Thermodynamic and kinetic considerations of nitrogen carriers for chemical looping ammonia synthesis

Abstract Ammonia (NH 3 ) is a promising clean energy carrier, provided that its production driven by renewable rather than fossil fuel-based Haber–Bosch (H–B) process. Chemical looping ammonia synthesis (denoted as CLAS) can intervene in the ubiquitous scaling relations catalytic separately feeding reactants to nitrogen carrier achieve atmospheric operation, which provides an alternative synthetic route H-B The key of CLAS develop efficient N materials with suitable thermodynamic and kinetic properties. Metal nitrides metal imides are two kinds for process, H 2 O commonly used hydrogen sources NH . Here, we first analyze properties reactions various water or produce , fixation on metals hydrides, regeneration from oxides, respectively. calculation results display reduction main group hydroxide, early transition rare earth oxides corresponding metallic state nitridation late nitrides, limiting steps nitride carriers. imides, such lithium imide barium imide, have relatively proper thermodynamics two-step chemical reactions, however, their performance limited hydrogenation reaction. Moreover, thermodynamically unfavorable CLAS, propose potential electrochemical processes run loop, molten salt electrolytic cell solid electrolyte cell. Finally, put forward some strategies, controllable carriers adding catalysts, improve kinetics reactions.