Influence of the support on the state of nickel in the Ni/SiO2, Ni/ZrO2, and Ni/SO4/ZrO2 oxide systems studied by diffuse-reflectance IR spectroscopy

The Ni/SiO2, Ni/ZrO2, and Ni/SO4/ZrO2 systems were studied by diffuse-reflectance IR spectroscopy using CO as a probe molecule. The Ni/SiO2 and Ni/ZrO2 systems are similar in properties, and the state of nickel in the Ni/ZrO2 system is determined by the specific surface area. In the Ni/SO4/ZrO2 system, the surface sulfur compounds affect substantially the state of nickel: Niδ+ species with a partial positive charge are formed due to the strong electron-acceptor properties of the sulfur compounds.