Processing and characterization of Fe-based oxygen carriers for chemical looping for hydrogen production

Abstract Until now various oxygen carrier particles have been proposed for use in chemical looping processes. Their chemical performance is determined not only by their composition and their microstructure/morphology but also by the reaction condition of the processes in which they are utilized. In the present work, iron based oxygen carriers supported on Al 2 O 3 and MgAl 2 O 4 were spray dried and heat treated to have a suitable morphology and sufficient mechanical properties for chemical looping. The MgAl 2 O 4 -support was in situ generated from MgO and Al 2 O 3 by reaction sintering. After physical characterization and determining their compressive strength the oxygen carriers were tested in the chemical looping reforming process for producing syngas in a lab-scale batch fluidized-bed reactor. The suitability of utilizing steam regeneration was investigated for both oxygen carriers by relating their chemical performance to their composition. It was shown that the Al 2 O 3 -supported oxygen carrier deactivated after 9 cycles of steam regeneration because of the accumulation of an in-situ formed FeAl 2 O 4 -phase due to an irreversible reaction between support and the active phase. This deactivation was successfully avoided by replacing the Al 2 O 3 -support with MgAl 2 O 4 . This Fe 2 O 3 /MgAl 2 O 4 oxygen carrier could be subsequently regenerated by steam, making it suitable for chemical looping for hydrogen generation.