Effect of CO sub(2) on the Methane Combustion over a Perovskyte Catalyst at High Pressure

The effect of the CO sub(2) content (up to 30%) on the methane catalytic combustion over a perovskyte-based monolith has been investigated at high pressure (up to 8 bar). Catalytic tests have been performed by varying the preheating temperature and the operating pressure. The CO sub(2) adsorption over the catalytic surface has been evaluated through temperature-programmed desorption tests coupled to a kinetic model. Results show that the presence of CO sub(2) retards ignition, shifting the ignition pressure at higher values. However, once ignition has been attained, the catalytic surface temperature increases upon an increasing CO sub(2) content. These results have been explained by a double role of CO sub(2): on one hand, it affects the ignition through adsorption over the catalytic surface, and on the other hand, it decreases the gas thermal diffusivity, thus reducing the velocity of heat removal from the surface.