Carbon-based fuel combustion ash washing liquid and application thereof in biomass sugar conversion and fermentation process

Abstract

The invention relates to a carbon-based fuel combustion ash washing liquid which is a liquid mixture containing carbon-based fuel combustion ash and / or a carbon-based fuel combustion ash dissolved matter. The invention also provides an application of the carbon-based fuel combustion ash water washing liquid in biomass sugar conversion and process, and the carbon-based fuel combustion ash is used for lignocellulose pretreatment and promotion of enzymolysis and fermentation, so that the waste liquid treatment, enzymolysis and fermentation cost in the biorefinery process of lignocellulose can be reduced; the method has the advantages that the method is simple and convenient to operate, the alkaline carbon-based fuel combustion ash content in the thermoelectric supply link can be treated, the carbon-based fuel combustion ash content in the thermoelectric supply link can be recycled, waste is turned into wealth, and introduction of exogenous organic and inorganic base catalysts and introduction of an enzymolysis buffer agent and fermentation nutritive salt in the traditional biomass fermentation conversion process are avoided. The method has the advantages of low cost, remarkable environmental benefits and the like.

Description

Technical Field

[0001] This invention belongs to the field of lignocellulose resource utilization technology, and relates to a carbon-based fuel combustion ash water washing liquid and its application. Background Technology

[0002] Lignocellulose is a carbon-neutral bioenergy feedstock with vast reserves. It is estimated that the world's annual lignocellulose production is approximately 200 billion tons. The incineration of agricultural waste and its return to the fields causes significant environmental pollution, including greenhouse gas and pollutant emissions, exacerbating the greenhouse effect and soil pollution. Therefore, developing effective technologies to promote the bioutilization of lignocellulose is crucial.

[0003] Pretreatment technologies can effectively decompose lignocellulosic biomass. Cost-effective pretreatment processes must improve sugar formation in the later stages of enzymatic hydrolysis, reduce carbohydrate degradation and the formation of hydrolysis and fermentation inhibitors, while avoiding sugar loss, reducing energy demand, and lowering the production cost of biomass fuels. To further reduce costs, the entire biomass energy production chain needs to be optimized, including biomass pretreatment, enzymatic hydrolysis, fermentation, and separation, to achieve the final yield and commercialization strategy for biofuels. The production of biochemicals from lignocellulosic biomass typically involves pretreatment, hydrolysis, and fermentation. The main goal of pretreatment is to break down the lignin-carbohydrate complex, thereby increasing carbohydrate accessibility to enzymes. Several pretreatment strategies for converting biomass into value-added bioproducts have been explored, including physical (e.g., grinding and milling), physicochemical (e.g., steam explosion (SE) and wet oxidation), chemical (e.g., alkalis, dilute acids, oxidants, and organic solvents), and biological methods. Despite the numerous pretreatment methods available, the most pressing needs remain to improve the efficiency of enzymatic hydrolysis and saccharification of lignocellulose and thus enable large-scale production of biofuels. These needs include reducing the cost of treatment reagents, minimizing energy consumption during operation, simplifying operation methods, and ensuring that released pollutants are non-toxic and harmless.

[0004] In enzymatic hydrolysis, to achieve the optimal pH for cellulose hydrolysis and improve its efficiency, a strong-base, weak-acid salt solution is typically used as a buffer to stabilize the pH of the aqueous phase. Currently, buffers commonly used for lignocellulose hydrolysis are salt solutions of a certain concentration, prepared from citric acid / sodium citrate, with a pH of 4.5-5.5. These salt solutions possess strong stability, and the hydrolysate containing citric acid / sodium citrate is suitable for the fermentation of various biochemicals. Furthermore, after enzymatic hydrolysis using traditional buffered salt systems, the lack of nutrients in the hydrolysate cannot meet the needs of normal fermentation and strain metabolism. Therefore, exogenous nutrients, such as amino acids and inorganic salts, are often required to support normal microbial metabolic production. The addition of exogenous nutrients undoubtedly increases the complexity of cellulose biomass energy fermentation and raises the probability of contamination during the fermentation process. To address this issue, the applicant previously reported an enzymatic hydrolysis buffer system based on phosphate / potassium dihydrogen phosphate. In this system, the phosphorus and potassium sources necessary for acetone-butanol fermentation can be added to the liquid phase before enzymatic hydrolysis begins. After enzymatic hydrolysis, even without the addition of other exogenous nutrients, a high level of ABE solvent metabolism production can be achieved in the hydrolysate without detoxification (Bioresource Technology, 2016, 211, 117-124). However, the addition of phosphate still increases the overall cost.

