RU2737897C1 - Method of preparing a catalyst and a method of producing isopropyl benzene using said catalyst - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to a method of producing isopropylbenzene during alkylation of benzene with propylene at temperature of 170-230°C, pressure from atmospheric to 50 atm, molar ratio of benzene / propylene in the starting mixture of 4:1 to 10:1, weight feed rate of the initial mixture of 0.2 to 10 h^-1 using a catalyst based on zeolite Beta, prepared by contacting zeolite Beta with an ammonium nitrate solution for removing compounds sodium and translation of the zeolite to the hydrogen form, with the subsequent granulation step with a binder, drying and calcining the granules, wherein neolit Beta before granulation with the binder previously treated with a solution of a chelating agent, and then treated with superheated steam at temperature not higher than 550°C for at least 2 hours, sulfosalicylic acid, ethylenediaminetetraacetic acid, EDTA is used as chelating agent, sulpho-benzoic acid, 3-hydroxynaphthalene-1,4-disulphonic acid.

EFFECT: technical result consists in increasing duration of inter-regeneration range of catalyst.

1 cl, 5 ex

Description

The invention relates to catalysts and methods for their preparation for the processes of highly selective synthesis of alkylaromatic hydrocarbons, in particular isopropylbenzene, by alkylation of benzene with propylene. Isopropylbenzene (cumene) is a raw material in the production of phenol, acetone, α-methylstyrene.

Currently, large-scale industrial processes for the production of cumene, an important intermediate product in the production of phenol, acetone, and α-methylstyrene, are based on the alkylation of benzene with propylene in the presence of Friedel-Crafts catalysts or phosphoric acid on kieselguhr. The disadvantages of these processes (environmental pollution and severe corrosion of equipment) are devoid of solid acid catalysts, such as zeolites. However, the formation of cumene on zeolite catalysts is accompanied by a number of side reactions: alkylation to polyalkylbenzenes, isomerization of cumene to n-propylbenzene, the formation of toluene, ethylbenzene, and other alkyl derivatives, and finally, coke formation. The suppression of side reactions and the implementation of the selective alkylation of benzene into cumene would make it possible to most effectively use zeolites as a replacement for the currently used catalysts of this process.

Known catalyst for the synthesis of cumene, containing 65 wt.% Zeolite with the structure of ZSM-12 in the H-form and aluminum oxide 35 wt.%, And a method of its preparation [US 4393262, C07C63 / 34, 12.07.1983] by hydrothermal crystallization zeolite powder with the ZSM-12 structure, oxidative heat treatment of the powder in an air stream at a temperature of 400-500 ^o C, cation exchange of the calcined zeolite powder with a solution of ammonium chloride, granulation of decationized zeolite powder with aluminum oxide as a binder, followed by drying of the catalyst granules and their heat treatment in an air stream at a temperature of 500-550 ^o C. The catalyst allows the synthesis of cumene by alkylation of benzene with propylene at temperatures of 100 ^o C and above, pressure from atmospheric to 60 atm, molar ratio (benzene / propylene) in the initial mixture from 12: 1 to 1 : 1, the weight feed rate of the initial mixture at a pressure of 1 atm from 0.05 to 100 h ^-1 .

The disadvantage of an analogue catalyst based on zeolite ZSM-12 [US 4393262, C07C63 / 34, 12.07.1983] is a short run time (less than 300 h), as well as its low activity, as a result of which low conversions of both benzene and propylene are observed, even under conditions of high total pressure in the catalytic reactor and long contact time of the reaction mixture with the catalyst.

Known catalyst for the synthesis of cumene [EP 0432814, C07C2 / 66, 19.06.1991] is a powdered zeolite Beta (100 wt.%) In the H-form of aluminosilicate or boron-aluminosilicate compositions, which allows granulation with a binder material, and its method preparation [EP 0432814, C07C2 / 66, 19.06.1991] by hydrothermal crystallization of a zeolite powder with the Beta structure, oxidative heat treatment of the powder in an air stream at 550 ^o C, cation exchange of the calcined zeolite powder with an ammonium acetate solution and final heat treatment of the powder in an air stream at a temperature of 500-550 ^o C. An analogue catalyst [EP 0432814, C07C2 / 66, 19.06.1991] is used in the form of a powder under static conditions of the catalytic process and makes it possible to obtain cumene by alkylation of benzene with propylene at temperatures from 100 to 300 ^o C, pressure from 10 to 50 ata, molar ratio (benzene / propylene) in the initial mixture from 2: 1 to 30: 1, calculated weight rate and feeding the initial mixture from 0.1 to 200 h ^-1 . The disadvantage of an analogue catalyst based on zeolite Beta [EP 0432814, C07C2 / 66, 19.06.1991] is the short run time (up to 200 h), the need to work with zeolite powder in a batch mode, which complicates the catalyst regeneration stage and is not technologically advanced, and low catalyst activity, as a result of which a low conversion of benzene is observed even under conditions of high total pressure in the autoclave.

