Production of vanillin via oxidation depolymerization of lignin over Fe- and Mn-modified TS-1 zeolites.

Converting lignin into specific aromatic chemicals for utilization through depolymerization of lignin is an effective way to achieve high-value applications. There are many depolymerization methods that can do this, but there are problems such as harsh reaction conditions, low depolymerization efficiency and uncontrollable target products that need to be solved. This study reports a novel system for the oxidative depolymerization of alkali lignin using Fe- and Mn- modified TS-1 as a catalyst to assist in the highly selective production of vanillin. We also proposed a possible reaction pathway for the oxidative depolymerization of alkali lignin to produce vanillin catalyzed by Fe-Mn/TS-1 catalyst. The catalytic effects of TS-1, Fe/TS-1, and Fe-Mn/TS-1 catalysts on the oxidative depolymerization of lignin to produce phenolic monomers and vanillin were investigated. The results show that the modified catalysts can effectively improve the efficiency of linkage bond breaking in lignin, especially the ß-O-4 bond, in which the inter-band transitions of Fe and Mn play an important role. The synergistic effect of the bimetallic-loaded catalyst (Fe-Mn/TS-1) could catalyze the oxidative depolymerization of lignin more efficiently than the monometallic-loaded catalyst (Fe/TS-1). This lignin oxidative depolymerization system produced 40.59 wt% bio-oil including 12.24 wt% phenolic monomers and 16.17 wt% re-lignin after the addition of Fe-Mn/TS-1 catalyst, owning the highest phenolic monomer yield. Surprisingly, this lignin oxidative depolymerization system exhibited high yield for vanillin (8.36 wt%) production. These results demonstrated that the Fe-Mn/TS-1 catalytic system has potential to produce vanillin from lignin under mild conditions.

Recent advances in lignin-based 3D printing materials: A mini-review.

With the growing global population and rapid economic development, the demand for energy and raw materials is increasing, and the supply of fossil resources as the main source of energy and raw materials has reached a critical juncture. However, our overexploitation and overconsumption of fossil resources have led to serious problems, including environmental pollution, climate change, and ecosystem destruction. In the face of these challenges, we must recognize the negative impacts of the shortage of fossil resources and actively seek sustainable alternative sources of energy and resources to protect our environment and sustainable development in the future. Three-dimensional (3D) printing, an additive manufacturing technology, has been used in many fields to manufacture complex and high-precision products. While traditional manufacturing processes typically produce large amounts of waste and emissions that are harmful to the environment, 3D printing is much more energy efficient compared to traditional manufacturing methods, which helps to lower energy costs and reduce reliance on non-renewable energy sources. The development of low-carbon and environmentally friendly 3D printing materials can help to reduce carbon emissions and environmental pollution and realize the goal of sustainable development. Lignin, as the second largest renewable green biomass resource after cellulose, has great potential for manufacturing low-carbon and environmentally friendly 3D printing materials. This review presents some recent studies on the applications of lignin and its derivatives in photo-curing 3D printing, including the preparation and performance of lignin-based photosensitive prepolymers, lignin-based reactive diluents, lignin-based photo-initiators, and lignin-based additive. This review also provides recent studies on the preparation and performance of lignin-based thermoplastic polymer for Fused Deposition Modeling (FDM) 3D printing. Finally, the future challenges and industrialization prospects of lignin-based 3D printing materials are discussed.