Modeling the effect of particle-to-bubble adhesion on mass transport and reaction rate in a stirred slurry reactor : influence of catalyst support

The adhesion of catalyst particles to the gas–liquid interface significantly influences the rate of reaction in a three-phase gas-inducing stirred slurry reactor. For the Pd-catalyzed glucose oxidation reaction at mass transport-limited conditions, the experimental reaction rate is higher for lyophobic 3% Pd/C catalyst than for lyophilic 3% Pd/SiO2 catalyst. This is attributed to a higher particle-to-bubble adhesion (PBA) of the Pd/C catalyst. The interfacial catalyst concentration is quantified by a PBA equilibrium parameter in a PBA isotherm. The classical resistances-in-series "GLS model" cannot describe the overall reaction rate. An additional gas-to-solid "GS model" is presented with a gas-to-solid mass transfer coefficient to describe the increased rate of reaction by the catalyst particles adhered to the gas–liquid interface. The PBA equilibrium parameter and the gas-to-solid mass transfer coefficient during reaction are estimated as a function of mixing intensity, oxygen partial pressure, and catalyst concentration. The combined GLS–GS model adequately describes the experimentally observed reaction rates.