Abstract
Significant progress has been made in nitrogen carriers and chemical looping ammonia production (CLAP). However, a comprehensive write-up integrating a review of the previous work and perspectives on the strategies needed for overcoming the existing challenges has not been reported yet. This work with several unique characteristics is to fill the blank. For example, for the first time, CLAP methods are classified according to their reaction mechanisms. Also, the performances of nitrogen carriers and catalysts and characteristics of process thermodynamics and kinetics of each type of CLAP are systematically and integrally analyzed. Moreover, the significant challenges existing in CLAP are identified. The strategies for overcoming the challenges are proposed, including plasma-based CLAP improvement and artificial intelligence (AI) guided CLAP system performance enhancement.
[Display omitted]
Ammonia, primarily made with Haber-Bosch process developed in 1909 and winning two Nobel prizes, is a promising noncarbon fuel for preventing global warming of 1.5 °C above pre-industrial levels. However, the undesired characteristics of the process, including high carbon footprint, necessitate alternative ammonia synthesis methods, and among them is chemical looping ammonia production (CLAP) that uses nitrogen carrier materials and operates at atmospheric pressure with high product selectivity and energy efficiency. To date, neither a systematic review nor a perspective in nitrogen carriers and CLAP has been reported in the critical area. Thus, this work not only assesses the previous results of CLAP but also provides perspectives towards the future of CLAP. It classifies, characterizes, and holistically analyzes the fundamentally different CLAP pathways and discusses the ways of further improving the CLAP performance with the assistance of plasma technology and artificial intelligence (AI).