Mn负载量对nMnOx/TiO2催化剂NH3-SCR催化性能的影响  

Effect of Mn Loading on Catalytic Performance of nMnO/TiO in NH-SCR Reaction

作　　者：杨洋 胡准 米容立 李丹 张涛 刘坤峰 杨会娥 YANG Yang;HU Zhun;MI Rong-li;LI Dan;ZHANG Tao;LIU Kun-feng;YANG Hui-e(Institute of Industrial Catalysis,School of Chemical Engineering and Technology,Xi'an Jiaotong University,Xi'an 710049,China;Sinwochem Molernu Environmenlul Protection Chericals(Xi'un)Co.LTD.,Xi'un 710201,China)

机构地区：[1]西安交通大学化学工程与技术学院,陕西西安710049 [2]中化近代环保化工(西安)有限公司,陕西西安710201

出　　处：《分子催化》2020年第4期313-325,I0002,共14页Journal of Molecular Catalysis(China)

基　　金：国家自然科学基金(21802107);陕西省自然科学基金(2017JQ2016)。

摘　　要：MnOx/TiO2催化剂由于具有优异的低温脱硝性能,已成为SCR催化剂的研究热点之一.我们通过浸渍法制备了一系列不同Mn负载量的nMnOx/TiO2(n=2.5%,5%,10%,15%)(质量分数)催化剂,考察Mn负载量对催化剂脱硝性能的影响.利用N2物理吸附,X-Ray Diffraction(XRD),Scanning Electron Microscope(SEM),Temperature Programmed Reduction with H2(H2-TPR),Temperature Programmed Desorption with NH3(NH3-TPD)和X-Ray Photoelectron Spectroscopy(XPS)对其结构进行表征.结果表明,催化剂的脱硝性能随着Mn负载量(2.5%~15%)(质量分数)的变化呈现"火山型"曲线,当Mn负载量为10%(质量分数)时,催化剂的脱硝性能最佳.H2-TPR和XPS结果表明nMnOx/TiO2催化剂上表面氧比例和表面Mn4+浓度均随着Mn负载量的增大,先增大后减小,具体顺序为10MnOx/TiO2>15MnOx/TiO2>5MnOx/TiO2>2.5MnOx/TiO2,与脱硝性能顺序完全一致.进一步关联表面氧的比例与T50发现,催化剂的表面氧的比例与T50呈线性关系,即表面氧比例越高,T50越小,脱硝活性越高.NH3-TPD结果表明,弱酸酸量的增加有助于低温脱硝活性的提高.这些结果揭示了Mn负载量影响脱硝性能的作用规律,为今后开发高效的锰基低温脱硝催化剂提供了技术支撑.A series of nMnOx/TiO2(n=2.5%,5%,10%and 15%)(Mass percentage)catalysts with different Mn loadings were prepared through impregnation method to investigate the effect of manganese loading on the selective catalytic reduction(SCR)of NO with NH3.The physicochemical properties of nMnOx/TiO2 catalysts were characterized by N2 physisorption/desorption,X-ray Diffraction(XRD),Scanning Electron Microscope(SEM),Temperature Programmed Reduction with H2(H2-TPR),Temperature Programmed Desorption with NH3(NH3-TPD)and X-ray Photoelectron Spectroscopy(XPS).The catalytic activities for the SCR reaction on nMnOx/TiO2 catalysts first increased and then decreased with increasing the manganese loading,showing"volcano"type,maximum at the manganese loading of 10%(Mass percentage).N2 physisorption/desorption and XRD results indicated that all the catalysts showed similar texture properties.H2-TPR results indicated that the amount and property of surface oxygen were highly dependent on the manganese loading.Moreover,the molar ratio of surface oxygen was linear relationship with the catalytic activity(T50),suggesting that the surface oxygen played a crucial role on the SCR activity.XPS results showed the variation in surface oxygen was attributed to the surface Mn4+molar ratio.Meanwhile,NH3-TPD results indicated that the amount of weak acidity could also affect SCR activity.All these results provided a guideline for the development of superior SCR catalysts.

关 键 词：SCR催化剂 锰基催化剂 Mn负载量 表面氧比例 脱硝 

分 类 号：O643.32[理学—物理化学]