish to claim as .new and protect by Letters Patent is:

1. Improved process for production of monoethyl benzene which comprises reacting benzene with ethylene in the presence of a Friedel-Crafts catalyst in an initial stage, separating the reaction product from partially spent Friedel- Crafts catalyst and segregating poly-ethyl benzenes therefrom, reacting said poly-ethyl benzenes in a secondary stage with additional benzene in the presence of the partially spent Friedel- Crafts catalyst in the absence of ethylene, whereby additional mono-ethyl benzene is formed, separating the reaction product from said secondary stage and recovering the mono-ethyl benzene therefrom.

2. Process as dened by claim 1 in which said Friedel-Crafts catalyst comprises aluminum chloride.

3. Process as deiined by claim l in which the temperature utilized in said secondary stage is from 30 to 50' F. higherthan the temperature Parts by weight -1 i Unreacted benzene 1446 Ethyl benzene 1102 Poly-ethyl benzenes 8'78Y The poly-ethyl benzenes were segregated and 500 parts by weight of the same containing parts by weight of mono-ethyl benzene and 465 parts poly-ethyl benzene and 734 parts by weight of unreacted benzene. Thus 57.8% of the polyethyl benzenes and 26.6% of the benzene were converted to mono-ethyl benzene in accordance with my process.

employed in said initial stage.

4. An improved process for the production of monoethyl benzene which comprises reacting benzene with *ethylene in the presence of a Friedel-Craftscatalyst in aninitial stage, separating the reaction product from theA partiallyspent catalyst and segregating poly-ethyl benzenes therefrom, reacting said poly-ethyl benzenes in a secondary stage with impure commercial benzene in the presence of said partially spent catalyst in the absence of ethylene, thereby converting part of the poly-ethyl benzenes to monoethyl benzene. separating the reaction product from said secondary stage,- recovering the monoethyl benzene and unreacted benzene therefrom and supplying said unreacted benzene to the ,initial stage for reaction with ethylene.

ELDON E. STAHLY.

In an operation of this character the l

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