RU2505356C2 - Method of obtaining catalyst and method of synthesis of c2-c4 olefins in presence of catalyst obtained thereof - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: method of obtaining catalyst includes modification of catalyst based on silicoalumophosphates by method of impregnating by water capacity from silicon source solution or impregnation from silicon source solution - trimethyl siloxysilsesquioxane. Obtained catalyst contains from 0.1 to 10 wt % of silicon. As catalyst based on silicoalumophosphates used are molecular sieves of SAPO-18 to SAPO-34 type, for molecular sieves, containing their cocrystallised phases. Method of synthesis of lower olefins includes conversion of carbon-containing raw material in presence of said catalyst. As carbon-containing raw material used is methanol or its water solution, which contains from 25 to 100 wt % of methanol, or dimethyl alcohol, or chloromethane. Conversion is carried out in gas phase at 350-500°C, atmospheric pressure and rate of raw material supply 0.5-15 g/g/h, in the presence of gas-diluent.

EFFECT: ensuring hollow conversion of carbon-containing raw material and increased output of C₂-C₄ olefis.

10 cl, 1 tbl, 17 ex

Description

The invention relates to the refining industry and, more specifically, to a method for producing (synthesis) of C2-C4 olefins.

Lower olefins (C2-C4) are important intermediates in the chemical industry, among which ethylene (C2H4) and propylene (C3H6) are most in demand, of which various polymeric materials (polyethylene, polypropylene, polyvinyl chloride, polystyrene, synthetic rubbers) are produced in large quantities and some products of basic organic synthesis.

Today, lower olefins are obtained mainly by the pyrolysis of gasoline and gas oil fractions of oil. However, the steady increase in oil prices, its limited reserves (only 30–40 years) and the significant decrease in its production expected after 2020 make us look for another, cheaper and more affordable hydrocarbon feedstock.

A number of processes proceed in the presence of catalytic systems with a molecular sieve structure (SAPO-34), as described:

in patent Union Carbide Corporation (USA) US 4440871;

in patents of the company UOP (USA) US 4849575; US 5095163; US 5191141; US 5,714,662; RU 2203875;

in Van Dijk Technology El patents. Email C (USA) RU 2198867; US 6,399,844;

in Exxon Mobil Chemical Patents, Inc. patents (United States) - US 6531639; US 6717023; US 6784330;

and in patent JGC Corporation (Japan) - US 6852897.

Closest to the claimed invention are a method of producing a catalyst for the synthesis of light olefins containing 2-4 carbon atoms, according to the patent US 6441262, which includes improving the properties of the catalyst molecular sieve based on silicoaluminophosphate - SAPO-34, SAPO-18, their metal-containing forms or mixtures (i.e., its modification) by mixing it with silica, and a method for synthesizing light olefins containing 2-4 carbon atoms by contacting an oxygenate feed, in particular methanol, dimethyl ether, with the catalyst obtained by this way.

A disadvantage of the known solution is that the methanol conversion is incomplete (98.2%), and the yield of C2-C4 olefins is 82%.

The objective of the invention is to ensure complete conversion of raw materials and increase the yield of C2-C4 olefins.

This problem is solved in that in the method for producing a catalyst for the synthesis of olefins containing from 2 to 4 carbon atoms, including modifying a catalyst based on silicoaluminophosphates with a silicon source, the silicon source is trimethylsiloxysilesesquioxane, the resulting catalyst contains from 0.1 to 10 wt.% Silicon, and the modification is carried out by impregnation by moisture capacity from a solution of a source of silicon or by impregnation from a solution of a source of silicon.

Molecular sieves of the SAPO-18 or SAPO-34 type, or molecular sieves containing their crystallized phases, are used as a catalyst based on silicoaluminophosphates.

This problem is also solved by the fact that in the method of synthesis of lower olefins containing from 2 to 4 carbon atoms, including the conversion of carbon-containing raw materials in the presence of a catalyst based on silicoaluminophosphates modified with a silicon source, a catalyst obtained by the specified method is used.

As a carbon-containing raw material, methanol or an aqueous solution thereof containing from 25 to 100% by weight of methanol or dimethyl ether DME or chloromethane is used.

