N2O and NO formation from NH3 oxidation over MnOx/TiO2 catalysts.

Abstract The reactions of NH 3 and catalyst oxygen in MnO x /TiO 2 catalysts were studied under gaseous O 2 -deficient condition, in order to research N 2 O and NO formation from NH 3 oxidation by catalyst oxygen and also to clarify the authentic role that MnO x /TiO 2 catalysts played in the process. Furthermore, multiple characterization methods were applied to contrastively analyze the physical-chemical properties and the microstructures of the fresh catalyst and the served catalyst, so as to help investigate the possible intrinsic mechanism of N 2 O and NO generation. Experimental results validated that N 2 O and NO originated from NH 3 oxidation by catalyst oxygen obviously, while the characterization results indicated that both the surface absorbed oxygen and the lattice oxygen participated in the process and resulted in the formation of N 2 O and NO. The consumption of catalyst oxygen led to the arising of new small pores inside the catalyst, bringing about the decrease of the average pore diameter and the increase of the total pore volume and the surface area of the catalyst. The NH 3 oxidation process also made partial adjacent catalyst particles gather together, accounting for the aggregation and the non-uniform dispersion of catalyst particles. [ABSTRACT FROM AUTHOR]