反应条件对Cu/Al-Ce-PILC上丙烯选择性催化还原NO反应的影响

 采用聚合羟基复合阳离子合成交联黏土Al-Ce-PILC, 经SO2-4改性后,以浸渍法制备了铜基交联黏土催化剂Cu/Al-Ce-PILC, 并将其应用于C3H6选择性还原NO的反应,考察了预处理气氛、 O2和C3H6浓度、空速、水蒸气和SO2等反应条件对催化剂性能的影响. 结果表明, He预处理后催化剂表面的Cu物种以Cu+和Cu2+两种形式存在,而H2预处理后仅以Cu+存在, NO转化率最大值由23%升至56%. 反应体系中适当的O2和C3H6浓度可促进NO还原为N2, 但过高的浓度反而可降低NO的还原活性, O2同时可起到抑制积炭、清洁催化剂表面的作用. NO转化率随着空速的增大而降低. 10%水蒸气的存在可抑制NO的还原和C3H6的氧化,其转化率曲线向高温方向位移. 但是,由于金属氧化物交联柱表面的疏水特性, Cu/Al-Ce-PILC较Cu/ZSM-5具有较强的耐湿热稳定性, NO和C3H6最大转化率仅分别下降13%和5%. SO2的存在明显抑制了催化剂的低温活性,但对高温活性有一定促进作用.

Effect of Reaction Conditions on Catalytic Performance of Cu/Al-Ce-PILC for Selective Catalytic Reduction of NO by Propylene

Montmorillonite was pillared by multi-oligomeric hydroxyl cations to synthesize Al-Ce-PILC(PILCpillared interlayer clay),which was modified by SO~(2-)_4 and then was used as a catalyst support to prepare the Cu/Al-Ce-PILC catalyst by impregnation.The influence of pretreatment atmosphere,concentration of O_2 and C_3H_6,space velocity,water vapor,and SO_2 on the conversion of NO and C_3H_6 over Cu/Al-Ce-PILC was investigated.The results showed that both Cu~ and Cu~(2 ) species were observed on Cu/Al-Ce-PILC pretreated in He,while only Cu~ existed after being pretreated in H_2,and the maximum NO conversion was enhanced from 23% to 56%.Proper concentration of O_2 and C_3H_6 promoted the reduction of NO to N_2,and the formation of coke was distinctly suppressed by excess oxygen.NO conversion decreased with increasing space velocity.The presence of 10% water vapor in the feed restrained the selective catalytic reduction(SCR) of NO,the temperature for the maximum conversion increased,and the maximum conversion of NO and C_3H_6 decreased by 13% and 5%,respectively.Compared with Cu-ZSM-5,Cu/Al-Ce-PILC showed better resistance to water vapor owing to the hydrophobic nature of the oxide pillar surface.SO_2 greatly inhibited the SCR activity of Cu/Al-Ce-PILC at low temperature and slightly promoted it at high temperature.