Method for preparing styrene and 2-acrylamide-2-sodium methylpropanesulfonate copolymer and application of styrene and 2-acrylamide-2-sodium methylpropanesulfonate copolymer
By preparing ST-co-AMPS copolymer as an auxiliary agent, the problem of low enzymatic hydrolysis efficiency of lignocellulose was solved, efficient enzymatic hydrolysis and cost reduction were achieved, and the competitiveness of biomass energy was improved.
Patent Information
- Application Number
- CN202510896879.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-30
- Publication Date
- 2025-09-26
AI Technical Summary
In the existing technology, the enzymatic hydrolysis efficiency of lignocellulose is low, the amount of additives used is large and the cost is high. It is necessary to develop new additives to improve the enzymatic hydrolysis efficiency and reduce the cost.
Styrene and sodium 2-acrylamide-2-methylpropanesulfonate copolymer (ST-co-AMPS) was prepared as a lignocellulose enzymatic hydrolysis aid, which improves the enzymatic hydrolysis efficiency by hindering lignin and protecting cellulase.
The enzymatic hydrolysis efficiency of lignocellulose was increased by 22.5%-37.8%, the amount of additives used was reduced, the enzymatic hydrolysis cost was lowered, and the competitiveness of biomass energy was improved.
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Abstract
Description
Technical Field
[0001] The invention relates to the field of lignocellulose enzymatic hydrolysis, and in particular to a method for using a copolymer of styrene and sodium 2-acrylamide-2-methylpropanesulfonate as a cellulose enzymatic hydrolysis aid. Background Art
[0002] With the continuous increase in global energy consumption and the increasing depletion of fossil energy, the search for renewable, clean energy has become an inevitable trend. Lignocellulose, a natural high-molecular-weight organic complex primarily composed of cellulose, hemicellulose, and lignin, is inexpensive, widely available, and biodegradable, making it an ideal raw material for producing third-generation fuel ethanol. However, the enzymatic hydrolysis efficiency of lignocellulose is low, and lignin severely ineffectively adsorbs cellulase, resulting in high enzymatic hydrolysis costs and directly hindering the industrialization of cellulosic ethanol.
[0003] In order to improve the efficiency of enzymatic hydrolysis of lignocellulose, researchers have mainly focused on two aspects: first, to increase the removal of lignin during the pretreatment process to increase the accessibility of cellulase to cellulose; second, to develop new technologies to reduce the ineffective adsorption between cellulase and lignin. For example, by adding non-catalytic proteins and competitive adsorption to occupy the adsorption sites of lignin, the binding of enzymes to lignin is reduced; by adding surfactants, the hydrophilic groups of the surfactants bind to water, and the hydrophobic groups bind to the hydrophobic regions of lignin or enzymes, destroying the direct adsorption of the two. These additives only alleviate the non-productive adsorption between the substrate lignin and the cellulase by hindering lignin or protecting the cellulase (single effect). Although they can alleviate the problem of non-productive adsorption during the hydrolysis of lignocellulose, the effect is limited.
[0004] Furthermore, non-catalytic proteins present challenges such as high cost, insufficient stability, and difficulty in subsequent separation. Surfactants also pose issues such as foaming and environmental pollution. Therefore, there is an urgent need to develop new technologies that can effectively improve the efficiency of lignocellulose enzymatic hydrolysis while reducing the amount of additives used and the cost of enzymatic hydrolysis. Summary of the Invention
[0005] Technical problem: The technical problem to be solved by the present invention is: to provide a method for preparing a copolymer of styrene and sodium 2-acrylamide-2-methylpropane sulfonate and its application in enzymatic hydrolysis of lignocellulose. In order to reduce the amount of auxiliary agents used in enzymatic hydrolysis of lignin and improve the efficiency of enzymatic hydrolysis of lignocellulose, the present invention first copolymerizes styrene and sodium 2-acrylamide-2-methylpropane sulfonate to prepare a ST-co-AMPS copolymer, and then uses the ST-co-AMPS copolymer as an auxiliary agent for enzymatic hydrolysis of lignocellulose. By the dual effects of hindering lignin and protecting cellulase, the efficiency of enzymatic hydrolysis of lignocellulose is improved, the amount of auxiliary agents used in the enzymatic hydrolysis process is reduced, and the cost of enzymatic hydrolysis is reduced, production efficiency is improved, and the competitiveness of biomass energy is improved.
