目前,纤维素水解产生可发酵糖的效率很低,是纤维素-乙醇转化的瓶颈问题.拟以化学改性的方法改变纤维素结晶结构从而提高其水解效率.首先以三聚氰氯(TCT)、苯胺为原料,合成2-氯-4,6-二苯氨基-1,3,5-三嗪(DACT),通过红外光谱、核磁共振谱图表征其结构.将DACT用于微晶纤维素羟基的修饰,并将修饰后的纤维素于50℃、固液比为1∶20(W/V)比为条件下用70 wt%硫酸水解60 min,研究DACT用量对纤维素结晶结构和水解性能的影响.水解实验结果表明DACT的相对物质的量的百分含量(以葡萄糖环计)为30%左右时,改性纤维素经酸催化水解后还原糖得率最高,广角X射线衍射证实该水解结果可归因于化学改性令纤维素的结晶结构发生变化,利于纤维素水解产生可发酵糖.
The low yield of fermentable sugar of hydrolysis of cellulose is the bottle-neck problem in conversion of cellulose-ethanol.The aim of this paper is to improve the yield of hydrolysis by the crystal structural change of cellulose based on chemical modification.A new 1,3,5-triazine derivative 2-chloro-4,6-dianilino-1,3,5-triazine(DACT) was synthesized from 2,4,6-trichloro-1,3,5-triazine(TCT) and aniline.The structure of DACT was characterized by IR and 1H NMR spectra.Microcrystalline cellulose(MCC) was chemically modified with DACT and the modified MCC were hydrolyzed to study the impact of the amount of DACT on the crystal structure and the hydrolysis property of cellulose.The hydrolytic conditions were as follows: the concentration of sulfur acid was 70%,the solid to liquid ratio was 1∶10(W/V),the temperature was 50 ℃ and the hydrolysis time was 60 min.The result showed that when the relative molar percentage of DACT(by the cellulosic glucose ring) was about 30%,the yield of the reducing sugar was the highest.The WAXD spectra confirmed that this result was due to the change of the crystalline structure of cellulose by chemical modification,which was beneficial for the hydrolysis of cellulose.