CN114524882B

CN114524882B - Method for improving hydrolysis rate of carbohydrate polymer in solution containing cupric salt

Info

Publication number: CN114524882B
Application number: CN202011320044.4A
Authority: CN
Inventors: 张宗超; 杨祎文
Original assignee: Dalian Institute of Chemical Physics of CAS
Current assignee: Dalian Institute of Chemical Physics of CAS
Priority date: 2020-11-23
Filing date: 2020-11-23
Publication date: 2023-03-14
Anticipated expiration: 2040-11-23
Also published as: CN114524882A

Abstract

The invention discloses a method for improving the hydrolysis rate of a carbohydrate polymer in a cupric salt-containing solution, belonging to the technical field of biomass high-value conversion and utilization. The method specifically comprises the following steps: before the carbohydrate polymer is subjected to hydrolysis reaction in the solution containing the divalent copper salt, the ketone compound containing ortho-hydroxyl is added into the solution containing the divalent copper salt, so that the hydrolysis rate of the carbohydrate polymer is obviously improved. The invention has the beneficial effects that: the ketone compound containing ortho hydroxyl is used as an auxiliary agent, so that the hydrolysis rate of the carbohydrate polymer catalyzed by the cupric salt is greatly improved.

Description

Method for improving hydrolysis rate of carbohydrate polymer in solution containing cupric salt

Technical Field

The invention belongs to the technical field of biomass high-value conversion and utilization, and particularly relates to hydrolysis of a carbohydrate polymer in a cupric salt-containing solution.

Background

With the continuous development and progress of social economy, stone resources such as coal, petroleum, natural gas and the like are exhausted, and the environment is seriously damaged, so that the utilization of renewable resources is widely concerned by scientific researchers. The carbohydrate polymer is a renewable carbon-containing resource with huge inventory in nature, and mainly comprises cellulose, hemicellulose, chitin, starch, maltodextrin and the like. They are carbohydrate polymers, made up of monosaccharides linked by glycosidic bonds, hydrolysis of which is the basis for the conversion of carbohydrate polymers into fuels and high-value chemicals. Among the carbohydrate polymers, cellulose is the most abundant carbohydrate polymer in nature and the most difficult to convert, and the hydrolytic conversion utilization thereof is more concerned.

The chemical essence of cellulose is long-chain polymer polysaccharide formed by connecting anhydroglucose units by beta-1, 4 glycosidic bonds, and the long-chain polymer forms a compact and stable spatial network through a large number of intramolecular and intermolecular hydrogen bonds, so that the cellulose is very stable and difficult to hydrolyze, and the cellulose needs to be hydrolyzed into monosaccharide micromolecule products such as glucose and the like to be converted into other energy molecules such as ethanol, lactic acid, glutamic acid, glucaric acid, 5-hydroxymethylfurfural (5-HMF), levulinic acid and the like or high-value-added chemicals by utilizing the cellulose.

Copper, as a non-noble metal, is relatively inexpensive and readily available and is widely used as the active group of catalysts in the chemical industryAnd (4) dividing. In the conversion of carbohydrate polymers, supported copper-based catalysts are widely used as oxidation catalysts, hydrogenation catalysts and acidic catalysts. The cupric salt is a weak base salt, the metal center of copper ions is a Lewis acid, and certain Bronsted acid can be generated after the cupric salt is dissolved in water, so that the cupric salt has the potential of catalyzing the hydrolysis of carbohydrate polymers. Matteo Mariani et al (Catalysis Communications,2014, 44, 19-23) reported a range of supported CuO' s ₂ The catalyst is used for converting cellulose, water is used as a reaction solvent, the reaction temperature is 180 ℃, the reaction lasts for 24 hours, the yield of reducible sugar is only 10%, and different carriers have no obvious influence on the catalytic hydrolysis rate of CuO2, but the selectivity of the product can be changed. The copper component alone has low activity in hydrolysis reaction of carbohydrate polymer, and needs to be matched with other acidic catalysts such as other metal salts (appl. Catal. A-Gen.2011,391 (1-2), 436-442), acidic ionic liquids (Science China-Chemistry 2016,59 (5), 564-570), and sulfonated activated carbon (Industrial)&Engineering Chemistry Research 2013,52 (33), 11537-11543), to catalyze the efficient conversion of carbohydrate polymers. Although the methods are mature in technology, the methods have the defects of low utilization rate of cellulose, high energy consumption, serious pollution, high requirement on equipment and the like.