Known catalyst for the synthesis of cumene [US 4891458, C07C2 / 66, 02.01.1990] containing zeolite Beta in the H-form 80 wt.% And alumina 20 wt.%, And a method of its preparation [US 4891458, C07C2 / 66, 01/02/1990] by hydrothermal crystallization of zeolite powder with the Beta structure, oxidative heat treatment of the powder in an air stream at a temperature of 500-550 ^o C, cation exchange of the calcined zeolite powder with ammonium nitrate solution, granulation of decationized zeolite powder with aluminum oxide as a binder, followed by drying catalyst granules and their heat treatment in an air stream at a temperature of 500-550 ^o C. The catalyst allows the synthesis of cumene by alkylation of benzene with propylene at temperatures from 120 to 230 ^o C, pressure from 3.5 to 69 ata, molar ratio (benzene / propylene) in initial mixture from 4: 1 and higher, weight feed rate of the initial mixture from 0.5 to 50 h ^-1 . Some details of the technology of the alkylation process on this catalyst are also reflected in [US 5081323, C07C2 / 66, 14.01.1992]. The disadvantage of an analogue catalyst based on zeolite Beta [US 4891458, C07C2 / 66, 02.01.1990] is, although significantly longer than the previous ones, but insufficient for real technology, the duration of the run: 500 h, i.e. less than a month.

Closest to the proposed invention is a method for preparing a catalyst [RU 2097129, B01J29 / 70, C07C2 / 66, 11/27/1997], which solves the problem of increasing the duration of the continuous run of the catalyst in the process of cumene synthesis by alkylation of benzene with propylene while maintaining a high level and conversion of benzene, and the conversion of propylene, and the selectivity to the desired product. This is achieved by using a catalyst based on a zeolite with a Beta structure of the following composition, wt%: 66-72 zeolite Beta in the H-form, 22-24 silicon dioxide (as a binder), 4.1-11.5 phosphorus pentoxide. The alkylation reaction of benzene with propylene is carried out in a flow reactor at atmospheric pressure, a temperature of 200 ^{° C,} the molar ratio benzene / propylene of 5, with a weight rate of feed mixture of 0.3 hr ^-1.

The disadvantage of this catalyst is also the short duration of the interregeneration run of 1000 h.

The invention solves the problem of developing a method for preparing an effective catalyst for the highly selective synthesis of isopropylbenzene in the process of benzene alkylation with propylene.

The technical result is an increase in the duration of the interregeneration run of the catalyst during the synthesis of isopropylbenzene by alkylation of benzene with propylene.

The problem is solved by the proposed method for preparing the catalyst, as well as by the process of producing isopropylbenzene using this catalyst.

Beta zeolite, pretreated with solutions of organic or inorganic acids, granulated with aluminum oxide as a binder, is used as the acidic component of the catalyst. An essential distinguishing feature of the proposed method from the prototype is that the specified acid component used for the production of a porous catalyst, before the granulation stage, is preliminarily treated with a solution of a chelating agent selected from the series: sulfosalicylic acid, ethylenediaminetetraacetic acid (EDTA), sulfobenzoic acid, 3-hydroxynaphthalene -1,4-disulfonic acid, followed by - treatment with superheated steam at a temperature not higher than 550 ^{° C} for at least 2 hours.

Pretreatment with a solution of a chelating agent selected from the group of sulfosalicylic acid, EDTA, sulfobenzoic acid, 3-hydroxynaphthalene-1,4-disulfonic acid, and then - with superheated steam at a temperature not higher than 550 ^{° C} for at least 2 hours results:

firstly, to a decrease in the number of catalyst acid sites located mainly on the outer surface of zeolite Beta crystals, which are responsible for secondary cracking reactions and the formation of polyalkyl derivatives, practically without affecting acid sites in the bulk of zeolite crystals (selective dealumination), and, as a consequence, to improved selectivity;

secondly, to the removal of active sites of coke formation from the outer surface of the porous catalyst, and, as a consequence, to an increase in the duration of the catalyst run between regeneration.

