Development of Fe2O3-based, Al2O3-stabilized Oxygen Carriers using Sol-gel Technique for H2 Production via Chemical Looping

A modification of the chemical looping combustion (CLC) process allows the production of high purity hydrogen from biomass (with simultaneous CO2 capture) on the distributed scale. Here, we report the development of Fe2O3-based, Al2O3-supported oxygen carriers using a sol-gel technique. We assess the influence of the iron precursor on the morphological properties, chemical composition and cyclic redox stability of the oxygen carrier. Three iron precursors, i.e. iron nitrate, iron chloride and iron acetylacetonate, were used to synthesize oxygen carriers containing 80 wt. % of Fe2O3. Using iron nitrate and iron acetylacetonate as the iron precursor resulted in materials with a high H2 yield. However, both materials showed some decay in the hydrogen yield with cycle number. Al2O3-stabilized Fe2O3 synthesized using iron chloride as the iron precursor showed no appreciable decay over the 15 cycles tested, albeit the amount of hydrogen produced was significantly lower when compared to the other two iron precursors. This observation can be attributed to the large fraction of hercynite (FeAl2O4) in this material. Hercynite stabilizes iron and prevents sintering, but does not participate in the redox reactions.