RU2292952C1 - Catalyst for selective hydrogenation of diene hydrocarbons - Google Patents

Abstract

FIELD: hydrogenation-dehydrogenation catalysts.

SUBSTANCE: invention relates to production of catalyst for selective hydrogenation of diene hydrocarbons, which can be used for hydrofining of liquid pyrolysis products. Catalyst is an active palladium component deposited in amount 0.01-1.0% on inorganic porous support. The latter has mesopores having diameters no less than 4 nm and no bigger than 20 nm, constituting 80 to 98% of the total pore volume in the catalyst, and is characterized by specific surface value 10 to 40 m2/g and total pore volume 0.1 to 0.2 cc/g.

EFFECT: increased activity and selectivity of diene hydrogenation process.

2 cl, 1 tbl, 11 ex

Description

The invention relates to the field of production of catalysts, specifically to the production of catalysts for the selective hydrogenation of diene hydrocarbons, and can be used for hydrofining of liquid pyrolysis products.

In the two-stage process of catalytic hydrogenation of impurities of unsaturated hydrocarbons in the pyrolysis gasoline fractions after the first hydrogenation step, the catalyst should provide a residual content of diene compounds in terms of the diene number not higher than 1 g of iodine per 100 g of raw material. A higher content of diene hydrocarbons reduces activity and shortens the life of the catalyst in the second stage of the olefin hydrogenation process.

A known catalyst for the selective hydrogenation of unsaturated hydrocarbons, representing 0.01-1.0 wt.% Palladium supported on an alumina carrier with an average pore diameter of 40 to 400 nm, in which at least 80% of the pores have a diameter in the region of 20 up to 600 nm, a specific surface area of not more than 50 m ² / g and a pore volume of 0.2 cm ³ / g to 1.0 cm ³ / g (US Patent No. 4762956, IPC C 07 C 005/08, published 09.09. 1988).

The disadvantages of this catalyst are not sufficiently high activity and selectivity in the processes of selective hydrogenation of diene hydrocarbons in liquid pyrolysis fractions.

Known supported palladium catalyst for the selective hydrogenation of diene compounds in the C ₅ -C ₁₀ fraction of pyrolysis gasoline based on aluminum oxide, which has micro- and mesopores with an average diameter of 4-4.5 nm and macropores with an average diameter of 500-600 nm, in which macropores account for 33-35% of the total pore volume. Moreover, the specific surface area of the catalyst exceeds 200 m ² / g, and the pore volume is more than 1.0 cm ³ / g (US Patent No. 5516851, IPC B 01 J 23/44, publ. 05/14/1996). The described catalyst also does not allow to achieve a high conversion of diene hydrocarbons in gasoline pyrolysis.

Closest to the proposed invention is a catalyst for the selective hydrogenation of diene hydrocarbons containing 0.005-0.5 wt.% Palladium on an alumina support having a total pore volume of 0.3-0.6 cm ³ / g, specific surface area from 10 cm ³ / g to 60 cm ³ / g and an average pore diameter in the range of 40 nm to 100 nm (US Patent No. 6,797,669, IPC B 01 J 023/42; B 01 J 023/44; B 01 J 023/40; B 01 J 023/58; B 01 J 023/72, publ. 09/28/04). The activity and selectivity of this catalyst is not high enough in the hydrogenation reaction of diene compounds.

The objective of the invention is to provide a catalyst that allows to achieve high activity and selectivity in the processes of selective hydrogenation of diene hydrocarbons. As indicators characterizing the activity of the catalyst, the value of the diene number of the contact gas and the conversion of diene hydrocarbons are accepted. As an indicator of the selectivity of the catalyst, the relative increase or loss of aromatic hydrocarbons in the feed stream is taken.

The problem is solved by the development of a catalyst for the selective hydrogenation of diene hydrocarbons, which is palladium on a porous support that contains mesopores with a diameter of at least 4 nm and no more than 20 nm, which determine from 80 to 98% of the total pore volume in the catalyst, characterized by one maximum distribution of volumes then in the range of diameters from 4 nm to 20 nm, has a specific surface area of 10 m ² / g to 40 m ² / g and a total pore volume of 0.1 cm ³ / g to 0.2 cm ³ / g.

It is possible to use a catalyst containing palladium on a porous support that contains mesopores with a diameter of at least 4 nm and no more than 20 nm, which determine from 80 to 98% of the total pore volume in the catalyst, characterized by one maximum pore volume distribution in the diameter range from 4 nm to 20 nm, has a specific surface area of 10 m ² / g to 40 m ² / g and a total pore volume of 0.1 cm ³ / g to 0.2 cm ³ / g in the following ratio of components, wt.%:

Pd 0.01-1.0;

the porous carrier is the rest.

