Review of chemical looping ammonia synthesis materials

Efforts towards global decarbonization rely on changes in chemical production, one critical process for nutrition and potential future hydrogen energy vectors is nitrogen fixation to ammonia by the Haber-Bosch reaction. Ammonia is produced at scale in centralized locations, then transported by tanker or pipeline to its end user. Chemical looping ammonia synthesis, or CLAS, is an alternative, low-pressure, decentralized, and renewable -powered alternative for ammonia production. The reaction proceeds in time-independent steps, nitrogen -fixation-hydrogenation cycles. A critical review of the materials studied for this application is needed as this subject of research grows and more literature is produced for this concept under different titles. The aim of this work is to synthesize many previous directions in the research and to provide perspective on future CLAS ma-terials development.