低温等离子体协助B_2O_3/γ-Al_2O_3 选择催化还原NO(英文)

Cold Plasma-Assisted Selective Catalytic Reduction of NO over B_2O_3/γ-Al_2O_3

研究了低温等离子体协助催化条件下甲烷选择性催化还原NO反应(SCR).反应气体经等离子体活化后,生成NO2,HCHO,CH3NO和CH3NO2等活性更高的中间产物.程序升温表面反应表明,这些中间产物可在等离子体后置催化装置上进一步反应,从而使NOx还原为N2.在考察的一系列催化剂(包括γ-Al2O3,Ag/γ-Al2O3,B2O3/γ-Al2O3,Ga2O3/γ-Al2O3,In2O3/γ-Al2O3等)中,B2O3/γ-Al2O3表现出最好的催化活性.当反应温度为300oC时,NOx转化率达到最高.与γ-Al2O3催化剂相比,在10wt%B2O3/γ-Al2O3催化剂上,300oC时,NOx转化为N2的转化率从33.4%提高至51.0%.催化剂的酸性对于经等离子体活化后的反应气体在催化剂上的SCR反应起到重要作用.同时,催化剂上吸附态NOx对于NOx的转化也起到一定作用.

A plasma-assisted catalytic system for the selective catalytic reduction of NO with methane was investigated.NO2,HCHO,CH3NO,and CH3NO2 were the reactive intermediates generated by the plasma.The further reactions of these intermediates on the catalyst during the thermal catalytic stage resulted in the conversion of NOx to N2,which was verified by temperature-programmed surface reaction characterization.B2O3/γ-Al2O3 was the best catalyst with the maximum conversion of NOx to N2 increasing from 33.4% on γ-Al2O3 to 51.0% on 10 wt% B2O3/γ-Al2O3 at 300 oC.NH3-TPD characterization showed that the acidity of the catalyst is important for the reduction of NOx by the intermediates generated by the plasma.NOx-TPD showed that the adsorbed NOx species on the catalysts also played a role in the conversion of NOx.