Copper Precursor Effect on Reducibility and Titania Phases Concentration of Sol–Gel Cu/TiO2Catalyst

Cu/TiO2catalyst was synthesized by cogelling CuSO4, or CuCl2, with titanium ethoxide. Samples were nanocrystalline with titania phase concentration that depended on copper precursor and sample annealing temperature. Phase quantitative analysis was performed by refining crystalline structure. The fresh samples prepared with CuSO4contained almost amorphous rutile with an average crystallite size of 1.4(1) nm. Average crystallite sizes correlated well to BET areas, which were large for fresh samples and for those calcined at 400°C, and only a few square meters per gram for those calcined at 800°C. Hydrogen consumption of the samples prepared with CuSO4was 20 times larger than in those prepared with CuCl2. Reduction temperature and hydrogen consumption, which are determined by copper– titania interaction, can be explained in terms of the main defects found in nanocrystalline titania phases: titanium vacancies and hydroxyls in their crystalline structure.