[0005] The sources of ash from carbon-based fuel combustion include one or more of the following: fly ash, coal combustion residue, biomass pellet combustion, biomass pyrolysis gasification and liquefaction, and bottom ash or fly ash from coal tar combustion. Coal ash primarily consists of oxides and salts of elements such as silicon, aluminum, iron, titanium, calcium, magnesium, sulfur, potassium, and sodium. The main component of biomass combustion ash is potassium carbonate (K₂CO₃), with a relative molecular mass of 138. Potassium is the most abundant element, generally accounting for 6-12%, with over 90% being water-soluble and existing in carbonate form. Phosphorus is the second most abundant element, generally accounting for 1.5-3%. It also contains calcium, magnesium, silicon, sulfur, and trace elements such as iron, manganese, copper, zinc, boron, and molybdenum. Since carbon-based fuel combustion ash is the ash from the combustion of coal or biomass, it contains almost all the mineral elements found in plants and coal. Currently, the utilization of ash from carbon-based fuel combustion is mainly focused on building materials and engineering applications, primarily as an admixture in cement and concrete, in the production of gray bricks and lightweight aggregates, and in civil engineering fields such as road construction, foundation work, and mine backfilling. A small amount of ash is used for resource utilization in areas such as geopolymers, environmental adsorbents, and the recovery of valuable elements. These approaches have alleviated the pressure of ash stockpiling to some extent, but overall, they still suffer from low added value and strong dependence on ash composition and quality, making it difficult to directly enter mature application systems. Furthermore, in the current application and emission of biomass ash, the leachate is acidic to strongly alkaline, which increases soil clumping, sintering, scaling, slagging, and corrosion. Toxic elements also cause serious harm to air, water, and plants, leading to severe environmental problems and health risks. The potential risks of heavy metals and soluble salts in ash limit its application in agriculture and the environment. High-value utilization generally faces bottlenecks such as high cost, complex processes, lack of scale, and imperfect standard systems, hindering the sustainable and efficient utilization of ash.

[0006] Therefore, there is an urgent need to research and develop a method that can both reduce the cost of wastewater treatment in the biorefining process of lignocellulose and enable the recycling of ash from the combustion of alkaline carbon-based fuels in the thermal power supply process. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a carbon-based fuel combustion ash washing liquid that can be used for lignocellulose pretreatment, cellulase hydrolysis and fermentation, in order to overcome the shortcomings of the prior art.

[0008] This invention also provides the application of the above-mentioned carbon-based fuel combustion ash washing liquid in biomass sugar conversion and processes, including lignocellulose pretreatment and enzymatic hydrolysis methods, as well as the production of bio-based chemicals. Utilizing carbon-based fuel combustion ash for lignocellulose pretreatment and promoting enzymatic hydrolysis and fermentation can reduce the costs of waste liquid treatment, enzymatic hydrolysis, and fermentation in the biorefining process of lignocellulose, dispose of alkaline carbon-based fuel combustion ash in the thermal power supply stage, and realize the reuse of carbon-based fuel combustion ash in the thermal power supply stage.

[0009] Therefore, the first aspect of the present invention provides a washing solution of carbon-based fuel combustion ash, which is a liquid mixture containing carbon-based fuel combustion ash and / or carbon-based fuel combustion ash leachate.

[0010] In this invention, the sources of ash from the combustion of carbon-based fuels include one or more of the following: direct field incineration, boiler combustion, biomass pyrolysis gasification and liquefaction processes, and power generation and heat collection devices using shaped biomass pellets; preferably, the sources of ash from the combustion of carbon-based fuels include one or more of the following: fly ash, coal combustion residue, biomass pellet combustion, biomass pyrolysis gasification and liquefaction, and bottom ash or fly ash after coal tar combustion.

[0011] In some embodiments of the present invention, the liquid mixture containing carbon-based fuel combustion ash leachate is a solid-liquid mixture containing insoluble solid particles obtained by mixing carbon-based fuel combustion ash with a liquid phase matrix; preferably, in the liquid mixture containing carbon-based fuel combustion ash leachate, the amount of carbon-based fuel combustion ash dissolved is 0.5% to 50% (mass / volume).

