CS222744B1 - Catalyser for dealcylazing the alcylbenzene - Google Patents

Abstract

The invention relates to a catalyst for de-alkylating alkylbenzenes by reacting water vapor with a hydrocarbon feedstock consisting of of at least one alkylbenzene, optionally of mixtures containing at least one alkylbenzene. The catalyst contains alumina as a carrier on which they are deposited in a particular the weight concentration of the active ingredient chosen of precious metals VIII. periodic groups system of elements, at least one metal from the group consisting of lithium, sodium, potassium, rubidium, cesium, beryllium, magnesium, calcium, strontium, barium and uranium and at least one metal from the group consisting of copper, silver and gold. In addition, the catalyst contains rhenium at a concentration of 0.05 to 2.0 why. The catalyst is regenerated with hydrogen at room temperature temperature of 100 to 500 ° C. For his extraordinary the selectivity of the catalyst can be used outside others in the dealkylation of aromatic mixtures and non-aromatic hydrocarbons.

Description

The present invention relates to a catalyst for the de-alkylation of alkylbenzenes by reacting water vapor with a hydrocarbon feedstock comprising at least one alkylbenzene or a mixture comprising at least one alkylbenzene. The catalyst comprises alumina as a support onto which a noble metal active ingredient selected from noble metals VIII is deposited at a certain concentration by weight. at least one metal of the group consisting of lithium, sodium, potassium, rubidium, cesium, beryllium, magnesium, calcium, strontium, barium and uranium; and at least one metal of the group comprising copper, silver and gold. In addition, the catalyst contains rhenium in a weight concentration of 0.05 to 2.0 Why. The catalyst is regenerated with hydrogen at a temperature of 100-500 ° C. Due to its extraordinary selectivity, the catalyst can be used, inter alia, in dealkylation of aromatic and non-aromatic hydrocarbon mixtures.

The invention relates to the petrochemical industry, in particular to catalysts for the alkylation of alkylbenzenes by reaction with steam.

The invention may be particularly needed for the de-alkylation of hydrocarbon feedstocks consisting of at least alkylbenzenes, optionally a mixture of at least one alkylbenzene and non-aromatic hydrocarbons, by reaction with water vapor to produce benzene and its low molecular weight homologues.

Alkylaromatlckých dealkylation reactions of hydrocarbons with steam is carried out in the presence of catalysts at temperatures in the range 400 to 600 ^C C and pressures ranging from 0.1 to 2.0 MPa in the supply of hydrocarbonaceous feedstock at a space velocity of 0.1 to 10 h ^-1, preferably 1 to 5 h ¹ and at a water: hydrocarbon molar ratio in the range of 1: 1 to 20: 1, preferably in the range of 2: 1 to 10: 1.

The process for the alkylation is particularly used for the production of benzene. Commonly used as the hydrocarbon feedstock for dealkylation are toluene, C8 hydrocarbons of the benzene series, for example ethylbenzene or xylenes, C9 hydrocarbons of the benzene series, for example trimethylbenzenes or ethyltoluenes, as well as higher molecular weight benzene series hydrocarbons and finally aromatic hydrocarbons with condensed ring systems. such as naphthalene, phenatren, anthracene, and homologues thereof. Mostly, however, either toluene or the aromatic fractions of benzene rich in toluene and other hydrocarbons of the benzene series are used.

The dealkylation reaction takes place, for example, with toluene according to the following equations:

C6H5CH3 + H2O-> CeH5 + CO + 2 Hz

C6H5CH3 + 2 HzO → CeHe + CO2 + 3 H2

At the same time as dealkylation, a series of side reactions of the benzene ring occur with the interaction of the hydrocarbonaceous feedstock and benzene with steam or hydrogen, resulting in a reduction in benzene yield. The course of side reactions also reduces the selectivity of dealkylation.

Various catalysts are known for dealkylating alkylbenzenes with the aid of water vapor, but which have insufficient activity or stability or low selectivity.

From the Soviet author's certificate no. 198 310 are for example known dealkylation catalysts which contain rhodium deposited on alumina or alumosilicate. The selectivity of such a catalyst in dealkylation of toluene is only 90 mole percent and the conversion of toluene is 53%,

The selectivity of catalysts with the addition of other metals is somewhat higher. The selectivity of catalysts comprising a platinum group metal, iron oxide, chromium oxide and an alkali metal on a support (U.S. Pat.

436 433), rises to 94 to 95 mole percent.

