Oxidative dehydrogenation of ethane in a fluidized bed membrane reactor

Abstract

The performance of a pilot scale fluidized bed membrane reactor (FLBMR) was studied experimentally in comparison to the conventional operation as a fluidized bed reactor (FLBR) for the catalytic oxidative dehydrogenation of ethane using a γ-alumina supported vanadium oxide catalyst. For both reactor configurations, the influence of process parameters such as temperature and contact time was investigated. Further, the experimental data obtained were compared to previous experiments with a fixed-bed reactor (FBR) and a packed-bed membrane reactor (PBMR) operated with a similar catalyst. For identical overall feed rates, the distributed oxidant feeding in the FLBMR improves the selectivity to ethylene significantly. The beneficial effect of oxidant dosing over the membrane is most pronounced at high temperatures and long contact times. Under limiting oxidant supply the FLBMR and the PBMR show a similar performance, but under moderate oxygen excess the FLBMR outperforms the PBMR significantly. The maximum ethylene yield observed in the FLBMR was 37% compared to 35% for the PBMR. Beside a high productivity, for the FLBMR a broader favorable operation range with respect to the oxygen–hydrocarbon ratio was observed, what indicates a lower sensitivity against oscillations and disturbances in the reactant feed, corresponding to a higher safety of operation. Because of an excellent heat transfer characteristics, the fluidized bed membrane reactor concept is very promising for maximizing the yield of the desired intermediates also in large-scale plants, especially for strongly exothermic reactions.