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通过直接水解 kraft 木质素生产多元醇:工艺参数的影响。

Production of polyols via direct hydrolysis of kraft lignin: effect of process parameters.

机构信息

Department of Chemical and Biochemical Engineering, Faculty of Engineering, Western University, London, ON, Canada N6A 5B9.

出版信息

Bioresour Technol. 2013 Jul;139:13-20. doi: 10.1016/j.biortech.2013.03.199. Epub 2013 Apr 6.

Abstract

Kraft lignin (KL) was successfully depolymerized into polyols of moderately high hydroxyl number and yield with moderately low weight-average molecular weight (Mw) via direct hydrolysis using NaOH as a catalyst, without any organic solvent/capping agent. The effects of process parameters including reaction temperature, reaction time, NaOH/lignin ratio (w/w) and substrate concentration were investigated and the polyols/depolymerized lignins (DLs) obtained were characterized with GPC-UV, FTIR-ATR, (1)H NMR, Elemental & TOC analyzer. The best operating conditions appeared to be at 250°C, 1h, and NaOH/lignin ratio ≈0.28 with 20 wt.% substrate concentration, leading to <0.5% solid residues and ∼92% yield of DL (aliphatic-hydroxyl number ≈352 mg KOH/mg and Mw≈3310 g/mole), suitable for replacement of polyols in polyurethane foam synthesis. The overall % carbon recovery under the above best conditions was ∼90%. A higher temperature favored reduced Mw of the polyols while a longer reaction time promoted dehydration/condensation reactions.

摘要

Kraft 木质素(KL)在没有任何有机溶剂/封端剂的情况下,成功地通过直接水解用 NaOH 作为催化剂解聚成具有中等羟基数和中等收率、低重均分子量(Mw)的多元醇。考察了反应温度、反应时间、NaOH/木质素比(w/w)和底物浓度等工艺参数的影响,并采用 GPC-UV、FTIR-ATR、(1)H NMR、元素和 TOC 分析仪对所得多元醇/解聚木质素(DL)进行了表征。最佳操作条件似乎为 250°C、1h 和 NaOH/木质素比约 0.28,底物浓度为 20wt.%,导致<0.5%的固体残留物和约 92%的 DL 收率(脂肪族-羟基数约为 352mg KOH/mg,Mw≈3310g/mol),适合替代聚氨酯泡沫合成中的多元醇。在上述最佳条件下,总碳回收率约为 90%。较高的温度有利于降低多元醇的 Mw,而较长的反应时间有利于促进脱水/缩合反应。

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