Structure of Ga2O3-Al2O3 prepared by sol–gel method and its catalytic performance for NO reduction by propene in the presence of oxygen

Catalytic performance of Ga2O3-Al2O3 prepared by sol–gel method for the selective reduction of NO with propene in the presence of oxygen was investigated. The activity of Ga2O3-Al2O3 increased with an increase in Ga2O3 loading up to 50 wt.%, and then decreased after that. The same tendency was observed for the specific activity normalized by BET surface area. The possibility of a synergistic effect between Ga2O3 and Al2O3 was suggested. X-ray diffraction (XRD) and extended X-ray absorption fine structure (EXAFS) revealed that a composite oxide in the form of [GaxAl(1−x)]2O3 (x<1) is uniformly formed by substitution of Ga3+ for Al3+ in the Al2O3 lattice. A reaction pathway in which nitrate species (NO3−) formed on the catalyst surface is reduced to nitrogen by the reaction with propene was proposed on the basis of the experimental results of in situ Fourier transform infrared (FT-IR) spectroscopy.