Prediction of Effectiveness Factor Using One-Dimensional Approximations for Complex Pellet Shapes and Abnormal Kinetics Expressions

NÉSTOR JAVIER MARIANI; MARÍA JOSÉ TAULAMET; SERGIO DARÍO KEEGAN; OSVALDO MIGUEL MARTÍNEZ; GUILLERMO FERNANDO BARRETO

INDUSTRIAL & ENGINEERING CHEMICAL RESEARCH

AMER CHEMICAL SOC

Lugar: Washington; Año: 2013 vol. 52 p. 15321 - 15329

0888-5885

This contribution undertakes the evaluation of one-dimensional (1D) models to approximate the behavior of actual three dimensional (3D) catalyst pellets, in the case of abnormal kinetics and close to the limit of steady state multiplicity. Two 1D models are tested: a one parameter model, called Generalized Cylinder (1D-GC) and a three parameter model termed Variable Diffusivity (1D-VD) model. A representative set of shapes presented by commercial catalytic pellets was selected to study the performance of the models to predict effective reaction rates. Kinetics expressions covering typical cases of thermal and self-inhibition effects have been considered. Predictions of effectiveness factor using 1D-GC and 1D-VD models are compared with numerical results obtained from Comsol Multiphysics environment for the 3D pellets. 1D-GC simpler approximation can lead to maximum errors exceeding 40%. On the contrary, the 1D-VD model allows reducing them to a level of 10%, even for the most challenging cases.