The alkylation reaction of benzene with propylene is carried out in a flow reactor at a temperature of 170-230 ^o C, a pressure from atmospheric to 50 atm, a benzene / propylene molar ratio in the initial mixture from 4: 1 to 10: 1, a weight feed rate of the initial mixture from 0.2 to 10 h ^-1 .

This distinctive feature gives the catalyst new properties, as a result of which the goal is achieved - to increase the duration of the continuous run of the catalyst in the process of cumene synthesis by alkylation of benzene with propylene to 3500 h versus 1000 h in the prototype [RU 2097129, B01J29 / 70, C07C2 / 66, 27.11.1997 ] while maintaining a high level and conversion of benzene, and conversion of propylene, and selectivity for the target product (cumene).

The essence of the invention is illustrated by the following examples.

Example 1 (prototype).

At the 1st stage, the initial form of zeolite Beta is obtained by hydrothermal synthesis in an autoclave at 150-175 ^o C for 20-30 hours from a mixture containing silica gel, sodium aluminate, sodium hydroxide, tetraethylammonium hydroxide and water. To prepare the initial mixture, an alkaline solution is first prepared: 63 g of sodium aluminate, 63 g of sodium hydroxide and 1350 ml of 30% tetraethylammonium hydroxide in 5400 ml of water. The alkaline solution is added with stirring to 900 g of powdered silica gel. At the end of the hydrothermal synthesis, the powder of the initial form of zeolite Beta is filtered from the mother liquor, washed with water and dried at 105 ^o C.

At the 2nd stage, a decationized form of zeolite Beta is prepared. For this, the dry powder of the original form is calcined in an air stream at 500-550 ^o C for 5-8 hours to remove organic substances. The calcined powder is treated for 2-3 hours at 30-50 ^o C in a 10-fold weight amount of an aqueous 0.5 M ammonium nitrate solution to remove sodium compounds. At the end of the treatment, the decationized form of zeolite Beta (H-form) is filtered off, washed on a filter with water and dried at 105-110 ^o C.

At the 3rd stage, a paste is prepared for catalyst granulation. To do this, the mixer for pastes with continuous stirring is loaded in a certain ratio and in the specified sequence: decationized form of zeolite Beta, powdered silica gel and water. After homogenization for 1 hour, a paste of the following composition is obtained, wt%: zeolite Beta - 37-43, silicon dioxide - 8-13, water - 48.5-50.

At the 4th stage, the paste is passed with an extruder or a syringe through a die and a wet granular zeolite is obtained in the form of cylindrical cuttings with a diameter of up to 3 mm, a length of 3-5 mm, which is dried at 105-110 ^o C and calcined at 500-550 ^o C. Granules have the following composition, wt%: zeolite Beta –75, silicon dioxide - 25.

At the 5th final stage, the granular zeolite is treated with an equal volumetric aqueous solution of diammonium phosphate having a density in the range of 1.06-1.18 (20 ^o C). The treatment is carried out without stirring at a temperature of 20-30 ^o C for 10-12 hours. At the end of the impregnation, the excess solution is drained from the granules; the wet catalyst is dried at 105-110 ^° C and calcined at 500-550 ^° C.

The resulting catalyst is characterized by the content of phosphorus pentoxide in it in an amount of 4.1-11.5 wt.%, Introduced into the catalyst by impregnating the granular zeolite with an excess of aqueous ammonium phosphate solution, as well as the type of binder used, namely, silicon dioxide.

For the synthesis of isopropylbenzene by alkylation of benzene with propylene, 10 g of the obtained catalyst are loaded into a flow reactor. The process is carried out at atmospheric pressure, a temperature of 200 ^about C, a benzene / propylene molar ratio of 5, with a weight feed rate of the mixture equal to 0.3 h ^-1 . The catalyst is activated with air at 500 ^o C for about 1 hour, the operating temperature is set in the frontal catalyst bed, displacing the air with an inert gas. After turning off the inert gas supply, a mixture of benzene with propylene is fed into the reactor through the evaporator. The reaction products are collected in a separator and analyzed by gas-liquid chromatography. As characteristics of the catalyst activity, the conversion rates of benzene and propylene, as well as the selectivity (molar) for all reaction products, are calculated.

