CN102936632B - A method for improving cellulose hydrolysis efficiency - Google Patents

Abstract

The invention relates to a preparation method and application of a cellulose modifier, in particular to a method capable of improving cellulose hydrolysis efficiency. The present invention uses cyanuric chloride as the active component and phenol or p-hydroxybenzenesulfonic acid or 1-amino-8-naphthol-3,6-sodium disulfonate as the functional component to synthesize the fiber of triazine derivatives prime modifier, and its structure was characterized by infrared and mass spectrograms. Then the fiber was modified with the synthesized triazine derivative, and the modified microcrystalline cellulose was hydrolyzed in 8% H ₂ SO ₄ at 130°C for 5 hours. The results showed that when the relative molar content of the modifier ( (based on glucose ring) at 16.67%, the maximum yield of cellulose hydrolyzed into reducing sugar is 23.54%. Through the analysis of wide-angle X-ray diffraction patterns, it is found that the modification changes the crystal structure of microcrystalline cellulose, increases the amorphous area, and crystallizes. The index decreases and the grain size decreases. This method has broad application prospects in cellulose hydrolysis.

Description

A method for improving cellulose hydrolysis efficiency

technical field

The invention relates to a method for improving cellulose hydrolysis efficiency, in particular to a method for improving cellulose hydrolysis efficiency by chemical modification of cellulose.

Background technique

Ethanol (commonly known as alcohol) is an important industrial raw material, which is widely used in the fields of chemical industry, food, beverage industry, military industry, daily chemical industry, medicine and health, etc. Kg). Cellulose is one of the polysaccharide resources with the highest content in nature. The conversion of cellulose into ethanol as biomass energy has attracted much attention in the field of fossil energy replacement research. However, the key to converting cellulose into clean fuel and chemical ethanol is to find effective The pathway hydrolyzes cellulose to soluble fermentable sugars such as glucose. Cellulose is a long-chain molecule in which β-D-glucose residues are linked by 1,4-glycosidic bonds. The long-chain molecule further forms a supramolecular stable structure with highly crystalline regions, which makes cellulose difficult to hydrolyze. .

Scientific research has found that certain pretreatment of cellulose can increase the yield of reducing sugars produced by its hydrolysis. Currently, cellulose pretreatment methods mainly include physical methods (mechanical crushing, steam explosion, supercritical water treatment, etc.), chemical Methods (alkaline treatment, acid treatment, oxidant treatment, etc.), biological methods. However, these methods have two sides. For example, the steam explosion method will produce substances that inhibit enzymatic hydrolysis and fermentation. Alkali treatment can remove part of the lignin and also take away part of the hemicellulose, affecting the yield of total sugar. Moreover, most of the pretreatment methods for cellulose raw materials do not change its chain structure, and have little effect on the crystal structure, resulting in enzyme-catalyzed hydrolysis that can only occur in the amorphous region of cellulose, and the acid catalyst is accessible to the cellulose crystal region. The degree is also very small. Therefore, finding a pretreatment method that significantly improves the accessibility of cellulose is still the focus of current cellulose-ethanol conversion research.

Posa et al reported that the hydrolysis efficiency of carboxymethylcellulose with low degree of substitution is higher than that of cellulose (J.Borsa, I.Tanczos, I.Rusznak.Acid hydrolysis of carboxymethylcellulsoe of low degree of substitution[J]. 1990,268(7):649-657); David, Karst et al. used molecular simulation methods to study the cellulose modified by groups with different volumes, and predicted that the substituents with larger volumes are beneficial to improve the hydrolysis efficiency of cellulose (David T. Karst, Yiqi Yang. Effect of structure of large aromatic molecules grafted onto cellulose on hydrolysis of the glycosidic linkages [J]. Macromolecular Chemistry and Physics, 2007, 208:784-791); The hydrolysis sugar yield of cyanuric chloride-modified cellulose with phenyl-substituted sulfonic acid groups has been significantly increased (Jiang Xue, Tian Xiuzhi, Gu Jian, Huang Dan, Wang Shugen. Application number: 201110154930.9).

Therefore, the present invention uses cyanuric chloride as an active component, and compound phenol, p-hydroxybenzenesulfonic acid, 1-amino-8-naphthol-3,6-sodium disulfonate as a functional component, The modifier is synthesized by the reaction of hydroxyl and cyanuric chloride, and the cellulose is modified, the chain structure of the cellulose is changed through the reaction of the modifier, the crystallinity of the cellulose is reduced, and the hydrolysis efficiency of the cellulose is improved.

