Integrated CO2 capture and methanation from the intermediate-temperature flue gas on dual functional hybrids of AMS/CaMgO||Ni Co

• Dual-functional materials of CO 2 adsorption and catalyst AMS/CaMgO||Ni x Co y are developed. • Integrated CO 2 capture and methanation is successfully achieved at intermediate-temperature. • Superior CO 2 capture capacity, conversion efficiency and CH 4 selectivity are achieved. • The geometric distance between the sorbent and catalyst can modulate the product selectivity. • Porosity, AMS modification, and Ca doping result in excellent CO 2 capacity of AMS/CaMgO. The integrated CO 2 capture and conversion (iCCC) technology has caused more and more interests for the Carbon Neutrality as it can make full use of the heat of high-temperature or intermediate-temperature flue gas to achieve efficient CO 2 chemical utilization, avoiding additional costs for CO 2 transportation and producing value-added chemicals. Herein, we developed the dual functional adsorbent||catalyst hybrids of alkali metal salts (AMS)/CaMgO||Ni x Co y for the integrated CO 2 capture and methanation (iCCC-methanation) at the intermediate temperature of 350 o C. By loading alkali metal salts into porous CaMgO composites, the AMS/CaMgO shows a stable CO 2 adsorption performance with an excellent saturated capacity of 12.8 mmol g -1 at 350 o C. Meanwhile, CO 2 and H 2 can be simultaneously activated on the catalytic active sites of Co and Ni on the bimetal Ni x Co y alloy catalysts for the efficient methanation. After the temperature matching between CO 2 capture and conversion, an excellent iCCC-methanation performance with the CO 2 conversion efficiency near 93.4% and CH 4 selectivity of 88% are achieved in one dual-bed column at 350 o C. More importantly, the products selectivity between CH 4 and CO can be modulated by altering the packing configurations of sorbent/catalyst in the fixed-bed column, such as the dual-bed mode, multilayer mode, and physical mixing mode. Based on the elementary consecutive dynamic law, we revealed that the distance between the adsorption site and catalytic site plays a critical role for the CO 2 hydrogenation. The superior performance of this iCCC-methanation demonstrates the importance of the synergistic promotions between the CO 2 capture and in-situ conversion, as well as its promising application in CO 2 emission control.