Characterization of surface processes at the Ni-based catalyst during the methanation of biomass-derived synthesis gas: X-ray photoelectron spectroscopy (XPS) Original Research Article

Surface modifications during the production of methane from reformer synthesis gas over a commercial Ni/Al2O3 catalyst were investigated by quasi-in situ X-ray photoelectron spectroscopy (XPS) and other surface analytical techniques. Experiments of methanation reaction were done in the high pressure cell (HPC) integrated in the XPS system and under fixed-bed conditions. The interaction of the different reformer biomass-derived synthesis gas on the surface properties of the catalyst and on its activity under methanation conditions were studied on a nanoscopic level. Detailed description of changes in metal particle morphology and carbon deposit is presented. A mechanism of C-whiskers formation during long exposure to methanation conditions is described. The role of additional components in the gas mixture, such as CO2, H2O, CH4, C2H4, C2H2, C3H6 and C2H6, were studied in details. Furthermore, role of different nickel compounds such as oxides, hydroxides, carbides and carbonates are discussed.