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CN-121992431-A - CO at high current density2Preparation method and application of catalyst for preparing formic acid

CN121992431ACN 121992431 ACN121992431 ACN 121992431ACN-121992431-A

Abstract

A preparation method and application of a catalyst for preparing formic acid from CO 2 under high current density belong to the field of CO 2 electroreduction. The catalyst takes InO (OH) as a substrate, ionic liquid is introduced to modify the InO (OH), and the ionic liquid is prepared by reacting corresponding quaternary phosphonium chloride and trifluoromethanesulfonamide. Wherein quaternary phosphonium cations can form a local electric field at a cathode in CO 2 electroreduction, so that a reaction intermediate of formic acid is generated stably, and the selectivity of a product is greatly improved. The anions have strong hydrophobicity, obviously inhibit hydrogen evolution side reaction, have the function of enriching CO 2 and can form a high-concentration CO 2 local microenvironment. Under the synergistic effect of anions and cations, the problems of weak adsorption capacity, low catalytic activity and the like of the indium-based catalyst on CO 2 are effectively solved, and the catalyst still has good formic acid Faraday efficiency under ampere-level current density. The preparation method of the invention is simple and easy to popularize.

Inventors

  • Hao Leiduan
  • WANG RUOYIN
  • SUN ZHENYU

Assignees

  • 北京化工大学

Dates

Publication Date
20260508
Application Date
20260123

Claims (9)

  1. 1. The catalyst for preparing formic acid by CO 2 under high current density is characterized by modifying InO (OH) by ionic liquid, wherein the ionic liquid is selected from one or more of tributyl methyl phosphonium bis (trifluoromethanesulfonyl) imine ([ P 4441 ][NTf 2 ]), tetrabutyl phosphonium bis (trifluoromethanesulfonyl) imine ([ P 4444 ][NTf 2 ]), tributyl (2-methoxyethyl) phosphonium bis (trifluoromethanesulfonyl) imine ([ P 444(2OMe) ][NTf 2 ]).
  2. 2. The method for preparing the catalyst for preparing formic acid by CO 2 under the high current density as set forth in claim 1, which is characterized by comprising the following steps: (1) The preparation of the ionic liquid comprises the steps of mixing and reacting corresponding quaternary phosphonium chloride and corresponding trifluoromethanesulfonamide according to a certain proportion, separating out an organic phase, washing with water, and then drying in vacuum to obtain the required ionic liquid, or directly obtaining the ionic liquid commercially; (2) Weighing indium nitrate, dissolving in absolute ethyl alcohol, stirring uniformly to form a solution A, slowly adding glycol into the solution A, continuously stirring until the solution becomes transparent to form a solution B, transferring the solution B into a stainless steel autoclave for solvothermal reaction, and treating after the reaction to obtain a catalyst InO (OH); (3) Mixing the ionic liquid with the catalyst InO (OH) in the step (2) according to a certain mass fraction, adding a small amount of isopropanol to obtain a mixture, uniformly stirring, and then drying to remove the isopropanol solvent to obtain the ionic liquid modified catalyst.
  3. 3. The method according to claim 2, wherein the quaternary phosphonium chloride in step (1) comprises one or more of tributyl methyl phosphonium chloride, tetrabutyl phosphonium chloride and tributyl (2-methoxyethyl) phosphonium chloride, the mixing molar ratio of the quaternary phosphonium chloride salt to the trifluoromethanesulfonamide is 1:2, the mixture is stirred at 60 ℃ for 10 h, the product is collected, and then the product is dried in vacuum at 80 ℃ to obtain the required quaternary phosphonium salt ionic liquid.
  4. 4. The process according to claim 2, wherein the volume ratio of absolute ethanol to ethylene glycol used in step (2) is 2:1.
  5. 5. The method according to claim 2, wherein the condition of uniform solution a is continuous stirring for 30-60 min, and the condition of transparent solution B is continuous stirring for 30-60 min; The solvothermal reaction is carried out under the condition of heating at 160 ℃ for 5 h; the reaction is processed by alternately washing with absolute ethyl alcohol and deionized water after centrifugation, and then drying in a vacuum drying oven.
  6. 6. The process according to claim 2, characterized in that the ionic liquid added in step (3) is 20-40 wt%, preferably 30% by weight of the mass of the ionic liquid modified catalyst; The small amount of isopropanol added into the mixture is only required to stir and mix the ionic liquid and the InO (OH) uniformly, and the condition of uniform stirring is continuous stirring for 20-24 hours.
  7. 7. Use of a catalyst prepared according to the method of any one of claims 2-6 for electrocatalytic reduction of CO 2 to formic acid.
  8. 8. The use according to claim 7, wherein the CO 2 electrocatalytic reduction system is carried out in a flowing cell, wherein the cathode of the cell adopts a commercial gas diffusion layer and then carries the ionic liquid modified catalyst, a silver-silver chloride electrode is used as a reference electrode, a platinum sheet is used as an anode, the electrolyte is alkaline electrolyte, the electrocatalytic CO 2 process continuously introduces CO 2 gas into the cathode for electrocatalytic reduction, and the catalyst has good catalytic activity at ampere level current density of-0.8 a ∙ cm -2 ~-1.4A∙cm -2 .
  9. 9. The method according to claim 8, wherein the electrolyte is 1M KOH.

