OP-II-3

PP-I-8Experiments carried out under kinetic control revealed that hydrogen peroxidewas successfully formed on the catalyst surface, but it was decomposed as thereaction time was prolonged. The mass balances of the components wereconsidered in detail. A Langmuir-Hinshelwood rate mechanism was proposed basedon the competitive adsorption of hydrogen and oxygen on the palladium surface. Theadsorption and desorption steps are assumed to be rapid enough to reach quasiequilibria,while the surface reaction steps are assumed to limit the rates. Thesurface reactions leading to the formation of hydrogen peroxide and water wereassumed to be rate determining, after which the rate equations describing the systemwere derived and the kinetic parameters were estimated by nonlinear regressionanalysis. The model gave a good fit to the experimental data and it was used topredict the system behaviour under batch conditions (See Fig. 1).Fig. 1. Production of hydrogen peroxide and water (o) and fitting (-) at-5°C and 15 bar, partialpressure of H 2 1 bar and O 2 6 bar.References[1]. Voloshin, Y.; Halder, R.; Lawal, A. Kinetics of hydrogen peroxide synthesis by direct combinationof H 2 and O 2 in a microreactor. Catalysis Today 2007, 125, 40.[2]. Melada, S.; Rioda, R.; Menegazzo, F.; Pinna, F.; Strukul, G. Direct synthesis of hydrogenperoxide on zirconia-supported catalysts under mild conditions. Journal of Catalysis 2006, 239,422.[3]. Inoue, T.: Schmidt, M. A.; Jensen, K. F. Microfabricated multiphase reactors for the directsynthesis of hydrogen peroxide from hydrogen and oxygen. Industrial and Engineering ChemistryResearch 2007, 46, 1153.AcknowledgementsPierdomenico Biasi gratefully acknowledges the PCC (process chemistry centre), AboAkademi, Finland and the Johan Gadolinian scholarship for financial support.234