[0006] Technical solution: To solve the above technical problems, the technical solution adopted by the present invention is: a method for preparing a copolymer of styrene and 2-acrylamide-2-methylpropanesulfonate sodium, comprising:
[0007] S1: Styrene (ST) and sodium 2-acrylamide-2-methylpropanesulfonate (AMPS) were mixed in a certain proportion and added to a water / isopropanol mixture (mixing ratio of 4:1-7:3) for dissolution;
[0008] S2: Add chain transfer agent to S1, stir evenly, introduce nitrogen to remove oxygen, and heat to 60-90°C;
[0009] S3: Slowly add the initiator dropwise to S2, seal the reaction vessel, and react for 3-8 hours. After the reaction is complete, remove impurities and dry to obtain the ST-co-AMPS copolymer.
[0010] In step S1, the monomer molar ratio of styrene (ST) to sodium 2-acrylamide-2-methylpropanesulfonate (AMPS) is 1:1-3:1.
[0011] In step S2, the amount of the chain transfer agent used accounts for 0.4%-0.8% of the total monomer mass, and the chain transfer agent is one or more of isopropyl alcohol, dodecyl mercaptan, and sodium methyl propylene sulfonate.
[0012] In step S3, the amount of initiator used accounts for 4%-18% of the total monomer mass. The initiator is one or more of potassium persulfate (KPS), ammonium persulfate (APS), and sodium persulfate aqueous solution.
[0013] The present invention also provides a method for improving the efficiency of enzymatic hydrolysis by using a copolymer of styrene and sodium 2-acrylamide-2-methylpropanesulfonate as an enzymatic hydrolysis aid, comprising the following steps:
[0014] S4: A certain amount of lignocellulose was added to a 0.05 M acetic acid-sodium acetate buffer solution to obtain a 2% (w / v) slurry, and the ST-co-AMPS copolymer prepared in steps S1-S3 and 10 FPU / g-glucan cellulase were added. The enzymatic hydrolysis was carried out at 50°C and pH = 4.8 / 5.5 for 72 hours to obtain a carbohydrate compound hydrolyzate.
[0015] The lignocellulose in step S4 is the solid residue of pre-treated poplar, corn cob and sugarcane.
[0016] In step S4, the mass ratio of the ST-co-AMPS copolymer to the substrate is 0.01 to 0.15 g / g.
[0017] Beneficial effects: Compared with the prior art, the present invention has the following beneficial effects: The present invention proposes for the first time a method for preparing an ST-co-AMPS copolymer by polymerizing monomers styrene and 2-acrylamide-2-methylpropanesulfonic acid, and prepares an ST-co-AMPS copolymer with a weight-average molecular weight distribution of 5,230-36,029 g / mol and a hydrophobicity distribution of 11.1% to 31.5%.
[0018] The ST-co-AMPS copolymer prepared by the method described herein is used as an enzymatic hydrolysis aid, which can increase the efficiency of cellulose saccharification and enzymatic hydrolysis by 22.5%-37.8%. The ST-co-AMPS copolymer has the dual effects of protecting cellulase and blocking lignin, making it a promising agent for promoting the enzymatic hydrolysis and saccharification of lignocellulose. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Figure 1 (a) FTIR spectrum and (b) representative images of ST-co-AMPS copolymers 1 HNMR spectrum (in SA-XY, SA represents ST-co-AMPS, X represents the amount of initiator, and Y represents hydrophobicity).
