Kinetics of o-Xylene Combustion over a Pt/Alumina Catalyst

o-Xylene combustion in air over a Pt/γ-Al₂O₃ catalyst was investigated in a laboratory reactor at low concentrations typical for depollution applications. The results evidenced a slightly negative influence of o-xylene concentration on combustion rate. A kinetic model of the combustion process was developed by using the Langmuir-Hinshelwood mechanism, assuming the surface reaction between adsorbed oxygen atoms and adsorbed o-xylene molecules as controlling step. The rate expression includes the influences of o-xylene and water adsorption on the active centers of the catalyst. The estimation of rate expression parameters is based on o-xylene conversion measurements obtained under conditions free of influences of physical steps. The o-xylene combustion in air over a Pt/γ-Al₂O₃ catalyst was studied under conditions typical for depollution applications. A kinetic model based on the Langmuir-Hinshelwood mechanism is formulated, accounting for the experimentally observed negative influences of o-xylene and water concentrations on process kinetics. The reliability of the proposed model is demonstrated by comparing its predictions with measurements.