US2397715A

US2397715A - Production of aromatic bodies

Info

Publication number: US2397715A
Application number: US426243A
Authority: US
Inventors: Weizmann Charles
Original assignee: Individual
Current assignee: Individual
Priority date: 1941-04-23
Filing date: 1942-01-09
Publication date: 1946-04-02
Anticipated expiration: 1963-04-02

Description

April 2, 1946- c. wElzMANN 2,397,715

PRODUCTION OF AROMATIC BODIES Filed Jan. 9, 1942 2 Sheets-Sheet 1 fig. 2.

Z122 o' @ZY/i301 @Za f/@J @AZ/naam,

April 2, 1945- c. WEIZMANN 2,397,715

PRODUCTION OF AROMATIC BODIES Filed Jan. 9, 1942 2 Sheets-Sheet 2 Patented Apr. 2, 1946 Charles Weizmann, London W. C. l, England Application January 9, 1942, Serial No. 426,243 In Great Britain April 23, 1941 (Cl. 26o- 668) 2 Claims.

This invention relates to aromatic bodies, namely, the production of aromatic hydrocarbons.

I have found that mineraloils, especially of relatively high-boiling range, are converted into aromatic hydrocarbons, to a considerable extent such of comparatively low-boiling point, such as benzene, toluene, xylenes and ethylbenzene. 'I'he process consists in passing the vaporised mineral oil over a metallic catalyst belonging to the group of metals catalysing hydrogenation and dehydrogenation reactions. Together'with gaseous products, such as hydrogen, methane, ethane, propane, butane and the corresponding oleilns,l a liquid is formed, which, apart from a very small amount of low-boiling (below 80 C.) highly unsaturated material, consists of aromatic hydrocarbons. It is assumed that the hydrocarbon molecules break down to very small units, such as olens, dienes and acetylenes. products are then dior polymerised. cyclised, if necessary, and dehydrogenated. All these processes appear to be catalysed by the same, abovementioned catalyst.

The process is a true cracking process, as its distinct feature is the production of substances chiefly of lower molecular size, compared with the starting material. As with other cracking proeesses, a certain part of the product has a boiling range higher than that of theinitial material.

Further I have found that a low-boiling bituminous shale oil (S-180 C.), and a low-boiling, low-temperature coal oil (o-180 C.), may be converted into aromatic hydrocarbons. It has now been discovered according to this invention that such conversion is not limited to oils such as shale oil and coal oil but that low-boiling The cracking petroleum fractions in general, natural or synthetic, provide good starting material for the process of aromatisation.

The product substantially consists of pure and easily separable aromatic hydrocarbons, notably benzene. toluene and a product, boiling at l36145 C., being pure ethylbenzene or a mixture thereof with small quantities of xylenes and styrene, depending on the nature of the starting material processed. With a straight-run gasoline of boiling range 10o-180 C., e. 8. under certain well-defined conditions, as much as 7% benzene, 14% toluene and 14% xylenes. containing ethylbenzene and styrene have been isolated, together with a minor quantity of higher alkylbenzenes, boiling between 140 and 180 C. (6%) and a heavy oil (5%), all the percentage figures being calculated on the feeding-stock. As the product obtained has a boiling range similar to that of the raw material processed, the new process may be described as "catalytic, aromatising reforming; it must. however, be remembered that part of the material is recovered as a high-boiling mixture of aromatic hydrocarbons, containing naphthaiene, anthracene andl other polycyclic compounds.

Part of the material is converted into gaseous products. The gases contain hydrogen, methane, ethane and ethylene, propane and propylene, butanes and butenes andthe like and are therefore useful for further transformations, at least the msaturated constituents, propane and the butanes. The remainder may be used as fuel or for other purposes. AA further by-prcduct, obtained in comparatively very small amount,'is a very low-boiling liquid (2S-80) which contains olee fines, dienes and the like and may be utilised accordingly. It is evident, therefore, that the liquid product obtained in my process, aside from a small, low-boiling, highly-unsaturated product, consists substantially of aromatics covering the entire range from benzene to polycyclic `compounds.

