Chemical looping approaches to decarbonization via CO2 repurposing

Abstract

Active areas of research on chemical looping technologies for the conversion of CO2 to CO are contrasted and discussed, including current performance, methods for material design, and next steps in expanding their development. Generation of CO from CO2 is of interest in sustainable chemistry and engineering to convert anthropogenic CO2 emissions into feedstock for Fischer–Tropsch (FT), methanol to gasoline (MTG), gas-to-liquid (GTL), and other synthesis pathways for fuels and materials. Chemical looping strategies have been identified which not only produce CO, but also H2 from H2O and methane sources, supplying the other key component of syngas. Configurations of these chemical looping technologies into the materials economy potentially constitute sustainable carbon loop cycles for fuels as well as carbon sequestration into industrial and commercial materials. Major areas of research in CO2 conversion by chemical looping, collectively referred to here as CO2CL, including Solar-Thermal Chemical Looping (STCL), Reverse Water Gas Shift Chemical Looping (RWGS-CL), Chemical Looping Reforming (CLR), Super Dry Reforming (SDR), Autothermal Catalyst Assisted Chemical Looping (ACACL), and Reverse Boudouard Reforming (RBR) are discussed in terms of their process characteristics, historical development of oxygen carrier (OC) material, state of the art methods for material design, and future work needed to advance the scale-up of these technologies. This perspective centers around the non-methane utilizing processes for CO2CL, focusing on the phenomena of oxygen transfer between gas molecules and the oxygen carrier (OC).