French Patent Specification No. 2 146 210 also discloses a dealkylation catalyst consisting of alumina of 0.05 to 2% by weight of precious metals VIII. groups of the periodic system of elements (rhodium, platinum, rhutenium, palladium, iridium, osmium J and 0.05 to 2% by weight of a metal selected from the side I of the periodic system (copper, silver, gold). Alkaline earth metals, as well as uranium in an amount of 0.01 to 5% by weight, a catalyst comprising rhodium, copper and alkali and alkaline earth metals being preferred, the selectivity of such catalyst being 96 to 97 mole percent with a toluene conversion of 60%. Insufficient stability of the catalyst means that due to the reduction in catalyst activity over a period of time, this loss must be compensated for by an equally rapid increase in reactor temperature, but this leads to a shorter catalyst lifetime. so that the toluene conversion remained at 60% con Stable, the operating temperature should be raised from 441 ° C to 459 ° C, ie 18 ° C during this period. It is known that, in terms of economy, the lifetime of noble metal catalysts must be greater than one year. As the activity is reduced more rapidly, it is necessary to recycle the catalyst in order to guarantee the necessary lifetime of the catalyst, which also reduces the efficiency of the process, since the catalyst is not in operation during catalyst recovery. A further disadvantage of this known catalyst is that when using a feedstock which also contains non-aromatic hydrocarbons in addition to alkylaromatic hydrocarbons, the yield of the final product is also reduced. For example, when 10 mole% of n-heptane is added to toluene, the temperature in operation must be increased by 20-25 ° C to obtain the same benzene yield.

Thus, the present invention solves the object of finding a suitable choice of components and their ratio to the composition of the catalyst for the alkylation of alkylbenzenes by reaction with steam, which at the same time has a sufficiently high selectivity and stability and thereby allows to increase the yield of the desired product.

According to the present invention, the above-mentioned drawbacks have been overcome by the discovery of a catalyst for the alkylation of alkylaromatic hydrocarbons consisting of at least alkylbenzene or a mixture of at least one alkylbenzene and non-aromatic hydrocarbons by reaction with water vapor consisting of alumina as carrier to which active components are deposited. which are selected from precious metals VIII. at least one metal selected from the group consisting of lithium, sodium, potassium, rubidium, cesium, beryllium, magnesium, calcium, strontium, barium and uranium, as well as groups of the Periodic Table of the Elements (platinum, palladium222744 dium, rhodium, ruthenium, yridium, osmium); and at least one metal selected from the group consisting of copper, silver, and gold, and which according to the invention additionally contains rhenium at the following ratio of components. in percent by weight:

one or more precious metals of VIII. groups of the periodic system of elements (platinum, palladium, rhodium, Iridium, ruthenium, osmium)

0.1 to 20%;

at least one metal selected from the group consisting of lithium, sodium, potassium, rubidium, cesium, beryllium, magnesium, calcium, strontium, barium and uranium

0.03 to 5.0%;

at least one metal selected from the group consisting of copper, silver and gold

0.05 to 2.0%;

rhenium

0.05 to 2.0%;

aluminum oxide residue.

The addition of rhenium to the catalyst leads to a strong increase in its stability and selectivity. The increase in selectivity is particularly evident when using a hydrocarbonaceous feedstock which, in addition to alkylaromatic hydrocarbons, contains non-aromatic hydrocarbons. The rhenium content of the catalyst is 0.05 to 2% by weight. According to the experimental data, the selectivity of the catalyst with increasing rhenium content in the rhodium-copper-containing catalyst increases, but at a rhenium content greater than 2% by weight, however, the activity of the catalyst in the dealkylation reaction decreases. With a rhenium content in the catalyst of less than 0.05% by weight, the effect of rhenium is negligible. It can be found that in the presence of only copper or only rhenium in the catalyst itself, its selectivity also increases, but with the addition of both components, an additive effect is not achieved but a strongly synergistic effect of increasing selectivity. Of particular importance is the fact that the stability of the rhodium-containing catalyst is also substantially increased in this case.

According to a variant of the process according to the invention, the catalyst contains, as effective compensation, rhodium in an amount of only 0.1 to 1.0% by weight as the active component, since of the platinum group metals rhodium exhibits maximum activity in dealkylation reactions.

When the rhodium content is below 0.0% by weight6, the catalyst activity decreases strongly. The use of catalysts containing more than 1.0% by weight of rhodium is economically unsuitable due to the high cost of rhodium.

According to a further variant of the process according to the invention, it is recommended that the catalyst contains rhodium as an active component in admixture with another noble metal VIII. % of the Periodic Table of the Elements in an amount of 0.1 to 2.0% by weight. The selectivity of the rhodium-containing catalyst alone is 85 to 90 mole percent and is insufficient for industrial use in the dealkylation process. Catalysts containing other platinum group metals, such as platinum or palladium, satisfy their high selectivity (up to 100 mole percent) but are insufficiently active and poorly stable. It is therefore expedient to use catalysts which, in addition to rhodium, also contain other platinum group metals.

Preferably, the catalyst comprises copper in an amount of 0.05 to 1.0% by weight.

The metals of the first side group of the Periodic Table of the Elements, and in particular copper itself, are promoters (synergistic enhancers) that serve to increase the activity and selectivity of dealkylation reactions. At a copper content of less than 0.05% by weight, an increase in the selectivity of the rhodium catalyst is hardly detectable and when the copper content is greater than 1% by weight, the stability of the catalyst decreases.

The following content of catalyst components in% by weight is preferred:

rhodium 0.1 to 1.0% copper 0.05 to 1.0% rhenium 0.1 to 0.9% at least one metal selected from the group consisting of lithium, sodium, potassium, rubidium, cesium, beryllium, magnesium, calcium, strontium , barium and uranium 0.03 to 3.0%

It has been found in experiments that this ratio of catalyst components guarantees its high selectivity in dealkylation, and that the presence of alkali metal, alkaline earth metal and / or uranium makes it possible to reduce coke formation, causing an increase in catalyst stability.

