US2892876A - Production of ethylbenzene - Google Patents

Description

June 30, 1959 v. HAENSEL PRODUCTION oF ETHYLBENZENEl Filed Nov. 2, 1956 UnitedStates Patent O PRODUCTION OF ETHYLBENZENE Vladimir Haensel, Hinsdale, lll., assignor, by mesne assignments, to Universal Oil Products Company, Des Plaines, lll., a corporation of Delaware Application November 2, 1956, Serial No. 620,004

5 Claims. (Cl. S260-668) The present invention relates to the conversion of hydrocarbons and is more specifically directed to the production of ethylbenzene from ethylcyclohexane and alkylcyclopentanes, and petroleum fractions containing the same.

The demand for ethylbenzene has been steadily increasing through developments in the chemistry of polymers, and-with the rapid growth of :the petrochemical industry. Ethylbenzene is almost exclusively utilized as the starting material in the production of styrene, which, it is well known, readily polymerizes into polystyrene and copolymerzes with other derivatives such as butadiene, coumarone, indene, etc.

Although ethylbenzene exists as a natural occurring component of coal tar, its recovery as a pure, highly concentrated product from the latter is not economically advantageous. Recent developments in the petroleum industry, however, have shown that the production of large 4quantities of ethylbenzene from various petroleum fractions is economically justified. Ethylcyclohexane, a precursor of ethylbenzene, exists in almost all full boilingrange (about 180 F. to about 450 F. or more) petroleum fractions. Existing in conjunction with ethylcyclohexane are other eight carbon atoms hydrocarbons such as normal-octane and its isomers as Well as cyclic compounds including xylenes, cyclohexanes, substituted cyclopentanes, especially mcthylethylcyclopentanes, etc. I have discovered a process whereby ethylbenzene is produced from such petroleum fractions in greater yields than heretofore have been obtained. The increased yields result from the utilization of my process with certain processing conditions and catalysts selected as hereinafter set forth.

The conversion of substituted cyclopentanes, such as methylethylcyclopentanes, to ethylbenzene involves the formation of an intermediate compound, ethylcyclohexane, which is in itself a precursor of ethylbenzene. This is illustrated by the follow-ing chemical equation, from which the hydrogen atoms have been omitted in the interest of simplicity:

The degree of conversion of the alkylcyclopentanes to ethylbenzene is, therefore, controlled in part by the rich in ethylcyclohexane, and the separate conversionV of a fraction which contains no direct ethylbenzene pre- 2,892,876 Patented June 30, 1959 ICC cursor, by operating in two diierent conversion systems, one under conditions wherein the direct ethylbenzene precursor, that is, ethylcyclohexane, is not permitted to undergo any substantial side reactions except to form ethylbenzene, while the second conversion system operates under conditions to allow the reaction to proceed to an equilibrium formation of ethylbenzene although the original charge stock to the second conversion system contains no direct ethylbenzene precursors such as ethylcyclohexane. By separating the two zones and operating under conditions suitable for this type of conversion, it is possible to obtain a higher yield of ethylbenzene than heretofore possible. In a system which is operated without separating the charging stock into two fractions the ethylcyclohexane conversion to ethylbenzene precludes the formation of ethylbenzene from the other possible sources, that is, from the indirect precursors of ethylbenzene. In fact, some of the ethylbenzene can be lost when the streams are combined by virtue of equilibrium requirements that only a small amount of ethylbenzene is tolerated in the total effluent at equilibrium.

An object of the present invention `is to produce ethylbenzene from petroleum fractions containing ethylcyclohexane, alkylcyclopentanes, and other C8 hydrocarbons. These petroleum fractions may be full boiling-range petroleum fractions having initial boiling points of about F., and end points of about 450 F. or more; they may be selected fractions comprising only those hydrocarbons containing 8 or more carbon atoms; or, they may be hydrocarbons contained within some narrow boiling range such as from about 200 F. to about 350 F. or more.

Another object. of the present .invention is to produce ethylbenzene from ethylcyclohexane and other C8 hydrocarbons -by subjecting them at selected conversion conditions to contact with a particular type of catalyst.

In one embodiment, the present invention is relative to a process for producing ethylbenzene which comprises separating a petroleum fraction containing ethylcyclohexane and alkylcyclopentanes into a heavy fraction containing ethylcyclohexane and a light fraction, sub- I'stantially free from ethylcyclohexane, containing alkylcyclopentanes and dimethylcyclohexanes. The heavy fraction is contacted with a first body of catalyst at conversion conditions to convert the ethylcyclohexane to ethylbenzene, said first body of catalyst comprising a platinum-group metal component. The light fraction is contacted lwith a second body of catalyst at conversion conditions to convert the alkylcyclopentanes such as the methylethylcyclopentanes to ethylbenzene, said second body of catalyst comprising a platinum-group metal component and combined halogen.