The change in these characteristics is used to determine the duration of the catalyst run between regeneration, which in this example is 1000 h.

Example 2.

The decationized form of zeolite Beta (H-form) is obtained analogously to steps 1 and 2 of example 1 (prototype). The resultant zeolite in the H form is subjected to selective dealumination 10% solution of sulfosalicylic acid under stirring at 90-95 ^{° C} for 2 hours. After the extraction treatment, the product was washed with distilled water until the washing water cleared until it reaches a pH in the range of from 5 to 8. The resulting decationized zeolite Beta powder is granulated with 25 wt.% Silicon oxide as a binder similar to steps 3 and 4 of example 1 (prototype).

Thereafter, the pellets were dried for 12 hours at ¹²⁰ ° C and treated with superheated steam for 2 hours at a temperature of 550 ° ^C.

The tests of the catalyst in the reaction of obtaining isopropylbenzene by alkylation of benzene with propylene are carried out in a flow reactor analogously to example 1 (prototype).

The duration of the regeneration run of the obtained catalyst is 3500 h.

Example 3.

The decationized form of zeolite Beta (H-form) is obtained analogously to steps 1 and 2 of example 1 (prototype). The resultant zeolite in the H form is subjected to selective dealumination 10% solution of EDTA with stirring at 90-95 ^{° C} for 2 hours. After the extraction treatment, the product was washed with distilled water until the wash water until Purified not reach a pH in the range of from 5 to 8. The rest of the catalyst preparation procedures are similar to example 2.

Catalyst tests in the reaction for producing isopropylbenzene the alkylation of benzene with propylene is carried out in a flow reactor analogously to example 1 (prototype).

The duration of the regeneration run of the obtained catalyst is 2650 h.

Example 4.

The decationized form of zeolite Beta (H-form) is obtained analogously to steps 1 and 2 of example 1 (prototype). The resultant zeolite in the H form is subjected to selective dealumination 10% solution sulfobenzoic acid under stirring at 90-95 ^{° C} for 2 hours. After the extraction treatment, the product was washed with distilled water until the washing water cleared until it reaches a pH in the range of from 5 to 8. The rest of the catalyst preparation procedures are similar to example 2.

Catalyst tests in the reaction for producing isopropylbenzene the alkylation of benzene with propylene is carried out in a flow reactor analogously to example 1 (prototype).

The duration of the regeneration run of the obtained catalyst is 3100 h.

Example 5.

The decationized form of zeolite Beta (H-form) is obtained analogously to steps 1 and 2 of example 1 (prototype). The resultant zeolite in the H form is subjected to selective dealumination 10% solution of 3-hydroxynaphthalene-1,4-disulfonic acid under stirring at 90-95 ^{° C} for 2 hours. After the extraction treatment, the product was washed with distilled water until the wash until purified the water will not reach a pH in the range from 5 to 8. The rest of the catalyst preparation procedures are similar to example 2.

Catalyst tests in the reaction for producing isopropylbenzene the alkylation of benzene with propylene is carried out in a flow reactor analogously to example 1 (prototype).

The duration of the regeneration run of the obtained catalyst is 3500 h.

Claims (1)

A method for producing isopropylbenzene in the process of alkylation of benzene with propylene at a temperature of 170-230 ^o C, a pressure from atmospheric to 50 atm, a benzene / propylene molar ratio in an initial mixture from 4: 1 to 10: 1, a weight feed rate of an initial mixture from 0.2 to 10 h ^-1 using a catalyst based on zeolite Beta prepared by contacting zeolite Beta with a solution of ammonium nitrate to remove sodium compounds and convert the zeolite into the hydrogen form, followed by granulation with a binder, drying and calcining the granules, moreover, zeolite Beta before granulation with a binder pre-treated with a solution of a chelating agent, and then treated with superheated steam at a temperature not higher than 550 ^{° C} for at least 2 hours, as a chelating agent is used sulfosalicylic acid, ethylenediaminetetraacetic acid, EDTA, sulfobenzoic acid, 3-hydroxynaphthalene-1,4- disulfonic acid.