Yolk–Shell Pt-NiCe@SiO2 Single-Atom-Alloy Catalysts for Low-Temperature Dry Reforming of Methane

Abstract

Herein, we report a highly carbon resistant nanotubular yolk–shell Pt-NiCe@SiO2 single-atom-alloy (SAA) catalyst for low-temperature dry reforming of methane (DRM). A synergetic combination of the confined yolk–shell morphology and Pt–Ni SAA structures prevents carbon formation and provides excellent catalyst stability. The confined morphology of the yolk–shell structures can impede carbon deposition due to the facile CO desorption from the surface. Carbon formation can be further minimized by 0.25 wt % Pt promotion, showing an excellent stability for 120 h during DRM at 500 °C. The enhanced stability of the Pt0.25-NiCe@SiO2 catalyst can be attributed to the atomically dispersed Pt on the yolks forming Pt–Ni SAA structures encapsulated by a nanotubular SiO2 shell. The Pt–Ni SAA facilitates Pt–Ni interactions and enhances the reducibility of the Ni species, which further suppresses carbon formation during DRM. The developed bifunctional catalyst exhibits excellent resistance to coking by decreasing the effect of both main carbon formation reactions: i.e., CO disproportionation and CH4 decomposition. When the Pt loading is increased above 0.25 wt %, Pt nanoparticles form, leading to oligomerization of C–H species. Our results show that advantageous effects of both confined morphology and Pt–Ni SAA structures can lower the operating temperature of DRM without showing any catalyst deactivation.