RU2586069C1 - Catalyst for synthesis of hydrocarbons from co and h2 and preparation method thereof - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to chemical industry, including petroleum and gas chemistry, and can be applied during preparation of catalysts for producing hydrocarbons from CO and H₂ via Fischer-Tropsch synthesis. Catalyst contains in wt.%: cobalt 16.1-19.0, aluminium additives 0.8-1.0, silica gel carrier - the rest. Obtaining catalyst includes drying carrier at 140-160 °C for 2-4 hours, wetting carrier with aqueous cobalt nitrate solution of concentration 35-55 wt.% with adding aluminium nitrate in weight ratio Co:Al₂O₃ 100:5 in impregnation solution. Then catalyst is dried in two stages at 80-100 °C and at 100-150 °C for 2-4 hours and fired at 250-300 °C for 4-6 hours. Catalyst activation is performed with hydrogen at 380-400 °C for 0.75-1 h.

EFFECT: technical result is obtaining cobalt-aluminium-silicate catalyst with high catalytic activity and selectivity relative to C₅₊ hydrocarbons formation and reduced selectivity relative to methane formation.

2 cl, 1 dwg, 6 ex

Description

The invention relates to the chemical industry, including petrochemistry and gas chemistry, and can be used in the preparation of catalysts for the process of producing hydrocarbons from CO and H ₂ according to the Fischer-Tropsch method.

In recent years, most of the catalysts for the Fischer-Tropsch process have been prepared using alumina modifications as a porous support, primarily γ-Al ₂ O ₃ , less commonly, various oxide supports, including silicon dioxide (SiO ₂ ).

Known cobalt catalyst obtained by the method of impregnation of a porous carrier, including silicon dioxide (Patent RU No. 2252072 C2, B01J 23/75, B01J 3704, 05.20.2005, Bull. No. 14). The catalyst precursor may contain: from 5-70, preferably 20-50, preferably 25-40 g of cobalt per 100 g of support; in addition - the addition of palladium, platinum, ruthenium or a mixture thereof with a mass ratio to metallic cobalt from 0.01: 100 to 0.3: 100.

The disadvantages of the catalyst are: obtaining a precursor with a high content of cobalt - an expensive active component of the catalyst; the advisability of using alloying additives - palladium, platinum, ruthenium, or mixtures thereof - expensive and scarce metals.

Known cobalt catalyst obtained by the method of impregnation of a porous carrier, including silicon dioxide, containing 3-50% of the mass. cobalt (or / and ruthenium) per catalyst. The catalyst precursor is zirconium, based on zirconium oxide, when the carrier is pretreated by impregnation, it is in an aqueous solution of zirconium in a volume quantity of 2 or more times the amount of silicon dioxide (Patent RU No. 2436832 C2, C10G 2/00, С07С 1/04, С07С 9/00, B01J 23/75, B01J 37/08, B01J 21/06, B01J 23/46, B01J 37/02, 12/20/2011, Bull. No. 35).

The disadvantages of the catalyst are: the use of a catalyst precursor in the form of zirconium oxide; the inclusion in the active component of significant quantities of expensive metals - cobalt (or / and ruthenium).

The closest analogue (prototype) is a catalyst for the synthesis of hydrocarbons from CO and H ₂ according to the Fischer-Tropsch method, obtained by impregnation, including cobalt and silica gel brand KSKG, composition 20% Co / SiO ₂ (article Lapidus A.L., Krylova A. Yu., Tsapkina MV, Erofeeva AB, Reyzina AV The influence of the activation method of the catalyst 20% Co / SiO ₂ on the main indicators of Fischer-Tropsch synthesis / Chemistry of solid fuels, 2004. - No. 4. - p. .40-45).

The disadvantages of the catalyst are: low activity and selectivity in the synthesis of C ₅₊ hydrocarbons; relatively high content of the active component - cobalt.

