Regeneration of Catalytic Membrane Reactors

The commonly practiced method of regenerating coked catalysts or catalytic membranes is by combustion with air, air/stcam mixtures, air/nitrogen mixtures, or dilute oxygen streams with another carrier gas. 

However, the addition of an oxidant such as oxygen is not without some trade-off. To help solve the problem of catalyst deactivation due to carbon deposit in an alumina membrane reactor for dehydrogenation of butane, oxygen is introduced to the sweep gas, helium, on the permeate side at a concentration of 8% by volume. The catalyst service life increa.scs from one to four or five hours, but the selectivity to butene decreases from 60 to 40% at 480 C [Zaspalis et al., 1991b]. If oxygen is added to the feed stream entering the membrane reactor in order to inhibit coke formation, the butene selectivity decreases even more down to 5%. 

For those reactions such as dehydrogenation of butane or isobutanc which require frequent regeneration of the catalyst or catalytic membrane, a cyclic process involving reaction and coke-bumout steps in sequence may need to be considered. It is essential, however, that a purge step be installed between the reaction and the burnout steps to 

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