DE2324324A1 - NEW CATALYST, PROCESS FOR ITS MANUFACTURING AND ITS USE FOR THE CONVERSION OF ALKYLAROMATIC HYDROCARBONS - Google Patents

Description

Patent assessor 2324324 Hamburg, May 10th, 1973 Dr G. Schupfner T 73 023 (D 71 _f 9O7-PB)

GERMAN TEXACO AG. V / HH

2000 Hamburg 76 '

Sextuple gate 2

TEXACO DEVELOPMENT CORPORATION
135 East 42nd Street
New York, NY 10017
United States

New catalyst, process for its preparation and its
Used for the conversion of alky! Aromatic hydrocarbons. .

The invention relates to a new catalyst, a process for its preparation and the catalytic conversion of alkyl aromatic hydrocarbons using this catalyst. A particular embodiment of the invention is
directed to the catalytic disp-roportionierung of alkylaromatic hydrocarbons such as toluene, xylene, trimethylbenzenes, tetramethylbenzenes and pentamethylbenzenes.
In addition, the disproportionation of isomerization and
Be accompanied by transalkylation. In a further embodiment, the catalyst according to the invention is used for the selective catalytic DiGproportionation of alkylbenzenes, such as methylbenzene, cumene and n-propylbenzene, to give benzene and dialkylbenzenes . 309848/1121

The catalytic conversion of alkylbenzenes is so far with

a variety of catalysts have been carried out. The catalysts proposed for this purpose include H-mordenite,
containing a sulfided metal of Group VIII of the Periodic Table, and "particularly decationized or H-mordenites having a silica to alumina ratio as described in U.S. Patent 3,476,821. The process and catalytic compositions disclosed in this patent are disclosed bring numerous advantages, including that the catalysts have the ability to selectively _{convert toluene into benzene and xylenes, with virtually no n a} phthene being formed. If methyl-alkylbenzenes lead to dialkylbenzenes, the reaction is limited, or undesirable amounts of rialkylbenzenes are formed.

The invention has for its object to create a catalyst su that leads to a higher conversion of the alkylaromatic Hydrocarbons and an increase in the yields of the desired products; the catalyst is said to be better physical or have mechanical properties than the known. Furthermore, a method for producing this Catalyst are created.

The object is achieved by a catalyst that is characterized is in that the

a) H-mordenite with a SiO ^ / AlgO ^ molar ratio, the larger one is than about 10: 1,

309848/1121 " ³ -

b) a sulfided metal of Group VIII of the Periodic Systems

and

c) contains or consists of aluminum oxide.

According to the invention, this catalyst is produced by a process which is characterized in that

a) H-mordenite impregnated with a Group VIII metal will,

Td) this impregnated mordenite mixed with aluminum oxide hydrate
and

c) the resulting mixture is calcined at a temperature up to 593 ° C, so that the aluminum oxide hydrate is converted into eta- or gamma-aluminum oxide, and

d) the Group VIII metal is sulfided.

The invention also includes the use of this catalyst for the conversion of alkyl aromatic hydrocarbons * and the use is characterized in that the hydrocarbon is brought into contact with a sulfide compound and a catalyst composed according to the invention.

It has been found that the conversion of alkyl aromatic Hydrocarbons in the presence of the above-described catalyst according to the invention is significantly improved and that the catalyst compositions according to the invention

have better mechanical strengths, which extends their service life under the working conditions.

The process of converting alkyl aromatic hydrocarbons, which is described in more detail below, includes disproportionation of said hydrocarbons. as Further embodiments of the invention can also be the disproportionation of isomerization and / or transalkylation of the Be accompanied by hydrocarbon feed.

The alkyl aromatic hydrocarbons which according to the invention-n Procedures can be converted to close. Alkylbenzenes with one to five methyl groups. Particularly preferred alkylbenzenes are those containing 1 to 4 methyl groups contain; the feed can be any of the methylated aromatic hydrocarbons or mixtures thereof. Specific examples are toluene; o-, n- and p-xylene; Trimethylbenzenes, such as mesitylene, pseudocumene and hemimellites; Tetramethylbenzenes such as Durol, Isodurol and Prehnitolj and Pentamethylbenzenes together with mixtures of the aforementioned methylated aromatic hydrocarbons.

Another group of hydrocarbons which can be disproportionated by the process of the invention includes non-methyl alkylbenzenes of the formula below ,

309848/1121

in which R is an alkyl group with 2 to 16, preferably 2 to 4 C atoms means. Specific examples of these alkylbenzenes are: ethylbenzene, cumene, n-propylbenzene, tert.-butylbenzene, n-hexylbenzene, 2-n-hexylbenzene, isoocytylbenzene, n-decylbenzene, n-dodecylbenzene, 3-n-dodecylbenzene and n-hexadecylbenzene. Mixtures these alkylbenzenes can also be disproportionated? the preferred mixtures are those of compounds which have an equal number of carbon atoms in the alkyl group. As individually used alkylbenzenes, ethylbenzene, Cumene and tert-butylbeneol are preferred.

To convert the hydrocarbon by means of disproportionation the feed will be one or more alkyl aromatic Contains hydrocarbons, brought into contact with the catalyst according to the invention at a temperature in which the conversion of at least some of the alkyl aromatic hydrocarbons to aromatic products with a higher and in those with a lower number of carbon atoms.

In addition to the fact that hydrocarbons are subject to disproportionation, there is also the fact that hydrocarbons pass through the process of the invention can be isomerized; of isomerization are subject to alkylbenzenes with 2 to 4 methyl groups, o-, n- and p-xylene, trimethylbenzenes, such as mesitylene, pseudocumene and hemimellitol, and '^ etramethy! benzenes, such as durol, isodurol. and prehnitol, along with mixtures of the above

Alkylbenzenes. - 6 -

309848/1121

The disproportionation can also be carried out with the transalkylation be connected if the feedstock is a mixture of at least contains two alkylbenzenes with 1 to 5 methyl groups, with at least two alkylbenzenes in the mixture being one of each other have different numbers of methyl groups. For example, toluene and pentamethylbenzene can be converted into xylenes, trim- " ethylbenzenes and tetramethylbenzenes are transalkylated.

Disproportionation, isomerization and transalkylation can also take place simultaneously if the feed contains a mixture of at least two alkylbenzenes with 2 to 4 methyl groups, with at least two alkylbenzenes in the Mixture has a different number of methyl groups from one another. Such a conversion can be done, for example, when using a mixture of xylene such as o-xylene and 1,2,4,5-tetramethylbenzene be performed.

