Continuous-Flow Process for the Purification and Fractionation of Alkali and Organosolv Lignins
Continuous-Flow Process for the Purification and Fractionation of Alkali and Organosolv Lignins
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DOI：
10.1021/acssuschemeng.6b01560
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发表时间：
2016-12-01
影响因子：
8.4
通讯作者：
Thies, Mark C.
中科院分区：
文献类型：
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作者：
Klett, Adam S.;Payne, Mark;Thies, Mark C.
热乙酸-水混合物可通过热酸木质素水净化（ALPHA）工艺对碱（kraft）和有机溶剂木质素进行净化和分馏。然而，在高温（例如60-100℃）操作下，在溶剂化的、富含木质素的液体馏分中会发生缩聚反应，显著增加木质素的分子量。因此，研究了α转化为连续流操作，以确定减少停留时间对上述反应和从溶剂化木质素中提取金属到溶剂相的影响。所研究的四种木质素都可以在室温下转化为均匀的木质素水浆，便于连续操作。当混合和平衡装置使用静态混合器时，将停留时间减少到20-30，基本上消除了缩聚反应。例如，连续处理木质素馏分的分子量保持不变，但在相同ALPHA条件下进行间歇处理时，木质素馏分的分子量从7900增加到13200。此外，金属含量减少了10倍(例如，钠含量从1400降至
Hot acetic acid-water mixtures can be used to purify and fractionate alkali (kraft) and organosolv lignins via the Aqueous Lignin Purification with Hot Acids (ALPHA) process. However, condensation polymerization reactions can occur in the solvated, lignin-rich liquid fraction at the elevated temperatures (e.g., 60-100 degrees C) of operation, significantly increasing the lignin molecular weight. Thus, conversion of ALPHA to continuous-flow operation was investigated in order to determine the effect of reduced residence times on both the above reactions and on the extraction of metals from the solvated lignin to the solvent phase. All four lignins investigated could be converted to a homogeneous lignin water slurry at ambient temperatures, facilitating continuous operation. When a static mixer is used for the mixing and equilibration device, reducing residence times to 20-30 condensation polymerization reactions are essentially eliminated. For example, the molecular weight of the lignin fraction remained unchanged with continuous processing but increased from 7900 to 13200 when batch processing was used for the same ALPHA conditions. Furthermore, the 10-fold reduction in metals content (e.g., sodium content reduced from 1400 to