Performance of a Cu–Fe‐based oxygen carrier combined with a Ni‐based oxygen carrier in a chemical‐looping combustion process based on fixed‐bed reactors

The application of chemical‐looping combustion (CLC) based on fixed‐bed reactors for distributed medium‐ and small‐scale hot‐water and steam gas‐fuelled boilers is promising due to its low NO x emission, high energy efficiency and nearly zero energy consumption in carbon capture. For fixed‐bed reactors, a wide operating temperature window ( T w ) for the oxygen carrier (OC) is crucial to ensure the performance and cycle life of the OC. The performance of Cu30–Fe50/Al20‐M combined with different Ni‐based OCs was investigated to extend the T w ( L ) of 600°C for Cu30–Fe50/Al20‐M to a lower temperature, which was developed previously. The different Ni‐based OCs would work as CH 4 steam reforming catalysts if their required reduction temperatures were significantly lower than the T w ( L ) of Cu30–Fe50/Al20‐M. Results showed that a Ni‐based OC of Ni60/Al40‐M could be reduced with CH 4 /H 2 O with an S/C of 1.0 at a temperature of 450°C. The combination of Cu30–Fe50/Al20 and Ni25/Al75‐I, which was packed in the bed by a mixing method, exhibited a low‐temperature reactivity and T w ( L ) was lowered from 600°C to 490°C. Moreover, carbon deposition and an intermediate compound, NiFe 2 O 4 , which was found in a composite OC of Ni–Cu–Fe–/Al, were not detected during the reduction step. Based on the results, a new CLC process, which was characterised by an integrated methane steam reforming in the reduction step, was proposed. © 2018 Society of Chemical Industry and John Wiley & Sons, Ltd.