Ammonia synthesis by pressure swing in plasma reactor

2022 Fiscal Year Final Research Report

• Project/Area Number: 20H01891
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 14030:Applied plasma science-related
• Research Institution: Tokyo Institute of Technology
• Principal Investigator: Mori Shinsuke 東京工業大学, 物質理工学院, 准教授 (80345389)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: Ammonia synthesis / Plasma chemistry / Pressure swing / Non-thermal plasma

Outline of Final Research Achievements

A pressure swing plasma reactor was fabricated and ammonia synthesis experiments were conducted. As a result, an energy efficiency of 0.39 g-NH3/kWh was obtained under pressure swing conditions of 0.8 to 2.3 bar, while the maximum energy efficiency was 0.23 g-NH3/kWh in the experiment where the pressure was kept at a constant value. In the pressure swing system, the amount of ammonia produced saturated with increasing plasma input power, and conversely, the amount of ammonia produced did not decrease significantly with decreasing plasma input power. As a result, the highest energy efficiency of 2.0 g-NH3/kWh was obtained at the lowest plasma input power conditions tested in the 0.4 to 1.2 bar pressure swing system. We conclude that the reason for the improvement in ammonia synthesis efficiency in the pressure swing method is attributed to the promotion of products or intermediate desorption from active sites during depressurization during low pressure period in pressure swing cycles.

Free Research Field

Plasma chemistry

Academic Significance and Societal Importance of the Research Achievements

本研究において、圧力スイングをさせながらプラズマ中でアンモニア合成をすることで、アンモニアの合成速度およびアンモニア合成のエネルギー効率が大幅に向上することが示された。また、その反応メカニズムについて、推論を行った。これらの結果は、プラズマを利用しない反応システムに対しても応用される研究成果であり、触媒を用いた反応システムに対しても応用できる可能性が示唆されており、また、アンモニア以外の反応システムに対して適応することも可能であることから、本研究成果の学術的意義および社会的意義は大きいと言える。