The hydrocarbon feedstock for the process may be pure alkylbenzene, optionally a mixture of aromatic and non-aromatic (saturated, naphenic) hydrocarbons, which is produced as a product of catalytic reformation and pyrolysis. Under the conditions of dealkylation by reaction with steam, non-aromatic hydrocarbons react primarily to form gaseous products (hydrogen, carbon monoxide, carbon dioxide), which allows the final product to be deactivated. In addition, naphthenic and saturated hydrocarbons are partially converted to aromatic hydrocarbons under reaction conditions. In this method of alkylation, the nitrogenous aromatic compounds present in the starting material, such as pyridine, and its derivatives are not disturbed, since these decompose to form nitrogen and / or ammonia.

At the same time, it is recommended that the feedstock contains not more than 1 ppm, preferably not more than 0.5 ppm of sulfur.

The dealkylation process produces both full dealkylation (benzene) and partial dealkylation products such as toluene or xylene. Typically, benzene and partially dealkylated products are formed simultaneously. For example, benzene, toluene and xylenes are simultaneously obtained from trimethylbenzenes. These by-products can be recycled to obtain the dealkylated product.

Toluene and mixtures containing larger amounts of toluene are particularly recommended.

The catalyst support of the present invention is selected from eithacubic, gamma-cubic, gamma-tetragonal, xicubic, kappa-orthorhombic, theta-monoclinic, delta-orthorhombic and rho-amorphous alumina. This alumina has a surface area in the range of 50 to 400 m ² / g, a surface area in the range of 80 to 350 m ² / g is recommended. Ball shaped shapes are recommended as shaped alumina.

The catalyst of the present invention can be prepared by any known methods. The active components are applied to the alumina in the form of aqueous solutions or other solutions of active compound compounds by saturation. Each component may be applied separately to the support while drying, calcining or regenerating the catalyst prior to each additional saturation with a different solution. However, saturation with a solution of several components can also be carried out at the same time. The following compounds can be used to prepare the catalyst: noble metals VIII. groups of the periodic system, copper, silver, gold and other elements in the form of halides, nitrates, acetates or carbonates, alkali metals in the form of formates, citrates, chloric acid and their ammonium salts, mixtures of at least one of said metals with oxalic acid and oxalates, with citric acid and citrates, or other polyacids, acids, alcohols, aminoalcohols. Rhenium is often used in the form of rhenistic acid (aqueous solution of rhenium oxide) or ammonium perrhenate.

Before use, the catalyst is regenerated with hydrogen at temperatures ranging from 100 to 500 ^° C.

The catalyst of the present invention is used under known conditions of the dealkylation process at temperatures in the range of 400 to 600 ° C, at a pressure in the range of 0.1 to 2.0 MPa, a volumetric velocity of hydrocarbon feedstock in the range of 0.5 to 5 h ^-1 and a molar ratio of water to hydrocarbon feedstock in the range of 1: 1 to 20: 1, preferably 2: 1 to 10: 1.

The advantages of the catalyst according to the invention are that, with high selectivity, its stability is two to three times higher than that of the known catalysts, which allows a corresponding extension of its service life. In addition, due to its extremely high selectivity (100 mole percent), the catalyst of the present invention allows use in dealkylation of aromatic and non-aromatic hydrocarbon mixtures. Such a high selectivity is due to the fact that a large proportion of saturated hydrocarbons are dehydrocyclised to form benzene under process conditions using a catalyst. With the use of known catalysts, this effect is virtually eliminated and, moreover, the dealkylation reaction slows down even when switching to the raw material.

When using the catalyst of the present invention, the yields of the end product are practically unchanged when switching to the mixed feed. Said efficiency when using the catalyst of the present invention in dealkylalkyl alkylbenzenes mixed with non-aromatic hydrocarbons is increasingly important as the reformed and pyrolysed aromatic gasoline fractions contain such mixtures. These fractions are substantially cheaper as a raw material for dealkylation compared to toluene or other aromatic hydrocarbons.

The following are typical examples that illustrate certain aspects of the present invention, with the particularities and advantages of the present invention being disclosed. Example 1 (comparative)

Ethyl cubic alumina in the form of spheres having a diameter in the range of 1.8 to 2.5 mm is used as the catalyst support. The specific surface area of the carrier is 200 m ² / g, the pore volume is 60 ml / 100 g. To prevent cracking during saturation, alumina is continually moistened with water vapor at 80 ° C.

The support is saturated with 2000 ml of solution A containing 6.0 g of rhodium in the form of rhodiumtrlchlorohydrate and 55 mm of hydrochloric acid (dao = 1.19). Rhodium is adsorbed in the grains of the carrier material with uniform distribution. The solution was decanted off and the catalyst was dried at 50 ° C, 100 ° C and 200 ° C for 3 hours. Then the catalyst is saturated with 600 ml of solution B which it contains

9.4 g of copper chloride dihydrate, 8.5 ml of hydrochloric acid (d20 = 1.19) and 12.2 g of potassium nitrate.

