https://doi.org/10.1016/j.gce.2021.11.009
“With the fast development of DFMs, iCCC technology has attracted significant attention since it paves an innovative route by converting the captured CO2 from flue gas into value-added chemicals. Reaction conditions especially the temperature matching between two processes of CO2 capture and conversion are critical for a successful iCCC, as both thermodynamics and kinetics of adsorption and catalytic reaction depend on the temperature. Based on the thermodynamic analysis of reaction changes with the temperature, the iCCC-Methane approach at intermediate temperature and the iCCC-Syngas approach at high temperature are discussed in detail, respectively. In terms iCCC-Methane, no additional heat needs to be input due to the exothermic processes of both adsorption and conversion stages, however, the adsorption capacity is not high enough for efficient methane production in the subsequent conversion process. Whereas in terms of iCCC-Syngas, the exothermic calcium looping and the endothermic DRM or RWGS process can make the energy utilization more efficient but also remain more challenges in matching. The major difficulties are the stability of DFM caused by CaO sintering and catalyst deactivation by the carbon deposit at such a high temperature. Moreover, iCCC-Ethylene is a novel route for CO2 utilization and manufacturing of value-added ethylene.”
“In view of up-scaling the iCCC technology to the industrial scale, the dual-fixed-bed reactors mode by switching the flue gases and reactant gases is a practicable approach. However, challenges like the even distribution of gases, the safety of frequent valve-switching; the accurate temperature and heat managements, and the possibility of compressing at high temperature need to be addressed for further development. To overcome the limitation of the fixed-bed, the dual-fluidized-bed reactors mode by the circulation of DFM particles is proposed. The feasibilities like the full utilization of energy, the even temperature distribution, and thorough contact of reactants make the iCCC processes easier to be operated. Meanwhile, it puts forward higher requirements for the mechanical strength of DFMs. Therefore, it is urgent to develop DFMs with excellent adsorption and catalytic performance, as well as highly stable activity and mechanical durability. Current researches mainly focus on the development of novel DFMs in laboratory scale, but lack of enough data under harsh conditions such as exposing DFMs to O2, SOx, NOx, and H2O atmospheres, and long-life testing. Moreover, further amplification and molding studies are very important for real applications.”