Stability and activity of nickel catalysts supported on diatomite for dry reforming of methane: Role of cerium and boron promoters

Abstract

This study evaluates the activity and stability of nickel-based catalysts supported on diatomite and promoted with 1 or 2 wt% of cerium or boron for the dry reforming of methane (DRM). Diatomite, a naturally abundant and low-cost support, requires no complex synthesis procedures and remains relatively underexplored in DRM applications. Given the economic viability of using this material, the incorporation of promoters such as cerium and boron can enhance its catalytic properties, including resistance to coke formation, thermal stability, and activity at both low and high temperatures, thereby increasing its potential for industrial application. The support composition was analyzed by X-ray fluorescence (XRF), and its morphology was examined using scanning electron microscopy (SEM). The catalysts were characterized by SEM, X-ray diffraction (XRD), nitrogen physisorption, H₂ temperature-programmed reduction (H₂-TPR), thermogravimetric analysis (TGA), and Raman spectroscopy. The catalytic performance results indicated that cerium addition enhanced CO₂ and CH₄ conversion, with 2 wt% Ce-promoted catalyst stands out due to its significantly higher conversion rates and lower coke formation, as observed in TGA. The 2 wt% boron-promoted catalyst exhibited greater stability, with significant resistance to coke formation, despite showing lower CH₄ conversion. SEM analysis revealed the presence of carbon filaments, particularly in the catalysts without boron, whereas boron-promoted catalysts showed reduced filamentous carbon formation. The activation energies derived from the Arrhenius plot further corroborate these findings, demonstrating that boron-promoted catalysts exhibited satisfactory performance at high temperatures (>800 °C), where the reaction is thermodynamically controlled. In turn, cerium-promoted catalysts achieved superior catalytic performance at ≤ 700 °C and performed similarly to boron-containing catalysts at higher temperatures. Therefore, both promoters imparted distinct properties to the catalysts, yet each contributed to increased stability during DRM through different mechanisms, offering specific advantages depending on the chosen promotion strategy. These findings demonstrate the complementary roles of Ce and B in optimizing catalytic behavior and highlight the potential of diatomite-supported systems for practical DRM applications.