Platinum catalysed aqueous alcohol oxidation: model-based investigation of reaction conditions and catalyst design

A dynamic transport model is derived to describe the platinum catalyzed aq. alc. oxidn., considering a single spherical catalyst particle surrounded by a stagnant liq. film. The transport model is based on a heterogeneous kinetic model with mass transfer and intra particle diffusion resistances. The developed model uses the kinetic model of Markusse et al. (Catal. Today 66 (2001) 191) and is validated with the exptl. kinetic data of Me a-D-glucopyranoside (MGP) oxidn. obtained by Vleeming et al. (Ind. Eng. Chem. Res.). The model is used to investigate the effect of process conditions, catalyst and particle properties, and transport parameters on the performance of the catalyst for alc. oxidn. It is found that the electron cond. of the catalyst support affects the rate of MGP oxidn. esp. at low bulk liq. oxygen concns., while at high bulk liq. oxygen concns., the catalyst support cond. does not play a role. A major cause of catalyst deactivation is over-oxidn. under oxygen rich conditions. This can be reversed by applying redox-cycle operation, an alternating exposure of the catalyst to oxidative and reductive environments. The advantages of redox-cycle application are demonstrated using the developed model. For reactions of neg. order, such as MGP oxidn., at high bulk oxygen concns. (CO2,L>0.3 mol/m3), concg. the active catalytic material in a layer buried some distance from the surface (core) gives considerable better performance than the conventional \"egg shell\" design of shallow deposition near the surface or uniform distribution. However, at low bulk oxygen concns. (CO2,L?0.3 mol/m3), the performance of the uniform or egg shell distribution catalyst is superior to the core catalyst. [on SciFinder (R)]