Патент USA US2403757код для вставки
Patented July 9, v1946 7 2,403,757 "UNITED STATE s PATENT OFFICE 2,403,757 , PROCESS OF ISOMERIZING DIALKYL ‘ BENZENES. EdwardpD. Reeves, Cranford, N. J., assignor to Standard Oil Development Company, a cor poration of Delaware‘ N0 Drawing. Ap'pueation August 18, 1943, Serial No. 499,117 10 Claims.‘ (Cl. 260-668) , I Q The present invention relates to the isomeriza- . ‘ ‘The present invention resides in the prepara tion of aromatic hydrocarbons and pertains more tion of novel catalyst compositions which, upon being used in the heretofore-mentioned isomer particularly to the catalytic isomerization of ortho substituted dialkyl benzenes." ‘ It has been known that ortho xylene and other 301' ization reaction, obviate the dif?culties heretofore ' encountered in the known processes; Where a corresponding ortho substituted dialkyl benzenes liquid or vapor phase feed stock predominating could be isomerized to meta and para forms using in or composed solely of ortho dialkyl benzenes aluminum chloride as the catalyst and, if desired, is fediat a temperature between about 500° F. hydrogen chloride as the promoter. It has also and about 1150° F., at a throughput of between been known in the past to isomerize and dispro 10 about 0.4 and 6.0 liquid volumes of feed per vol portionate such ortho dialkyl benzenes under ~ temperatures of the order of 1300” F. to 1420° F. ume of catalyst mass per hour, in contact with a novel catalyst composition which may comprise in the absence of any catalyst. These methods a synthetic alumina-silica catalyst mass, su?i are, however, disadvantageous for several reasons. cient superatmospheric pressures are employed In the ?rst instance, where aluminum chloride 15 within the lower’ portion of this range, that is, is. employed, the catalyst is generally not recov at at'emperature below 650° F. to maintain liquid erable and considerable amounts of feed stock phase operation if desired. Superatmospheric were lost due to reaction with the catalyst to form pressures may also be employed where vapor complexes with aluminum chloride. Further phase reaction is contemplated, generally the more, by the complex formation over an extended 20 pressure amounting to from'1.5 to 10 atmospheres. period of time, large losses of aluminum chloride" occurred for ‘the same reason.‘ This, of course, necessitates replacement of the “ ‘catalyst mass The novel catalyst mass may be prepared in a number of various ways. Thus, for example, a silica gel may ?rst be formed by acidifying a dilute solution of sodium silicate with a moderate with aluminum chloride, or the complete shut down of a unit while fresh, catalyst mass is sub 25 excess of an acid such as hydrochloric acid stituted for the spent mass. In the case of the whereby a desired silica hydrogel is obtained. thermal isomerization of ortho xylene or other This may then be ?ltered and washed to remove ortho substituted dialkyl benzene, the fuel re the sodium ions therefrom, after which the gel quirements and the demand for special alloy steel may be washed with ammonia to free it of acid capable of withstanding high temperatures and 30 ions and thereafter-heated to a relatively low pressures necessitate the expenditure of large temperature to ‘evaporate the water. During the sums of money, and from the economic stand ?nal stages of heating, however, the temperature point such 'a'process is not particularly desirable, is gradually raised to a temperature of 800° F._ where commercial scale operations are contem~ and maintained at that temperature for a period plated. 35 of 3 hours to effect the ?nal drying of the silica It is an object of the present invention to carry gel. This procedure is described in the Patrick out the isomerization and disproportionation of Patent No. 1,297,794. To this silica gel produced ortho dialkyl benzenes to produce the correspond in accordance with this method or any other suit ing meta and para isomers in the presence of able method there is added alumina either as a novel catalyst compositions. It is a further object 40 gelatinous precipitate of aluminum hydroxide, as of the invention to obtain substantial amounts alumina hydrogel, alumina hydrosol or alumina of meta and para dialkyl benzenes by the isomer gel, or Activated Alumina, and‘the mixture is ' ization and disproportionation of the correspond commingled with heatingto produce the ?nal ing ortho dialkyl benzenes through the use of ‘dried product which serves as the catalyst in the novel’ catalyst masses which are relatively stable 45 present reaction. A homogenization treatment ‘during the isomerization and'are recoverable for of the ‘silica and alumina may be