Prudius S. Synthesis and physico-chemical properties of superacid tungstated zirconia

The subject of study: is the influence of synthesis conditions on the activity of WO3/ZrO2 catalysts and the nature of acid sites on the surface. The goal of the study: development of new methods of synthesis of tungstated zirconia with superacid properties and high specific surface area, and also research of its activity in a number of reactions of heterogeneous acid catalysis. Methods of investigation: X-ray phase analysis, UF-Vis reflectance spectroscopy, IR spectroscopy, derivatography, temperature-programmed desorption mass spectrometry, adsorption and catalytics experiments. The improved method for synthesis of tungstated ZrO2 in conditions of controllable hydrolysis of ZrOCl2 and method for synthesis of mesoporous WO3/ZrO2 using polyvinyl alcohol as a template have been proposed. A research has been made into the influence of conditions of synthesis on the specific surface, porous and crystal structure of these systems. It is determined, that in superacid samples WO3/ZrO2 there is tetragonal phase of zirconia, and WO3 clusters on a surface are characterized in the values of forbidden zone equal to 3.0-3.2 eV. The scheme has been proposed for the structure of the acid sites on the surface of WO3/ZrO2. It is shown, that bifunctional WOх/ZrO2(Pt) catalysts show high activity in the reaction of isomerization of n-hexane. The activity of WO3/ZrO2 catalysts has been investigated in the reaction of alkylation of isobutene with ethanol and in the reaction for vapour phase nitration of benzene with nitric acid.