Department of Chemical Engineering, Lund University, SE-21100 Lund, Sweden.
Centre for Analysis and Synthesis, Department of Chemistry, Lund University, SE-22100 Lund, Sweden.
Molecules. 2021 May 13;26(10):2887. doi: 10.3390/molecules26102887.
Base-catalyzed depolymerization of black liquor retentate (BLR) from the kraft pulping process, followed by ultrafiltration, has been suggested as a means of obtaining low-molecular-weight (LMW) compounds. The chemical complexity of BLR, which consists of a mixture of softwood and hardwood lignin that has undergone several kinds of treatment, leads to a complex mixture of LMW compounds, making the separation of components for the formation of value-added chemicals more difficult. Identifying the phenolic compounds in the LMW fractions obtained under different depolymerization conditions is essential for the upgrading process. In this study, a state-of-the-art nontargeted analysis method using ultra-high-performance supercritical fluid chromatography coupled to high-resolution multiple-stage tandem mass spectrometry (UHPSFC/HRMS) combined with a Kendrick mass defect-based classification model was applied to analyze the monomers and oligomers in the LMW fractions separated from BLR samples depolymerized at 170-210 °C. The most common phenolic compound types were dimers, followed by monomers. A second round of depolymerization yielded low amounts of monomers and dimers, while a high number of trimers were formed, thought to be the result of repolymerization.
从 kraft 制浆过程中提取的黑液浓缩物（BLR）经堿催化解聚，然后进行超滤，这被认为是获得低分子量（LMW）化合物的一种方法。BLR 的化学复杂性导致了 LMW 化合物的复杂混合物，其由已经经历了几种处理的软木和硬木木质素的混合物组成，这使得用于形成增值化学品的成分分离更加困难。在不同的解聚条件下获得的 LMW 馏分中鉴定酚类化合物对于升级过程至关重要。在这项研究中，采用了一种最先进的非靶向分析方法，使用超高效超临界流体色谱与高分辨率多级串联质谱（UHPSFC/HRMS）相结合，并结合 Kendrick 质量缺陷分类模型，用于分析从 170-210°C 解聚的 BLR 样品中分离出的 LMW 馏分中的单体和低聚物。最常见的酚类化合物类型是二聚体，其次是单体。第二轮解聚产生的单体和二聚体数量较少，而三聚体数量较多，这被认为是重聚的结果。