Contents of the invention

The purpose of the invention is to overcome the deficiencies in the existing cellulose fuel ethanol preparation technology, and provide a method for improving cellulose hydrolysis efficiency, which is characterized in that it comprises the following steps:

1) Add the active component solution and reducing agent into the reactor equipped with stirring, put the functional component solution in the constant pressure dripping tank and slowly drop it into the reactor for 1~2h, then 0~5 React at ℃ for 1~3h; filter after precipitation, recrystallize with organic solvent, dry the solid in vacuum at 50℃, and the yield of modifier is 60%~80%.

2) Put 2 parts of cellulose, 10-40 parts of solvent, and 4 parts of alkali solution in the reactor, and place the modifier solution with a relative molar percentage (based on glucose ring) of 1/40-1 part in a constant In the pressure funnel, slowly drop the alkali solution into the reactor, and react at 40°C for 3h; after the reaction, the product was suction filtered, and the filter cake was washed with water until the pH was neutral, and dried in a vacuum oven at 50°C for 24h; Put 0.5 parts of modified cellulose in a stirred reactor, add 10 ml of 8% sulfuric acid, hydrolyze at 130°C for 5 hours, and centrifuge to obtain a hydrolyzate.

The molar mass ratio of the active component to the functional component is 1:1-2. .

The active component is cyanuric chloride,

The solvent of the active component solution is dichloromethane or acetone.

The reducing agent is anhydrous sodium sulfite.

The functional component is any one of phenol, p-hydroxybenzenesulfonic acid, 1-amino-8-naphthol-3, 6-sodium disulfonate or a mixture of more than one in any proportion.

The solvent of the functional component solution is an aqueous solution of anhydrous sodium carbonate.

The recrystallization solvent is a mixture of tetrahydrofuran and water.

The alkaline solution is 10% sodium hydroxide solution.

The present invention uses hydroxyl-containing compounds phenol, p-hydroxybenzenesulfonic acid, and 1-amino-8-naphthol-3,6-sodium disulfonate as functional components, and only introduces hydroxyl-containing compounds into the active component cyanuric chloride benzene ring and naphthalene ring, synthetic cellulose modifier of triazine derivatives, and then modified cellulose with the synthesized triazine derivatives containing different proportions of monophenoxy and naphthyl epoxy triazine rings, Cellulose is modified by s-triazine groups containing benzene rings and naphthalene rings. Experiments have shown that the yield of reducing sugar after hydrolysis of cellulose modified by triazine derivatives is increased. The maximum rate is 23.54%. By analyzing the wide-angle X-ray diffraction pattern, it is found that the modification changes the crystal structure of microcrystalline cellulose, increases the amorphous area, decreases the crystallization index, and reduces the grain size. By changing the chain structure of cellulose, reducing the crystallinity of cellulose and increasing the conversion rate of cellulose hydrolysis into fermentable sugar, this method has broad application prospects in cellulose hydrolysis.

Instructions attached

Figure 1 Mass Spectrum of Modifier

The infrared spectrum of Fig. 2 modifier

Figure 3 Infrared spectrum of modified cellulose

The X-ray diffraction figure of Fig. 4 modified cellulose, (A) cellulose; (B) ~ (F): embodiment 1 ~ 5

Detailed ways

The present invention mainly comprises three parts:

(1) Synthesis of modifiers containing active components and functional components;

(2) Prepare modified cellulose by reacting modifier with cellulose;

(3) Hydrolysis of modified cellulose with different proportions.

The present invention will be further described below in conjunction with specific examples.

Example 1:

(1) Weigh 4 parts of cyanuric chloride into the reactor, add 40 parts of dichloromethane, and then stir in an ice-water bath; use 30 parts of 2 parts of phenol, 2 parts of anhydrous sodium carbonate and 0.1 part of anhydrous sodium sulfite After the water is dissolved, it is slowly dripped into the above system, and it lasts for 1 hour. Continue to react for 2 hours, stop the reaction, pour it into a separatory funnel, and let it stand for 1 hour. The crude product was obtained from methane, and the crude product was recrystallized from THF-water to obtain a white solid with a yield of 65.5%.

(2) Weigh 2 parts of cellulose into the reactor, add 10 parts of acetone; weigh the relative molar content (based on glucose ring) of 1/40 parts of modifier, and add 30 parts of acetone to dissolve it under stirring, And slowly drop it into the above system; use 10wt% NaOH as a catalyst, react at a temperature of 40°C for 3 hours, the product is filtered by suction and washed with deionized water until neutral, and the obtained solid is dried under reduced pressure for 24 hours;

(3) Put 0.5 parts of modified cellulose in a reactor, add 10 parts of sulfuric acid with a concentration of 8%, hydrolyze at 130°C for 5 hours, and centrifuge to obtain hydrolyzed products to be tested.

