Optimizing bimetallic and multimetallic Cu-based catalysts by promoters for enhanced reverse Water-Gas Shift reaction: Insights and stability assessments

Abstract

This study investigates bimetallic and multimetallic catalysts tailored for the reverse water gas shift (RWGS) reaction. Promoting with potassium and iron, while maintaining a constant copper content of 15 wt% on γ-alumina, revealed that bimetallic catalysts containing 7.5 wt% iron and 5 wt% potassium exhibit superior catalytic activity and stability. Among the multimetallic catalysts, the optimal composition was found to be in the 15 wt% Cu-5 wt% Fe-2.5 wt% K/γ-Al₂O₃ catalyst for the RWGS reaction. The prepared catalysts underwent assessments using various techniques such as N₂ adsorption-desorption, XRD, H₂-TPR, CO₂-TPD, and FESEM. Stability assessments conducted over 72 hours showcased sustained long-term performance for the optimized catalysts, highlighting the influential role of the hierarchical structure. Mesopores extended the catalyst lifetime by reducing permeation limits, while macropores facilitated diffusion process, enhancing selectivity and stability. This hierarchical design also improved mass transfer, amplifying reaction rates. The synthesized catalysts exhibited exceptional specificity, demonstrating 100 % selectivity for the RWGS reaction. Particularly, under H₂/CO₂=1, these catalysts displayed remarkable carbon dioxide conversion rates, indicating potential for enhancing Cu-based catalysts in RWGS reactions by maximizing active sites.