Hydroxyl promoted preferential and total oxidation of CO over ε-MnO2 catalyst

Abstract

Abstract Herein, we synthesize the hydroxyl-enriched e-MnO2 catalyst (MnO2-AT) by simple acid washing. Acid washing destroys the sphere structure into fragments with abundant structure defects and maintains the crystal and pore structure of e-MnO2. MnO2-AT exhibits the high activity and selectivity for preferential oxidation of CO in the H2-rich stream, as well as the high activity for CO total oxidation. It can completely converts CO in preferential and total oxidation of CO at 170 °C and 90 °C, respectively, with a good stability. The acid washing treatment highly increases the surface hydroxyl groups on MnO2-AT. Our results demonstrate that with the aid of surface hydroxyl groups CO can easily form bicarbonate intermediates, which are more thermally unstable than carbonate intermediates. The faster CO2 desorption from bicarbonates than carbonates promotes the CO oxidation process.