Palladium dispersed on the surface of a porous carrier is widely used in the selective hydrogenation of diene hydrocarbons. The properties of the carrier determine the dispersion, oxidation state, palladium distribution density, acid-base surface characteristics, heat transfer and diffusion processes in its porous system. The most common way to evaluate the parameters of a porous system of catalysts - the specific surface area, total pore volume, pore shape, average pore diameter and pore size distribution - is the method of low-temperature nitrogen adsorption. According to the accepted classification, micro-, meso- and macropores with diameters <2, 2-50,> 50 nm, respectively, are isolated. An analysis of the differential curves of pore volumes by size, by the position of the corresponding maxima makes it possible to identify pores of dominant sizes and their contribution to the total porometric volume in a given catalytic system. Due to the progress of the selective hydrogenation of diolefins in the diffusion region, it is important to form the optimal porous structure of the catalyst, a given pore size, the required specific surface area and pore volume. The conduct of the selective hydrogenation reaction in the microporous region is accompanied by a decrease in the selectivity of the process as a result of diffusion difficulties and secondary processes on the catalyst surface. In the macropore region, a decrease in catalyst activity occurs due to the acceleration of mass transfer processes. The mesoporous region is optimal, since the course of the process in mesopores of a certain size makes it possible to limit both the rate of supply of reagents to the active centers of the catalyst and the removal of reaction products from its porous system and thereby control activity and selectivity.

The catalyst is prepared by impregnating the support with a solution of a palladium-containing compound, followed by exposure to a solution of a palladium-containing compound, removing the solvent and reducing palladium.

As sources of palladium, palladium chloride, palladium bromide, palladium iodide, palladium nitrate, palladium sulfate, palladium sulfide, palladium acetate, palladium acetylacetonate, palladium oxalate in individual forms or in combination with each other can be used.

As the carrier, γ-, β-, η-, δ-, θ-, α-Al ₂ O ₃ in individual forms or in combination with each other, SiO ₂ , TiO ₂ , MgO and others can be used. A method of producing catalyst supports includes the steps of precipitating aluminum, titanium, magnesium or silicic acid hydroxides followed by drying, molding of granules and calcining to oxides. The essence of the methods for the preparation of carriers is described in the monographs of I. M. Kolesnikov “Catalysis and Catalyst Production” (Moscow, Tekhnika Publishing House TUMA GROUP, 2004. - 400 pp.), V. A. Dzisko “Fundamentals of Catalyst Preparation Methods” (Novosibirsk, publishing house "Science", Siberian Branch, 1983. - 264 pp.) and in the publication of V.A. Dzysko, A.P. Karnaukhov, D.V. Tarasova "Physico-chemical principles of synthesis of oxide catalysts" (Novosibirsk, publishing house "Science ", Siberian Branch, 1978. - 384 p.)

The essence of the method for determining the parameters of a porous catalyst system is described in ASTM D 3663-99, “Standard Method for Studying the Surface Area and Pore Volume of Catalysts and Catalyst Carriers”.

In the presence of the proposed catalyst, selective hydrogenation processes are carried out, for example, diene hydrocarbons such as 1,2-butadiene, 1,3-butadiene, isoprene, 1,2-pentadiene, 1,3-pentadiene, 1,2-hexadiene, 1, 3-hexadiene, 1,4-hexadiene, 1,5-hexadiene, 2-methyl-1,2-pentadiene, 2,3-dimethyl-1,3-butadiene, heptadiene, octadiene, nonadiene, decadiene, cyclopentadiene, cyclohexadiene, methylcyclopentadienes, cycloheptadienes, methylcyclohexadiene, dimethylcyclopentadiene, ethylcyclopentadiene, triethylcyclopentadiene, methyloctadiene, dimethylpentadiene, ethylp entadienes, triethylheptadienes in individual forms or in mixtures with each other.

Examples of specific embodiments of the invention.

Example 1

The selective hydrogenation of diene hydrocarbons in the C ₆ -C ₈ fraction of pyrolysis gasoline (table) is carried out in a laboratory reactor with a catalyst volume of 50 cm ³ at a temperature of 50 ° C at the inlet of the reactor, a pressure of 4.3 MPa, a mass dilution of the raw material with hydrogenate equal to 1 : 3, the ratio of hydrogen-containing gas / feed equal to 167 m ³ / m ³ per hour, the volumetric feed rate of 3.6 h ^-1 . After 12 hours of hydrogenation, hourly contact gas samples are taken and analyzed. The catalyst used has the following composition:

Pd 0.30%; Al ₂ O ₃ - the rest.