[0012] In some other embodiments of the present invention, the liquid mixture containing carbon-based fuel combustion ash leachate is a supernatant or colloidal solution obtained by mixing carbon-based fuel combustion ash with a liquid matrix, dissolving the soluble components and separating the solids and liquids, and then removing any solid residue.

[0013] Preferably, the pH of the liquid mixture containing ash leachate from the combustion of carbon-based fuels is 6-14.

[0014] In some embodiments of the present invention, the mass ratio of liquid matrix to carbon-based fuel combustion ash is 1:5 to 20:1.

[0015] In this invention, the liquid matrix includes one or more of water, alcohols, esters, ketones, ethers, ionic liquids, organic acids, dilute inorganic acids, furan compounds, and tetrahydrofuran.

[0016] Preferably, the liquid matrix is ​​in a homogeneous phase, a two-phase phase, or a three-phase phase; more preferably, the liquid matrix is ​​in a liquid state at a temperature ≤50℃.

[0017] In some embodiments of the present invention, ultrasonic mixing is used, wherein the mixing temperature is 50-140°C and the mixing time is 5-20 min.

[0018] The second aspect of the present invention provides the application of the carbon-based fuel combustion ash water washing liquid as described in the first aspect of the present invention in the biomass sugar conversion and fermentation process, wherein the biomass sugar conversion and fermentation process includes one or more of lignocellulose pretreatment, lignocellulose enzymatic hydrolysis and bio-based chemical production.

[0019] According to an embodiment of the first aspect of the present invention, the method for pretreating lignocellulose includes:

[0020] Step A: The pretreatment agent is thoroughly mixed with the pulverized lignocellulose to form a solid-liquid mixture, then stirred and reacted to obtain the pretreated crude product;

[0021] Step B involves separating, washing, and drying the solid material from the pretreated crude product to obtain dried lignocellulose pretreated residue.

[0022] The pretreatment agent is either the carbon-based fuel combustion ash washing liquid described in the first aspect of the present invention or a combination of the carbon-based fuel combustion ash washing liquid described in the first aspect of the present invention and one or more of organic bases, inorganic bases, organic acids, inorganic acids, organic solvents and salts.

[0023] According to the present invention, in step A, the mass-to-volume ratio of the lignocellulose to the pretreatment agent is 1:20 to 20:1.

[0024] In some embodiments of the present invention, in step A, the reaction is carried out at 25-300°C, preferably 80-180°C.

[0025] In some embodiments of the present invention, in step A, the reaction time is 0.5-20 h, preferably 0.5-3 h.

[0026] In some specific preferred embodiments of the present invention, the organic base includes one or more of ethylenediamine, ethanolamine, methylamine, urea, and ammonia.

[0027] In some specific preferred embodiments of the present invention, the inorganic base includes one or more of sodium hydroxide, potassium hydroxide, calcium oxide, and calcium hydroxide.

[0028] In some specific preferred embodiments of the present invention, the organic acid includes one or more of formic acid, acetic acid, butyric acid, lactic acid, and benzenesulfonic acid.

[0029] In some specific preferred embodiments of the present invention, the organic solvent includes one or more of methanol, ethanol, ethylene glycol, glycerol, etc.

[0030] In some specific preferred embodiments of the present invention, the inorganic acid includes one or more of hydrochloric acid, phosphoric acid, sulfuric acid, and nitric acid.

[0031] In some specific preferred embodiments of the present invention, the salts include one or more of choline chloride, betaine, triethylammonium sulfate, magnesium chloride, ferric chloride, and calcium chloride.

[0032] According to a second aspect of the present invention, the method for enzymatic hydrolysis of lignocellulose includes: mixing lignocellulose residue with an enzymatic hydrolysis buffer, adding cellulase, stirring evenly, adjusting the pH, and performing enzymatic hydrolysis to obtain an enzymatic hydrolysate based on carbon-based ash water washing buffer salt.

[0033] The enzymatic hydrolysis buffer is the carbon-based fuel combustion ash washing solution described in the first aspect of this invention.

[0034] In some embodiments of the present invention, the pH value of the enzymatic hydrolysis buffer is 4-7, preferably 4-6, more preferably 4.5-5.5, and even more preferably 4.8-5.0.

