Effects of modified SiO2 on H2 and CO adsorption and hydrogenation of iron-based catalysts

Metal-modified SiO2 supports were prepared by sol-gel method with Mn, Zn, Zr, and Sr cations doping, and then iron-based catalysts supported on modified SiO2 were prepared by the impregnation method. The iron-based catalysts were characterized by XRD, N2 adsorption, and XPS. The reduction adsorption property of H2 and hydrogenation property of CO were studied by temperature programmed methods. The interaction between catalyst and H was studied by kinetic analysis. The results indicate that metal modification has no influence on phase composition of Fe and surface electronic state of Fe species. However, the modification reduces surface area of catalyst and dispersion of active phase, weakens adsorption ability of H2 and lowers H2 desorption activation energy of the catalyst. Zn and Zr doping restrain reduction of catalysts, while Mn and Sr doping promotes reduction of catalysts. The doping of Mn, Zn and Zr inhibits adsorption of CO on the catalyst surface, while Sr promotes dissociation and adsorption of CO. Mn, Zn, Zr and Sr promote C°C coupling and hydrogenation reaction. Among them, Mn and Zr are more prominent.