Example 2:

(1) Weigh 2 parts of cyanuric chloride into the reactor, add 20 parts of dichloromethane, and then stir in an ice-water bath; use 30 parts of 1 part of phenol, 1 part of anhydrous sodium carbonate and 0.1 part of anhydrous sodium sulfite After the water is dissolved, it is slowly dripped into the above system, and it lasts for 1 hour. Continue to react for 2 hours, stop the reaction, pour it into a separatory funnel, and let it stand for 1 hour. The crude product was obtained from methane, and the crude product was recrystallized from THF-water to obtain a white solid with a yield of 75.5%.

(2) Weigh 2 parts of cellulose in the reactor, add 10 parts of acetone; weigh the relative molar content (based on glucose ring) as 1/20 modifier, add 30 parts of acetone to dissolve it under stirring, and Slowly drop into the above system; use 10wt% NaOH as a catalyst, react at a temperature of 40°C for 3 hours, the product is filtered by suction and washed with deionized water until neutral, and the obtained solid is dried under reduced pressure for 24 hours;

(3) Put 0.5 parts of modified cellulose in a reactor, add 10 parts of sulfuric acid with a concentration of 8%, hydrolyze at 130°C for 5 hours, and centrifuge to obtain hydrolyzed products to be tested.

Example 3:

(1) Weigh 1 part of cyanuric chloride into the reactor, add 10 parts of dichloromethane, and then stir in an ice-water bath; use 30 parts of 1 part of phenol, 1 part of anhydrous sodium carbonate and 0.1 part of anhydrous sodium sulfite After the water is dissolved, it is slowly dripped into the above system, and it lasts for 1 hour. Continue to react for 2 hours, stop the reaction, pour it into a separatory funnel, and let it stand for 1 hour. The crude product was obtained from methane, and the crude product was recrystallized with tetrahydrofuran-water to obtain a white solid with a yield of 60.5%.

(2) Weigh 2 parts of cellulose into the reactor, add 10 parts of acetone; weigh the relative molar content (based on glucose ring) of 1/5 parts of modifier, and add 30 parts of acetone to dissolve it under stirring, And slowly drop it into the above system; use 10wt% NaOH as a catalyst, react at a temperature of 40°C for 3 hours, the product is filtered by suction and washed with deionized water until neutral, and the obtained solid is dried under reduced pressure for 24 hours;

(3) Put 0.5 parts of modified cellulose in a reactor, add 10 parts of sulfuric acid with a concentration of 8%, hydrolyze at 130°C for 5 hours, and centrifuge to obtain hydrolyzed products to be tested.

Example 4:

(1) Weigh 4 parts of cyanuric chloride into the reactor, add 40 parts of acetone, and then stir in an ice-water bath; 2 parts of p-hydroxybenzenesulfonic acid, 2 parts of anhydrous sodium carbonate and 0.1 part of anhydrous sodium sulfite are used After dissolving 30 parts of water, slowly drop into the above system, after 1 hour, continue to react for 2 hours, stop the reaction, pour it into a separatory funnel, and let it stand for 1 hour. After the system is fully layered, separate the lower transparent liquid and evaporate The crude product was obtained from dichloromethane, and the crude product was recrystallized with tetrahydrofuran-water to obtain a white solid with a yield of 65.5%.

(2) Weigh 2 parts of cellulose into the reactor, add 10 mL of acetone; weigh the relative molar content (based on glucose rings) of 1/3 part of modifier, add 30 parts of acetone and stir to dissolve it, and Slowly drop into the above system; use 10wt% NaOH as a catalyst, react at a temperature of 40°C for 3 hours, the product is filtered by suction and washed with deionized water until neutral, and the obtained solid is dried under reduced pressure for 24 hours;

(3) Put 0.5 parts of modified cellulose in a reactor, add 10 parts of sulfuric acid with a concentration of 8%, hydrolyze at 130°C for 5 hours, and centrifuge to obtain hydrolyzed products to be tested.

Example 5:

(1) Weigh 4 parts of cyanuric chloride in the reactor, add 40 parts of dichloromethane, and then stir in an ice-water bath; 2 parts of 1-amino-8-naphthol-3,6-sodium disulfonate Dissolve 2 parts of anhydrous sodium carbonate and 0.1 part of anhydrous sodium sulfite with 30 parts of water and slowly drop into the above system. After 1 hour of dripping, continue to react for 2 hours, stop the reaction, pour it into a separatory funnel, and let it stand for 1 hour. After the system was fully layered, the lower transparent liquid was separated, and dichloromethane was distilled off to obtain a crude product, which was recrystallized with tetrahydrofuran-water to obtain a white solid with a yield of 65.5%.