A known method of preparing a cobalt catalyst by the method of impregnation of a porous carrier, including SiO ₂ , including: obtaining a catalyst precursor in the form of cobalt oxide of a certain block structure by the method of impregnating a powder carrier with a cobalt salt, drying, calcining in a fluidized bed, reduction; preparation of a cobalt catalyst during subsequent processing of the catalyst precursor by repeating the above operations (Patent RU No. 2252072 C2, B01J 23/75, B01J 3704, 05.20.2005, Bull. No. 14).

The disadvantages of the method are: the need to obtain a catalyst precursor by impregnation, drying, calcination and recovery; the preparation of the catalyst during the subsequent processing of the catalyst precursor by repeating the above operations.

A known method of preparing a cobalt catalyst by the method of impregnation of a porous carrier, including SiO ₂ , comprising: obtaining a catalyst precursor in the form of zirconium oxide, which is selectively deposited near the outer surface of the carrier by impregnation with an aqueous solution of acid and zirconium; heat treatment to obtain a carrier in which zirconium in the form of oxide is deposited on the surface of the carrier; application of cobalt (and / or ruthenium) to the carrier (Patent RU No. 2436832 C2, C10G 2/00, C07C 1/04, C07C 9/00, B01J 23/75, B01J 37/08, B01J 21/06, B01J 23/46, B01J 37/02, 12.20.2011, Bull. No. 35).

The disadvantage of this method is: the need to obtain a catalyst precursor by the method of impregnation and calcination of the catalyst carrier.

The closest analogue (prototype) is a method for producing a catalyst, comprising: preparing a carrier - silica gel of the KSKG brand, during calcination at a temperature of 450 ° C; impregnation of an aqueous solution of cobalt nitrate; heat treatment; catalyst activation - reduction, at a temperature of 450 ° C or processing in the form of sequential reduction at a temperature of 450 ° C, oxidation and re-reduction at a temperature of 450 ° C.

The disadvantages of the method are: low activity of the catalyst in the process of synthesis of hydrocarbons With ₅₊ ; the need to use high temperatures in the synthesis of hydrocarbons from CO and H ₂ and in the preparation of the catalyst at the stages of preparation of the carrier and activation of the catalyst; additional treatments to activate the catalyst.

The objective of the present invention is to obtain a cobalt-aluminum-silica gel synthesis catalyst for hydrocarbons from CO and H ₂ according to the Fischer-Tropsch method with enhanced catalytic properties - high selectivity for the formation of C ₅₊ hydrocarbons (close to 90%), reduced selectivity for methane formation; characterized by a low optimum temperature for the synthesis of hydrocarbons; with a significant reduction in the content of the expensive active component of the catalyst - cobalt, as a result of the introduction of aluminum additives, a significant simplification of the catalyst technology and obtaining the corresponding economic effect.

The task, according to the invention, in terms of the composition of the cobalt aluminum silica gel catalyst is solved by using a catalyst for the synthesis of hydrocarbons from CO and H ₂ , selective for the formation of hydrocarbons With ₅₊ , including cobalt and silica gel carrier, and the catalyst contains 16.1-19, 0% of the mass. cobalt and 0.8-1.0% of the mass. aluminum additives.

The task according to the invention, in terms of the method for producing cobalt aluminum silica gel catalyst, is solved by using a method for producing a catalyst selective for the formation of C ₅₊ hydrocarbons containing the active component cobalt and a silica gel carrier, including preliminary preparation of the carrier, impregnating the carrier with an aqueous solution of cobalt nitrate , heat treatment and activation of the catalyst, and the preliminary preparation of the carrier is carried out in the drying mode for 2-4 hours at a temperature re 140-160 ° C, at the stage of impregnation of the carrier in an aqueous solution of cobalt nitrate with a concentration of 35-55% of the mass. an aluminum additive is introduced in the form of aluminum nitrate at a mass ratio of Co: Al ₂ O ₃ in an impregnation solution of 100: 5, the heat treatment of the catalyst includes drying - first 2-4 hours at temperatures of 80-100 ° C, then 2-4 hours at a temperature of 100- 150 ° C, calcination for 4-6 hours at a temperature of 250-300 ° C, the activation of the catalyst is carried out with hydrogen for 0.75-1 h at a temperature of 380-400 ° C.

