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.

Enhanced Thermocatalytic Stability by Coupling Nickel Step Sites with Nitrogen Heteroatoms for Dry Reforming of Methane

“…Recently, Kawi et al reported the highly stable and selective core/yolk–shell nanocatalysts, which behaved superior anti-coking/sintering performance. − Nickel nanoparticles confined in silica nanotubes showed high catalytic stability in ethanol steam reforming . Besides, Kim et al reported the confined yolk–shell morphology provided excellent catalytic stability for Pt–NiCe@SiO 2 catalysts …”

“…11 Besides, Kim et al reported the confined yolk−shell morphology provided excellent catalytic stability for Pt−NiCe@SiO 2 catalysts. 12 The addition of special metals or heteroatoms to cover stepedge sites of the nickel crystal surface has been proposed as an effective approach to inhibit the carbon nucleation 13 and improve the catalysts' anti-coking capacity. 14 The carbon nucleation on the step sites of nickel surface as the initial step in the carbon growth along the platform position shows low activation energy.…”

Recent Progress in Thermal Conversion of CO2 via Single‐Atom Site Catalysis

“…They reported Pt–Ni SAA and CeO 2 cores confined in nanotubular SiO 2 structure for DRM. [ 91 ] Ce species had strong interaction with both components in Ni–Pt SAA and may enter the lattice evidenced by the HRTEM and TPR. The oxygen vacancies improved the Ni dispersion.…”

Design Strategy, Synthesis, and Mechanism of Ni Catalysts for Methane Dry Reforming Reaction: Recent Advances and Future Perspectives

“…Kim et al reported Pt-NiCe@SiO 2 catalysts prepared by reverse microemulsion for MDR study . Pt–Ni single-atom-alloy was formed after the catalysts were hydrogen pretreated at 773 K. The H 2 -TPR profile showed the temperature reduction peak for NiCe@SiO 2 is higher than that for NiCe/SiO 2 WI , indicating that the yolk–shell NiCe@SiO 2 catalyst had the stronger metal–support interaction when compared to the impregnated catalyst.…”