Description

Preparation method and application of catalyst for preparing formic acid from CO 2 under high current density Technical Field The invention relates to the field of electrocatalytic CO 2 reduction, in particular to a preparation and modification method and application of a catalytic material for modifying an indium-based catalyst by using ionic liquid and reducing CO 2 into formic acid by high-performance electrocatalytic. Background Since the industrial revolution, the dependence of human society on fossil energy causes the concentration of room gases such as CO 2 in the atmosphere to rise sharply, and a series of serious global environmental crisis such as global climate warming, extreme weather frequency, sea level rising and the like are caused. Under the background, the electrocatalytic CO 2 reduction is taken as a low-carbon technology capable of realizing large-scale carbon emission reduction while continuing the use of fossil energy, and has profound scientific significance and wide application prospect. Among the numerous products of CO 2 electroreduction, formic acid is not only important liquid fuel and chemical raw materials, but also a safe liquid hydrogen carrier, and has higher economic value and convenient storage and transportation. As one of the key research directions in the current electrocatalytic CO 2 reduction field, the indium-based material has excellent intrinsic selectivity on the formic acid generation path due to the unique electronic structure and surface properties, and has become a core catalyst system of great interest in the field. The ionic liquid is a green solvent, has the multiple advantages of high conductivity, wide electrochemical window, high solubility of CO 2, adjustable anions and cations, and the like, has been developed as an electrolyte for CO 2 reduction reaction to improve the catalytic performance, but the problems of high viscosity, high cost, mass transfer limitation and the like still remain key short plates for limiting the practical application of the ionic liquid. The ionic liquid is combined with the catalyst in the form of a modification layer, a composite carrier and the like, so that the activity and the selectivity of the ionic liquid in the electrocatalytic CO 2 reduction process are expected to be further improved, and the ionic liquid is one of potential research strategies at present. Disclosure of Invention The invention provides a preparation method for modifying InO (OH) by using ionic liquid with a specific function, which is used for electrocatalytic CO 2 reduction to produce formic acid, and the catalytic activity is obviously improved while the defect that the ionic liquid is used as an electrolyte is avoided. Most of the traditional catalysts have the problems of difficult activation, serious hydrogen evolution competition reaction, selectivity under high current density and the like, and particularly, the indium-based catalysts show inherent weak CO 2 adsorption affinity and are difficult to realize industrial application. The invention aims to solve the defects of the prior art, and synthesizes a typical indium-based material InO (OH), and by introducing an ionic liquid with a specific function, preferably one or more of tributyl methyl phosphonium bis (trifluoromethanesulfonyl) imine ([ P 4441][NTf2 ]), tetrabutyl phosphonium bis (trifluoromethanesulfonyl) imine ([ P 4444][NTf2 ]), tributyl (2-methoxyethyl) phosphonium bis (trifluoromethanesulfonyl) imine ([ P 444(2OMe)][NTf2 ]), the surface of the catalyst is modified, and the formic acid selectivity and the formic acid Faraday efficiency of the modified catalyst under high current density are improved obviously. The preparation method of the catalyst for preparing formic acid by electrocatalytic CO 2 reduction under high current density comprises the following steps: (1) The preparation of the ionic liquid comprises the steps of mixing and reacting corresponding quaternary phosphonium chloride and corresponding trifluoromethanesulfonamide according to a certain proportion, separating out an organic phase, washing with water, and then drying in vacuum to obtain the required ionic liquid, or directly obtaining the ionic liquid commercially; (2) Weighing indium nitrate, dissolving in absolute ethyl alcohol, stirring uniformly to form a solution A, slowly adding glycol into the solution A, continuously stirring until the solution becomes transparent to form a solution B, transferring the solution B into a stainless steel autoclave for solvothermal reaction, and treating after the reaction to obtain a catalyst InO (OH); (3) Mixing the ionic liquid with the catalyst InO (OH) in the step (2) according to a certain mass fraction, adding a small amount of isopropanol to obtain a mixture, uniformly stirring, and then drying to remove the isopropanol solvent to obtain the ionic liquid modified catalyst. Further, in the step (1), the quaternary phosphonium chloride comprises one or more of tr