WO2009134631A1 discloses a method for preparing high-value chemicals from carbohydrate polymers, and specifically discloses a method for preparing high-value chemicals by using combination PdCl of two metal salts ₂ /CuCl ₂ The method has the advantages that the high-efficiency conversion of the carbohydrate polymer is catalyzed in the imidazole type ionic liquid, the reaction temperature is 120 ℃, the reaction time is 0.5h, the total yield of hydrolysis products can reach more than 60 percent, and the catalytic activity of the single-component cupric salt is very low. In addition, compared with CuCl ₂ ，PdCl ₂ The cost is high, and the cost can be reduced if the single metal component Cu salt can be used as the catalyst. Therefore, how to improve the activity of catalyzing the hydrolysis of the carbohydrate polymer by the single-component cupric salt through the nonmetal auxiliary agent is a problem to be solved urgently.

Disclosure of Invention

The invention aims to solve the problem of low hydrolysis activity of a carbohydrate polymer catalyzed by a single-component cupric salt, and provides a method for increasing the hydrolysis rate of the carbohydrate polymer in a cupric salt-containing solution by adding a ketone compound containing ortho-hydroxyl. The specific method comprises the following steps:

(a) Dissolving a cupric salt in a solvent at the temperature of between 20 and 150 ℃ to obtain a uniform solution A. The solvent contains a large amount of chloride ions or bromide ions, preferably imidazole salt or quaternary ammonium salt or pyridine salt or quaternary phosphonium salt of the chloride ions or the bromide ions. The cupric salt may be, but is not limited to, cupric chloride, cupric bromide, cupric sulfate, cupric nitrate. The total concentration of the divalent copper salt is from 10 mmol/(kg solvent) to 600 mmol/(kg solvent), preferably from 20 mmol/(kg solvent) to 200 mmol/(kg solvent).

(b) Adding ketone compounds containing ortho hydroxyl into the solution A to obtain a solution B, wherein the mass ratio of carbonyl in the ketone compounds to the bivalent copper salt is 0.1-20, preferably 0.1-15. Wherein the parent structure of the ketone compound containing ortho-hydroxyl is

Wherein R is ₁ = alkyl, hydroxy-substituted alkyl, haloalkyl, R ₂ H, alkyl, hydroxy-substituted alkyl, haloalkyl. The structure of the vicinal hydroxyl group-containing ketone compound may also be a dimer form of the parent structure or a tautomer form thereof (formula 1). The ketone compound containing ortho hydroxyl includes but is not limited to 1, 3-dihydroxyacetone, 1, 3-dihydroxyacetone dimer, 1-hydroxyacetone, 1, 4-dihydroxy-2-butanone, and fructose.

(c) Adding the carbohydrate polymer and water into the solution B, heating for 0.1-10 h at 70-180 ℃ to obtain a hydrolysate, and analyzing the product by liquid chromatography. The carbohydrate polymer can be one of cellulose, cellobiose, starch, dextrin, hemicellulose or their combination. The addition amount of the carbohydrate polymer is 0.1-20 wt% of the mass of the solvent. The addition amount of the water is 0.1-50 wt% of the mass of the solvent. Hydrolysates include, but are not limited to, glucose, mannose, xylose, galactose.

Specific examples of dimeric forms or tautomers of ortho-hydroxyketones of formula 1

The beneficial effects of the invention are: the ketone compound containing ortho hydroxyl is used as an auxiliary agent, so that the hydrolysis rate of the carbohydrate polymer catalyzed by the cupric salt is greatly improved.

Detailed Description

Comparative example 1: (1) 0.0747g of anhydrous copper chloride and 10.0080g of 1-butyl-3-methylimidazolium chloride (BMIMCl) are weighed into a 20mL glass bottle, and dissolved for 3.5h at 120 ℃ and 400rpm, the BMIMCl is used as a solvent, the density of the solvent is about 1g/mL, and the concentration of the copper chloride is 55 mmol/(kg of solvent), which is named as solution A.

(2) Weighing 0.5g of the solution A, weighing 45mg of microcrystalline cellulose, weighing 50 microliter of purified water, adding the solution B, heating and stirring at 120 ℃ and 400rpm for 4 hours, and cooling the reaction bottle by flowing water for 0.5 hour.

