Butyl levulinate (BL) is a promising new candidate as diesel fuel and fuel additive. In this study, an efficient process for a one-pot synthesis of BL from biomass-derived carbohydrates in butanol medium with the catalysis of metal sulfates was developed. The catalytic activity of a series of metal sulfates for the synthesis of BL from fructose was investigated. Among various metal sulfates, ferric sulfate Fe2(SO4)3 was found to be the most efficient catalyst, which gave a remarkably high BL yield of 62.8 mol% under the conditions of 463 K, 3 h, a catalyst dosage of 5.0 g/L, and fructose concentration of 25 g/L. Different carbohydrates including glucose, cellulose, inulin and sucrose were also used for one-pot synthesis of BL with the catalysis of Fe2(SO4)3, showing the yields of 39.6, 30.5, 56.6 and 50.1 mol%, respectively. In addition, the recycling and reuse of Fe2(SO4)3 was studied by characterizing them using powder X-ray diffraction (XRD), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS). A plausible reaction pathway for the one-pot synthesis of BL from fructose was proposed. This study provides a facile and feasible way for the synthesis of BL from biomass.Download high-res image (128KB)Download full-size imageA new process for one-pot preparation of butyl levulinate from carbohydrates catalyzed by Fe2(SO4)3 was developed, and a higher BL yield of 62.8 mol% was obtained.

Direct production of ethyl levulinate (EL) from glucose catalysed by a liquid acid catalyst (sulfuric acid) and a solid acid zeolite catalyst USY NKF-7 (USY) in ethanol media was investigated in this study. Effects of the initial glucose concentration (CG0), reaction temperature (T), amount of acid catalyst, and water addition on the yields of EL were compared, respectively. The results show that higher yield of EL can be obtained at lower CG0. Higher temperature and acid concentration can accelerate the reaction rate, but the formation rate of the by-products increases more quickly than that of EL. Water addition also can result in the decrease of the yield of EL. Although sulfuric acid is efficient in the production of EL, the USY is more efficient in converting glucose to 5-ethoxymethyl-2-furaldehyde. Moreover, the use of USY can limit the diethyl ether production, and it can be reused for multiple times.

Levulinic acid is considered as a promising green platform chemical derived from biomass. The kinetics of levulinic acid accumulation in the hydrolysis process of wheat straw was investigated in the study. Using dilute sulfuric acid as a catalyst, the kinetic experiments were performed in a temperature range of 190–230°C and an acid concentration range of 1%–5% (by mass). A simple model of first-order series reactions was developed, which provided a satisfactory interpretation of the experimental results. The kinetics of main intermediates including sugar and 5-hydroxymethylfurfural (5-HMF) were also established. The kinetic parameters provided useful information for understanding the hydrolysis process.

The kinetics for production of ethyl levulinate from glucose in ethanol medium was investigated. The experiments were performed in various temperatures (433–473 K) and initial glucose concentrations (0.056–0.168 mol·L−1) with extremely low sulfuric acid as the catalyst. The results show that higher temperature can improve the conversion of glucose to ethyl levulinate, with higher yield of ethyl levulinate (44.79%, by mole) obtained at 473 K for 210 min. The kinetics follows a simplified first-order kinetic model. For the main and side reactions, the values of activation energy are 122.64 and 70.97 kJ·mol−1, and the reaction orders are 0.985 and 0.998, respectively.