(569cd) Unveiling the Potential of Desert Sand-Derived Mesoporous Silica Supported Nickel-Based Catalysts for Co-Production of H­2 and Carbon Nanomaterials Via Methane Cracking.

In this research, the aim is to investigates the replacement of a costly commercial silicate source with locally abundant desert sand in the United Arab Emirates (UAE), for synthesizing mesoporous silica. Hydrothermal synthesis methods were employed to develop various mesoporous materials having different pore geometries, namely MCM41-S, SBA15-S and MCF-S, using desert sand as a silica source. These materials were then decorated with 15 wt.% NiO (~13 wt.% Ni) by sono-wet impregnation technique. All Ni-based silica supported catalyst demonstrated enhanced stability at 550 ^oC during the reaction. It was observed that the synthesized MCF-S proves to be a highly efficient catalyst support, as Ni/MCF-S, for the catalytic decomposition of methane (CDM), exhibiting the highest methane conversion (60%), which is 1.4 – 2.1 times higher than the Ni-based classic-structured mesoporous siliceous supported catalysts, such as SBA15-S and MCM41-S. In particular, the H₂ yield (62%) of the Ni/MCF-S catalyst was 1.40 and 2.38 times higher than that of the Ni/SBA15-S and Ni/MCM41-S catalysts, respectively. Detailed characterization techniques, including BET, XRD, SAXS, FTIR, Raman, SEM, TEM, XPS, and H₂-TPR, were employed to analyze siliceous supports, Ni-based catalysts, and spent catalysts. This comprehensive analysis aimed to elucidate the textural, crystallographic, spectral, morphological, chemical, and redox properties of the materials. The results revealed that the macro/mesopores size (4 – 60 nm) and bimodal sinusoidal pore geometry of MCF-S, played a critical role in enhancing Ni particle dispersion, resulting in the highest active Ni metal surface area (7.66 m²/g_cat) and contributing to the improved catalytic activity of Ni/MCF-S in hydrogen production and carbon nanofibers growth.