Effect of Sulfate Anion Additions on the Phase Composition and Structure of Titanium Dioxide

Abstract

Methods of X-ray diffraction analysis, electron microscopy, and microanalysis were used to examine the phase composition and structure of sulfate-anion-containing titanium dioxide samples into which a modifier was introduced by impregnation and by the sol-gel technique. It was demonstrated that the modification of titanium dioxide by the impregnation method results in that an ordered surface structure is formed, which is constituted by accreted crystallites 8–10 μm in size. In this structure, sulfate anions are stabilized at interblock boundaries. Titanium dioxide modified by the sol-gel method has the form of loosely packed coarse aggregates with sizes of about 30–32 μm. The appearance of the titanium tetrasulfide phase mostly situated on the surface was observed in its composition. The microstructural features and, in particular, enrichment of the surface of a sol-gel sample with sulfur and a decrease in dispersity are determined by the catalyst preparation conditions.