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Lignin extraction and catalytic upgrading from genetically modified poplar
Green Chemistry ( IF 9.3 ) Pub Date : 2017-12-29 00:00:00 , DOI: 10.1039/c7gc03417b Hao Luo 1, 2, 3, 4 , Mahdi M. Abu-Omar 1, 2, 3, 4
Green Chemistry ( IF 9.3 ) Pub Date : 2017-12-29 00:00:00 , DOI: 10.1039/c7gc03417b Hao Luo 1, 2, 3, 4 , Mahdi M. Abu-Omar 1, 2, 3, 4
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Lignin as the only natural resource of aromatics has the potential to be the feedstock of choice for the production of value-added chemicals. However, the recalcitrance of lignin has limited its valorization into value-added products, and it is often burned for heat. The acid-catalyzed organosolv extraction of lignin results in the formation of interunit carbon–carbon bonds, which limit its upgrading. In this work, three different solvent systems (methanol, acetone, and acetic acid) were evaluated for the extraction of native lignin from wild-type and genetically modified poplar species (wild type, high-S, and low-S). Over 68% of the original lignin in the biomass was isolated and subjected to further upgrading over a heterogeneous Ni/C catalyst (10 wt% of catalyst in methanol solvent, under 35 bar H2 pressure at 225 °C). Three major monomeric phenolic products, guaiacol, isoeugenol, and 4-propenyl syringol, were obtained. Methanol-extracted lignin gave the best yield of >60% of the said aromatic products. Methanol as a nucleophile reacted with the Cα benzylic carbocation formed during the organosolv extraction, minimizing the carbon–carbon bond formation. This protection by methanol was demonstrated by NMR spectroscopy. Scanning electron microscopy (SEM) images showed differences in the isolated lignin on the micron scale from the three different treatments.
中文翻译：
转基因杨树木质素的提取和催化提质
木质素作为芳香族化合物的唯一天然资源，有可能成为生产增值化学品的首选原料。但是，木质素的顽固性限制了其在增值产品中的价值，它经常被加热燃烧。木质素的酸催化有机溶剂萃取导致形成单元间碳碳键，从而限制了其升级。在这项工作中，评估了三种不同的溶剂系统（甲醇，丙酮和乙酸），用于从野生型和转基因杨树物种（野生型，高S和低S）中提取天然木质素。分离出生物质中超过68％的原始木质素，并通过多相Ni / C催化剂（在35 bar H 2下在甲醇溶剂中10 wt％的催化剂进行进一步提纯）进行分离225°C时的最高压力）。获得了三种主要的单体酚类产物，愈创木酚，异丁香酚和4-丙烯基丁香酚。甲醇提取的木质素的最佳收率是上述芳香族产品的60％以上。甲醇作为亲核试剂与有机溶剂萃取过程中形成的Cα苄基碳正离子反应，从而最大程度地减少了碳-碳键的形成。通过NMR光谱证明了甲醇的这种保护。扫描电子显微镜（SEM）图像显示了三种不同处理方法分离出的木质素在微米尺度上的差异。
更新日期：2018-02-06
中文翻译：
转基因杨树木质素的提取和催化提质
木质素作为芳香族化合物的唯一天然资源，有可能成为生产增值化学品的首选原料。但是，木质素的顽固性限制了其在增值产品中的价值，它经常被加热燃烧。木质素的酸催化有机溶剂萃取导致形成单元间碳碳键，从而限制了其升级。在这项工作中，评估了三种不同的溶剂系统（甲醇，丙酮和乙酸），用于从野生型和转基因杨树物种（野生型，高S和低S）中提取天然木质素。分离出生物质中超过68％的原始木质素，并通过多相Ni / C催化剂（在35 bar H 2下在甲醇溶剂中10 wt％的催化剂进行进一步提纯）进行分离225°C时的最高压力）。获得了三种主要的单体酚类产物，愈创木酚，异丁香酚和4-丙烯基丁香酚。甲醇提取的木质素的最佳收率是上述芳香族产品的60％以上。甲醇作为亲核试剂与有机溶剂萃取过程中形成的Cα苄基碳正离子反应，从而最大程度地减少了碳-碳键的形成。通过NMR光谱证明了甲醇的这种保护。扫描电子显微镜（SEM）图像显示了三种不同处理方法分离出的木质素在微米尺度上的差异。
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