employed if regeneration and reuse in the process. It is a the hydrogel of alumina and the hydrogel of silica further object oi theinvention to conserve feed are ?rst mixed together then homogenized and stock and to prevent disintegration and degrada ?nally ‘dried to remove the water contained tion of the feed stocks and catalysts employed 50 therein. A suitable catalyst composition for use 7 in the isomerization and .disproportionation of in the present reaction contains about 87.5 weight ortho dialkyl benzenes to form the corresponding percent of silica gel. and about 12.5 weight per meta vand para' forms thereof. Other objects will cent of alumina. The mass may contain a total be apparent upon a fuller understanding of the ‘ of 15% water but in general a smaller percentage invention‘ herein‘ described. _ ' 55 vis desirable. 2,403,757 3 4 ization and disproportionation reaction to pro duce the corresponding meta and para dialkyl The catalyst may also be prepared in accord ance with the procedure outlined in U. S. appli benzenes. Feed stocks which are suitable for use cation No. 233,159, ?led October 4, 1938, in which in the reaction comprise any one or more of the a mixture of silica and alumina is formed by com following substances: ortho Xylene; 2-ethyl tolu bining the alumina with silica while the latter is ene; 1,2-diethyl benzene; Z-n-propyl toluene; 2 in hydrous form and thereafter dehydrating the isopropyl toluene, and similar Ca, Ca and C10 aro hydrous silica. matic ortho dialkyl benzene fractions. These A still further method for the preparation of may be obtained for use in the present process catalyst compositions useful in carrying out the process of the present invention resides in the 10 through the recovery of ortho Xylene concentrates or C9 aromatic fractions obtained in the catalytic impregnation of silica gel with a dry powdered hydroforming of petroleum fractions, or the feed alumina while the silica gel is in the form of hy stock may also be obtained from selected frac drogel and thereafter converting the said hydro tions of the required boiling ranges obtained in gel into a dry gel. A still further method of pre paring the novel catalyst composition resides in 15 coal tar distillations. The ortho Xylene concen trate may be easily isolated from the hydroformed impregnating a silica gel with an aluminum com product by efficient fractional distillation as may pound capable of being decomposed either by heat the C9 aromatic fraction which usually contains or by chemical reactioninto the oxide such as, ' substantial amounts of‘ ortho dialkyl benzenes. for example, aluminum nitrate, aluminum chlo Also suitable feed stocks ‘are obtainable by taking ride or aluminum acetate, followed by the suit 20 the selected cuts and fractions of aromatic type able treatment to reduce the compound to the from products obtained in the catalytic cracking aluminum oxide in situ. A solution of aluminum of petroleum re?nery fractions. The process ?nds sulfate may be added to a silica gel either in its greatest utility ,at the present time in using the form of the hydrosol or as the dried gel. The resulting mixture may then be soaked with am 25 '18 heretofore-mentioned feed stocks. It is rec ognized, however, that the isomerization reaction monium hydroxide to precipitate the aluminum involves the attainment of an equilibrium and hydroxide. The mixture then is washed free of that the process is also applicable to the isomeri acid and base ions and calcined at a temperature zation of meta and/or para dialkyl benzenes to of around 800° F. to give the required catalyst. produce the corresponding ortho isomers thereof. 30 Upon using aluminum nitrate, acetate or chlo Thus, too,,a meta substituted type of feed stock ride, the oxide is derived therefrom merely by yields ortho and para isomers; a para type yields heating the mass without resorting to the use of ortho and meta isomers. ammonium hydroxide to. convert it to the alumi In general, the temperature lies between about num oxide ?rst. Plural gels of alumina and sil 500° F. and about 1150° F., although it is preferred 35 ica, wherein both are formed simultaneously in to operate between about r750° F. and about 1025° admixture with each other, are contemplated as F. In general, the throughput rate is between well. about 0.4 and about 6.0 liquid volumes of feed Other methods of preparing the catalyst are stock per volume of catalyst per hour, but pref likewise known. However, the invention is not erably the rate of throughput lies between about limited to any speci?c method for preparing the 0.6 and about 4 liquid volumes of- feed stock per mixed silica-alumina catalyst mass. In