Another embodiment relates to a process for producing ethylbenzene which comprises separating a petroleum fraction containing ethylcyclohexane and alkylcyclopentanes into a heavy fraction containing ethylcyclohexane, and a light fraction substantially free from ethylcyclohexane, and containing alkylcyclopentanes and dimethylcyclohexanes. The heavy fraction is contacted with a rst body of catalyst at conversion conditions to convert the ethylcyclohexane to ethylbenzene, said first body of catalyst comprising alumina and platinum. The light fraction is contacted with a second body of catalyst at conversion conditions to convert the alkylcyclopentanes and other C8 hydrocarbons to ethylbenzene, said second body of catalyst comprising alumina, platinum and combined halogen, the platinum concentration in said second body of catalyst being greater than the concentration of platinum in said rst body of catalyst.

In a specific embodiment, the present invention provides a process for the production of ethylbenzene which comprises separating a petroleum fraction containing ethylcyclohexane and alkylcyclopentanes into a heavy fraction containing ethylcyclohexane and a light fraction substantially free from ethylcyclohexane and containing alkylcyclopentanes, contacting said heavy fraction with a rst body of catalyst comprising alumina, from about 0.01% to about 1% by weight of platinum and from about 0.1% to about 5% by weight of combined halogen, at a temperature of from about 600 F. to about 1050 F., a pressure within the range of from about 50 to about 1000 pounds per square inch, a liquid hourly space velocity (deiined as volumes of hydrocarbon charged per volume of catalyst) of from about 1.0 to about 10.5, and in the presence of hydrogen at a rnol ratio of hydrogen to hydrocarbon ot from about 0.5 to about 20, contacting said light fraction with a second body of catalyst comprising alumina, from about 0.02% to about 2% by weight of platinum, from about 0.2% to about 8% by weight of combined halogen, at a ternperature of from about 610 F. to about 1060 F., a pressure of from about 50 to about 1000 pounds per square inch, a liquid hourly space velocity of from about 0.5 to about 10, and in the presence of hydrogen at a mol ratio of hydrogen to hydrocarbon of from about 0.5 to about 20, and recovering the ethylbenzene produced from said conversions.

The charging stocks that may be converted to ethylbenzene in accordance with the process of the present invention comprise petroleum fractions containing ethylcyclohexane and allcylcyclopentanes as well as other hydrocarbons. It is within the scope of this invention to utilize a mixture consisting only of ethylcyclohexane and alkylcyclopentanes which minimizes the initial separation problems, although the charge stock will normally comprise a hydrocarbon fraction containing ethylcyclohexane, alkylcyclopentanes and other hydrocarbons, When the selected hydrocarbon fraction is obtained from straight-run gasoline, natural gasoline, or the like, the boiling range of the fraction will usually be within the range of from about 180 F. to about 450 F. or more. A hydrocarbon fraction having such a boiling range is commonly referred to as a full boiling-range hydrocarbon fraction. Nhen desired, the boiling range may be somewhat narrower. For example, a full boiling-range hydrocarbon fraction may be separated, prior to employing the process of the present invention, to obtain a heartcut having an initial boiling point of about 200 F. and an end point of about 350 F. containing ethylcyclohexane and its alkylcyclopentane isomers. Also within the scope of the present invention is the conversion of a hydrocarbon charge which is substantially free from both ethylcyclohexane and alkylcyclopentanes, since these materials will build up in the various ,recycle streams, hereinafter described, as a particular consequence of the present invention. Whatever the case, the ultimate hydrocarbon charge employed in the process of the present invention will contain ethylcyclohexane and alkylcyclopentanes.

The benefits derived from the process ot the present invention result from many reactions for converting ethylcyclohexane and alkylcyclopentanes to ethylbenzene. For example, ethylcyclohexane may be converted to ethylbenzene by dehydrogenation as illustrated by the following chemical equation (hydrogen atoms have been omitted for the sake of simplicity) The isomerization of alkylcyclopentanes, such as methylethylcyclopentane yields ethylcyclohexane as an intermediate which, in turn is converted to ethylbenzene by dehydrogenation, The isomerization of methylethylcyclopentane may be illustrated by the following chemical equation:

Other C8 hydrocarbons may be converted by dehydrocyclization; for example, normal octane and its isomers will undergo dehydrocyclization as illustrated by the following chemical equations:

lt is not intended, however, to limit the present invention to the reactions so described.

ln the case of the conversion of petroleum fractions containing both ethylcyclohexane and substituted cyclopentanes such as methylethylcyclopentane to ethylbenzene, the ethylcyclohexane is much more easily converted than the methylethylcyclopentane. At certain operating conditions the rate of conversion of ethylcyclohexane to ethylbenzene is much greater than the conversion of methylethylcyclopentane to ethylcyclohexane and subsequently to ethylbenzene. At other conditions, the rates may not differ to a great degree, however, in all circtunstances of operating conditions and charging stock, the conversion of ethylcyclohexane to ethylbenzene is always greater than the conversion ot methylethylcyclopentane and other C3 hydrocarbons to ethylbenzene. It is believed that in the conversion of alkylcyclopentanes to ethylbenzene, ethylcyclohexane is formed as an intermediate which is subsequently converted to ethylbenz'ene. The rate of conversion of alkylcyclopentanes to ethylben'zene appears to be controlled by the rate of conversion of alkylcyclopentanes and ethylcyclohexane.

