Dual-Acid Mesostructured Cellular Foams (SO3H and Mo) as Efficient Catalysts for Dibenzothiophene Oxidation

Abstract

Mesostructured cellular foam (MCF) materials were modified with sulfonic acid (TPS) and molybdenum species to obtain dual-site catalysts containing both Brønsted and Lewis acid sites. The physicochemical properties of the materials were characterized using N₂ adsorption–desorption, XRD, SEM-EDX, XPS, pyridine adsorption combined with FT-IR and UV–vis spectroscopy. N₂ physisorption revealed that TPS and molybdenum incorporation led to pore blockage and surface area reduction, particularly for Mo/MCF. XRD and SEM-EDX analyses indicated that molybdenum species are well dispersed, although TPS presence promoted localized accumulation, suggesting interactions between the two components. The catalysts were evaluated in dibenzothiophene (DBT) oxidation using H₂O₂. Mo/TPS/MCF exhibited superior activity, achieving 100% DBT conversion within 30 min at 80 °C, outperforming TPS/MCF and Mo/MCF. Moreover, the dual-site catalyst maintained high activity over five consecutive cycles, whereas Mo/MCF showed significant deactivation due to molybdenum leaching. These results demonstrate that TPS plays a stabilizing role for molybdenum species and enhances catalytic performance. The interaction between Brønsted and Lewis acid sites in Mo/TPS/MCF offers a promising strategy for efficient and recyclable oxidative desulfurization catalysts.