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

In the present study, differences in characteristics and catalytic activity towards CO hydrogenation of Co catalysts dispersed on the various B modification on zirconia supports were investigated. After calcination, the various samples were characterized using XRD, SEM/EDX, TEM, TPR and H2 chemisorption. CO hydrogenation (H₂/CO = 10/1) was also performed to determine the overall activity and selectivity. The B modification on zirconia supports was found to increase the catalytic activities of Co catalyst (20 wt%) during CO hydrogenation. The amounts of B loading in the zirconia support were in the range of 0.5 to 3 wt%. The increased activities were attributed to the larger number of reduced Co metal surface atoms for catalyzing the reaction. It is worth noting that B modification can result in (i) preventing the agglomeration of Co oxide species, and (ii) increasing the dispersion of Co oxide species leading to facilitating the reduction of Co oxide species into Co metal surface atoms. In addition, only a slight decrease in C₂-C₄ selectivity was observed. For the various cobalt loading ( 5 to 20 wt%) on the 1 wt % of boron modification on zirconia, it was found to decrease the catalytic activity with decreasing the amount of cobalt loading, but an increase in C₂-C₄ selectivity was observed.