Method for electrochemical deconstruction of straw in aqueous neutral eutectic solvent
By using an electrochemical decomposition method with an aqueous neutral eutectic solvent at ambient temperature and pressure, the problems of high energy consumption and inhibitor generation in straw decomposition under acidic conditions with eutectic solvents were solved, achieving efficient separation and low-cost decomposition of straw components and providing a new approach for the high-value utilization of straw.
Patent Information
- Application Number
- CN202510838110.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-23
- Publication Date
- 2025-10-28
AI Technical Summary
When existing eutectic solvents decompose straw under acidic conditions, the hydrolysis products of cellulose and hemicellulose are further degraded into inhibitors, reducing the utilization rate of fermentable sugars. Moreover, the decomposition process is energy-intensive, costly, and environmentally unfriendly.
The straw was electrochemically decomposed using a water-containing neutral eutectic solvent at room temperature and pressure. The electrocatalytic reaction was carried out using a three-electrode electrolytic cell. After the reaction, solid-liquid separation was performed to obtain a cellulose-rich solid and a hemicellulose-rich hydrolysate. This process avoided the formation of inhibitors and reduced solvent viscosity and cost by adding water.
It achieves efficient separation of straw components with high cellulose retention, high hemicellulose removal, and high lignin recovery. The process is also environmentally friendly, energy-efficient, does not produce inhibitors, and reduces solvent viscosity and cost.
Smart Images
Figure CN120844394A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a method for electrochemically decomposing straw in an aqueous neutral eutectic solvent, belonging to the field of biomass pretreatment technology. Background Technology
[0002] The dwindling fossil fuel reserves and increasing energy demand are forcing society to seek clean and sustainable energy sources. Lignocellulosic biomass, due to its environmentally friendly, inexpensive, abundant, and renewable nature, is considered a promising fossil fuel alternative for producing biofuels, value-added chemicals, and functional materials. Straw, an agricultural waste, is produced in large quantities and is mainly utilized through straw crushing, deep returning to the field, and composting, resulting in low resource utilization. Therefore, the high-value utilization of straw has environmental, social, and economic benefits. Straw is a type of lignocellulosic biomass, and its main components (cellulose, hemicellulose, and lignin) are cross-linked, forming a complex structure and inherent degradation barriers, which limits the high-value conversion of straw. To achieve high-value conversion of straw, its components must first be effectively separated.
[0003] Eutectic solvents, simply prepared from a series of hydrogen bond donors and acceptors, are considered emerging green solvents due to their designability, economy, biocompatibility, and environmental friendliness. Eutectic solvents exhibit good solubility for lignin but poor solubility for cellulose, thus enabling component separation from straw. However, most eutectic solvents used for lignocellulose decomposition are acidic. While they can effectively separate straw components, under acidic conditions, the hydrolysis products of cellulose and hemicellulose (glucose, xylose) further degrade into inhibitors (5-hydroxymethylfurfural, furfural, etc.), reducing the utilization rate of fermentable sugars and inhibiting subsequent biovalue-added transformations. Acidic eutectic solvents also have limitations in terms of environmental friendliness, safety, and equipment compatibility. Furthermore, existing eutectic solvent technologies face challenges such as demanding separation conditions (high temperature, high pressure), high energy consumption, high viscosity, and high cost. In conclusion, developing a method for decomposing straw under mild conditions to obtain cellulose, hemicellulose, and lignin components separately is of great significance for subsequent high-value utilization. Summary of the Invention
[0004] The technical problem to be solved by this invention is to provide a mild method for separating straw components. Specifically, it is to provide a method for decomposing straw using a water-containing neutral eutectic solvent at room temperature and pressure, so that the straw is separated into a solid residue rich in cellulose, a lignin component, and a liquid rich in hemicellulose hydrolysate, with no inhibitors detected in any component. Furthermore, the addition of water reduces the cost and viscosity of the eutectic solvent, increases electron transfer in the electrocatalytic process, and enhances the component separation effect of the eutectic solvent.
[0005] The technical solution of the present invention is: a method for electrochemically decomposing straw in an aqueous neutral eutectic solvent, comprising the following steps: using an aqueous neutral eutectic solvent as the reaction system, the straw is decomposed by an electrocatalytic reaction in an electrolytic cell composed of three electrodes at room temperature and pressure, and a raw material slurry is obtained after the reaction is completed; ethanol is added to the raw material slurry, and solid-liquid separation is performed; the solid component is rich in cellulose; the liquid component is evaporated to remove ethanol and then water is added to obtain a lignin and hemicellulose hydrolysate.
