Large-scale production of titania nano-coated silica-gel beads by fluidized bed chemical vapor deposition

A new technique of thermal fluidized-bed metal-organic chemical vapor deposition (FB-MOCVD) was developed to prepare titania nano-coated silica-gel beads on a large scale (20 kg/batch) at different deposition temperatures of 450, 500, 550, and 600°C. Titanium tetra iso-propoxide (TTIP, Ti[OCH(CH3)2]4, Aldrich Chemical Co.) was used as a precursor of titania. The titania nano-coated silica-gel beads prepared by FB-MOCVD apparatus were hardly breakable compared to other common coating techniques in liquid phase such as sol-gel and dipping method. It was found that, from the FE-SEM/EDXS analysis and XPS results, the surfaces of silica-gel beads were covered with particle forms of titania. The photocatalytic degradation of acetaldehyde into CO2 and H2O was not much affected by deposition temperature.