Chemical looping CO2 capture and in-situ conversion: Fundamentals, process configurations, bifunctional materials, and reaction mechanisms

As an emerging and promising technology to debate the energy and environment issues raised by anthropogenic CO2 emissions, chemical looping CO2 capture and in-situ conversion (CL-ICCC) exhibits the merit of high efficiency, low cost, and high safety to achieve integrated CO2 capture and conversion (ICCC) by eliminating the purification, compression, transportation, and storage procedures. However, the interpretation and state-of-the-art of CL-ICCC are still unclear, which contribute to a harmful effect on promoting this technology for industrial applications. Herein, this work presents a timely review on CL-ICCC by giving fundamental discussions on definition, process configuration, bifunctional material, reaction mechanism and thermo-economic behavior. Based on the product distributions (syngas, CO, CH4, C2H4/C3H6), CL-ICCC systems using abundant bifunctional materials with flexible combinations of sorbents and catalysts are classified to satisfy the demand of customers. Lots of moderating strategies are proposed to enhance the activity and stability of bifunctional material, meanwhile, reaction mechanism is revealed to explain the underlying reason for superior performance. The challenges and future prospectives from the aspects of microscopic reaction mechanism, bifunctional material rational design, reaction equipment development and system integration and optimization are discussed to provide possible suggestions. This review aims to illustrate CL-ICCC more clearly and accelerate its commercial demonstration.