Enhanced propane and carbon monoxide oxidation activity by structural interactions of CeO2 with MnOx/Nb2O5-x catalysts

A series of CeO2-MnOx/Nb2O5-x catalysts, with monoclinic Nb2O5-x (pre-calcined at 1025 degrees C) as the carrier, were synthesized and evaluated for catalytic oxidation of C(3)H(8 )and CO. Strong interactions between CeO2 and MnOx/Nb2O5-x. were observed, and the catalyst with an optimal Mn/Ce ratio of 5.45 (1.24 wt% of CeO2) achieved 90% propane conversion at 290 degrees C and 90% CO conversion at 174 degrees C. The light-off temperature for 20% propane conversion occurred at similar to 192 degrees C and 20% CO conversion occurred at similar to 87 degrees C. The catalyst also showed very high stability during the long-term testing, even in the presence of water. Physicochemical characterizations and insitu DRIFTS indicated that the addition of CeO2 greatly reduces the MnOx particle sizes, increases the dispersion of MnOx, and results in the formation of a Ce-Mn-O solid solution as well as a new Nb-Mn-Ce based phase. The interaction between Nb2O5-x and Ce-Mn mixed oxides with an optimized Mn/Ce ratio promotes the formation of oxygen vacancies and reduced species (Nb4+, Ce3+ and Mn3+), which leads to the upgrading of redox properties and enhances the ability for binding intermediates during reaction, contributing to the high oxidation activity of the catalysts.