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

Abstract Herein, we synthesize the hydroxyl-enriched e-MnO 2 catalyst (MnO 2 -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-MnO 2 . MnO 2 -AT exhibits the high activity and selectivity for preferential oxidation of CO in the H 2 -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 MnO 2 -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 CO 2 desorption from bicarbonates than carbonates promotes the CO oxidation process.