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以废纸纤维为原料,研究温度、反应时间、原料浓度、反应压力对废纸纤维近临界水解获取5-羟甲基糠醛(5-HMF)的影响,同时考察前驱物六碳糖和水解副产物乙酰丙酸对5-HMF生成和降解的影响。最优水解条件显示:近临界温度为375℃、反应时间为200 s、原料浓度为2.4%、反应压力为19.2 MPa时,获得的5-HMF产率最大,为(10.92±0.51)%。相比原生废纸纤维,其水解残渣的结晶度由69.24%降为57.14%,残渣中仍存在一定量的纤维素,纤维素结晶结构带来的反应屏障是影响5-HMF产率的一个重要因素。
The effects of temperature, reaction time, concentration of raw materials and reaction pressure on the 5-HMF hydrolysis of waste paper fibers were investigated by using waste fiber as raw material. Effect of the product levulinic acid on the formation and degradation of 5-HMF. The optimal hydrolysis conditions showed that the yield of 5-HMF was the highest (10.92 ± 0.51)% when the reaction temperature was 375 ℃, the reaction time was 200 s, the feed concentration was 2.4% and the reaction pressure was 19.2 MPa. The degree of crystallinity of the hydrolyzed residue was reduced from 69.24% to 57.14% compared with that of the primary paper, and a certain amount of cellulose remained in the residue. The reaction barrier caused by the crystalline structure of cellulose was an important factor influencing the yield of 5-HMF factor.