Promotional effect of N-doped CeO2 supported CoOx catalysts with enhanced catalytic activity on NO oxidation

A series of neoteric CoOx/N-doped CeO2 catalysts were synthesized by partly substituting the lattice oxygen of CeO2 with nitrogen by a simple g-C3N4-modified sal-gel method and comprehensively characterized by XRD, H-2-TPR, XPS, BET, TEM, TG, UV-vis DRS, PL, EIS, NO(O-2)-TPD and EPR. The results demonstrated that: (1) The N-doped catalysts showed larger surface areas and pore volumes, which were favorable for the adsorption of reactant gas; (2) Replacing 0 with N could promote the reduction of resultant catalysts and assist cobalt oxide in changing the valence and the support in supplying the oxygen; (3) By a sal-gel method, the CoOx crystallites in these catalysts were encapsulated by CeO2 with only a small fraction of Co ions on the surface and strongly interacting with CeO2. Such structure maximized the interaction between CoOx and CeO2 in three dimensions, resulting in unique redox properties. Moreover, the prepared materials were evaluated in the selective catalytic oxidation of NO. The results showed that the N-doped materials exhibited higher catalytic activity than the un-doped one due to those physicochemical changes. An enhanced mechanism on the improvement of catalytic performance was proposed, and this could pave the way for the designed and synthesis of new highly catalytic activity catalysts. (C) 2015 Elsevier B.V. All rights reserved.