Transient operation of a perovskite partially coated monolith at high pressure

This work deals with the experimental study of transient ignition during high-pressure combustion of CH4-enriched syngas. The structured catalyst is a monolith where only the external channels are coated with 20 wt. % LaMnO3/La-γAl2O3 (catalyst coating degree of 80 %). This novel core-shell configuration has shown the opportunity to get complete methane conversion thanks to the occurrence of homogeneous reactions also in the uncoated central channels. Here, homogeneous combustion is stabilized by catalytic combustion occurring in the external channels. In this work, experimental tests were carried out under high pressure conditions (up to 9 bar). It has been found that the time required to get ignition increases as the coating degree decreases. The longer time is related to the time required by homogeneous reaction to be activated and stabilized in the uncoated channels. High CO2 content in the feed mixture retards ignition due to CO2 adsorption over the catalyst surface at temperature lower than 600 °C which negatively affects the catalytic reaction.