Finally, the catalyst is dried for 2 hours at 50 ° C, for 3 hours at 100 ° C and for 5 hours at 200 ° C. Then, the catalyst is regenerated by flowing a stream of hydrogen at 550 ° C for 3 hours at a volume rate of 300 volumes of hydrogen per catalyst volume per hour.

The regenerated catalyst is then saturated with solution C containing 40 g of potassium nitrate in 550 ml of water, dried as described above and calcined with hot air at 400 DEG C. for 3 hours. The finished catalyst consists of 0.58% rhodium, 0.33% copper,

1.5% by weight of potassium, 0.3% by weight of calcium and the rest of the alumina.

This catalyst is finally regenerated at 500 ° C for 2 hours with hydrogen and tested in dealkylation of toluene to benzene.

The molar content of the feedstock was 97% toluene and 3% xylene with 0.2 ppm sulfur contaminants. Unreacted xylenes and toluene are recycled to the reactor.

The test conditions are as follows: pressure 0.7 MPa, feed rate 2 h ^-1 , water: hydrocarbon feed 5: 1 molar ratio. The test temperature is chosen to guarantee 70% conversion.

The percent conversion is calculated using the following equation:

Conversion in% 100 χ f ^toluene + xylenes) in. ~ (tol. + xyl. output (toluene + xylenes) in _pU (number of compounds are given in moles) selectivity of benzene formation in molar percent is calculated according to the following equation:

selectivity = 100 x formed benzene (mol) reacted tol. and xyl. (mol)

The benzene yield in mole percent is calculated according to the following equation:

,, conversion x selectivity

The degree of cleavage of the benzene ring is equal to the difference between the conversion (70%) and the yield of benzene.

The relative activity of the catalysts is determined by the temperature at which 70% conversion of the feedstock is achieved after 100 test hours. The stability of the catalyst is determined from the temperature difference required to maintain the feedstock conversion at 70% after 1000 hours of operation.

Using a catalyst of the above composition, the temperature that guarantees 70% conversion after 100 hours of operation [thiool 445 ° C, after 1100 hours of operation (luoo) is 471 ° C. Stability is therefore due to a temperature increase of 26 ° C, the selectivity of benzene formation is 94.5 mole percent (after 100 hours), the benzene yield is 66.15 mole percent, and the degree of benzene ring cleavage is 3.85%.

In the same manner, all the catalysts listed in the following Examples 2 to 12 were tested. The results are shown in Tables 1 and 2.

Example 2

The catalyst is prepared in the same manner as described in Example 1, but instead of Solution B described in Example 1, 600 ml of a solution containing 8.4 g of ammonium perrhenate, 9.4 g of copper chloride dihydrate, 12.5 ml of hydrochloric acid and 12 ml are used. , 5 g calcium nitrate.

The finished catalyst has the following composition: rhodium 0.58% by weight, rhenium

0.57% by weight, copper 0.33% by weight, calcium 0.3% by weight and potassium

1.5% by weight. This catalyst was tested by the method described in Example 1.

With the same raw material as in Example 1, the following results were obtained: thioo = 460 ° C;

mp = 472 ° C;

stability = 12 ° C;

benzene formation selectivity = 97.1 mole percent;

benzene yield 68 mol%; degree of benzene ring cleavage 2%. Example 3 (comparative)

The catalyst is prepared in the same manner as described in Example 1, but instead of solution B described in Example 1, 600 ml of a solution of 8.4 g of ammonium perrhenate, 1 R, 5 ml of hydrochloric acid and 12.5 g of calcium nitrate are used. The catalyst thus prepared has the following composition: rhodium 0.58 why. %, rhenium 0.57%, potassium 1.5% and calcium 0.3%. This catalyst was tested with the same raw material and under the same conditions as described in Example 1. The tests showed the following values:

mp = 475 ° C;

mp = 496 ° C;

stability = 21 ° C;

benzene formation selectivity = 95.8 mol percent;

benzene yield 67.05 mol%; degree of benzene ring cleavage = 2.95%.

The results of the tests according to Examples 1 to 3 are shown in Table 1. The data show that a catalyst containing both rhenium and copper has better results than a catalyst containing these components separately. In addition to the high selectivity (97.1 mol%), the catalyst prepared according to Example 2 also exhibits a slight degree of benzene ring cleavage at 70 why. (2% vs. 3 and 3.8% respectively), as well as substantially higher stability (12 ° C vs. 21 ° C and 26 ° C with other catalysts, respectively).

Thus, the simultaneous presence of copper and rhenium in the catalyst causes a synergistic effect on stability and selectivity.

