Dissolving pulp prehydrolysis solution autocatalysis furfuraldehyde preparation method and recycling method for acetic acid in prehydrolysis solution waste water and furfuraldehyde waste water

A technology of pre-hydrolyzed solution and dissolving pulp, which is applied in chemical instruments and methods, preparation of oxygen-containing compounds, preparation of organic compounds, etc. It can solve problems such as poor flexibility of production operations, deposition of dissolved organic matter, long natural degradation time of lignin, etc. , to achieve the effect of reducing coking and humus formation, avoiding resin reaction, and facilitating subsequent cleaning

Inactive Publication Date: 2013-01-09
TIANJIN UNIV OF SCI & TECH
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AI Technical Summary

Problems solved by technology

[0008] Although the theoretical value of the furfural yield of the above-mentioned 1, 2 invention methods is relatively high, the 1, 2 invention methods have the following disadvantages: 1) hydrolysis of the dissolving pulp The liquid comes from the continuous hydrolysis process. Continuous hydrolysis and cooking will easily lead to the continuous deposition of dissolved organic matter, which will have a great impact on equipment and production.
The production operation of this method is less flexible, and the equipment is complicated. Any piece of equipment shut down for maintenance will affect the operation of the entire system; 2) In the process of dissolving slurry hydrolyzate treatment, 20-100g / L acetic acid needs to be added as a catalyst for dehydration reaction. Increased production costs, and this concentration of acetic acid is corrosive to equipment, and the discharge of acid-containing wastewater also pollutes the environment; 3) The pre-hydrolyzate of dissolving pulp contains a certain amount of lignin in addition to pentosan
When the pre-hydrolyzate is used to prepare furfural, lignin may increase side reactions during the reaction process, reduce the generation of furfural, and cause fouling, which is not conducive to equipment cleaning
And because lignin naturally degrades for a long time, direct discharge will have adverse effects on the environment.

Method used

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  • Dissolving pulp prehydrolysis solution autocatalysis furfuraldehyde preparation method and recycling method for acetic acid in prehydrolysis solution waste water and furfuraldehyde waste water

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0077] See figure 1 , One of the methods for preparing furfural by autocatalytic reaction of dissolving pulp prehydrolyzate A, 300mL of dissolving pulp prehydrolyzate A is placed in a high-pressure reactor, without adding any other sulfuric acid, hydrochloric acid or acetic acid catalysts for intermittent autocatalytic reaction, the reaction temperature is 150 ℃-220 ℃, the reaction temperature of this example is designed to be 170 ℃, the pressure is 0.23MPa-2.32MPa, the pressure of this example is designed to be 0.54MPa-0.57MPa, and the retention time is 20min-160min. The retention time of this example is designed to be 100min. During the process, the polysaccharide is hydrolyzed into pentose, and the pentose is dehydrated and cyclized. After the reaction is completed, the content of total sugar and five-carbon sugar in the receiving solution is measured by ion chromatography, the conversion rate of total sugar and five-carbon sugar is calculated, and the acetic acid is determ...

Embodiment 2

[0082] See figure 1 , The second method of preparing furfural by autocatalytic reaction of dissolving pulp prehydrolyzate A is to put 300mL of hardwood kraft dissolving pulp prehydrolyzate A in a high-pressure reactor for semi-batch autocatalytic reaction, stirring in an automatic mixer at about 80 r / min Start heating at a high speed, and when the temperature of the reaction system reaches 180°C, open the gas phase discharge valve to discharge aldehyde vapor, condense and collect the aldehyde-water mixture, close the gas phase discharge valve after the reaction, turn off the power to cool down, and use ion chromatography to measure the total sugar and Five-carbon sugar content, calculate total sugar, five-carbon sugar conversion rate, adopt nuclear magnetic resonance to measure the concentration of acetic acid and furfural, and the measurement results are shown in Table 2:

[0083] Table 2

[0084] Concentration of furfural in aldehyde water (g / L) Furfural sele...

Embodiment 3

[0087] See figure 1 , Dissolving pulp prehydrolyzate A self-catalyzed reaction to prepare furfural method three, 300mL

[0088] The prehydrolyzate A of hardwood kraft dissolving pulp is placed in a high-pressure reactor, and an equal volume of methyl isobutyl ketone is added as an extractant in a two-phase system. The reaction temperature is 170°C, the pressure is 0.54-0.57MPa, and the retention time 100min to carry out batch reaction, after the reaction is completed, separate the aqueous phase and the organic phase, and measure the two phases respectively, adopt ion chromatography to measure the content of total sugar and five-carbon sugar in the receiving liquid, calculate the conversion rate of total sugar and five-carbon sugar, and use The concentration of acetic acid and furfural was measured by nuclear magnetic resonance, and the measurement results are shown in Table 3:

[0089] table 3

[0090] Concentration of furfural in liquid phase after reaction (g / L)...

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Abstract

The invention discloses a dissolving pulp prehydrolysis solution autocatalysis furfuraldehyde preparation method and a recycling method for acetic acid in prehydrolysis solution waste water and furfuraldehyde waste water after prehydrolysis solution autocatalysis furfuraldehyde preparation. The dissolving pulp prehydrolysis solution autocatalysis furfuraldehyde preparation method includes that dissolving pulp prehydrolysis solution for preparing furfuraldehyde comprises dissolving pulp prehydrolysis solution A, dissolving pulp prehydrolysis solution B from which lignin is eliminated, dissolving pulp prehydrolysis solution C which is evaporated and concentrated and dissolving pulp prehydrolysis solution D which is subjected to membrane filtration and concentration; and the prehydrolysis solutions are placed in high-pressure reactors respectively, catalysts such as sulfuric acid, hydrochloric acid or acetic acid is not required to be added for autocatalysis reaction, during the reaction, pentosan is hydrolyzed into pentose, and the pentose is dehydrated and cyclized to obtain the furfuraldehyde. The acetic acid in the prehydrolysis solution waste water and the furfuraldehyde waste water after prehydrolysis solution autocatalysis furfuraldehyde preparation is recycled through a trioctylamine / n-caprylic alcohol mixture or resin. The methods are practical and operable, and the preparation method is an environmental-friendly preparation method which can turn waste into wealth.

Description

technical field [0001] The invention relates to a method for preparing furfural by self-catalysis of pre-hydrolyzed solution of dissolving pulp, and a method for recovering acetic acid from furfural wastewater after pre-hydrolyzed solution autocatalyzedly prepares furfural from pre-hydrolyzed solution wastewater. Background technique [0002] Woody organisms are widely distributed clean and environmentally friendly renewable resources, and the pulp and paper industry is one of the main ways to utilize woody biomass resources. [0003] Dissolving pulp is a kind of chemically refined pulp with high fiber content and relatively low content of hemicellulose, lignin and other components obtained by chemical processing and purification of plants containing cellulose in nature (such as cotton, wood, etc.). The prehydrolyzate produced by the hot water extraction method before pulping by kraft method is rich in hemicellulose and acetic acid, which can be collected and further process...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07D307/50C07C53/08C07C27/02C07C51/47C07C51/48
Inventor 倪永浩刘海棠胡惠仁
Owner TIANJIN UNIV OF SCI & TECH
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