RU2052388C1 - Method for reclaiming spent highly-acid cationite - Google Patents

Abstract

FIELD: separation of materials. SUBSTANCE: method involves treatment of solution with highly-acid cationites in NH $\genfrac{}{}{0ex}{}{\text{+}}{\text{4}}$ -form. Cationite is washed with desalinated water and reclaimed with an aqueous solution of acetate-formiate of ammonium or sodium produced from neutrilized sewage of dimethylterephthalate, concentration 0.55-1.50 g.equiv/l. The solution is treated with highly-acid cationite in Na⁺-form. The process is made cheaper due to the use of a cheaper reclaiming agent. When cationites are reclaimed by solutions of acetate-formiate of ammonium the process becomes cheaper by 10-10.3 times; when they are reclaimed with solutions of acetate-formiate of sodium, by 3.4-3.6 times. EFFECT: process technology is ecologically clean due to the use of sewage accompanying the production of dimethylterephthalate for preparing the solution of reclaimed catalyst. 7 dwg

Description

 The invention relates to methods for the separation of spent catalysts from solutions and can be used in the extraction of cobalt and manganese acetate formates from the residues of the production of carboxylic acids and their esters, in particular dimethyl terephthalate.

 A known method for the extraction of non-ferrous metals from sulfate solutions and pulps by sorption by sulfocathionites, for example KU-2, followed by regeneration [1] in accordance with which the regeneration of nickel and cobalt is carried out with a solution of calcium chloride.

 The disadvantage of this method is the need for an additional step of converting cobalt chloride to a cobalt salt of an organic acid.

A known method for the extraction of cobalt ions or cobalt and manganese ions from acetate solutions [2] comprising passing an acetic acid solution of metal acetates through strongly acidic cation exchanger KU-2-8hC in NH $\genfrac{}{}{0ex}{}{\text{+}}{\text{4}}$ -form and regeneration of the above cation exchange resin with a solution of ammonium acetate.

The closest in technical essence is the method of regeneration of spent strongly acidic cation exchange resin in the CO ²⁺ , Mn ²⁺ form when extracting cobalt and manganese ions from the resinous residue extract from the production of dimethyl terephthalate, including washing the cation exchange resin with demineralized water and treating it with a regenerating agent, sodium acetate, acetic acid solution 3]
The disadvantage of these methods is the need to use fresh acetic acid to obtain a solution of a regenerating agent.

 The purpose of the invention is to reduce the cost of the process by using a regenerating agent obtained on the basis of acidic water of dimethyl terephthalate production, as well as reducing the amount of wastewater.

This goal is achieved in that the regeneration of the spent strongly acidic cation exchanger sorption of cobalt and manganese ions is carried out: on strongly acid cation exchanger in NH $\genfrac{}{}{0ex}{}{\text{+}}{\text{4}}$ -form, cation exchange resin is washed with demineralized water, the regeneration of cobalt and manganese ions is carried out with an aqueous solution of ammonium acetate formate, obtained on the basis of wastewater from the production of dimethyl terephthalate; on the strongly acidic cation exchanger Na ⁺ form, the cation exchanger is washed with demineralized water, the regeneration of cobalt and manganese ions is carried out with an aqueous solution of sodium acetate formate, obtained on the basis of wastewater from the production of dimethyl terephthalate.

 When developing technological schemes based on the use of ion exchange, the main condition is the choice of a regenerating agent, since The main operating costs do not fall on the wear of ion exchangers and their loss, but on the regeneration and processing of the regenerate to the finished product.

 For the regeneration of cation exchangers, acid solutions or salt solutions are used. The use of one or another regenerating solution is determined by the scheme of processing the regenerator into finished products. The most common is the acid regeneration of cation exchangers, as a result of which the cation exchange resin is converted to the hydrogen form, which has an advantage in the sorption stage.

 If it is necessary to obtain a regenerate, which is a solution of acetate or formate, or cobalt acetate formate, the difficulty lies in the fact that strongly acid cation exchangers are practically not regenerated by solutions of acetic or formic acids, as well as their mixture.