The alumina support has a specific surface area of 11 m ² / g, a pore volume of 0.1 cm ³ / g, contains mesopores with a diameter of 16 to 20 nm, which accounts for 92% of the total pore volume in the catalyst, and is characterized by a differential maximum at low temperature nitrogen adsorption distribution curve of pore volumes at a diameter of 18.4 nm.

The values of the diene number of the contact gas, the conversion of diene hydrocarbons and the relative increase in aromatic hydrocarbons are presented in the table.

Example 2

The selective hydrogenation of diene hydrocarbons in the C ₆ -C ₈ fraction of pyrolysis gasoline (table) is carried out as described in example 1, using a catalyst of the following composition:

Pd 0.55%; Al ₂ O ₃ - the rest.

The alumina support has a specific surface area of 17 m ² / g, a pore volume of 0.125 cm ³ / g, contains mesopores with a diameter of 8 to 19 nm, which accounts for 87% of the total pore volume in the catalyst, and is characterized by a maximum on the differential distribution curve for low-temperature nitrogen adsorption pore volumes with a diameter of 13 nm.

The values of the diene number of the contact gas, the conversion of diene hydrocarbons and the relative increase in aromatic hydrocarbons are presented in the table.

Example 3

The selective hydrogenation of diene hydrocarbons in the C ₆ -C ₈ fraction of pyrolysis gasoline (table) is carried out as described in example 1, using a catalyst of the following composition:

Pd 0.01%; Al ₂ O ₃ - the rest.

The alumina support has a specific surface area of 25 m ² / g, a pore volume of 0.107 cm ³ / g, contains mesopores with a diameter of 4 to 10 nm, which account for 97% of the total pore volume in the catalyst, and is characterized by a maximum on the differential distribution curve for low-temperature nitrogen adsorption pore volumes with a diameter of 5.9 nm.

The values of the diene number of the contact gas, the conversion of diene hydrocarbons and the relative increase in aromatic hydrocarbons are presented in the table.

Example 4

The selective hydrogenation of diene hydrocarbons in the C ₆ -C ₈ fraction of pyrolysis gasoline (table) is carried out as described in example 1, using a catalyst of the following composition:

Pd 0.30%; Al ₂ O ₃ - the rest.

The alumina support has a specific surface area of 17 m ² / g, a pore volume of 0.172 cm ³ / g, contains mesopores with a diameter of 8 to 15 nm, which account for 81% of the total pore volume in the catalyst, and is characterized by a maximum on the differential distribution curve for low-temperature nitrogen adsorption pore volumes with a diameter of 7.3 nm.

The values of the diene number of the contact gas, the conversion of diene hydrocarbons and the relative increase in aromatic hydrocarbons are presented in the table.

Example 5

The selective hydrogenation reaction of a mixture of isoprene and 1,2-butadiene (table) is carried out as described in example 1, using a catalyst of the following composition:

Pd 1.0%; Al ₂ O ₃ - the rest.

The alumina support has a specific surface area of 38 m ² / g, a pore volume of 0.2 cm ³ / g, contains mesopores with a diameter of 14 to 20 nm, which account for 85% of the total pore volume in the catalyst, and is characterized by a differential maximum at low temperature nitrogen adsorption distribution curve of pore volumes at a diameter of 19.3 nm.

The values of the diene number of the contact gas, the conversion of diene hydrocarbons and the relative increase in aromatic hydrocarbons are presented in the table.

Example 6

The selective hydrogenation of diene hydrocarbons in the C ₆ -C ₈ fraction of pyrolysis gasoline is carried out as described in example 1, using a catalyst of the following composition:

Pd 0.20%; SiO ₂ - the rest.

The silica support has a specific surface area of 10 m ² / g, a pore volume of 0.1 cm ³ / g, contains mesopores with a diameter of 4 to 7 nm, which account for 98% of the total pore volume in the catalyst, and is characterized by a differential maximum at low temperature nitrogen adsorption distribution curve of pore volumes at a diameter of 4.5 nm.

The values of the diene number of the contact gas, the conversion of diene hydrocarbons and the relative increase in aromatic hydrocarbons are presented in the table.

Example 7

The selective hydrogenation reaction of 1,2-hexadiene is carried out as described in example 1, using a catalyst of the following composition:

Pd 0.15%; SiO ₂ - the rest.

The silica support has a specific surface area of 10 m ² / g, a pore volume of 0.18 cm ³ / g, contains mesopores with a diameter of 8 to 12 nm, which account for 98% of the total pore volume in the catalyst, and is characterized by a differential maximum at low temperature nitrogen adsorption pore volume distribution curve with a diameter of 8.3 nm.

The values of the diene number of the contact gas, the conversion of diene hydrocarbons and the relative increase in aromatic hydrocarbons are presented in the table.

