Syngas chemical looping process: Ni–Fe bimetallic oxygen carriers for maximizing blue hydrogen yield

Abstract

The syngas chemical looping (SCL) process is an advanced thermochemical approach for hydrogen production with in situ carbon capture. This article proposes a novel Ni–Fe bimetallic oxide in a three-reactor chemical looping system. In the moving bed reducer, a mixture of NiO and Fe₃O₄ is countercurrently reduced by syngas to Ni and Fe/FeO. In the oxidizer, the Fe/FeO mixture is oxidized back to Fe₃O₄ by steam, producing high-purity H₂, while Ni remains unchanged. In the combustor, Ni is oxidized to NiO by air to supply heat, while Fe₃O₄ is maintained without further oxidation to Fe₂O₃. The reducer's operating conditions are optimized using the operating line diagram method and the multistage equilibrium model. Process simulation results show that the Ni–Fe oxygen carrier can increase blue hydrogen production efficiency by more than 5% compared to the Fe-based SCL process, while ensuring a carbon capture rate of over 99%.