Example 4

The carrier used is alumina of gamma-tetragonal and gamma-cubic modifications in the form of extrudates with a diameter of 1.2 mm and a length of 4 to 7 mm, with a specific surface of 250 m ² / g and a pore volume of 55 ml / 100 g. The mixture was saturated with 1600 ml of a solution containing 5.6 g of rhodium in the form of rhodium trichloride hydrate and 60 ml of hydrochloric acid (J = 1.19). After five hours of saturation, excess liquid from the saturated support is removed and the support is dried for 3 hours at 50 ° C, 100 ° C, 150 ° C and 200 ° C. The carrier is then saturated with 520 ml of aqueous solution B containing 8.4 g of ammonium perrhenate, 9.5 g of copper chloride dihydrate, 14 ml of hydrochloric acid, 30 g of citric acid monohydrate and 43 g of uranyl nitrate hexahydrate. The treated carrier is further treated as described above, calcined in air for 4 hours at 350 ° C and then regenerated in a mixture of hydrogen (10 volumes) and nitrogen (90 volumes) at 580 ° C for 5 hours . The regenerated catalyst is saturated with 5.2 g of potassium nitrate and 42.2 g of magnesium nitrate in 500 ml of water, dried as described above, and then annealed for one hour in air at 300 and 400 ° C. The produced catalyst has the following composition:

rhodium 0.55% by weight;

rhenium 0.56% by weight;

copper 0.33% by weight;

magnesium 0.4% by weight;

potassium 0,2% by weight and

2.0% by weight of uranium.

The catalyst prepared in this way was tested under the conditions described in Example 1.

The catalyst test results are as follows:

mp = 455 ° C;

mp 100 = 466 ° C;

stability = 11 ° C;

benzene formation selectivity = 97.7 mol percent;

benzene yield = 68.4 mol%; degree of benzene ring cleavage = 1.6%.

The results of the experiment are shown in Table 2 below.

Example 5

The catalyst is prepared as described in Example 4, but instead of 520 ml of solution B, 520 ml of solution Bi is used which contains 8.4 g of ammonium perrhenate, 9.5 g of copper chloride dihydrate, 38.1 g of barium nitrate, 12 g of malic acid, 8 ml of hydrochloric acid, 53 g of magnesium nitrate. The produced catalyst has the following composition:

rhodium 0.53% by weight;

rhenium 0.55% by weight;

copper 0.32% by weight;

magnesium 0.5% by weight and barium 2% by weight.

The catalyst was tested under the same conditions and with the same raw material as in Example 1, giving the following results:

mp = 460 ° C;

mp = 472 ° C;

stability = 12 ° C;

benzene formation selectivity = 97.6 mol percent;

benzene yield = 68.3 mol%; degree of benzene ring cleavage = 1.7%.

The results of the experiment are shown in Table 2 below.

Example 6

The carrier used in this example is the same as the carrier used in Examples 1 to 3, i.e. in the form of spheres. 1000 g of this carrier are saturated with 2000 ml of an aqueous solution containing 5.8 g of rhodium in the form of rhodium trichloride hydrate, 50 ml of hydrochloric acid (dzo = 1.19) and 11.2 g of ammonium perrhenate. After six hours of saturation, the excess solution is filtered off with suction and the catalyst is dried for 5 hours at 50 ° C, for 3 hours at 100 ° C and also for 5 hours at 200 ° C. The catalyst is then regenerated with a mixture of hydrogen and nitrogen (50 volumes of hydrogen and 50 volumes of nitrogen) in a flow rate of 400 volumes of regeneration mixture per catalyst volume per hour for one hour at 200 ° C, then 400 ° C for 2 hours and finally for 3 hours at 560 ° C. After cooling, the product is saturated with 590 ml of a solution containing 214 g of magnesium nitrate hydrate, 20 g of strontium nitrate, 9.4 g of copper chloride hydrate and 19 g of citric acid monohydrate. The catalyst is then dried as described above and calcined for 2 hours at 400 ° C. The finished catalyst has the following composition:

rhodium 0.58% by weight;

rhenium 0.51% by weight;

copper 0.33% by weight;

strionium 0.8% by weight;

magnesium 2.2% by weight.

The catalyst was tested under conditions and with the same feedstock as described in Example 1.

The following values were obtained during the experiment:

mp = 455 ° C;

mp = 468 ° C;

stability = 13 ° C;

benzene formation selectivity = 97.4 mol percent;

benzene yield = 68.2 mol%; degree of benzene ring cleavage = 1.8%.

The results of the experiment are shown in Table 2 below.

Example 7

The carrier used in this case is the same as the one described in Examples 1-3. 1000 g of this carrier are saturated with 2200 ml of solution A containing 6.3 g of rhodium in the form of rhodium trichloride wire and 57 ml of hydrochloric acid. After five hours, the solution is decanted and the catalyst is dried for 5 hours at 80 ° C, then for 3 hours at 220 ° C and finally again saturated with stirring 590 ml of solution B containing 7.45 g of ammonium perrhenate 4.3 g of copper nitrate hexahydrate, 32.5 g of uranyl nitrate hexahydrate and 40 g of citric acid monohydrate. After 3 hours regeneration in air as well as drying for 3 hours at 50 ° C, 120 ° C and 240 ° C, the catalyst is calcined for 2 hours at 320 ° C and then regenerated in a stream of hydrogen at 500 ° C. ° C for 6 hours. The catalyst thus obtained contains 0.6% rhodium, 0.51% rhenium, 0.15% copper and 1.5% uranium.

The catalyst was subjected to the same tests with the same feedstock as in Example 1. The experiment gave the following results:

mp = 452 ° C;

mp = 463 ° C;

stability = 11 ° C;

benzene ring selectivity = 97.2 mol%;

benzene yield = 68.05 mol%; degree of benzene ring cleavage = 1.95%.

