Preparation of porous titania particles by partial dissolution and hot-water or hydrothermal treatment of hydrous titania

Uniform-sized amorphous hydrous titania particles (HTPs) with nonporous or porous surface were prepared and subjected to hot-water or hydrothermal treatment to induce crystallisation of the titania phase for preparing porous titania particles with high specific surface area (SSA) and outer diameter in a micron order. Porous HTPs were crystallised under milder treatment conditions than those required to crystallise nonporous spherical HTPs. This difference was attributed to the difference in the polycondensation states of hydrous titania. The SSA of the porous titania particles crystallised by hot-water treatment at 80°C for 24 h was 216 m² g⁻¹, despite their micron-order particle size. This simple method can synthesise highly functional titania particles at low temperatures and is a general-purpose method for preparing porous particles for use as adsorbents, catalysts and catalyst supports.