One-step direct ammonia synthesis by pulse-modulated microwave plasma at atmospheric pressure  

作　　者：Wei WANG Yao LI Zhaoquan CHEN Sisi LI Yi FENG Zhi ZHENG Dezheng YANG Yue LIU 王伟;李瑶;陈兆权;李思思;冯旖;郑直;杨徳正;刘悦

机构地区：[1]Key Laboratory of Materials Modification by Laser,Ion,and Electron Beams(Dalian University of Technology),Ministry of Education,Dalian 116024,People’s Republic of China [2]School of Physics,Dalian University of Technology,Dalian 116024,People’s Republic of China [3]Anhui Province Key Laboratory of Power Electronics and Electrical Control,Anhui University of Technology,Ma’anshan 243032,People’s Republic of China

出　　处：《Plasma Science and Technology》2025年第4期112-121,共10页等离子体科学和技术(英文版)

基　　金：supported by National Natural Science Foundation of China(Nos.52077026,51977023,52177126 and 12475253);the Fundamental Research Funds for the Central Universities(No.DUT23YG227);the Dalian Life&Health Guiding Project(No.2023ZXYG34)。

摘　　要：In this study,we explored a one-step direct synthesis of NH3 under mild experimental conditions utilizing pulse-modulated microwave plasma technology at atmospheric pressure.At a substantial gas flow rate,a microwave plasma jet was formed and the microwave-assisted ammonia synthesis can be realized.Impacts of various parameters including the gas flow rate,gas component,microwave absorbed power,pulse modulation frequency,and pulse duty cycle on ammonia synthesis were systematically investigated.To indicate the reaction path of ammonia synthesis,the distributions of both the gas temperature and active species were also studied using optical emission spectra technology.It is found that a considerable amount of ammonia was directly synthesized without involvement of any catalysts,the highest ammonia production rate and energy efficiency(EE),up to 2.93μmol·min^(-1) and 6.64×10^(-2)g·(k W·h)^(-1),respectively,were achieved under low microwave power of 84.42 W.The duty cycle has obvious influences on the synthesis efficiency,compared to a duty cycle of 80%,the ammonia synthesis rate,EE and nitrogen conversion decreased by about 22%at a duty cycle of 100%.This finding underscores the significance of incorporating pulse modulation in the microwave discharge process for ammonia synthesis.Furthermore,it was found that vibrational excitation of microwave plasma has a significant driving effect on ammonia synthesis.

关 键 词：microwave plasma ammonia synthesis pulse modulation plasma jet microwave resonant cavity(Some figures may appear in colour only in the online journal) 

分 类 号：TQ113.2[化学工程—无机化工]