SU847928A3 - Method of producing sodium or potassium carbonate - Google Patents

Description

one

The invention relates to electrochemical production and can be used to produce low carbonation sodium or potassium carbonates, chloride.

A known method of producing sodium or potassium carbonate by chlo-electrolysis. the readout of the corresponding metal in the electrolyzer, separated by a non-flowing cation-exchange membrane into the anode and cathode space, with carbon dioxide fed into the cathode space tl.

In this method, a cation-exchange membrane based on a copoly measure of styrene and divinylbenzene is used, and the current density is maintained at 0.015-0.12 A /

cm

The disadvantage of this method is the high content of chloride in the semi-. carbonate, which is equal to an eye, is 0.2% in terms of solid product,

The purpose of the invention is to reduce the content of chloride in the resulting product.

The goal is achieved by the fact that, according to the method of producing sodium carbonate, elikali by electrolysis of the corresponding metal chloride in 30

the electrolytic cell, separated by a non-flowing cation-exchange membrane into the anode and cathode spaces, with carbon dioxide fed into the cathode space, a 0.05-0.2 mm thick film made of a copolymer containing a repeat cTpj7KTypffiJe film with a membrane thickness is used as the membrane

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where R is the group R-CF-CF ,, -0-CFY-C-a, where ft and Y is fluorine or-trifluoromethyl A is hydrogen, sodium or potassium;

p - O or 1,

with an equivalent weight of 1100-1300 and electrolysis is carried out at a current density of 0, A / cm11.

Example 1. Electrolysis is carried out in an electrolyzer containing an anode 5 cm in diameter, made of a titanium lattice coated with a mixture of titanium and ruthenium oxides in a molar ratio of 1: 1. A cathode of 5 cm in diameter is made as a stainless steel plate. A membrane in the form of a film with a thickness of 0.18 mm. To increase the mechanical strength, it is applied to tetrafluoroethylene fabric. In the electrolyzer, the distance between -cJp- d-pi b-UFt- "iF-o-dF | anode space is 335 cm and the cathode space is 195 cm. The electrolyzer is equipped with tubes for brine, carbon dioxide and for discharge electrolysis products. An aqueous solution of sodium chloride concentration of 225 g / l is used as the initial electrolyte, the anolyte contains 0.26 cm of 85% phosphoric acid and has a pH of 2.0. In the cathode space of the cell serves 12.4 water. The results of the experiments are given in table. 1. In experiments 3.4 and 9, electrolysis was conducted at a current density of 0.32 A / cm, and in other experiments at a current density of 0.96 A / cm, Example 2. The procedure was carried out under the same conditions as the difference that the distance between the anode cm and the membrane is 0.24 cm, the thickness of the membrane is 0.09 mm, the equivalent weight of the copolymer is 1-100, the amount of aqueous solution of hlc of emitted potassium fed into the anode space of the electrolyzer is 4, The measurement results are shown in Table. 2. Experience 1: 1-7 current density is 0.32 A / cm, in experiment 80, 48 A / cm f in experiment 9-0.64 experience 10-0.8 A / cm. Froze The process is carried out under the conditions of experiment 3 of Example 1, with the difference that the process is carried out at a current density of 0.16 A / ck /. The target product contains 0.32 g / l potassium chloride, the current output is 90.2%. EXAMPLE 4 The process is carried out under the conditions of Experiment 3 of Example 1, with the difference that the current density is maintained at 1.16 A / cm. The target product contains 0.008 g / l of potassium chloride and the current efficiency is 90.7%. Example The process is carried out under the conditions of Example 3 of Example 1, with the difference that a copolymer with an equivalent weight of 1300 in the form of a film with a thickness of 0.05 mm containing repeating is used as the membrane. structural units of the indicated formulas where R is fluorine, Y is trifluoromethyl, Anatrium, and n is 1. The target product contains O, 35 g / l of potassium chloride, and the current efficiency is 91.5%. the membrane and the anode is 0, b2 cm, between the membrane and the cathode - 0.31 cm. The copolymer from which the membrane is made has an equivalent weight of 1200 and contains repeated structural units of the formulas ", Example 6 in the conditions of experiment 3 of example 1, with the difference that a copolymer with an equivalent weight of 1200 is used in the form of a membrane with a film thickness of 0.2 mm, containing repeating structural units of the formulas indicated, where R is trifluoromethyl, Y is fluorine, And potassium and p- 1. The target product contains 0.29 g / l of potassium chloride, the current output is 91.8%. EXAMPLE 7 The process was repeated under the conditions of Test 3 of Example 1, with the difference that a copolymer with an equivalent weight of 120 Q in the form of a film 0.1 mm thick containing repeating structural units of the indicated formulas where n is O, and A is hydrogen. The target product contains 0.42 g / l of chloride, the current efficiency is 90.6%. Example8. The process is carried out under the conditions of Example 3 of Example 1, with the difference that the anolyte is a sodium chloride solution of a concentration of 225 g / l, and in membrane A it means hydrogen. The content of sodium chloride in the target product is 0.4 g / l, the current efficiency is 94.7%, the sodium carbonate yield is 90.2%. Example 94 The process was carried out under the CONDITIONS of test 1 of example 2, with the difference that acholite is a solution of sodium chloride at a concentration of 225 g / l, and in membrane A it is sodium. The content of sodium chloride in the target product is 0.3 g / l, the current efficiency is 93.9%, and the sodium carbonate yield is 90.5%. When implementing the proposed method, the content of chloride in carbonate is lower than the known (i.e. less than 0.2 wt.% Based on 100% product) “When the thickness of the membrane is less than 0.05 mm, the equivalent weight of the membrane is less than 1100 and the density current below 0.16 A / cm, the carbonate chloride content increases substantially to the level of a known method. An increase in membrane thickness is higher than 0.2 MM, I current density is higher than 1.16 A / cm, and an equivalent weight of membrane over 1300 causes a sharp increase in voltage on the electrolyzer and makes the process unsuitable for practical realization.

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Claims (1)

cm. I Formula of the invention of obtaining sodium or potassium carbonate by the electrolysis of chloride of the corresponding metal in an electrolyzer divided by a non-flowing cation-exchange membrane into the anode and cathode space, with carbon dioxide fed into the cathode space, characterized in that, in order to reduce the chloride content in the resulting product, As a membrane, a film with a thickness of 0.050.2 mm from a copolymer containing repeating structural units of the formulas - is used. : p CFj - OjA, where r is a group R-CP-CPd-O-CFY-CF-O-, where R and Y are fluoro or trifluoromethyl; d - hydrogen, sodium or cal117 p-O or 1, with an equivalent weight of 1100-1200 and electrolysis is carried out at a current density of 0.16-1.16 A / cm. Priority from 22.01.75 is given to the method in which A is hydrogen, Priority from 21.07.76 is given to 5tioco6y, in which A is sodium or potassium .. sources of information taken into account during the examination 1. Chem-Techn. 23, 10, s. 607, 1961.