Effects of MgO promoter on properties of Ni/Al2O3 catalysts for partial oxidation of methane to syngas

Abstract

The effects of MgO promoter on the physico-chemical properties and catalytic performance of Ni/Al₂O₃ catalysts for the partial oxidation of methane to syngas were studied by means of BET, XRD, H₂-TPR, TEM and performance evaluation. It was found that the MgO promoter benefited from the uniformity of nickel species in the catalysts, inhibited the formation of NiAl₂O₄ spinel and improved the interaction between nickel species and support. These results were related to the formation of NiO MgO solid solution and MgAl₂O₄ spinel. Moreover, for the catalysts with a proper amount of MgO promoter, the nickel dispersiveness was enhanced, therefore making their catalytic performance in methane partial oxidation improved. However, the excessive MgO promoter exerted a negative effect on the catalytic performance. Meanwhile, the basicity of MgO promoted the reversed water gas shift reaction, which led to an increase in CO selectivity and a decrease in H2 selectivity. The suitable content of MgO promoter in Ni/Al₂O₃ catalyst was ?7 wt-%.