general, volume of catalyst per hour. The process of the the mass may contain from 2:1 to as high as present invention is readilyadaptable to com 10:1 mols of silica per mol of alumina, although mercial operations involving a continuous vapor molar ratios outside of this range may likewise phase operation in which the vaporized feed stock be employed without appreciably affecting the ef is passed through a bed of catalyst mass main ?ciency of the catalyst for isomerizing the ortho tained under the required reaction conditions. dialkyl benzenes, as more fully hereinafter de This catalyst mass may be maintained on stream scribed. for between about 1 hour and about 20 hours, In addition to the use of catalysts composed 50 preferably between about 2 and about 12 hours, exclusively of silica and alumina as above de after which it is removed from the reaction and scribed, the invention also contemplates the use the catalyst mass is subjected to a short regen of catalysts containing, in addition to the silica eration treatment involving 1 to 5 hours, prefer and alumina, small amounts of metal oxides such ably between about 2 and about 3 hours, wherein as magnesia, thoria, zirconia and the oxide of boron. These catalysts may be prepared by the 55 air or any other gas containing free or uncom bined oxygen in dilute form is passed there addition of the corresponding nitrates, acetates through for a sufficient length of time and under or hydroxides of these metals to the hydrogels followed by the addition of ammonium hydroxide to obtain a mixed mass of hydrated alumina and/or hydrated silica coupled with hydrated thoria, hydrated zirconia, hydrated boron oxide or hydrated magnesia. The resultant admixture is ?ltered and dried and after drying to a tem perature of from 300° F. to 400° F. at ?rst, and ?nally at a temperature of 800° F. to 900° F., the resultant catalyst mass is ready for use. The per controlled temperature such that the carbona ceous impurities are burned from the pores of 60 the catalyst mass within the time required, after which the regenerated catalyst may be again placed on stream for effecting and activating the isomerization reaction. One of the chief ad vantages of the present process resides in the fact that the need for regeneration of the catalyst mass at frequent intervals is umiecessary because centage of the various metal oxides other than the silica and alumina present in the catalyst even at the relatively high operating temperatures desired. less of whether or not the present operation is car ried out using'a catalyst involving a ?xed bed, a moving bed or a ?uid catalyst type of technique. the coke formed on the catalyst mass is of the order of 0.6 weight per cent while ‘maintaining mass may range between about 3% and 10% based on the silica-alumina present, although percent 70 an ortho xylene conversion, of 60% or better. The process is readily adaptable for combination ages outside of these ranges may be employed if As previously stated, the resultant catalyst mass is employed in carrying out the isomerization of the ortho dialkyl benzenes by-a combined isomer with other petroleum re?ning operations regard 2,403,757 7 5 7 jThe process may be worked in conjunction with those processes previously mentioned which pro of meta and‘para xylenes are concerned, was-ob vide the source ‘of orthoxylene or other ortho dialkyl aromatics, such as hydroformingor cata tained when the per cent of ortho xylene under going reaction (conversion) was about 40%. This gave a selectivity of about 98. By selectivity is lytic cracking, and the Xprocessis particularly designed for use in combination with a catalytic meant the percentage of ortho xylene converted .togmeta and para xylenes and ethyl benzene. crackingvoperation since the same type of cata lyst may beused in both operations at substan tially thesazme temperatures and However, the utilityv of the invention includes the ' ‘formation. of lower ‘boiling aromatics such as single or common regenerator may be employed in the ?uid toluene or‘ethylbenzene, vthe concentration of catalyst technique common for both the catalytic which is. much, greater when higher conversion cracking operation andthe'isomerization reac ' leveIsare employed, The'pl'oducts need not be tion, the regenerated catalyst being fed, to each segregated into their'respective constituents since of the two units (from acommon source and the spent catalyst ‘from eachof ‘the two units being fed toa common regenerator for treatment with .15 air or other free-oxygen-contaim'ng gas as here practically all of them have excellent blending values for usein aviation fuels or in safety fuels. :. . . Weight per eent Weight per cent Weight per cent Weight per cent total liquid gas ‘ coke ' conversion vtofore described. The syntheticalmnina-silica catalyst may be employed not only in the form ofv granules of highly ~porous structure but it may be ?rst pilled with“ graphite or starch and'regenerated to render it even more highly porous, or. the catalyst may 6 The purest product. so far as the production 20 be pilled with. graphite orstarch’and used ,fresh ,in the [an-stream operation without ?rst regener ating the same, although it is preferred .to re generate the catalyst if in the pilling operation eithergraphite or starch has been added as a cohesion agent. 