(3) The reaction solution was subjected to liquid chromatography analysis, whereby yield of cellobiose was 2.1%, yield of glucose was 8.3%, and yield of mannose was 1%.

Example 1: (1) 0.0747g of anhydrous copper chloride and 10.0080g of 1-butyl-3-methylimidazolium chloride (BMIMCl) are weighed into a 20mL glass bottle, and dissolved for 3.5h at 120 ℃ and 400rpm, the BMIMCl is used as a solvent, the density of the solvent is about 1g/mL, and the concentration of the copper chloride is 55 mmol/(kg of solvent), and the solution is named as solution A.

(2) 0.5g of solution A,1.25mg of 1, 3-dihydroxyacetone were weighed into a 4mL reaction flask to form solution B.

(3) Weighing 45mg of microcrystalline cellulose, weighing 50 microliter of purified water, adding the purified water into the solution B, heating and stirring at 120 ℃ and 400rpm for 4 hours, and cooling the reaction flask by running water for 0.5 hour.

(4) The reaction solution was subjected to liquid chromatography analysis, and the product yield was shown in table 1. The yield of cellobiose obtained was 3.3%, the yield of glucose was 39.2%, the yield of mannose was 7.3%, the yield of 1, 6-anhydroglucose was 2.7%, the yield of 5-hydroxymethylfurfural was 10.3%, and the yield of formic acid was 3.8%.

Example 2: (1) 0.0747g of anhydrous copper chloride and 10.0080g of 1-butyl-3-methylimidazolium chloride (BMIMCl) are weighed into a 20mL glass bottle, and dissolved for 3.5h at 120 ℃ and 400rpm, the BMIMCl is used as a solvent, the density of the solvent is about 1g/mL, and the concentration of the copper chloride is 55 mmol/(kg of solvent), which is named as solution A.

(2) 0.5g of solution A,2.5mg of fructose were weighed into a 4mL reaction flask to form solution B.

(4) The reaction solution was subjected to liquid chromatography analysis, whereby yield of cellobiose was 4.2%, yield of glucose was 35.3%, yield of mannose was 6.2%, yield of 1, 6-anhydroglucose was 3.0%, yield of 5-hydroxymethylfurfural was 12.0%, and yield of formic acid was 3%.

Example 3: (1) 0.0747g of anhydrous copper chloride and 10.0080g of 1-butyl-3-methylimidazolium chloride (BMIMCl) are weighed into a 20mL glass bottle, and dissolved for 3.5h at 120 ℃ and 400rpm, the BMIMCl is used as a solvent, the density of the solvent is about 1g/mL, and the concentration of the copper chloride is 55 mmol/(kg of solvent), so that the solution is named as solution A.

(2) 0.5g of solution A,1.25mg of 1, 3-dihydroxyacetone dimer, was weighed into a 4mL reaction flask to form solution B.

(3) Weighing 45mg of microcrystalline cellulose, weighing 50 microliter of purified water, adding the solution B into the solution, heating and stirring the solution at 120 ℃ and 400rpm for 4 hours, and cooling the reaction bottle by using running water for 0.5 hour.

(4) The reaction solution was subjected to liquid chromatography analysis, whereby the yield of cellobiose, glucose, mannose, 1, 6-anhydroglucose, 5-hydroxymethylfurfural and formic acid was 3.2%, 36.3%, 5.6%, 2.5%, 9.4% and 2.0%, respectively, were obtained.

Example 4: (1) 0.0747g of anhydrous copper chloride and 10.0080g of 1-butyl-3-methylimidazolium chloride (BMIMCl) are weighed into a 20mL glass bottle, and dissolved for 3.5h at 120 ℃ and 400rpm, the BMIMCl is used as a solvent, the density of the solvent is about 1g/mL, and the concentration of the copper chloride is 55 mmol/(kg of solvent), which is named as solution A.

(2) 0.5g of solution A,0.35mg of 1, 3-dihydroxyacetone was weighed into a 4mL reaction flask to form solution B.

(4) The reaction solution was subjected to liquid chromatography analysis, and the yield of cellobiose, glucose, mannose, 1, 6-anhydroglucose, 5-hydroxymethylfurfural, and formic acid was 2.2%, 20.8%, 2.1%, 1.5%, 3.4%, and 1.3%, respectively, were obtained.

