Abstract:

In recent years, with the consumption of fossil resources and the large amount of CO₂ emissions, the energy crisis and the greenhouse question become deeply serious. The direct synthesis of olefins by CO₂ hydrogenation with iron-based catalysts is one of the best ways to achieve CO₂ reduction. In this study, zirconia (ZrO₂)-supported iron-cobalt catalyst (Fe-Co/ZrO₂) and ZrO₂-supported iron-cobalt-potassium catalyst (Fe-Co-K/ZrO₂) were prepared by impregnation method, which were used for CO₂ hydrogenation to light olefins (C₂⁼-C₄⁼), and the effect of K on the catalytic activity were investigated emphatically. At the condition of 300 ℃ and 1.5 MPa, the activity test show that addition of K increases the CO₂ conversion from 40.8% to 44.8%, improves the selectivity of light olefins from 0.23% to 68.5%, and raises the stability of catalytic performance. The characterization results show that introduction of K improves electron cloud density of the iron species, enhances adsorption strength of the Fe to CO₂, promotes the formation of iron carbide, and facilitates direct dissociation of CO₂ after adsorption on Fe species, thus boosts the performance of CO₂ hydrogenation to light olefins.

Key words: CO₂ hydrogenation, light olefin, iron-cobalt catalyst, effect of K