SU751809A1 - Method of producing anion exchange resins - Google Patents

Description

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The invention relates to methods for producing ion exchange sorbents, in particular, to methods for producing anion exchange resins based on copolymers of styrene and divinylbenzene.

Methods are known for producing anion exchangers by aminating chloromethylated styrene and divinylbenzene copolymers with various amines 1. Chloromethylpolymers are treated with amines o or their solutions. Water, syrty, aromatic hydrocarbons, chlorinated hydrocarbons, aieton, dioxane, dimethylformamide, dimvgylsulfoxide, acetonitrile are used as solvents. The resulting aionite is separated from aminying, its composition, conditioned with Kiiclot and washed with water.

Successful carrying out the amination reaction is ensured only under conditions of 20 uniform swelling of the polymer matrix at all stages of transformation during the transition from a hydrophobic chloromethylium copolymer to a silionic anion exchange resin swelling in water. Only in this case can a good transport of the ammonia solution to the reaction centers inside the chloromethylated copolymer granule be ensured, the rate and completeness of the conversion of the chloromethyl groups into ammonia-30

groups, and high sorozponnye and Proof qualities of sorbents.

In the known methods, the condition of uniformity of the polymer matrix is not met, since the applied aminating protruding compounds affect the starting chloromethylium copolymer and the resulting anioite, causing swelling of one of them and deposition (i.e., compaction) of the other. Amines and their solutions in aromatic hydrocarbons, acetone, dimethyl form amide, dimethyl sulfoxide, acetyiitrile and chlorinated hydrocarbons cause swelling of the chloromethylated copolymer and precipitate aiooiite, in aqueous and alcoholic solutions of amines chloromethylene, the copolymer does not swell, and the sample will sweeten, and the sample will sweeten, and the sample and chlorinated solutions of amines will not swell.

These properties of aminating solutions adversely affect the flow of the ammonia reaction and the properties of the resulting sorbents: compaction of the polymer during the amination process makes it difficult for the ammonia solution to penetrate deep into the chlorine-resin granule, impairs the kinetics of the process and decreases the degree of amine synthesis. The presence of areas of different density (swollen and non-swollen layers in the granule of chloromethylated

copolymer at various stages of amnprovany) causes defects in granules, large changes in the volume of the polymer matrix during the transition from chloromethylated copolymer to anion exchangers and from organic medium to water when conditioned anion exchangers (2-4 times), and especially the alternation of processes swelling - compression - swelling matrix violate the integrity of l impair the mechanical strength of anopit.

A decrease in the amplitude of the fluctuation of the volumes of the granule and its individual sections at various stages and in the process is achieved by reducing the chlorine content in the chloromethylated soiolimeter to 14-16%, which leads to a decrease in the exchange capacity of the anion exchange resin. According to the known methods, it is practically impossible to obtain strong sorbents with an increased exchange capacity and eliminate losses during synthesis as a result of osmotic destruction of the granules.

The use of concentrated solutions of amines 2 in the known methods, associated with the need to increase the rate of amination, makes it difficult to turn and dispose of used solutions.

There is also known a method for the preparation of anion exchangers by amination of chloromethyl phosphate copolymers of ethnol and diviylbenzene with solutions of amines in methylal 3.

Methyl.ch and methyl solutions of amnnov cause swelling of the chloromethylated copolymer and aionite, however, the condition of uniformity of matrix swelling in the amination process is not fully fulfilled, as the swelling – compression – swelling cycles alternate more than pure methylale. This affects the mechanical strength of the sorbents. Pure methylal is not suitable for use as a solvent of tertiary amines, since it decomposes in its presence, forming paraforms, which complicate the amination process, worsening the kinetics and reducing the degree of tenseness.

The aim of the invention is to simplify the technology of nitration, to intensify the necroses, and to improve the quality of anion exchangers.

This goal is achieved by aminirovanie chloromethylated copolymers of styrene and divipylbenzene with solutions of amines, in which a solvent is a mixture of methylal and methanol with a volume ratio of methanol-methylal equal to 1: 3-15.

The addition of methanol prevents the decomposition of methylal and stabilizes methyl solutions of tertiary amines. The swelling capacity of chloromethyl-irovine co-polymers in the aminating mixture of ammonia-methylal-methanol is slightly less than in pure amine, methylale or methyl solutions of amines, but swelling

Anion exchangers much more. By this, compression of the matrix polymer during the formation of the anion exchanger is prevented and its volume increases smoothly during the transition from the chloromethyl sonomer to the conditioned anion exchanger.

The method is carried out by ampirovanizing chloromethylated copolymers with mixtures of} 1-methylal-methanol at 2 () C and above, at atmospheric pressure and at an increased pressure of 50–150 g / l amine concentration. The volume ratio of methanol-methylal should be in the range of 1: 3-15. This ratio of solvents (depending on the nature of the amine) ensures uniformity of the matrix swelling and prevents the decomposition of methylal by tertiary amines.

Example 1. 150 kg / h are simultaneously supplied to the continuous operation apparatus.

chloromethylated copolymer with 3.5% crosslinking and 21.5% chlorine in a mixture of 20 liters of methanol and 220 liters of methylal and a solution of pyridine of the following composition: 60 kg iridium, 40 liters of methanol and 85 liters of methylal. The resin is kept in the apparatus for 12 hours at a steady-state concentration of pyridine in the head of the apparatus 150 g / l, then the anion exchanger that has formed is washed with a 3% solution of ChCl and water in the system of the washing columns. The content of unreacted pyridium in the mother liquor was 65-70 g / l. The AMP anion exchanger obtained had a C1-ion exchange capacity of 3.6 mEq / g, a mechanical strength of 98.3%.

Example 2. 100 g of a chloromethylated copolymer with 4% crosslinking and 20.4% chlorine and 300 ml of a solution of 33.9 g of trimethylamine, 41.5 ml of methanol and 207.5 ml of methylal are charged to the reactor. Reactionary

the mixture is kept at 20-25 ° C for 8 hours, then anion exchange resin AM. unloaded, washed with U% HC1 and water. The content of trpmethylamine in the mother liquor was 2.1 g / l. Annonit AM had an exchange capacity but a C1-ion of 3.8 mg-eq / g, a mechanical strength of 99, G%.

In tab. 1 shows the technological conditions of the amination process according to the known and proposed method.

In tab. 2 compares the properties of anion exchangers obtained according to known and proposed methods.

Thus, the proposed method intensifies the process of obtaining an anioniton, increasing by 2 times the rate of amination and by 1.1 -1.8 times the degree of conversion of chloromethyl groups, allows the use of low concentrated solutions of amines, rather than

simplified disposal of waste peaTable I

environmental issues are resolved; allows to improve the quality of sorbents, increasing by 1.2-1.3 times the exchange capacity and mechanical strength.

Claims (3)

1 TO. M. Saldadze et al. Ion-exchanging high-molecular compounds, M., Goskhimizdat, 1960, p. 81. 2. USSR author's certificate number 309019, cl. C 08F 226/02, 1971. 3. Author's certificate USSR № 308026, cl. C 08F 8/32, 1970 (prototype).