RU2818597C1 - Continuous method of producing sulphocationites for catalytic processes based on copolymers of styrene with divinylbenzene and acrylonitrile - Google Patents

Abstract

FIELD: chemical or physical processes.

SUBSTANCE: invention relates to production of sulphocationites. Disclosed is a continuous method of producing sulphocationites for catalytic processes based on ternary copolymers of styrene, divinylbenzene and acrylonitrile by swelling in dichloroethane and their subsequent sulphonation in a continuous action plant, characterized by that the copolymer sulphonation process is carried out in a cascade-type three-section sulphurizer and made with enameled protection of working surfaces, and copolymers used are polydisperse copolymers of gel and porous structure.

EFFECT: disclosed method enables to use a fraction of less than 250 mcm of a copolymer of a gel structure and a fraction of less than 500 mcm of a copolymer of a porous structure.

1 cl, 1 tbl, 3 ex

Description

The invention relates to the production of sulfonic cation exchangers, which are used in chemical technologies as catalysts (“Catalysis by ion exchangers”, N.G. Polyansky, M. Khim., 1973). The presence of a catalyst in a chemical process creates, in addition to the necessary beneficial effect, a number of technological difficulties. The main ones are the need to remove the catalyst from the reaction mass, the possibility of equipment corrosion, and the danger of environmental pollution with products resulting from the neutralization of the catalyst. Sometimes the loss of substances used as a catalyst can be significant.

If an appropriate ion exchanger (sulfocation exchanger) is used as a catalyst, then all the above complications disappear. In this case, the catalytic active particle is fixed to the polymer matrix with sufficiently strong bonds and does not escape into the volume. The reaction catalyzed by it occurs on the surface of the polymer matrix, on which the reacting substances are sorbed and from which the reacting substances are desorbed, and from which the reaction products are desorbed, therefore the latter do not contain a catalyst and do not need to be purified from it. Naturally, since the catalyst is not lost, it can be reused, which makes it easy to organize continuous catalytic processes. Such catalysts in the chemical industry include both shaped and unshaped catalysts obtained from copolymers of styrene and divinylbenzene by sulfonation. So, in a number of patents (2258562 C2 in 01 J 31/10 J 37/04 37/08, 2493911 C1 B01J 31/10 B01J 37/04 B01J 37/08 2006/01, 2650502 B01J 31/10 B01J 37/00 C07C 31/12 2006.01) noted industrial methods for the production and use of molded catalysts based on sulfonated copolymers of styrene and divinylbenzene for the process of isobutylene hydration. The same molded catalysts are also used on an industrial scale (2307823С1 С07С 31/12 2006.01 С07С 29/04 2006.01, 2507190 С07С 32/12 С07С 29/04 2006.01) for the process of dehydration of tert-butyl alcohol to obtain high-purity isobutylene for the polymer stage ization in butyl rubber. Due to the specific quality of raw materials, sulfonic cation exchangers operate in the established industrial installations for one to two years. Their poisoning is observed, which leads to a decrease in productivity. Therefore, annual replacement of the catalyst is necessary.

As a base product in industry for the production of sulfonic cation exchangers and anion exchangers for water treatment, a fraction of 0.250-0.600 mm of a polydisperse copolymer of styrene and divinylbenzene with a gel structure with different cross-linking is used (RF patent 2050367C1 C08F8/36 C08J5/20 C08F212/14 C08F212/36). But when producing a polydisperse copolymer by suspension copolymerization, the granule size ranges from 0.050 to 1000 mm. After separation, by sieving the marketable (0.250-0.600 mm) fraction, a small (not standard) fraction of the copolymer remained, which was subject to burial. In order to expand the base of raw materials and utilize the fraction of styrene copolymer with divinylbenzene less than 250 microns, it is proposed to carry out the process of sulfonation of this fraction and obtain a sulfonic cation exchanger for catalytic processes.

The closest in technical essence to the proposed method is the method by which sulfonic cation exchanger (for water treatment) is produced using continuous technology (RF patent 2085561 C1 C08J5/20, C08F8/36, C08F212/08, C08F212/36, C08F220/14). The difference of the proposed invention is the following: the starting material is used as a ternary copolymer of styrene, divinylbenzene and acrylonitrile with a gel structure in the ratio of the starting monomers (87.1-90, 2: 4.0-7.8: 3.1-5.3) , and a ternary copolymer of styrene, divinylbenzene and acrylonitrile with a porous structure in the ratio (83.2-86.2: 10.1-12.8: 3.1-5.3). The polydisperse composition of copolymers for a gel structure is 50 - 250 microns, for a porous structure - 50 - 1000 microns. On the technical side, the difference is that the sulfonation process is carried out in a continuous mode in a cascade of enameled reactors, and not in a screw-type sulfurizer, which is made of special grades of steel. The use of enameled equipment allows us to solve problems of corrosion and equipment repair.

