Approximation of the Effectiveness Factor in Catalytic Pellets

SERGIO DARÍO KEEGAN; NÉSTOR JAVIER MARIANI; OSVALDO MIGUEL MARTÍNEZ; GERMÁN DÉLFOR MAZZA

CHEMICAL ENGINEERING JOURNAL

Elsevier Science Ltd

Lugar: Oxford, Inglaterra; Año: 2003 vol. 94 p. 107 - 112

1385-8947

The 1D model proposed by Burghardt and Kubaczka [1] to approximate the behavior of 3D catalytic pellets has been recently found able to provide accurate results for evaluating effective reaction rates when its parameter s is suitable adjusted [2]. This parameter represents the contraction of the cross section available for diffusion. A formulation coupling a first order Galerkin approximation with a truncated asymptotic expansion is proposed here to evaluate the effectiveness factor of single reactions in the range of interest ƒ{1/5<s<5 [2]. The formulation provides a 3% level of precision for essentially all normal kinetics of practical interest and a large range of abnormal kinetics. In particular, this conclusion includes reaction rates approaching a zero order reaction, for which large deviations arise from the use of previous approximations proposed in the literature. On the other hand, the extent of abnormal kinetics being accurately approximated is significantly enlarged.