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Method for preparing lignin phenolic monomers by depolymerizing lignin

A technology of lignin phenol and lignin, which is applied in ether preparation, chemical instruments and methods, physical/chemical process catalysts, etc., can solve problems such as harsh reaction conditions, lower reaction temperature and pressure, and low efficiency, and achieve product selectivity High efficiency, simple operation process and mild reaction conditions

Pending Publication Date: 2021-02-26
TIANJIN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] However, the conventional RCF reaction is carried out at high temperature (220-250°C) and high pressure (5-12MPa), which not only requires expensive high-pressure reaction equipment, but also generally requires external hydrogen, which makes the production cost high, dangerous and inefficient
In addition, since the raw materials are solids such as wood chips, shavings, and wood blocks, it is difficult to carry out the reaction in a high-pressure reactor under continuous conditions.
Therefore, harsh reaction conditions and low production efficiency greatly limit its industrial application
[0007] At present, the means of improving the process are mainly adding additives (such as acids, alkalis, aldehydes, etc.), using different catalysts (such as Ru / C, Pd / C, supported Ni-based catalysts, etc.) and reaction solvents ( water, methanol, ethanol, butanol, ethylene glycol, dioxane, branched chain hydrocarbons and complex solvents, etc.), the results often can only reduce the reaction temperature and pressure to a certain extent, but cannot Under the condition

Method used

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  • Method for preparing lignin phenolic monomers by depolymerizing lignin
  • Method for preparing lignin phenolic monomers by depolymerizing lignin

Examples

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Embodiment 1

[0023] A method for preparing lignin phenolic monomers by depolymerizing lignin, comprising the following steps: placing 1 g of poplar sawdust and 0.2 g of Ru / C catalyst in 20 ml of ethylene glycol, adding sulfuric acid, and finalizing the sulfuric acid in the ethylene glycol. The concentration is 0.5g / L; under the gauge pressure of 300kPa and 220°C, the reaction is carried out for 0.5h to obtain lignin phenolic monomers.

[0024] The supported mass of Ru in the Ru / C catalyst used in this example was 5%.

[0025] The total yield of propyl guaiacol, propyl eugenol, propyl guaiacol and propyl eugenol was 19.7 wt%, and the selectivity of propyl guaiacol and propyl eugenol was 72.1 wt%.

Embodiment 2

[0027] A method for preparing lignin phenolic monomers by depolymerizing lignin, comprising the following steps: placing 1 g of eucalyptus wood chips and 0.02 g of Ru / C catalyst in 50 ml of ethylene glycol, adding sulfuric acid, and finalizing the sulfuric acid in the ethylene glycol. The concentration is 0.1 g / L; under the gauge pressure of 150 kPa and 200 ° C, the reaction is carried out for 2 h to obtain lignin phenolic monomers.

[0028] The supported mass of Ru in the Ru / C catalyst used in this example was 15%. The total yield of propyl guaiacol, propyl eugenol, propyl guaiacol and propyl eugenol was 22.4 wt%, and the selectivity of propyl guaiacol and propyl eugenol was 88.2 wt%.

Embodiment 3

[0030] A method for preparing lignin phenolic monomers by depolymerizing lignin, comprising the following steps: placing 1 g of willow sawdust and 0.5 g of Ru / C catalyst in 10 ml of ethylene glycol, adding phosphoric acid, and the final concentration of phosphoric acid in the ethylene glycol is 4.0 g / L; under the gauge pressure of 0 kPa and 185 ° C, the reaction is carried out for 6 h to obtain lignin phenolic monomers.

[0031] The supported mass of Ru in the Ru / C catalyst used in this example was 0.5%. The total yield of propyl guaiacol, propyl eugenol, propyl guaiacol and propyl eugenol was 21.8 wt%, and the selectivity of propyl guaiacol and propyl eugenol was 95.1 wt%.

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Abstract

The invention discloses a method for preparing a lignin phenolic monomer by depolymerizing lignin, which comprises the following steps: putting a lignin raw material and a Ru / C catalyst into ethyleneglycol, adding acid, and reacting at the gauge pressure of 0-300 kPa and the temperature of 160-220 DEG C for 0.5-10 hours to obtain the lignin phenolic monomer. According to the invention, high-costhigh-voltage equipment is not needed, and the equipment cost is remarkably reduced; the operation process is simple, and semi-continuous operation can be achieved through material taking and supplementing. The obtained lignin phenolic monomers are propyl guaiacol, propyl syringol, allyl guaiacol and allyl syringol, and mainly comprise propyl guaiacol and propyl syringol, and the content of other phenolic monomer byproducts is extremely low; wherein total selectivity of the obtained four lignin phenol monomer products can reach 95% or above, and the total selectivity of propyl guaiacol and propyl syringol in the four monomers can also reach 95% or above.

Description

technical field [0001] The invention belongs to the field of biomass conversion preparation chemicals, in particular to a method for preparing lignin phenolic monomers by depolymerizing lignin. Background technique [0002] Lignin is one of the main structural components of wood, straw and other plants, and has the characteristics of wide source, large yield and low cost. Lignin is mainly composed of three types of monomers with phenylpropane structure (guaiac group, syringyl group and p-hydroxyphenyl group) which are polymerized and cross-linked. A variety of phenolic monomer chemicals can be prepared by depolymerizing lignin by certain means. In recent years, such transformations have been recognized as a potential means of large-scale production of renewable phenolic monomer chemicals. [0003] There are many depolymerization methods of lignin, such as pyrolysis, hydrothermal liquefaction, acid hydrolysis, hydrogenation depolymerization, catalytic oxidation depolymeriza...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C41/01C07C43/23B01J23/46
CPCC07C41/01B01J23/462C07C43/23
Inventor 齐崴王跃飞任天宇尤生萍苏荣欣
Owner TIANJIN UNIV
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