Achieving Sulfur Tolerance in CO₂ Methanation over Ni-Based Catalysts: Protective Effects of Fe

Abstract

Direct methanation of carbon dioxide (CO 2 ) in coal-fired flue gas presents a promising approach for achieving carbon neutrality without the energy-intensive CO 2 capture process. However, traditional Ni-based catalysts are easily deactivated by sulfur poisoning. In this study, a sulfur-tolerant Ni/γ-Al 2 O 3 catalyst with Fe modification ( x Fe–Ni/A) was developed, and the promoting mechanisms were elucidated. Experimental results showed that the 1Fe–Ni/A catalyst exhibited optimal Fe loading and maintained good activity in the presence of SO 2 . It was revealed that Fe addition facilitated the formation of the Ni–Fe alloy and modulated the catalyst’s surface chemistry, thereby promoting the reaction activity. Furthermore, the physicochemical and SO 2 adsorption properties of the catalyst suggested that Fe not only functioned as a protective agent for Ni sites against SO 2 but also inhibited overall SO 2 adsorption, resulting in enhanced sulfur resistance. This study provides valuable guidance for the design of sulfur-tolerant catalysts by doping sacrificial sites and modulating SO 2 adsorption using non-noble metals, laying the foundation for the scale-up industrial applications of CO 2 utilization in the SO 2 -containing environment.