Method for preventing lignin degradation intermediate product polycondensation

Abstract

The invention discloses a method for preventing lignin degradation intermediate product polycondensation, and relates to the technical field of biomass catalytic conversion. The method comprises the following steps: mixing a biomass raw material with a lignin protective agent, a lignin extraction solvent and an inorganic acid aqueous solution, and carrying out heating, filtering, rotary evaporation, centrifuging and drying to obtain lignin; and mixing the lignin with an amphiphilic heteropolyacid catalyst, a reaction solvent and an oxidizing agent, and carrying out degrading, filtering, extracting, and carrying out rotary evaporation to obtain a lignin degradation product. The lignin degradation monomer prepared by the invention is a highly functionalized aromatic compound and has high additional value; and the yield of the degradation monomer reaches 10-14%, which is far higher than the yield of 2-5% of the conventional lignin oxidative degradation monomer.

Description

technical field [0001] The invention relates to the technical field of biomass catalytic conversion, in particular to a method for preventing polycondensation of lignin degradation intermediate products. Background technique [0002] Lignin is one of the most abundant natural polymers in nature. As a renewable resource, it can replace the problem of resource depletion caused by petroleum-based raw materials, and has attracted more and more attention in related fields such as materials, chemistry, and biology. Lignin, with its high carbon content and high aromaticity, remains the least utilized of lignocellulosic biopolymers despite its great potential as a feedstock for fuel and chemical industries. As the only natural resource in nature that can directly prepare aromatic chemicals, lignin can be degraded under certain conditions to obtain many small molecular compounds. Through further transformation of these small molecular compounds, it can produce high-addition compounds...

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Problems solved by technology

[0004] CN107417498B (2017.12.01) discloses a method for catalyzing the depolymerization of lignin, which uses a solid acid catalyst to degrade lignin, but the degradation temperature used is relatively high (200-300°C), and the intermediate products of lignin degradation are at this temperature It is easy to polycondensate to form refractory oligomers with relatively stable structure, and the yield of lignin monomer is low

[0005] CN105237371B (2017.03.22) discloses a method for preparing vanillin by catalyzing oxidative degradation of lignin. Various heteropolyacids are used to degrade lignin under oxidative conditions, and an aromatic compound with vanillin as the main product is obtained. Hydrocarbon compounds, but the lignin used is ordinary industrial lignin, the structure is quite different from the original lignin structure of plants, and the catalytic system used makes the lignin degradation intermediate products easy to polycondensate, and the yield of the target product is low

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