[0035] In some embodiments of the present invention, the amount of cellulase used is 0.1-80 FPU / g lignocellulose residue; preferably 2-30 FPU / g lignocellulose residue, more preferably 10-25 FPU / g lignocellulose residue, and even more preferably 10-20 FPU / g lignocellulose residue.

[0036] According to the present invention, the lignocellulose residue includes lignocellulose pretreated residue and / or other lignocellulose pretreated residue obtained by the lignocellulose pretreatment method described in the first aspect of the present invention.

[0037] According to an embodiment of a third aspect of the present invention, the method for producing the bio-based chemical comprises: adjusting the pH of a nutrient source mixture to the pH required for fermentation, introducing a fermentation strain for producing the bio-based chemical into the mixture, and performing fermentation culture to produce the bio-based chemical; wherein the nutrient source mixture comprises an enzymatic hydrolysate based on carbon-based ash water washing buffer obtained in the lignocellulose enzymatic hydrolysis method described in the second aspect of the present invention and / or the carbon-based fuel combustion ash water washing liquid described in the first aspect of the present invention.

[0038] In this invention, the nutrient source mixture further comprises a carbon source; preferably, the carbon source comprises glucose and / or xylose.

[0039] This invention discloses a carbon-based fuel combustion ash washing solution, which is a solution containing carbon-based fuel combustion ash and / or containing carbon-based fuel combustion ash leachates. The carbon-based fuel combustion ash washing solution can be used for lignocellulose pretreatment, cellulase hydrolysis, and fermentation.

[0040] The application of carbon-based fuel combustion ash washing liquid in biomass sugar conversion and processes provided by this invention utilizes carbon-based fuel combustion ash for lignocellulose pretreatment, enzymatic hydrolysis, and fermentation. This invention leverages the terminal carbon-based fuel combustion ash from the biorefining process to catalyze the depolymerization of lignocellulose structures, turning waste into treasure. This avoids the introduction of exogenous organic and inorganic alkaline catalysts, enzymatic hydrolysis buffers, and fermentation nutrients in traditional biomass fermentation conversion processes. This method has numerous advantages, including low cost and significant environmental benefits. Attached Figure Description

[0041] The invention will be further described below with reference to the accompanying drawings.

[0042] Figure 1 A schematic diagram of the process for preparing bio-based chemicals by fermentation of lignocellulose. Detailed Implementation

[0043] To facilitate understanding of the present invention, it will be described in detail below with reference to the accompanying drawings and specific embodiments. However, before describing the present invention in detail, it should be understood that the present invention is not limited to the specific embodiments described. It should also be understood that the terminology used herein is for describing specific embodiments only and is not intended to be restrictive.

[0044] Where numerical ranges are provided, it should be understood that every intermediate value between the upper and lower limits of the range and any other specified or intermediate value within the specified range is covered by this invention. The upper and lower limits of these smaller ranges may be independently included in the smaller range and are also covered by this invention, subject to any explicitly excluded limits within the specified range. Where a specified range includes one or two limits, the range excluding any or both of those included limits is also included by this invention.

[0045] Unless otherwise defined, all terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. While any methods and materials similar to or equivalent to those described herein may also be used in the practice or testing of this invention, preferred methods and materials are now described.

[0046] As mentioned earlier, in the fermentation process of cellulose biomass energy, the most urgent needs for improving the efficiency of enzymatic hydrolysis and saccharification of lignocellulose and thus large-scale production of biofuels are to reduce the cost of pretreatment reagents, reduce energy consumption in the operation process, simplify the operation method, and ensure that the released pollutants are non-toxic and harmless. During enzymatic hydrolysis, the addition of exogenous nutrients due to the lack of nutrients in the hydrolysate not only increases the complexity of fermentation of fiber biomass energy but also raises the probability of contamination during fermentation. Although adding phosphates can overcome these problems, it increases the overall cost. Currently, the utilization of ash from carbon-based fuel combustion is mainly for building materials and engineering disposal, which alleviates the pressure of ash stockpiling to some extent, but still suffers from low added value and strong dependence on ash composition and quality, making it difficult to directly enter mature application systems. At the same time, in the current application and emission of biomass ash, the leachate is acidic to strongly alkaline, which increases soil clumping, sintering, scaling, slagging, and corrosion. Meanwhile, toxic elements cause serious harm to air, water, and plants, leading to serious environmental problems and health risks. The potential risks of heavy metals and soluble salts in ash limit its application in agriculture and the environment. High-value utilization generally faces bottlenecks such as high cost, complex processes, lack of scale and imperfect standard systems, which restrict the sustainable and efficient utilization of ash. Therefore, there is an urgent need to research and develop a method that can both reduce the cost of wastewater treatment in the biorefining process of lignocellulose and enable the recycling of ash from the combustion of alkaline carbon-based fuels in the thermal power supply process.

