杂多酸类离子液体催化浮萍水解制备还原糖

以磷钨酸盐离子液体为催化剂研究了温和条件下浮萍的催化水解制备还原糖性能。系统考察了离子液体类型、离子液体结构、催化剂用量、反应温度及反应时间等实验因素对还原糖、葡萄糖、木糖收率的影响。研究结果表明, 磷钨酸盐离子液体具有良好的催化活性, 在反应时间3 h, 反应温度140℃, 催化剂用量0.4 mmol的条件下, 浮萍水解后总还原糖收率可达到79.8%, 其中葡萄糖和木糖收率分别为339.8 mg·g^-1 和62.2 mg·g^-1。浮萍原料与水解残渣的傅里叶变换红外光谱(FT-IR)、热重(TG)、元素分析(EA)对照分析结果表明:浮萍水解后纤维素和半纤维素含量明显下降, 残渣中木质素含量增加, 与分析结果一致。此外, 磷钨酸离子液体在此过程中也表现出优良的重复使用性能, 经简单分离, 可实现循环使用, 5次的重复使用后浮萍转化率未见显著降低, 还原糖收率仍可达70.1%。

Preparation of reducing sugar from duckweed catalyzed by heteropolyacid-based ionic liquids

Reducing sugar was prepared by the hydrolysis of duckweed with a series of acid ionic liquids (ILs). The effects of reaction conditions such as structure of catalyst, dosage of catalyst, reaction temperature, and reaction time on the yield of total reducing sugar were investigated. The results showed that, imidazole phosphotungstic ionic liquids had the good performance in hydrolysis of duckweed. The best yield of total reducing sugar is 79.8% under the condition of 140℃, 3 h, 0.4 mmol IL catalyst. The residue and raw material were characterized by using Fourier transform infrared spectroscopy (FT-IR), thermogravimetric (TG) and elemental analysis (EA). Furthermore, The IL recovered can be used without significant loss of activity after 5 runs (reducing sugar yield of 70.1%).