The proposed composition of the cobalt-aluminum-silica gel catalyst with enhanced catalytic properties during the synthesis of hydrocarbons from CO and H ₂ , primarily in relation to the formation of C ₅₊ hydrocarbons, is characterized by: the possibility of synthesis at lower temperatures, thereby providing more efficient heat removal from the reaction zone; a decrease in the cobalt content in the catalyst, which, taking into account the cost of cobalt, makes it possible to reduce the cost of the finished product.

The proposed method for the preparation of a cobalt-aluminum-silica gel catalyst with enhanced catalytic properties is characterized by: reducing energy consumption and obtaining an appropriate economic effect when the temperature is reduced at all stages of the catalyst heat treatment — replacing preliminary calcination by drying, during drying and calcination of wet catalyst and activation (recovery) of the finished catalyst; the lack of additional activation of the catalyst in the form of a recovery cycle, activation and re-recovery.

The technical result obtained - the creation of an active and selective catalyst is ensured by the fact that the introduction of an aluminum additive while reducing the cobalt content in the catalyst contributes to the formation of an optimal crystalline structure of the active component, and in the process of preparing the catalyst, conditions are created for the formation of such an active component structure, which, in turn, determines the high activity and selectivity of the catalyst and is confirmed by a greater than in the known method, the amount of formed C ₅₊ hydrocarbons with less - at 20-30 ° C, temperature of the synthesis, which is especially important for the Fischer-Tropsch process.

The study of the properties of catalysts in the synthesis of hydrocarbons from CO and H ₂ according to the Fischer-Tropsch method was carried out in a tubular reactor with a stationary catalyst bed at a pressure of 0.1 MPa in the temperature range 150-200 ° C. The molar ratio of CO: H ₂ in the synthesis gas was 1: 2.

The activity of the catalysts was judged by the conversion of CO, selectivity and the yield of hydrocarbons per 1 nm ^{3 of the} gas mixture.

The figure 1 shows a table of comparative data on the activity and selectivity of the catalysts in the synthesis of hydrocarbons from CO and H ₂ .

The invention is carried out in the following way.

The calculated amount of cobalt nitrate at a temperature of 70-80 ° С is dissolved in distilled water with stirring, after which aluminum is added to the impregnation solution in the form of aluminum nitrate, the calculated amount of which is determined based on the mass ratio of Co: Al ₂ O ₃ in solution 100 :5. Into the impregnating solution, immerse 50 cm ^{3 of} carrier with a temperature of 60-80 ° C, dried for 2-4 hours at a temperature of 140-160 ° C. Impregnation is carried out for 0.5 hours at a temperature of 70-80 ° C, stirring. The wet catalyst is dried for 2-4 hours at a temperature of 80-100 ° C, until the adhesion of the granules is eliminated; heat treatment - first 2-4 hours at a temperature of 100-150 ° C, then 4-6 hours at a temperature of 250-350 ° C; activation (reduction) is carried out with hydrogen at a temperature of 380-400 ° C for 0.75-1.0 hours at a volumetric rate of hydrogen of 1000 h ^-1 .

To implement the method, silica gel with a granule size of 2-3 mm is used as a catalyst carrier. In particular, large-porous, granular, KSKG grades in accordance with GOST 3956-76.

The synthesis of hydrocarbons from CO and H ₂ according to the Fischer-Tropsch method is carried out in a tubular reactor with a stationary catalyst bed at a pressure of 0.1 MPa in the temperature range 150-200 ° C. The molar ratio of CO: H ₂ in the synthesis gas was 1: 2.