At the operating conditions required for the conversion, the equilibrium between alkylcyclopentanes and ethylcyclohexane is strongly in favor of the alkylcyclopentanes. Thus, in order to convert the alkylcyclopentanes to ethylbenzene it is necessary to maintain a very low concentration of the ethylcyclohexane which can only be assured by a rapid conversion of the ethylcyclohexane to ethylbenzene. This would prevent any substantial pile-up of ethylcyclohexane which would shift the reaction such that the alkylcyclopentanes would have the tendency to be converted to undesirable parains rather than ethylbenzene.

The process of my invention provides a novel method for obtaining high yields of ethylbenzene by segregating the reactions, which have been previously described, into two separate, individual reaction zones. Thus, the hydrocarbon charge stock containing ethylcyclohexane and alkylcyclopentanes is separated into a heavy fraction containing ethylcyclohexane and a light fraction, substantially free from ethylcyclohexane, containing al` kylcyclopentanes. At atmospheric pressure ethylcyclohexane has a boiling point of 270 F. and the methylethylcyclopentanes boil at about 260 F. The preferred temperature for separating the total hydrocarbon fraction is from about 261 F, to about 269 F., although any temperature may be utilized which eects a heavy -fraction containing substantially all of the ethylcyclohexane and a light fraction substantially free from ethylcyclohexane and containing alkylcyclopentanes and dimethylcyclohexanes. Each of these fractions is then subjected to contact with a particular catalyst under conversion conditions which enhance the desired reactions. In the case of ethylcyclohexane-conversion to ethylbenzene, the most prominent reaction is dehydrogenation. Thus, both the operating conditions and the catalyst are chosen to enhance dehydrogenation and suppress other reactions. The conversion of alkylcyclopentanes to ethylbenzene is an isomerization reaction followed by dehydrogenation, which is enhanced by operating conditions and catalyst different from those utilized only for the conversion of ethylcyclohexene to ethylbenzene.

As hereinbefore set forth, the conversion of ethylcyclohexane to ethylbenzene is relatively rapid compared to the conversion of alkylcyclopentanes to ethylcyclohexane and thence to ethylbenzene. Thus, the operating conditions for promoting the former reaction may be less severe than those utilized for the latter reaction. The catalyst in both instances may be the same although the preferred method of the present invention utilizes different catalytic composites, each of which is specilically tailored to enhance particularly the aforementioned desired reactions.

The process of the present invention is specifically directed to operations where the catalyst in the reaction zones comprises a refractory inorganic oxide, combined halogen and a group VIII metal component. Suitable but not necessarily equivalent refractory inorganic oxides comprise alumina, silica, zirconnia, thoria, magnesia, etc. The preferred inorganic oxides are alumina, silica and zirconia, although it is understood that these do not necessarily yield equivalent results: combinations of two or more of the inorganic oxides named may be advantageously employed.

The halogen includes fluorine, chlorine, iodine or bromine; the preferred halogen, however, comprises Huorine and/ or chlorine. In general, fluorine appears to be less easily removed from the catalyst composite and, therefore, is preferred in many cases. It is understood that the halogen may comprise a mixture of two or more of the aforementioned halogens; a particularly preferred `mixture comprises fluorine and chlorine. The

Vhalogen is combined with oneor more of the other components of the catalytic composite and, therefore, is usually referred to as combined halogen.

Another component to be composited in the catalyst comprises a group VIII metal component, which component is a metal or a compound of a metal selected from group VIII of the periodic table. While platinum is the preferred metal, it is understood that other members of group VIII, particularly those members of the platinum group, are particularly suitable and may be advantageously employed. These other components include, although not with equivalent results, the metals or compounds of nickel, cobalt, palladium, iridium, etc., or mixtures of two or more.

A low-halogen content catalyst is utilized in the first reaction zone and a high-halogen content catalyst is employed in the second reaction zone. Such a method provides for a very high rate of conversion of ethylcyclohexane to ethylbenzene in the tirst reaction zone and also minimizes any undesirable conversion of ethylcyclohexane, such as ring-opening. In the second reaction zone a higher halogen content catalyst is employed to further the rate of conversion of alkylcyclopentane to ethylcyclohexane and then to ethylbenzene. As hereinafter set forth, the platinum concentration of the catalyst in the second reaction zone is greater than the platinum concentration in the first reaction zone. Thus, at least a portion of the ethylcyclohexane resulting from alkylcyclopentanes will be converted to ethylbenzene.

Although the platinum concentration of the two catalytic composite may be the same, it is preferred tohave the platinum concentration different in each zone and the concentration in the second reaction zone' at all A times greater than the platinum concentration in the rst reaction zone. As previously mentioned, the high platinum concentration -is desirable in the second reaction zone to further increase the yield of ethylbenzene by converting at least a portion of the ethylcyclohexane which results from the alkylcyclopentanes to ethylbenzene. Also, the high platinum catalytic composite is desirable due to the comparative diticulty of promoting the conversion of alkylcyclopentanes to ethylcyclohexane and thence to ethylbenzene with respect to the conversion of ethylcyclohexane to ethylbenzene.