[0047] In view of this, the inventors have conducted extensive and in-depth research on pretreatment technology, enzymatic hydrolysis process, biomass ash, and fermentation process of fiber biomass energy. The inventors discovered that dissolving the soluble components of carbon-based fuel combustion ash in different solvents results in an alkaline solution, making it an ideal alkaline pretreatment catalyst. The ash contains various alkali metal ions, including sodium ions (0.5-2 g / L), potassium ions (5-20 g / L), calcium ions (0.5-5 g / L), and magnesium ions (1-10 mg / L). These different alkali metal ions can attack the ether bonds between lignin and hemicellulose, while simultaneously swelling cellulose and retaining hemicellulose, exhibiting a certain synergistic effect. This process can efficiently degrade lignocellulose and achieve efficient recovery and utilization of cellulose and hemicellulose components.

[0048] Further research by the applicant revealed that dissolving the soluble components of carbon-based fuel combustion ash in different solvents reveals alkalinity, buffering properties, and trace elements, making it an ideal alkaline pretreatment catalyst, enzymatic buffer salt, and fermentation nutrient salt. Different alkali metal ions in the ash can attack the ether bonds between lignin and hemicellulose, while simultaneously swelling cellulose and retaining hemicellulose, with a certain synergistic effect between them. This process can efficiently degrade lignocellulose and achieve efficient recovery and utilization of cellulose and hemicellulose components. Different weakly alkaline salts form a buffer system, and trace metal elements such as calcium, potassium, and magnesium provide nutrients for the fermentation process. This invention is thus derived.

[0049] Based on the above research, the first aspect of the present invention provides a carbon-based fuel combustion ash washing solution, which is a solution containing carbon-based fuel combustion ash and / or containing carbon-based fuel combustion ash leachates.

[0050] In this invention, the sources of ash from the combustion of carbon-based fuels include one or more of the following: direct field incineration, boiler combustion, biomass pyrolysis gasification and liquefaction processes, and power generation and heat collection devices using shaped biomass pellets; specifically, the sources of ash from the combustion of carbon-based fuels include one or more of the following: fly ash, coal combustion residue, biomass pellet combustion, biomass pyrolysis gasification and liquefaction, and bottom ash or fly ash after coal tar combustion.

[0051] In some embodiments of the present invention, the solution containing carbon-based fuel combustion ash leachate is a solid-liquid mixture containing insoluble solid particles obtained by mixing carbon-based fuel combustion ash with a liquid matrix; preferably, in the solution containing carbon-based fuel combustion ash leachate, the amount of carbon-based fuel combustion ash dissolved is 0.5% to 50% (mass / volume).

[0052] In some embodiments of the present invention, the solution containing carbon-based fuel combustion ash leachate is a supernatant or colloidal solution obtained by mixing carbon-based fuel combustion ash with a liquid matrix, dissolving the soluble components and separating the solids and liquids, and then removing any solid residue.

[0053] Preferably, the pH of the solution containing carbon-based fuel combustion ash leachate is 6-14.

[0054] In some embodiments of the present invention, the mass ratio of liquid matrix to carbon-based fuel combustion ash is 1:5 to 20:1.

[0055] In this invention, the liquid matrix includes one or more of water, alcohols, esters, ketones, ethers, ionic liquids, organic acids, dilute inorganic acids, furan compounds, and tetrahydrofuran.

[0056] Preferably, the liquid matrix is ​​in a homogeneous phase, a two-phase phase, or a three-phase phase; more preferably, the liquid matrix is ​​in a liquid state at a temperature ≤50℃.

[0057] In some embodiments of the present invention, ultrasonic mixing is used, wherein the mixing temperature is 50-140°C and the mixing time is 5-20 min.

