气相吸附法制备复合载体TiO_2/γ-Al_2O_3及TiO_2在γ-Al_2O_3表面的分散状态

Preparation of Complex Support TiO2/γ-Al2O3 by Gas Phase Adsorption and State of TiO2 on γ-Al2O3 Surface

采用气相流动吸附法,以N_2为载气携带TiCl_4通过γ-Al_2O_3床,使TiCl_4吸附在γ-Al_2O_3表面上,经水解、干燥和焙烧制得TiO_2/γ-Al_2O_3复合载体。用XRD,LRS和TEM等表征手段研究了TiO_2在γ-Al_2O_3表面上的分散状态。结果表明,TiO_2在γ-A1_2O_3表面有一分散阈值(0.168 g TiO_2/g γ-Al_2O_3,在阈值以下TiO_2以单层或亚单层分散形式存在,在阈值以上则出现晶相,未发现有体相化合物生成。测定了TiCl_4穿透曲线和吹扫曲线,为用气相流动吸附法制备TiO_2/γ-Al_2O_3复合载体工艺条件的选择提供了基础。

This paper suggests a method to make a highly dispersed complex support with a desirous TiO2 loading. The preparation of TiO2/γ-Al2O3 complex support was carried out as follows: TiC4 was adsorbed onto the surface of γ-A12O3 using N2 as a carrier to obtain a TiCl4/γ-Al2O3 precursor. This was followed by hydrolyzing, drying and calcinating at certain temperatures. The state of TiO2 on the surface of γ-A12O3 was investigated by XRD, LRS and TEM. A dispersion threshold of TiO2, 0. 168 g TiO2/g γ-A12O3, was obtained. As long as the TiO2 content is less than this value, TiO2disperses onto the surface of γ-Al2O3 to form a monolayer or submonolayer; crystalline TiO2 appears when this value is exceeded. No evidence supporting the formation of bulk compounds was found. Both breakthrough curve and blowing out curve of TiCl4 were experimently drawn up, and which are of significance for the study on the kinetic adsorption of TiCl4 on the surface of γ-Al2O3.