Carbon capture and storage (CCS) is one major strategy for mankind to combat climate change, in addition to developing renewable energy and improving end-use energy efficiency. However, most of current attention to CCS has been focused on developing separate CO2 capture or conversion techniques, while driving forward the CCS strategy requires new concepts for in-situ CO2 utilization by integrating the two technical steps, which has rarely been thought of yet. Therefore, we have proposed and experimentally demonstrated a novel thermochemical process to in-situ utilize CO2 by combining the calcium-looping CO2 capture reaction (CaL) and the CH4 dry reforming reaction (MDR) in one integrated chemical process, which we named ‘calcium-looping reforming of methane’. The proposed process uses a reductant (CH4) and a material (CaO-Ni bifunctional sorbent-catalyst) which are earth-abundant to achieve the in-situ conversion of CO2 to syngas. The proposed calcium-looping methane reforming process is demonstrated to effectively combine CO2 capture with its conversion, and exhibit superior reaction kinetics and energetics as compared with those of conventional calcium looping and CH4 dry reforming processes. Importantly, the proposed process could provide mutual benefits between the CaL and MDR reactions. On one hand, the in-situ consumption of CO2 through the MDR reaction drives the CaCO3 dissociation reaction according to Le Chatelier’s principle, which allows such an energy-intensive reaction to be operated with superior kinetics at lower temperatures as compared to those of conventional CaL. Thus, the sintering-caused material deactivation, which is a common issue restricting the development of the CaL-based CO2 capture technology, can be effectively mitigated. On the other hand, due to introduction of the CaO-based CO2 carrying cycle, the energy consumption for CO2 utilization and the fuel requirement for syngas production of the proposed process are 22% and 9% lower, respectively, than those of conventional MDR. The in-situ thermochemical CO2 utilization process proposed is capable of using various CO2-containing gases as a feedstock to reform CH4, and offers a chance to directly utilize the CO2 emitted in enormous quantities from its large stationary sources in an energy-efficient manner.

Integrating methane dry reforming into calcium looping for the synergetic capture and conversion of carbon dioxide

2019 Spring National Meeting

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