Production of Synthesis Gas from Methane Using Lattice Oxygen of NiO−Cr₂O₃−MgO Complex Oxide

Abstract

To produce nitrogen-free synthesis gas or hydrogen by the partial oxidation of methane using air as an oxidant, NiO−Cr2O3−MgO complex oxide was proposed as an effective one. Lattice oxygen of NiO in the complex oxide was effectively transferred to CH4 to give H2 and CO in the ratio of 2−3:1 at 700 °C. NiO was reduced to metallic Ni during the course of the reaction with CH4, and the reduced Ni was successfully oxidized to NiO with air at 700 °C. Repeated cycles of the reaction and oxidation were carried out without any loss of activity. The role of Cr2O3 seemed to weaken the Ni−O bond in NiO−MgO complex oxide, in which NiO is less reducible with CH4 at 700 °C. In addition, the surface oxidation state of Ni was increased to Ni3+ with Cr2O3.