900° F. 975° F. 900° F. 975°F. 900°F. 975°F. racems .05 .1 -z .1 2 0. '0. 0. l. While :higher gas yields are obtained at the higher temperatures, the total liquid recovery is excellent in the entire temperature range shown. A series of experimental runs were made to de- '* The coke formation was so lowthat it was dif ?cult to determine whether the indicated inde 'termine the reaction variables employed from I pendence of temperature level was real or was ' which a number of observations can be made. At 'due' to an experimental error. It was found also a given throughput the. temperaturemaintained that not’ only did the selectivity decrease with increasing conversion but that this was not af fected by the temperature of the operation, the in the reaction zone has a pronounced effect on the conversion. For example, by increasing the temperature from 750° F. to 975°F. while main taining 0.6 liquid volume of ‘feed. per” volume of catalyst per hour the conversion was increased from 44% of the ortho xylene to 77% thereof. length of time of ion-stream. operation ‘of the catalystor-thé. throughput of.ther feed» stock ' through the catalyst mass. illustrated injithe following table: C8 aromatic fraction having a boiling range of 290-293" F. and of the heretofore-speci?ed com position through a closed reaction tube ?lled with about 200 cc. of analumina-silica catalyst whose composition was, roughly, 87.5 weight per cent usilicaand 12.5 weight percent alumina. The products were condensed and collected, theprod Weight 'per cent conver sion at the indicated am"), - ‘ .? 7: feeld. rate‘ ‘ ~ I _ 0.5‘ 1.8 _ ‘at 1140 52.5 The experimental ?ndings were obtained bypassing the vapor of a not analyzed for constituents rangingin boiling‘ ________________ __ 50 t2 , 52.5 point between about 265° F. and about 295°. F. H Arun carried out at 985° F. with a throughput It‘ is observed that at a given temperature the lyst perhour forv 12' hours produced a product ’-_ 79' 58 70 57.5 or‘ 0.6.liquid volume of feed per volumeof cata containing 4 weight percent ethyl benzene, 16 conversion decreases with increasing feed rate. weight per cent para xylene, 49 weight per cent Thus, at 1000° F. the conversion drops from 79% to 52.5%, while the liquid volume of feed stock per volume of catalyst per hour is increased from 0.6 to 4.0. In general, if reaction occurs, the meta xylene and 26 weight per cent unconverted ortho xylene. The yield of the product was about 755% based on the feed stock, with 12%1of the ' product in the benzene range and 3% accounted ?nal product in connection with the isomeriza for by gas and coke produced. tion and disproportionation of ortho xylene has the following weight per cent composition: Weight per cent 34 Ortho xylene Meta xylene A considerable number of experimental runs were carried out on two-hour reaction periods using a ?xed bed of 200 cc. capacity through / ‘which the heretofore speci?cally mentioned feed 49 Para xylene l2 5 65 Ethyl benzene ' The feed stock employed in this particular series of runs had the following‘ composition: stock was passed in the vapor phase. The prod ucts obtained varied in composition but gen erally ranged within the following composition: , Weight ' Per cent Ortho xylene _________________________ __ 26-42 7 Weight per cent Ethyl benzene _____________________ .__ 0 Para xylene _____________ _; ______ __‘__ Meta xylene ______________________ __ 0-1 6.5-7 Ortho xylene ______________________ _; 84-87.5 Total aromatics g __________________ __ 91-95 70 Meta Xylene 31-49 I Para xylene _____________ s. ___________ __ 3-17 Ethyl benzene ________________________ __ 0-5 Total aromatics produced _____________ __ 93-97 The particular percentage of constituents in the ?nal product as heretofore mentioned varies con 2,403,757 7 siderably depending upon the specific reaction conditions employed, but in general the product obtained will vary within the heretofore-men tioned ranges. The product may be isolated through fractional distillation means ‘or it may be ‘employed in the form produced directly as a blending agent in aviation or safety fuels. Ap preciable amounts of benzene and toluene were obtained where temperatures in the vupper ‘range or the heretofore-mentioned temperature ranges were employed with relatively ‘low rates of throughput. Thus, ‘for example, when employ» ing 0.6 volume ‘of feed stock per volume of catalyst per hour while maintaining a temperature of 1025° F. the result was the production of from group consisting of boron oxide, thoria, zirconia and magnesia. 