Ammonia synthesis method for electrocatalytic reduction of nitrogen, and catalyst used in method

Abstract

The invention discloses a transition metal monatomic catalyst for electro-catalytic synthesis of ammonia. The catalyst is prepared by adopting a photodeposition method according to the following steps: preparing a carbon material serving as a carrier by utilizing carbon powder, sodium nitrate, concentrated sulfuric acid, potassium permanganate, deionized water and the like; dispersing TiO2 and thecarbon material in a mixed solvent composed of water and an organic solvent, adding a transition metal salt, uniformly mixing, reacting at room temperature under illumination, freezing and curing theobtained reaction product, and carrying out vacuum freeze drying to obtain the transition metal monatomic catalyst. The invention also provides an ammonia synthesis method for electrocatalytic reduction of nitrogen by using the transition metal monatomic catalyst. The method for synthesizing ammonia has the characteristics of simple and economic process, environmental friendliness, high yield andthe like.

Description

technical field [0001] The invention relates to an electrochemical synthesis method of ammonia. Background technique [0002] Ammonia is an important inorganic chemical product and the main raw material for the fertilizer industry and basic organic chemical industry. In addition, ammonia is also a carbon-free energy carrier, and its combustion products are nitrogen and water. Large-scale production of ammonia can replace most of the current liquid fuel consumption. It is considered to be one of the most promising green and sustainable fuel materials in the future. The world is actively developing the application of ammonia in heavy transportation, power generation, distributed energy storage and other fields. The consumption of ammonia is huge, and with the development of industry and agriculture, the demand for ammonia will continue to increase. At present, the source of ammonia in the world is mostly synthetic ammonia, except for a small amount of by-products recovered f...

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Problems solved by technology

Haiyuan Zou reported an ultrathin chlorine-doped graphene catalyst for the electrocatalytic reduction of nitrogen with an ammonia production rate of 10.7 μg h at a potential of -0.45 V (vs RHE) -1 cm -2 mg -1 Cat. , the Faradaic efficiency is 8.7% (ACSCatalysis, 2019, 9(12): 10649-10655.), it can be seen that the electrocatalytic nitrogen reduction is affected by the relatively stable nitrogen gas and the existence of hydrogen evolution competition reactions, and there are low ammonia production rates and low Faradaic efficiency. question

Hongjie Yu reported a thin film material mAu 3 Pd / NF was used for electrocatalytic nitrogen reduction with an ammonia production rate of 24.02 μg h -1 cm -2 mg -1 Cat. , the Faraday efficiency is 18.16% (ACS Applied Materials & Interfaces, 2020, 12(1): 436-442), although the performance of the catalyst is slightly improved compared with the previous work, but the catalyst materials used are expensive and costly

Wenjie Zang reported a nitrogen-doped carbon-supported copper single-atom catalyst for electrocatalytic nitrogen reduction. In HCl electrolyte, the obtained ammonia production rate was 49.3 μg h -1 cm -2 mg -1 Cat. , the Faraday efficiency is 11.7% (ACSCatalysis, 2019, 9(11): 10166-10173.), but this method has the problem of introducing nitrogen impurities to cause inaccurate test results, and the source of nitrogen in the product should be verified

[0007] To sum up, the early H-B ammonia synthesis had problems such as harsh conditions and high energy consumption. The recent electrochemical synthesis of ammonia has problems such as low yield, low Faraday efficiency, expensive catalyst materials, and inconsistent testing standards. To achieve efficient and green ammonia production, not only Involved in electrochemical system design, but also in efficient and economical catalyst development

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