Search

• Phosphotungstic acid improved the levulinic acid production in DESs. • The maximum yield of levulinic acid from glucose was 98.9 %. • The maximum yield of levulinic acid cellulose was 88.6 %. • The kinetics of levulinic acid production from cellulose was investigated. A feasible approach to convert glucose and cellulose to levulinic acid applying phosphotungstic acid as catalyst in deep eutectic solvent was proposed. In our study, phosphotungstic acid was considered to be an effective catalyst for levulinic acid production. A considerable yield of levulinic acid (98.9 %) from glucose was achieved using 30 g/L phosphotungstic acid as catalyst at 468 K for 80 min. The peak levulinic acid yield from cellulose was 88.6 % for 120 min at the present temperature and phosphotungstic acid concentration. The reaction system exhibits efficient performance for the conversion of glucose and cellulose, which was due to the combation of phosphotungstic acid and deep eutectic solvent enhanced the levulinic acid production. Additionally, the kinetic study of levulinic acid formation from cellulose was investigated to supply a further insight on the whole biorefining process. The kinetic model agreed with the experiment data well. The activation energy for levulinic acid formation was 47.2 kJ/mol, which obtained from a modified Arrhenius equation. [ABSTRACT FROM AUTHOR]

• SAPO-18 zeolites with Brønsted and Lewis acid sites were used as bifunctional catalyst. • Brønsted to Lewis acid site ratios were adjusted by modifying the Si/Al ratios. • Lower Brønsted to Lewis acid site ratios enhanced furfural production. • Higher Brønsted to Lewis acid site ratios facilitated levulinic acid formation. • The effect of Brønsted to Lewis acid site ratios on the kinetics was investigated. A one-step process was proposed for valorization of corn stover into furfural and levulinic acid catalyzed by SAPO-18 zeolites. With the aim to produce furfural and levulinic acid, the Brønsted to Lewis acid site ratios of SAPO-18 were modified. The influence of reaction temperature, time and the ratios of Brønsted to Lewis acid site on the valorization of corn stover were investigated. At the fixed catalyst concentration of 20 g/L, a furfural yield of 95.1% was observed at 205 °C for 40 min using SAPO-18 with Brønsted to Lewis acid site ratio of 0.11, and a levulinic acid yield of 70.2% achieved at 190 °C for 80 min using SAPO-18 with Brønsted to Lewis acid site ratio of 0.17. The Brønsted to Lewis acid site ratios of SAPO-18 were adjusted by altering the framework Si/Al ratio of SAPO-18. The SAPO-18 with lower Brønsted to Lewis acid site ratios showed higher activity for furfural production from corn stover and that with higher ratios exhibit superior catalytic effect for levulinic acid formation. The kinetic models considering the effect of Brønsted to Lewis acid site ratios agreed with the experiment values well, which provided detailed insights on the conversion of hemicellulose and cellulose fraction of corn stover into furfural and levulinic acid. [ABSTRACT FROM AUTHOR]