Study on the metal-support interaction in the Ru/C catalysts under reductive conditions

A metal-support interaction in the carbon-supported ruthenium samples in a hydrogen medium was studied. The carbonaceous graphite-like composite material Sibunit with a specific surface area (SSA) of 320 m2/g was used as a support. The support was additionally treated at 1900 °C in an inert medium to provide the graphitization of the amorphous carbon. This procedure drops the SSA value dramatically. Both the initial and graphitized supports were also kept in a nitric acid to increase the amount of the oxygen-containing surface groups. Ruthenium was deposited from a ruthenium (II) ammonia complex. The strongest metal-support interaction resulting in an intensive hydrogenation of the carbon support was observed in the case of oxidized support. Two explanations of the phenomenon were proposed. First of all, methanation of the oxygen-containing surface groups contacting with the metal particle occurs at lower temperature and with higher rate if compared with other carbon species. Secondly, these groups provide higher hydrophilicity of the support and facilitate the formation of the well dispersed and finely distributed ruthenium particles. The graphitization procedure was found to stabilize the samples towards the hydrogenation process.