Патент USA US2411726код для вставки
Patented Nov. 26, 1946 '1 < 2,411,726 umrao's'ra'ras ' PATENT OFFICE PRODUCTION OF ABOMATIC HYDRO CARBON8 itonald Holroyd and David Hallam Primrose Peel, Norton-on-Tees, England, assignora to Imperial ’ Chemical Industries Limited, a corporation‘ of v Great Britain ,No Drawing. Application March 3, 1942, Serial No. 433,238. In Great Britain April 20, 1939 ‘ 15 Claims. (01.260-668) tween 250° C. and 400° C., the life of the catalyst This invention relates to the catalytic dehydro genation of saturated cyclic hydrocarbons having at least one ring containingsix carbon atoms is lengthened by carrying out the reaction in _ the presence of added hydrogen. with any given catalyst, reaction material, throughput and reaction temperature, as the amount of added hydrogen is increased the rate‘ ple, methyl cyclohexane and dimethyl- cyclo of catalyst deterioration decreases and ?nally hexanes, to the corresponding aromatic'hydro- I reaches» zero. With further increase in the carbons, for example, toluene and xylenes. amountof hydrogen added the rate of deteriora It is known to dehydrogenate pure hexamethyl , ene naphthenes and mixtures thereof into the 10 tion of catalyst ‘activity remains zero, but even (hereinafter referred to as hexamethylene ‘naph themes) or mixtures containing them for exam ’ tually a concentration of hydrogen, depending on corresponding aromatic hydrocarbons by heating the other conditions of operation, is reached at them in the presence of highly ‘active catalysts, which hydrogenation predominates over dehydro genation. It will be understood that such for example, rare metals. However, in carrying out this process it is found that the highly active catalysts rapidlyv deteriorate if the hexamethylene 15 amounts of hydrogen which cause hydrogenation to predominate over dehydrogenation should not naphthenes are accompanied by para?ln hydro carbons, and/or pentamethylene naphthenes (cyclopentane homologues), and/or unsaturated be added. . Generally it will be found desirable to add an amount of hydrogen whichprevents any loss of activity of the catalyst during a period of at and its compounds. The term “toxigen,” as em 20 least 100 hours. ployed in "the appended claims, is to be under hydrocarbons, such as oleiines, and/or sulphur ' . The amount of hydrogen required'to achieve stood as signifying one of those substances just enumerated which cause rapid ‘deterioration of such highly active catalysts in the stated dehy drogenation process. - any given diminution in the rate of deterioration ' of catalyst activity can be readily gauged by 25 small scale trials. It depends on the reaction material and the reaction conditions, and in We have now found that, in the ‘dehydro .creases with the temperature, with the concen- . genation to the corresponding aromatic hydro car-bons of hexamethylene naphthenes in mix; I trationv ofpara?ins, pentamethylene naphthenes, unsaturated hydrocarbons, sulphur and its com 30 pounds in the reaction material, and with the _ bons and/or pentamethylene naphthenes and/or working pressure. ‘ _ unsaturated hydrocarbons and/or small amounts It is desirable that sulphur and its compounds of sulphur or sulphur compounds by_‘treatment should be as low in concentration as possible in of the mixtures at temperatures not exceeding ‘the reaction vessel since, these have been found 450° C. in the presence of highly active dehydro genating catalysts, the rate of deterioration in 35 ,to have a very unfavourable effect on the reac tion. Unsaturated hydrocarbons should also be activity of the said catalysts can be diminished present in as low a concentration as possible. In and even reduced to zero by adding hydro-gen at addition, carbon monoxide, and any substances the commencement of the reaction zone. The capable of giving rise to the same under the re hydrogen to be added may be obtained from external sources or may be that previously pro 40 action ‘condltions, for example carbon dioxide, oxygen or steam, as well as ammonia, and other duced in the dehydrogenation itself, after sep nitrogen compounds, should be kept low in con aration‘ from the other reaction products, for centration or removed entirely from the hydrogen example byv cooling. According to the invention, therefore, in a 45 fed to the reaction since‘these also have been found to have an unfavourable effect on the re process for the dehydrogenation to aromatic hy~ action. If desired, the reaction material to be drocarbons of the corresponding hexamethylene dehydrogenated and/or the hydrogen to be added naphthenes in a mixture containing also para?in ‘may be subjected to a preliminary treatment to hydrocarbons and/or pentamethylene hydrocar remove constituents harmful to the catalyst, or bons and/or unsaturated