The catalyst composite of the present invention may be made in any suitable manner including separate, successive or co-precipitation methods. Likewise, the refactory oxide may be prepared in any suitable manner', for example, alumina may be prepared by adding a suitable alkaline reagent such as ammonium hydroxide to a salt `of aluminum such as aluminum chloride, aluminum nitrate, etc., in an amount to form aluminum hydroxide which, upon drying, is converted to alumina. The alu mina may be formed into any desired shape such as spheres, pills, granules, etc. A preferred form of alumina is the sphere, and alumina spheres may be continuously prepared by passing droplets of an alumina sol into an oil bath maintained at an elevated temperature, retain'- ingr the droplets in the oil bath until the droplets set to hydrogel spheres. The spheres are continuously Withdrawn from the oil bath and immediately thereafter aged prior to being contacted with water or any other aqueous substance.

The halogen may be added to the catalyst in any suitable manner, and either before or after formation of the inorganic oxide. While halogen may be utilized as such, it is preferred that the halogen be added as an aqueous solution of the hydrogen halide. In the preferred method, the halogen is added to the refractory oxide before the other components are composited therewith. When alumina is the selected refractory oxide, the halogen is preferably incorporated into the alumina before forming into particles. This may be accomplished by the use of an acid such as hydrogen fluoride, hydrogen chloride, hydrogen bromide, and/or hydrogen iodide. In some cases volatile salts such as ammonium fluoride, ammonium chloride, etc. may be employed. In other cases the alumina may be prepared from an aluminum halide such as aluminum chloride, aluminum fluoride, etc.

As hereinbefore stated, the halogen concentrations of the catalytic composites are preferred to be different one from the other, and the halogen concentration of the catalyst in the second reaction zone is preferred to be greater than the halogen concentration in the rst reaction zone. However, it is understood that the catalyst employed in the first reaction zone need not necessarily contain halogen. The halogen which is added in any suitable manner Will comprise from about 0.1% to about 5% by Weight of the catalytic composite in the first reaction zone. The halogen concentration of the catalyst 1n the second reaction zone is designed to promote the more difficult reaction of converting alkylcyclopentanes to ethylcyclohexane, and subsequently to ethylbenzene, and as such will comprise from about 0.2% to about 8% by weight of the total catalyst, which concentration Will always be greater than the halogen concentration of the catalyst in the iirst reaction zone.

Platinum is a particularly desirable metal component to be incorporated into the catalyst since catalysts containing low concentrations of platinum are found to be very active, especially those catalysts utilized to promote the reactions previously described. In the preferred embodiment of the present invention the platinum concentration n the iirst reaction zone is from about 0.01%

to about 1% by weight of the catalyst, and the platinum concentration in the second reaction zone is within the range of from about 0.02% to about 2% by weight of the total catalyst.` It is further preferred that platinum concentration-in the second reaction zone be greater than `the platinum concentration of the catalyst in the first reaction zone. The increased platinum concentration in 4.the second reaction zone is desirable for converting the ethylcyclohexane, produced from alkylcyclopentanes to Vethylbenzene in order to inhibit the tendency for ethylvcyclohexane to pile up, the eiect of which has been .previously described.

The metals selected from the platinum group may be incorporated into the catalyst in any suitable manner. When platinum is the selected metal component, one method of introducing the platinum into the catalyst is .to form a separate aqueous solution of chloroplatinic acid, adding ammonium hydroxide to give a solution having a pH between the range of from about to about `10. This solution is then commingled with solutions of the ,other components of the catalyst. Although the platinum is preferably introduced as a solution of chloroplatinic acid, other suitable platinum solutions may be employed such as colloidal solutions or suspensions of v platinum cyanide, platinum hydroxide, platinum oxide, platinum sulfate, etc. In cases where the selected cornpound is not soluble in water at the particular conditions employed, other suitable solvents such as alcohols, ethers, etc. may be utilized. The platinum appears to enter into a peculiar association with the other cornponents of the catalyst and thereby serves to promote the desired reactions. While platinum is the preferred component, it is understood that other components selected from group VIH may be advantageously employed,

" The catalyst composite, before or after all of the components of the catalyst are present therein, is usually subjected to a high temperature treatment. The aluminahalogen composite may be subjected to a high temperature treatment or calcination before the other components of the catalyst are composited therewith. The `high temperature treatment is generally Yconducted at a temperature of from about 400 F. to about 1400 F. although the preferred range is from about 800 F. to yabout 1200 F.

The exact operating conditions are dependent upon the particular charging stock and, in effect, the ratio of ethylcyclohexane to alkylcyclopentanes contained therein. However, the operating conditions will usually be within the following ranges: temperatures of from about 600 F. to about l050 F. in the first reaction zone and 610 F. to about l060 F. in the second reaction zone, the temperature of the latter being at all times at least l0" F. greater than the temperature in the former. Operating pressures may be either identical or different for the two reaction zones, and will be within the range of from about 50 to about 1000 p.s.i. The reactions are preferably conducted in the presence of hydrogen which is produced and recycled within the process so that an extraneous source of hydrogen is unnecessary. The rate of hydrogen recycle may be either identical or different in the two reaction zones, and will generally be at a mol ratio of hydrogen to hydrocarbon of from about 0.5 to about in each. Although the liquid hourly space velocity (defined as volume of hydrocarbon charge per volume of catalyst) may be the same for both reaction zones, it is preferred that the liquid hourly space velocity over said first reaction zone be greater than the liquid hourly space velocity Aover said'second reaction zone. The liquid hourly space velocity through the first reaction zone will be within the range of from about 1 to about 1,0.5 and that through the second reaction zone of `from about 0.5 to about l0.

