CeO2-TiO2复合氧化物的制备及其表征

本文以廉价的无机盐为原料，采用sol－gel法制备了Ce：Ti（摩尔比）为0．05～0．4：1之间的一系列CeO₂－TiO₂复合氧化物．利用物理吸附仪，XRD，TEM等手段对复合氧化物的织构和结构性质进行了表征．结果发现：采用无机盐－超临界流体干燥法可制备大孔、高比表面积的CeO₂－TiO₂复合氧化物，随着CeO₂含量从5％增加到40％，复合氧化物的比表面积由67．3m²·g^－1增加到219．4m²·g^－1；物相由锐钛矿转变为无定形；粒体的粒径、形貌也随之变化，由颗粒状逐渐变为网络结构．而与超临界流体干燥得到的气凝胶相比；采用普通干燥法制备得到的复合氧化物具有较低的孔体积和比表面积，颗粒间团聚较严重，但无“孤岛”状大颗粒，晶相为无定型结构．

Preparation and Characterization of CeO2-TiO2 Mixed Oxides

CeO₂-TiO₂ oxides were prepared by sol-gel methods from cheap precursors (TiCl₄ and Ce(NO₃)₃) and their morphology, crystalline phase, surface area and pore structure were characterized by BET, TEM and XRD. The results show that the CeO₂-TiO₂ mixed oxides prepared by supercritical fluid drying method (SCFD) have high surface area and large pore volume. With the increase of CeO₂ concentration from 5% to 40% in the CeO₂-TiO₂ mixed oxide, the surface area increases from 67.3m₂·g^-1 to 219.4m²·g^-1, the crystalline phase changes from anatase to amorphous, and the morphology from isolated particle to very small particles interlinked to a three-dimension network structure. But the CeO₂-TiO₂ mixed oxides prepared by conventional drying method show lower pore volume and surface area with serious aggregation, and amorphous phase compared to the corresponding aerogels.