[0058] The research results show that the carbon-based fuel combustion ash washing liquid provided by the present invention can be used for lignocellulose pretreatment, cellulase hydrolysis, and fermentation.

[0059] The second aspect of the present invention relates to the application of the carbon-based fuel combustion ash water washing liquid as described in the first aspect of the present invention in the biomass sugar conversion and fermentation process, wherein the biomass sugar conversion and fermentation process includes one or more of lignocellulose pretreatment, lignocellulose enzymatic hydrolysis and bio-based chemical production, wherein the lignocellulose pretreatment, lignocellulose enzymatic hydrolysis and bio-based chemical production can be carried out individually or in combination.

[0060] According to an embodiment of the first aspect of the present invention, the method for pretreating lignocellulose includes:

[0061] Step A: The pretreatment agent is thoroughly mixed with the pulverized lignocellulose to form a solid-liquid mixture, then stirred and reacted to obtain the pretreated crude product;

[0062] Step B involves separating, washing, and drying the solid material from the pretreated crude product to obtain dried lignocellulose pretreated residue.

[0063] The pretreatment agent is either the carbon-based fuel combustion ash washing liquid described in the first aspect of the present invention or a combination of the carbon-based fuel combustion ash washing liquid described in the first aspect of the present invention and one or more of organic bases, inorganic bases, organic acids, inorganic acids, organic solvents and salts.

[0064] In some specific preferred embodiments of the present invention, the organic base includes one or more of ethylenediamine, ethanolamine, methylamine, urea, and ammonia.

[0065] In some specific preferred embodiments of the present invention, the inorganic base includes one or more of sodium hydroxide, potassium hydroxide, calcium oxide, and calcium hydroxide.

[0066] In some specific preferred embodiments of the present invention, the organic acid includes one or more of formic acid, acetic acid, butyric acid, lactic acid, and benzenesulfonic acid.

[0067] In some specific preferred embodiments of the present invention, the organic solvent includes one or more of methanol, ethanol, ethylene glycol, glycerol, etc.

[0068] In some specific preferred embodiments of the present invention, the inorganic acid includes one or more of hydrochloric acid, phosphoric acid, sulfuric acid, and nitric acid.

[0069] In some specific preferred embodiments of the present invention, the salts include one or more of choline chloride, betaine, triethylammonium sulfate, magnesium chloride, ferric chloride, and calcium chloride.

[0070] According to the present invention, in step A above, the pretreatment method includes one or more of physical, chemical and biological methods.

[0071] In some specific preferred embodiments of the present invention, for example, in step A above, the pretreatment agent is thoroughly mixed with pulverized lignocellulose to form a solid-liquid mixture, and then stirred and reacted at 25-300°C, preferably 80-180°C, for 0.5-20 h, preferably 0.5-3 h, to obtain the pretreated crude product.

[0072] In some embodiments of the present invention, in step A, the mass-to-volume ratio of the lignocellulose to the pretreatment agent is 1:20 to 20:1, preferably 1:5 to 1:20, and for example, may be further preferably 1:5, 1:12, 1:8, 1:10, or 1:20.

[0073] In this invention, the lignocellulose includes one or more of sweet sorghum straw residue, sugarcane bagasse, and corn straw residue; preferably, the lignocellulose is in powder form; more preferably, the particle size of the powdered lignocellulose is 60 mesh or larger.

[0074] According to a second aspect of the present invention, the method for enzymatic hydrolysis of lignocellulose includes: mixing lignocellulose residue with an enzymatic hydrolysis buffer, adding cellulase, stirring evenly, adjusting the pH, and performing enzymatic hydrolysis to obtain an enzymatic hydrolysate based on carbon-based ash water washing buffer salt.

[0075] The enzymatic hydrolysis buffer solution is obtained by adjusting the pH value of the carbon-based fuel combustion ash washing solution to 4-7, preferably 4-6, more preferably 4.5-5.5, and even more preferably 4.8-5.0, as described in the first aspect of the present invention. The pH of the carbon-based fuel combustion ash washing solution is adjusted by adding solid or aqueous solutions of inorganic acid or organic acid to the carbon-based fuel combustion ash washing solution and stirring.

[0076] According to the present invention, in the enzymatic hydrolysis process of the above-mentioned lignocellulose, the hydrolysis temperature can be specifically 40-60°C, and the hydrolysis time is preferably 24h-120h, more preferably 36h-108h, and most preferably 48h-84h.

