Cooperative enhancement of Ni/Ce-Fe-Mn-Ca dual functional materials for integrated CO2 capture and conversion to CO under near-equimolar H2/CO2 conditions

Abstract

Integrated CO₂ capture and utilization (ICCU) coupled with the reverse water-gas shift reaction offers a promising route to convert captured CO₂ into value-added CO using Ca-based dual functional materials (DFMs), providing an economically viable strategy for reducing CO₂ emissions from energy and industry sources. However, existing Ca-based DMFs typically require a high H₂/CO₂ ratio to achieve efficient catalytic CO generation from adsorbed CO₂. To address this limitation, this study develops a series of Ni and Ce co-modified Fe-Mn-Ca DFMs that enable high CO₂ conversion and CO yield under near-equimolar H₂/CO₂ conditions in a fixed-bed reactor. Results indicate that CaO modified with a Fe/Mn molar ratio of 7:3 exhibits a CO₂ capture capacity of 11.42 mmol g⁻¹ and subsequent CO₂ conversion of 58.7 %. Further modification of this optimized Fe-Mn-Ca material with Ni and Ce cooperative enhancement performance, achieving 61 % CO₂ conversion and 100 % CO selectivity at a H₂/CO₂ ratio of 1:1, with only 18 % decay over 10 consecutive cycles. Mechanistic insights into the cyclic CO₂ adsorption and hydrogenation processes, as well as performance attenuation, were elucidated through material characterization. The effective formation of formate intermediates is responsible for the production of CO from the adsorbed CO₂ under near-equimolar H₂/CO₂ conditions. Finally, comparative performance analysis and enhancement mechanisms are discussed. These findings establish a material foundation for ICCU systems targeting CO production in a serial dual-fluidized bed reactor.