Combustion of toluene–hexane binary mixtures in a reverse flow catalytic reactor

Abstract

This work is focused on the application of reverse flow reactors to the combustion of lean mixtures of aliphatic and aromatic hydrocarbons in air. For this purpose, hexane and toluene were chosen as model compounds. The combustion of binary mixtures of these compounds (up to 500 ppmV total hydrocarbon concentration) over a commercial Pt / Al 2 O 3 catalyst in reverse flow reactors has been studied both experimentally, in a bench-scale unit, and by simulations, using a heterogeneous mono-dimensional dynamic model, good correspondence being observed between both approaches. As general trend, it was observed that the behaviour of the reactor is determined mainly by the combustion enthalpies and reactivities of toluene and hexane. Hence, increasing total concentration and increasing fraction of toluene (the most reactive compound) lead to more stable operation. Regarding the kinetic inhibition effects, in the conditions studied no influence on the reactor performance was observed, probably because the hydrocarbons combust in different reactor zones. This behaviour can be extended to the combustion of aromatic and C 5 – C 8 alkanes, characterised by their relatively low concentrations (determined by their vapour pressure) and high reaction rates.