Effect of the catalyst properties on the performance of a reverse flow reactor for methane combustion in lean mixtures

Abstract

This paper analyses the role of the catalyst properties (specially the different activities and thermal stabilities of the studied catalysts) on the performance of reverse flow reactors (RFR) for the combustion of lean methane-air mixtures. Two different γ-Al2O3-supported industrial catalysts have been selected as representatives of the two types of catalysts used in these processes: metal oxides (mainly Mn oxide) and noble metals based (Pd) catalysts. The different activities and stabilities of these catalysts (Pd is more active but undergoes thermal deactivation) largely affect the operation of the RFR. The implications of these differences are comprehensively studied using both numerical simulation (considering an heterogeneous one-dimensional model), and a bench scale RFR featuring a novel temperature control system that allows an instantaneous compensation of heat losses, obtaining a performance similar to that expected for larger industrial scale units. Therefore, it is concluded that the catalyst selection, which depends mainly on the nature of the emissions to be treated, largely affects the main operation variables to be fixed in order to obtain a stable and autothermal operation in a RFR, i.e. preheating temperature, inlet concentration and switching time.