Promotional effect of H2O on the activity of In2O3‐doped Ga2O3–Al2O3 for the selective reduction of nitrogen monoxide

Effect of metal oxide additives on the catalytic performance of Ga2O3–Al2O3 prepared by the sol–gel method for the selective reduction of NO with propene in the presence of oxygen was studied. Of several metal oxide additives, the addition of In2O3 enhanced drastically the activity of Ga2O3–Al2O3 for NO reduction by propene in the presence of H2O. In addition, the activity of In2O3‐doped Ga2O3–Al2O3 catalyst was extremely intensified by the presence of H2O below 350°C. The promotional effect of H2O was interpreted by the suppression of undesirable propene oxidation and the removal of carbonaceous materials deposited on the catalyst surface. We also found that close interaction of In2O3 and Ga2O3 is necessary for the enhancement of activity by H2O. A lot of hydrocarbons except methane and oxygenated compounds served as good reducing agents, among which propene and 2‐propanol were the most efficient ones. In2O3‐doped Ga2O3–Al2O3 catalyst was capable of reducing NO into N2 quite efficiently in the presence of H2O at a very high space velocity.