[0020] Figure 2 This is the preparation route of the ST-co-AMPS copolymer in the examples. DETAILED DESCRIPTION
[0021] For a better understanding of the present invention, the present invention is further described below in conjunction with the accompanying drawings and examples, but the embodiments of the present invention are not limited thereto. The reagents used in the following examples can be purchased from the market or made in-house. Styrene (ST), sodium persulfate (Na2S2O8), sodium 2-acrylamide-2-methylpropanesulfonate (AMPS) and sodium methyl propenesulfonate (SMAS) were purchased from Aladdin Company (Shanghai, China). ST was used after purification. Cellulase CTec3 was provided by Aladdin (Shanghai, China), and its filter paper enzyme activity was 137 FPU / mL.
[0022] Example 1
[0023] 4.76g of styrene and 5.24g of sodium 2-acrylamide-2-methylpropanesulfonate were weighed and added to 50mL of a water / isopropanol mixture. 0.06g of sodium methylpropenesulfonate (a chain transfer agent) was then added to the solution, stirred evenly, and nitrogen was passed through for 20 minutes to eliminate oxygen. The temperature was then raised to 80°C. 5mL of an aqueous sodium persulfate solution (0.8g) was slowly added dropwise. The reaction vessel was sealed and reacted at this temperature for 6 hours. After the reaction was completed, the reaction liquid was transferred to a separatory funnel and oil-soluble impurities were removed with n-hexane. The recovered reaction liquid was then dialyzed against deionized water (MWCO = 1000Da) to remove water-soluble impurities. After drying, the ST-co-AMPS sample was obtained. The hydrophobicity and weight-average molecular weight of the ST-co-AMPS sample are shown in Table 1.
[0024] Example 2
[0025] 2.56g of styrene and 6.88g of sodium 2-acrylamide-2-methylpropanesulfonate were weighed and added to 50mL of a water / isopropanol mixture. 0.06g of sodium methylpropenesulfonate (a chain transfer agent) was then added to the solution, stirred evenly, and nitrogen was passed through for 20 minutes to eliminate oxygen. The temperature was then raised to 80°C. 5mL of an aqueous sodium persulfate solution (0.8g) was slowly added dropwise. The reaction vessel was sealed and allowed to react at this temperature for 6 hours. After the reaction was completed, the reaction liquid was transferred to a separatory funnel and oil-soluble impurities were removed with n-hexane. The recovered reaction liquid was then dialyzed against deionized water (MWCO = 1000Da) to remove water-soluble impurities. After drying, the ST-co-AMPS sample was obtained. The hydrophobicity and weight-average molecular weight of the ST-co-AMPS sample are shown in Table 1.
[0026] Example 3
[0027] 4.76g of styrene and 5.24g of sodium 2-acrylamido-2-methylpropanesulfonate were weighed and added to a 50mL water / isopropanol mixture. 0.06g of isopropanol (chain transfer agent) was then added to the solution, stirred evenly, and nitrogen was passed through for 20 minutes to remove oxygen. The temperature was then raised to 80°C. 5mL of an aqueous solution of potassium persulfate (1.2g) was slowly added dropwise. The reaction vessel was sealed and allowed to react at this temperature for 10 hours. After the reaction was completed, the reaction liquid was transferred to a separatory funnel and oil-soluble impurities were removed with n-hexane. The recovered reaction liquid was then dialyzed against deionized water (MWCO = 1000Da) to remove water-soluble impurities. After drying, the ST-co-AMPS sample was obtained. The hydrophobicity and weight-average molecular weight of the ST-co-AMPS sample are shown in Table 1.