hydrocarbons and/or 50 to reduce their concentration. sulphur or sulphur compounds, in the presence of ' The preliminary treatment of the reaction ma~ I a catalyst consisting of or comprising at least one terial to remove sulphur may consist in subjecting of the metals of group VIII'of the periodic sys the crude mixture in the vaporphas'e to treatment tem excepting iron, cobalt and nickel, supported ~ with hydrogen in the presence of a mild hydro on activated carbon, maintained at a temper tures of the same containing parail‘ln hydrocar ‘ ature not exceeding 450° C. and preferably be a 55 genating catalyst whereby sulphur compounds 9,41 1,790 4 are converted into hydrogen sulphide which is then removed from the hydrocarbons in any con one or more stages, with or without recycling a proportion of the products. venient manner. Such a preliminary hydrogena tion treatment also serves to decrease the amount of unsaturated hydrocarbons in the mixture 5 which have been found to have a detrimental effect on the life. of the catalyst. It is pre ferred to employ for this preliminary treatment a hydrogenating catalyst which is also capable of absorbing the hydrogen sulphide so that the va pours from the preliminary hydrogenation stage can be passed to the dehydrogenation stage without condensation which would otherwise be necessary in order to separate the hydrogen sul 15 phide from the hydrocarbons. The highly active dehydrogenating catalysts employed according to the invention may be pre pared in any known manner, for example in the case of platinum supported on activated carbon, Example 1 ~ A petrol from the hydrogenation of a middle oil contained by weight 5.9% aromatics, 42.5% para?in hydrocarbons, 35.5% pentamethylene naphthenes, and 16.1% of hexamethyiene naph thenes, This petrol was distilled to give 44% by weight of a fraction boiling up to 95° C. and 56% of a heavier fraction boiling above 95° C. The separation into two fractions concentrated 90% of the hexamethylene naphthenes present in the total petrol into the heavier fraction, while this fraction only contained 25% of the para?ln hy 'drocarbons present in the total petrol. The heavier fraction boiling above‘ 95° C. contained 8%‘ aromatic hydrocarbons, 19% para?ln hydro carbons, 747% pentamethylene naphthenes and the latter may be impregnated with a solution of 20 26% of hexamethylene naphthenes. The heavier fraction was then subjected to a chloroplatinic acid, dried and reduced in a stream of hydrogen, preferably in the reaction vessel it self. The dehydrogenation is preferably carried out preliminary treatment for the removal of sul phur compounds‘ by passage with hydrogen, in the vapour phase and at atmospheric pressure, at atmospheric pressure, but pressures higher 25 over a mildly h'ydrogenating catalyst consisting of a mixture of zinc oxide and nickel made by than atmospheric may be used if desired. The reduction in hydrogen at 400° C. of a mixture of hydrogen pressure, however, must obviously not 1 part of zinc carbonate to 24 parts of nickel car be so great as to cause hydrogenation to pre bonate. The treatment was carried out at a tem dominate over dehydrogenation. perature of about 290° C. with a feed. rate of 0.5 The present invention is particularly valuable 30 kilogram/litre of catalyst/hour and a hydrogen for improving the anti-knock quality of petrols concentration of 150 cubic metres of pure hydro containing hexamethylene naphthenes. It is pos gen/ton of material treated. The hydrogen sul sible to treat the whole of a petrol by the process phide produced by the reaction was absorbed by of the present invention with this end in view, 35 the catalyst, which had to be removed from time but it is preferable to separate it ?rst into two or more fractions, one or more of which is richer > to time. The dehydrogenation treatment was carried in hexamethylene naphthenes than the original out over a catalyst’ consisting of 5% of platinum petrol, and then to treat the fraction or frac ,supported on steam-activated cocoanut-shell tions richer in hexamethylene'naphthenes by the 40 charcoal. It was made by impregnation of the method of the present invention. The products charcoal with a solution of chloroplatinic acid, of dehydrogenation may then be added wholly with subsequent reduction, after drying, at 350° or in part to the whole or part of the untreated ' C. in a stream of pure hydrogen in the reaction fraction or fractions. The petrol may be sepa vessel itself. _ rated into two fractions, the out being made at 45 The vapours of the heavier petrol fraction. a temperature between 80° C. and 120° C., for after pretreatment as described above, were then example 95° C. The higher boiling fraction passed over the above dehydrogenation catalyst thereby contains a larger