The process may be carried out in general terms as follows:

The vaporised feeding-stock or a mixture of the vapours with inert gases passes at a temperature ranging between 600 and 750, but preferably in the neighbourhood of 650 C. and at a pressure substantially near atmospheric pressure. over a. catalyst, consisting of a metal chosen from the group given below, or a mixture or alloy of v a plurality of such metals, either in compact form or deposited on a carrier, such as asbestos, pumice, bentonite and the like, which in itself has no catalytic effect on the hydrocarbon vapours under the specified conditions. The catalyst is placed in a horizontal or vertical steel tube, the material of which may or may not effect the same conversion as the catalyst, which will always have the predominant influence on the vapours, due to its much larger. active surface. The catalyst metals are chosen from the grouprof hydrogenation and dehydrogenation catalysts. thatfi'sfto and the permanent gases are collected and uti-l lised as desired. The products dissolved in the scrubbing liquid are removed by heating and together with the first liquid product subjected to a careful fractionation. It is also possible to isolate the reaction products by a process of fractional condensatlon. The aromatic products, so

isolated with great ease, are substantially pure crackingdescribed above."

A'rnc catalyst does not became'- appreciably 111-.

- xlictivated by carbonisation, which occurs in'similar-processes. known inthe conversion o t hydrocarbon .-oils.- If. however. a, marked decrease in activity has-taken place, thereactivation can .be

enectedlby successive treatment Awith oxygenor f oxygen containing gasesand hydrogen-or-'hydrofgen'containing gasesat appropriate temperay tures.. For -the second step in thurs-activation.

the gases may-conveniently be'.used ylrhichfre-'-v main after removal of the otherwisev -useiul constituents zirom the gaseous products; obtainedby theprocess oi catalytic, aromatising reforming The ease with'whichthe low-boilingl lviydrocurfV bon oils are aromatised. 1li-ascribed -to thecooperation vo'i two mechanisms:l (1) That described above, linvolving but'ylene, butadiene, acetylene, their -dlor poly' merisation, cyclo-isomerisation', or dehytirogena-v tive cyclisation of the polymerisation products, it they are not already hydroaromatic, and-{dehydrogenative aromatisation. -It is signincantf that the amount of oleilnes in the cracking gases4 destruc l tionof the molecules into low-moleculen` unsaturated compounds, such as ethylene, propylene,v

' il?? VIls Producti@ salumi-ange) ory the feedlngmk. atleast as of low-boilingaromaticsis u concerned.

. yI'hecc"considerations make it clear thatnot all .'thehydrocarbons present in-a gasoline are arowith equal ease. Substances likev meth- I yl-pentane or ethylbutane. inI general with. less six'carbon' atoms in a straight chain, can V;

`be aromatised by the nrst mechanism, and structuraliniluences will always play a part in y.th e speed{a1'1d ease oi aromatisation. a

*The invention consists ina process for the .Y conversion of aliphatic and `hiidroc'romatic min- .eral oilbodiesas herein set` out into a product 'comprisinga liquid-mixture of aromatic mbstances by subjectinga starting material as herein set forth to treatment by heat within 3 the temperature range of 60G-750. C. for the production'oi a mixture of substantially-pure aromaticv hydrocarbons, in contact with a hydrovgenatiou` and dehydrogenation catalyst.

' The invention also consists in processes for;v

fthe. conversion of'valiphatic land' hydroaromatic l .mineral-oil bodies-as herein set out into a procluct comprising a liquid mixture oi' aromatic subfollow. particulars of an example appliedv to the" f employment.. of* one of the. feeding-stocks men-` vstances substantiallyfree from vsulphur and .ni-

tragen compounds VVsubstantially as. herein de-` I .will nowgive particulars relating.. t0 the a ieedin'g-stock which have been employed in-certain examples ot `the present invention. Then tione'd, followed bya'nother sp'eclc example and then by tabulated references to othe'rfexamples more. details orwhichare shown in graphs as Eindicated later.

I nannte-Sr@ ron Anouxsrrsms samplesfoffrexss crude 21 n.11. I. 11cm: aisv10v l tillatesand their .extractaprepared'with'lOO/ is lower'when the speed ofl throughput isrelaf tively lowindicating that these olennes are- -fliquid sulphur dioxide,

used"v had` 'the following aromatics of substantially the same number ofl carbon'atoms. It can Well be imagined that' some of the products formed due tothe iirst mechanism by di-` and polymerisation vof the simple oleiines, are already present in the feeding stock. This mechanism becomes; obviously suppressed with the increasing molecular'v weight boiling gasolines 'can most easily be explained aromatised to a higher proportionand the characteristics:

Y sampled Sam lc B Sample C 'Sample D (gasoline (gasoline (extract 1 a0 c.) 10o-180 c 15o-wc.) 15o-250 0.)'