[0028] Example 4
[0029] 2.56g of styrene and 6.88g of sodium 2-acrylamido-2-methylpropanesulfonate were weighed and added to 50mL of a water / isopropanol mixture. 0.06g of chain transfer agent dodecanethiol was then added to the solution, stirred evenly, and nitrogen was passed through for 20 minutes to remove oxygen. The temperature was then raised to 90°C. 5mL of an aqueous solution of ammonium persulfate (0.4g) was slowly added dropwise. The reaction vessel was sealed and allowed to react at this temperature for 4 hours. After the reaction was completed, the reaction liquid was transferred to a separatory funnel and oil-soluble impurities were removed with n-hexane. The recovered reaction liquid was then dialyzed against deionized water (MWCO = 1000Da) to remove water-soluble impurities. After drying, the ST-co-AMPS sample was obtained. The hydrophobicity and weight-average molecular weight of the ST-co-AMPS sample are shown in Table 1.
[0030] Example 5
[0031] 2.56g of styrene and 6.88g of sodium 2-acrylamide-2-methylpropanesulfonate were weighed and added to 50mL of a water / isopropanol mixture. 0.06g of sodium methylpropenesulfonate (a chain transfer agent) was then added to the solution, stirred evenly, and nitrogen was passed through for 20 minutes to remove oxygen. The temperature was then raised to 80°C. 5mL of an aqueous sodium persulfate solution (1.2g) was slowly added dropwise. The reaction vessel was sealed and allowed to react at this temperature for 6 hours. After the reaction was completed, the reaction liquid was transferred to a separatory funnel and oil-soluble impurities were removed with n-hexane. The recovered reaction liquid was then dialyzed against deionized water (MWCO = 1000Da) to remove water-soluble impurities. After drying, the ST-co-AMPS sample was obtained. The hydrophobicity and weight-average molecular weight of the ST-co-AMPS sample are shown in Table 1.
[0032] Example 6
[0033] 1.85g of styrene and 8.15g of sodium 2-acrylamide-2-methylpropanesulfonate were weighed and added to a 50mL water / isopropanol mixture. 0.06g of sodium methylpropenesulfonate (a chain transfer agent) was then added to the solution, stirred evenly, and nitrogen was passed through for 20 minutes to remove oxygen. The temperature was then raised to 80°C. 5mL of an aqueous sodium persulfate solution (0.4g) was slowly added dropwise. The reaction vessel was sealed and reacted at this temperature for 6 hours. After the reaction was completed, the reaction liquid was transferred to a separatory funnel and oil-soluble impurities were removed with n-hexane. The recovered reaction liquid was then dialyzed against deionized water (MWCO = 1000Da) to remove water-soluble impurities. After drying, the ST-co-AMPS sample was obtained. The hydrophobicity and weight-average molecular weight of the ST-co-AMPS sample are shown in Table 1.
[0034] The ST-co-AMPS samples prepared in Examples 1-6 were subjected to FTIR spectroscopy and 1 HNMR spectrum analysis, the results are as follows Figure 1 .
[0035] The hydrophobicity distribution of the sample ST-co-AMPS refers to the molar proportion of ST in the copolymer, which is expressed by 1 The areas of peaks a, b, c, and e in the HNMR spectrum were obtained. The figure shows that at the same initiator dosage, as the molar ratio of ST to AMPS decreases, the proportion of ST in the copolymer decreases, reflecting the increase in the hydrophilicity of the copolymer.
[0036] like Figure 1 As shown in (a), the absorption peaks of PS and ST-co-AMPS are compared at 3417 cm -1 The absorption peak at 2800-3000 cm is related to the stretching vibration of OH of water molecules and -NH on AMPS. -1 The absorption bands in this region correspond to the asymmetric and symmetric vibrations of the -CH group. -1 and 1540cm -1 The absorption bands at 1040 cm-1 belong to the vibration of the N-substituted groups, namely amide I and amide II groups. -1 The absorption peak at corresponds to the fluctuation of the S=O group on the AMPS unit. Figure 1 As shown in (b), the peak at approximately 4.8 ppm is the D2O solvent peak, the peaks at 7.0-7.5 ppm are characteristic peaks of hydrogen on the benzene ring (a, b, c), the peaks at 1.0-2.0 ppm are characteristic peaks of hydrogen from the methyl and methylene groups on the aliphatic chain (d, g, h), and the peaks at 2.15 ppm are characteristic peaks of hydrogen from the methine group on the aliphatic chain (f, i). Due to the influence of the sulfonic acid group, the characteristic peak of hydrogen at position e shifts downfield to appear at a chemical shift of 3.4 ppm. These changes in characteristic peaks indicate that ST and AMPS successfully participated in the copolymerization reaction.
