Conversion of water hyacinth Eichhornia crassipes into biofuel intermediate: combination subcritical water and zeolite based catalyst processes

Abstract

The production of gamma-valerolactone, a biofuel intermediate, from water hyacinth is reported in this article. Gamma-valerolactone is an attractive platform chemical that can be further converted into a variety of chemical derivatives for wide use in industrial applications. In this study, we employed a combination of solid acid catalyzed and subcritical water processes to convert hemicellulose and cellulose derived from water hyacinth in levulinic acid, and subsequently followed by catalytic hydrogenation of levulinic acid into gamma-valerolactone. Prior to the catalytic conversion of water hyacinth into levulinic acid and gamma-valerolactone, the lignin content in the water hyacinth was removed by alkali pretreatment using sodium hydroxide solution. The maximum yield of levulinic acid was 173.4 mg/gram dried water hyacinth obtained at 40 bar, 200°C, reaction time of 120 min, and in the presence of acid activated zeolite catalyst. The hydrogenation reactions of levulinic acid into gamma-valerolactone were conducted at 160 to 220°C in the presence of mixed catalysts (Pt/TiO2 and acid activated zeolite). The experimental results indicated that the mixed acid activated zeolite and Pt/TiO2 catalysts gave good performance on the conversion of levulinic acid into gamma-valerolactone (more than 95% conversion).