Monolithic reactor for VOCs abatement: Influence of non-uniformity in the coating

Abstract

This article presents a theoretical study of the catalytic mineralisation of ethanol via acetaldehyde over manganese - copper mixed oxide catalyst deposited on a monolith reactor. The steady-state operation of the monolith reactor is represented by means a heterogeneous, one-dimensional, adiabatic model, which accounts for external (gas-solid) resistances to mass and heat transfer and internal resistances to mass transfer inside the catalytic coating (washcoat). The effect of catalyst accumulation at the corners of a square section channel is analysed. Under the operating conditions considered, the diffusional resistances have a significant effect on the effective rate of removal of Volatile Organic Compounds and cannot be neglected. Non-uniform coating causes a considerable deterioration of the averaged effectiveness factors of the two reactions under consideration and lower temperatures along the reactor are found. These lower temperatures, together with lower temperature drops over the external film cause additional negative impacts on the Volatile Organic Compounds conversion. The decrease in the reactor performance, caused by the catalyst accumulation, is magnified as the feed concentration rises. Consequently, higher feed temperatures and/or lower space velocities are necessary to ensure the complete destruction of the volatile organic compounds involved (ethanol and acetaldehyde).