Enhanced CO-SCR denitration on supported Rh-Mn/CoAlOx catalysts through Rh-Mn interaction

[Display omitted] •The catalytic efficiency of Rh-Mn bimetallic catalysts was investigated for the CO-SCR reaction.•The synthesis method using citric acid and ethylene glycol promotes dispersion of Rh.•The synergistic interaction between Rh and Mn enhances the adsorption and dissociation of NO.•The catalytic mechanism was elucidated through kinetic experiments and in-situ DRIFTs. The selective catalytic reduction of NO by CO (CO-SCR) presents an economical and promising approach to mitigate emissions of NOx and CO from motor vehicles. A bimetallic Rh-Mn supported catalyst Rh-Mn/CoAlO was synthesized through the reduction of citric acid and ethylene glycol, and subsequently employed in the CO-SCR reaction. Tests assessing its catalytic performance revealed that the Rh-Mn/CoAlO catalyst displayed superior CO-SCR activity, maintaining high efficiency (≥90 % at 230 °C) and stability while simultaneously reducing the usage of noble metals. Various characterization techniques, including H2-TPR, NO-TPD, CO-pulse, and XPS, indicated that the Rh-Mn/CoAlO catalyst possessed enhanced dispersion of noble metals. This increased dispersion ensured optimal contact between Rh and Mn, as well as the support, fostering a synergistic interaction that facilitated electron transfer. Consequently, the catalyst’s adsorption and activation capabilities for NO were significantly improved. In situ DRIFTs studies further elucidated that the catalyst primarily followed the E-R mechanism, wherein NO is adsorbed onto the catalyst surface, and subsequently, the N and O atoms generated from pyrolysis react with CO in the gas phase. The findings of this study are anticipated to offer an effective strategy for designing catalysts with exceptional low-temperature activity and high dispersibility for the reduction of NO using CO.