Layered Double Hydroxide-Derived Intermetallic Ni3GaC0.25 Catalysts for Dry Reforming of Methane

Abstract

A NiMgGa-layered double hydroxide (NMG-LDH) is synthesized as an efficient catalyst precursor for dry reforming of methane (DRM). NMG-LDH is converted to an intermetallic Ni3Ga/MgO catalyst upon reduction. Compared to a monometallic Ni/MgO catalyst prepared from NiMg-LDH, the Ni3Ga/MgO catalyst exhibits high CH4 (similar to 48%) and CO2 (similar to 52%) conversions as well as excellent stability against coking during DRM. The reversible phase transition between intermetallic Ni3Ga and Ni3GaCx is demonstrated by in situ characterizations with the interstitial carbon being involved in the catalytic cycle of DRM to produce CO and H-2. According to density functional theory calculations and the experimental study, the LDH-derived Ni3Ga intermetallic catalyst is converted to the Ni3GaC0.25 phase when carbon atoms dissociated from CH4 penetrate into the octahedral interstices of the Ni3Ga lattice during DRM at 600 degrees C. The formed Ni3GaC0.25 is proven effective in converting the interstitial carbon rapidly into CO to suppress its conversion to the coke, thus improving the stability of the catalyst.