阅读说明：本技术 一种基于碳酸盐协同作用的二价铜二氧化碳还原催化剂及其制备方法 (Bivalent copper carbon dioxide reduction catalyst based on carbonate synergistic effect and preparation method thereof ) 是由 周嵬 孙增森 吴心浩 谢峰华 郭亚楠 邵宗平 于 2020-04-13 设计创作，主要内容包括：本发明公开了一种基于碳酸盐协同作用的二价铜二氧化碳还原催化剂及其制备方法,首先通过复分解反应在铜酸镧钙钛矿型氧化物上原位生长碳酸镧,然后将其与活性炭混合制备成电极浆料滴涂在玻碳工作电极上。在电催化二氧化碳还原反应过程中碳酸镧起到传递碳酸根参与反应的作用,能够显著提高碳酸根参与反应的效率,能够稳定存在的二价铜作为高效转化二氧化碳制一氧化碳的活性位点。发明制备的材料能够在常温常压下以接近60%的法拉第效率一步法制备乙烯,并且材料合成方法简单,原料成本低,具有一定工业价值,有望缓解当今能源和环境问题。(The invention discloses a divalent copper carbon dioxide reduction catalyst based on carbonate synergistic effect and a preparation method thereof. Lanthanum carbonate plays a role in transferring carbonate to participate in the reaction in the electrocatalytic carbon dioxide reduction reaction process, the efficiency of the carbonate participating in the reaction can be obviously improved, and the existing divalent copper can be stably used as an active site for efficiently converting carbon dioxide to prepare carbon monoxide. The material prepared by the invention can prepare ethylene at normal temperature and normal pressure by a one-step method with Faraday efficiency close to 60 percent, has simple material synthesis method, low raw material cost and certain industrial value, and is expected to relieve the current energy and environmental problems.)

1. the cupric carbon dioxide reduction catalyst is characterized by being La₂CuO₄The perovskite oxide is a main body, and lanthanum carbonate is loaded on the surface of the perovskite oxide.

2. The cupric carbon dioxide reduction catalyst of claim 1, wherein in one embodiment, lanthanum carbonate is dendritic.

3. The method of preparing a cupric carbon dioxide reduction catalyst according to claim 1, comprising the steps of:

step 1, preparation of La₂CuO₄A perovskite-type oxide;

step 2, dispersing perovskite type oxide in KHCO₃And introducing CO2 into the solution to react to generate lanthanum carbonate on the surface.

4. The method for preparing a cupric carbon dioxide reduction catalyst according to claim 3, wherein the perovskite type oxide in the step 1 is obtained by a sol-gel method, a solid phase reaction method, a coprecipitation method, a hydrothermal method or a combustion method.

5. The method of preparing a cupric carbon dioxide reduction catalyst as claimed in claim 3, wherein in one embodiment, the step of sol-gel process comprises: dissolving lanthanum nitrate and copper acetate in deionized water according to a stoichiometric ratio and uniformly stirring; adding Ethylene Diamine Tetraacetic Acid (EDTA) and citric acid monohydrate (CA) as metal ion complexing agents, and using ammonia water as a pH regulator of the mixed solution; heating and stirring the mixed solution to be gelatinous; then baking the mixture for 3 to 10 hours at the temperature of 180 ℃ and 250 ℃ to obtain precursor powder; calcining the precursor powder obtained in the step (a) at the temperature of 600-1000 ℃ in an oxygen atmosphere for 4-6 hours, preferably at the temperature of 900 ℃ for 5 hours; cooling and grinding to obtain La₂CuO₄A perovskite type oxide.

6. The method of preparing a cupric carbon dioxide reduction catalyst as claimed in claim 3, wherein in one embodiment, KHCO is in step 2₃Solution concentration 0.5-5M, CO₂The reaction time is 0.5-5 h.

7. Use of the cupric carbon dioxide reduction catalyst of claim 1 in the preparation of ethylene by reduction of carbon dioxide in a single step.

8. The use of claim 7, wherein in one embodiment, the use employs a three-electrode system, the reduction catalyst is the cathode, the silver-silver chloride is the reference electrode, and the Pt sheet is the counter electrode.

9. Use according to claim 7, in an implementationIn the mode, in the application, 0.1M KHCO is adopted in the electrolytic cell₃Dissolving the mixture, and introducing carbon dioxide gas for reaction.

Technical Field

The invention relates to the field of cathodes for electrochemically reducing carbon dioxide, in particular to a divalent copper catalyst based on a carbonate synergistic effect and an application of a preparation method thereof in preparing ethylene by electrically reducing carbon dioxide.