rIphe process of the present invention may be effected in any suitable equipment. The catalyst may be deposited as fixed beds in closed reactors wherein the hydrocarbons -to be treated are passed therethrough Vin either up- Yward, downward or cross flow. The catalyst may also Vbe, employed in a uidized type of operation, in which the catalyst and hydrocarbons are maintained in a state `of turbulence and where the catalyst is continually withdrawn and introduced into the reaction zone, or a fluidized, xed bed type of operation may be utilized in which the catalyst and hydrocarbons are maintained in a state of turbulence and where the catalyst is neither withdrawn from nor introduced into the reaction zone during the conversion operation. The catalyst may also be used in a moving bed type of process in which the catalyst and hydrocarbons are passed either in concurrent or countercurrent flow through the reaction zone.

The recovery of ethylbenzene may be effected by any suitable method. In one specific embodiment of the present invention the liquid product efuent from each of the two reaction zones are combined and introduced into a suitable aromatic recovery system. The ethylbenzene is recovered as a component of a highly concentrated aromatic product containing ethylbenzene, benzene, toluene, xylene, and other aromatics. The aromatic concentrate is then subjected to a suitable system for effecting the recovery of ethylbenzene therefrom. Any suitable method for recovering ethylbenzene may be employed; a particularly convenient method is to subject the aromatic concentrate to fractional distillation from which the ethylbenzene is obtained in a highly pure state. The aromatic concentrate containing ethylbene may be separated from non-aromatic components of the mixture of the liquid product eiuents, by any suitable method which produces a highly concentrated aromatic stream. Fractional distillation is not particularly preferred, although in some instances it may be used to advantage. The preferred method of separating the aromatic hydrocarbons from the non-aromatic hydrocarbons is by a form of solvent extraction Which utilizes a solvent having high solubilizing characteristics for aromatic hydrocarbons. It has been found that various glycols possess a great ainity for aromatic hydrocarbons and, of the glycols, diethylene glycol is preferred. Briefly, one method of the present invention encompasses combining the liquid product efuents from the reaction zones prior to separating the aromatic hydrocarbons therefrom. The aromatic concentrate is further treated to recover ethylbenzene. The non-aromatic hydrocarbons containing unreacted ethylcyclohexane and alkylcyclopentanes are combined as a recycle stream with the fresh hydrocarbon charge. The resulting mixture is then separated into a heavy fraction and a light fraction as previously described.

It is preferred, however, that the liquid product efiiuents from the reaction zones are subjected individually to separate aromatic recovery units. In this instance, the ethylbenzene contained in each of the aromatic concentrates is recovered in separate ethylbenzene recovery systems. The non-aromatic portion remaining from the heavy fraction is then employed as recycle to the reaction zone or may be in part recycled to conmiingle with the fresh hydrocarbon charge. Likewise, the non-aromatic hydrocarbons remaining from the light fraction may be recycled to the reaction zone and/ or in part recycled to combine with the fresh hydrocarbon charge.

The novelty and utility of the process of the present invention is further illustrated by the accompanying drawing. Several of the embodiments of the present invention are illustrated, although vit is not intended to limit unduly the present invention to those specifically shown. Modifications to the equipment, and variations in the process will become apparent through reference to the drawing as well as from the specification and example hereinafter set forth.

In the interest of simplicity, the valves, controls, heaters, coolers, and other 4similar refinements have beenlimited in the drawing or entirely omitted therefrom. These -are well known and evident, and need not necessarily be illustrated-or described in detail.

With reference to the drawing, the hydrocarbon charge comprising a mixture of hydrocarbons having a boiling range of from about 180 F. to about 450 F. or more is directed through line 1 and valve 2 into fractionator 3. vAs hereinafter described, the hydrocarbon charge may be combined with a rst non-aromatic recycle portion from line 25, a non-aromatic portion from line 60, and/ or a third non-aromatic recycle portion from line 49. Whatever the case, the hydrocarbon stream which enters fractionator 3 is separated into two portions. A heavy portion, being those hydrocarbons having boiling points of 261 F. or more, containing ethylcyclohexane is withdrawn through line 4 by pump 5 which discharges into heater 7 through line 6. Prior to heater 7, the heavy hydrocarbon portion is combined with a hydrogen-rich recycle gas stream, prepared as hereinafter described, from line 16. The hydrogen-hydrocarbon mixture is raised to the desired temperature in heater 7, and iS passed through line 8 into reactor 9.

An alumina-platinum catalyst, with or without cornbined halogen, is deposited in reactor 9 and the hydrogenhydrocarbon mixture is passed therethrough in downward ow, although, as hereinbefore described, upflow may be employed. In the case illustrated, the catalyst is deposited as a xed bed in reactor 9, but it is understood that the process may be effected in other types of operation.

