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

Developing efficient catalysts for low reaction-temperature catalytic reduction of NO by CO (CO–DeNO x ) is desirable but very challenging. Here, we report that hierarchically interconnected porous (HIP) Mn x Co 3- x O 4 spinels, synthesized by a facile citric acid-assisted sol–gel method, can act as highly efficient catalysts for CO–DeNO x . The obtained Mn 0.3 Co 2.7 O 4 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 Mn 3+ , Mn 4+ , and Co 3+ species in the Co–O–Mn structure enables the high catalytic activity and the effective redox-cycling of the Co 3+ and Co 2+ adsorption sites; (ii) the HIP structure can significantly enhance gas diffusion. This work offers an avenue to design metal oxide catalysts for CO–DeNO x by effectively controlling the doping metal concentration and oxidation states of the active components.