Surface and acidic properties of mixed zirconium and titanium oxides

he surface and acidic properties of mixed sulfated zirconium and titanium oxides were investigated in the present study. One mode of preparation was followed entailing the use of zirconium sulfate and titanium oxysulfate as starting materials in a 1:1 ratio, and ammonium hydroxide as a precipitating agent. The resulting oxides were subjected to different extents of washing with water to vary their sulfate content. The mixed oxides were then analyzed by nitrogen adsorption, infrared spectroscopy, differential thermal analysis, thermogravimetric analysis, and elemental analysis for sulfur content. The number of acidic sites was determined from the saturation values of the adsorption isotherms of sodium hydroxide. The presence of sulfate groups is found to be the crucial parameter in generating acidity in the mixed zirconium and titanium oxides. A striking feature observed in the present work is the significant increase in acidity in conjunction with the appearance of chelated sulfato ligands in the oxides. Textural analysis of the nitrogen adsorption isotherms and as plots reveal a predominance of a mixture of micropores and mesopores. Observed extents of surface areas do not directly correlate with the surface acidic properties. Sulfate groups appear to have a pore blocking effect leading to drastic decreases in surface areas