[0006] The neutral eutectic solvent comprises a hydrogen bond acceptor and a hydrogen bond donor, wherein the hydrogen bond acceptor is choline chloride and the hydrogen bond donor is ethylene glycol. The molar ratio of choline chloride to ethylene glycol is 1:2 to 5.
[0007] The mass ratio of the straw to the aqueous neutral eutectic solvent is 1:(10-30).
[0008] The water content in the aqueous neutral eutectic solvent is 0–50 wt%.
[0009] The target voltage for the electrocatalytic reaction is 2–4 V.
[0010] The working electrode and counter electrode for the electrocatalytic reaction are selected from platinum electrodes or graphite electrodes, and the reference electrode is selected from silver / silver chloride electrodes.
[0011] The electrocatalytic reaction time is 8–10 h.
[0012] The beneficial effects of this invention are as follows: This invention utilizes a three-electrode electrolysis device to electrochemically decompose straw in a neutral eutectic solvent system containing water. The neutral eutectic solvent is synthesized from choline chloride and ethylene glycol, featuring simple components, low cost, high biocompatibility, good conductivity, a wide electrochemical window, and high electrochemical stability. As electrolysis proceeds, a liquid containing cellulose, lignin, and hemicellulose-rich hydrolysate with good enzymatic hydrolysis performance is obtained, and no inhibitors (such as 5-hydroxymethylfurfural and furfural) are detected in the hydrolysate. Compared to traditional methods of decomposing straw using eutectic solvents, this method is environmentally friendly, energy-efficient, operates under mild conditions, is simple in reaction, and does not produce inhibitors. Furthermore, the addition of water reduces the viscosity and cost of the eutectic solvent. This provides a more economical and environmentally friendly new approach for the efficient utilization of lignocellulose biomass. Attached Figure Description
[0013] Figure 1 A process route for electrochemical decomposition of straw in an aqueous neutral eutectic solvent;
[0014] Figure 2 For DES with different water contents, graphite electrodes were used at 100 mV / s. -1 The cyclic voltammetry curve is shown below.
[0015] Figure 3For: Detection results of inhibitors in hydrolysate (high performance liquid chromatography) (a) hemicellulose hydrolysate, (b) 5-hydroxymethylfurfural standard, (c) furfural. Detailed Implementation
[0016] The technical solutions adopted by the present invention to achieve the intended purpose will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention and are not intended to limit the present invention in any way. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solutions of the present invention.
[0017] Example 1:
[0018] Choline chloride and ethylene glycol were mixed at a molar ratio of 1:2 and heated and stirred to obtain a neutral eutectic solvent. 30 wt% water was added to the neutral eutectic solvent to obtain an aqueous neutral eutectic solvent. The aqueous neutral eutectic solvent and straw were mixed evenly at a ratio of 1:20 (w / w) and then subjected to an electrocatalytic reaction at room temperature and pressure in an electrolytic cell consisting of three electrodes. The working electrode and counter electrode were selected from platinum electrodes or graphite electrodes, and the reference electrode was selected from silver / silver chloride electrodes. The voltage was 3V, and the reaction time was 10h. After the reaction was completed, a raw material slurry was obtained. Ethanol was added to the raw material slurry, and solid-liquid separation was performed. The solid component was rich in cellulose. After evaporating the liquid component to remove ethanol, water was added to obtain a liquid containing lignin and a hemicellulose-rich hydrolysate. Substituting the relevant data into the following formula, the solid recovery rate was 50.57%, the cellulose retention rate was 91.81%, the hemicellulose removal rate was 98.43%, and the lignin removal rate was 87.69%.
