关键词: Pt/Al₂O₃催化剂, 浸渍, 溶胶-凝胶, NO_x, NO选择性还原

Abstract: Pt-Al₂O₃ is an excellent catalyst for selective catalytic reduction nitrogen oxide at a lower temperature in the presence of oxygen. A series of Pt-Al₂O₃ catalysts with various platinium loadinds were prepared by the sol-gel(SG) and impregnation(IM) methods and the selective catalytic reduction activity of NO with propene(C₃H₆) as the reductant in the presence of excess oxygen was investigated in a fixed-bed microreactor. The results show that Pt-Al₂O₃ has a high activity. Based on the preparation method used in this paper, the optimal Pt loading in mass fraction is 0.35% for IM and 2% for SG respectively; the relationships between the activities over these catalysts and the reaction temperature and the concentrations of reactants and the operation condition were studied respectively. The increase of the C₃H₆ concentration and O₂ concentration in a certain range both promoted the reduction of NO, the optimal oxygen mass fraction is about 8%. The presence of 0.009% SO₂ decreases the catalytic activity, but the ability of resistance SO₂ of 2%Pt-Al₂O₃(SG) is better than 0.35% Pt-Al₂O₃(IM), 10% water present in the feed can enhance the catalytic activity above 250 ℃, and promoted the selective catalytic reduction of NO_x over a wide window(200—450 ℃).

Key words: Pt-Al₂O₃ catalyst, Impregnation, Sol-gel, NO_x, NO selective reduction