Sorption enhanced chemical looping steam ethanol reforming for hydrogen production using calcium oxide/nickel oxide/iron oxide multifunctional catalyst

Abstract

This research studied the hydrogen production via sorption enhanced chemical looping reforming process from ethanol both computationally and experimentally. In the computer simulation work, four hydrogen production processes including conventional ethanol steam reforming (ESR), sorption enhanced steam reforming (SESR), chemical looping reforming (CLR) and sorption enhanced chemical looping reforming (SECLR) were performed using NiO as the oxygen carrier and CaO as the CO2 sorbent, and simulated on the basis of energy self-sufficiency, i.e. process energy requirement supplied by burning some of the produced hydrogen. The process performances in terms of hydrogen productivity, hydrogen purity, ethanol conversion, CO2 capture ability and thermal efficiency were compared at their maximized net hydrogen. In the experimental studies, Fe-based oxygen carrier was selected due to its high oxygen content. In order to combine with modified CaO sorbent, the limited integration from Fe and Ca interactions makes them less attractive and reliable. The investigation of different combination method (sol-gel, mechanical mixing and impregnation) and iron contents (5, 10 and 15 wt %) of Fe2O3/CaO-Al2O3 multifunctional catalysts were demonstrated and compared their activity and stability. Higher performance was found for multifunctional catalyst combined by impregnation method with 5 wt % Fe loading. Nevertheless, the H2 production was still inhibited and the deactivated catalyst was observed. Therefore, the catalyst was further developed to enhance its stability and regenerability for hydrogen production by utilization of hydrotalcite structure. Moreover, alloying Fe with Ni was also applied to improve the catalytic performance. This catalyst showed a stable behavior and maintained hydrogen selectivity over 10 repeated cycles.