. 0.100 l 0.101 i 0.839; 0.855 v 4s 4a 50.15 -cao 9s c4 1oz 14a 111 104. 110 15s n 114 110.5 111. 5 115 n 111.5 18a 182 l n 125 188 n 132 1315 192.5 193v n 13s. 1 40 .20o 200. m 14s 149 v1:01' 201 m 154 151 210 215 n I, 167 227.5 226 9 q2 m 111 11s 239 236 F. B. P 10c 191 250 252 Bromine consumption min/g 8 111 8v 81 Solubility in dimethyl sulphate --percent.--.` 18 18 l 10l 20 formation of 1ow. boiling aromatics from higher GMPHS YReferring to the five accompanying graphs,

.l Graphs Ito IV have reference to gasoline and namely, in Graphs I and II,the chain curves c *applyto further cracked products.

Graph' V has 'reference' to heptane. `All the graphs show the relationship between temperal ture in degrees .centigradeand percentage: of dis- Ia is for the gasoline of boilingrange of 100- C.. sample A Jabove. Ila is for the gasoline extract of boiling range of 100-180' C., sample B above. IIIa is for the gasoline of boiling range of o-250 C., sample C above, and IVa is for the gasoline extract of boiling range of 150-250 C., sample D above.

The dash curves b are all for products obtained by cracking' at 650 C. The chain curves c are both for products obtained by cracking at 680 C.

In Graph V, the vertical full-line d applies to heptane and the dash-line e applies to the product cracked at 580 C.

EXAMPLE 1.-ARomArIs1NG Rxrolulmc or Sutri.: A

The catalyst consisting of a mixture of ne copper and iron turnings in the ratio of 5:1 and placed in a steel tube of 1 metre useful length and '7.5 cm. diameter, was activated, by successive oxidation with air at 400 C. and reduction with hydrogen at 250 C. and was then brought to a temperature of 650 C. Into the catalytic furnace, 1 kg. of the gasoline sample A was introduced at a rate of 126 g. per hour. The vapours of the reaction product were cooled with an eilicient water-jacketed condenser, giving 452.5 g. liquid product, and were then passed through a tower, ruled with 45o ce. spindie ou, which absorbed 83.5 g. liquid products. `'I'hese were rewere shown to be entirely aromatic by the usual methods. The effect of the process is demonstrated by Graphs Ia and Ib, which contain the boiling curves of the initial and the ilnal product.

Itk is possible to increase the amount of lowboiling aromatics, and of the very high-boiling aromatics. by re-cycling the fraction boiling at 14S-180 C. over the same catalyst.

The fraction 145180 was subjected to fractionation and was shown to contain the following principal constituents:

Bolling point, degrees Isopropyl-benzene 151 1.3.5-trimethyl-benzene (mesitylene)-- 162 Tert. butyl-benzene 168 1.2.4-trimethyl-benzene 170 Sec. butyl-benzene 174 1.2.3-trimethyl-benzene 179 Indene 181 Percent ot Substancel Boiling range total high Remarks fraction Tetra hydronaphthalene. m5210 C 5. 0 N aphthalene 210225 1l. 3 a-Methyl-naphthalenc- 240-247 4. 2 Picrate M. P. 140. a-Ethyl-naphthalene--. 252258 5.0 Picrate M. P. 116. Unidentiiied 265275- 4. 2 Picrate M. P. 122-123". l

o 195 in vacuo... 2. l Orange red picrate M. P. 134.

Anthracene 24W-210 in vacuo.. .s l2. 0 Unidentified substance.-. 345-347 in vacuc.. .i 7. 3 Dark-red Picrate M. P. 19o-108. Unidentified hydrocarbon. 350410 in vacuo... i 1.0 M. I. 288 Pitch Above 410 in vacuag 25 covered by heating the scrubbing liquidvto 200 C. and were combined with the first liquid.

