速生杨半纤维素的抽提及其转化为糠醛的研究

Hemicelluloses Extraction from Fast-growing Poplar and Their Conversion into Furfural

本文对速生杨半纤维素的抽提及其转化为糠醛的规律及机理进行了研究。首先建立了半纤维素在稀酸催化条件下的水解/降解动力学模型,以预测不同条件下半纤维素的得率。研究发现,高酸浓和高温有助于提高半纤维素的得率,但同时也会加速纤维素的降解。在优化条件下,半纤维素的抽提得率为91%,而纤维素的损失率低于7%。接着对得到的抽提液转为糠醛进行了研究,结果发现,温度、酸浓、反应时间及其二次项对糠醛的得率及反应选择性有很大的影响。经过优化,在181.0℃、15.0min、硫酸浓度1.0 wt%,戊糖浓度17.9 g/L时,糠醛的最大得率为52.0 mol%,选择性最大值为54.8%。这意味着为进一步提高产物得率和反应选择性,有必要对抽提液进行预处理,设法减少副反应的发生。

Study on the extraction of hemicelluloses from poplar chips and its conversion into furfural was performed in this paper. Kinetic model of pentosan hydrolysis/degradation was developed to predict the yield of pentosic substances. The yield of pentosic substances was favored at high acid concentration and temperature, so was that of hexosans. Under optimal conditions, 91% of pentosan could be recovered, with less than 7% of hexosan released into the extraction liquor. Then conversion of the resultant pentose into furfural was investigated. Results showed that temperature, acid concentration, duration （time） and their second order intercepts had large effects on the yield of furfural and the reaction selectivity. A maximum yield of 52. 0 mol% and a maximum selectivity of 54.8% were obtained under conditions of 181.0℃ , 15.0 min, 1.0 wt% sulfuric acid and 17.9 g/L pentose, which indicated that treatment of extraction prior to conversion was needed to improve furfural yield and reaction selectivity.