Combustion of CH 4 over a PdO/ZrO 2 catalyst: an example of kinetic study under severe conditions

Abstract

A kinetic study on CH 4 combustion over a very active PdO/ZrO 2 catalyst with high Pd loading (10% w/w of Pd) is presented as an example of a demanding problem which requires both the development of appropriate experimental tools and a theoretical insight on surface chemistry. The use of an annular catalytic reactor as a tool to collect kinetic data under unusually severe conditions (high temperature and CH 4 concentration) is described in comparison with the use of a conventional packed bed reactor. In particular, problems related to the biasing effects of mass, heat and momentum transfer are addressed. Kinetic data addressing the effects of CH 4, O 2, H 2O and CO 2 concentration in a temperature range from 400 to 550 °C are analysed by means of a purely empirical power law model and of a formal kinetic model based on literature indication assuming methane dissociative adsorption as the rate controlling step.