Design and evaluation of photocatalytic micro-channel reactors using TiO2-coated porous ceramics

Photocatalytic micro-channel reactor was designed by exploiting porous ceramic disks as a support for TiO2 photocatalyst. Ethanol solution of titanyl(IV)acetylacetonate and a commercial titania sol were used as the starting materials for the synthesis of TiO2 layer. A rougher surface of the TiO2 channel was prepared from titanyl(IV)acetylacetonate solution by comparing with that from a titania sol. Photocatalytic activity of the micro-channel reactor at various circulation velocities was evaluated by measuring the decay of absrobance of methylene blue aqueous solution. Since the porous disks prepared with the titania sol showed a higher photocatalytic activity at medium flow rates, the surface roughness of the TiO2 was found to decrease the activity. A stagnation region near the rough surface may expand at higher flow rates and then the mass transfer between the TiO2 surface and the laminar flow was suppressed for the reactant molecules and decomposition intermediates.