Glucose Aqueous Isomerization Catalyzed by Basic Ionic Liquids

Abstract

The isomerization of glucose to fructose is a crucial step in the formation of high-value biochemicals from renewable cellulosic biomass. In this work, we have demonstrated a novel and efficient strategy for the aqueous isomerization of glucose catalyzed with basic ionic liquids. At 80 °C and 30 min, a fructose selectivity and yield of 73.8% and 36.8%, respectively, are obtained in the presence of tetrabutyl ammonium proline ([N4,4,4,4]­Pro). Both of these values are notably larger than those obtained in numerous other technologies, making this technique a significant step toward selective generation of fructose. Further investigation reveals that the isomerization performance of glucose is influenced by the structure and hydrophobicity of the ionic liquids, where the latter enhances glucose isomerization via the formation of a microreactor. Moreover, this process exhibits a low activation energy of 34.4 kJ mol–1 with the [N4,4,4,4]­Pro ionic liquid, correlating well with the high activity of this catalytic system. In addition, this IL catalyst shows good reusability as demonstrated by the retention of satisfactory performance after four consecutive runs. Based upon the above results, we have proposed a plausible catalytic mechanism, which can be further confirmed by DFT calculations and isotopic labeling studies.

Glucose Isomerizes to Fructose Catalyzed by the Eco‐Friendly and Biodegradable Ionic Liquids

“…This finding suggests that the isomerization of glucose with a chemical catalyst is feasible. Consequentially, numerous efforts have been made on the isomerization of glucose catalyzed by both heterogeneous and homogeneous materials including Lewis acid, inorganic/organic base, metal salt, and metal‐organic frameworks . However, it is noticeable that, the low hydrothermal stability of Lewis acid and the difficult separation of the homogeneous catalyst from the reaction system hinder the realistic industrial application of the glucose isomerization.…”

“…Figure a and Figure S2a demonstrate that the value of ln(C/C 0 ) linearly relates to the reaction time at the temperature range of from 60 °C to 75 °C. This result suggests that the glucose isomerization in [Ch]Pro aqueous solution is a first order reaction, which is consistent with many previous studies . Therefore, the apparent activation energy of the glucose isomerization is measured according to the Arrehenius formula (Eq.…”

Selective conversion of biomass catalyzed by ionic liquids

“…葡萄糖是纤维素中最基本的结构单元, 其通过 分子间 β-1,4-糖苷键链接形成多糖大分子 [21] . 通过研 究葡萄糖在离子液体中的转化行为, 是阐释纤维素 在离子液体中的溶解与转化过程的常见手段与方法 [22,23] [24][25][26] . 研究结果表明, 在 70-80 ℃的反应温度下, 反 应 30 min, 果糖的选择性均达到 70%以上 [24,25] .…”

“…通过研 究葡萄糖在离子液体中的转化行为, 是阐释纤维素 在离子液体中的溶解与转化过程的常见手段与方法 [22,23] [24][25][26] . 研究结果表明, 在 70-80 ℃的反应温度下, 反 应 30 min, 果糖的选择性均达到 70%以上 [24,25] . 针对 碱性离子液体体系的机理研究表明, 离子液体的碱 性强度与其催化葡萄糖异构化的性能成正比, 且阳 离子对反应的影响要较阴离子大 [24] .…”

Enhanced conversion of glucose to fructose over naturalattapulgite catalyst promoted by CeO2 in water

“…The maximum yield of fructose was obtained 36.4 % over the 10 % CeO 2 /ATP catalyst with the selectivity of 79.1 %, which was similar to that obtained by a basic tetrabutyl ammonium proline ionic liquid. [37] In addition, carbon balance arising from the ratio of carbon moles in formed frucotse and unreacted glucose to those in the initail glucose was counted over the different CeO 2 /ATP catalysts, [34] and the results are also shown in Figure 1.Carbon balance above 90 % was observed over the catalysts with the CeO 2 loading less then 15 %, while higher loading or pure CeO 2 would result in more carbon loss, wherein some byproducts such as humins were inevitable due to the cracking of glucose in the alkaline environment. Recently, potassium permanganate was used for glucose isomerization, and the fructoseyield was achieved to be 29 %.…”