The non-condensable gases amounted to 408 litres with a speciilc density of 1.149 g. per litre,

i. e. to 469.2 g. A sample of gas was taken before the scrubbing tower and showed the following composition:

Total amount Percent (by Percent (by formed "om volume) weight) l kg gasoline Grams Hydrogen 13. 90 l. l0 l5. 2 Meth 37. 85 23. 50 110. 2 Ethane 9. 1l. 30 53. 0 Ethylene 15. 40 16.75 78. 8 Propane l. 3. 15 14. 8 Propylene 10. 30 16. 80 78. 8 Butanes 0. 45 1. 00 4. 7 Butylenes (a and 3. 55 7. 70 38. 4 Iso-butylene 2. 6. 30 29. 5 Pentanes and pentenes. 2.05 5. 67 26. 6 Hexanes and hexenes. 2. 05 6. 75 3l. 0

The liquid reaction product was subjected to a careful fractionation, and the followin cuts were` g 6# creased; the constituents containing in their Heavy aromatics (boilingd above C.) 58.5

Tolerance :2%.

All the products. apart from the lowest one, 16 Ethyl-benzene fraction.

Substantial quantities of anthracene and especially chrysene may be isolated from the pitch.

The above list contains only the substances which have been isolated in substantial quantities; it does not indicate that thetabulated compounds are the only products formed.

According to a modification the charging stock was passed over a catalyst consisting of activated 0 copper at a temperature of 600 C. 'I'he total catalyst volume was 640 cc. of which 440 cc. were at the indicated temperature, while the temperature decreased by about 15 towards the ends of the furnace. As the rate of throughput was "I0 cc. per hour, the space veioclty was 0.16 litre per litre catalyst space per hour. 96% liquid product were recovered, while 4% of the charging stock were converted into gaseous products. 'I'he composition of the liquid product was, however, different from that of the starting material: 15% boiled up to a temperature of 145 C., 10% above so that '15% had retained the original boiling range. Fractionation of this part showed that the relative amount of trimethyl-benzenes had in- Per cent Below benzene 1.3 Benzene 1.5 Toluene 1.5 12.0

v 55% are mesitylene.

Similar experiment was carried out at 68o C.

190.v Fractionation of the low traction showed that it consisted of Per cent Head lfractionv 0.7 Benzene 3.5

Toluene 8.0

\ Ethyl-benzene 16.5 t

'I'he total amount ot low boiling aromatics is therefore higher than at son' c. and the increase in toluene is especially marked. In both cases,

however, the ethyl-benzeneiraction is the principal constituent.

In the fraction boiling between 'ur-190 c; From the highest traction naphthalene and temperature of 580 C. and at a rate of 200 s. per hour. I'he reaction product consisted of 732 g. liquid and 250 litres=225 g. gas. 'I'he product was not completely aromatised, although a fraction oi essentially pure benzene and toluene could be isolated, on fractionation. The incomplete aromatisation was indicated by the observav tion that only of the liquid were soluble in dimethyl sulphate, which does not dissolve n-heptane at all. It'was further observed that the liquid reaction product had a bromine consumpv tion oi' 227 mg. grams while the initial n-heptane anthracene were easily isolated; about of this fraction consisted of chrysene.

Oran Exmus nr Tissus Foxx The results o! other examples are summarised in the following table, and the eilect oi processing is demonstrated by the vaccompanying Graphs Nos. I to IV. All results are calculated on l kilogramme of starting material. Example 'A em`` ploys as a catalyst copper on pumice. Examples B, B1, C and D have copper-iron' catalysts.

' Feeding-stock 1 A B Bl O D 'rem ture --9 C-- cao y eso eso 65o cto Ca (l) v 0) 0) 150 154 143 167 203 488 l 398 1 480 l 356 1 282 1 l(l. 1) (1. 1) (1. l) 1. 18 (l. 1) 537 438 508 4Z) 310 450 544 402l 496 644 125 96 v 136 Z 324 Boiling below 80..do-..- 6.8 42.2 12.5 22.1 21.3 Benzene .-do'..-- 145.0 88.4 135.8 74.1 38.2 Toluene do-. 113. 1 151. 2 119. 6 81. 9 124. 0 X lene fraction-. do.. 42. l 1,26. 3 50. 5 69. 9 80. 8 Rber alkylbenzones -.do-... 18.0 40. 2 37.4 40. 3 46. 9

l Copper on pumice. l Copper-iron. v

.Composition of gas from working sample C at tsar-o. g

Percent by Percent by volume weigh Hydrogen 11.215v 0. 8 Methane 36. 90 22. 3 Ethano-- 12. l0 13. 7 Ethylene 15. 95 16. 9 Propane.-. 2.40 3. 9 Propylenell. 05 e 17. 5 Butanes. 0. l. 2 Butenes 3. 90 8. 2 Iso-butylene 2. 4. 6 Pentanes and pentenes 2. 30 6. l Hennes and hexenes 1.40 4. 5

Examen: ron Inraovnso 'rus Germ Ramto or N-Hsrrm 1 kg. n-heptane (3.1. iis-100) was miseri over the catalyst described in Example l at a Percent by Percent by volume weight 0 0 22. to 11, so' 21.00 20. 05 26.00 23. 3. l 4. 50 17.' 45 23. 30 0. 50 0. 90 5. 65 l0. 05 Iso-butylene- 1. 55 2. 76 40 Pentanes and peatones 1. 45 3. 25

Gllllul.'

was entirely saturated. The initial n-heptane is converted by the process described, into a liquid which has'the octane number 62.

