Selectivity control of NiO-based oxygen carriers for chemical looping methane anaerobic oxidation to syngas

Ni-based oxides as oxygen carriers usually show high activity for chemical looping methane anaerobic oxidation, but the selectivity control for partial oxidation of methane to syngas is challenging. Here, we report a modulated NiO-based oxygen carriers that can selectively oxidize methane to CO and H 2 with high conversion under relatively low temperatures (700 °C) via a strategy of hydrotalcite derivatives (MMO). Selective syngas production (96.0 %) was obtained over the Ni 1.5 Mg 1.5 Al-MMO with excellent methane conversion of 93.9 % at 700 °C. The modulation of Mg content in Ni 3−x Mg x Al-MMO can alter the reducibility of oxygen species, thereby enabling targeted control of product selectivity. The introduction of Mg reconfigures the local coordination environment of Ni, promoting the formation of Ni-O-Mg. This structural modification enhances selectivity by regulating reducibility, while simultaneously improving catalytic stability by effectively suppressing Ni sintering and phase separation from Al 2 O 3 . Notably, the derivative effects of the hydrotalcite precursor during preparation promote the uniform formation and dispersion of Ni-O-Mg. This study investigates the impact of reactive oxygen species in nickel-based oxygen carriers on the product selectivity for chemical looping methane anaerobic oxidation.