Effect of crystallite size on the surface defect of titania prepared via solvothermal synthesis

Abstract

This thesis is aimed to investigate the dependence of crystallite size of titania on the surface defect on titania synthesized by solvothermal method for photocatalytic decomposition of ethylene. The characteristics of all the prepared catalysts were characterized using BET surface area, X-ray diffraction spectroscopy (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), temperature programmed reduction (TPR), and hydrogen chemisorption. It was found that photocatalytic activity strongly depended on the crystallite size of titania. Increasing the titania crystallite size from 9 to 15 nm resulting in higher amount of surface defect on titania hence the photocatalytic activities increased. In addition, the catalytic behaviors of various TiO2-supported cobalt catalysts (5, 10, 15 and 20 wt% cobalt loadings) for Fischer-Tropsch synthesis or CO hydrogenation at (H2/CO = 10/1) was also studied. It is revealed that catalyst reducibilities and activities of Co/TiO2 catalysts increased with increasing crystallite size of titania supports. The appropriate cobalt loading was determined to be 10 wt%. Moreover, the selectivities for long chain hydrocarbons were substantially increased with increasing the crystallite size of titania supports.