The product from reactor 9 is removed through line 10, and directed through cooler 11 and line 12 into product separator 13. In separator 13, a hydrogen-rich gas is separated from the liquid hydrocarbon product, and 1s withdrawn through line 14 into the suction of compressor 15. A predetermined quantity of the hydrogenrich gas s discharged from compressor 15 into line 16 through which it is recycled to a point upstream of heater 7 where it is intimately mixed with the heavy hydrocarbon portion in line 6. Excess hydrogen formed in reactor 9 is withdrawn from the system through line 17 which contains valve 18. The excess hydrogen-rich gas stream withdrawn through line 17 may be sent to storage for future use, or may be employed directly in processes which require a high-purity hydrogen stream, but which do not form such hydrogen within the process.

A light portion of the hydrocarbon charge, being those hydrocarbons boiling below about 261 F., is withdrawn from fractionator 3 through line 29 by pump 30. Pump 30 discharges into heater 32 through line 31: prior to heater 32, the light-hydrocarbon stream is intimately mixed with a hydrogen-rich recycle stream from line 41. The hydrogen-hydrocarbon mixture is brought to the desired temperature inheater 32.and is directed through lineV 33 into reactor 34; v

An alumina-platinum-combined halogen catalyst is deposited in reactor 34, and `the hydrogen-hydrocarbon mixture is passed therethrough in downward ow as illustrated, or either upow or erossow, not illustrated. The effluent from reactor 34 is directed through line 35 through cooler 36, wherein the normally liquid hydrocarbons are condensed, and passed through 'line 37 into separator 38.

The hydrogen-rich gaseous phase is withdrawn from separator 38 through line 39 into the suction of compressor 40 which discharges a predetermined quantity of the hydrogen-rich gas through line 41 as a recycle stream to be mixed, upstream of heater 32, with the light hydrocarbon stream leaving'fractionator 3. The excess hydrogen-rich gas is withdrawn through valve 42 into line 43, and may be either transferred thereby to storage facilities, or immediately utilizedin some process which requires a high-purity hydrogen stream not produced within the process itself.

The liquid hydrocarbon product is withdrawn from separator 13 through line v19 and is directed into a suitable aromatic recovery unit 20. yThe non-aromatic hydrocarbon stream containing unreacted ethylcylohexane, is removed from aromatic recovery unit through valve 21 into line 22, from which `it is withdrawn through valve 24 into line 23 and is directed into line 4 to be mixed with the heavy-hydrocarbon stream leaving the bottom 10 of fractionator 3. A portion of the nou-aromatic hydrocarbons in line 22 may be withdrawn through line 25 and valve 26, and subsequently mixed with the hydrocarbon charge to fractionator 3 in line 1.

The aromatic concentrate produced in aromatic recovery unit 20, and which contains a substantial quantity of ethylbenzene is directed through line 27 into a suitable ethylbenzene recovery system 28, which recovery is usually accomplished by fractional distillation or solvent extraction, or some other suitable method.

The liquid hydrocarbon product is withdrawn from separator 38 through line 44, and is directed into a suitable aromatic recovery unit 45. The aromatic concentrate is withdrawn through line 52 into the ethylbenzene recovery system 28, previously described. The non-aromatic hydrocarbons containing unreacted alkylcyclopentanes are removed from Varomatic recovery unit 45 through line 46 which contains valve 47. The non-aromatic hydrocarbons are either passed through line 50 and valve 51 to be mixed with the light hydrocarbons p leaving the top of fractionator 3 in line 29, or through line 49 and valve 48 to be mixed with the hydrocarbon charge to fractionator 3 in line 1.

As illustrated in the drawing, an alternate scheme is presented wherein the liquid reactor eflluent from separator 13 is withdrawn through line 19 into line 53 containing valve 54, and is mixed with the liquid effluent from separator 38 which is withdrawn through line 44 into line 55 containing valve 56. The mixture is directed through line 57 into an aromatic recovery unit 58. The aromatic hydrocarbons are transmitted through line 59 into ethylbenzene recovery system 28.

The non-aromatic hydrocarbons are withdrawn from aromatic Vrecovery unit 58 through line 60 containing valve 61, and are directed to fractionator 3 in admixture with the hydrocarbon charge in line 1.

The alternate scheme may be utilized as such, or, as hereinbefore set forth, in combination with the previously described method. p In any case, the method employed is not intended to be removed from the scope of the present invention.

The following examples are given to further illustrate the process of the present invention, and to indicate the benefits derived from the process hereinbefore set forth. It is not intended, however, to limit the present invention to the operating conditions and catalyst employed.

- Example I A full-boiling range hydrocarbon charge was separated into two fractions: a heavy fraction containing ethylcyclohexane and other hydrocarbons having initial boiling points of 261 F. or more; a [light fraction containing alkylcyclopentanes and dimethylcyclohexanes, having initial boiling points of less than about 261 F. The-heavy fraction was 21.3% by volume of the total hydrocarbon charge.

The heavy fraction was passed through a first reaction zone containing a catalyst comprising alumina, 0.38% by Weight of platinum, 0.25% by weight of combined chlorine and 0.50% by weight of combined uorine. The operating conditions in the first reaction zone were: a temperature at the inlet to the reaction zone of 917 F., a pressure of 275 pounds per square inch (gage), a liquid hourly space velocity ofl 8, and a molal ratio of hydrogen to hydrocarbon of 6: 1.