According to the invention, the composite catalyst, which is used for converting the hydrocarbons listed above, is prepared by converting an H-mordenite with a Si0 ₂ / Al ₂ O molar ratio above about 10: 1, but below about 100: 1, preferably from about 12: 1 to 80: 1. In a particularly preferred embodiment of the invention, an H-mordenite of an SiO ₂ / Al ₂ O molar ratio of about 25 1 to 50: 1 is used. H-mprdenites used as a component for the composite catalyst can be made from natural or commercially available synthetic sodium mordenites or commercially available

309848 / 112-1 - 7 -

H-mordenites with a Si0 _o / Alp0., - ratio of about TO: 1 can be produced.

The sodium form of mordenite is a component of the invention Catalyst ineffective »However, it can

can be converted into H-mordenite by exchanging the sodium ion in the mordenite for ammonium ions and then driving off the ammonia by heating or calcining. Alternatively, decationized or H-mordenite can be obtained by acid treatment of the sodium form. The H-mordenite (SiOp / AlpO, 10: 1), which is either produced as described above or is a commercial product, is then subjected to a sharp acid leaching in order to determine the molar ratio of SiO ₀ to Al ₀ O-, in the H- Increase mordenite to above about 10: 1. However, the crystalline structure of the mordenite must not be destroyed during acid leaching. Moreover, only a small improvement in the process is achieved when the SiOg / Al ₂ O, ratio of the mordenite is greater than about 100: 1. Consequently, as a practical limit, the acid treatment should be sufficiently severe to obtain a mordenite of an SiOg / AlGO ^ ratio of about 12: 1 to 80: 1, preferably about 25: 1 to 50: 1. A mineral acid, for example hydrochloric acid or sulfuric acid, is used to leach the H-mordenite with acid to selectively remove the aluminum without destroying the crystalline structure of the mordenite. Acid strengths of 1 to 8 η are suitable, and the acid leaching temperatures can be Range from room temperature to the boiling point of the acidic * kb ^ unA .. The acid treatment is

Best done when the mordenite is in powder form, not when it is tabletted. Following the acid treatment, the mordenite is washed free of acid anions with water and is in the form of small, soft aggregates, which generally have a particle size of about 0.5 to 10 mm .

The acid-leached Ή-mordenite is now suitable for impregnation with an aqueous solution of a salt of a group VIII metal. Group VIB metals can also be added to the mordenite and the impregnation solution of the group VIII salt can also contain soluble salts of Metals of group VIB contain, or an impregnation with a compound of a metal of group VIB can then be carried out separately. Group VIII metals, platinum, palladium, rhodium, ruthenium, nickel and cobalt are introduced in an amount sufficient to produce a finished catalyst composition containing from 0.2 to 10.0% by weight of a Group VIII metal to obtain. Nickel or cobalt are preferably used in amounts of 3.0 to 8.0% by weight. Platinum, palladium, rhodium and ruthenium are preferably present in an amount of about 0.2 to 2.0% by weight. The metal of group VIB, for example, tungsten, molybdenum or chromium, may also be added to the H-mordenite, in amounts of from about, 0.3 to 15 wt .- $ _f 0, based on the composite catalyst. After application of .the known impregnation, the impregnated high-SiOg-containing H-Mqrdenit is heated to a temperature of 38 to 15O ⁰ C, the impregnated particles to dry partially.

309848/1121 - ⁹ -

The improvements "in the conversion of the alkyl aromatics are achieved by mixing the metal-impregnated high-SiOk-containing H-mordenite with Al ₂ O, hydrate in such a way that the finished composite catalyst AlpO, as a component, in an amount of 10 to 50 wt. -. $, preferably contains from 15 to 30 wt -io practically is introduced the metal-impregnated mordenite in a freshly prepared deposition of hydrated alumina, such as alpha- or beta-AlPO, hydrate, and the components are passed through the colloid mill.. a uniform dispersion of mordenite in the Al "0. The mixing in the colloid mill has the result that the impregnated mordenite aggregates, some of which can have a diameter of 20 to 50 Å, into particles with an average diameter of about 0. It has been found that by impregnating the H-mordenite powder it is possible to achieve a more even distribution of the metal particles to achieve component than tablets formed by impregnation. The composition resulting from the mixing is then ^{dried at temperatures of about 55 to 66 0} C; higher or lower temperatures can also be used. The composition is then ground and sieved, for example through a 0.42 mm (-40 mesh) sieve. It will be

around
Sufficient water is added to obtain a readily extrudable mixture and the composition is brought into the shape desired for the intended use. The particles can be ground, for example in an ore mill, to obtain a finely divided catalytic mass, or shaped into beads

309848/1121. - 10 -

but it is preferred to extrude the composition.

Räch molding, the composition is dried and calcined at temperatures up to 593 ⁰ C. The composition can be dried at room temperature or at temperatures of about 150 ^° C. for several hours. It can 'also with; Room temperature and thereafter the temperature started to be raised to about 15O ⁰ C. Thereafter, the composition at temperatures of about 260-593 ⁰ C, preferably in a stream caleiniert dry gas and at maximum temperatures 454-538 C. When the composition is calcined, the alumina hydrate changes to gamma- or eta-alumina, depending on whether the starting hydrate was alpha- or beta-AlpO. When the calcination is completed, the converted AlpO is converted into a solid binder. Tablets or spheres produced by this method have a bursting strength of 4.54 to 18.1 kg, while catalysts that do not contain AlpO ^ are soft and have significantly lower bursting strengths.

The metal component, the Group VIII metal, of the calcined composition is then converted to the sulfide and maintained in that state while the catalyst is in use. The metal component can be prepared by bringing into contact mi.t as hydrogen sulfide in a carrier gas such as hydrogen at a temperature of 204-427 ⁰ C sulfided advertising the. According to another method, the catalyst can be

3 09848/1121 - 11 -

working temperature and then with the liquid, with a sulfur-containing compound such as carbon disulfide or methyl disulfide, enriched feedstock.

