(600bn) Novel Ferrite Materials for Efficient H2 Production and CO2 Separation Using Chemical Looping Hydrogen Production

The chemical looping hydrogen (CLH) production process is an alternative method to water-gas shift to generate pure H₂, as well as a separate stream of pure and easily-sequestered CO₂, from any synthesis gas without complicated and expensive separations equipment.  Synthesis gas is used to reduce a metal oxide material at moderate to high temperatures as it leaves a gasifier (500°C to 800°C), producing a stream of CO₂ and H₂O.  The resulting reduced metal is then oxidized with H₂O to produce H₂ and regenerate the metal oxide.  This process requires use of a metal oxide material that achieves high H₂ and CO conversions to H₂O and CO₂ during the reduction step.  Complete regeneration of the metal oxide using only H₂O as an oxidant is also desirable.   In this study, the mixed metal ferrites CoFe₂O₄ and NiFe₂O₄ have been investigated as metal oxide candidates for the CLH process.  The ability of these ferrites to oxidize H₂ and CO in the syngas to H₂O and CO₂ during the reduction step was compared to that of the Fe₂O₃ in a packed bed reactor and found to be nearly equivalent. Unlike Fe₂O₃, the mixed metal ferrites were regenerated with H₂O oxidation only, allowing all the H₂ and CO used during the reduction step to be recovered as H₂ during oxidation.  Experimental results also show the H₂ production capacity of the reduced ferrites to be much greater than that of the Fe₂O₃ per cycle under the same conditions.  Long-term cyclability tests showed the CoFe₂O₄ material to cycle with great consistency.