Efficient Solketal Synthesis via Acetalization Using Sulfonated Carbon From Lavender Leaf Waste After Essential Oil Extraction.

Biomass-based catalyst research is advantageous for the biodiesel industry's sustainability due to the catalysts' readily available raw materials, nontoxic properties, and biodegradability. In this study, sulfonated carbon catalysts were synthesized from lavender biomass residue, obtained after essential oil extraction, through hydrothermal carbonization (HTC) followed by in situ sulfonation, and applied in the acetalization of glycerol with acetone to produce solketal, a bio-based fuel additive. To the best of our knowledge, this type of residue has not yet been explored for this specific application. Characterization by XRD and Fourier-transform infrared spectroscopy (FT-IR) confirmed the amorphous carbon structure and successful incorporation of ─SO3H groups. The formation of solketal was confirmed by nuclear magnetic resonance (NMR) and gas chromatography-mass spectrometry (GC-MS). The catalyst exhibited excellent performance under mild conditions, achieving 97% glycerol conversion and 98% selectivity toward solketal. Optimal conditions (40°C, 30 min, 7.5 wt% catalyst loading, and a glycerol-to-acetone molar ratio of 1:20) afforded high glycerol conversion and selectivity toward solketal. The catalyst exhibited remarkable stability, maintaining >96% conversion and >97% selectivity after seven reuse cycles, confirming the potential of lavender waste as a sustainable precursor for catalyst development. These results highlight the potential of lavender agro-residues as a sustainable carbon source for the production of efficient heterogeneous catalysts in renewable fuel applications.