Since the sulfided catalyst metal can be reduced during use, particularly when the alkyl aromatic conversion is carried out in the presence of hydrogen, the catalyst can be maintained in a sulfided state by introducing small amounts of sulfur compounds into the reaction vessel. This can be done by adding hydrogen sulfide to the hydrogen stream entering the reactor, or by incorporating compounds such as carbon disulfide or methyl disulfide, which rapidly decompose to hydrogen sulfide in the presence of hydrogen under the conditions prevailing in the reactor. These additives should be sufficient to provide a molar ratio of hydrogen sulfide to hydrogen in the gas phase of 3 x ΙΟ ^"4 *" to be maintained to 1 χ 10 ~ ² over the catalyst. For example, molar ratios of hydrogen sulfide to hydrogen of 7 × 10 to 5 × 10 are used, the higher ratios of HpS: H ₂ generally being used at higher reaction temperatures. It has been found that this low concentration of sulfide gives the desired result without contaminating the conversion products.

Although hydrogen is widely used in the known catalytic conversion processes, its use is in the

309848/1121 - 12 -

Process according to the invention is not critical. ^{However, it is} recommended because it extends the life of the catalytic converter. In general, the preferred operating conditions for the conversion of alkyl aromatic hydrocarbon when it is a methyl substituted benzene are as follows: Space velocities in the range of about 0.1 to 15 volumes of liquid per volume of catalyst per hour (LHSV), preferably -0.5 to 8 LHSV; Temperatures in the range from about 204 to 400 ^° C., preferably 232 to 343 ^° C., pressures in the range from 7.03 to 140.6 atmospheres, preferably in the range from 56.2 to 84.4 atmospheres; and if hydrogen is used, hydrogen concentrations of 16.9 to 2535 lim ^ / m ⁵ (100 to 15,000 scf / bbl), preferably 845 to 1690 "Sn? / m * (5000 to 10,000 scf / bbl). The reaction is most conveniently carried out over a fixed bed catalyst with the feed passing through the catalyst bed in a downward direction.

When the catalysts for the disproportionation of alkylbenzenes in which the alkyl groups of 2 to 16 have C-atoms is used, the working conditions are substantially the same except that for ethylbenzene and cumene with advantage temperatures from 177 to 343 ⁰ C, preferably from 232 to 316 ⁰ C, and for compounds with butyl and higher alkyl groups from 204 to 288 ⁰ C can be used.

As the catalysts age, their activity slowly decreases. The catalyst can be kept at almost its original activity or at periodic intervals to close to its

3 09 848/1121 - 13 -

original activity can be brought back by the working temperature is increased. Finally, the catalyst can be regenerated by oxidation, which is a controlled one Combustion of the impurities on the surface of the catalyst structure with air or an inert mixture Includes gases with air or oxygen.

The invention described above provides useful advantages in two respects. First, the composite catalyst has significantly greater mechanical properties than de-aluminized mordenites which contain a Group VIII metal sulfided. The improved mechanical strength is attributed to the presence of eta- or gamma-alumina in the composition. Second, and this is completely surprising, the activity of the composite catalyst containing the alumina is much greater. Such a result was not to be expected, since alumina is actually an inert material for the disproportionation of alkylbenzenes. In G _e g _ENAA tz to what was expected, namely that the catalytic activity would the sulfided Group VIII metal containing de-aluminized mordenite by dilution with Al ₂ O sink, it has been found that higher conversions, i.e. converted alkylbenzene, result in the presence of the composite catalyst.

It has been found that when working under the conditions and with a catalyst, as described above, an admixture

309848/1121 -H-

-H-

material from methylated aromatics is selectively converted into products that are largely free of ethylated aromatics, Gr- and C "-naphthenes and light hydrocracked, below 65.6

C are boiling products. For example, disproportionate ! Toluene to benzene and isomeric xylenes, yielding a product that is largely free of ethylbenzene, making it an attractive one Source for the production and recovery of p-xylene from Cg- " Aromatic fractions is created. The disproportionation also leads of o-xylene to a product with a low content of alkylated aromatic isomers, so that the concentration is relatively high in trimethylbenzenes, and the Extraction of mesitylene, in particular by distillation, is due to the practical lack of ethyl toluene, such as o-ethyl toluene, relieved. Another advantage of the absence of ethylbenzene in the xylene fraction is the possibility , the recovery of p-xylene by cryogenic crystallization more effective. The disproportionation of xylene and more highly methylated benzenes leads to isomerization the Cg-, CQ- and C.Q-methylbenzenes about their thermodynamic Equilibrium distribution,

After the disproportionation and isomerization of o-xylene, pseudocumene and other polymethylbenzenes, the relative amounts of the dimethyl, trimethyl and tetramethylbenzene isora are almost in agreement with the amounts that thermodynamic considerations suggest. The relative amounts of dimethyl, trimethyl and tetraraethylbenzenes sB _r in the Cg, Cq or. GQ fractions from thermodynamics

309848/1121 - 15 -

In terms of equilibrium, the following are to be expected ^{at 227 and 327 0 G:}

Temperature, ⁰ C 227 327

- $ in the C _D fraction

20.6 21.9 55.2 '54.1 24.2 24.0 6.0 7.7 67.1 67.8 26.9 24.5 13.1 15.2 51.3 50.5 35.6 34.3 "

1,2-dimethyl benzene 1,3-dimethylbenzene 1,4-dimethylbenzene - $ in the C ^ fraction

1,2,3-trimethylbenzene 1,2,4-trimethylbenzene 1,3,5-trimethylbenzene - '/ in the C _1Q fraction

1,2,3,4-tetramethylbenzene 1,2,3,5-tetramethylbenzene 1,2,4,5-tetramethylbenzene

As can be seen from the examples given below, the relative amounts of dimethylbenzenes and trimethylbenzenes from the isomerization and disproportionation of xylene are in good agreement with these thermodynamic values. When pseudocumene '(1,2,4-trimethylbenzene) is disproportionated, the amount of prehnitol (1,2,3,4-tetramethylbenzene) is somewhat smaller relative to other tetramethylbenzenes and the amount of durene (1,2,4,5 -Tetramethylbenzene) slightly larger than the amounts predicted according to the chemical equilibrium. The formation of a slightly larger amount of durol with respect to prehnitol than expected according to the thermodynamic equilibrium is a desirable result, since durol is a more valuable material and its recovery is _{favored by higher contents in the C ir} . Fraction.

^ιυ - 16 -

309848/1121

■ »■ 16 -

It has also been found that ethylbenzene disproportionates to form m-, p- and o-diethylbenzenes and none other material is produced that boils in the vicinity of these compounds. The amounts of p-, m- and o-isomers are approximately those as they are to be expected according to the thermodynamic equilibrium, and the conditions are as they are with other types of catalysts can be obtained.

