Chemical looping partial oxidation of methane (CLPOM) is a promising way to efficiently obtain syngas with a suitable H₂/CO ratio. The major challenge encountered in the CLPOM process is to design an oxygen carrier with excellent surface reactivity and bulk lattice oxygen mobility. In this paper, the surface and bulk properties of the La₂Ce₂O₇ oxygen carrier were modified by Ni, with the purpose of promoting methane activation and increasing the lattice oxygen availability. With the introduction of NiO, the methane conversion of the oxygen carrier was increased by about 3 times compared with the undoped one, while the H₂/CO ratio remained at about 2. The oxygen carriers were characterized by XRD, H₂-TPR, CH₄-TPR and CH₄-Pulse to investigate the influence of the doping on the structural characteristics of the oxygen carriers. The performance and characterization results show that the surface Ni species promote the activation of methane and its reaction with lattice oxygen, while the bulk Ni species weaken the strength of Ce-O. Moreover, the modified oxygen carrier shows no deactivation in terms of performance during 15 cycles and the phase transition is reversible, which demonstrates the excellent redox stability of the modified oxygen carrier. This work illustrates that the regulation of the surface catalytic sites and bulk lattice oxygen availability of the oxygen carriers through doping is an effective strategy to modulate the CLPOM performance of oxygen carriers.

chemical looping,partial oxidation,nickel,La2Ce2O7