Occurrence of Multiple Steady States in the Catalytic Combustion of Propane

Abstract

Abstract This paper reports experimental results on the existence of multiple steady states in a catalytic combustor for various inlet temperatures (Tin), velocities (Vin), and equivalence ratios (φin). The catalyst was comprised of binary transition metal oxides (CO3O4, Cr2O3) supported on alumina wash-coated ceramic honeycomb substrates. Only oxidation of lean propane-air mixtures (equivalence ratios ⩽0.2) were studied. Multiple steady states were detected only over a narrow range of inlet temperatures (600-670°K). For temperatures outside this range only one steady state exists, while for temperatures in this range at least two steady states, corresponding to heating up and cooling down, exist. In a few cases, when these two steady states were widely separated, one and sometimes two additional steady states (intermediate steady states) were detected. These intermediate steady states, in general, lie close to the heating up or cooling down steady states. For a fixed set of inlet conditions, different st...