Fe2O3/CaO-Al2O3 multifunctional catalyst for hydrogen production by sorption-enhanced chemical looping reforming of ethanol

Sorption-enhanced chemical looping reforming of ethanol for hydrogen production was investigated using Fe2O3 as oxygen carrier and modified CaO-based Al2O3 as CO2 sorbent. Combined Fe2O3/CaO-Al2O3 multifunctional catalysts were demonstrated and prepared by different methods including sol-gel, mechanical mixing, and impregnation at different Fe contents (5, 10, and 15 wt%). The results showed that the multifunctional catalyst prepared by impregnation method with 5 wt% Fe loading provided the highest H2 purity of 70% in the pre-breakthrough period which lasted for 60 min at 600 °C. This was attributed to the preserving of Ca12Al14O33 inert support in the structure during the preparation as shown by XRD results, leading to higher surface area as determined by N2 physisorption and to prevention of particle agglomeration as evidenced by SEM-EDX. Although the H2 production was inhibited by the presence of Ca2Fe2O5 phase, a stable performance was found for at least 5 repeated cycles both for sorption capacity and oxygen carrier. The ease of decarbonation was also observed with this material as confirmed by DSC-TGA analysis. This highlighted the mutual advantages of Fe in CaO sorption stability and Ca in Fe oxygen carrier stability which could offset their intrinsic weak robustness.