Synthesis of titanium hydroxide nanoparticles in supercritical carbon dioxide on the pilot scale

Titanium tetra-isopropoxide (TTIP) hydrolysis in supercritical carbon dioxide (SC-CO2) was performed using a continuous pilot plant with an internal volume of 5 dm3, operated at mild pressure conditions (8–14 MPa) and in the temperature range 40–60 °C. Preliminary to reaction experiments, some tests on TTIP solubility in SC-CO2 were performed. TTIP solubility varies from 1.5 to 3.0% (w/w) in the range 40–60 °C and for pressures between 10 and 15 MPa. Titanium hydroxide nanospheres with a diameter ranging from about 70 to 110 nm and surface areas larger than 300 m2 g−1 were obtained. The influence of the process temperature and pressure on particle morphology, particle size and surface area was studied.