Bipolar membrane electrolysis method for preparing carbon monoxide by electrolyzing carbon dioxide in organic electrolyte and simultaneously producing chlorine and metal hydroxide as byproducts

Abstract

The invention relates to a bipolar membrane electrolysis method for preparing carbon monoxide by electrolyzing carbon dioxide in an organic electrolyte and simultaneously producing chlorine and metal hydroxide as byproducts, and belongs to the technical field of phosgene chemical industry. The electrolytic tank is divided into a cathode chamber, a middle chamber and an anode chamber by a bipolar membrane and a cation exchange membrane to form a three-compartment electrolytic tank; wherein the electrolyte in the cathode chamber is an organic composite electrolyte in which a large amount of carbon dioxide is dissolved, the electrolyte in the middle chamber is a metal hydroxide aqueous solution, and the electrolyte in the anode chamber is a metal chloride aqueous solution. In the electrolytic reaction process, carbon monoxide is generated on the cathode, chlorine is generated on the anode, and the content of metal hydroxide in the middle chamber is increased. The method can synchronously produce carbon monoxide, chlorine and metal hydroxide under the conditions of normal temperature and normal pressure. The method has the advantages of short process flow, simple operation method, low production cost, small occupied area of equipment, easiness in starting and stopping, greenness, no pollution and the like.

Description

technical field [0001] The invention relates to a bipolar membrane electrolysis method for producing carbon monoxide by electrolyzing carbon dioxide in an organic electrolytic solution and simultaneously producing chlorine gas and metal hydroxide, which belongs to the technical field of phosgene chemical industry. Background technique [0002] Phosgene is an important acylating agent, which can be used in the preparation of high value-added products such as medicines, pesticides, and dyes. At present, the industry mainly uses carbon monoxide and chlorine as raw materials to produce phosgene (CO+Cl 2 =COCl 2 ), the required carbon monoxide comes from the coal-to-gas process, and the required chlorine gas comes from the chlor-alkali process. This method has the disadvantages of long process flow, large equipment footprint, complicated operation methods, and high production costs. [0003] The electroreduction of carbon dioxide to carbon monoxide and the synthesis of downstr...

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Problems solved by technology

This method has a research history of more than 100 years, and it has not yet realized industrial application. The main problems are: first, carbon dioxide is a non-polar molecule, and its solubility in aqueous solution is very small, only 0.033mol / L in the standard state, resulting in The current density of the cathodic reaction is too low; second, when electrolyzing carbon dioxide in an aqueous solution to produce carbon monoxide, in order to improve the conductivity of the electrolyte, it is necessary to add an inorganic supporting electrolyte to the electrolyte, which inevitably brings some inorganic impurities into the In the electrolyte, some of the impurities undergo electrodeposition reactions on the surface of the cathode, forming surface active sites with low hydrogen evolution overpotentials, resulting in an accelerated hydrogen evolution reaction, and also a decrease in the electrocatalytic activity of the electrode material for the carbon dioxide electroreduction reaction; third, When electrolyzing carbon dioxide in aqueous solution to produce carbon monoxide, due to the specific electrode / electrolyte interface environment, a small amount of carbon dioxide undergoes deep reduction to form amorphous carbon, which adheres to the surface of the cathode, resulting in electrode poisoning [Y. Hori. Electrochimica Acta 50 (2005) 5354 -5369], the current efficiency of generating carbon monoxide is rapidly reduced to zero; the 4th, the reaction of carbon monoxide produced by electrolysis of carbon dioxide, its cathode reaction product is carbon monoxide, and the anode reaction product is oxygen, because carbon monoxide can be made by coal gas method, oxygen can be separated by air The production cost of the latter two methods is very low, which leads to the high production cost of electrolyzing carbon dioxide to carbon monoxide, which is not economically feasible.

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