SO_2对NO催化氧化过程的影响 I.载体的作用

Effect of SO_2 on NO Catalytic Oxidation I. Role of Supports

研究了载体在 SO2 影响 NO催化氧化过程中的作用 ,考察了反应温度为 42 3 K时 ,γ-Al2 O3、Zr O2 、Ti O2 和 Si O2 4种载体及其负载的 Pt催化剂对 NO的氧化性能 ,与 SO2 存在下的 NO反应活性相比 ,只有 γ-Al2 O3及其负载的 Pt催化剂上存在 SO2 促进 NO氧化的现象。运用 BET、XRD、IR及固体酸度测定等多种表征手段 ,对不同载体在反应前后的化学结构和表面性质进行了分析 ,并与反应过程相联系 ,证实 SO2 的吸附改变了γ-Al2 O3的表面结构 ,有利于产物 NO2 的脱附 ;而对 SO2 吸附能力较弱的其他载体或催化剂 ,SO2

The role of supports in the catalytic oxidation of NO to NO 2 in the presence of SO 2 was studied. The catalytic activities of four kinds of supports γ Al 2O 3, ZrO 2, TiO 2 and SiO 2 as well as the Pt catalysts supported on them were investigated for the NO oxidation at the reaction temperature 423K. The promoting effect of SO 2 on the oxidation was observed over γ Al 2O 3 and Pt/ γ Al 2O 3 only by comparing the reaction with and without SO 2. The chemical structures and surface properties of different supports berfore and after reaction with SO 2 were analyzed using BET, XRD, IR and solid acid detection methods. The results suggest that the adsorption of SO 2 on the surface of γ Al 2O 3 is responsible for SO 2 promotion due to the modification of SO 2 ad species on the support surface. In the cases of other supports and catalysts, however, the adsorption of SO 2 over them is relative weak, thus the promoting effect of SO 2 could not be exerted.