Rationale for development of high surface zirconium hydroxide: Synthesis route and mechanism discussion

Abstract

In this work, xerogels of zirconium hydroxide were synthesized by the CDJP method at constant pH values from 3 to 8. The effect of precipitation pH and treatment conditions on the properties of xerogels was studied. It was found that all unwashed xerogels contain zirconium-bound nitrate ions and their amount systematically decreases as the precipitation pH increases. A high content of zirconium-bound nitrate ions cause the formation of Brønsted acid sites due to olation/oxolation processes which results to decrease in the specific surface. Washing and hydrothermal treatment have a greater effect on the surface properties of xerogels compared to the precipitation pH. Removal of zirconium-bound nitrate ions provides a significantly increase in the specific surface (up to 580 m2/g). Meanwhile hydrothermal treatment without washing leads to decrease in specific surface. The formation mechanisms of the high surface zirconium hydroxide xerogels was proposed and discussed.