The values obtained are shown in Table 2 below.

Example 8

The carrier used is commercially available alumina with a gamma-cubic configuration in the form of spheres. The diameter of the balls is

1.8 to 2.5 mm, the specific surface of the support is 190 m ² / g and the pore volume is 70 ml / 100 g. 1000 g of this support are saturated with 2500 ml of a solution containing 5.1 g of rhodium in the form of rhodium trichloride hydrate and 52 ml of hydrochloric acid . After stirring for 5 hours, the solution is decanted and the catalyst is dried at 80 ° C for 5 hours, then at 150 ° C for 2 hours and finally at 240 ° C for 3 hours. The product thus prepared and dried is saturated with 2000 ml of a solution containing 1.6 g of platinum in the form of hexachloroplatinic acid,

10.8 g of ammonium perrhenate and 25 ml of hydrochloric acid. After six hours the excess solution is decanted, the support is dried as described above, and the catalyst is then regenerated with a mixture of hydrogen and nitrogen (20 parts by volume of hydrogen and 80 parts by volume of nitrogen) first at 300 ° C for 2 hours and then at 550 ° C pn for 5 hours. The regenerated catalyst is then saturated with 680 ml of a solution containing 9.5 g of silver nitrate, 15 g of glycolic acid, 28.6 g of barium nitrate and 5.3 g of potassium nitrate. The saturated catalyst is left in the air for 5 hours, dried as above and finally calcined for 6 hours at 450 ° C.

The finished catalyst has the following composition:

0.5% rhodium;

0.15% by weight of platinum;

0.6% silver by weight;

0.55% by weight melting;

1,5% by weight of barium and

0.2% by weight of potassium.

The catalyst thus prepared was subjected to the same tests with the same raw material as in Example 1, and the following results were obtained:

mp = 450 ° C;

mp = 475 ° C;

stability = 16 ^° C;

benzene formation selectivity = 98 mol percent;

benzene yield = 68.6 mol%, degree of benzene ring cleavage = 1.4%.

The values obtained are shown in Table 2 below.

Example 9 (comparative)

The catalyst was prepared in the same manner as described in Example 7 except that the saturation solution B (590 ml) now contained only 32.5 g of uranyl nitrate hexahydrate and 40 g of citric acid monohydrate. Otherwise, the preparation is the same as in Example 7. The finished catalyst has the following composition:

0,6% by weight of rhodium and

1.5% by weight of uranium.

Catalyst tests carried out in the same way and with the same raw material as in Example 1 gave the following results:

mp = 488 ° C;

mp = 519 ° C;

stability = 31 ° C;

benzene ring selectivity = 88.5 mol%;

benzene yield = 61.95 mol%; degree of benzene ring cleavage = 8.05%.

The values obtained are shown in Table 2. Example 10

1000 g of aluminum oxide as in Example 1 are saturated with an aqueous solution containing 6.3 g of rhodium in the form of rhodium trichloride hydrate, 2.1 g of palladium in the form of palladium chloride and 40 ml of hydrochloric acid (d20 = 1.19). The solution is recycled through the support column for 5 hours, then poured off and the support is dried at 50, 100, 150 and 200 ° C for 2 hours. The catalyst is then saturated with a solution of 550 ml containing 9.2 g of gold in the form of gold chloride and 6.5 g of ammonium perrhenate. After drying under the above conditions, the catalyst is annealed by a stream of air at 400 ° C. After cooling, the catalyst is saturated with 550 ml of a solution containing 26.7 g of potassium nitrate and 0.88 g of rubidium nitrate. The catalyst is dried again as described above and then regenerated with a stream of hydrogen for 6 hours at 540 ^° C. The catalyst thus prepared contains:

0.6% rhodium;

0.2% palladium;

0.9% gold by weight;

0.45% by weight melting;

% of potassium and

0.5% rubidium by weight.

This catalyst was tested under the same conditions and with the same raw material as described in Example 1. The tests gave the following results:

mp = 464 ° C;

mp = 479 ° C;

stability = 15 ° C;

benzene formation selectivity = 96.9 mol%;

benzene yield = 67.8 mole percent; degree of benzene ring cleavage = 2.2%.

The values obtained are shown in Table 2 below.

Example 11

1000 g of the carrier described in Examples 1 to 3 are saturated with 1500 ml of the solution it contains

1.1 g of rhodium in the form of rhodium trichloride hydrochloride 16, 1 g of ammonium perrhenate and 50 ml of hydrochloric acid [d20 = 1.19]. After 5 hours, the excess solution is decanted and the catalyst is dried for 3 hours at 50, 100 and 180 ° C. The catalyst is then saturated with 580 ml of a solution containing 1.4 g of copper chloride dihydrate, 2.1 g of lithium nitrate and 12 ml of acetic acid. The catalyst is then dried as described above and calcined for 2 hours with a stream of air at 400 ° C. The finished catalyst thus prepared contains 0.1% rhodium, 0.05% rhenium, 0.05% copper, 0.02% lithium. This catalyst was subjected to the same tests with the same raw material as described in Example 1. The temperature at which 70% of the toluene conversion was reached was 590 ° C after 50 hours. Furthermore, the test was interrupted due to too high temperatures. The selectivity of benzene formation is 96.2 mole percent, benzene yield is 67.5 mole percent, and the degree of benzene ring cleavage is 2.5%.