[0019] The calculation methods for the above indicators are as follows:
[0020] Solid recovery rate % = (Mass of solids recovered after pretreatment / Mass of straw before reaction) × 100%
[0021] Component recovery rate % (cellulose, hemicellulose, or lignin) = (mass percentage of each component in the pretreated straw × solid recovery rate) / (mass percentage of the corresponding component in the straw before reaction) × 100%
[0022] Component removal rate % (cellulose, hemicellulose, or lignin) = 100% - corresponding component recovery rate %
[0023] Example 2:
[0024] Choline chloride and ethylene glycol were mixed at a molar ratio of 1:2 and heated and stirred to obtain a neutral eutectic solvent. 10 wt% water was added to the neutral eutectic solvent to obtain an aqueous neutral eutectic solvent. The aqueous neutral eutectic solvent and straw were mixed evenly at a ratio of 1:20 (w / w) and then subjected to an electrocatalytic reaction at room temperature and pressure in an electrolytic cell consisting of three electrodes. The working electrode and counter electrode were selected from platinum electrodes or graphite electrodes, and the reference electrode was selected from silver / silver chloride electrodes. The voltage was 3V, and the reaction time was 10h. After the reaction was completed, a raw material slurry was obtained. Ethanol was added to the raw material slurry, and solid-liquid separation was performed. The solid component was rich in cellulose. After evaporating the liquid component to remove ethanol, water was added to obtain a liquid containing lignin and a hemicellulose-rich hydrolysate. Substituting the relevant data into the following formula, the solid recovery rate was 67.55%, the cellulose retention rate was 60.90%, the hemicellulose removal rate was 95.55%, and the lignin removal rate was 44.99%.
[0025] Example 3:
[0026] Choline chloride and ethylene glycol were mixed at a molar ratio of 1:4 and heated and stirred to obtain a neutral eutectic solvent. The neutral eutectic solvent and straw were then mixed uniformly at a ratio of 1:20 (w / w) and subjected to an electrocatalytic reaction at room temperature and pressure in an electrolytic cell consisting of three electrodes. The working electrode and counter electrode were selected from platinum or graphite electrodes, and the reference electrode was selected from a silver / silver chloride electrode. The voltage was 2V, and the reaction time was 10h. After the reaction was completed, a raw material slurry was obtained. Ethanol was added to the raw material slurry, and solid-liquid separation was performed. The solid component was rich in cellulose. After evaporating the ethanol from the liquid component, water was added to obtain a liquid containing lignin and a hemicellulose-rich hydrolysate. Substituting the relevant data into the following formula, the solid recovery rate was 85.62%, the cellulose retention rate was 85.38%, the hemicellulose removal rate was 12.69%, and the lignin removal rate was 39.35%.
Claims
1. A method for electrochemically deconstructing straw in an aqueous neutral eutectic solvent, characterized in that: Includes the following steps: The straw was decomposed by electrocatalytic reaction in an electrolytic cell composed of three electrodes at room temperature and pressure using a water-containing neutral eutectic solvent as the reaction system. After the reaction was completed, a raw material slurry was obtained. Ethanol was added to the raw material slurry, and solid-liquid separation was performed. The solid component was rich in cellulose. After the liquid component was evaporated to remove ethanol, water was added to obtain a lignin and hemicellulose hydrolysate.
2. The method for electrochemically deconstructing straw in an aqueous neutral eutectic solvent according to claim 1, characterized in that: The neutral eutectic solvent comprises a hydrogen bond acceptor and a hydrogen bond donor, wherein the hydrogen bond acceptor is choline chloride and the hydrogen bond donor is ethylene glycol.
3. The method for electrochemically deconstructing straw in an aqueous neutral eutectic solvent according to claim 1, characterized in that: The mass ratio of the straw to the aqueous neutral eutectic solvent is 1:(10-30).
4. The method for electrochemically deconstructing straw in an aqueous neutral eutectic solvent according to claim 2, characterized in that: The molar ratio of choline chloride to ethylene glycol is 1:2 to 5.
5. The method for electrochemically deconstructing straw in an aqueous neutral eutectic solvent according to claim 1, characterized in that: The water content in the aqueous neutral eutectic solvent is 0–50 wt%.
6. The method for electrochemically deconstructing straw in an aqueous neutral eutectic solvent according to claim 1, characterized in that: The target voltage for the electrocatalytic reaction is 2–4 V.
7. The method for electrochemically deconstructing straw in an aqueous neutral eutectic solvent according to claim 1, characterized in that: The working electrode and counter electrode for the electrocatalytic reaction are selected from platinum electrodes or graphite electrodes, and the reference electrode is selected from silver / silver chloride electrodes.
8. The method for electrochemically deconstructing straw in an aqueous neutral eutectic solvent according to claim 1, characterized in that: The electrocatalytic reaction time is 8–10 h.