Integrated Strategy for CO2 Capture and Catalytic Conversion Based on Fly Ash-Derived Catalysts

This research proposes using coal-fired power plant fly ash as a catalyst carrier, integrating CO2 adsorption with catalytic conversion to enhance CO2 capture efficiency. Nickel-based and manganese-based alkaline-modified fly ash (FA-AM) solid catalysts were synthesized using ultrasonic impregnation. CO2 adsorption, catalytic conversion properties, and the impact of SO2 and H2O were evaluated. The adsorption and catalysis mechanisms were summarized through characterization and experimental phenomena, and the integrated strategy was evaluated. The results indicated that the transition metals Ni and Mn augmented the specific surface area and pore volume of the support material. At 303 K and 1 bar, 30%-Ni/FA-AM and 30%-Mn/FA-AM achieved 4.36 and 3.82 mmol/g CO2 adsorption capacities. After 15 adsorption–desorption cycles, the adsorption performance decreased by only 8 and 13%, respectively. The adsorption kinetics were fitted using two kinetic models, with the pseudo-first-order kinetic model offering a better description of CO2 adsorption, suggesting that the adsorption process was predominantly physical. At 723 K and 1 bar, 30%-Ni/FA-AM showed 95.64% CH4 selectivity, while 30%-Mn/FA-AM achieved 74.47% CO selectivity. After 7 catalytic cycles, the catalytic capabilities decreased by 12.38 and 14.88%, respectively. These results indicate that the catalysts exhibit good cyclical stability and regeneration performance.