Effect of pore‐distributed coke on catalyst regeneration kinetics

Abstract

AbstractPrior experimental study by Haldeman and Botty has demonstrated that catalyst regeneration rates vary with conversion, showing a nearly constant rate of reaction in the early stages of regeneration and falling off rapidly at higher conversion levels. This peculiar reaction behavior calls for explanation in terms of pore structural changes. In this work a mathematical model is developed based on the interaction between catalyst pore structure and coke distribution in the pores. The model is able to associate overall regeneration kinetics with alternative pore‐distributed coke deposition patterns. Results exhibit a slight shallow rate maximum at an intermediate conversion level, in agreement with the prior experimental report. The model makes coke distribution in the pores accessible to experimental determination. The numerical results indicate that among pore structures with the same mean and overall pore volume, a larger variance offers a higher threshold for coke loading; for a given degree of dispersion, a smaller mean allows a higher coke loading.