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A method for degrading lignin in papermaking black liquor

A technology for papermaking black liquor and lignin, which is applied in the field of lignin resource utilization, can solve the problems of no specific solution for the separation of aromatic products, difficulty in industrially large-scale processing of papermaking black liquor, harsh degradation conditions, etc. Conducive to large-scale industrial processing, improving utilization efficiency and service life, and good reusability

Active Publication Date: 2021-02-05
HUNAN NORMAL UNIVERSITY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In the existing literature and reports, the degradation conditions of lignin are harsh (high temperature and high pressure), the equipment is vulnerable (strong acid and strong alkali), it is difficult to realize large-scale industrial treatment of papermaking black liquor, and at the same time, there is no specific solution for the separation of aromatic products method

Method used

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  • A method for degrading lignin in papermaking black liquor
  • A method for degrading lignin in papermaking black liquor
  • A method for degrading lignin in papermaking black liquor

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0030] Embodiment 1 (extraction of lignin in papermaking black liquor)

[0031] (Example 1.1) Papermaking black liquor 1L, add concentrated hydrochloric acid while stirring to adjust the pH to 2, stir at 70°C for 4h, centrifuge to take the lower layer slurry, add alkali to adjust the pH to 13, stir for 2h, filter, add hydrochloric acid to the filtrate to adjust the pH to 2. Stir for 2 hours, filter, wash the solid with water until neutral, and dry at 105°C to obtain lignin.

[0032] (Example 1.2) 1L of papermaking black liquor, add concentrated hydrochloric acid while stirring to adjust the pH to 1, stir at 60°C for 4h, centrifuge to take the lower layer of slurry, add alkali to adjust the pH to 12, stir for 2h, filter, add hydrochloric acid to the filtrate to adjust the pH to 3. Stir for 2 hours, filter, wash the solid with water until neutral, and dry at 105°C to obtain lignin.

[0033] (Example 1.3) 1L of papermaking black liquor, add concentrated hydrochloric acid while s...

Embodiment 2

[0034] Embodiment 2 (catalyst preparation)

[0035] 9gNa 2 WO 4 2H 2 Dissolve O in 8mL water, heat to boiling, add 2.8gNa 2 HPO 4 12H 2 O, continue to react for 30min, slowly add 7.5mL of concentrated hydrochloric acid dropwise, cool to room temperature, filter, dissolve the solid in 4.5mL of water, pour into a separatory funnel, add 10mL of ether, shake, let stand, take the bottom liquid, spin Dry diethyl ether to get Keggin type H 3 PW 12 o 40 . Weigh 5mmolH 3 PW 12 o 40 In a 25mL round bottom flask, add 10mL of distilled water to dissolve it, slowly add 5mmol of 1-allylimidazole dropwise while stirring, react at 25°C for 48h, filter, wash the product with distilled water, and dry it under vacuum at 60°C overnight to obtain Keggin type 1- Allyl imidazolium phosphotungstic salt.

[0036] 10gNa 2 WO 4 2H 2 Dissolve O in 35mL of water, heat to boiling, slowly add 15mL of concentrated phosphoric acid, react for 8h, cool to room temperature, add 10gKCl, react for ...

Embodiment 3

[0043] Embodiment 3 (degradation reaction)

[0044] (Example 3.1) Add 1.0 g of lignin, 0.05 mmol of Cat.1 catalyst and 10 mL of water into a 25 mL three-necked flask, and react at 120° C. for 6 h. Cool to room temperature, centrifuge, precipitate the catalyst, adjust the pH of the reaction solution to 2, centrifuge, precipitate, dry and weigh, and calculate the degradation rate. The supernatant was extracted with ethyl acetate. The ethyl acetate was passed through a 0.22 μm membrane filter, and the filtrate was qualitatively analyzed by GC-MS.

[0045] (Example 3.2) Add 1.0 g of lignin, 0.05 mmol of Cat.1 catalyst and 10 mL of water into a 25 mL three-neck flask, and react for 7 h at normal pressure and temperature of 90° C. Cool to room temperature, centrifuge, precipitate the catalyst, adjust the pH of the reaction solution to 2, centrifuge, precipitate, dry and weigh, and calculate the degradation rate. The supernatant was extracted with ethyl acetate. The ethyl acetate...

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Abstract

The invention belongs to the field of lignin recycling, and particularly relates to a method for degrading lignin in papermaking black liquor. The method includes steps of (1), extracting the lignin in the papermaking black liquor; (2), adding the lignin extracted at the step (1), a catalyst and aqueous solution into a reaction device according to appropriate proportions and carrying out degradation reaction. The catalyst is imidazole phosphotungstate. The method has the advantages that the imidazole phosphotungstate is used as the catalyst for carrying out the degradation reaction on the lignin extracted from the papermaking black liquor, high-temperature, high-pressure and strongly alkaline environments can be omitted in the integral degradation reaction, the high degradation rate stillcan be guaranteed under mild degradation reaction conditions, the method has low requirements on equipment and is favorable for industrially treating the papermaking black liquor on a large scale, andenergy consumption can be reduced to a great extent; the imidazole phosphotungstate which is the catalyst is non-volatile, has a low melting point, is provided with organic-inorganic hybrid structures and is soluble, and accordingly the catalyst is high in efficiency, easy to recycle and good in reusability.

Description

technical field [0001] The invention belongs to the field of lignin resource utilization, and in particular relates to a method for degrading lignin in papermaking black liquor. Background technique [0002] With the continuous depletion of fossil energy, people's demand for sustainable energy is becoming more and more urgent. Biomass, as the fourth largest energy after coal, oil, and natural gas, has received widespread attention. Biomass is mainly divided into cellulose, hemicellulose, and lignin, among which lignin is a natural polymer biomass second only to cellulose in nature, accounting for 15%-30% of plant mass. So far, more than 80% of lignin has not been utilized due to the complexity of lignin structure and the diversity of bonds, and it is still directly discharged into rivers as waste from papermaking and pulping, causing serious environmental pollution. Therefore, the efficient utilization of lignin can not only solve the problem of environmental pollution, bu...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): D21C11/00
CPCD21C11/00
Inventor 喻宁亚肖佳
Owner HUNAN NORMAL UNIVERSITY
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