A Robust Cu Catalyst for Low-Temperature CO Oxidation in Flue Gas: Mitigating Deactivation via Co-Doping

Abstract

CuCeTiOx (CCT) catalyst is considered as a promising prospect attributable to their high activity for low-temperature CO oxidation. However, rapid deactivation when treating humid flue gas hindered their industrial exploitation. The hydroxide ion (OH−) dissociated from H2O, and carbonate intermediates derived from CO/CO2 deposited on the catalyst surface of CCT catalyst, inhibits the CO oxidation by surface oxygen on active sites. In this study, the detrimental effect caused by H2O and CO2 were evaluated, and the performance of CCT catalysts were investigated and compared using in situ DRIFTs study. Further, intentional doping on the CCT using transition metal (e.g., Co and Mn) was performed to mitigate the catalyst deactivation caused by H2O and CO2. The incorporation of cobalt in Co-CCT altered the reaction pathway and mitigated the deactivation via enhancing the consumption of surface adsorbed OH- by CO, reducing the occupancy of active sites. Also, preferential adsorption of CO further suppressed the competition of OH- and CO2 towards active sites on catalyst attributable to the abundant oxygen vacancies and low coordinated metal (i.e., Cu+, Ce3+) in Co-CCT, which significantly enhanced the resistance to H2O and CO2 in the flue gas. This work thoroughly analyzed the mechanism of H2O and CO2 impacting the catalyst activity during low-temperature CO oxidation, is able to provide innovative insights for the design of highly-active and long-shelf life catalysts. The incorporation of cobalt in CuCeTiOx catalyst facilitates the formation of oxygen vacancies, the adsorption of CO, and the consumption of OH-, speeding up the CO oxidation to CO2 and promoting the resistance to deactivation caused by H2O and CO2 in the flue gas.