Tuning ZSM-5 acidity via silicalite-sol: A strategy for coke-resistant dry reforming catalysts

CO₂ valorization through dry reforming of methane (DRM) offers a pragmatic way of reducing global warming by converting two greenhouse gases (CO₂ and CH₄), into value-added syn-gas. Developing catalysts with high surface area, tailored porosity, excellent redox properties, enhanced basicity, and well-dispersed nickel nanoparticles with small crystallite sizes is critical to achieving efficient DRM performance. In this study, the acidity and framework properties of MFI zeolite (ZSM-5) were modulated using silicalite seeds at varying ZSM-5/silicalite weight ratios. The resulting materials were impregnated with Ni to prepare coke-resistant DRM catalysts, denoted as Ni-ZS(x). Catalytic evaluations were conducted in a fixed-bed reactor at 750 °C and atmospheric pressure, with Ni-ZS(x) catalysts compared against unmodified Ni-ZSM-5. Among the series, Ni-ZS(0.5) exhibited superior catalytic performance and outperformed unmodified Ni-ZSM-5. Furthermore, the Ni-ZS(0.5) represents a stable catalyst with conversion of CH₄ (82 %) and CO₂ (75 %) at 24 h, having H₂/CO ratio of ∼1.5. The increased activity could be attributed to improved basicity, nickel dispersion and textural properties, elucidated by temperature programmed analysis (CO₂-TPD and H₂-TPR), scanning and transmission electron microscopies (SEM and TEM), N₂-sorption and XRD analysis. The modified catalysts with improved catalytic performance could be of potential interest for industrial purposes towards net zero emission.