Small amounts of triethylbenzenes are also formed during the disproportionation of ethylbenzene. However, unlike the results obtained with zeolite Y catalysts, when the ratio of 1,3,5- to 1,2,4-triethylbenzene corresponds to the thermodynamic ratio of 2: 1 when using the composite acidic mordenite -Catalyst with high SiO _? / AlpO, molar ratio according to the invention

^ of

the ratio of 1,3,5- to 1,2,4-triethylbenzor ** well below 2 found.

When cumene disproportionates, the diisopropylbenzenes and benzene are the dominant products and some triisopropylbenzene is also formed. The diisopropylbenzenes are formed in a ratio that is the same as that with other catalysts Is found. But when using the invention

high acidic mordenite catalyst with the ^ SiOp / AlpO, molar ratio the ratio of 1,3,5- to 1,2,4-triisopropylbenzene formed significantly below that expected for triisopropylbenzenes Value.

- 17 309848/1121

The total amounts of trialkylbenzenes (1,3,5- and 1,2,4-Trialkylbenzenes) lower than those with other catalysts at the same non-methyl-alkylbenzene degree of disproportionation can be obtained. The disproportionation is primarily restricted to the formation of benzene and dialkylbenzene, and secondary disproportionation of the dialkylbenzenes is suppressed. This suggests for the 'compound Catalysts according to the invention act as shape-selective catalysts.

The disproportionated and isomerized aromatic hydrocarbons «, which are obtained by the process according to the invention are used as solvents or as starting materials for the manufacture of numerous .industrial chemicals and products. For example, o-xylene is used ale Starting material for the production of phthalic anhydride and phthalate plasticizers, while m-xylene is important for the production of isophthalic acid. p-xylene is used in the manufacture of Terephthalic acid or terephthalic acid ester used, which are used in particular for the production of polyester fibers. The benzene produced in the process is used as a solvent and as a starting product for the synthesis of styrene, phenol, Nitrobenzene and cyclohexane suitable, which in turn for the production of products such as synthetic rubber, detergents and insecticides. Other aromatic hydrocarbons, like the trimethylbenzenes, pseudocumene and mesitylene are used to produce trimellitic anhydride, from which non-volatile plasticizers are made,

309848/1121 - 18 -

or trimesic acid, which are used to produce crosslinked polymers is suitable used. Tetramethylbenzenes, such as Durol, are used to divide pyromellitic acid dianhydride, which is required for the synthesis of polymers with resistance to higher temperatures.

Diethylbenzenes can by means of chromatographic adsorption " separated and then to diviny! benzene, a polymer precursor, becoming dehydrated. Likewise, p-diisopropylbenzene can be added p-Diisopropenylbenzene, also a monomer, is dehydrated will. The o-, m- and p-diisopropylbenzenes are also valuable Starting products for the production of catechol, resorcinol and hydroquinone by adding the diisopropylbenzene to the corresponding Dihydroperoxide is oxidized, which is split into the dihydroxybenzene and acetone.

In order to make the invention even more clear, a few examples will now be given.

example 1

2000 gr. Of a commercially available sodium mordenite powder with an average particle size of 10 to 30 microns, a composition of 6.86 wt .- ^ Ma ₂ O, 10.2 wt .- ^ and 68.2 wt .- # SiO ₂ and a molar ratio of SiO of 11.4 / 1 were -unterworfen with 4 liters of 6 η HCl at a temperature of 54 to 60 ⁰ C for 24 hours to an acid treatment. The acid was decanted off, the pests washed three times with 4 liters of hot water and three times with 4 liters of cold water, like that

3098487 1 12 1. · " ¹⁹ "

that a product was obtained which was made up of 0.95 wt. $ Na _? 0, 6.9 wt .- $ Al ₂ O ₅ and 86.1 parts by weight of SiO ₂ was 56 and a molar ratio of Si0 ₂ / Al ₂ 0, of 21.2 / 1 was obtained. The acid leaching was repeated, the product was washed chloride-free, dried at about 150 ⁰ C and at a temperature of ca, calcined ⁰ 538 G in a dry air stream. The finished acid leached mordenite consisted of 0.09 wt .- ^ Na ₂ O, 3.74 wt .- ^ Al ₂ O, and 88.2 wt .- ^ SiO ₂ and had a molar ratio of SiO ₂ / O ₅ of 40 /1 .

410 gr. This acid-treated mordenite were contained with 250 ml of cobalt nitrate solution containing 125 gr. Co (NO ^) ₂ · 6H ₃ O, impregnated and the impregnated powder was then for 16 hours at 54 to 60 ⁰ C dried.

368 grams of Al ₂ (SO.) ^. 18H ₂ O were dissolved in 3 liters of distilled water. To this, 300 ml of concentrated ammonium hydroxide was added to precipitate aluminum hydroxide. The precipitate was collected by filtration and washed three times with distilled water. The cobalt-impregnated acid-treated mordenite was mixed with the wet alumina hydrate precipitate and passed through a mill to effect homogeneous mixing. After the mixture at a temperature from 54 to 6O ⁰ C for 16 hours in part had been dried, it was extruded mm spheres having a diameter of 1.587; the balls were then 16 hours at room temperature, 8 hours

dried at 54 to 60 C and 16 hours at 150 C and

finally calcined in dry air at 538 ^° C. for 2 hours.

309848/1121

The calcined catalyst spheres were at 37o C ⁰ sulfided 4 hours hydrogen sulfide. The sulfided catalyst obtained consisted of 4.4% by weight of cobalt and 15% by weight of gamma-aluminum oxide, the remainder being H-mordenite with a SiOp / AlpO-j molar ratio of 40/1. The composite catalyst, in the Chatillon Crush Strength Tester, had an average burst strength of 9.07 kg.

A series of tests were conducted using a toluene feed consisting of toluene of $ 99.8 and CS _{2 of} $ 0.2. The feed was introduced into the disproportionation reactors containing 100 cubic centimeters of the catalyst prepared as described above under the operating conditions summarized in Table I.

