Pt/Al_2O_3催化剂用于丙烯选择性还原NO

Application of Pt-Al_2O_3 Catalyst in Selective Catalytic Reduction of Nitrogen Oxide by Propene

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 NOx 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 NOx 性能的影响 ,催化活性随丙烯浓度的增大而上升 . 2 % Pt/ Al2 O3( SG)催化剂的抗 SO2性能好于 0 .5% Pt/ A l2 O3( IM)催化剂 ,H2 O的存在可明显拓宽活性温度范围 ,并向高温区间移动 ,在 2 0 0～4 0 0℃范围内可有效净化 NOx.

Pt-Al 2O 3 is an excellent catalyst for selective catalytic reduction nitrogen oxide at a lower temperature in the presence of oxygen. A series of Pt-Al 2O 3 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(C 3H 6) as the reductant in the presence of excess oxygen was investigated in a fixed-bed microreactor. The results show that Pt-Al 2O 3 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 C 3H 6 concentration and O 2 concentration in a certain range both promoted the reduction of NO, the optimal oxygen mass fraction is about 8%. The presence of 0.009% SO 2 decreases the catalytic activity, but the ability of resistance SO 2 of 2%Pt-Al 2O 3(SG) is better than 0.35% Pt-Al 2O 3(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 ℃).