[0037] The relative molecular weight of the ST-co-AMPS sample was determined by GPC. For samples with good water solubility, the instrument used was operated at 40°C with pure water as the mobile phase at a flow rate of 0.1 mL / min. A polyethylene glycol standard was used as a control. For samples with poor water solubility, the instrument used was operated at 35°C with dimethyl sulfoxide as the mobile phase at a flow rate of 0.4 mL / min. A polystyrene standard was used as a control. The results are shown in Table 1.
[0038] Example 7
[0039] Weigh 2 g of green liquor pretreated poplar wood equivalent to absolute dryness and place it in 100 mL of acetic acid-sodium acetate buffer (0.05 M, pH = 4.8). Add 0.01, 0.025, 0.05, 0.1, and 0.15 g / g of the ST-co-AMPS sample prepared in Example 1, respectively, and finally add 10 FPU / g -Glucan was hydrolyzed by cellulase CTec3 at 50°C and 150 rpm / min for 72 hours, and the glucose yield was measured by high performance liquid chromatography. The results are shown in Table 2. Other experimental conditions remained unchanged, except that the pH of the buffer solution was changed to 5.5 and 0.1 g / g substrate of the ST-co-AMPS sample prepared in Example 1 was added. The glucose yield from enzymatic saccharification is shown in Table 3.
[0040] Example 8
[0041] Weigh 2 g of green liquor pretreated poplar wood equivalent to absolute dryness and place it in 100 mL of acetic acid-sodium acetate buffer (0.05 M, pH = 4.8). Add 0.01, 0.025, 0.05, 0.1, and 0.15 g / g of the ST-co-AMPS sample prepared in Example 2, respectively, and finally add 10 FPU / g - Glucan was hydrolyzed by cellulase CTec3 at 50°C and 150 rpm / min for 72 hours, and the glucose yield was measured by high performance liquid chromatography. The results are shown in Table 2. Other experimental conditions remained unchanged, except that the pH of the buffer solution was changed to 5.5 and 0.1 g / g substrate of the ST-co-AMPS sample prepared in Example 2 was added. The glucose yield from enzymatic saccharification is shown in Table 3.
[0042] Example 9
[0043] Weigh 2 g of green liquor pretreated poplar wood equivalent to absolute dryness and place it in 100 mL of acetic acid-sodium acetate buffer (0.05 M, pH = 4.8). Add 0.01, 0.025, 0.05, 0.1, and 0.15 g / g of the ST-co-AMPS sample prepared in Example 3, respectively, and finally add 10 FPU / g - Glucan was hydrolyzed by cellulase CTec3 at 50°C and 150 rpm / min for 72 hours, and the glucose yield was measured by high performance liquid chromatography. The results are shown in Table 2. Other experimental conditions remained unchanged, except that the pH of the buffer solution was changed to 5.5 and 0.1 g / g substrate of the ST-co-AMPS sample prepared in Example 3 was added. The glucose yield from enzymatic saccharification is shown in Table 3.