In the temperature range from 260 to 316 ⁰ C, the maximum conversion of toluene by disproportionation is theoretically about 58 $. From Table I it can be seen that is approached to the chemical equilibrium at 288 ⁰ C and a space velocity of 2 LHSV to about 87 $, at the same time maintaining a high selectivity for benzene and polymethylbenzene. For example, the Cg aromatic fraction consists almost entirely of dimethylbenzenes (xylenes) with less than 0.4 $ ethylbenzene. This Cg fraction is then an excellent material for separating off xylene, since it is not necessary to separate off ethylbenzene by fractionation before the p-xyl oil recovery can be started. The xylene concentrations in the co-aromatic fraction are with each other in the thermodynamic

309848/1121 " ²¹ "

Table I.

attempt

Temperature, C

LHSV

Pressure, atü

Molar ratio H ₂ / KW io S in the feed

Product analysis _t wt .- ^ cracked below Cg

C, - ^ C "-, C" -naphthenes Benzene toluene ethylbenzene p-xylene m ~ xylene o-xylene p-ethyltolnol m- and o-ethyltoluene Mesitylene Pseudocumene Hemiraellitol Ethylxylenes Durol Isodurol Prehnitol heavier than C-q

2
268

5.3
56.2

0.2

0.05

9.77

78.23

8.66

2.26
0.07

0.26
0.62
0.07

0.01

302

4.9 56.2

5
0.2

0.08 17.77 59.82

15.27

4.13 0.22

0.72 1.62 0.21 0.03 0.05 0.04 0.02 0.02

Equilibrium, and the same is true of the trim thy! Benzole the C ^ fraction.

At even higher flow rates of the toluene over the catalyst at temperatures from 269 to 302 ⁰ C , very good conversions are still found

309848/1121 - 22 -

Example 2

2000 g of the commercially available Na mordenite powder, which was also used in Example 1, was acid-treated four times under the conditions specified in Example 1. After the final acid leaching of the mordenite was 0.02 wt -.? O Na ₂ O, 2.54 wt .- $ ^A lp ° ^and 9 ° 3 ^»6 & ew .- $ SiO ₂ and had a molar ratio of Si0 ₂ / Al ₂ 0, from 6O / 1. 4OO gr. Of the acid-treated mordenite described above were mixed with 200 ml of a nickel nitrate solution containing 107 gr. Ni (NO ₃ J ₂ · 6H ₃ O, impregnated and the impregnated powder dried for 16 hours at 54 to 60 ⁰ C,

817 g of Al ₂ (SO ₄ ), 18H ₂ O were dissolved in 3 liters of distilled water, and 400 ml of concentrated ammonium hydroxide was added to precipitate aluminum hydroxide. The precipitate was collected by filtration and washed three times with distilled water. Half of the alumina gel obtained was used for the preparation of the catalyst.

720 g of the nickel-impregnated, acid-leached mordenite were mixed with 1455 g of moist aluminum oxide hydrate gel and mixed together homogeneously in a mill. After partial drying of the mixtures at 54 to 60 ⁰ C for 16 hours, the mixture was mm.gemahlen to a particle size of less than 0.42 and sieved (ground and sieved to -40 mesh). Sufficient water was added to obtain a readily extrudable mixture, and this material was then extruded into spheres 1.587 mm in diameter. The balls

309848/1121 - 23 -

- • 23 -

v / ere then 16 hours at room temperature, for 8 hours at 54 to 6O ⁰ C and 16 hours at 150 ⁰ C dried. .Danach the beads were ealciniert in dry air, starting "was temperature of 538 ⁰ C at a temperature of 26O ⁰ C and ending at a temperature of 538 ⁰ C, the temperature was raised to 55 ⁰ C per hour at the end of the Catalyst calcined in dry air for 2 hours.

The catalyst was then dried at 371 ⁰ C for 4 hours with HpS sulfides: diert and then cooled in a dry nitrogen stream. The sulfided catalyst consisted of 4.6% by weight of nickel, 5.5% by weight of sulfur and 15% by weight of gamma-aluminum oxide, the best was H-mordenite with a SiOp / AlpO, molar ratio of 60/1. The material had an average burst strength of 6.35 kg as determined in the Chatillon Crush Strength Tester.

Example 3

460 g of a commercially available H-mordenite powder, consisting of 8.9 wt a solution containing 125 gr. Co (NO ^) ₂ .6H ₂ O, impregnated. The material was dried at 54 to 60 ^° C. for 16 hours.

368 grams of Al ₂ (SO.), 18H ₂ O were dissolved in 3 liters of distilled water. To this, 300 ml of concentrated ammonium hydroxide was added to precipitate aluminum hydroxide. The precipitate was collected by filtration and three times with distilled water

washed. ₂ y _

309848/1121

669 gr. Of the cobalt-impregnated H-mordenite were found with 971 gr. moist aluminum oxide hydrate gels mixed and mixed homogeneously in a colloid mill. After partial drying of the

long

Mixtures at 54 to 60 C for 16 hours, it was ground to a particle size below 0.42 mm (ground and sieved to -40 mesh). Sufficient water was added so that good extrudability was ensured, and the material was extruded into spheres with a diameter of 1.587 mm. The spheres were then dried and calcined in the same manner as described in Example 2. The catalyst consisted of 4.7 wt .- $ ₄ cobalt and 15 wt .- ^ gamma-alumina, the rest was H-mordenite a siop / AlPO ^ molar ratio of 16/1 and had an average burst strength of 18.1 kg . The catalyst was sulphided in the same way as described in Example 2 and had the following calculated composition: 5.0% by weight of cobalt, 2.7% by weight of sulfur and 15.0% by weight of fo gamma aluminum oxide, the Remainder H-mordenite; it had about the same burst strength as the unsulfided material.

Example 4 (comparative example)

2000 g. Of commercially available sodium mordenite in the form of spheres with a diameter of 1.587 mm, consisting of 7.2 wt .- # Na ₂ O, 12.5 _{wt .- # Al 3} O ₃ and 75.0 wt .- ^ SiO ₂ and one

KolveiMltnisses of Si0 ₉ / _o Al 0 ₇ of 10/1 were mixed with 4 liters ο η KCl for 24 hours at a temperature from 54 to 60 ° C acid- "behandslt. You acid ~ in? Ae irnci decanted. The solids dreiisal sit 5 Liters of hot water and three times with δ liter of kaita: n water gowaschan »The acid leaching was three weeks

303848/1121 -25-

Repeated times and the product washed free of chloride, ^{dried at about 150 °} C. and calcined ^{at 538 °} C. in dry air. The mordenite obtained, leached with acid was 0.07 wt AU3 ^c / ₃ Na ₃ O, 2.3 wt .- # Al ₃ O ₃ and 88.3 wt .- ^ siop, and had a SiC ^ / A ^ O ^ molar ratio of 65/1. 423 g of the acid-treated mordenite spheres were then impregnated with 200 ml of a cobalt nitrate solution containing 105 g of Co (NO,) ~ 6HoO. After 2 hours of drying on a steam plate and 16 hours drying at 15O ⁰ C, the spheres were calcined in dry air, starting one hour at 26O ⁰ C, after which the temperature was raised to 55 C per hour until a temperature of 5'38 C was reached. The spheres were then calcined in dry air at this temperature for 2 hours.

