In this present study, the spherical silica support was synthesized from tetraethyloxysilane (TEOS), water, sodium hydroxide, ethylene glycol and n-dodecyltrimethyl ammonium bromide (C₁₂TMABr). The particle size was controlled by variation of the ethylene glycol co-solvent weight ratio of a sol-gel method preparation in the range of 0.10 to 0.50. In addition, the particle size apparently increased with high weight ratio of co-solvent, but the particle size distribution was broader. The standard deviation of particle diameter was large when the co-solvent weight ratio was more than 0.35 and less than 0.15. However, the specific surface area was similar for all weight ratios ranging from 1000 to 1300 m²/g. The synthesized silica was spherical and has high specific surface area. The cobalt was impregnated onto the obtained silica to produce the cobalt catalyst used for CO₂ hydrogenation. The specific surface area was reduced about 50 percentage in rang of 400 to 560 m²/g. Uniformity and good dispersion provided higher efficiency of reactant and product exhibited in the result. The variation of catalyst loading significantly enhanced activity and selectivity of catalyst. The same catalyst loading was found to have a profound influence by uniformity of particle especially for the catalyst efficiency. Moreover, the control of the physical and morphology of support had effect on the performance of Co catalysts in CO₂ hydrogenation.

Thesis (M.Eng)--Chulalongkorn University, 2010