Comparative examples 1 to 4 and comparative example 1 it was found that the addition of ketones containing ortho-hydroxyl groups, i.e. 1, 3-dihydroxyacetone, fructose, 1, 3-dihydroxyacetone dimer, to the ionic liquid BMIMCl containing a divalent copper salt significantly increased the glucose yield and deep conversion products of reducible sugars were observed, indicating that the activity of the divalent copper salt for catalyzing the hydrolysis of cellulose was significantly increased.

TABLE 1 product yields of examples 1 to 4 and comparative example 1

Comparative example 2: (1) 0.0980g of anhydrous cupric bromide and 10.0000g of 1-ethyl-3-methylimidazolium bromide (EMIMBr) are weighed into a 20mL glass bottle, dissolved for 3.5h at 120 ℃ and 400rpm, EMIMBr is used as a solvent, the density of the EMIMBr is about 1g/mL, and the cupric bromide concentration is 44 mmol/(kg of solvent), which is named as solution A.

(2) Weighing 0.5g of the solution A, weighing 45mg of microcrystalline cellulose, weighing 50 microliter of purified water, adding the purified water into the solution A, heating and stirring at 120 ℃ and 400rpm for 3 hours, and cooling the reaction bottle by running water for 0.5 hour.

(3) The reaction solution was subjected to liquid chromatography analysis, and the yield of cellobiose, glucose and mannose obtained was 2.3%, 8.2% and 1.3%, respectively.

Example 5: (1) 0.0980g of anhydrous cupric bromide and 10.0000g of 1-ethyl-3-methylimidazolium bromide (EMIMBr) are weighed into a 20mL glass bottle, dissolved for 3.5h at 120 ℃ and 400rpm, EMIMBr is used as a solvent, the density of the EMIMBr is about 1g/mL, and the cupric bromide concentration is 44 mmol/(kg of solvent), which is named as solution A.

(3) Weighing 45mg of microcrystalline cellulose, weighing 50 microliter of purified water, adding the purified water into the solution B, heating and stirring at 120 ℃ and 400rpm for 3 hours, and cooling the reaction flask by running water for 0.5 hour.

(4) The reaction solution was subjected to liquid chromatography analysis, whereby yield of cellobiose, glucose, mannose, 1, 6-anhydroglucose, 5-hydroxymethylfurfural and formic acid was 3.3% and 32.2%, 4.3%,1, 6-anhydroglucose, 8.3%, 3.4%, respectively, were obtained.

Comparing example 5 with comparative example 2, it can be seen that the addition of the o-hydroxy group containing ketone, i.e. fructose, in the ionic liquid EMIMBr containing cupric bromide, results in a 4-fold yield of glucose for example 5 over comparative example 2, and deep conversion products of the reducible sugars are observed, indicating CuBr in EMIMBr ₂ The activity of catalyzing cellulose hydrolysis is obviously improved.

Comparative example 3: (1) 0.0887g of anhydrous copper sulfate, 10.0000g of 1-butyl-3-methylimidazolium chloride (BMIMCl) were weighed out in a 20mL glass bottle and dissolved at 120 ℃ and 400rpm for 3.5h, and BMIMCl was used as a solvent with a density of about 1g/mL to prepare a copper sulfate solution with a copper sulfate concentration of 55 mmol/(kg of solvent), which was named as solution A.

(2) Weighing 0.5g of the solution A, 50mg of cellobiose, 50 microliter of purified water, adding the solution B, heating and stirring at 120 ℃ and 400rpm for 20min, and cooling the reaction flask for 0.5h by using running water.

(3) The reaction solution was subjected to liquid chromatography analysis to obtain glucose with a yield of 5.3%,

example 6: (1) 0.0887g of anhydrous copper sulfate and 10.0080g of 1-butyl-3-methylimidazolium chloride (BMIMCl) are weighed into a 20mL glass bottle, and dissolved for 3.5h at 120 ℃ and 400rpm, and the BMIMCl is used as a solvent with the density of 55 mmol/(kg of solvent) of copper sulfate, so that the solution is named as solution A.

(3) Weighing 50mg of cellobiose, weighing 50 microliter of purified water, adding the purified water into the solution B, heating and stirring at 120 ℃ and 400rpm for 20min, and cooling the reaction flask by using running water for 0.5h.

