The Effect of MgO Precoating on the Perfomance of Ni/MgO-Al<sub>2</sub>O<sub>3</sub> Catalysts for Carbon Dioxide Reforming of Methane

Abstract

Ni catalysts supported on γ?-Al2O3 supports modified by different MgO precoating weight were prepared by impregnation method. The surface area, pore diameter and Ni crystallite size were investigated by N2 adsorption/desorption (BET) and X-ray diffraction (XRD) methods. The reducing temperature and quantity information of reducible nickel species were obtained by H2-TPR experiments. The CO2 adsorption/desorption abilities of catalysts were investigated and the activity of catalysts were also measured. The coke resistance performance of catalysts for carbon dioxide reforming of methane (CDRM) was studied by CO2 temperature programmed surface reaction (CO2-TPSR). H2-TPR results revealed that there were three kinds of Ni species on the supports. Appropriate modification amount of MgO could increase the surface nickel active sites which could be easily reduced and prevented the formation of NiAl2O4 spinel species. CO2-TPD indicated that the addition of MgO increased the amount of CO2 adsorption at lower temperatures. N2 adsorption/desorption results disclosed that the excessive modification of MgO would decrease the surface area and pore size of the samples. The reforming reaction results showed that the activity was elevated from 58.62% to 65.95% over the Ni/MgO-Al2O3 when the Mg/Al ratio was 0.05 (wt.) and there was less coke evidenced by the CO2-TPSR results comparing to the Ni/γ?-Al2O3 catalyst.