Thermal stability of perovskite-based monolithic reactors in the catalyticcombustion of methane

Perovskite-based monolithic reactors have been studied for methane catalyti c combustion. Monoliths have been prepared by washcoating cordierite honeyc omb substrates with lanthanum-stabilized gamma -Al2O3, on which LaMnO3 is d ispersed. Scanning electron microscopy analysis showed a homogeneous distri bution of LaMnO3 on the washcoat, which, after repeated aging cycles at 110 0 degreesC, is still well anchored to cordierite. The catalytic activity in methane combustion is very promising, even higher than that measured on th e corresponding catalyst powders with the same chemical composition. Isothe rmal catalytic activity measurements reveal that the first aging cycle slig htly reduces the activity of fresh catalyst, while further repeated aging t reatments do not deactivate the monolithic reactor. In autothermal. conditi ons, the monolithic catalyst is able to ignite a mixture of CH4 (3% vol) an d O-2 (10%) at an inlet gas temperature of about 500 degreesC, giving compl ete methane conversion and negligible CO and NOx emissions. Moreover, 50 h of operation under ignited conditions causes only minor deactivation of the catalyst.