【摘要】 以桉木为原料,将桉木经热水预水解后,将预水解液按不同比例循环回用于桉木的预水解,在桉木粉(8 g)与不同水解介质6∶1(m L∶g)的条件下,探讨了循环强化预水解过程中,主要的有机酸(乙酸、甲酸和乙酰丙酸)及总糖的生成和变化情况。结果表明:反应温度190℃,在不同保温时间下,循环强化预水解液中的甲酸和乙酰丙酸浓度随着保温时间的延长而增加,而乙酸浓度则先增加,后期虽有波动,但是稳定在较高水平,而总糖则呈现先增加后下降的趋势;保温时间60 min,在不同预水解温度下,循环强化预水解液中的有机酸和总糖质量浓度随着预水解温度的升高呈现增加的趋势;在上述两种效应研究中,循环比的增大均对循环强化预水解液中的有机酸质量浓度提升有正面效应。循环强化预水解工艺的水解过程自产酸得以富集,利于其资源化利用,而自产酸具有催化水解进程的功能。更多还原

【Abstract】 The generation and variations of organic acids during circulation-enhanced pre-hydrolysis of eucalyptus were in present study. The time effects of eucalyptus circulation-enhanced pre-hydrolysis were examined with a 6 ∶ 1( m L ∶ g) liquid-solid ratio at190 ℃ under varied holding time,and then the hot water pre-hydrolysate obtained under the corresponding conditions was used in the circulation-enhanced pre-hydrolysis process with different ratios. The results showed that formic acid and levulic acid contents in the circulation-enhanced pre-hydrolysate firstly increased with the prolonged time and acetic acid content,and then fluctuated at a relative high level. At the same time,total sugars in pre-hydrolysate show a trend of firstly increasing and then declining. The eucalyptus circulation-enhanced pre-hydrolysis was conducted with a 6 ∶ 1 liquid-solid ratio for 60 min under different temperature,and then the obtained pre-hydrolysates were used in the circulation-enhanced pre-hydrolysis process with different ratios. The results showed that formic acid,acetic acid,levulic acid and total sugars contents in the circulation-enhanced prehydrolysate increased with the increase of hydrolytic temperature. Among the studies mentioned above,organic acid contents increased with the rising of circulation ratio. Enrichment of organic acids during circulation-enhanced pre-hydrolysis process was beneficial for their utilization and their catalytic actions of pre-hydrolysis process.更多还原