Clean production of ethyl levulinate from kitchen waste

A clean and highly efficient catalytic system for the synthesis of ethyl levulinate (EL) from kitchen waste was developed. A heterogeneous catalyst (Sn/ZrPeSO(3)H) was prepared and the Bronsted and Lewis acid sites on the surface of the catalyst were evaluated by pyridine FT-IR. Other physicochemical properties were also characterized using XRD, SEM, FT-IR, XPS, BET, NH3-TPD. The yield of EL obtained was 49.27%, when glucose was used as the starting material and subjected to 170 degrees C for 10 h in the presence of the solid acid catalyst, Sn/ZrPeSO(3)H. The prepared catalyst was also combined with several metal triflates; (Al(OTf)(3), Fe(OTf)(3), Sm(OTf)(3)) to form a catalytic system for the efficient preparation of EL from kitchen waste. Sn/ZrPeSO(3)H/Al(OTf)(3) had superior activity compare to other catalyst combinations. In single factor experiments, the yield of EL reached 52.52% after heating at 170 degrees C for 4 h. In addition, four-factor and three-level experiments were performed using response surface methodology (RSM) to analyze the interaction between each factor. The optimal reaction conditions predicted by the model (163 degrees C, 7.63 h, 20 mg Al(OTf)(3), 40 mg Sn/ZrPeSO(3)H and 79.98 mg of kitchen waste) estimated a maximal yield for EL of 51.24%. The experimental yield of EL however was 52.03% which confirms the reliability of the model. This work provides a cleaner production technology for the synthesis of the high value-added chemical EL, and a sustainable route for the utilization of kitchen waste. (c) 2020 Elsevier Ltd. All rights reserved.