摘要
以甲酸/水为溶剂,在管式反应器中进行麦草组分的解离,以甲酸/水的共沸质量分数(77.5%)为界设计了含甲酸的两组溶剂组成(甲酸的质量分数分别是72%和90%),以90%甲酸为对照组,探讨了120-140℃温度范围内不同质量分数甲酸处理后纤维素的保留和非纤维素组分(半纤维素和木素)的溶出规律。结果表明,120℃条件下,90%甲酸的脱木素率比72%甲酸脱木素率高15个百分点左右,但更高温度条件下甲酸质量分数对脱木素率影响有限。在相同甲酸质量分数条件下,提高反应温度会导致纤维素的水解,由于管式反应器的传质强化和反应时间的缩短,纤维素水解率低于1.6%。高质量分数甲酸和高处理温度有利于半纤维素的溶出,但同时会导致碳水化合物的脱水降解,从水解液中五碳糖和六碳糖的收率来看,72%甲酸优于90%甲酸的处理效果。另外,水解液中糠醛含量极低,仅占原料中五碳糖理论当量的0.46%~0.99%,这同样归功于管式反应器传质的强化。此实验说明低于共沸浓度的甲酸/水具有促进非纤维素组分溶出和选择性保留纤维素组分的优势。
Formic acid was used to fractionate wheat straw in a tubular reactor. Two concentrations,90% and 72%,above and below the azeotrope of formic acid/water（ 77. 5%）,were applied at temperatures from 120℃ to 140℃. Treatment using 90% formic acid showed a higher lignin removal by 15% than treatment using 72% formic acid at 120℃. However,the positive effect of formic acid concentration on lignin removal was limited for treatments at temperatures higher than 120℃. Hydrolysis of cellulose occurred at elevated treatment temperatures,but the loss of cellulose was lower than 1. 6% due to the application of Tubular reactor as result of enhanced mass transfer and reduced reaction time. Higher treatment severity could enhance the dissolving out of hemicellulose,but also lead to more carbohydrate degradation. Treatments using 72% formic acid were more productive than treatments using 90% formic acid as suggested by the higher yield of hexoses and pentoses in hydrolysate. The furfural formation was only 0. 46% ~0. 99% of theoretical amount of pentoses in wheat straw,due to the application of Tubular reactor. The proposed treatment using formic acid/water below its azeotrope showed effective fractionation of wheat straw with selective remaining of cellulose and enhanced dissolving out of hemicellulose and lignin.
作者
周浩
许家云
庄京顺
王兆江
傅英娟
秦梦华
ZHOU Hao;XU Jia-yun;ZHUANG Jing-shun;WANG Zhao-jiang;FU Ying-juan;QIN Meng-hua(Key Laboratory of Pulp and Paper Science and Technology of the Ministry of Education,Qilu University of Technology（Shandong Academy of Sciences）,Jinan 250353,China;Laboratory of Organic Chemistry,Taishan University,Taian 271021,China)
出处
《造纸科学与技术》
2018年第4期18-21,56,共5页
Paper Science & Technology
基金
国家自然科学基金资助项目(31570571)
关键词
麦草
甲酸
半纤维素
糠醛
wheat straw
formic acid
hemicellulose
furfural
