Characterization of silica-supported Ni catalysts effective for methane decomposition by Ni K-edge XAFS

The structural change of Ni species during the methane decomposition into hydrogen and carbon over Ni/SiO₂ catalyst was investigated by Ni K-edge XANES/EXAFS. Before the contact of methane with the Ni/SiO₂ catalyst, Ni species were present as Ni metal mainly. The structure of the Ni metal did not change appreciably when the Ni/SiO₂ was actively decomposing methane. In contrast, the formation of nickel carbide species was observed at the deactivation stage of the catalyst.