Hydrogen by steam reforming of ethanol over Co–Mg incorporated novel mesoporous alumina catalysts in tubular and microwave reactors

Abstract

Bio-ethanol is an excellent hydrogen carrier with a good potential to be used as a resource for on-board hydrogen production. In this work, a set of new Co incorporated mesoporous alumina (MA) catalysts, which were modified with Mg, were synthesized and tested in steam reforming of ethanol. Results proved that, the synthesis route of these materials had a highly significant effect on their catalytic performances. Co@Mg–MA and Co–Mg–MA catalysts, which were prepared by direct addition of Mg into the mesoporous alumina framework, gave the best performance in steam reforming of ethanol, with very high hydrogen yield values. This was concluded to be due to the presence of Co0 and CoO phases within the structures of these catalysts. However, Co–Mg@MA and Co@MA catalysts, which were prepared by the impregnation of Co/Mg or Co into mesoporous alumina, mainly catalyzed ethanol dehydration reaction to yield ethylene, rather than steam reforming. This was concluded to be due to the high Lewis acidity of these catalysts and the presence of cobalt aluminate phase in their structure. Activity tests of the synthesized catalysts were made both in a tubular reactor which was conductively heated and also in a focused-microwave system. Better energy utilization and more stable performance with much less coke formation were achieved in the focused-microwave reactor than the conventionally heated system.