[0044] Example 10
[0045] Weigh 2 g of green liquor pretreated poplar wood equivalent to absolute dryness and place it in 100 mL of acetic acid-sodium acetate buffer (0.05 M, pH = 4.8). Add 0.01, 0.025, 0.05, 0.1, 0.15 g / g of ST-co-AMPS sample prepared in any of the examples in Example 4, respectively, and finally add 10 FPU / g -Glucan was hydrolyzed by cellulase CTec3 at 50°C and 150 rpm / min for 72 hours, and the glucose yield was measured by high performance liquid chromatography. The results are shown in Table 2. Other experimental conditions remained unchanged, except that the pH of the buffer solution was changed to 5.5 and 0.1 g / g substrate of the ST-co-AMPS sample prepared in Example 4 was added. The glucose yield from enzymatic saccharification is shown in Table 3.
[0046] Example 11
[0047] Weigh 2 g of green liquor pretreated poplar wood equivalent to absolute dryness and place it in 100 mL of acetic acid-sodium acetate buffer (0.05 M, pH = 4.8). Add 0.01, 0.025, 0.05, 0.1, 0.15 g / g of ST-co-AMPS sample prepared in any of the examples in Example 5, respectively, and finally add 10 FPU / g - Glucan was hydrolyzed by cellulase CTec3 at 50°C and 150 rpm / min for 72 hours, and the glucose yield was measured by high performance liquid chromatography, as shown in Table 2. Other experimental conditions remained unchanged, except that the pH of the buffer solution was changed to 5.5 and 0.0.5 g / g of substrate of the ST-co-AMPS sample prepared in Example 5 was added. The glucose yield from enzymatic saccharification is shown in Table 3.
[0048] Example 12
[0049] 2 g of green liquor-pretreated poplar wood equivalent to absolute dryness was weighed and placed in 100 mL of acetic acid-sodium acetate buffer (0.05 M, pH 4.8). ST-co-AMPS samples prepared in any of the examples in Example 6 were added at 0.01, 0.025, 0.05, 0.1, or 0.15 g / g substrate, respectively. Finally, 10 FPU / g glucan of cellulase CTec3 was added. Enzymatic hydrolysis was performed at 50°C and 150 rpm / min for 72 hours. Glucose yield was determined by HPLC, as shown in Table 2. All other experimental conditions remained unchanged, except that the buffer pH was adjusted to 5.5 and 0.05 g / g substrate of ST-co-AMPS prepared in Example 6 was added. The glucose yield from enzymatic saccharification is shown in Table 3.
[0050] The green liquor pretreated poplar wood can be replaced with corn cobs or solid residues from pretreated sugarcane. Due to limited space, this will not be described in detail.
[0051] The above examples were compared with corresponding blank controls. The blank control group refers to a group in which other enzymatic hydrolysis conditions are the same, but no enzymatic hydrolysis accelerator is added and the enzymatic hydrolysis time is the same.
[0052] Experimental results
[0053] Table 1 Synthesis conditions and structural characteristics of ST-co-AMPS
[0054] Example Hydrophobicity distribution (%) Weight average molecular weight (g / mol) Example 1 31.5 17,476 Example 2 15.3 16,694 Example 3 18.7 23,258 Example 4 15.7 36,029 Example 5 15.3 5,230 Example 6 11.1 22,478
[0055] As shown in Table 1, when the initiator dosage is 4%-12% and the molar ratio of the ST monomer to the AMPS monomer is 3:1-1:2, ST-co-AMPS copolymers with a weight average molecular weight distribution of 5,230-36,029 g / mol and a hydrophobicity distribution of 11.1%-31.5% are obtained.
[0056] Under the same initiator dosage, as the molar ratio of ST to AMPS decreases, the proportion of ST in the copolymer decreases, reflecting the increase in the hydrophilicity of the copolymer.