 Obtaining solutions of cobalt acetate, formate or acetate formate at the stage of regeneration of strongly acidic cation exchanger is possible only as a result of the use of salt regeneration, i.e. the use of solutions of a metal acetate, formate or acetate formate as a regenerating agent, whose ion is less adsorbed than cobalt ion.

 As a regenerating agent, it is possible to use solutions of acetates, formates or acetate formates of alkali metals or ammonium.

 Acid wastewater from the production of dimethyl terephthalate is an aqueous solution of acetic and formic acids, methanol, and also contains small amounts of methyl acetate, methyl formate, paraxylene, methyl benzoate.

 The composition of acidic wastewater by the production of dimethyl terephthalate is shown in Table 1.

 A solution of ammonium acetate formate is obtained by neutralizing acetic and formic acids contained in acidic wastewater with aqueous ammonia.

 A solution of sodium acetate formate is obtained by neutralizing the acetic and formic acids contained in acidic wastewater with sodium hydroxide.

 The limits for changing the concentration of ammonium acetate formate and sodium acetate formate correspond to the limits for changing the total concentration of acetic and formic acids in wastewater.

When choosing the optimal mode of regeneration of ion exchangers, the main factors are:
concentration of a solution of a regenerating agent;
ionite regeneration duration;
the concentration of the target component in commodity regenerate;
the mass of the regenerating agent necessary to achieve a given degree of regeneration of the ion exchanger;
cost of a regenerating agent.

 According to the theory of equilibrium dynamics of sorption, the concentration of the target component in the commodity regenerate should increase with increasing concentration of the regenerating agent. The experimental possibility of the concentration of the target component on the concentration of the solution of the regenerating agent, given in a number of works on acid and salt regeneration of components, has a maximum at a concentration of the regenerating agent of 3-4 g · equiv / L. With an increase in the concentration of the latter, the concentration of the target component in the commodity regenerate decreases due to the deterioration of the kinetic parameters of the process as a result of a decrease in cation exchanger grains. In accordance with the above, the use of regenerating agents with a concentration of more than 2.5 g · equiv / l is not recommended.

 To reduce the cost of the mass of the regenerating agent to restore the exchange capacity of the cation exchange resin, it is necessary to use solutions of the regenerating agent of the lowest possible concentrations.

 However, the use of dilute solutions of a regenerating agent leads to the production of regenerates with a low concentration of the target component, thereby complicating their further use.

 The use for the regeneration of cation exchangers of solutions of acids and salts with a concentration of less than 0.5 g equiv / l is impractical.

 The dependence of the cost of the mass of the regenerating agent necessary to achieve a certain degree of regeneration on the concentration of the latter has a minimum and a wide concentration range close to the minimum.

 To reduce the duration of the stage of regeneration of cation exchanger, it is necessary to choose the concentration of the regenerating agent, close to the concentration that provides the minimum cost of the mass of the reagent.

 The final choice of the concentration of the regenerating agent is determined by the scheme of processing the regenerate into finished products and the technical and economic indicators of the process.

In the production of dimethyl terephthalate, solutions of cobalt and manganese acetates and solutions of cobalt and manganese acetate formates are used as a catalyst. The best option is the regeneration of KU-2-8hC cation exchanger with a solution of ammonium acetate formate or a sodium acetate formate solution having a concentration of 1.5 g equiv / l, while the highest concentration of Co ²⁺ , Mn ^{2+ ions} in the commodity regenerate is obtained.

In addition, the concentration of Co ²⁺ , Mn ^{2+ ions} in the commercial reagent during the regeneration of KU-2-8hC cation exchanger with the above solutions corresponds to their concentration in the solution of the para-xylene oxidation catalyst provided for by the technological regulations for the production of dimethyl terephthalate.

