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Method for preparing syringaldehyde by oxidative degradation of lignin

A technology of oxidative degradation and syringaldehyde, which is applied to the preparation of carbon-based compounds, chemical instruments and methods, and the preparation of organic compounds, can solve the problems of difficult separation and industrialization of oxidative degradation of lignin, and achieve cost reduction and high efficiency. The effect of value-added industrialization development and promoting the sustainable development of agriculture

Inactive Publication Date: 2011-08-10
JIANGNAN UNIV
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  • Abstract
  • Description
  • Claims
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Problems solved by technology

However, because the oxidative degradation products of lignin, syringaldehyde, vanillin, and p-hydroxybenzaldehyde are very similar in structure, only differ in the number of methoxyl groups, and their physical and chemical properties are very similar, so it is difficult to separate them. The industrialized separation method makes it difficult to industrialize the oxidative degradation of lignin

Method used

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  • Method for preparing syringaldehyde by oxidative degradation of lignin
  • Method for preparing syringaldehyde by oxidative degradation of lignin

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Embodiment 1

[0039] Put 2mol / L NaOH aqueous solution into the reaction kettle, add 60g / L lignocellulose enzymatic residue (Klasen lignin content is 40%), pass through 0.2Mpa nitrogen protection, start heating, after reaching the reaction temperature of 120°C , feed nitrogen to make the total pressure reach 1.5MPa, then quickly switch to oxygen, adjust the total pressure to 2.0Mpa, and start stirring at the same time, the stirring speed is 1000rpm, this time is set as the "zero point" of the reaction, and the reaction ends after 90min. The yield of vanillin was 11.5% (p-klasen lignin), the yield of syringaldehyde was 18.2% (p-lignin), and the yield of p-hydroxybenzaldehyde was 6.5% (p-klasen lignin).

[0040] After the reaction, the reaction solution was centrifuged at 4000 rpm and the centrifugation time was 2 minutes; the centrifuged solution was acidified with 20% sulfuric acid to a pH of about 2-3, precipitated overnight, filtered, and vacuum-dried at 50°C for 24 hours to obtain a yellow...

Embodiment 2

[0045] Put 3.0mol / L NaOH aqueous solution into the reactor, add 180g / L alkali lignin (Klasen lignin content is 90%), and drop 5g / L LaMn 0.7 Cu 0.3 o 3 Catalyst (self-made, preparation method is as follows: the required nitrate of molecular formula is dissolved in water and makes nitrate solution, adds citric acid and makes complexing agent solution in nitrate solution, the total amount of metal ions in citric acid and nitrate solution The molar ratio is 1: 1.5; the pH value of the complexing agent solution is adjusted to 5-6 by dripping ammonia water with a concentration of 10% in the complexing agent solution, and stirring and heating the complexing agent solution after adding the ammonia water to obtain wet condensation glue; the heating temperature is 80°C, the stirring speed is 200 rpm, and the stirring time is 8 hours). Introduce nitrogen protection of 0.1MPa, start heating, and after reaching 160°C, inject nitrogen to make the total pressure reach 2.0Mpa, then quickly ...

Embodiment 3

[0051] Put 0.2mol / L NaOH aqueous solution into the reactor, add 10g / L sulfonated lignin (Klasen lignin content is 92%), and put 100g / L CuO catalyst (chemically pure, purchased). Introduce nitrogen protection of 0.1MPa, start heating, after reaching 180°C, inject nitrogen to make the total pressure reach 2.0MPa, then quickly switch to oxygen, adjust the total pressure to 4.0Mpa, and start stirring at the same time, this time is defined as the "zero point of the reaction" ", the reaction ends after 30min. The yield of vanillin was 20.3%, the yield of syringaldehyde was 11.1%, and the yield of p-hydroxybenzaldehyde was 7.5%, all of which were calculated according to Klassen to lignin.

[0052] After the reaction, centrifuge the reaction liquid at 2000rpm and centrifuge for 10 minutes; add 20% sulfuric acid to the centrifuged liquid to acidify to a pH of about 2-3, precipitate overnight, filter, and vacuum-dry the precipitate at 50°C for 24 hours to obtain a yellow color solid. ...

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Abstract

The invention relates to a method for preparing syringaldehyde by oxidative degradation of lignin, which comprises the following steps of: 1) dissolving an oxidative degradation product solid of the lignin by using an organic solvent, adding ammonia water to obtain a syringaldehyde and ammonia water complex precipitate, performing centrifugal separation, and acidifying the complex precipitate to obtain syringaldehyde; and 2) evaporating to dryness under reduced pressure and centrifuging to obtain ammonia water mixed solution, performing bromination on the obtained solid substance and elemental bromine or bromine hydride solution, and performing methoxylation reaction on the bromination product and sodium methoxide under the catalysis of cuprous salt to obtain the syringaldehyde. By the steps, the oxidative degradation product of the lignin is all converted into the same product, namely the syringaldehyde, the yield of the syringaldehyde is 50-60 percent, the utilization rate of lignocellulosic materials is improved, the cost of cellulose alcohol and papermaking industry is reduced, and the method has important meaning for realizing high value-added industrial development of the lignin and industrialization of cellulose ethanol and promoting agricultural sustainable development.

Description

technical field [0001] The invention relates to the technical field of biomass chemical industry, in particular to a method for preparing syringaldehyde by oxidative degradation of lignin. Background technique [0002] In order to alleviate the dual pressure of energy and environment in the future, countries all over the world attach great importance to the development and utilization of renewable resources, especially biomass resources. Biomass resources, as an ideal substitute for fossil resources such as petroleum and coal, have attracted widespread attention around the world. Biomass resources can be used as energy and processed into chemicals. Therefore, how to efficiently convert biomass resources into energy and chemicals is one of the current research hotspots. [0003] Plant biomass is an important component of biomass resources, and its main components are cellulose, hemicellulose and lignin. Among them, cellulose and hemicellulose are used to manufacture fuel al...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C47/575C07C45/64C07C45/85
Inventor 邓海波
Owner JIANGNAN UNIV
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