proportion of hexa- . at atmospheric pressure and at a rate of 2.5 kilo methylene naphthenes and at the same time a grams/litre of catalyst/hour, together with 640 relatively smaller proportion of para?in hydro 60 cubic metres of pure hydrogen/ton of reaction carbons than the original petrol. By subjecting material. At a temperature ranging from 280° C. only the higher boiling fraction to dehydrogena to 320° C. through the catalyst, the whole of the tion the advantages as compared with treating 26% of hexamethylene naphthenes present in the whole petrol are that the quantity of reac-, this petrol fraction were dehydrogenated to the tion material. treated in the dehydrogenation 55 corresponding aromatic hydrocarbons. The va plant is smaller, more satisfactory operation of pours were then condensed, giving a dehydro the catalyst is obtained because of the smaller genated product which contained 34% aromatic amount of para?in hydrocarbons and that there hydrocarbons, 19% para?in hydrocarbons and is less’loss of low boiling constituents by entrain 47% of pentamethylene hydrocarbons. ment in the gas stream. The dehydrogenated product was then mixed 60 Separation of the petrol into more than two with the untreated fraction boiling below 95° 0., fractions is of advantage where it is desired to thereby giving a petrol which then contained 22% dehydrogenate the various hexamethylene naph of aromatic hydrocarbons as against the original thenes under different conditions, or to adjust 5.9%, while the octane number was then 80 as the characteristics of the ?nal petrol, or to ob 65 against an original 75. _ tain particular fractions of aromatic hydro‘ Dehydrogenation of the hexamethylene naph carbons. ' thenes to the corresponding aromatic hydrocar It is possible by the present invention to dehy bons is substantially the only reaction. Forma drogenate substantially the whole 0! the hexa tion of unsaturated hydrocarbons by dehydro methylene naphthenes in the reaction material, 70 genation of the paraf?ns or pentamethylene but obviously, where required, it is possible, by naphthenes was less than 1/z% of the reaction suitable selection of operating conditions to de¢ material, while less than 1% of the reaction ma ,hydrogenate any desired proportion of the hexa terial was broken down to hydrocarbon gases. methylene naphthenes in the reaction material. With the above amount of pure hydrogen The dehydrogenation may be carried out in added to the reaction material very satisfactory o 9,411,700 of hydrogen added, the higher this proportion the operation was obtained and the catalyst did not lower is the poisoning effect or a given amount .deteriorate over a period of 500 hours, dehydro genation oi’ the whole of the hexamethylene. naphthenes present in the reaction material be ing attained without any further adjustment oi’ the reaction conditions. ' or sulphur. We claim: ,. 7 a l. A process for the dehydrogenation to aro matic hydrocarbons or the corresponding hexa-v methylene naphthenes contained in a mixture - containing also at least one toxigen, which com prises separating from the mixture a relatively Example 2 Another petrol fraction containing 45% or heavy fraction richer in hexamethylene naph hexamethylene naphthenes, . which on testing 10 thenes than said mixture and, having an initial with mercury gave an indication of the presence boiling point between 80° C. and 120° C. and sub of sulphur, after a mild hydrogenation treatment jecting said fraction together with added hydro as described in Example 1 was passed over the gen at a temperature not'exceeding450“ C, to I , dehydrogenation catalyst of Example 1 under the conditions described therein, but with 380 cubic .metres of pure hydrogen added per ton reaction material. A 100% conversion of the hexameth ylene' naphthenes was obtained over a period of 100 hours.v Dehydrogenation treatment of the 15 the action of a catalyst containing at least one of the metals of group VIII of the periodic sys tem except iron, cobalt and nickel, supported on activated carbon, the proportion oi.’ hydrogen add ed being' suilicient to prevent substantial loss'oi' activity of the catalyst during a prolonged‘ op original petrol fraction without the preliminary - 2,0 erating period, but not suf?cient to cause hydro hydrogenation treatment to remove sulphur com . pounds gave only 80% conversion of the hexa methylene naphthenes present. - genation to predominate over dehydrogenation. 