4. A process which comprises isomerizing a feed stock comprising ‘essentially ortho ‘xylene at a temperature of about 985° F. at a throughput of about 0.6 liquid volume of feed per volume of catalyst per hour while in contact with a catalyst of silica gel containing alumina and at least one oxide taken from the group consisting of boron oxide, thoria, zirconia and magnesia. ’ 5. A process as in claim 4 wherein the vfeed stock is a Ca aromatic fraction obtained from a catalytic cracking of a petroleum oil. 6. A process as in claim 4'wherein the feed stock is a Ca aromatic fraction obtained from the hydroforming of ya petroleum fraction. 20% to 23% of toluene out based on the ortho '7. A process for the production of meta and 'xylene fed to the reaction zone. The same’ run para xylene which comprises contacting a feed produced, on the same basis, from 3.5% to ‘6% stock comprising‘ essentially ortho ‘xylene vat a of a benzene fraction. 'In a commercial opera temperature between about 750° F. and about 20 tion, however, ‘the use of a temperature of this 1025“ F. a-ta throughput of between about 0.6 and order would call for the use of a throughput of about 4.0 liquid volumes of feed stock per volume from 3 to 3%; liquid volumes of feed stock per of catalyst per hour with a catalyst comprising volume of catalyst per hour if it were desired to essentially synthetic alumina-silica gel, contain obtain as high a yield as possible of the meta and 25 ing at least one oxide taken “from the group ‘con para xylenes. ' sisting of boron oxide, thoria, zirconia and mag Having thus described and illustrated the nesia. nature of the invention, what is desired to be 8. A process as in claim '7 wherein ‘the catalyst secured by Letters Patent is: mass is employed in the reaction for a period of 1. .A'prooess for the isomerization vof ortho di alkyl benzenes which comprises contacting a feed 30 time between about \6 and about 12 hours and stock comprising essentially said ortho substituted dialkyl benzenes at a temperature between about 500° F. and about 1100“ F. with a catalyst mass regenerated with a gas containing free or uncom bined oxygen for between about 2 and about 3 hours prior to being re-employed for activating the isomerization reaction, and so employing said comprising a synthetic alumina-silica gel for -'a regenerated catalyst. . 35 suf?cient length of time to form substantial 9. A process for the production of 'meta and amounts of meta and para isomers, said gel conpara-dialkyl benzenes which comprises contacting taining at least one oxide taken ‘from the group a feed stock comprising essentially the corre consisting of boron oxide, thoria, zirconia and sponding ortho dialkyl benzenes at a temperature ‘magnesia. 2. In a process of catalytically isomerizing 1,2 40 between about 750° F. and about 1025*’ F. ‘at ‘a throughput of between about 0.6 and about 4.0 dialkyl benzenes to form the corresponding 1,3 liquid volumes of feed stock per volume of catalyst and 1,4 dialkyl benzenes under isomerization re mass ‘per hour with a, catalyst comprising es action conditions, the ‘improvement comprising catalyzing the said reaction ‘with a, catalyst mass sentially synthetic alumina-silica gel, containing comprising a synthetic alumina-silica gel, con 45 at least one oxide taken from the group consist ing of boron oxide, thoria, zirconia and magnesia. taining at least one oxide taken vfrom the group 10. A process as in claim 9 wherein the catalyst consisting of boron oxide, ‘thoria, zirconia ‘and magnesia. 3. A process which comprises isomerizing ortho xylene at a temperature between about 500° ‘F. and about 1'100° F‘. at a throughput of between about 0.4 and about 6.0 liquid volumes of ortho xylene per volume of catalyst mass per hour while in contact with ‘a synthetic alumina-silica mixed gel, containing at least one oxide taken from'the 55 mass is employed in the reaction for a, period of time between about 6 and about 12 hours and re generated with a gas containing free or uncom bined oxygen for between about 2 and about 3 hours prior to being re-employed for, activating the isomerization reaction, and so employing said regenerated catalyst. EDWARD D. REEVES.