The conversion is preferably carried out in the gas phase at 350-500 ° C, atmospheric pressure and a feed rate of 0.5-15 g / g hour.

The conversion is preferably carried out in the presence of a diluent gas.

Trimethylsiloxysilsesesquioxoxane is also called polycyclic octane.

The following examples illustrate the invention, but do not limit it.

Example 1 (comparative)

The catalyst, which is a silicoaluminophosphate type SAPO-18, synthesized by analogy with the method described in J. Chen, J. Meurig Thomas, P.A. Wright, R.P. Townsend "Silicoaluminophosphate number eighteen (SAPO-18): a new microporous solid acid catalyst" // "Catalysis Letter", 1994, No. 28, c.241-248, placed in a flow reactor, purged with nitrogen at 500 ° C for one hours, then reduce the temperature to 400 ° C and serves methanol at a rate of 2 g / g * hour at atmospheric pressure. At the outlet of the reactor ethylene is obtained with a yield of 35%, propylene - 40%, the total yield of olefinic hydrocarbons with the number of carbon atoms from 2 to 4 - 87%, at 100% methanol conversion. Comparison of the following examples with example 1, where they do not carry out the modification of silicoaluminophosphate, demonstrate the advantages of the proposed method for producing lower olefins. Process indicators are presented in table 1.

Example 2 (comparative)

The process is carried out as in example 1, the difference is that as a catalyst use silicoaluminophosphate type SAPO-34, synthesized by analogy with the method described in patent US 6696032 B2, publ. 02.24.2004. Comparison of the following examples with example 2, where the silicoaluminophosphate is not modified, demonstrate the advantages of the proposed method for producing lower olefins. Process indicators are presented in table 1.

Example 3 (comparative)

The process is carried out as in example 1, the difference is that silicoaluminophosphate containing

co-crystallized phases of the type SAPO-34 and SAPO-18, synthesized by analogy with the method described in application US 2005/0096214 A1, publ. 05/05/2005. The comparison of example 19 with example 3, where they do not carry out the modification of silicoaluminophosphate, demonstrate the advantages of the proposed method for producing lower olefins. Process indicators are presented in table 1.

Example 4

The catalyst, as in example 1, is placed in a flow reactor, purged with nitrogen at 500 ° C for one hour, then the temperature is reduced to 400 ° C and methanol is fed at a rate of 2 g / g * hour at atmospheric pressure. The catalyst used is silicoaluminophosphate type SAPO-18, modified by moisture-impregnation of a bone with a solution of trimethylsiloxysilesesesquioxane (PCS) in hexane. A comparison of the results with the prototype of example 1 illustrates the advantage in the yield of target olefin hydrocarbons having from 2 to 4 carbon atoms. Process indicators are presented in table 1.

Example 5

The process is carried out as in example 4, the difference is that the impregnation of the moisture capacity of a solution of trimethylsiloxysiloxysilsesquioxane in hexane is repeated. Process indicators are presented in table 1.

Example 6

The process is carried out as in example 4, the difference is that the impregnation in moisture capacity of a solution of trimethylsiloxysilsesesquioxoxane in hexane is carried out for the third time.

Example 7

The process is carried out as in example 4, the difference is that the impregnation of the moisture capacity of a solution of trimethylsiloxysilsesesquioxoxane in hexane is carried out for the fourth time. The process indicators are presented in table 1. Examples 4-7 illustrate the possibility of using PCS as a source of silicon, as well as varying the composition of the catalyst over a wide range.

Examples 4-7 illustrate the possibility of varying the composition of the catalyst containing silicon dioxide on silicoaluminophosphate SAPO-18, in a wide range.

Example 8

The process is carried out as in example 2, the difference is that the catalyst is used silicoaluminophosphate type SAPO-34, modified by the method of impregnation by moisture capacity with a solution of trimethylsiloxysilesesesquioxane in hexane, by analogy with example 4.

A comparison of the results with the prototype of example 2 illustrates the advantage in the yield of the target olefinic hydrocarbons having from 2 to 4 carbon atoms. Process indicators are presented in table 1.