The boiling range of the liquid as approximately shown in Graph V was as follows;

I. B. P C 40v Up to -per cent-- 3.0 80-85 l do 8.7 -90 -do k- 14.7 -95 do 33.1 100 do 28.2 Over.100 (mainly toluene) -do 6.0

The following table summarises the results of the analysis of the scrubbed gas from this example. which gas had a specic gravity of 1.1403 g./1itre (at 0 C. and '100 mm. pressure).

In this connection it may be mentioned that the low-boiling aromatic hydrocarbons as s uch or their mixtures are useful as constituents of high-grade fuels for internal combustion enveniently utilised for blending purposes, as its blending value has been determined to be 119.

The method gives a possibility to convert low- 1 boiling (10o-250 C.) gasolinas into aromatics.

either into single, well-dencd hydrocarbons or into a mixture of aromatic compounds with'unchanged or not-wholly varomatlsed (cycloparainnic, olennic') hydrocarbons. a

Variation of the conditions of reforming, both as to temperature and speed. permits to vary the ratio in whichthe single constituents of the v deriving from this reforming process itself or else lfrom any other source, or their solvent extracts or ramnates or mixtures.

terials or originating-from synthetic processes such as the Fischer-Tropisch process.

In particular, it is possible to use as charging stock directly the products of therr'nal` or cata-` lytic cracking of higherboiling petroleum cuts, without previous condensation or any additional treatment. In this case the utilisation of those parts of the reaction products, which are gaseous at ordinary temperature and atmospheric pressure, is preferably carried out by using jointly the gases formed in the cracking and the reforming process, respectively. One can vary the nature of the aromatics formed, at least to a certain extent: higher temperature, e. g.,- gives more benzene at the expense of ethylbenzene.

The compositions of fractionated products given above may have a tolerance 22%.

The following is a list summarising suitablev startingmaterials for the process according to the present invention, namely:

(a) Products of a cracking or reforming 3 process, carried out by thermal or catalytic methods with the crudes mentioned underv (l), their mixtures, solvent extracts, or raiilnates.

(b) Gasolines obtained by pclymerisa-A 35 tion processes from craekinggases, es-

pecially, those with 3 and/or 4 carbon atoms. their mixtures, solvent extracts or ramnates.

(c) Products obtained by hydrogenation 4 oi coal, high-boiling mineral oils, tars. f

creosotes and other carbonaceous materials, the hydrogenaticnbeingcarried out with or without catalyst, in one or more stages.

pounds (3) Synthetic materials: Gasolines, obtained by synthesis from non-hydrocarbon materials. especially those originating from the catalytic reaction between carbon monoxide and hydrogen (Fischer-Tropsch process).

In connection with gasolines, those most appropriate for treating according to the present,

20 ture Within the range of 600 to 750 C., at substantially atmospheric pressure and at a space velocity ranging from about 0.16 to 0.19` liter per liter of catalyst per hour, ,whereby a reaction product is obtained the liquid portion -of which 25 consists substantially completely of aromatic hydrocarbons aside from a small low-boiling, highly unsaturated fraction, and recovering said aromatic hydrocarbons.

2. In the manufacture of aromatic hydrocarbons from natural gasolines having boiling points within the range of about 100 to 250 C., the process which comprises passing such a gasoline in vapor form in contact with a nely-divided metal catalyst capable of catalyzing hydrogenation and dehydrcgenation reactions, at a temperature within the range of about 600 tc 750 C., at substantially atmospheric pressure and at a space velocity ranging from about 0.16 to 0.19 liter per literl of catalyst per hour, and condensing the resulting vapors, whereby aliquidreaction product is obtained which. aside from a small, low-boiling, highly-unsaturated fraction, consists substantially oi' aromatica covering the entire range from benzene to polycyclic com-