Method for preparing p-coumarate by catalyzing lignin depolymerization through hierarchical pore molecular sieve loaded molybdenum oxide

Abstract

The invention discloses a method for preparing p-coumarate by catalyzing lignin depolymerization through hierarchical pore molecular sieve loaded molybdenum oxide. The method comprises the following steps: by taking lignin as a raw material, adding a reaction medium and a hierarchical pore molecular sieve loaded molybdenum oxide catalyst, replacing with nitrogen, pressurizing to 0.1-1MPa, heatingto 120-160 DEG C, reacting for 2-10 hours while stirring, removing the catalyst after the reaction, and catalytically degrading the lignin into p-coumarate. By regulating and controlling the catalyststructure, the reaction medium and the reaction condition factors, high-yield and high-selectivity depolymerization of lignin is achieved, p-coumarate serving as a high-added-value chemical is obtained, and the purpose of high-valued utilization of lignin is achieved. The heterogeneous catalyst is used, the process is simple, reaction conditions are mild, lignin can be selectively converted to obtain the target product p-coumarate, and the yield and selectivity of p-coumarate can reach up to 11.78 wt.% and 85.24 wt.% respectively.

Description

technical field [0001] The present invention relates to lignin depolymerization, in particular to a method for preparing p-coumaric acid ester by molybdenum oxide supported by multi-stage pore molecular sieves by catalyzing lignin depolymerization, which belongs to the high-efficiency utilization technology of agricultural and forestry waste and the high-value utilization of renewable resources field. Background technique [0002] Utilizing the only renewable resource that contains fixed carbon—biomass to prepare high value-added chemicals can reduce the dependence of modern chemical industry on fossil resources and alleviate the development bottleneck caused by the dwindling reserves of fossil resources. At the same time, the use of "carbon-neutral" biomass resources can help alleviate a series of environmental problems such as the greenhouse effect caused by the excessive use of fossil resources. As the most abundant natural phenolic polymer macromolecule in nature, ligni...

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Problems solved by technology

However, this technology uses lignin hydrogenation to realize lignin depolymerization. In the reaction process, it is necessary to use relatively expensive hydrogen to provide hydrogen source, and the reaction conditions are relatively harsh. The reaction temperature reaches 280°C and the hydrogen pressure reaches 8MPa.

[0006] In recent years, Li et al. (Z.M.Li, X.H.Li, Selective catalytic tailoring of the Hunit in herbaceous lignin for methyl p-hydroxycinnamate production overmetal-based ionic liquids, Green Chem., 2018, 20, 3743-3752) utilized homogeneous catalysts Metal-based ionic liquids [Bmim][FeCl 4 ] catalyzed the depolymerization of organic solvent-based bagasse lignin, under the optimal reaction conditions of reaction temperature 145°C, reaction time 6h, and nitrogen pressure 0.5MPa, a chemical with methyl p-coumarate as the main product was obtained, p-coumarin Acid methyl ester yield is 7.1wt.%, selectivity 70.5%, but this technology adopts homogeneous catalyst, and catalyst is difficult to separate and recycle, and industrial application is limited

Chinese invention patent application 201911410781.0 uses commercially available copper chloride, copper sulfate, and copper bromide as catalysts to catalyze the depolymerization of lignin into chemicals whose main product is methyl p-coumarate, but the conversion rate of lignin is low

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