Example 1

194.50 g of cobalt nitrate in the form of Co (NO ₃ ) ₂ · 6H ₂ O at a temperature of 80 ° C, while stirring, dissolved in 50.15 g of distilled water, after which aluminum is added to the impregnation solution in a weight ratio of Co: Al ₂ O ₃ in an impregnating solution of 100: 5 in the form of 15.57 g of aluminum nitrate - Al (NO ₃ ) ₃ · 9H ₂ O, and immersed in 50 cm ^{3 of} silica gel with a temperature of 80 ° C, dried for 4 hours at a temperature of 150 ° C. Impregnated for 0.5 h at a temperature of 80 ° C, stirring. The wet catalyst is dried for 4 hours at a temperature of 80 ° C, until the adhesion of the granules; heat treated first 4 hours at temperatures of 125 ° C, then 6 hours at a temperature of 300 ° C; activation (reduction) is carried out with hydrogen at a temperature of 380 ° C for 1.0 h at a space velocity of hydrogen of 1000 h ^-1 .

The catalyst contains 20.0% of the mass. cobalt. The degree of reduction of the catalyst is 52%.

Example 2

229.56 g of cobalt nitrate in the form of Co (NO ₃ ) ₂ · 6H ₂ O at a temperature of 80 ° C, while stirring, dissolved in 32.04 g of distilled water, after which aluminum is added to the impregnation solution in a weight ratio of Co: Al ₂ O ₃ in an impregnation solution of 100: 5 in the form of 18.37 g of aluminum nitrate - Al (NO ₃ ) ₃ · 9H ₂ O, and immersed in 50 cm ^{3 of} silica gel with a temperature of 80 ° C, dried for 4 hours at a temperature of 150 ° C. Impregnated for 0.5 h at a temperature of 80 ° C, stirring. The wet catalyst is dried, heat treated, activated (reduced) with hydrogen, as described in example 1.

The catalyst contains 22.1% of the mass. cobalt and 1.2% of the mass. aluminum. The degree of catalyst reduction is 56%.

Example 3

176.76 g of cobalt nitrate in the form of Co (NO ₃ ) ₂ · 6H ₂ O at a temperature of 80 ° C, while stirring, dissolved in 51.84 g of distilled water, after which aluminum is added to the impregnation solution in a weight ratio of Co: Al ₂ O ₃ in an impregnation solution of 100: 5 in the form of 14.14 g of aluminum nitrate - Al (NO ₃ ) ₃ · 9H ₂ O, and immersed in 50 cm ^{3 of} silica gel with a temperature of 80 ° C, dried for 4 hours at a temperature of 150 ° C. Impregnated for 0.5 h at a temperature of 80 ° C, stirring. The wet catalyst is dried, heat treated, activated (reduced) with hydrogen as described in example 1.

The catalyst contains 19.0% of the mass. cobalt and 1.0% of the mass. aluminum. The degree of catalyst reduction is 53%.

Example 4

152.72 g of cobalt nitrate in the form of Co (NO ₃ ) ₂ · 6H ₂ O at a temperature of 80 ° C, while stirring, dissolved in 60.73 g of distilled water, after which aluminum is added to the impregnation solution in a weight ratio of Co: Al ₂ O ₃ in an impregnating solution of 100: 5 in the form of 12.22 g of aluminum nitrate - Al (NO ₃ ) ₃ · 9H ₂ O, and immersed in 50 cm ^{3 of} silica gel with a temperature of 80 ° C, dried for 4 hours at a temperature of 150 ° C. Impregnated for 0.5 h at a temperature of 80 ° C, stirring. The wet catalyst is dried, heat treated, as described in example 1, activated (restored) with hydrogen at a temperature of 400 ° C for 0.83 hours at a space velocity of hydrogen of 1000 h ^-1 .

The catalyst contains 17.6% of the mass. cobalt and 0.9% of the mass. aluminum. The degree of reduction of the catalyst is 57%.

Example 5

130.32 g of cobalt nitrate in the form of Co (NO ₃ ) ₂ · 6H ₂ O at a temperature of 80 ° C, while stirring, dissolved in 74.58 g of distilled water, after which aluminum is added to the impregnation solution in a weight ratio of Co: Al ₂ O ₃ in an impregnating solution of 100: 5 in the form of 10.43 g of aluminum nitrate - Al (NO ₃ ) ₃ · 9H ₂ O, and immersed in 50 cm ^{3 of} silica gel with a temperature of 80 ° C, dried for 4 hours at a temperature of 150 ° C. Impregnated for 0.5 h at a temperature of 80 ° C, stirring. The wet catalyst is dried, heat treated, as described in example 1, activated (restored) with hydrogen at a temperature of 400 ° C for 0.83 hours at a space velocity of hydrogen of 1000 h ^-1 .

