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

Abstract

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.