The calcined spheres were at 37o C ⁰ sulfided 4 hours HpS. The resulting catalyst consisted of 5.5 wt. -Fo cobalt, 3 »4 wt .- ^ sulfur and the rest of an H-mordenite MoI verhältnisöes of SiCg / Al ^ O., Of 65/1. The catalyst had an average burst strength of 1.8 kg.

Example 5 (comparative example)

340 g of aluminum oxide balls with a diameter of 1.587 mm were impregnated with 200 ml of a cobalt nitrate solution containing 90 g of Co (NO,) p.6HpO. The spheres were dried, calcined and sulfided, as described in Example 4. The material obtained had a calculated composition of 4.7 wt .- $ cobalt, 2.5 wt -.% Sulfur and the balance alumina, and an average burst strength

309848/1121 " ²⁶ "

of 5.76 kg. Such a catalyst has practically no activity, alky! aromatic hydrocarbons of the type according to the invention can be treated »to disproportionate.

Example 6 ■

4000 gr, · of commercially available sodium mordenite powder, consisting of 6.86 wt .- $ Ha ₂ O, 10.2 wt .-% AlgO, and 68.2 wt .- $ SiOp, and a molar ratio SiO ₂ ZAl ₂ O, from 11.4 / 1, was acid-treated with 8 liters of 6 η HCl for 24 hours at a temperature of 54 to 60 ^{0 G.} The acid was decanted and the solids washed three times with 4 liters of hot water and three times with 4 liters of cold water. The acid leaching was repeated a second time and the product was washed free of chloride ions, ^{dried at about 150 °} C. and in dry air

C calcined. The finished acid-treated mordenite consisted of 0.31% by weight of Na ₂ O, 4.53% by weight of Al ₂ O ₅ and 90.9% by weight of SiO ₂ and had a SiOg / AlgO ^ - Molar ratio of 34/1.

1323 gr. Of the acid-treated mordenite described above were reacted with 600 ml of a cobalt nitrate solution containing 375 gr. Co (NO) ₂ .6H ₂ O, impregnated and the impregnated powder 16 hours at a temperature from 54 to 6O ⁰ C dried

1470 g, Al ₂ (SO.), 18H ₂ O was dissolved in 12 liters of distilled water and 1000 ml of concentrated ammonium hydroxide was added to precipitate aluminum hydroxide. The precipitate was through. Filtration recovered and washed three times with distilled water

309848/1121 ~ ^2Ί ~

washed.

The cobalt-impregnated säuregelaugte mordenite was mixed with the moist alumina gel and _f by homogeneously mixing to achieve, passed through a colloid mill. After the mixture had partially dried for 16 hours at 54 to 60 ^° C., it was ground to a particle size below 0.42 mm. Sufficient water was then added to make the mixture readily extrudable and the material then extruded into spheres 1.587 mm in diameter. The balls were 16 hours at room temperature, 8 hours at 54 to 60 ⁰ C and 16 hours! 150 ⁰ C dried. Thereafter, the spheres were calcined in dry air, beginning at 260 ⁰ C ,, then the temperature per hour was increased to 55 C until a final temperature of 538 ⁰ C is reached wurv - "\ at this temperature, the catalyst was calcined for 2 hours ,

The calcined catalyst was then sulfided with hydrogen sulfide at 370 ° C. for 4 hours and then cooled in dry nitrogen. The sulfided catalyst consisted of 3.5 wt .- $ cobalt, 7.5 wt ~ fo sulfur, 15.0 wt -.. ⁰ Jo alumina, the rest was H-mordenite a Si0 ₂ / AlPO, molar ratio of 34 / 1 The material had an average burst strength of 39.7 kg., Determined in the * ChatilIon Crvsh Strength Tester '.

Example T

The catalysts obtained according to Examples 4 Ms 6 were numerically rated for their ability to be »alkylaromatic

309843/112 1

To disproportionate hydrocarbons, to determine. In this example, toluene was chosen as the feedstock Results are given in Table II below. The feed used in the experiments reported in Table II consisted of $ 99.8 of toluene and $ 0.2 of carbon disulfide; it was introduced into the disproportionation reactors which contained 100 cm of the respective catalyst.

Table II 5 6th Catalyst / example 4th 291 289 Temperature, ⁰ C 289 3.3 3.0 IHS? 2.9 56.2 56.2 Pressure, atü 56.2 4.7 5.3 Molar ratio H ₂ / KW 5.2 Product analysis, weight - #. 0.1 0.2 Non-aromatics 0.2 0.1. 18.7 benzene 10.0 99.8 56.6 toluene - 77.0 _ .. 21.5 Cg aromatics 11.8 - 3.0 Cq aromatics 0.9

From Table II it can be seen that the catalyst 5, consisting of cobalt sulfide on alumina, was practically nonexistent

led

Toluene conversion ^ and was considered inactive. The introduction of alumina as a component of a catalyst made from an acid leached mordenite, which is a metal of group VIIIB carries, resulted in a catalyst (catalyst 6), which was significantly better than an acid-leached mordenite that carried a Group VIII metal (catalyst 4). The conversion of toluene under practically the same conditions of temperature, pressure, space?; E8 speed and

309848/1121 "· -29-

Hydrogen / hydrocarbon molar ratio was using the catalyst 6 almost twice as large (45,4.5 $) _w ^ _e in .The use of the catalyst 4 ($ 23).

Another material, which is not shown in Table II, and which consisted of 15 wt .- ^ aluminum oxide and the remainder of H-mordenite with a Si0 ₂ / Al ₂ 0 ₃ molar ratio of 40/1, led to a at 283 ⁰ G low toluene conversion (about $ 15) »The deposition of carbon on this material resulted in rapid deactivation.

