Thesis (M.Eng.)--Chulalongkorn University, 2007

In this work, the effects of bulk and surface defects on TiO[subscript 2] upports prepared by the sol-gel method were investigated over Co/TiO[subscript 2] catalyst. The 20%wt of cobalt were impregnated onto TiO[subscript 2] having different amounts of bulk and surface defects, which were prepared from the sol-gel method by controlling the water: alkoxide molar ratios during sol-gel synthesis. The Co/TiO[subscript 2] catalysts were characterized with different techniques including XRD, N[subscript 2]-physisorption, SEM, TEM, H[subscript 2]-chemisorption, temperature-programmed reduction (TPR). It showed that the optimum amount of bulk and surface defects can result in high total H[subscript 2] chemisorption, high reducibility, low reduction temperature, and consequently high conversion for methanation of the Co/TiO[subscript 2] catalyst. This was attributed to changes in the SMSI property superimposed with the interaction between cobalt and TiO[subscript 2] support caused by impregnate cobalt onto different bulk and surface defects on TiO[subscript 2].