The catalyst contains 16.1% of the mass. cobalt and 0.8% of the mass. aluminum. The degree of reduction of the catalyst is 58%.

Example 6

109.44 g of cobalt nitrate in the form of Co (NO ₃ ) ₂ · 6H ₂ O at a temperature of 80 ° C, while stirring, dissolved in 87.21 g of distilled water, after which aluminum is added to the impregnation solution in a weight ratio of Co: Al ₂ O ₃ in an impregnation solution of 100: 5 in the form of 8.76 g of aluminum nitrate - Al (NO ₃ ) ₃ · 9H ₂ O, and immersed in 50 cm ^{3 of} silica gel with a temperature of 80 ° C, dried for 4 hours at a temperature of 150 ° C. Impregnated for 0.5 h at a temperature of 80 ° C, stirring. The wet catalyst is dried, heat treated, as described in example 1, activated (restored) with hydrogen at a temperature of 400 ° C for 0.75 hours at a space velocity of hydrogen of 1000 h ^-1 .

The catalyst contains 13.9% of the mass. cobalt and 0.6% of the mass. aluminum. The degree of reduction of the catalyst is 50%.

Generalized comparative data on the assessment of the catalytic properties obtained using the known and proposed catalysts in the synthesis of hydrocarbons from CO and H ₂ are shown in the table.

The above results show that the proposed composition and method of preparation allow the process of synthesis of hydrocarbons from CO and H ₂ at a lower temperature and to obtain a catalyst characterized by high catalytic activity and selectivity for the formation of C ₅₊ hydrocarbons and reduced selectivity for the formation of a by-product methane .

The optimum content of cobalt in the catalyst and the addition of aluminum are, respectively, mass%: cobalt - 16.1-19.0; aluminum - 0.8-1.0.

The introduction of cobalt and the addition of aluminum in smaller quantities is insufficient to improve the properties of the catalyst. An increase in the content of cobalt and the addition of aluminum does not provide an improvement in the activity and selectivity of the catalyst during the synthesis of hydrocarbons.

The invention allows to reduce the amount of cobalt required to obtain a catalyst; significantly simplify the catalyst preparation technology, including eliminating the need for additional activation; significantly reduce energy consumption during the implementation of the technology as a result of drying the carrier and catalyst, heat treatment and activation (recovery) of the catalyst in the region of lower temperatures.

Claims (2)

1. The catalyst for the synthesis of hydrocarbons from CO and H ₂ , selective for the formation of hydrocarbons C ₅₊ , including cobalt and silica gel carrier, characterized in that it contains 16.1-19.0% of the mass. cobalt and 0.8-1.0% of the mass. aluminum additives. 2. The method for producing a catalyst according to claim 1, selective for the formation of C ₅₊ hydrocarbons, containing the active component cobalt and a silica gel carrier, including preliminary preparation of the carrier, impregnation of the carrier with an aqueous solution of cobalt nitrate, heat treatment and activation of the catalyst, characterized in that preliminary preparation of the carrier is carried out in the drying mode for 2-4 hours at a temperature of 140-160 ° C, at the stage of impregnation of the carrier into an aqueous solution of cobalt nitrate with a concentration of 35-55% by weight. an aluminum additive is introduced in the form of aluminum nitrate at a mass ratio of Co: Al ₂ O ₃ in an impregnation solution of 100: 5, the heat treatment of the catalyst includes drying - first 2-4 hours at temperatures of 80-100 ° C, then 2-4 hours at a temperature of 100- 150 ° C, and calcination for 4-6 hours at a temperature of 250-300 ° C, the activation of the catalyst is carried out with hydrogen for 0.75-1 h at a temperature of 380-400 ° C.

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