Al_2O_3-TiO_2复合载体的制备与表征

采用共沉淀法制备了A l2O3-T iO2复合载体,采用BET法、压汞法、扫描电子显微镜、X射线衍射、吡啶吸附-程序升温脱附和吡啶吸附红外光谱法对A l2O3-T iO2复合载体进行了表征。讨论了焙烧温度对A l2O3-T iO2复合载体的比表面积、孔径分布及晶型的影响,观察了A l2O3-T iO2复合载体的形貌,同时对A l2O3-T iO2复合载体的表面酸性进行了研究。实验结果发现,随焙烧温度的升高,A l2O3-T iO2复合载体的比表面积减小、孔体积和平均孔径增大;A l2O3-T iO2复合载体中T iO2的存在降低了A l2O3晶型的转变温度,而A l2O3的存在则升高了T iO2的晶型转变温度,提高了T iO2的热稳定性;A l2O3-T iO2复合载体表面具有较低的酸性,且只有L酸中心;A l2O3-T iO2复合载体为球状微粒。

Preparation and Characterization of Al2O3-TiO2 Complex Support

Al_2O_3-TiO_2 complex support was prepared by co-precipitation and characterized by means of BET,mercury injection method,SEM,XRD,Pyridine-TPD and Pyridine-IR.Effects of calcinations temperature on specific surface area,pore size distribution and crystal transformation were studied.Surface morphology and acidity of the support were also investigated.Increasing of calcination temperature,specific surface area of support declined,and pore volume and average aperture gradually augmented.The presence of TiO_2 could reduce temperature of Al_2O_3 crystal transformation in Al_2O_3-TiO_2 complex support and accelerate the transformation.Due to presence of Al_2O_3 in the complex,TiO_2 transformation temperature rose and its thermal stability improved.Al_2O_3-TiO_2 complex support had low surface acidity and contained only Lewis acid sites.The acid strength order was:Al_2O_3>TiO_2>Al_2O_3-TiO_2.Al_2O_3 possessed much lamellar structure,but Al_2O_3-TiO_2 showed as spherical particulates.