Production of Ethyl Levulinate by Cellulose Conversion over a Self-SiO ₂ -Containing Sulfonated Carbon Catalyst Derived from Oil Palm Empty Fruit Bunches

The effort to find sustainable energy solutions has driven the development of sophisticated biofuel additives to enhance fuel performance and reduce emissions. Ethyl levulinate (EL), a promising biofuel additive, faces challenges in achieving efficient production directly from raw lignocellulosic biomass, such as cellulose. In this study, we report a novel self-SiO2-containing sulfonated carbon catalyst (SiO2/SC), synthesized from oil palm empty fruit bunches (OPEFB)─a widely available agricultural waste─through a carbonization and sulfonation process. The catalyst exhibits a moderate specific surface area (SSA) (63.27 m2 g–1), a high −SO3H acid density (0.6 mmol g–1), and a silicon (Si) content of 0.59 at%. The synergistic interaction between self-contained SiO2 (Lewis acid-like sites) and sulfonic groups (Brønsted acid sites) significantly enhances catalytic activity, resulting in a high EL yield of 59.24 mol % from cellulose. This synergistic effect enables an efficient conversion process with a remarkably high-yielding nonmetal sulfonated carbon catalyst. Our findings demonstrate a scalable, cost-effective, and environmentally friendly catalytic system for efficient biomass valorization, advancing the development of next-generation biofuel additives.