The conversion of technical lignin into valuable chemicals is important for the complete utilization of lignocellulose. The kraft process dominates the pulp industry, and large amounts of kraft lignin are produced worldwide. However, the complexity of lignin limits its valorization. In this study, a kraft lignin, Indulin AT, was depolymerized under base conditions, and the effects of substrate loading, NaOH concentration, temperature, and hydrogen peroxide on depolymerization were investigated. The production of aromatic monomers is favored by a continuous flow process, even with a very short reaction time (2 min vs. 30 min in a batch reactor). Higher temperature and NaOH concentration led to a higher degree of depolymerization, and thus more guaiacol and vanillin. A guaiacol yield of 5.1% was obtained after depolymerization of 5 wt% of lignin and 2 wt% of NaOH at 200 °C with a residence time of 2 min. When taking the whole operation, including the cost and depolymerization efficiency, into consideration, the concentration, lignin loading of 4 wt% of lignin, NaOH concentration of 2 wt%, and the temperature of 210 °C were chosen as the optimal conditions for the production of a guaiacol-rich fraction. The permeate obtained by ultrafiltration of the depolymerized Indulin AT sample contained a higher amount of guaiacol, which was quantitatively converted to muconic acid using an engineered strain of Pseudomonas putida KT2440. The three-step process in this work involves base-catalyzed depolymerization, ultrafiltration, and biological conversion represent an efficient approach to convert Indulin AT lignin into muconic acid.

将工业木质素转化为有价值的化学品对于木质纤维素的完全利用非常重要。牛皮纸工艺在纸浆工业中占主导地位，世界范围内生产了大量的牛皮纸木质素。然而，木质素的复杂性限制了其价值。在这项研究中，硫酸盐木质素 Indulin AT 在碱性条件下解聚，并研究了底物负载、NaOH 浓度、温度和过氧化氢对解聚的影响。连续流动工艺有利于芳族单体的生产，即使反应时间非常短（在间歇式反应器中为 2 分钟对 30 分钟）。更高的温度和 NaOH 浓度导致更高程度的解聚，从而导致更多愈创木酚和香草醛。愈创木酚收率为 5。在 200°C 下将 5wt% 的木质素和 2wt% 的 NaOH 解聚后得到 1%，停留时间为 2 分钟。综合考虑成本和解聚效率等整个操作，选择木质素浓度、木质素负载量为4wt%、NaOH浓度为2wt%、温度210℃为最佳条件。生产富含愈创木酚的部分。通过超滤解聚的 Indulin AT 样品获得的渗透液含有较高量的愈创木酚，使用工程菌株将其定量转化为粘康酸 选择 2 wt% 的 NaOH 浓度和 210 °C 的温度作为生产富含愈创木酚馏分的最佳条件。通过超滤解聚的 Indulin AT 样品获得的渗透液含有较高量的愈创木酚，使用工程菌株将其定量转化为粘康酸 选择 2 wt% 的 NaOH 浓度和 210 °C 的温度作为生产富含愈创木酚馏分的最佳条件。通过超滤解聚的 Indulin AT 样品获得的渗透液含有较高量的愈创木酚，使用工程菌株将其定量转化为粘康酸恶臭假单胞菌KT2440。这项工作中的三步过程涉及碱催化解聚、超滤和生物转化，是将 Indulin AT 木质素转化为粘康酸的有效方法。