Preparation of porous spherical ZrO2–SiO2 composite particles using templating and its solid acidity by H2SO4 treatment

Porous ZrO2–SiO2 composite sphere particles were prepared by impregnating precursor solutions into organic monolith particles, with subsequent calcination in air. The porous spheres possessed uniformly sized pores of around 10 nm. Addition of SiO2–ZrO2 decreased the ZrO2 crystallinity and increased the specific surface area. The acid amount on the surface of the composite spheres was increased by treatment with H2SO4. The acid strength and its amount, including the Lewis/Bronsted acid ratio, depended on the SiO2/ZrO2 ratio and the H2SO4 concentration. The powder treated under an optimum condition exhibited higher solid acidity than the reference solid acid catalyst. The prepared porous SO4 2−/ZrO2–SiO2 spheres showed higher saccharization activity than the reference solid acid catalyst did.