[0077] In this invention, the enzymatic hydrolysis is preferably carried out on a shaker, and the rotation speed of the shaker is preferably 150 rpm to 250 rpm, more preferably 175 rpm to 225 rpm, and most preferably 200 rpm.

[0078] In some embodiments of the present invention, the amount of cellulase used is 0.1-80 FPU / g lignocellulose residue; preferably 2-30 FPU / g lignocellulose residue, more preferably 10-25 FPU / g lignocellulose residue, even more preferably 10-20 FPU / g lignocellulose residue, and most preferably 20 FPU / g lignocellulose residue.

[0079] According to the present invention, the lignocellulose residue includes lignocellulose pretreated residue and / or other lignocellulose pretreated residue obtained by the lignocellulose pretreatment method described in the first aspect of the present invention.

[0080] In this invention, the "other lignocellulose pretreatment residue" is a solid residue obtained after pretreating lignocellulose raw materials through physical or chemical pretreatment using one or more of organic alkalis, inorganic alkalis, organic acids, inorganic acids, organic solvents, and salts as pretreatment agents; wherein the organic alkalis include one or more of ethylenediamine, ethanolamine, methylamine, urea, and ammonia water; and / or, the inorganic alkalis include one or more of sodium hydroxide, potassium hydroxide, calcium oxide, and calcium hydroxide; and / or, the organic acids include one of formic acid, acetic acid, butyric acid, lactic acid, and benzenesulfonic acid. The inorganic acid includes one or more of hydrochloric acid, phosphoric acid, sulfuric acid, and nitric acid; the organic solvent includes one or more of methanol, ethanol, ethylene glycol, and glycerol; the salt includes one or more of choline chloride, betaine, triethylammonium sulfate, magnesium chloride, ferric chloride, and calcium chloride; the lignocellulose raw material includes, but is not limited to, agricultural waste such as corn stalks, wheat stalks, cotton stalks, sesame stalks, rapeseed stalks, sweet sorghum stalks, corn cobs, rice husks, millet husks, bagasse, rice straw, sawdust, hardwood, and softwood.

[0081] According to an embodiment of the third aspect of the present invention, the method for producing the bio-based chemical comprises: adjusting the pH of the nutrient source mixture to the pH required for fermentation, introducing a fermentation strain for producing the bio-based chemical into the mixture, and carrying out fermentation culture to produce the bio-based chemical; wherein the nutrient source mixture comprises an enzymatic hydrolysate based on carbon-based ash water washing buffer obtained in the method for enzymatic hydrolysis of lignocellulose described in the second aspect of the present invention and / or the carbon-based fuel combustion ash water washing liquid described in the first aspect of the present invention.

[0082] In this invention, the nutrient source mixture further comprises a carbon source; preferably, the carbon source comprises glucose and / or xylose.

[0083] In this invention, the fermentation strains include strains capable of fermenting and producing bio-based chemicals (such as ABE, ethanol, lactic acid, etc.), or genetically engineered strains capable of fermenting and producing bio-based chemicals (such as ABE, ethanol, lactic acid, etc.), such as yeast, lactic acid bacteria, Escherichia coli, Clostridium, etc.

[0084] In this invention, the fermentation can be single-strain fermentation or co-fermentation of strains that produce one or more bio-based chemicals.

[0085] According to some specific embodiments of the present invention, a method for preparing bio-based chemicals (e.g., ABE, ethanol, lactic acid) by fermentation of lignocellulose is provided. Figure 1 As shown, it includes the following steps:

[0086] (1) The pretreatment agent and the crushed lignocellulose are thoroughly mixed to form a solid-liquid mixture, and then stirred and reacted to obtain the pretreated crude product;

[0087] (2) Separate, wash and dry the solids in the pretreated crude product to obtain dried pretreated lignocellulose residue.

[0088] (3) Mix the pretreated lignocellulose residue with the enzymatic hydrolysis buffer, add cellulase, stir evenly, adjust the pH, and carry out enzymatic hydrolysis to obtain an enzymatic hydrolysate based on carbon-based ash water washing buffer salt.

