| A series of silica supported Ni, Co, Fe, and Ru catalysts were prepared and tested for CO(,2) methanation activity. Low pressure tests were conducted from 475 to 725 K. Limited high pressure tests were conducted at low temperatures. A detailed kinetics study was conducted on Ni/SiO(,2) at low pressure over a wide range of H(,2) and CO(,2) concentrations. The data were fit to a series of Langmuir-Hinshelwood rate equations. All of the catalysts were characterized using temperature programmed desorption to determine heats of H(,2) adsorption.;The Co catalyst has the highest intrinsic rate of CO(,2) hydrogenation followed by Ru and Ni. A mechanism involving dissociative adsorption of CO(,2) followed by dissociation of CO to an active carbon intermediate is consistent with the data and provides the most meaningful interpretation. Heats of hydrogen adsorption range from 88 kJ/Mole for Ni/SiO(,2) to 145 kJ/mole for Co/SiO(,2). The activity data do not correlate well with the heats of hydrogen adsorption. |
