Highly Active and Anticoke Ni/CeO2 with Ultralow Ni Loading in Chemical Looping Dry Reforming via the Strong Metal–Support Interaction

Oxygen carriers with active sites have attained wide attention for chemical looping reforming of CH4 recently thanks to their capacity to improve CH4 activation and oxygen reactivity. However, supported metals sintered significantly during multiple cycles, which entailed high metal loading (generally >5 wt %) to realize great performance promotion and caused coke formation. Herein, merely 0.1 wt % Ni addition into CeO2 could achieve remarkable enhancement of performance for chemical looping drying reforming of methane with CH4 conversion and CO selectivity of almost 100% as well as syngas productivity of 3.4 mmol/g without carbon deposition. This resulted from the encapsulation of Ni nanoparticles by CeO2 via the strong metal–support interaction during redox cycles preventing Ni nanoparticles from sintering, which brought about more surface oxygen vacancy for CH4 activation compared with CeO2. Nonetheless, the covering could not be observed in 5Ni/CeO2 resulting in the evident growth of Ni nanoparticles, which induced CH4 cracking on them and thus coke formation.