Method for controlling cathode potential in electrochemical hydrogen pump CO2 hydrogenation reactor by film method

Abstract

The invention belongs to the technical field of electrochemical engineering and relates to a method for controlling the cathode potential in an electrochemical hydrogen pump CO2 hydrogenation reactorby a film method. The method is characterized in that a positive charge-modified proton exchange film is utilized in place of a liquid buffer layer, when electric energy is applied to the electrochemical hydrogen pump CO2 hydrogenation reactor, hydrogen protons generated by anode hydrogen dissociation pass through the positive charge-modified proton exchange film, and in-situ adsorbed hydrogen generated at a cathode undergoes hydrogenation reaction with CO2; positive charges are introduced into the proton exchange film through ion displacement or layer-by-layer self-assembling, the positive charges in the film migrate and accumulate toward the cathode under the action of an electric field to form a double electrode layer with the cathode, the cathode potential of CO2 hydrogenation is regulated, and CO2 hydrogenation reaction is promoted. The method is advantaged in that the modified film is utilized in place of the liquid buffer layer, the liquid phase environment can be avoided, interface problems are eliminated, the higher cathode potential can be achieved, moreover, the Donnan repulsion effect of the positive charges to the hydrogen protons is utilized, the hydrogen evolution reaction is stably inhibited for a long time, and relatively high CO2 hydrogenation efficiency is achieved.

Description

technical field [0001] The invention belongs to the technical field of electrochemical engineering, and relates to a membrane method for regulating the electrochemical hydrogen pump CO 2 Method for Cathodic Potential in Hydrogenation Reactor. Background technique [0002] Fossil fuels are the cornerstone of the world's energy structure, and their excessive combustion has caused serious energy crises and global warming. In 2015, the global CO 2 Annual emissions up to 30Gt, CO in the atmosphere 2 The concentration reached 401ppm. Capture and use of emitted CO 2 It can not only eliminate greenhouse gases, but also make rational use of carbon resources on the earth. Currently for CO 2 The utilization of CO is mainly divided into two categories, one is to directly convert CO 2 Used in various industries such as soft drinks, food, agricultural chemicals, welding, foaming, fire extinguishers; the second is to convert CO 2 Transformed into other chemical products and energy,...

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Problems solved by technology

The literature J.Mater.Chem.A,2015,3(6):3029 shows that the electrochemical hydrogen pump CO 2 The current efficiency of hydrogenation to produce formic acid and other products is lower than 5%, and the side reaction of hydrogen evolution is serious

However, introducing a liquid buffer layer in an electrochemical hydrogen pump, although higher CO 2 Hydrogenation efficiency, but there are also problems that are difficult to solve. For example, the pH value of the buffer solution decreases with the increase of reaction time, which leads to the gradual serious side reaction of hydrogen evolution; the liquid buffer layer will flood the gas transfer channel, increasing the hydrogen protons and CO 2 Mass transfer resistance; can also cause leakage, membrane fouling, etc.

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