No transition metal hydrogenation component when on the catalyst is present, it is quickly deactivated due to coke deposition. The addition of 0.5 to 10 wt .- #, preferably 3 to 8 wt. $ Nickel or cobalt, or from 0.2 to 2.0 Weight-5 & platinum, palladium, rhodium or ruthenium reduce the deactivation rate of the catalyst. Catalysts, containing about 5 wt. $ cobalt, which is in the sulfided state, worked with little over 300 hours Loss of conversion rate, whereas the same catalyst without metal was practically inactivated within 24 hours as a result of carbon deposits.

Example 8

A catalyst composed of 5 wt. $ Cobalt, 5.5 wt. $ Sulfur, 15% by weight aluminum oxide and the remainder H-mordenite one Molar ratio of 40 / I, in the form of 3.175 mm spheres, was used to convert o-xylene and pseudocumene,

309848/1121 - 30 -

- 30 -
Table III 2324324 Input material o-xylene Pseudocumene Temperature, ⁰ C 262 263 Pressure, atü 56.2 56.2 IHSV 2 1.5 Mo! Ratio Hg / KW 5.8 8.2 Product analysis,% by weight cracked light paraffins 0.14 0.27 " Naphthenes 0.10 0.24 benzene 1.80 0.12 toluene 17.40 2.17 Ethylbenzene 0.01 p-xylene 12.84 - 4.03 m-xylene 31.65 10.10 o-xylene 14.11 3.40 p-Ä thy11οluo1 0.01 0.02 m-ethyltoluene 0.05 0.06 o-ethyltoluene <0.01 ^ l 0.01 1,3,5-trimethyrbenzene 4.86 15.22 1,2,4-trimethylbenzene 13.60 36.89 1,2,3-trimethylbenzene 1.51 4.42 Ethylxylenes 0.07 0.22 1,2,4,5-tetramethylbenzene 0.73 8.51 1,2,3,5-tetramethylbenzene 1.00 11.80 1,2,3,4-tetramethylbenzene 0.14 1.95 Ethyltrime thy! Benzene - 0.11 Pentaniethylbenzene 0.42

each feedstock being 0.2% sulfur as methyl disulfide contained. The results are summarized in Table III.

Table III shows that the catalyst has high activity and selectivity for the isomerization and disproportionation of_

309848/1121.

Possesses polymethylbenzenes. o-xylene is, the chemical Coming close to equilibrium, isomerized to over $ 95 and to about 70 $ of the theoretical fourth to benzene, toluene, trimethylbenzenes and tetramethylbenzenes are disproportionated. The ratio of the trimethylbenzenes formed from 1,2,3 to 1,2,4 to 1,3,5 isomers is 7.5: 68.2: 24. This ratio is actually the same as thermodynamics predicts. When o-xylene is isomerized, practically no ethylbenzene is formed educated. When o-xylene is disproportionated, the trimethylbenzenes are selectively formed, with only a small one Amount of ethyl toluene is produced. The total amount of the three ethyltoluene isomers in the CQ aromatic fraction is below $ 0.35. The trimethylbenzenes, practically not contaminated from the ethyltoluene isomers, can therefore be separated off.

Pseudocumene (1,2,4-trimethylbenzenes) is also isomerized to the other trimethylbenzenes mesitylene and hemimellitol and disproportionated to toluene, xylenes and tetramethylbenzenes. The aromatic fraction with one more carbon atom, namely the C., -.- fraction, as a feedstock is again essentially free of ethyl aromatics, such as ethyl xylenes. Consequently, Durol can easily be obtained from the C. ₀ aromatic fraction by crystallization. The ratio of the three tetramethylbenzenes formed during the disproportionation, namely the 1,2,3 »4 isomer to the 1,2,3,5 isomer to the 1,2,4,5 isomer, is 8", 8: 53 »O : 38.2. Although close to thermodynamic equilibrium, the amount of prehnitol (1,2,3 _f 4-tetramethylbenzene) is somewhat smaller and the amount of durol (1,2,4,5-tetramethylbenzene)

309848/1121 -32-

.slightly larger than expected from the chemical equilibrium leaves.

Example 9

A catalyst consisting of 3.5 wt .- ^ cobalt, 9.5 wt .- $ sulfur and 15.0 wt - $> alumina and the rest of H-mordenite a SiC ^ / algo-z mole ratio of 34 /. 1 was used in the form of spheres with a diameter of 1.587 mm for the disproportionation of ethylbenzene and cumene. The conditions and results are shown in Table IV. 71 g of catalyst were used in each of the experiments. In addition, in experiments A and B, an ethylbenzene was used as the feedstock which contained 2.3 ml of methyl disulfide per liter of ethylbenzene. In Runs C and D, a cumene was used as a feed containing 2.4 ml of methyl disulfide per liter of cumene,

As can be seen from Table IV, half of the introduced Ethylbenzene disproportionated to benzene and diethylbenzenes, with very little triethylbenzene or other By-products arise. The total amount of Triäthylbenzoie is less than a third of the total amount from the degree the primary disproportionation of ethylbenzene is to be expected. In addition, the amount of 1,3 »5-triethylbenzene that is formed is smaller than the amount of 1,2,4-triethylbenzene, -obwohl the Thermodynamics says that the amount of 1,3,5 isomers doubles is as high as the amount of 1,2,4-isomers. The diethylbenzenes are formed in the proportion as it is from thermodynamics

309848/1121 - 33 -

Tabel IV C. D. attempt A. B. 274 299 3 temperature, ⁰ C 274 300 56.2 56.2 Pressure, atü 56.2 56.2 2 2 LHSV 2.6 2 3.6 3.5 Molar ratio H ₂ / KW 3.1 3.2 Product analysis, weight »- $ 0.7 1.9 Non-aromatics 0.6 2.0 17.0 21.3 benzene 18.0 20.0 0.1 0.1 toluene 0.2 0.8 0.4 0.5 Ethylbenzene 49.9 48.1 42.6 39.9 Cumene - - - - m- and p-ethyltoluene 0.3 0.8 - - o-ethyltoluene track 0.1 - m-diethylbenzene 18.3 15.8 - - p-diethylbenzene 8.4 7.2 - - o-diethy! benzene 2.0 1.7 ' - - 1,3,5-triethybenzene 0.8 1.7 - - 1,2,4-triethybenzene 1.3 1.1 4.5 7.2 n-propylbenzene - - 17.0 11.8 m-diisopropylbenzene - - 0.2 0.2 o-diisopropylbenzene - - 12.2 10.2 p-diisopropylbenzene - - 0.9 1.6 1,2,4-triisopropylbenzene - - 0.1 0.2 1,3,5-triisopropylbenzene - - 4.4 5.2 not identified 0.1 0.4

is to be expected from here.

