Influence of oscillating external pressure on gas-phase reactions in porous catalysts

Abstract

It is shown that the effectiveness factor of an isothermal, first order, gas-phase catalytic reaction may be increased by operation under conditions of oscillating total pressure. The mathematical analysis considers two models. An Eulerian model, based on the bulk diffusion control and high permeability limit of the dusty gas model, is used to study the simple isomerization reaction. To extend the results to polymerization and cracking reactions which experience volume change, a Lagrangian model which neglects diffusion is developed. Solutions from both models agree in the limit of large Thiele modulus. It is in this limit that the pressure oscillation technique shows greatest promise for improving catalyst performance. Perhaps the most important conclusion of the present analysis is that pressure oscillations also show promise as a means to control the selectivity of complex reactions.