The light fraction was passed'through a second reaction zone containing a catalyst comprising alumina, 0.38% by weight of platinum, 0.25% by weight of combined chlorine and 0.50% by weight of combined fluorine. The operating conditions -in the second reaction zone were: a temperature at the inlet to the reaction zone of 935 F., a pressure of 350 pounds per square inch (gage), a liquid hourly space velocity of 2, and a mola-1 ratio of hydrogen to hydrocarbon of 7:1.

The liquid product effluents from the first and second reaction Vzones were then separately subjected to solvent extraction, utilizing diethylene glycol, for recovery of the aromatic hydrocarbons. The aromatic concentrates Ywere then analyzed by infra-red analysis to determine the percentage of each of the hydrocarbon types contained therein.

The full-boiling range hydrocarbon charge was passed through a reaction zone containing the catalytic composite previously described. The operating conditions in the reaction zone were: a temperature at the inlet to the reaction zone of 935 F., a pressure of 350 pounds per square inch (gage), a liquid hourly space velocity of 2, and a molal ratio of hydrogen to hydrocarbon of 6:1. The aromatics contained in the liquid product effluent were recovered by solvent extraction, and analyzed for the percentage of each of the hydrocarbon types contained therein.

The results of the analyses of the aromatic concentrates from the heavy and light fractions, and from the full-boiling range hydrocarbon charge are given in the following table. There was an increase of 19% by volume in the quantity of ethylbenzene produced by the method of the present invention With respect to the quantity obtained from the total full bolllng range charge.

Full Light Aromatic Analysis, Volume Boiling Light Heavy and Percent Range Fraction Fraction Heavy Charge Based on Total Benzene 6.6 7. 8 0.2 6. 2 16.1 20.1 0. 2` 1G. 0 4. 0. 9 22. 9 5. 5 3. 2 3. 1 2. 6 3. 0 7. 2 6. 7 6. 7 (i. 7 4. 3. 9 5. 1 4. 2 higher aromatics 5. 6 0.8 18. 2 4. 4

Example I indicates the benefits of increased ethylbenzene production afforded through the use of the preferred embodiment of the present invention. As shown, the production of ethylbenzene was increased by 19% by volume, which increase is more outstanding with respect to commercial-size operations.

Example Il A full-boiling range hydrocarbon charge is separated into two fractions as in the previous example. The heavy fraction is passed through a first reaction zone which contains a catalyst comprising alumina, 0.38% by Weight of platinum, 0.25% by weight of combined chlorine and 0.50% by 4Weight of combined fluorine. The operating conditions in the first reaction zone are: a temperature at the inlet to rthe reaction zone of 917 F., a pressure of 275 pounds per square inch (gage), a liquid hourly space velocity of 8 and a molal ratio of hydrogen to hydrocarbon of 6: 1.

The light fraction is passed through a second reaction zone containing alumina, 0.75% by weight of platinum, 0.25% by Weight of combined chlorine and 0.75% by weight of combined fluorine. The operating conditions in the second reaction zone are: a temperature at the inlet to the reaction zone of 935 F., a pressure of 350 pounds per square inch (gage), a liquid hourly space velocity of 2 and a molal ratio of hydrogen to hydrocarbon of 7:1.

The liquid product eiuents from the rst and second reaction zones are combined, and the mixture is subjected to solvent extraction to remove therefrom the aromatic concentrate. The ethylbenzene contained in the aromatic conconcentrate is obtained by fractional distillation, and in greater yield than produced from processing the total petroleum fraction in a single reac- Ation zone.

The non-aromatic concentrate containing unreacted ethylcyclohexane and alkylcyclopentanes is recycled to combine With the full boiling range hydrocarbon charge for further separation and conversion.

The preceding examples illustrate the method of the present invention providing a process for producing ethylbenzene in greater yields than have been heretofore obtained.

I claim as my invention:

1. A process for the production of ethylbenzene which comprises separating a petroleum fraction containing ethylcyclohexane and methylethylcyclopentane into a heavy fraction containing ethylcyclohexane and having an initial boiling point of from about 261 F. .to about 269 F., and a light fraction substantially free from ethylcyclohexane, containing methylethylcyclopentane, and having an end boiling point of from about 261 F. to about 269 F.; catalytically contacting said heavy fraction, at a temperature of from about 600 F. to about 1050o F., with a first body of catalyst comprising alumina, from about 0.01% to about 1.0% by Weight of platinum and from 0.1% to about 5% by weight of combined halogen, at a pressure within the range of from about 50 to about 1000 pounds per square inch, a liquid hourly space velocity of from about 1.0 to about 10.5, and in the presence of hydrogen at a molal ratio of hydrogen to hydrocarbon of from about 0.5 to about 20.0; catalytically contacting said light fraction with a second body of catalyst cornprising alumina, from about 0.02% to about 2% by Weight of platinum, the concentration thereof being greater than the concentration of platium in said first body of catalyst, from about 0.2% to about 8.0% by Weight of combined halogen, the concentration thereof being greater than the concentration of halogen in said first body of catalyst, at a temperature of from about 610 F. to about l060 F., said temperature being atleast 10 F. greater than the temperature at the inlet to said first body of catalyst, a pressure of from about 50 to about 1000 pounds per square inch, a liquid hourly space velocity of from about 0.5 to about 10.0, said liquid hourly space velocity being greater than the liquid hourly space velocity through said second body of catalyst, and in the presence of hydrogen at a molal ratio of hydrogen to hydrocarbon of from about 0.5 to about 20; and recovering the ethylbenzene produced from said catalytic contacts.