Background

Uncontrolled abuse of fossil fuels not only causes a serious energy crisis, but also causes a dramatic increase in the concentration of carbon dioxide in the atmosphere and in the ocean. The concentration of carbon dioxide in air increased from 280ppm in the early 19 th century to 385ppm now and research institutes predicted that 600ppm could be reached by 2100^[1]. The increase in carbon dioxide concentration leads to an increase in the annual average temperature, which in turn leads to an accelerated progression of desertification and frequent occurrence of extreme weather. The scheme is expected to reduce the concentration of carbon dioxide in the atmosphere by utilizing the carbon dioxide, convert clean energy with large space-time limitation (such as solar energy, wind energy, tidal energy and the like) into stable chemical energy, establish a sustainable carbon circulation system, and is a promising approach for solving the dual pressure of the current environment and resources^[2,3]. However, the carbon-carbon double bond in the carbon dioxide molecule makes the carbon dioxide molecule have high chemical stability, which limits the efficiency of electrochemical conversion. Therefore, one of the key problems to be solved in achieving this technology is the development of high performance electrocatalysts.

It is generally believed that only copper-based catalysts can reduce carbon dioxide to ethylene with high faradaic efficiency. This is due to the fact that, at the reaction kinetics level, copper has a moderate binding energy for most of the intermediates involved in the reaction^[4]. Nevertheless, the large overpotential, poor activity, and vigorous Hydrogen Evolution Reaction (HER) make bulk metallic copper almost impossible to use as a practical electroreduction carbon dioxide catalyst. Moreover, current research on copper-based catalysts for the electroreduction of carbon dioxide is often limited to the catalysts themselves. For example, in the study of copper oxide-derived copper catalysts, the influence of the crystal face, grain boundary, morphology and specific surface area of the catalyst on the catalytic performance was intensively studied^[5,6]. However, it is not limited toSo far, the synergy between the cocatalyst and the catalyst and the transfer process in the middle of the reaction have been studied little. The synergistic effect of the catalyst and the cocatalyst, even the interaction between the catalyst and the catalyst carrier, for practical use, has a great influence on the catalytic effect of the catalyst.

Reference documents:

[1]Gottschalk J,Skinner L C,Lippold J,et al.Biological and physicalcontrols in the Southern Ocean on past millennial-scale atmospheric CO₂changes.[J].Nature Communications,2016,7(11539):11539.

[2]Mikkelsen M.The teraton challenge：A review of fixation andtransformation of carbon dioxide [J].Energy&Environmental Science,2010,3(1):43-81.

[3]Zhang L,Zhao Z J,Gong J.Nanostructured Materials for HeterogeneousElectrocatalytic CO₂Reduction and their Related Reaction Mechanisms[J].Angewandte Chemie International Edition,2017,56(38).

[4]Bagger,A.,Ju,W.,Varela,A.S.,Strasser,P.&Rossmeisl,J.Electrochemical CO₂Reduction:A Classification Problem[J].Chemphyschem2017,18.

[5]Choi,C.et al.A Highly Active Star Decahedron Cu Nanocatalyst forHydrocarbon Production at Low Overpotentials[J].Advanced Materials,2018,31(18):54-55.

[6]Li C W,Kanan M W.CO2 reduction at low overpotential on Cuelectrodes resulting from the reduction of thick Cu₂O films[J].Journal of theAmerican Chemical Society,2012,134(17):7231.

disclosure of Invention

The invention aims to provide a divalent copper carbon dioxide reduction catalyst based on the synergistic effect of carbonate, a preparation method thereof and application of the catalyst in preparing ethylene by one-step method of electrically reducing carbon dioxide.

In a first aspect of the present invention, there is provided:

a bivalent copper carbon dioxide reduction catalyst, which is prepared byLa₂CuO₄The perovskite oxide is a main body, and lanthanum carbonate is loaded on the surface of the perovskite oxide.

In one embodiment, the lanthanum carbonate is dendritic.

In a second aspect of the present invention, there is provided:

the preparation method of the bivalent copper carbon dioxide reduction catalyst comprises the following steps:

step 1, preparation of La₂CuO₄A perovskite-type oxide;

step 2, dispersing perovskite type oxide in KHCO₃In solution, and introducing CO₂The reaction proceeds to form lanthanum carbonate on the surface.

In one embodiment, the perovskite-type oxide in step 1 can be obtained by a sol-gel method, a solid-phase reaction method, a coprecipitation method, a hydrothermal method, a combustion method, or the like.

