Pulsed thermo-kinetic (PTK) measurements : methanation of carbon dioxide

An investigation was conducted to develop a modified Pulsed Thermo Kinetics (PTK) apparatus utilizing a fluidized bed as the heating unit. A differential thermal detector was constructed with standard Swaglok fittings that withstand severe experimental conditions and provide a short response time. This fluid bed PTK detector was used in the study of carbon dioxide methanation on three nickel catalysts with well characterized crystallite size distributions. Based on the experimental results, it was concluded that the hydrogenation of carbon dioxide is initiated by the dissociative adsorption of CO2 on a few highly active sites. At 265 [degrees] C, the hydrogenation of a partially hydrogenated CO complex is rate limiting. Above 260 [degrees] C, the specific activity increases with nickel crystallite size.