Example 8

The selective hydrogenation of isoprene is carried out as described in example 1, using a catalyst of the following composition:

Pd 0.5%; TiO ₂ - the rest.

The titanium oxide support has a specific surface area of 39 m ² / g, a pore volume of 0.152 cm ³ / g, contains mesopores with a diameter of 4 to 20 nm, which account for 88% of the total pore volume in the catalyst, and is characterized by a maximum on the differential distribution curve for low-temperature nitrogen adsorption pore volumes with a diameter of 16.4 nm.

The values of the diene number of the contact gas, the conversion of diene hydrocarbons and the relative increase in aromatic hydrocarbons are presented in the table.

Example 9

The selective hydrogenation of isoprene is carried out as described in example 1, using a catalyst of the following composition:

Pd 0.5%; MgO - the rest.

The magnesium oxide carrier has a specific surface area of 35 m ² / g, a pore volume of 0.115 cm ³ / g, contains mesopores with a diameter of 12 to 20 nm, which account for 90% of the total pore volume in the catalyst, and is characterized by a maximum on the differential distribution curve for low-temperature nitrogen adsorption pore volumes with a diameter of 13.9 nm.

The values of the diene number of the contact gas, the conversion of diene hydrocarbons and the relative increase in aromatic hydrocarbons are presented in the table.

Example 10 (comparisons)

The selective hydrogenation of diene hydrocarbons in the C ₆ -C ₈ fraction of pyrolysis gasoline (table) is carried out as described in example 1, at a hydrogenation reaction temperature of 60 ° C, using a catalyst of the following composition:

Pd 0.3%; Al ₂ O ₃ - the rest.

The alumina support has a specific surface area of 97 m ² / g, a pore volume of 0.35 cm ³ / g, contains mesopores with a diameter of 20 to 70 nm, which account for 70% of the total pore volume in the catalyst, and is characterized by maxima at the differential nitrogen adsorption distribution curve of pore volumes at diameters of 4 and 56 nm.

The values of the diene, bromine number of the contact gas and the conversion of diene hydrocarbons are presented in the table.

Example 11 (comparisons)

The selective hydrogenation of diene hydrocarbons in the C ₆ -C ₈ fraction of pyrolysis gasoline (table) is carried out as described in example 1, at a hydrogenation reaction temperature of 60 ° C, using a catalyst of the following composition:

Pd 0.3%; Al ₂ O ₃ - the rest.

The alumina support has a specific surface area of 58 m ² / g, a pore volume of 0.15 cm ³ / g, contains mesopores with a diameter of 20 to 70 nm, which account for 70% of the total pore volume in the catalyst, and is characterized by a differential maximum at low temperature nitrogen adsorption distribution curve of pore volumes at a diameter of 40 nm.

The values of the diene number of the contact gas, the conversion of diene hydrocarbons and the relative increase in aromatic hydrocarbons are presented in the table.

As can be seen from the above examples, the proposed catalyst is superior in hydrogenating activity to reference catalysts even at a lower palladium content, which is due to the optimization of mass transfer processes in the porous catalyst system. The increase in catalyst selectivity is due to the absence of micropores that impede the diffusion of reagents and reaction products, and the process in the mesoporous catalyst system.

Table Example No. The original hydrocarbon fraction Contact gas Diene numbers; j _2/100 g The concentration of aromatic hydrocarbons,% Diene numbers; j _2/100 g The conversion of diene hydrocarbons,% Relative gain / loss of aromatic hydrocarbons,% one 6.2 21.3 0.25 97.2 +0.73 2 6.2 21.3 0.39 96.5 +0.95 3 4.6 19.7 0,07 98.0 +1.89 four 4.6 19.7 0.09 98.8 + 2.01 5 32,2 - 1.20 96.9 - 6 4.6 19.7 0.54 90.3 0.19 7 32,4 - 1.31 95.4 - 8 34.8 - 1.27 96.8 - 9 34.8 - 1.12 96.1 - 10 (comp.) 2.7 22.7 0.70 92.3 -0.45 11 (comp.) 12.0 36,2 0.90 92.5 -0.36

Claims (2)

1. The catalyst for the selective hydrogenation of diene hydrocarbons, which is palladium on a porous support, containing mesopores with a diameter of at least 4 and not more than 20 nm, causing from 80 to 98% of the total pore volume in the catalyst, characterized by one maximum pore volume distribution in the diameter range from 4 to 20 nm, characterized in that it has a specific surface area of 10 to 40 m ² / g and a total pore volume of 0.1 to 0.2 cm ³ / g. 2. The catalyst according to claim 1, characterized in that the ratio of the components of the catalyst is maintained, wt.%: Palladium 0.01-1.0 Porous carrier Rest