Influence of synthesis variables on the physicochemical properties of lignin-derived cryogels for levulinic acid production from oil palm mesocarp fiber

In an era where sustainable biomass conversion is paramount, this research investigates the impact of preparation conditions of H₃PW₁₂O₄₀-Nb₂O₅ supported carbon cryogels on levulinic acid (LA) production via microwave-assisted conversion of oil palm mesocarp fiber. These cryogels offer an energy-efficient, eco-friendly alternative to traditional mineral acid catalysts, forming LA under mild conditions (2 min, <180 °C). The study examines how preparation parameters, including the Brønsted to Lewis acid ratio, calcination, and solvent exchange, influence cryogel properties and LA yield. A maximum LA yield of 20.1 % was achieved, with the optimized cryogel exhibiting a surface area of 57.41 m² g⁻¹ , porosity of 0.13 cm³ g⁻¹ , and medium acid sites of 7.45 mmol g⁻¹ . The balanced distribution of micropores, mesopores, and macropores facilitated larger biomass particle passage, enhancing thermal conductivity and uniform heat transfer. The interplay of Brønsted-Lowry and Lewis acidity (ratio 1.48) fostered a synergistic effect in catalyzing tandem reaction steps, achieving a synergy factor of 2.15. This work highlights the potential of lignin-derived carbon cryogels in revolutionizing fast, safe, and clean biomass conversion to LA, achieving a one-pot conversion efficiency of 88.5 %. Optimizing preparation parameters enhances catalyst properties, improving LA production efficiency and yield. • Sol-gel method used to enhance catalyst performance for levulinic acid production. • Lignin-derived carbon cryogel promotes sustainable levulinic acid production. • Anchoring H 3 PW 12 O 40 and Nb 2 O 5 on lignin-based support achieved catalyst selectivity. • Optimization varied H 3 PW 12 O 40 /Nb 2 O 5 ratio, calcination, and solvent exchange. • Maximum levulinic acid yield of 20.1 % achieved with a synergy factor of 2.15.