Pt/Al2O3催化剂用于丙烯选择性还原NO

分别采用浸渍法(IM)和溶胶-凝胶法(SG)制备了一系列不同铂负载量的催化剂,在固定床反应器上用C3H6作还原剂,测试了选择性还原NO_x的活性,结果发现,在IM法和SG法制备的催化剂中,活性组分铂最佳负载质量分数分别为0.5%和2%.针对两种催化剂,分别考察了氧浓度、丙烯浓度及反应气流量对选择性催化还原NO_x性能的影响,催化活性随丙烯浓度的增大而上升.2%Pt/Al₂O₃(SG)催化剂的抗SO₂性能好于0.5%Pt/Al₂O₃(IM)催化剂,H₂O的存在可明显拓宽活性温度范围,并向高温区间移动,在200～400℃范围内可有效净化NO_x.

Application of Pt-Al2O3 Catalyst in Selective Catalytic Reduction of Nitrogen Oxide by Propene

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 ℃).