THERMAL STABILITY OF PEROVSKITE-BASED MONOLITHIC REACTORS IN THE CATALYTIC COMBUSTION OF METHANE

Perovskite-based monolithic reactors have been studied for methane catalytic combustion. Monoliths have been prepared by washcoating cordierite honeycomb substrates with lanthanumstabilized g-Al2O3, on which LaMnO3 is dispersed. Scanning electron microscopy analysis showed a homogeneous distribution of LaMnO3 on the washcoat, which, after repeated aging cycles at 1100 °C, is still well anchored to cordierite. The catalytic activity in methane combustion is very promising, even higher than that measured on the corresponding catalyst powders with the same chemical composition. Isothermal catalytic activity measurements reveal that the first aging cycle slightly reduces the activity of fresh catalyst, while further repeated aging treatments do not deactivate the monolithic reactor. In autothermal conditions, the monolithic catalyst is able to ignite a mixture of CH4 (3% vol) and O2 (10%) at an inlet gas temperature of about 500°C, giving complete methane conversion and negligible CO and NOx emissions. Moreover, 50 h of operation under ignited conditions causes only minor deactivation of the catalyst