纳米级TiO_2粉体的制备研究Ⅰ.pH值的影响

STUDY OF PREPARATION OF ULTRAFINE TiO2 PARTICLESⅠ INFLUENCE OF pH VALUES

采用无机盐作为前驱物，利用溶胶凝胶超临界流体干燥（ＳＣＦＤ）法，制备出大孔、高比表面纳米级ＴｉＯ２超细粉。详细考察了初始水凝胶ｐＨ值对ＴｉＯ２超细粉形貌、晶相、颗粒大小、比表面积及孔结构等的影响。实验结果发现：当在酸性环境中，所制得的ＴｉＯ２超细粉的比表面积随着ｐＨ值的减小而增大；而在碱性环境中，则随着ｐＨ值的增大而增大。ＴｉＯ２超细粉的比表面积和孔体积由ｐＨ为６．５时的ＳＢＥＴ＝１４２．２ｍ２·ｇ１，ＶＰＮ＝０．４５ｃｍ３·ｇ１，增大到ｐＨ值为１３．０时的ＳＢＥＴ＝４２５．６ｍ２·ｇ１，ＶＰＮ＝１．７９ｃｍ３·ｇ１，且颗粒分布均匀狭窄，颗粒间的三维网络织构更为规整清晰。

Supercritical fluid drying (SCFD) method has been used for the synthesis of ultrafine TiO2 powders with average particle diameter 5￣10nm from titanium tetrachloride These ultrafine powders have high surface areas and large pore volumes The influence of the pH values of the original hydrogel on the textural and structural properties of ultrafine TiO2 powders has been investigated, including the morphology, crystalline phase, particle size surface area, pore structure etc The results of the experiments have shown that the pH values of hydrogel is one of the most important influential factors With the increase of the pH values, very small particles are intimately interlinked so that they seem to form a threedimension network structure in TEM images; the specific surface areas and pore volumes, as its increase from pH=65 to pH=130, change from 1422m2·g1 to 4256m2·g1, and 045cm3·g1 to 179cm3·g1, respectively; and they showed broadened anatase peaks in the XRD profiles