Hierarchically interconnected porous MnxCo3-xO4 spinels for Low-temperature catalytic reduction of NO by CO

Abstract

Developing efficient catalysts for low reaction-temperature catalytic reduction of NO by CO (CO–DeNOx) is desirable but very challenging. Here, we report that hierarchically interconnected porous (HIP) MnxCo3-xO4 spinels, synthesized by a facile citric acid-assisted sol–gel method, can act as highly efficient catalysts for CO–DeNOx. The obtained Mn0.3Co2.7O4 displayed a much-enhanced catalytic performance with 87% NO removal at 100 °C and a wide active-temperature window (100–400 °C). Its superior activity stems from the following reasons: (i) the high-valence of Mn3+, Mn4+, and Co3+ species in the Co–O–Mn structure enables the high catalytic activity and the effective redox-cycling of the Co3+ and Co2+ adsorption sites; (ii) the HIP structure can significantly enhance gas diffusion. This work offers an avenue to design metal oxide catalysts for CO–DeNOx by effectively controlling the doping metal concentration and oxidation states of the active components.