Photocatalytic properties of titania pillared clays by different drying methods

Photocatalysts based on titania pillared clays (TiO2 PILCs) have been prepa red through a sol-gel method. Different drying methods, air drying (AD), ai r drying after ethanol extraction (EAD), and supercritical drying (SCD) hav e been employed and found to have significant effects on the photocatalytic efficiency of the resultant catalysts for the oxidation of phenol in water . Titania pillared clay (TiO2 PILC) obtained by SCD has the highest externa l and micropore surface area, largest amount and smallest crystallite size of anatase, and exhibited the highest photocatalytic activity. Furthermore, silica titania pillared clay (SiO2-TiO2 PILC) after SCD, titania coated Ti O2 PILC (SCD) and SiO2-TiO2 PILC (SCD) were synthesized to study the key fa ctors controlling the photocatalytic activity. It is concluded that the dis persion of nanometer-sized anatase on the surface of the PILC particles and the suspensibility of the particles are the most important factors for hig h photocatalytic efficiency. (C) 1999 Academic Press.