2. The process of claim 1 further characterized in that the halogen in the first and second bodies of catalyst comprises chlorine.

3. The process of claim 1 further characterized in that the halogen in the first and second bodies of catalyst comprises uorine.

4. The process of claim 1 further characterized in that the liquid product effluent from the first catalytic contact is combined with the liquid product efuent from the second catalytic contact, separating the resulting mixture into an aromatic portion and a non-aromatic portion, treating said aromatic portion to recover ethylbenzene therefrom, combining said non-aromatic portion with the first-mentioned petroleum fraction for further separation and catalytic contact as aforesaid.

5. The process of claim 1 further characterized in that the liquid product effluent from the first catalytic contact is separated into a non-aromatic portion and an aromatic portion, treating said aromatic portion to recover ethylbenzene therefrom, combining at least part of said nonaromatic portion with said heavy fraction, subjecting the resulting mixture to catalytic contact as aforesaid, separating the liquid product effluent from the second catalytic contact into an aromatic portion and a non-aromatic portion, treating the aromatic portion to recover ethylbenzene therefrom, combining at least part of the nonaromatic portion with said light fraction, and subjecting the resulting mixture to catalytic Contact as aforesaid.

(References on following page) UNITED STATES PATENTS Shepardson July 16, 1946 Brandon July 10, 1951 5 Haensel et al Nov. 17, 1953 14 Murray et al. Sept. 14, 1954 Ruedislj Oct. 25, 1955 Oblad et a1. Nov. 15, 1955 Fragen et al. Dec. 13, 1955 Haensel et al. Feb. 12, 1957

Claims (1)

1. A PROCESS FOR THE PRODUCTION OF ETHYLBENZENE WHICH COMPRISES SEPARATING A PETROLEUM FRACTIO CONTAINING ETHYLCYCLOHEXNE AND METHYLETHYLCYCLOPENATANE INTO A HEAVY FRACTION CONTAINING ETHYLCYCLOHEXANE AND HAVING AN INITIAL BOILING POINT OF FROM ABOUT 261*F. TO ABOUT 269*F., AND A LIGHT FRACTION SUBSTANTIALLY FREE FROM ETHYLCYCLOHEXABNE, CONTAINING METHYLETHYLCYCLOPENTANE, AND HAVING AN END BOILING POINT OF FROM ABOUT 260*F. TO ABOUT 269*F.; CATALYTICALLY CONTACTING SAID HEAVY FRACTION, AT A TEMPERATURE OF FROM ABOUT 600*F. TO ABOUT 1050*F., WITH A FIRST BODY FO CATALYST COMPRISING ALUMINA, FROM ABOUT 0.01% TO ABOUT 1.0% BY WEIGHT OF PLATINUM, FROM FROM 0.1% TO ABOUT 5% BY WEIGHT OF COMBINED HALOGEN, AT A PRESSURE WITHIN THE RANGE OF FROM ABOUT 50 TO ABOUT 1000 POUNDS PER SQUARE INCH, A LIQUID HOURLY SPACE VELOCITY OF FROM ABOUT 1.0 TO ABOUT 10.5, AND IN THE PRESENCE OF HYDROGEN AT A MOLAL RATIO OF HYDROGEN TO HYDROCARBON OF FROM ABOUT 0.5 TO ABOUT 20.0; CATALYTICALLY CONTACTING SAID LIGHT FRACTION WITH A SECOND BODY OF CATALYST COMPRISING ALUMINA, FROM ABOUT 0.02% TO ABOUT 2% BY WEIGHT OF PLATINUM, THE CONCENTRATION THEREOF BEING GREATER THAN THE CONCENTRATION OF PLATIUM IN SAID FIRST BODY OF CATALYST, FROM ABOUT 0.2% TO ABOUT 8.0% BY WEIGHT OF COMBINED HALOGEN, THE CONCENTRATION THEREOF BEING GREATER THAN THE CONCENTRACTION OF HALOGEN IN SAID FIRST BODY OF CATALYST, AT A TEMPERATURE OF FROM ABOUT 610*F. TO ABOUT 1060*F., SAID TEMPERATURE BEING AT LEAST 10*F. GREATER THAN THE TEMPERATURE AT THE INLET TO SAID FIRST BODY OF CATALYST, A PRESSURE OF FROM ABOUT 50 TO ABOUT 1000 POUNDS PER SQUARE INCH, A LIQUID HOURLY SPACE VELOCITY OF FROM ABOUT 0.5 TO ABOUT 10.0, SAID LIQUID HOURVELOCITY OF FROM ABOUT 0.5 TO ABOUT 10.0, SAID LIQUID HOURLY SPACE VELOCITY BEING GREATER THAN THE LIQUID HOURLY IN THE PRESENCE OF HYDROGEN AT A MOLAL RATIO OF HYDROGEN TO HYDROCARBON OF FROM ABOUT 0.5 TO ABOUT 20; AND RECOVERING THE ETHYLBENZENE PRODUCED FROM SAID CATALYTIC CONTACTS.

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