Stable dry reforming of methane over Ni-Pt bimetallic catalysts supported on KIT-5 in a continuous flow system

Nanostructured bimetallic Ni-Pt catalysts supported on KIT-5 mesoporous silica were developed and assessed for their efficiency in the continuous dry reforming of methane (DRM) to generate synthesis gas. Both monometallic variants (Ni/KIT-5 and Pt/KIT-5) and a range of bimetallic Ni-Pt/KIT-5 catalysts were synthesized using co-impregnation and sequential impregnation methods. Comprehensive characterization of the catalysts was conducted through techniques such as high-resolution scanning electron microscopy (HR-SEM), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) surface area analysis, thermogravimetric analysis (TGA), and Fourier-transform infrared spectroscopy (FT-IR). In the monometallic Ni-based catalysts, nickel primarily existed in the form of NiO. In contrast, the bimetallic catalysts exhibited surface species such as Ni₂O₃ and NiPt₂O4. In the bimetallic Ni-Pt catalysts, thermally stable PtO₂ and NiPt₂O₄ phases were identified. Reduction in hydrogen led to the development of Ni-Pt alloy phases on the surface, which enhanced the overall catalytic performance. The bimetallic Ni-Pt catalysts outperformed their monometallic counterparts in DRM activity. The nanofibrous structure of KIT-5, characterized by its interconnected pore network, provided improved accessibility to active sites and facilitated efficient diffusion of reactants and products. Among the catalysts evaluated, the 9.5%Ni-0.5%Pt/KIT-5 composition achieved the highest conversions of both methane and carbon dioxide, while maintaining a relatively low H₂/CO product ratio. Durability assessments at 700 °C over a period of six hours demonstrated high thermal stability and negligible deactivation due to carbon deposition. Post-reaction analyses of the spent catalysts using XRD and HR-SEM revealed minimal structural deterioration. TGA measurements indicated that carbon deposition resulted in approximately 10% weight loss, suggesting the presence of mainly amorphous carbon and confirming the catalyst's excellent resistance to coking. The fibrous architecture of KIT-5 effectively suppressed nickel particle sintering and carbon build-up. These findings underscore the potential of Ni-Pt/KIT-5 systems, particularly with optimized metal loadings, as robust and coke-resistant catalysts for syngas production via dry reforming of methane.