Chemical looping hydrogen generation with multi-layer core-shell oxygen carrier of Fe@Al-Ti

Fe-Al-Ti oxygen carriers have good cycling stability and good properties of anti-carbon deposition in the chemical looping hydrogen generation (CLHG) process. However, the formation of FeAl₂O₄ reduces hydrogen yield and increases sintering. To weaken the formation of FeAl₂O₄ and to promote properties, the core-shell oxygen carriers of Fe@Al-Ti were prepared by self-assembly template combustion method, which took TiO₂ as the inter-layer to separate Fe₂O₃ and Al₂O₃. The effect of multi-layer core-shell structure on reaction performance was evaluated on a fixed bed. The results indicated that the inter-layer of Fe@Al-Ti oxygen carriers effectively weakened the contact between Fe₂O₃ and Al₂O₃, thus reducing the formation of FeAl₂O₄ and improving properties of anti-sintering. The Fe@Al-Ti oxygen carriers significantly prevented carbon deposition and surface agglomeration, and had great cycling stability during the CLHG cycles. The core-shell oxygen carrier with a molar ratio of Al∶Ti=3.5∶1 got the highest carbon conversion rate and H₂ yield, and oxygen storage capacity in a single cycle, with 57.4%, 75.0%, and 6.01 mmol/g, respectively, which were 28.4%, 30.0%, and 26.9% higher than those of non core-shell Fe-Al-Ti oxygen carriers.