Coke resistant NiCo/CeO2 catalysts for dry reforming of methane derived from core@shell Ni@Co nanoparticles.

Core@shell Ni@Co and bimetallic alloyed Ni–Co nanoparticles with controlled Co/Ni compositions were prepared and supported on CeO 2 to investigate their performance in catalytic dry reforming of methane (DRM) and occurrence of sintering and coking. Increasing the Co/Ni ratio significantly reduced coke deposition while maintaining catalytic activity for DRM. However, a Co/Ni ratio > 1 caused a rapid decrease in activity. The Ni@Co 1 /CeO 2 catalyst exhibited the highest CH 4 and CO 2 conversions, with long-term stability during DRM at 800 °C for 100 h. The initial core@shell structure of the Ni@Co 1 /CeO 2 catalyst transformed to a homogeneous alloy after DRM at 800 °C for 10 h, losing its Co shell. However, the bimetallic alloyed Ni–Co 1 /CeO 2 catalyst transformed into a non-uniform alloy rich in Co on the surface after DRM for 10 h. As the elemental distribution of the NPs becomes more homogeneous, Ni–Co 1 /CeO 2 exhibit similar catalytic activity to Ni@Co 1 /CeO 2 after 50 h. The oxygen vacancies on the CeO 2 surface provided oxygen atoms to the Ni surface, removing carbon species deposited and releasing CO. Therefore, Ni@Co 1 /CeO 2 catalyst provides excellent catalytic activity and stability due to the rapid formation of a homogenous alloy and the synergistic effect of Co and CeO 2. [Display omitted] • Core@shell Ni@Co nanoparticles with controlled Co/Nicompositions were prepared. • Ni@Co x /CeO 2 catalysts show high activity and stability in DRM. • The increased Co content of Ni@Co x /CeO 2 improves the coke resistance. • Ni@Co 1 /CeO 2 catalysts were transformed into a homogeneous NiCo alloy during DRM. [ABSTRACT FROM AUTHOR]