Enhancing Aromatic Production from Reductive Lignin Disassembly: in Situ O-Methylation of Phenolic Intermediates

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• 作者：Jacob A. Barrett ; Yu Gao ; Christopher M. Bernt ; Megan Chui ; Anthony T. Tran ; Marcus B. Foston ; Peter. C. Ford
• 刊名：ACS Sustainable Chemistry & Engineering
• 出版年：2016
• 出版时间：December 5, 2016
• 年：2016
• 卷：4
• 期：12
• 页码：6877-6886
• 全文大小：626K
• ISSN：2168-0485

文摘

The selective conversion of lignin into aromatic compounds has the potential to serve as a “green” alternative to the production of petrochemical aromatics. Herein, we evaluate the addition of dimethyl carbonate (DMC) to a biomass conversion system that uses a Cu-doped porous metal oxide (Cu₂₀PMO) catalyst in supercritical methanol (sc-MeOH) to disassemble lignin with little to no char formation. While Cu₂₀PMO catalyzes C–O hydrogenolysis of aryl–ether bonds linking lignin monomers, it also catalyzes arene methylation and hydrogenation, leading to product proliferation. The MeOH/DMC co-solvent system significantly suppresses arene hydrogenation of the phenolic intermediates responsible for much of the undesirable product diversity via O-methylation of phenolic −OH groups to form more stable aryl-OCH₃ species. Consequently, product proliferation was greatly reduced and aromatic yields greatly enhanced with lignin models, 2-methoxy-4-propylphenol, benzyl phenyl ether, and 2-phenoxy-1-phenylethan-1-ol. In addition, organosolv poplar lignin (OPL) was examined as a substrate in the MeOH/DMC co-solvent system. The products were characterized by nuclear magnetic resonance spectroscopy (³¹P, ¹³C, and 2D ¹H–¹³C NMR) and gas chromatography–mass spectrometry techniques. The co-solvent system demonstrated enhanced yields of aromatic products.