High temperature stable mesoporous anatase TiO2 photocatalyst achieved by silica addition

• Published in: Applied catalysis. A, General Vol. 349; no. 1-2; pp. 13 - 19
• Main Authors: PERIYAT, P, BAIJU, K. V, MUKUNDAN, P, PILLAI, P. K, WARRIER, K. G. K
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier 31.10.2008
• Subjects: Catalysis; Chemistry; Colloidal gels. Colloidal sols; Colloidal state and disperse state; Exact sciences and technology; General and physical chemistry; Photochemistry; Physical chemistry of induced reactions (with radiations, particles and ultrasonics); Porous materials; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; Binary compound; Dyes; Anatase; Doping; High temperature; Surface analysis; Titania; Porous material; Precursor; Silica; Photocatalyst; Powder; Pore size; Raman spectrometry; Rate constant; Composition; Photocatalysis; Sol-gel; Transition element compounds; X ray diffraction; Mesoporosity; Methylene blue; Heterogeneous catalysis; Sol gel process; Preparation; Distribution; Surface area; Titanium oxide; Reflectance
• ISSN: 0926-860X; 1873-3875
• DOI: 10.1016/j.apcata.2008.07.022

An aqueous sol-gel method was developed to synthesize a high temperature stable anatase titania photocatalyst by doping with silica. Doping was achieved in titania by the addition of silica sol prepared from tetra ethyl orthosilicate (TEOS). 1, 2, 5 and 15 mol% silica-titania mixed oxide were prepared and characterised by X-ray diffraction, Raman spectroscopy, surface area analysis and diffuse reflectance spectra. Fully anatase phase was obtained at 1000 deg C by the addition of 15 mol% silica. The 15Si-Ti (15 denotes mol% of silica) had a specific surface area of 187.3 m2/g at 500 deg C and it retains a value of 93.0 m2/g at 800 deg C, whereas the undoped one shows 48.7 m2/g at 500 deg C and zero value at 800 deg C. Moreover, the 15Si-Ti composition retains the pore diameter in the mesoporous range (4.6 nm) at this high temperature of 800 deg C. The photocatalytic analysis showed that the system with silica added possessed a higher activity than pure titania. The 15Si-Ti sample calcined at 800 deg C decolourised the methylene blue dye within 30 min (rate constant 0.084 min-1), whereas the undoped sample decolourised the dye after 180 min (rate constant 0.018 min-1). The present method of preparation offers the advantages of inexpensive precursor, homogeneous distribution of the dopant over titania at nano-level and enables control over the powder characteristics of titania.