Kinetic analysis of TiO₂-catalyzed heterogeneous photocatalytic oxidation of ethylene using computational fluid dynamics

Photocatalytic oxidation of ethylene was carried out over a TiO₂ catalyst at 295K using two types of non-ideal fixed-bed flow reactors: a rectangular reactor and a cylindrical reactor. Computational fluid dynamics (CFD) analysis using a low Reynolds number-type k-ε turbulence model was conducted to investigate the ethylene oxidation behavior in the reactors at various gas flow rates and ethylene concentrations in the inlet gas (ethylene concentration of 50-250ppm and gas flow rate of 50-250mL/min). In the rectangular reactor, steady-state activities were obtained for ethylene oxidation under all conditions. The rate of ethylene oxidation on the TiO₂ surface was analyzed in terms of Langmuir-Hinshelwood (L-H) type kinetics. The kinetic parameters for the surface reactions obtained via CFD analysis fit well with the experimental data. The CFD analysis also revealed that the ethylene concentration distribution in the reactor depended on the gas residence time distribution. We also carried out CFD analysis for the cylindrical reactor and compared the ethylene oxidation behavior with that in the rectangular reactor.