Cold Plasma-Assisted Selective Catalytic Reduction of NO over B2O3/γ-Al2O3

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. B2O3γ-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% B2O3γ-Al2O3 at 300 °C. 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.

摘要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 300 °C 时, NOx 转化率达到最高. 与γ-Al2O3 催化剂相比, 在 10 wt% B2O3/γ-Al2O3 催化剂上, 300 °C 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.

Plasma gas-phase reactions generated NO2, HCHO, CH3NO, and CH3NO2 as active chemicals. Further reactions of these chemicals on the post-plasma B2O3/γ-Al2O3 result in the conversion of NOx.Figure optionsDownload as PowerPoint slide