Determination of styrene hydrogenation surface kinetics through detailed simulation of the hydrogen uptake curve

Abstract

The styrene hydrogenation over Pd/C in a three-phase dead-end stirred tank reactor has been simulated. The mass transfer coefficients were calculated based on experimental data. The fast intrinsic reaction kinetics did not allow the effects of the gas-liquid and liquid-solid mass transfer to be ignored. A rigorous model is described which includes all mass transfer steps with a Langmuir-Hinshelwood model of the surface chemical reaction. The adsorption constants of hydrogen, styrene and ethylbenzene on catalyst active sites were estimated from a single experimental reaction profile. The parameterised model was validated against 6 further sets of experimental data which were not included in the parameters' estimation procedure. Results indicate the ethylbenzene, styrene and hydrogen adsorption to have an equilibrium constant of 148.34 L mol-1, 847.72 L mol-1 and 19984 L mol-1, respectively. The intrinsic rate constant for the 4.63% Pd/C catalyst is 0.0542 mol gcat-1 s or 1.17 mol gPd-1 s-1. This work demonstrates that the analysis of the whole hydrogenation reaction profile in combination with detailed mass transfer resistance evaluation can provide fundamental system properties.