CO₂ capture from large, concentrated emission sources can efficiently reduce CO₂ emission. A new chemical looping technology has been developed for CO₂ capture from coal-fired power plants and in-situ conversion into CH₄, also known as the integrated CO₂ capture and methanation (ICCM) process. It is realized via cycling dual function materials (DFMs) between the CO₂ capture reactor and methanation reactor, in which the DFMs consists of Na₂CO₃ sorbent coupled with catalytic Ru component on Al₂O₃ support. However, several pollutions carried by flue gas would cause significant issues when combining the ICCM with coal-fired power plants. In this work, we investigated the effect of fly ashes on the performance of dual function materials (DFMs). It was found that the presence of fly ashes decreased the CH₄ selectivity in methanation steps, from 86.6% to 66.6% and 57.8%, and promoted CO production. There was also an accelerated decline in the DFMs stability. By characterization, the fly ashes were adhered to the DFMs surface, causing pollution and agglomeration of Ru particles during the cyclic methanation steps. Thus, it presented a decreased activity for carbonate activation and CO hydrogenation, leading to the release of adsorbed CO during the methanation steps. In addition, the roles of SiO₂ and Fe element components in fly ashes were also identified, which were responsible for the synthesized influence of fly ashes.

Integrated CO2 capture and methanation,In-situ hydrogenation,Dual function materials,Fly ashes,Selectivity,Reactivity