2. A process for the dehydrogenation to aro a The following data illustrate the e?ects of vari ations in the amount of added hydrogen and in ' the amount of sulphur compounds present. (1) Effect of varying the amount of added hydrogen . With the same reaction material described in Example 1, and the same catalyst and reaction conditions, no deterioration of the catalyst was matic hydrocarbons of the corresponding hexa methylene naphthenes contained in a mixture containing also a deleterious sulphur compound which comprises largely removing s'aid compound _- from the mixture and subjecting the residual mixture together with added hydrogen at a tem perature. not exceeding 450° C. to the action of a catalyst containing at leastione of the metals. of group VIII of the periodic system except iron, cobalt and nickel, supported on activated carbon, apparent over a period of 100 hours when 380 I the proportion of hydrogen added being suiiicient cubic metres of pure hydrogen were added per to prevent substantial lossof activity or the cat ton of reaction material instead of 640 cubic alyst during a prolonged operating period, but metres per ton. However, with 160 cubic metres "not su?icient to cause hydrogenation to pre per ton, the conversion of hexamethylene naph dominate over dehydrogenation. thenes to aromatic hydrocarbons fell from 100% - 3. Av process for the dehydrogenation to aro to 97% in 15 hours. With only 64 cubic metres matic hydrocarbons of the-corresponding hexa per ton the conversion fell to 79% in 2'7 hours, 41 methylene naphthenes contained in a mixture while with 32 cubic metres per ton the conversion fell to 64% in 18 hours. With no added-hydro gen the conversion fell very rapidly to 48% in 12 hours. In all cases where the catalyst is de teriorating due to insu?icient hydrogen there is some formation of unsaturated hydrocarbons which contribute to the deterioration oi’ the cat alyst. . containing also a deleterious sulphur compound which comprises subjecting the said mixture in the vapour phase to treatment with hydrogen in the presence of‘ a mildhydrogenating catalyst so 'as largely to convert the sulphur of said com pound into hydrogen sulphide, separating the hydrogen sulphide from the mixture and sub ' jecting the residualmixture together with added ' (2) Effect of d'i?erent amounts of sulphur compounds A petrol fraction boiling above 95° C. and con taining 30% of hexamethylene naphthenes, after it ‘had been subjected to the preliminary mild ' hydrogenation process for sulphur removal de scribed in the above example, was subjected to dehydrogenation. Complete conversion of the hexamethylene naphthenes to aromatic hydro , carbons was maintained under the reaction con 50 hydrogen at a concentration of between 200 and I 640 cubic meters per ton of mixture treated, and at a temperature not exceeding 450° C., to the action of a catalyst containing at least one of- the metals of. group VIII oi’ the periodic system ex ' c'ept iron, cobalt and nickel, supported on acti vated’ carbon. ‘ 4. A'process for the dehydrogenation to aro-~ matic hydrocarbons of the corresponding hexa methylene naphthenes contained in a mixture containing also at least one toxigen which com ditions described in Example 1 for a period of 60 prises separating from the mixture a relatively 200 hours, with the addition of 640 cubic metres of pure hydrogen/ton of reaction material, Ad dition of 0.0035% by weight of sulphur to the re action material, either as propyl sulphide or as thiopene, reduced the conversion from 100% to 11% in a period of 30 hours. In another case, the addition of 0.000'7% by weight of sulphur as propyl sulphide reduced . the conversion from 100% to ‘74% in 40 hours, while addition of heavy fraction richer in hexamethylene naph thenes than said mixture and having. an initial boiling point between 80° C. and 120° C. and sub jectin'g said fraction together with- added hydro-J gen at a temperature between 250° C. and 400° C. to the action of a catalyst containing at least one of the metals of group VIII of the periodic > system except iron, cobalt and nickel, supported on activated carbon, the proportion of hydrogen 0.008'l% of sulphur reduced the conversion to 70 added being suf?cient to prevent substantial loss 5% in the same period. In each case 640 cubic of activity of the catalyst during a prolonged metres of pure hydrogen per ton were added and operating period, but not su?lcient to cause hy-p, in each case the activity of the catalyst reached -drogenation to predominate over dehydrogena a constant level and did not fall'further. This _ level of activity is dependent on the proportion 75 tion. 9,41 1,786 7 . 