[0057] Table 2 Enzymatic hydrolysis conversion rate at pH 4.8 with different ST-co-AMPS addition amounts
[0058]
[0059] Table 3 Optimal enzymatic hydrolysis conversion rates of different ST-co-AMPS at pH 5.5
[0060] sample ST-co-AMPS addition amount (g / g) Enzyme hydrolysis conversion rate (%) control group / 43.5 Example 1 0.1 80.7 Example 2 0.1 80.8 Example 3 0.1 90.5 Example 4 0.1 94.0 Example 5 0.05 93.6 Example 6 0.05 88.1
[0061] Tables 1 and 2 show that when the addition amount of ST-co-AMPS is within the range of 0.01-0.15 g / g-substrate, the enzymatic hydrolysis conversion rate reaches 69.4%-83.4% at pH = 4.8, which is 23.8-37.8% higher than that of the blank group. The enzymatic hydrolysis conversion rate of cellulase at pH = 5.5 is slightly lower than that at pH = 4.8. However, after adding ST-co-AMPS, only the enzymatic hydrolysis conversion rate of Example 1 decreases, while the others perform well. In particular, the enzymatic hydrolysis conversion rates of Examples 4-6 at pH = 5.5 increase by 22.8%-24.6% compared to those at pH = 4.8, with the best conversion rate reaching 93.6%-94%.
[0062] The implementation methods of the present invention are not limited to the above-mentioned embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.
Claims
1. A method for preparing a copolymer of styrene and sodium 2-acrylamide-2-methylpropanesulfonate, characterized in that: Here are the steps: S1: Styrene (ST) and sodium 2-acrylamide-2-methylpropanesulfonate (AMPS) were mixed in a certain proportion and added to a water / isopropanol mixture (mixing ratio of 4:1-7:3) for dissolution; S2: Add chain transfer agent to S1, stir evenly, introduce nitrogen to remove oxygen, and heat to 60-90°C; S3: Slowly add the initiator dropwise to S2, seal the reaction vessel, and react for 3-8 hours. After the reaction is completed, remove impurities and dry to obtain the ST-co-AMPS copolymer.
2. The method for preparing a copolymer of styrene and sodium 2-acrylamide-2-methylpropanesulfonate according to claim 1, wherein: In step S1, the monomer molar ratio of styrene (ST) to sodium 2-acrylamide-2-methylpropanesulfonate (AMPS) is 1:1-3:
1.
3. The method for preparing a copolymer of styrene and sodium 2-acrylamide-2-methylpropanesulfonate according to claim 1, wherein: In step S2, the amount of the chain transfer agent used accounts for 0.4% to 0.8% of the total monomer mass, and the chain transfer agent is one or more of isopropyl alcohol, dodecyl mercaptan, and sodium methyl propylene sulfonate.
4. The method for preparing a copolymer of styrene and sodium 2-acrylamide-2-methylpropanesulfonate according to claim 1, wherein: In step S3, the amount of initiator used accounts for 4%-18% of the total monomer mass. The initiator is one or more of potassium persulfate (KPS), ammonium persulfate (APS), and sodium persulfate aqueous solution.
5. A method for improving enzymatic hydrolysis efficiency by using a copolymer of styrene and sodium 2-acrylamide-2-methylpropanesulfonate as an enzyme hydrolysis aid, comprising the following steps: S4: Add lignocellulose to a 0.05 M acetic acid-sodium acetate buffer solution to prepare a 2% (w / v) slurry, add the ST-co-AMPS copolymer prepared by any method of claims 1-5 and 10FPU / g-glucan cellulase, and carry out enzymatic hydrolysis at 50°C and pH = 4.8 / 5.5 for 72 hours to obtain a carbohydrate compound hydrolyzate.
6. The method for preparing a copolymer of styrene and sodium 2-acrylamide-2-methylpropanesulfonate according to claim 5, wherein: The lignocellulose in step S4 is the solid residue of pre-treated poplar, corn cob and sugarcane.
7. The method for preparing a copolymer of styrene and sodium 2-acrylamide-2-methylpropanesulfonate according to claim 5, wherein: In step S4, the mass ratio of the ST-co-AMPS copolymer to the substrate is 0.01-0.15 g / g.