A similar result is obtained when cumene disproportionates will. The triisopropylbenzene formation is relative to that what the cumoid disproportionation would lead one to expect is suppressed. . Likewise, the 1,3,5-1! Bopropylbenzene formation is relative to the 1,2,4-Triieopropylbenzene formation suppressed.

309848/1121

- 34 -

From the above it can be seen that the Forin-selective Character of the composite acid-treated Mordenlt catalyst according to the invention for the disproportionation of ethylbenzene and cumene is of great advantage. It will be dialkylbenzenes which are more desirable than the Trialky! benzenes, and suppressed the catalyst of the invention the formation of the triethylbenzenes and the ü? r ii s ο propy! benzenes.

- 35 -309848/1121

Claims (7)

T 73 023 D. Claims η \ catalyst, characterized in that.er a) H-mordenite of a SiOp / ΑΙρΟ, -Μο! ratio, the larger one ale is about 10: 1, b) a sulfided metal of Group VIII deB Periodic Systems (PS), and c) contains or consists of aluminum oxide. 2. Catalyst according to claim 1, characterized in that that the Group VIII metal in an amount of 0.2 to 10.0 wt .- $ based on the finished Catalyst, present » 3 * catalyst according to claim 1 or 2, characterized in that that the Group VIII metal is nickel or cobalt and in an amount from 3.0 to 8.0 , based on the finished catalyst, is present. 4 »Catalyst according to one of claims 1 or 2, characterized in that the metal of group VIII Is platinum, palladium, rhodium or ruthenium and in an amount of 0.2 to 2.0% by weight, based on the finished catalyst, is present. - 36 - 309848/1121 5 # catalyst according to one of the preceding claims, d a .by characterized that the aluminum. oxide is eta- or gamma-Al ^ O-, and in an amount of 10 up to 50%, based on the finished catalyst. 6. Catalyst according to one of the preceding claims, d a you r. ch- marked that the Al ^ O, in an amount of 15 to 30 wt .- ^, based on the finished Catalyst, is present. 7. Catalyst according to one of the preceding claims, characterized in that it is 3.0 to 15.0 Group VIB sulfided metal by weight of PS contains. 8. Catalyst according to claim 7, characterized in that the metal from group VIB tungsten, Is molybdenum or chromium. 9. Catalyst according to one of the preceding claims, characterized in that the molar ratio of SiO ₂ to Al ₂ O _{5 is} about 12: 1 to 80: 1. 10. Catalyst according to claim 9, characterized in that • draws that the SiOp / AlpO, molar ratio is about 25: 1 to 50: 1. - 37 -309848/1121 11. A method for producing a catalyst according to any one of claims 1 to 10, characterized in that that a) H-mordenite impregnated with a metal from group VIII of PS, "b) the impregnated mordenite mixed with aluminum oxide hydrate, c) the resulting mixture is calcined to a temperature of 595 ⁰ C, so that the Alurainiumoxid hydrate in eta- or gamma-ALPO, converts, and d) the Group VIII metal is sulfided, 12. The method according to claim 11, characterized in that that the H-mordenite is additionally impregnated with a metal from group VIB before b). 13. The method according to any one of claims 11 or 12, characterized in that the calcining is carried out at a temperature between 454 and 538 ^° C. 14. A method according to any one of claims 11 to 13 characterized dadur oh "that the sulfiding is carried out at a temperature of 204-427 ⁰ C. 15. The method according to any one of claims 11 to 14 »thereby characterized in that the sulphiding is carried out with hydrogen sulphide. - 38 - 309848/1121 . - 38 - 16 »Use of the catalyst according to one of claims 1 to 10 for conversion - disproportionation and optionally Isomerization and transalkylation - of alkyl aromatic hydrocarbons, being the hydrocarbons substances with a sulfide compound and the catalyst in Be brought into contact. 17. Use according to claim 16, characterized in that that the hydrocarbons are alkylbenzenes with 1 to 5 methyl groups. 18. Use according to claim 16, characterized in that the hydrocarbons are alkylbenzenes with 1 to 4 methyl groups. 19. Use according to one of claims 16 to 18, d a characterized in that the hydrocarbons one or a mixture of the compounds toluene, xylene, dimethylbenzene, tetramethylbenzene and pentamethylbenzene is, 20. Use according to one of claims 16 to 19 »characterized in that the conversion takes place at a temperature of 204 to 400 ⁰ C, preferably 232 to 343 ° C, with a liquid volume space velocity per volume of catalyst per hour (LHSV) from 0.1 to 15, preferably 0.5 to 8 IHSV, and a pressure from 7.03 to 309848/1121 - 39 - 141 a-fcü, preferably 56.2 to 84.4 atü will, 21, use according to one of claims 16 to 20, characterized in that the hydrocarbons fall under the following formula: in which R is an alkyl group with 2 to 16 carbon atoms « 22, use according to claim 21, characterized in that that R is an alkyl group with 2 to 4 carbon atoms and the alkyl aromatic hydrocarbon preferably ethylbenzene, cumene, n-propylbenzene, tert «- Butylbenzene or a mixture of n-propyl and isopropylbenzene is. 23. Use according to claim 21 or 22, characterized ge kennze ichne t that the conversion at a temperature of 177 ⁰ C to 343 ° C at a space velocity of 0.1 to 15 LHSV and a pressure from 7.03 to 141 atm made will, 24 »Use according to claim 23, characterized in that that the alkyl aromatic hydrocarbon Ethylbenzene or cumene is and the conversion takes place 232 to 316 ° C is carried out. - 40 - 309848/1121, 25. "Use according to one of claims 21 to 24, characterized in that R is an alkyl group with 4 "to 16 carbon atoms and the conversion is at made at a temperature of 204 to 288 C wiz'd « 26. Use according to one of claims 16 to 25, characterized in that the contact is made in the presence of hydrogen. 27. Verv / endung according to claim 26, characterized in that the hydrogen is made in an amount of 16.9 to 2535 Nm ⁵ / m ³ , preferably 845 to 16900 Nm ³ / m ^{3 of} the hydrocarbon used. 28. Use according to claim 27, characterized in that the sulfide compound in an amount is used, which ensures that the molar ratio of hydrogen sulfide in the gas phase over the catalyst to hydrogen 3 × 10 to 1 χ 10 ", preferably 7x10 ~ ⁴ to 5x10 "'. 309848/1121