Effects of SiO2 modification on the hydrothermal stability of the V2O5/WO3-TiO2 NH3-SCR catalyst: TiO2 structure and vanadia species
Effects of SiO2 modification on the hydrothermal stability of the V2O5/WO3-TiO2 NH3-SCR catalyst: TiO2 structure and vanadia species
复制标题
SiO2 改性对 V2O5/WO3-TiO2 NH3-SCR 催化剂水热稳定性的影响：TiO2 结构和氧化钒物种
DOI：
10.1039/c9cy00385a
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发表时间：
2019
影响因子：
5
通讯作者：
Ma Yue
中科院分区：
文献类型：
--
作者：
Liu Xuesong;Chen Hongfeng;Wu Xiaodong;Cao Li;Jiang Peng;Yu Qifan;Ma Yue
为了考察二氧化硅改性对V2O5/WO3-Ti02催化剂水热稳定性的影响，将催化剂在650℃和750℃的10ol%H2O/空气中水热处理24 h，用氮气物理吸附(BET)、X射线衍射仪(XRD)、透射电子显微镜(TEM)、X射线光电子能谱(XPS)、拉曼光谱(喇曼)、H2程序升温还原(H2-TPR)和NH3程序升温脱附(NH3-TPD)对催化剂进行了表征。根据实验结果推测，Si4+离子进入TiO2点阵会形成SixTi1XO2固溶体，从而抑制了二氧化钛微晶的团聚和锐钛矿型向金红石型的相变。Si掺杂的这些优点可以从根本上提高V2O5/WO3-TiO2光催化剂的水热稳定性。老化后SCR性能的下降是由于大量的比表面积损失和钒物种的进化。我们的观察表明，掺杂的催化剂在650℃以下是稳定的，在750℃的水热老化过程中，催化剂上形成了无活性的VxTi1−xO2相和晶态V2O5。
To investigate the effects of silica modification on the hydrothermal stability of the V2O5/WO3–TiO2 catalyst, the catalysts were hydrothermally treated at 650 °C and 750 °C in 10 vol% H2O/air for 24 h. The fresh and aged catalysts were characterized by nitrogen physisorption (BET), X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy (Raman), temperature-programmed reduction of H2 (H2-TPR) and temperature-programmed desorption of NH3 (NH3-TPD). Based on the experimental results, it is assumed that Si4+ ions enter the TiO2 lattice to form SixTi1−xO2 solid solutions, which could inhibit the agglomeration of titania crystallites and anatase-to-rutile phase transition. These advantages of Si doping can essentially benefit the hydrothermal stability of V2O5/WO3–TiO2 catalysts. The decrease of the SCR performance upon ageing is due to the extensive loss of surface area and evolution of vanadia species. Our observations show that the doped catalysts are stable at temperatures below 650 °C and the inactive VxTi1−xO2 phase and crystalline V2O5 form on the catalysts upon hydrothermal ageing at 750 °C.