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

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.