Investigation On Iron-based Catalysts For The Hydrogenation Of Carbon Dioxide To Hydrocarbons

CO₂ hydrogenated to high-added-value hydrocarbons not only contributes to alleviating the rising of atmospheric CO₂ concentration caused by the burning of fossil fuels, but also provides a new route for the synthesis of clean energy. The prospects for this research is great. This work focused on the process of CO₂ hydrogenation to C₅+hydrocarbons over iron based catalyst. The impacts on catalyst activity and hydrocarbon selectivity were analyzed. The main results are shown as follows:1.Fe Si catalysts were prepared by wet-solid-phase grinding. With the increase of SiO₂ content incorporated into iron oxide, the reduction performance of the catalysts became poor, and the degree of crystallinity was weaken. The CO₂ conversion monodirectionally decreased, but the selectivity of C₅+ hydrocarbons is up to 38.6% when the content of SiO₂ was 10% in the catalyst.2.The Fe Si-based catalysts were prepared by coprecipitation method.With the silica content increased, the crystallinity of the catalyst become poor. The incorporation of SiO₂ not only affect the performance of the catalyst reduction and reduction path, but also affect the structure of catalyst carbide. When the content of Silica is 0, the catalyst activity is highest. The incorporation of SiO₂ decreased catalyst activity, but the selectivity of C₅+ hydrocarbons increased at first and then decreased.When the content of silica is 3%, the CO₂ conversion is 14.5%, and the selectivity of C₅+ hydrocarbon is up to 19.8%. Increasing the molar ratio of the reactants H₂/CO₂ favored to improve the catalytic activity of the catalysts.3. The precursor?the silica contents are 3wt% and 5wt%? were prepared by co-precipitation method. The catalysts were made by impregnating with the rare earth metal. The results indicated that the additions of the rare earth metal altered the surface structure of the catalysts. The specific surface area of catalysts decreased, but the pore size became large. The CO₂ conversion was increased, and the CO selectivity decreased.Moreover, the addtion of rare earth metal is beneficial to increase the ability of hydrogenation for the catalysts. Under the same loading content?M/Fe=1%, atomic ratio?, the CO₂ conversion for La-1.0 catalyst is up to11.3%, C₅ + selectivity is 17.4%. Obviously La is the best one among the studied rare earth metal, and its optimum content is La/Fe=0.5%. With the slica contents was 3 wt%, the catalyst?loading 0.5% La, atomic ratio?owned the highest activity and C₅+ selcetivity.