Quan Peng, Kiziltas Alper, Gondaliya Akash, Siahkamari Mohsen, Nejad Mojgan, Xie Xinfeng
College of Forest Resources and Environmental Science, Michigan Technological University, Houghton, Michigan 49931, United States.
Research and Innovation Center, Ford Motor Company, Dearborn, Michigan 48124, United States.
ACS Omega. 2022 May 3;7(19):16705-16715. doi: 10.1021/acsomega.2c01206. eCollection 2022 May 17.
An effective method that can produce a large amount of Kraft lignin with improved homogeneity is strongly desired for Kraft lignin's high-value applications and scientific advancements. Herein, a one-pot acid-catalyzed liquefaction method was developed to recover Kraft lignin directly from black liquor. The recovery rate and properties of the recovered lignin were affected by the reaction time, reaction temperature, moisture content (MC), pH, and acid categories. The highest lignin recovery rate of 75% was achieved when the concentrated black liquor (MC = 25%) reacted with methanol at pH = 7 and 160 °C for 10 min using acetic acid as the catalyst. Most of the recovered lignin from this method showed an average molecular weight (Mw) value less than 2000 Da and a polydispersity (PDI) value less than 2.0. Such a PDI value was lower than that of current acid precipitated lignin (around 2.2-5.4). The recovered lignin was directly used to replace 20% of the petroleum-based polyol in the formula of a flexible polyurethane (PU) foam, and it was found that the molecular weight characteristics of the lignin affected the physical and mechanical properties of the flexible PU foams. The recovered lignin with the Mw value of 1600 Da and the PDI value of 1.8 was able to maintain the major physical and mechanical properties of the flexible PU foams. This study provided a promising way to recover lignin with improved homogeneity from black liquor with the potential to customize lignin properties to meet the requirements of downstream processes.
对于硫酸盐木质素的高价值应用和科学进展而言，强烈需要一种能够生产大量具有更高均一性的硫酸盐木质素的有效方法。在此，开发了一种一锅法酸催化液化方法，以直接从黑液中回收硫酸盐木质素。回收木质素的回收率和性质受反应时间、反应温度、水分含量（MC）、pH值和酸的种类影响。当使用乙酸作为催化剂，浓缩黑液（MC = 25%）在pH = 7和160°C下与甲醇反应10分钟时，实现了最高75%的木质素回收率。通过该方法回收的大部分木质素的平均分子量（Mw）值小于2000 Da，多分散性（PDI）值小于2.0。这样的PDI值低于目前酸沉淀木质素的PDI值（约2.2 - 5.4）。回收的木质素直接用于替代软质聚氨酯（PU）泡沫配方中20%的石油基多元醇，并且发现木质素的分子量特性影响软质PU泡沫的物理和机械性能。Mw值为1600 Da且PDI值为1.8的回收木质素能够保持软质PU泡沫的主要物理和机械性能。本研究提供了一种从黑液中回收具有更高均一性木质素的有前景的方法，并且有潜力定制木质素性质以满足下游工艺的要求。
