Direct Production of Ethyl Levulinate from Carbohydrates Catalyzed by H-ZSM-5 Supported Phosphotungstic Acid

Abstract

A series of supported phosphotungstic acid (H3PW12O40, HPW) catalysts, including HPW/β, HPW/Sn-β, HPW/H-Y, HPW/H-ZSM-5, HPW/USY, HPW/ReUSY, and HPW/SBA-15, were prepared using an impregnation method for alcoholysis of fructose to ethyl levulinate in ethanol. Among these catalysts, HPW/H-ZSM-5 showed the highest catalytic activity, and the yield of ethyl levulinate from fructose increased with increasing phosphotungstic acid loading. The yield of ethyl levulinate reached 43.1% at 160 °C for 2 h over 20 wt.% HPW/H-ZSM-5, and the solid catalyst could be reused at least three times. EL yields of 19.1%, 27.3%, 37.4%, and 8.7% could be obtained from glucose, sucrose, inulin, and cellulose, respectively. Furthermore, the catalysts were characterized by BET surface area, X-ray diffraction, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. HPW/H-ZSM-5 showed good catalytic activity for the direct production of ethyl levulinate from fructose.

Direct Conversion of Carbohydrates into Ethyl Levulinate with Potassium Phosphotungstate as an Efficient Catalyst

“…However, both levulinic acid and furfuryl alcohol need to be prepared from carbohydrates or biomass firstly, and then need to be purified for synthesis of ethyl levulinate. In addition, there is a third route for synthesis of ethyl levulinate that is to be converted from carbohydrates or biomass directly [14][15][16][17]. This route provides a convenient one-pot reaction to produce ethyl levulinate.…”

An alumina‐coated UiO‐66 nanocrystalline solid superacid with high acid density as a catalyst for ethyl levulinate synthesis

“…67 The reason for this phenomenon may have been that EL was converted to γ-valerolactone and 3-(1-ethoxyethoxy)-2-methylbutanal at high temperatures, resulting in a decrease in the EL yield. 75 As time goes on, the deposition of humus on the catalyst surface also inhibits its activity. 76 At reaction temperatures of 160 and 180°C, the EL yield increased steadily as the reaction time increased.…”

“…78 The catalytic performance of SO 4 2− /ZrO 2 @Al 2 O 3 is compared to those reported for hyper-crosslinked polymer-based carbonaceous materials, a hybrid zirconia zeolite, H-ZSM-5-supported phosphotungstic acid (HPW/H-ZSM-5), SO 4 2− /ZrO 2 grafted SBA-15 type double acid solid acid catalyst (SZ/SBA-15), SO 4 2− /ZrO 2 -Al 2 O 3 and sulfonated hydrothermal carbon (HTC-400-S) in Table 2. 16,17,21,75,79,80 The hyper-crosslinked polymer-based carbonaceous materials and hybrid zirconia zeolite were weak catalysts, and the EL yields obtained with the catalysts were 25 mol % (170°C, 8 h) and 21 mol% (230°C, 6 h), respectively. 16,17 HPW/H-ZSM-5 had strong B acid sites, and an EL yield of 19.1 mol% was obtained from a reaction performed at 160°C for 2 h. 75 SZ/SBA-15 had double acidity, and an EL yield of 30.7 mol% was obtained from a reaction performed at 140°C for 24 h. 21 Peng et al used ZrOCl 2 Á8H 2 O and AlCl 3 as raw materials, hydrolyzed them using ammonia and used the coprecipitation method to obtain Al-Zr-type hydroxide gel, which was calcined by sulfuric acid impregnation to prepare SO 4 2 − /ZrO 2 -Al 2 O 3 .…”

Efficient one-pot synthesis of n-butyl levulinate from carbohydrates catalyzed by Fe 2 (SO 4 ) 3

“…were successively examined to improve the conversion of carbohydrates to LA or its esters. Among these acid catalysts, mineral acids are cheap but they are unrecyclable and the discharge of effluent liquor can cause serious environmental pollution [22] . Acidic ionic liquids are effective while the high cost limits their industrial utilization.…”