5. A process for the dehydrogenation to aro matic hydrocarbons of the corresponding hexa methylene naphthenes contained in a mixture con taining also at least one toxigen, which comprises separating from the mixture a relatively heavy fraction richer in hexamethylene naphthenes containlng also at least one toxigen, which com prises subjecting the mixture in vapor phase, together with added hydrogen, at a temperature not exceeding 450° C., to the action of a catalyst containing at least one of the metals of group VIII or the periodic system except iron, cobalt than said mixture and having an initial boiling and nickel, supported on activated carbon, the point between 80° C. and 120° C. and subjecting proportion of hydrogen added being suil'lcient to said fraction together with added hydrogen in‘an prevent substantial loss Of activity 01' the cat amount of at least 200 cubic metres per metric 10 alyst during a prolonged operating period, but ton of the fraction and at a temperature not ex not sufficient to cause hydrogenation to predom ceeding 450° C. to the action of a catalyst con inate over dehydrogenation, taining at‘least one of the metals of group VIII 9. A process for the dehydrogenation to aro of the periodic system except iron, cobalt and matic hydrocarbons of the corresponding hexa nickel, supported on activated carbon, the pro 15 methylene naphthenes contained in a mixture portion of hydrogen added being su?icient to pre containing also at least one toxigen, which com vent substantial loss of activity oflthe catalyst prises subjecting the mixture in vapor phase, to during a prolonged operating period, but not suf gether with added hydrogen, at a, temperature ?cient to cause hydrogenation to predominate not exceeding 450° C., to the action of a catalyst over dehydrogenation. 20 containing at least one of the metals of group 6. A process for the dehydrogenation to aro VIII of the‘periodic system except iron, cobalt matic hydrocarbons of the corresponding hexa~ and nickel, supported on activated carbon, the ‘ methylene naphthenes contained in a‘ mixture proportion of hydrogen added being su?icient to containing also at least one toxigen, which com prevent substantial loss of activity ‘of the catalyst prises separatingfrom the mixture a relatively during an operating period of at least one hun heavy fraction richer in hexamethylene naph 25 dred hours, but not su?icient 'to cause hydro thenes than said mixture and having an initial genation to predominate over dehydrogenation. boiling point between 80° C. and 120° C. and sub 10. The process de?ned in claim 8 wherein the jecting said fraction together with-added hydro hydrogen is added in the proportion at; at least gen at a temperature not exceeding 450° C. to 200 cubic meters per ton of reaction ma erial. the action of a catalyst containing platinum sup 30 11. The process de?ned in claim 8 wherein the ported on activated carbon, the proportion or operating temperature is maintained between hydrogen added being su?icient' to prevent sub 250° C. and 400° C. ' stantial loss of activity of the catalyst during a 12. The process de?ned claim 9 wherein the‘ prolonged. operating period, but not su?icient to 35 operating temperature is in~m'aintained between cause hydrogenation to predominate over de ‘ hydrogenation. 250° C. and 400° C. ' ' 13. A process for the dehydrogenation to aro 7. A process for the dehydrogenation to aro matic hydrocarbons of the corresponding hexa matic hydrocarbons of the corresponding hexa methylene naphthenes contained in a, mixture methylene naphthenes contained in a mixture 40 containing also at least one toxigen, which com containing also a deleterious sulphur compound prises subjecting the mixture in vapor phase, to which comprises subjectingv the said mixture in gether with added hydrogen, at a temperature the vapour phase to treatment with hydrogen not exceeding 450° 0., to the action of a catalyst in the presence of a mild hydrogenating catalyst containing platinum supported on activated car so as largely to convert the sulphur of said com bon, theproportion of hydrogen added being su?i pound into hydrogen sulphide, separating the hy cient to prevent substantial loss of‘ activity of drogen sulphide from the mixture and subjecting the catalyst during an operating period of at the residual mixture together with added hydro least one hundred .hours, but not su?lcient to gen at a temperature not exceeding 450° C. to cause hydrogenation to predominate over de the action of a catalyst containing platinum sup 50 hydrogenation. porting on activated carbon, the proportion of 14. The process de?ned in claim 13, wherein hydrogen added being sufficient to prevent sub the hydrogen is added in the proportion of at stantial loss of activity of the catalyst during a least 200 cubic meters per ton of reaction ma prolonged operating period, but not su?icient to terial. cause hydrogenation to predominate over dehy 55 15. The process de?ned in claim 13, wherein drogenation. the operating, temperature is maintained be 8. A process for the dehydrogenation to aro tween 250° C. and 400° C. matic hydrocarbons of the corresponding hexa RONALD HOLROYD. methylene naphthenes contained in a mixture DAVID HALLAM PBIMROSE PEEL.