亚/超临界乙醇中玉米秸秆水提取物的反应机理研究

Reaction pathway and mechanism of cornstalk water soluble extracts in sub-and super-critical ethanol

【目的】建立玉米秸秆水提取物在亚/超临界乙醇中反应后各集总组分之间的主要反应路径图,并考查反应过程中乙醇对产物的影响机理。【方法】用容量为1 L的间歇式反应试验装置,取玉米秸秆水溶性提取物在乙醇中进行反应,利用集总的方法将玉米秸秆水溶性有机物和产物归总为气体、易挥发物、轻油、重油、固体物(不溶于水和丙酮)5个集总组分,研究反应温度从140℃上升至300℃,及在300℃条件下反应过程中各集总组分的分布规律。【结果】玉米秸秆水溶性提取物在亚/超临界乙醇条件下,主要生成了挥发物、气体、固体物和重油,其中挥发物与固体物之间存在着可逆反应,固体物在亚/超临界乙醇的作用下又可进一步反应转化成挥发物,重油在液化过程中生成较少,在整个反应过程中最高收率为9.46%。【结论】乙醇在液化过程中除起到传热作用和充当反应溶剂的作用外,还为反应过程提供自由基,对产物具有重整作用。

【Objective】 The lumping models of reaction of cornstalk water soluble extracts in sub-and super-critical ethanol were established,and the main function of ethanol was investigated.【Method】 Reaction of cornstalk water soluble extracts in sub-and super-critical ethanol was investigated using a 1 L stainless-steel autoclave.The five lumping models of reaction of cornstalk water soluble extracts in sub-and super-critical ethanol,gas,water-soluble organic matter,heavy oil,volatile organic compounds and residue were established to study their distribution pattern when the reaction temperature rose from 140 ℃ to 300 ℃ and remained 300 ℃.【Result】 The main products were gas,volatile organic compounds,a little heavy oil and residue;the reaction of residue and volatile organic compounds showed a reversible reaction;Secondary reaction of residue under conditions of sub-and super-critical ethanol were transformed into volatile organic;the heavy oil generated was very little,the highest extracting rate was 9.46%.【Conclusion】 The main function of ethanol was assumed to refine heat transfer,solvent and supply of radicals,and these radicals were able to restructure the products of liquefaction.