J Environ Sci (China). 2013 Dec 1;25(12):2492-7. doi: 10.1016/s1001-0742(12)60335-0.
This study introduced TiO2-pillared clays (TiO2-PILC) as a support for the catalytic oxidation of NO and analyzed the performance of chromium oxides as the active site of the oxidation process. Cr-based catalysts were prepared by a wet impregnation method. It was found that the 10 wt.% chromium doping on the support achieved the best catalytic activity. At 350 degrees C, the NO conversion was 61% under conditions of GHSV = 23600 hr(-1). The BET data showed that the support particles had a mesoporous structure. H2-TPR showed that Cr(10)TiP (10 wt.% Cr doping on TiO2-PILC) clearly exhibited a smooth single peak. EPR and XPS were used to elucidate the oxidation process. During the NO + O2 adsorption, the intensity of evolution of superoxide ions (O2(-)) increased. The content of Cr3+ on the surface of the used catalyst was 40.37%, but when the used catalyst continued adsorbing NO, the Cr3+ increased to 50.28%. Additionally, O(alpha)/O(beta) increased markedly through the oxidation process. The NO conversion decreased when SO2 was added into the system, but when the SO2 was removed, the catalytic activity recovered almost up to the initial level. FT-IR spectra did not show a distinct characteristic peak of SO4(2-).
本研究介绍了 TiO2 柱撑粘土（TiO2-PILC）作为 NO 催化氧化的载体，并分析了氧化过程中以铬氧化物为活性位的性能。采用湿浸渍法制备了含铬催化剂。结果表明，在载体上掺杂 10wt%的铬时，催化剂表现出最佳的催化活性。在 GHSV = 23600 hr(-1)时，NO 转化率在 350°C 时达到 61%。BET 数据表明载体颗粒具有介孔结构。H2-TPR 表明 Cr(10)TiP（10wt%Cr 掺杂于 TiO2-PILC）明显呈现出平滑的单峰。EPR 和 XPS 被用于阐明氧化过程。在 NO + O2 吸附过程中，超氧离子（O2(-)）的演化强度增加。使用后的催化剂表面的 Cr3+含量为 40.37%，但当使用后的催化剂继续吸附 NO 时，Cr3+增加到 50.28%。此外，通过氧化过程，O(alpha)/O(beta)显著增加。当向体系中添加 SO2 时，NO 转化率降低，但当去除 SO2 时，催化活性几乎恢复到初始水平。FT-IR 谱图中没有显示出 SO4(2-)的特征峰。