Example 9

The process is carried out as in example 3, the difference is that silicoaluminophosphate containing

co-crystallized phases of the type SAPO-34 and SAPO-18, modified by the method of impregnation according to the moisture capacity of the solution

trimethylsiloxysilsesesquioxane in hexane. Comparison of the results with the prototype of example 3 illustrates the advantage in the yield of target olefin hydrocarbons having from 2 to 4 carbon atoms. Process indicators are presented in table 1.

Example 10

The process is carried out as in example 6, the difference is that the contacting of methanol and the catalyst is carried out at a temperature of 350 ° C. Process indicators are presented in table 1.

Example 11

The process is carried out as in example 6, the difference is that the contacting of methanol and the catalyst is carried out at a temperature of 450 ° C. Process indicators are presented in table 1.

Example 12

The process is carried out as in example 6, the difference is that the contacting of methanol and the catalyst is carried out at a temperature of 500 ° C. Process indicators are presented in table 1.

Example 13

The process is carried out as in example 6, the difference is that the composition of the feedstock fed to the catalyst is a solution containing 75 wt.% Methanol and 25 wt.% Water. Process indicators are presented in table 1.

Example 14

The process is carried out as in example 6, the difference is that the composition of the feedstock fed to the catalyst is a solution containing 50 wt.% Methanol and 50 wt.% Water. Process indicators are presented in table 1.

Example 15

The process is conducted as in example 6, the difference is that the composition of the feedstock fed to the catalyst is a solution containing 25 wt.% Methanol and 75 wt.% Water. Process indicators are presented in table 1.

Examples 13-15 illustrate the possibility of varying the composition of the feedstock to obtain the desired ratio of the yields of target olefinic hydrocarbons containing from 2 to 4 carbon atoms.

Example 16

The process is carried out as in example 6, the difference is that the feedstock fed to the catalyst is dimethyl ether. Process indicators are presented in table 1.

Example 17

The process is carried out as in example 6, the difference is that the feedstock fed to the catalyst is chloromethane. Process indicators are presented in table 1.

Thus, the use for the preparation of C2-C4 olefins of the catalyst obtained by the claimed method, allows for the complete conversion of carbon-containing raw materials and increase the yield of C2-C4 olefins.

Claims (10)

1. A method of producing a catalyst for the synthesis of olefins containing from 2 to 4 carbon atoms, comprising modifying a catalyst based on silicoaluminophosphates with a silicon source, characterized in that the silicon source is trimethylsiloxysilsesesquioxane, the resulting catalyst contains from 0.1 to 10 wt.% Silicon, and the modification carried out by impregnation by moisture capacity from a solution of a source of silicon or by impregnation from a solution of a source of silicon. 2. The method according to claim 1, characterized in that molecular sieves of the SAPO-18 or SAPO-34 type or molecular sieves containing their crystallized phases are used as a catalyst based on silicoaluminophosphates. 3. The method of synthesis of lower olefins containing from 2 to 4 carbon atoms, including the conversion of carbon-containing raw materials in the presence of a catalyst based on silicoaluminophosphates, a modified silicon source, characterized in that they use the catalyst obtained by the method according to claim 1. 4. The method according to claim 3, characterized in that molecular sieves of the SAPO-18 or SAPO-34 type, or molecular sieves containing their crystallized phases, are used as a catalyst based on silicoaluminophosphates. 5. The method according to claim 3, characterized in that methanol or an aqueous solution containing 25 to 100 wt.% Methanol, or DME dimethyl ether, or chloromethane is used as the carbon-containing raw material. 6. The method according to claim 3, characterized in that the said conversion is carried out in the gas phase at 350-500 ° C. 7. The method according to claim 3 or 6, characterized in that the said conversion is carried out at atmospheric pressure. 8. The method according to claim 3 or 6, characterized in that the said conversion is carried out at a feed rate of 0.5-15 g / g h. 9. The method according to claim 7, characterized in that the said conversion is carried out at a feed rate of 0.5-15 g / g h. 10. The method according to claim 3, characterized in that the said conversion is carried out in the presence of a diluent gas.