In one embodiment, the sol-gel process comprises the steps of: dissolving lanthanum nitrate and copper acetate in deionized water according to a stoichiometric ratio and uniformly stirring; adding Ethylene Diamine Tetraacetic Acid (EDTA) and citric acid monohydrate (CA) as metal ion complexing agents, and using ammonia water as a pH regulator of the mixed solution; heating and stirring the mixed solution to be gelatinous; then baking the mixture for 3 to 10 hours at the temperature of 180 ℃ and 250 ℃ to obtain precursor powder; calcining the precursor powder obtained in the step (a) at the temperature of 600-1000 ℃ in an oxygen atmosphere for 4-6 hours, preferably at the temperature of 900 ℃ for 5 hours; cooling and grinding to obtain La₂CuO₄A perovskite type oxide.

In one embodiment, the KHCO in step 2₃Solution concentration 0.5-5M, CO₂The reaction time is 0.5-5 h.

In a third aspect of the present invention, there is provided:

the application of the bivalent copper carbon dioxide reduction catalyst in preparing ethylene by reducing carbon dioxide in one step.

In one embodiment, the application uses a three-electrode system, the reduction catalyst is the cathode, the silver-silver chloride is the reference electrode, and the Pt sheet is the counter electrode.

In one embodiment, the application is to use 0.1M KHCO in an electrolytic cell₃Dissolving the mixture, and introducing carbon dioxide gas for reaction.

In one embodiment, the use is in a cupric carbon dioxide reduction catalyst for the production of C₂H₄Faraday efficiency or reduction of H yield₂The faraday efficiency.

Advantageous effects

The divalent copper catalyst based on the synergistic effect of the carbonate has excellent performance on the electro-reduction of carbon dioxide into ethylene, and the performance is superior to that of the traditional copper foil and copper oxide catalyst. The method has great help for understanding the mechanism of the carbon dioxide electrocatalytic reaction and reducing the concentration of carbon dioxide in the atmosphere. La to which the present invention relates₂CuO₄The perovskite type oxide can be produced by the traditional sol-gel method, the solid phase reaction method and other processes. The carbonate promoter can be obtained by liquid phase reaction in a solution of potassium bicarbonate with a molar concentration of 0.1M in La₂CuO₄The dendritic lanthanum carbonate grows on the surface of the perovskite type oxide in situ, the preparation method is simple, and the method is suitable for large-scale preparation.

Drawings

FIG. 1 shows La according to the present invention₂CuO₄Crystal structure schematic of perovskite catalyst.

FIG. 2 shows La according to the present invention₂CuO₄Perovskite type oxide (XRD refinement) profile.

FIG. 3 shows La according to the present invention₂CuO₄(XRD) patterns of different reaction times of perovskite oxides with carbon dioxide.

FIG. 4 is La₂CuO₄Perovskite type oxide is 0.1M KHCO₃Reacting the solution with carbon dioxide gas for 3 hours and 5 hours to obtain the growth condition of lanthanum carbonate crystal branches.

FIG. 5 shows La according to the present invention₂CuO₄TEM of perovskite type oxides.

FIG. 6 isLa with crystal branched lanthanum carbonate on surface₂CuO₄The catalyst radiates Cu-L edge spectrogram synchronously.

FIG. 7 shows La with dendritic lanthanum carbonate on the surface according to the present invention₂CuO₄A synchronous radiation Cu-K edge spectrum in the reaction process of the catalyst.

FIG. 8 shows La with dendritic lanthanum carbonate on the surface according to the present invention₂CuO₄The catalyst is 0.1M KHCO₃Graph of faradaic efficiency versus voltage for products in solution

FIG. 9 shows La with dendritic lanthanum carbonate on the surface according to the present invention₂CuO₄The catalyst is 0.1M KHCO₃Stability test results in solution.

FIG. 10 shows La according to the present invention₂CuO₄TEM after reaction of perovskite oxide with carbon dioxide.

FIG. 11 is La₂CuO₄La with different growth conditions of perovskite type oxide and lanthanum carbonate crystal branches₂CuO₄Faradaic efficiency comparison of catalytic carbon dioxide to ethylene.

Detailed Description

To enhance the structural formula A₂BO₄The RP type perovskite oxide has the catalytic effect on the electro-reduction of carbon dioxide, and the material adopted in the invention is La₂CuO₄The perovskite type oxide is used as a base material, can keep stable divalent copper, and the divalent copper is used as a reaction active site for electrically reducing carbon dioxide, and the crystal form of the oxide is perfect and exists in a black powder shape. In addition, the method is optimized in a mode of growing the crystal branch-shaped carbonate on the surface of the perovskite type oxide in situ. The crystal branch-shaped lanthanum carbonate is used as a cocatalyst to transfer carbonate to participate in the reaction, so that the Faraday efficiency of converting carbon dioxide into ethylene by electroreduction is improved.