Mild thermolytic solvolysis of technical lignins in polar organic solvents to a crude lignin oil,Sustainable Energy & Fuels

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Mild thermolytic solvolysis of technical lignins in polar organic solvents to a crude lignin oil
Sustainable Energy & Fuels ( IF 5.0 ) Pub Date : 2020-10-19 , DOI: 10.1039/d0se01016b
Panos D. Kouris _{1,

2,

3,

4,

5} , Dannie J. G. P. van Osch _{1,

2,

3,

4,

5} , Geert J. W. Cremers _{1,

2,

3,

4,

5} , Michael D. Boot _{1,

2,

3,

4,

5} , Emiel J. M. Hensen _{1,

2,

3,

4,

5}

Affiliation

A mild thermal solvolysis process using alcohols for the valorization of technical Protobind soda lignin into crude lignin oil (CLO) is presented. The solubilization process results in lower molecular weight lignin fragments (1250–1550 g mol⁻¹ cf. 2500 g mol⁻¹ of parent lignin), while rejecting heavy compounds and other solid impurities. The influence of the reaction temperature (100–350 °C), residence time (0.5–4 h), lignin : solvent ratio (1 : 15–1 : 2 w/v) and alcohol solvent (methanol, ethanol, 1-propanol, 1-butanol, and 1-octanol) on the amount and type of products is investigated. At a high lignin loading (ratio < 1 : 5 w/v) and under optimum conditions for lignin solubilization (T = 200 °C, t = 0.5 h), the condensation reactions and solvent consumption are minimized. Methanol exhibits the highest solvolytic efficacy resulting in an overall lignin solubilization degree of 61 wt%, which includes some heavier lignin fractions originating from condensation reactions. The other alcohols resulted in a lignin solubilization degree of 57 wt% for ethanol, 53 wt% for 1-propanol, 51 wt% for 1-butanol and 38 wt% for 1-octanol. The solvent losses based on GC-MS analysis of the obtained CLOs were 1.1 wt% for methanol, 1.4 wt% for ethanol and 2.2 wt% for 1-butanol. Hansen solubility parameters are employed to discuss the effect of solvent on the solubilization process. Gel permeation chromatography and heteronuclear single quantum coherence NMR of solubilized fractions revealed cleavage of β-O-4 bonds during thermal solvolysis, explaining the molecular weight reduction. Methanol is the most favourable solvent and is utilized in solubilization of 5 different biorefinery lignins. In all cases, this led to CLO with a lower molecular weight of the lignin fragments, a lower polydispersity and an increased hydroxyl group content.

中文翻译：

在极性有机溶剂中将工业木质素温和热解为粗木质素油

提出了一种使用醇的温和热溶剂分解工艺，以将工业级苏打木素木质素转化为粗木质素油（CLO）。溶解过程的结果在低分子量木质素的片段（1250至1550年克摩尔^-1 比照2500克摩尔^-1父木质素的），而拒绝重化合物和其它固体杂质。反应温度（100–350°C），停留时间（0.5–4 h），木质素：溶剂比（1：15-1：2 w / v）和醇溶剂（甲醇，乙醇，1-丙醇）的影响，1-丁醇和1-辛醇）对产品的数量和类型进行了研究。在高木质素负载量（比率<1：5 w / v）下和在木质素增溶的最佳条件下（T = 200°C，t= 0.5 h），缩合反应和溶剂消耗最小。甲醇表现出最高的溶剂分解功效，导致整体木质素溶解度为61 wt％，其中包括源自缩合反应的一些较重的木质素馏分。其他醇导致木质素的溶解度对于乙醇为57重量％，对于1-丙醇为53重量％，对于1-丁醇为51重量％，对于1-辛醇为38重量％。基于所得CLO的GC-MS分析，溶剂损失对于甲醇为1.1重量％，对于乙醇为1.4重量％，对于1-丁醇为2.2重量％。使用Hansen溶解度参数来讨论溶剂对溶解过程的影响。凝胶渗透色谱法和可溶级分的异核单量子相干NMR显示了β- O的裂解热溶剂分解过程中的-4键说明分子量降低。甲醇是最有利的溶剂，可用于溶解5种不同的生物炼油厂木质素。在所有情况下，这导致具有较低分子量的木质素片段，较低的多分散性和增加的羟基含量的CLO。

更新日期：2020-11-06

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