The test results are shown in Table 2 below.

Example 12

1000 g of the carrier of Example 1 is saturated with 1500 ml of a solution containing 8.3 g of rhodium in the form of rhodium trichloride hydrate, 0.72 g of iridium in the form of chloriridic acid, 5 g of ruthenium in the form of ruthenium trichloride hydrate, 44 g of ammonium perrhenate and 50 ml of hydrochloric acid (d20) = 1.19). After 5 hours the excess solution was decanted off and the catalyst was dried for 3 hours at 50, 100, 150 and 200 ° C. The dried catalyst is then saturated with 580 ml of a solution containing 37.5 g of sodium nitrate, 50 g of cesium nitrate, 104 g of beryllium nitrate hydrate and 31.5 g of silver nitrate. The catalyst is dried again as described above and then calcined with a stream of air at 400 ° C for 2 hours. The prepared catalyst thus prepared has the following composition:

rhodium 0.81% by weight;

iridium 0.7% by weight;

ruthenium 0.5% by weight;

rhenium 1.95% by weight;

silver 1.93% by weight;

sodium 1.0% by weight;

cesium 3.5% by weight; and beryllium 0.5% by weight.

This catalyst was tested under the same conditions and with the same raw material as described in Example 1. The tests gave the following results:

mp = 462 ° C;

mp = 478 ° C;

stability = 16 ° C;

benzene ring selectivity = 96.1 mol%;

benzene yield - 67.2 mol%; degree of benzene ring cleavage = 2.8%.

The values obtained in the tests of the catalysts according to Examples 4 to 12 are shown in Table 2 below.

The catalyst of Example 9 serves as a comparative example and does not fall within the scope of the invention. The addition of rhenium and copper (Example 7) to the rhodium-uranium system causes an increase in activity, selectivity and stability. In any case, the addition of rhenium and copper leads to catalysts containing noble metals VIII. groups of the Periodic Table of the Elements, alkali metals, alkaline earth metals, as well as copper, silver or gold, to improve the catalytic properties.

Example 13

In order to demonstrate the dehydrocyclization properties of the catalysts, a new series of experiments was carried out with the catalysts of Examples 1, 2, 7 and 9, using as a raw material a mixture of the following percentages:

toluene - 88.2 xylenes - 2.7, n-heptane - 9.1.

The experiments were carried out under the same conditions as described in Examples 1 to 12, but the experiment time was limited to 100 hours. The n-heptane conversion was above 99.5% in all experiments. Unreacted toluene and xylenes are recycled to the reactor. The results of the experiments are shown in Table 3. In the same table, the results of the experiments according to Examples 1, 2, 7 and 9 are repeated, using a mixture of toluene and xylenes as raw material.

The conversion, selectivity, and benzene yield were calculated as in Example 1, the results refer only to aromatic hydrocarbons (n-heptane not included). Surprisingly, using a mixture of toluene, xylenes and n-heptane, using the catalysts of Examples 2 and 7, yields of benzene rings were higher than their starting material content (selectivity of benzene formation over 100 mole percent). This effect is achieved due to the dehydrocyclization of n-heptane under experimental conditions. At the same time, the conversion to the new feedstock using the catalysts of Examples 1 and 9 leads to a substantial decrease in activity without improving selectivity.

The simultaneous presence of rhenium and copper brings a significant selectivity effect when using mixtures of aromatic and non-aromatic hydrocarbons. Similar results are obtained by adding rhenium-silver and rhenium-gold systems.

Example 14

The catalysts of Examples 1 and 2 are used in dealkylation of a real hydrocarbon feedstock consisting of a hydrotreated pyrolysis gasoline fraction having the following composition:

non-aromatic hydrocarbons 30.7% by weight;

benzene 24.2% by weight;

toluene 20.1% by weight;

C5-benzene hydrocarbons 15.3% by weight; C9-benzene hydrocarbons 6.4% by weight and C10-benzene hydrocarbons 3.2% by weight.

The sulfur content of the feedstock is below 0.5 ppm. The test results are shown in Table 4.

Since the calculation of the selectivity in the process under the given conditions is difficult, the selectivity was calculated from the benzene hydrocarbon yield and estimated in mole percent on the benzene hydrocarbon content of the feedstock.

TABLE 4 Cat.

temperature yield yield yield Noc: 2 ° C likvid. benzene arom. uhl. prod. % ^! % wt. in avg. sur. weight % by weight

sklad. liquid product non-aromatic arom. C6 C7 Ce C9 C10

1 480 75.4 37.6 99.2 2 470 79.3 38.6 105.0 From the table 4 is obviously the catalyst with

the addition of copper and rhenium (according to Example 2) is more active and the aromatic hydrocarbon content of the end product obtained using this catalyst is higher than the aromatic content of the starting material. Using a rhenium-free catalyst (according to Example 1), a yield of benzene hydrocarbons exceeding 100% is not achieved. In describing the specific examples15,7 49,9 21,7 7,9 2,3 2,5

13,3 48,7 24,1 8,9 1,9 2,9 Special embodiments have been used in the practice of the invention. However, it is to be understood that each term covers all equivalents which fulfill the same function and which can be used to accomplish the same tasks as the present invention.

