Coprecipitated NiAl and NiCuAl catalysts for methane decomposition and carbon deposition I. Genesis of Calcined and reduced catalysts Original Research Article

The structure of coprecipitated NiAl and NiCuAl catalyst with high nickel content (60–90 wt.-% Ni-alumina) has been investigated by X-ray powder diffraction, extended X-ray absorption fine structure (EXAFS) spectroscopy and Auger electron spectroscopy of calcined and reduced samples. The alumina was shown to behave as a textural promoter. The model of the reduced NiAl catalyst consisted of highly dispersed nickel and alumina particles with a NiAl spinel phase at their interface. The NiAl spinel phase had mainly an inverse structure. In the reduced sample the paracrystallinity of nickel was evidenced by precise diffraction measurements using synchrotron radiation. The spinel structure was not observed when copper was introduced. As a result, the alumina particles were more dispersed and covered the surface of the NiCu particles enriched with copper.