Thorium promoted Co/HMS catalysts were prepared by the co-impregnation method, and the influence of thorium content on structure characterization of Co/HMS was investigated by XRD, TPR, H₂-TPD and TG characterization. It was found that cobalt reducibility was decreased due to the addition of thorium promoter, but kept constant with thorium content of 0.5～5 wt%, then the reduction of cobalt species would be more difficult even with more thorium content. Under the conditions of H₂/CO＝2.0, T＝473～493 K, p＝2.0 MPa, GHSV＝500 h^－1, CO conversion had a trend to increase with the increasing thorium relating to the increasing surface metal cobalt, and maximum CO conversion appeared at about 1.5 wt% of the thorium content, then CO conversion decreased gradually with further increasing thorium due to the coverage of cobalt species by thorium species, and the decreasing cobalt reducibility at high thorium content. The addition of thorium promoted the chain propagation at low reaction temperature, but had little effect on methane selectivity and light hydrocarbon.

Key words: thorium, HMS, cobalt catalyst, Fischer-Tropsch synthesis