Hydrolysis Of Furfural Residues Via Ionic Liquids Pretreatment

In our country, the effective utilization of biomass wastes is vital to solve the problem of "agriculture, countryside and farmers". There is a large number of furfural, so the furfural residue-a kind of biomass waste is pretty large. Ionic Liquids (ILs) is a kind of molten salt at 100℃, which is composite of organic cations and inorganic anions. Ionic liquid has a good solubility for the organic and inorganic compounds, so-called a new type of ’green solvents’. So, it has a good application on the biomass pretreatment. In this paper, we make an ionic liquid pretreatment on furfural residue.Combined with different heating method and ionic liquid-NaOH (NaOH/H2O2) method, we measured the content change with various components and production rate of reducing sugar in the acid hydrolyzation. As a result, the ionic liquid pretreatment technology is obtained. The main points are summarized as follows:1.In this study, using single-factor method, the optimal conditions of acid hydrolysis of raw furfural residue without pretreatment are obtained: 1:40 of solid-to-liquid ratio;2% of acid concentration; 2h of reaction time; 175℃.The reducing sugar (RS) yield is 20.15%. While do the ionic liquid [Bmim]Cl pretreatment in the oil bath, the optimal conditions are obtained: 30min of reaction time; 140℃; 1:9 of solid-to-liquid ratio. The RS yield is 37.72%. Then, the effect of ionic liquid structure on reducing sugar yield is discussed, with the discovery: pretreatment effects of Cl-is better than Br-, short branched chain is preferable to long one.2. Do the ionic liquid-[Bmim]Cl, pretreatment under different heating methods. The optimal conditions under ultrasound are obtained: 30min of reaction time; 1:9 of solid-to-liquid ratio. The RS yield is 40.4%. The optimal conditions under microwave are as follows:500w of reaction power; 80℃The RS yield is 43.2%. The results show that the pretreatment efficiency are as follows: microwave> ultrasound> oil bath.3. Make the [Bmim]Cl ionic liquid pretreatment combined with alkaline(NaOH/H2O2). The conclusions are as follows: For the individual pretreatment efficiency, NaOH/H2O2> NaOH>[Bmim]Cl. All of them are far better than the furfural residue without pretreatment. For the combined pretreatment efficiency, NaOH/H2O2-[Bmim]Cl is the best, with 50.4% of RS yield. And all the combined pretreatments efficiency are better than individual pretreatments. In the pretreatment sequence, the method of NaOH (NaOH/H2O2) pretreatment firstly, [Bmim]Cl pretreatment secondly is better than the one of the inversed order method.4. Using the infrared spectroscopy (IR), scanning electron microscopy (SEM),X-ray diffraction spectrum (XRD) and component analysis method, we made an analyzation from below aspects:the morphological structure, physical properties and chemical composition.The results show that after pretreatment, the lignin is reduced via pretreatment to improve the RS yield. The furfural residue with retreatment shows rough and loose, the phenomenon of crushing and cracking stratified is clearly, particle size decreased, particle porosity increased.This structure shows that the liquid sulfuric acid can be more readily accessible into the furfural residue, and increases the efficiency of the RS yield.