(621cd) Acetophenone Hydrogenation on Rh/Al2O3 Catalyst: Intrinsic Reaction Kinetics and Effects of Internal Diffusion

Acetophenone hydrogenation on Rh/Al₂O₃ catalyst: Intrinsic reaction kinetics and effects of internal diffusion

Shinbeom Lee, Zhiyang Yu, Arvind Varma

School of Chemical Engineering, Purdue University, 480 Stadium Mall Drive,

West Lafayette, IN 47907, USA

ABSTRACT

Acetophenone hydrogenation on 1% Rh/Al₂O₃ catalyst was conducted using several support sizes to study intrinsic kinetics and internal diffusion effects. In the first part of this work, results on different noble metals and supports were compared, and 1% Rh/Al₂O₃ was selected. The intrinsic reaction kinetic modeling with Langmuir-Hinshelwood mechanism was conducted based on experiments at 60-100 ^oC, 1.1-4.1 MPa P_H2 and 0.04-0.4 M C_AP.owith powder catalysts. The most appropriate kinetic model was composed of dissociative and non-competitive hydrogen adsorption with saturated active sites for organics, as confirmed by reasonable agreement with the literature. The kinetic parameters including activation energies, adsorption heat of hydrogen, and adsorption constants were also compared with the literature. With the obtained reaction kinetic model, the internal diffusion effects were investigated with different sized catalysts and diffusion-reaction models. Catalyst distributions and active sites numbers for larger size supports (0.5 and 2.5 mm diameters) were characterized and applied to the models with modifications for egg-shell distributions and active site differences. The models developed in this work provided good estimates, explaining the effect of internal diffusion inside catalyst particles on reaction rates and selectivities, and are therefore suitable for use in future reactor studies.  

Keywords: acetophenone hydrogenation, Rh/Al₂O₃, intrinsic reaction kinetics, effectiveness factor, slurry reactor