Dependence of the Catalytic Activity of Ag/Al2O3 on the Silver Concentration in the Selective Reduction of NOx with n-Hexane in the Presence of H-2

作者：Sadokhina N A^*; Prokhorova A F; Kvon R I; Mashkovskii I S; Bragina G O; Baeva G N; Bukhtiyarov V I; Stakheev A Yu

来源：Kinetics and Catalysis, 2012, 53(1): 107-116.

DOI：10.1134/S0023158412010090

The activity of 0.25-5% Ag/Al2O3 catalysts in the selective catalytic reduction of nitrogen oxides with n-hexane under the conditions of promotion with a small amount of H-2 was studied. It was found that, upon the introduction of similar to 1000 ppm of H-2 into the reaction mixture, the Ag/Al2O3 samples containing 1-2% Ag exhibited optimum activity and selectivity. It was established that, in the presence of 1000 ppm of H-2, the rate of the selective catalytic reduction of NOx was higher by a factor of 10-13, and the onset temperature of the reaction was lower by approximately 100 degrees C. It was found by X-ray photoelectron spectroscopy, temperature-programmed reduction, and UV spectroscopy that the high activity of 1-2% Ag/Al2O3 catalysts was due to the presence of small Ag(n)(delta+)and Ag-m(0) clusters on their surface. A decrease in the concentration of Ag below the optimum value resulted in the predominance of an inactive ionic form on the catalyst surfaces. As the concentration of Ag was increased (>2%), large particles of Ag2O and Ag-0, which facilitate the oxidation of n-C6H14, were formed to lead to a decrease in selectivity and in the degree of reduction of nitrogen oxides.

• 出版日期2012-2