Varying the Conditions of ZrO2⋅nH2O Precipitation and Aging as a Way of Controlling the Phase Composition and Texture of ZrO2

The effect of the precipitation mode, temperature, and ZrO2⋅nH2O aging time on the porous texture, phase composition, and thermal transformations of ZrO2⋅nH2O and ZrO2 has been studied. It has been found that varying the mode of precipitation allows changes in the specific surface area, pore volume, and average pore size of ZrO2⋅nH2O and ZrO2; an increase in the contribution from mesopores to the pore space of ZrO2⋅nH2O; and a change the ZrO2 particle size. It has been shown that raising the temperature of ZrO2⋅nH2O aging results in intense development of the mesoporous structure, an increase in the specific surface area of ZrO2⋅nH2O and ZrO2, and a reduction in the size of ZrO2 particles. At the same time, the ratio of the ZrO2 phases undergoes a nonmonotonic change upon an increase in the period of aging. The selection of the conditions of precipitation and aging allows us to double the pore volume of ZrO2, relative to the respective parameter of a sulfated zirconia isomerization catalyst and increase the surface area without introducing additional components. The best characteristics of the pore structure of ZrO2 (Ssp = 140 m2/g and Vpore = 0.404 cm3/g) are achieved with precipitation at a constant pH value and subsequently aging ZrO2⋅nH2O for 12 h at 90°C.