The composition of acidic wastewater does not always allow to obtain a concentration of a regenerating agent equal to 1.5 g equiv / l. For this reason, Table 2-3 shows other concentrations of the regenerating agent. The proposed technical solution consists in the selection of regenerating agents for the regeneration of the strongly acidic cation exchanger KU-2-8chC Co ²⁺ , Mn ²⁺ form and in the preparation of this agent as a result of neutralization of acidic wastewater from the production of dimethyl terephthalate.

 Traditionally, for the regeneration of strongly acidic cation exchangers in the form of heavy metal ions, solutions of strong mineral acids are used: sulfuric, hydrochloric, nitric. Accordingly, commodity regenerate is obtained in the form of a solution of metal chloride, sulfate or nitrate.

A solution of acetic or formic acids, or mixtures thereof, strongly acidic cation exchanger KU-2-8hC in Co ²⁺ or Co ²⁺ , Mn ²⁺ form does not regenerate. Acid wastewater from the production of dimethyl terephthalate also does not regenerate the above cation exchange resin in the Co ²⁺ or Co ²⁺ , Mn ²⁺ form.

 Additional regenerating agents have been selected that make it possible to obtain commercial regenerate in the form of a solution of cobalt and manganese acetate formates.

 The cheaper process is a consequence of the selection of regenerating agents that meet the requirements of the technology for the production of dimethyl terephthalate and obtained on the basis of waste products of dimethyl terephthalate.

 The economic effect per 1 liter of cation exchanger is the ratio of the costs of cation exchanger regeneration with a solution of ammonium acetate to the costs of cation exchanger regeneration with a solution of ammonium acetate or the ratio of the costs of cation exchanger regeneration with a solution of sodium acetate to the costs of cation exchanger regeneration with a sodium acetate formate solution.

PRI me R 1. Through a column with a diameter of 0.025 m, filled with 136 ml of strongly acidic cation exchanger KU-2-8chS in Co ²⁺ , Mn ²⁺ form containing 406.7 mg · equiv. Co ²⁺ and 38.3 mg At room temperature, Mn ^{2+ is} passed through a regenerating solution of ammonium acetate formate having a concentration of 1.5 g eq / L, obtained by neutralizing the acetic and formic acids contained in acidic wastewater with aqueous NH ₃ .

During the regeneration of cation exchanger, three fractions are distinguished:
the first fraction (reverse regenerate) in an amount of 130 ml with a concentration of cobalt and manganese ions of less than 0.03 g · equiv / l;
the second fraction (commercial regenerate) in an amount of 615 ml with a concentration of cobalt and manganese ions of 0.590 g · equiv / l;
the third fraction (reverse regenerate) in an amount of 980 ml with a concentration of cobalt and manganese ions of less than 0.07 g · equiv / L.

 The first and third fractions (reverse regenerates) are combined and used in the next regeneration as an additive to the solution of ammonium acetate formate.

 The results obtained in the following examples are presented in table.2-5.

PRI me R 2. Example 1 is repeated with the difference that the regeneration of cation exchanger KU-2-8chS in the Co ²⁺ , Mn ²⁺ form.

PRI me R 3. Repeat example 1 with the difference that the regeneration of a sample of cation exchanger KU-1 in the Co ²⁺ form.

PRI me R 4. Repeat example 1 with the difference that the regeneration of a sample of cation exchanger KU-1 in the Co ²⁺ , Mn ²⁺ form.

 PRI me R 5. Repeat examples 1,2,3,4 with the difference that in the amount of regenerating agent use a solution of sodium acetate formate.

Claims (1)

METHOD FOR REGENERATION OF SPENT strong-acid cation in Co ^{2 +} - ² MP ⁺ form in the manufacture of dimethyl terephthalate comprising washing the cation exchanger with demineralised water and regenerating processing agent, characterized in that as regenerant an aqueous solution of ammonium formate or sodium acetate concentration of 0 , 55 - 1.5 g-equiv / l, obtained after neutralization of acetic and formic acids contained in the wastewater of dimethyl terephthalate production.

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