(2) Weigh 2 parts of cellulose into the reactor, add 10 parts of acetone; weigh the relative molar content (based on glucose ring) as 1/2 part of modifier, and add 30 parts of acetone to dissolve it under stirring, And slowly drop it into the above system; use 10wt% NaOH as a catalyst, react at a temperature of 40°C for 3 hours, the product is filtered by suction and washed with deionized water until neutral, and the obtained solid is dried under reduced pressure for 24 hours;

(3) Put 0.5 parts of modified cellulose in a reactor, add 10 parts of sulfuric acid with a concentration of 8%, hydrolyze at 130°C for 5 hours, and centrifuge to obtain hydrolyzed products to be tested.

Various performances such as the structure of the modified cellulose that the modification method of the present invention obtains and hydrolysis performance can adopt following index to detect:

(1) Reducing sugar content: 3,5-dinitrosalicylic acid colorimetric method (DNS) was used to measure the reducing sugar content in the hydrolyzate. The glucose standard curve measured at 494nm is Y=0.91412X-0.10154 (R ² =0.9985). The calculation method is as follows:

(2) Structural analysis and determination: NICOLET NEXUS 470 infrared spectrometer was used for FTIR analysis, and KBr tablet method was used for sample preparation. The resolution of the spectrometer is 4 cm ^-1 , and the number of scans is 30. The X-ray diffraction analysis of the sample is carried out on the D8Advance type X-ray diffractometer of Germany BrukerAXS company, adopts copper target Cu Kα (λ=0.15406nm), power is 1600W (40kV * 40mA), adopts NaI crystal scintillation counter to measure X - The intensity of the ray, the scanning range is 3°-60°, the scanning speed is 4°/min, and the step size is 0.02°.

计算，其中D为晶粒尺寸；k为Scherrer常数，取k=0.89；λ为X射线波长，对铜靶λ＝0.15406nm；B为特征衍射峰的最大半高宽，以弧度表示；θ为Bragg角，文中计算002面的晶粒尺寸。采用公式CrI=(I₀₀₂-I_am)/I₀₀₂计算产物的结晶指数，式中I₀₀₂为002晶面衍射强度的最大值，I_am指2θ=18.3°处的衍射强度。(3) Calculation of grain size: grain size according to Scherrer formula

Calculation, where D is the grain size; k is the Scherrer constant, take k=0.89; λ is the wavelength of X-rays, λ=0.15406nm for the copper target; B is the maximum full width at half maximum of the characteristic diffraction peak, expressed in radians; θ is Bragg angle, the grain size of the 002 plane is calculated in this paper. The crystallization index of the product was calculated using the formula CrI=(I ₀₀₂ -I _am )/I ₀₀₂ , where I ₀₀₂ is the maximum value of the diffraction intensity of the 002 crystal plane, and I _am refers to the diffraction intensity at 2θ=18.3°.

Table 1 Modified cellulose detection results

Claims (4)

1. A method for improving cellulose hydrolysis efficiency, characterized in that it comprises the following steps: 1) Add the active component solution and reducing agent into the reactor equipped with stirring, put the functional component solution in the constant pressure dripping tank and slowly drop it into the reactor for 1~2 hours, then 0~5 Reaction at ℃ for 1~3h; filter after precipitation, and recrystallize with organic solvent, dry the solid in vacuum at 50℃, the yield of modifier is 60%~80%; 2) Mix 2 parts of cellulose, 10~40 parts of solvent, 4 One part of alkaline solution is placed in the reactor, and the relative molar percentage based on the glucose ring is 1/40 to 1 part of the modifying agent solution is placed in a constant pressure funnel, and the alkaline solution is slowly added dropwise into the reactor, 40 React at ℃ for 3 hours; after the reaction, the product is suction filtered, the filter cake is washed with water until the pH is neutral, and dried in a vacuum oven at 50℃ for 24 hours; 1-0.5 parts of modified cellulose are placed in a reactor equipped with stirring, Add 10ml of sulfuric acid with a concentration of 8%, hydrolyze at 130°C for 5 hours, and centrifuge to obtain a hydrolyzate; the molar mass ratio of the active component to the functional component is 1:1-2; the active component is trimeric Cyanogen chloride; the solvent of the active component solution is dichloromethane or acetone; the reducing agent is anhydrous sodium sulfite; the functional component is phenol, p-hydroxybenzenesulfonic acid, 1-amino-8-naphthol- 3. Any one of 6-sodium disulfonate or a mixture of more than one in any proportion. 2. The method according to claim 1, characterized in that the solvent of the functional component solution is an aqueous solution of anhydrous sodium carbonate. 3. The method according to claim 1, characterized in that the recrystallization solvent is a mixture of THF and water. 4. The method according to claim 1, characterized in that the alkaline solution is 10% sodium hydroxide solution.

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