Copper precursor effect on reducibility and titania phases concentration of sol-cel Cu/TiO2 catalyst

Cu/TiO2 catalyst was synthesized by cogelling CuSO4, or CuCl2, with titaniu m ethoxide, Samples were nanocrystalline with titania phase concentration t hat depended on copper precursor and sample annealing temperature. Phase qu antitative analysis was performed by refining crystalline structure. The fr esh samples prepared with CuSO4 contained almost amorphous rutile with an a verage crystallite size of 1,4(1) nm, Average crystallite sizes correlated well to BET areas, which were large for fresh samples and for those calcine d at 400 degrees C, and only a few square meters per gram for those calcine d at 800 degrees C, Hydrogen consumption of the samples prepared with CuSO4 was 20 times larger than in those prepared with CuCl2, Reduction temperatu re and hydrogen consumption, which are determined by copper-titania interac tion, can be explained in terms of the main defects found in nanocrystallin e titania phases: titanium vacancies and hydroxyls in their crystalline str ucture. (C) 1999 Academic Press.