论文部分内容阅读
本文采用循环式反应器研究了杂交杨木纤维中聚戊糖和聚己糖在稀酸条件下的催化分离,分别得出了聚戊糖和聚己糖稀酸水解/降解的动力学模型,以预测在不同反应条件下戊糖和己糖的水解得率。反应条件为温度140～170℃,硫酸浓度0.1%～0.9%wt,液比为6∶1。研究发现,较高的酸浓和温度对提高戊糖和己糖的得率都有利,但相同条件下聚戊糖的反应活性更高。经动力学模型优化得出,在较佳条件下有91%的聚戊糖可以以单体、低聚体及其降解产物的形式从杨木纤维中分离出来,同时超过93%的聚己糖可以以固体的形式保留在纤维中。研究表明,在适宜的稀酸催化条件下杂交杨木纤维中的碳水化合物可以得到很好的分离,为下一步戊糖和聚己糖的分别单独转化打下了基础,不仅可以充分利用木材生物质资源,而且为反应提供了相对均一的条件,从而提高反应选择性和产物的纯度。
In this paper, a cyclic reactor was used to study the catalytic separation of pentose and polyhexose in hybrid poplar fiber under dilute acid conditions. The kinetic models for hydrolyzing / degrading dilute acids of pentose and polyhexose The rate of hydrolysis of pentose and hexose was predicted under different reaction conditions. The reaction conditions are the temperature of 140 ~ 170 ℃, the concentration of sulfuric acid 0.1% ~ 0.9% wt, liquid ratio of 6: 1. The study found that higher acid concentration and temperature are beneficial to improve the yield of pentose and hexose, but under the same conditions, pentose is more reactive. Optimized by the kinetic model, 91% of the poly-pentose can be separated from the poplar fiber in the form of monomers, oligomers and their degradation products under the optimal conditions, while over 93% of the polyhexose It can remain in the form of a solid in the fiber. The results showed that the carbohydrates in hybrid poplar fiber could be well separated under the appropriate dilute acid catalysis, which laid the foundation for the next separate conversion of pentose and polyhexose respectively, which not only can make full use of wood biomass Resources, but also provides a relatively uniform conditions for the reaction, thereby increasing reaction selectivity and product purity.