(4) The reaction solution was subjected to liquid chromatography analysis, and the yield of the product was shown in Table 1. The yield of glucose obtained was 53.2%, the yield of mannose was 4.3%, the yield of 1, 6-anhydroglucose was 1.2%, the yield of 5-hydroxymethylfurfural was 6.3%, and the yield of formic acid was 1.8%.

Comparing example 6 with control 3, it can be seen that the addition of the ketone containing the ortho-hydroxyl group, i.e. 1, 3-dihydroxyacetone, in the ionic liquid BMIMCl containing copper sulfate resulted in a 10-fold yield of glucose for example 6 over the control, and deep conversion products of the reducible sugars were observed, indicating a significant increase in the activity of copper sulfate to catalyze the hydrolysis of cellulose in BMIMCl.

Claims

1. A process for increasing the rate of hydrolysis of a carbohydrate polymer in a solution containing a cupric salt,

the method comprises the following specific steps:

a) Dissolving a cupric salt in a solvent at the temperature of 20-150 ℃ to obtain a uniform solution A;

b) Adding one or more of ketone compounds containing ortho hydroxyl groups and/or dimers and/or tautomers thereof into the solution A to obtain a solution B, wherein the ratio of the quantity of carbonyl groups in the ketone compounds to the quantity of bivalent copper substances is 0.1-20;

the parent structure of the ketone compound containing ortho-hydroxyl is

Wherein R is ₁ Alkyl of C1-C30, alkyl of C1-C30 substituted by hydroxyl, and halogenated alkyl of C1-C30; r ₂ H, C1-C30 alkyl, hydroxyl-substituted C1-C30 alkyl, C1-C30 haloalkyl; halogen is one or more of F, cl, br and I;

c) Adding the carbohydrate polymer and water into the solution B, and heating at 70-180 ℃ for 0.1h-10h to obtain a hydrolysate.

2. The method of claim 1, wherein: the ketone compound containing ortho hydroxyl in the step (b) comprises one or more than two of 1, 3-dihydroxyacetone, 1, 3-dihydroxyacetone dimer, 1-hydroxyacetone and 1, 4-dihydroxy-2-butanone.

3. The method of claim 1, wherein: the ratio of the amount of the carbonyl to the amount of the divalent copper in the ketone compound containing ortho-hydroxyl in the step (b) is 0.1 to 15.

4. The method of claim 1, wherein: the total concentration of the divalent copper in the step (a) is 10 mmol/(kg solvent) to 600 mmol/(kg solvent).

5. The method of claim 1, wherein: the carbohydrate polymer is one or the combination of more than two of cellulose, cellobiose, starch, dextrin and hemicellulose.

6. The method of claim 1, wherein: the solvent of step (a) contains a large amount of chloride ions and/or bromide ions.

7. The method of claim 1, wherein: the adding amount of the carbohydrate polymer in the step (c) is 0.1-20 wt% of the mass of the solvent.

8. The method according to claim 1 or 7, characterized in that: the adding amount of the water in the step (c) is 0.1-50 wt% of the mass of the solvent.

9. The method of claim 1, wherein: the hydrolysate is glucose, mannose, xylose, and galactose.

10. The method of claim 4, wherein: the total concentration of the divalent copper in the step (a) is 20 mmol/(kg solvent) to 200 mmol/(kg solvent).

11. The method of claim 6, wherein: the solvent in the step (a) is one or more than two of imidazolium salt, quaternary ammonium salt, quaternary phosphonium salt or pyridinium of chloride ions and/or bromide ions.

12. The method of claim 11, wherein:

the imidazolium salt is an imidazolium salt with substituted alkyl on N of an imidazole ring, the alkyl is C1-C10 alkyl, the alkyl connected with N of a quaternary ammonium group on the quaternary ammonium salt is C1-C10 alkyl, the alkyl connected with P of a quaternary phosphorus group on the quaternary phosphorus salt is C1-C10 alkyl, and the alkyl connected with N of a pyridine ring on the pyridine salt is C1-C10 alkyl.

13. The method of claim 7, wherein: the adding amount of the carbohydrate polymer in the step (c) is 1-10 wt% of the mass of the solvent.

14. The method of claim 8, wherein: the adding amount of water in the step (c) is 0.5-20 wt% of the mass of the solvent.