Sn/Al_2O_3催化剂结构与选择性催化还原NO性能

Structure of Sn/Al_2O_3 Catalyst and Its Activity for Selective Catalytic Reduction of NO

以不同沉淀剂和铝盐与SnCl4共沉淀制备了Sn/Al2O3催化剂.考察了催化剂在富氧条件下催化丙烯选择性还原NO的性能,借助于X射线衍射（XRD）、扫描电镜（SEM）、N2吸附-脱附、吡啶吸附红外光谱（Py-IR）和程序升温还原（TPR）等方法研究了催化剂性能与结构的关系.发现以NH3.H2O和NH4HCO3为沉淀剂、NH4Al（SO4）2为铝盐制备的Sn/Al2O3催化剂催化活性最高,NO转化率达90.9%,最佳催化活性温度为350℃.该催化剂的比表面积为254 m^2/g,孔体积为0.878 cm^3/g,孔径分布曲线在3-8 nm出现双峰,Sn物种主要以晶态SnO2存在,且表面Lewis酸酸量增加.

A series of Sn/Al2O3 catalysts were prepared by co-precipitation of SnCl4 and an aluminum salt using different precipitants. The catalyst activity for the selective catalytic reduction of NO by propylene in excess oxygen was investigated. The relationship between the catalytic property and the structure of the Sn/Al2O3 catalysts was explored using X-ray powder diffraction, scanning electron microscopy, N2 adsorption-desorption, infrared spectroscopy of adsorbed pyridine, and temperature-programmed reduction. The results indicated that over the Sn/Al2O3 catalyst prepared using NH3·H2O and NH4HCO3 as the precipitants and NH4Al（SO4）2 as the aluminum source, NO conversion was the highest （90.9%） at 350 ℃ and the optimal catalytic temperature was lowered to 350 ℃. The specific surface area and the pore volume of this catalyst were 254 ma^2/g and 0. 878 cm^3/g, respectively. Distribution of pore size lied in the range of 3 - 8 nm, and dual-peak nano-structure was observed. Most of Sn species existed as crystalline SnOa. The introduction of NH4Al （SO4）2 increased the amount of Lewis acidity of the catalyst.