Abstract
Highly active and recyclable sulfated silica nanocatalyst for the synthesis of hexyl levulinate (HL) is reported. The sulfated catalysts, Sn-BLA (n = 15 or 30 μL of H2SO4 added), are prepared via sulfation upon amorphous bamboo leaf ash (BLA) under non-microwave instant heating condition (100 °C, 1.5 h). The spectroscopy and microscopy results reveal that silica nanoparticles (28 nm) with Brӧnsted (▪ bisulfate group) and Lewis (▪ sulfate group) acid sites are produced upon sulfation treatment. The sulfur containing acid groups covalently bound on the mesosilica surface are very active in the esterification of levulinic acid and hexanol where S30-BLA presents excellent catalytic activity (95.2% conversion, 98.0% selective to HL) at 90 °C for 7 min, which is far more superior than the previously reported catalysts. The S30-BLA catalyst is reusable with slight decrease in catalytic activity after six consecutive runs, suggesting an economical and environment-friendly route to biomass utilization.
The bamboo leaves ash (BLA) biomass has been utilized as a silica source to synthesize sulfated catalyst for the conversion of levulinic acid into hexyl levulinate, a sustainable fuel additive. [Display omitted]
•Highly active sulfated silica nanocatalyst for the synthesis of hexyl levulinate.•S30-BLA exhibits nanospherical shape with a size of 28 ± 7 nm.•Bisulfate and sulfate acid sites active in the esterification of levulinic acid.•Excellent catalytic activity at 90 °C for 7 min by S30-BLA.•Insignificant deterioration in catalytic reactivity after six consecutive runs.