(691h) Highly Carbon-Resistant Silica Nanotube Supported Pt-Ni-Ce Catalysts for Low Temperature Dry Reforming of Methane

Dry reforming of methane (DRM) is a promising process to utilize CO₂ from natural gas combustion and biogas to produce synthesis gas. To date, Ni-based catalysts have been widely studied for DRM due to their high activity and low cost. However, Ni-based catalysts can undergo fast deactivation by carbon formation and metal sintering, and DRM is a highly endothermic reaction, which requires high operating cost and energy. Therefore, developing a catalyst presenting high DRM activity and stability at relatively low reaction temperatures is of interest. Several studies have shown that promoting small amount of Pt to Ni-based catalysts can increase the DRM performance.

In this work, we have prepared silica nanotube supported Pt-Ni-Ce catalysts for low temperature (500 ºC) DRM. The active Pt-Ni-Ce yolks are surrounded by a silica nanotube shell constructing multi–yolk–shell nanotube structure. Our results show that carbon formation is detected on the catalyst without Pt promotion after DRM reaction, while the deposited carbon amount decreases when Pt is promoted at 0.1 wt.%. Interestingly, no distinct carbon is observed for 0.25 wt.% Pt promoted catalyst, yet carbon starts to form again at Pt promotions above 0.25 wt.%. The synthesized multi–yolk–shell nanotube structured catalyst shows much longer stability than a conventional wet impregnated catalyst due to the confinement effect, and 0.25 wt.% Pt-promoted catalyst presents the highest resistance to carbon deposition than any other Pt loadings under DRM. Positive effect of Pt promotion is pronounced in the H₂-TPR analysis indicating that Pt increases the reducibility of Ni species. The Pt peak in the XRD shifts to a higher angle after H₂ reduction and DRM reaction, suggesting Pt species can be incorporated into the Ni and Ce lattice. The Pt–Ni alloy formation can provide a lower carbon deposition leading to enhance the DRM performance.