The process according to the proposed method is carried out by the following technological operations. The original copolymer and dichloroethane (swelling agent) with a given productivity are continuously fed into a screw-type swelling unit. The duration of the copolymer processing process is from 30 to 50 minutes. The swollen copolymer from the swelling agent, together with the sulfonating mixture, enters the first section of the sulfurator. The sulfurator sections are arranged in stages in such a way that the mass moves by gravity from the first to the third section, then to the discharge column of the hydration process. Sequentially passing through sections, the copolymer is subjected to sulfonation until a given static exchange capacity is reached, with simultaneous distillation of dichloroethane from the reaction mass. Since the sulfonation process is carried out under a slight vacuum, dichloroethane vapor, together with sulfuric acid vapor from the sulfurator, is sent to the refrigerator. The level in the sulfurator sections is determined by the position of the overflow pipes. The resulting sulfonic cation exchanger (sulfomass) flows by gravity from the third section into the loading column, where it is cooled by cold water supplied to the jacket, and then flows to hydration (the process of washing off sulfuric acid).

Example No. 1. Gel copolymer of styrene with divinylbenzene and acrylonitrile with a specific volume of 2.5 ml/g, with a load of 150 kg/hour and dichloroethane with a load of 42 kg/hour are continuously fed into the swelling screw. After passing through the apparatus, the swollen copolymer enters the first section of the sulfurator. At the same time, a sulfonation mixture with a sulfuric acid concentration of 93.5 - 97.5% is continuously dosed into the first section at a mass ratio of sulfuric acid: copolymer - 6: 1. The sulfonation temperature in the first section is 90 ° C, in the second and third sections 104 ° C. The duration of stay and contact with sulfuric acid is 80 minutes. The resulting sulfonic cation exchanger, together with excess sulfuric acid from the sulfurator, is continuously sent to two-stage hydration, carried out according to a known method. The output from the installation is 440-470 kg per hour of commercial product. Analyzes of the physicochemical properties and catalytic activity of the resulting sulfonic cation exchanger were studied using known methods and are shown in Table No. 1.

Example No. 2. Sulfonic cation exchanger is obtained according to example No. 1, with the difference that the starting raw material is a gel ternary copolymer of styrene, divinylbenzene and acrylonitrile with a specific volume of 4.0 ml/g. The ratio is dichloroethane copolymer -1: 0.45. The swollen copolymer is fed into the first section of the sulfurator with a load of 150 kg/hour and the sulfurating mixture at a mass ratio of sulfuric acid: copolymer - 7.5: 1. The residence time of the copolymer in the sulfurator is 70 minutes. The output from the installation is 520-560 kg/hour of commercial product. Analyzes of the physicochemical properties and catalytic activity of the resulting sulfonic cation exchanger are given in Table No. 1.

Example No. 3. Sulfonic cation exchanger is obtained according to example No. 1, with the difference that the starting raw material is a porous ternary copolymer of styrene, divinylbenzene and acrylonitrile with a specific volume of 4.5 ml/g. The ratio of copolymer: dichloroethane is 1: 0.6. The first section of the sulfurator is fed with a swollen copolymer with a load of 150 kg/hour and a sulfonating mixture at a mass ratio of sulfuric acid: copolymer 7.7: 1.0; Duration of residence and contact with sulfuric acid of the copolymer is 80 minutes. The sulfonation temperature in the first section is 90 °C, in the second and third sections 105 °C. The duration of stay in the sulfurizer and contact with sulfuric acid is 80 minutes. From the sulfurator, the sulfomass continuously flows into the hydrator of the installation. The output is 500-540 kg/hour of commercial product. Analyzes of the physicochemical properties and catalytic activity of the resulting sulfonic cation exchanger are given in Table No. 1.

Table No. 1. Physicochemical and catalytic properties of the obtained sulfonic cation exchangers The name of indicators Example #1 Example No. 2 Example No. 3 Total static exchange capacity, mEq/g 5.0 5.82 5.2 Moisture contents, % 52.6 67.6 69.8 Specific volume, cm ³ /g 2.6 4.8 4.4 Free sulfuric acid, % 0.20 0.1 0.1 Catalytic activity for the decomposition of tert-butyl alcohol 80.0 85.5 98.0

Claims (2)

1. A continuous method for producing sulfonic cation exchangers for catalytic processes based on ternary copolymers of styrene, divinylbenzene and acrylonitrile by swelling in dichloroethane and their subsequent sulfonation in a continuous installation, characterized in that the process of sulfonation of the copolymer is carried out in a three-section cascade-type sulfurator, made with enameled worker protection surfaces, and polydisperse copolymers with a gel and porous structure are used as copolymers. 2. The method according to claim 1, characterized in that the sulfonated polydisperse copolymers have a fraction of 50-250 microns of gel structure and 50-1000 microns of porous structure.