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Sorption-enhanced chemical looping reforming of ethanol for hydrogen production was investigated using Fe2O3as oxygen carrier and modified CaO-based Al2O3as CO2sorbent. Combined Fe2O3/CaO-Al2O3multifunctional 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 H2purity of 70% in the pre-breakthrough period which lasted for 60 min at 600 °C. This was attributed to the preserving of Ca12Al14O33inert support in the structure during the preparation as shown by XRD results, leading to higher surface area as determined by N2physisorption and to prevention of particle agglomeration as evidenced by SEM-EDX. Although the H2production was inhibited by the presence of Ca2Fe2O5phase, 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.

Ethanol, especially that produced from biomass, is considered as a renewable and carbon-neutral candidate to produce hydrogen. Performances of NiFe–MgAl bifunctional catalysts, in terms of activity, stability, and regenerability, in chemical looping reforming (CLR) of ethanol were studied. The NiFe–MgAl bifunctional catalysts were prepared from hydrotalcite-like compounds by the co-precipitation method. Various characterization techniques, that is, X-ray diffraction, inductively coupled plasma, nitrogen adsorption/desorption, H2-temperature-programmed reduction, and transmission electron microscopy, were used to determine properties of fresh and spent catalysts. In addition, O2temperature-programmed oxidation, scanning electron microscopy, and Raman analyses were used for observation of coke formation on the spent catalysts. Meanwhile, in situdiffuse reflectance infrared Fourier transform spectroscopy can verify the evolution of the catalyst during the reactions. It was observed that the NiFe–MgAl catalyst showed higher catalytic activity and stability than the monometallic Fe–MgAl and Ni–MgAl catalysts. More specifically, the NiFe–MgAl catalyst provided the highest H2concentration up to 80% at a low reaction temperature of 500 °C. This high performance was ascribed to the formation of Ni–Fe alloy particles. The combination of pulse experiments and X-ray photoelectron spectroscopy analysis elucidated that the iron particle at the surface was in the form of FeO that can oxidize the carbon deposits, resulting in the suppression of coke formation. In addition, the NiFe–MgAl catalyst can maintain high hydrogen selectivity for 10 repeated cycles.