Comparative Studies on Catalytic Conversion of CO 2 into Olefin with Hybrid Catalysts and Fischer-Tropsch Synthesis Catalysts

One-step conversions of CO2 into olefins were investigated over conventional Fischer-Tropsch synthesis(FTS) catalyst and the new hybrid catalysts. The hybrid catalyst was consisted of methanol synthesis catalyst(Cu/ZnO/Al2O3, Cu/ZnO/ZrO3) and methanol to olefin(MTO) catalyst(Mg-La/ZSM-5). The activity of hybrid catalytic system, which was mixed with Cu/ZnO/Al2O3(6:3:1 in weight ratio) and Mg-La-ZSM-5, was superior than others in terms of CO2 conversion and total hydrocarbon yield, but olefin was not produced significantly. The reason was supposed to be caused by Cu-support interaction, which gives rise to the loss of strong Bronsted acid site and consequently the medium strength acid site production. In contraryto hybrid system, the modified F-T catalytic system showed similar enhanced CO2 conversion. However, it showed high selectivity to olefin. When ZSM-5 was used as a support for Fe-K catalyst system, the selectivity of olefin was found to be increased. The addition of potassium promoters give rise to increase amount of CO2 uptake on the surface, and the improvementof stability in adsorbed Fe-C species. Consequently, by carefully selecting the support and additives on modified F-T catalyst system, it was possible to obtain the high CO2 hydrogenation activity as well as high olefin selectivity.