All changes and modifications should not be construed as limiting the spirit and scope of the invention as defined by the present invention.

TABLE 1 Catalyst composition operating temperature at 70% conversion for 100 h to 1100 h wt. Low: 14 ° C

0.58 Rhodium, 0.33 copper, 1.5 potassium,

0.3 Calcium 0.58 rhodium, 0.57 rhenium, 0.33 copper, 445 471 0.3 calcium, 1.5 potassium 0.58 rhodium, 0.57 rhenium, 1.5 potassium, 460 472 0.3 Calcium 475 496

stability Noc: 2 ° C selectivity of benzene formation after 100 h mol. % benzene yield after 100 h mol. % degree of benzene ring cleavage% 26 94.5 66.15 3.85 12 97.1 68.0 2,0 21 95.8 67.05 2.95

TABLE 2

e.g. catalyst composition operating temperature stability selectivity yield degree of 70% conversion ° C formation of ben- benzene foaming benze- after 100 h after 1100 h after 100 h after 100 h a new circle % wt. Low: 14 ° C mol. % mol. % hu%

0.55 rhodium, 0.56 rhenium, 0.33 copper,

0.2 potassium, 0.4 magnesium, 2 uranium

0.56 rhodium, 0.55 rhenium, 0.32 copper,

0.5 magnesium, 2 barium

0.58 rhodium, 0.51 rhenium, 0.33 copper,

0,8 strontium,

2,2 magnesium

0.6 rhodium, 0.51 rhenium, 0.15 copper,

1,5 uranium

0.60 rhodium, 0.15 platinum, 0.55 rhenium, 0.6 silver, 1.5 barium, 0.2 potassium

0,60 rhodium,

1,5 uranium

0.6 rhodium, 0.2 palladium, 0.45 rhenium, 0.9 gold, 1 potassium,

0,5 rubidium

0.1 rhodium, 0.05 rhenium, 0.05 copper, 0.02 lithium

0.81 rhodium, 0.7 strontium, 0.5 rubidium, 1.95 rhenium, 1.93 silver, 1 sodium, 1.9 cesium, 2.1 beryllium

455 466 11 97.7 68.4 1.6 460 472 12 97.6 68.3 1.7 455 468 13 97.4 68.2 1,8 452 463 11 97.2 68.05 1.95 459 475 16 98.0 68.6 1.4 488 519 31 88.5 61.95 8.05 464 479 15 Dec 96.9 67.8 2.2 590 (after 50 h) 96.2 67.4 2.6 462 478 16 96.1 67.2 2.8

TABLE 3 raw material: toluene + xylenes (eg 1, 2, 7, 9) raw material: toluene + xylenes +

Claims (1)

, '+ n-heptane (ex. 13) ex. catalyst composition temperature at benzene formation selectivity mol. % yield of benzene mol. % temperature at conversion 70% Noc: 2 ° C benzene formation selectivity mol. % yield of benzene mol. % % wt. conversion of 70 ° / o after 100 h ^J C 1 0.58 rhodium, 0.33 copper, 1.5 potassium, 0.3 Calcium 445 94.5 66.15 469 94.0 65.8 2 0.58 rhodium, 0.57 rhenium, 0.33 copper, 0.3 calcium, 1.5 potassium 460 97.1 68.0 465 102 71.4 7 0.6 rhodium, 0.51 rhenium, 0.15 copper, 1,5 uranium 452 97.2 68.05 458 102.5 71.75 9 0,6 rhodium, 1,5 uranium 488 88.5 61.95 502 87.8 61.50 OBJECT OF INVENTION Catalyst for the alkylation of alkylbenzenes by the reaction of water vapor with a hydrocarbon feedstock consisting of at least one alkylbenzene or a mixture of at least one alkylbenzene with a non-aromatic hydrocarbon consisting of alumina as a carrier on which active ingredients selected from noble metals VIII are applied. groups of the periodic system of elements such as platinum, palladium, rhodium, rutenium, yridium, osmium, at least one metal selected from the group consisting of lithium, sodium, potassium, rubidium, cesium, beryllium, magnesium, calcium, strontium, barium and uranium as well as at least one metal selected from the group consisting of copper, silver and gold, characterized in that it further comprises rhenium in a concentration of 0.05 to 2.0% by weight, the other components of the catalyst being at least one noble metal selected from VIII. groups of the Periodic Table of the Elements at a total concentration of 0.1 to 2.0% by weight with at least one metal selected from the group consisting of lithium, sodium, potassium, rubidium, cesium, beryllium, magnesium, calcium, strontium, barium and uranium; At least one metal selected from the group consisting of copper, silver and gold in a total concentration of 0.05 to 2.0% by weight and the remainder represented by an alumina carrier in a concentration by weight of up to 100%.