Rapid synthesis of homogeneous titania-silica composite with high-BET surface area

Abstract

We rapidly synthesized a homogeneous titania-silica composite with properties desired by the paper and paint industries by the sol-gel method in a controlled manner. The composite was synthesized by impregnating TiOCl 2 (titania precursor) into preformed silica networks (SiO 2 trimers). The first step before the formation of high molecular weight polymers in this rapid, versatile, and reproducible method involves the generation of trimers of SiO 2 after the rapid condensation of silicic acid monomers. The latter were formed as a product of the reaction of aqueous sodium silicate solution (SiO 2/Na 2O = 3.24) with 2 N HCl. In the second step, TiOCl 2 was added to the SiO 2 trimers at 50 °C. The structure of the composite was characterized by FE-SEM, EDS, TEM, XRD, FTIR, and nitrogen physisorption studies. The results demonstrated the homogeneous incorporation of titania into silica, which is normally difficult to perform because of the significant differences between the hydrolysis rates of the precursors. The maximum BET surface area, average diameter of the pores, and the maximum pore volume obtained were 739 m 2/g, 27.4 Å, and 0.29 cm 3/g respectively. The composite has superior oil absorption (240 ml/100 g) compared to that of the conventional pure TiO 2 (100 ml/100 g) filler. It also shows significant photocatalytic ability. The materials prepared via the proposed method are potential candidates for large scale commercial production.