The Preparation And Doption Of Nanometer TiO₂ And Their Uses In The Reaction Of Isomerization

At present, the size distributions of TiO2 powders prepared by hydrolyzing is always wide. The uses of TiO2 are almost focus on the aspect of protection of environment. In this article, we studied the method of preparing narrow distributed TiO2 and dopted TiO2 nanometersized powders and their applications in the rearrangement reaction. Especially , the rearrangement reaction (also named isomerization) of converting styrene oxide to phenylacetyldehyde were investigated.At first, the method of preparing nanometer TiO2 by the hydrolyzing Ti(SO4)2 was investigated. Low cost, simple technology were the obvious advantages of the preparation of the nanometer TiO2 by the hydrolyzing Ti(SO4)2. But in the reported articles, the optimal rate of hydrolysis was only 21.3%. In the ameliorated experiment, we add ethyleneglycol monomethyllether in Ti(SO4)2 solution, and drop saturated NH4HCO3 solution, the rate of hydrolyzing Ti(SO4)2 could be improved to almost 100% and the diameter of the particle TiO2 was reduced.For the more, to enhance the catalytic activity of TiO2, modifications have been introduced to the crystalline matrix by selective doping of oxide. By dropping the Na2SiO3 solution to the hydrolyzing Ti(SO4)2 solution, also add ethyleneglycol monomethyllether, the nanometer TiO2-SiO2 particles were prepared by jelling, baking, calcine. Nanometer TiO2-SnO2 have been prepared from SnCl4?5H2O and Ti(SO4)2 by an activated surface method.The optimal conditions of the preparation of catalysts were studied. The size, size distribution, appearance and composition of the catalysts were observed by XRD, XPS, TEM, EDS, IR, ZETASIZER. The results showed that the sizes of dopants were reduced, and the size distributions were narrowed. This paper selected the ismerization reaction of styrene oxide as characterization of catalytic performance.The reaction mechanism was described in accordance with the general reaction mechanism reported in literatures. Yield of phenylacetyldehyde was measured. The reactin condition such as temperature, time, the polarity of solvent, the activity of acid-base and the composition of catalysts were studied preliminarily. It is suggested that the catalytic activities of doping TiO2 increased. When the mol proportion of TiO2 and SiO2 is 1:3, yield of phenylacetyldehyde is highest, that is 98.2%. When the proportion of weight of TiO2 and SnO2 is 4:1, yield of phenylacetyldehyde is highest, that is 92.6%.