[0089] (4) Adjust the pH of the nutrient source mixture to the pH required for fermentation, inoculate it with fermentation strains that produce bio-based chemicals, carry out fermentation culture, and produce bio-based chemicals;

[0090] The pretreatment agent is either the carbon-based fuel combustion ash washing liquid described in the first aspect of the present invention or a combination of the carbon-based fuel combustion ash washing liquid described in the first aspect of the present invention and one or more of organic bases, inorganic bases, organic acids, inorganic acids, organic solvents and salts.

[0091] In this invention, the enzymatic hydrolysis buffer is the carbon-based fuel combustion ash washing solution described in the first aspect of this invention, also referred to as the enzymatic hydrolysis buffer salt in this invention.

[0092] In some embodiments of the present invention, the lignocellulose residue includes the lignocellulose pretreated residue obtained in step (2) above and / or other lignocellulose pretreated residues.

[0093] In some embodiments of the present invention, the nutrient source mixture comprises the enzymatic hydrolysate based on carbon-based ash washing buffer salt obtained in step (3) above and / or the carbon-based fuel combustion ash washing liquid described in the first aspect of the present invention.

[0094] In this invention, the nutrient source mixture further comprises a carbon source; preferably, the carbon source comprises glucose and / or xylose.

[0095] Example

[0096] To make the present invention easier to understand, it will be further described in detail below with reference to the accompanying drawings and embodiments. These embodiments are for illustrative purposes only and are not intended to limit the scope of application of the present invention. Unless otherwise specified, the raw materials or components used in the present invention can be obtained commercially or by conventional methods.

[0097] The carbon-based fuel ash used in the following examples comes from a thermal power plant and is the residual ash after co-firing biomass and coal. The metal and non-metal components contained therein are shown in Table 1, as determined by inductively coupled plasma (ICP) elemental analysis. Among them, in addition to oxygen, the most abundant element is potassium at 10.73 wt%, followed by calcium, then magnesium and phosphorus. Other elements include aluminum, iron, manganese, zinc, etc. These elements mostly exist in the form of oxides or carbonates, which not only show alkaline properties but also provide potential for buffer systems of enzymatic hydrolysis buffer salts and microbial nutrients.

[0098] Table 1. Content of metallic and non-metallic elements in ash from power plants

[0099] Contained elements Quality percentage Si 0.08％ Ca 5.15％ Al 0.63％ K 10.73％ Mg 3.92％ Fe 1.06％ Na 0.11％ Mn 0.22％ Zn 0.03％ P 3.28％ N 0.01％ C 1.99％ H 0.20％ S 0.70％ O 15.98％

[0100] Example 1: Enzymatic hydrolysis and saccharification of sweet sorghum straw treated with biomass ash water washing solution.

[0101] (1) Preparation of solution containing carbon-based fuel combustion ash: Water and carbon-based fuel combustion ash were mixed in a 1:1 mass ratio and ultrasonically washed at 100°C for 10 minutes. The solution was obtained by vacuum filtration (i.e., solution containing carbon-based fuel combustion ash). The pH value was measured to be about 12.1 and used as a pretreatment agent. The concentration of each element in the solution was detected by an inductively coupled plasma (ICP) elemental analyzer, as shown in Table 2.

[0102] Table 2 Concentrations of metallic and non-metallic elements in ash washing liquor from power plants

[0103] Contained elements Concentration (mg / L) Na 908 K 7194 Ca 1295 Mg 3.972 P 0.135 S 887 Fe 0.006 Mn 0.005 Zn 0.005

[0104] (2) Oven-dried sweet sorghum straw residue (lignocellulose) with a particle size greater than 60 mesh was collected. The straw residue was washed with water to completely remove free sugars before drying. The oven-dried sweet sorghum residue was mixed with the prepared pretreatment agent at a solid-liquid ratio of 1:10 (w / v) and maintained at 180℃ and 500 rpm for 1 h. After cooling to room temperature, the solid phase was obtained by vacuum filtration. The solid phase was washed with deionized water until its surface was neutral (pH=7) and dried overnight at 105℃ until oven-dried. The solid recovery rate of the pretreated lignocellulose residue was calculated to be 62.4%, and the lignin removal rate in the raw material was 52.5%.

[0105] The dried pretreated sweet sorghum residue powder (lignocellulose pretreated residue) was mixed with a pre-prepared 0.05M citric acid / sodium citrate (pH=4.7) buffer solution, with a solid addition amount (e.g., pretreated sweet sorghum residue) of 6%. Cellulase (purchased from Novozymes) was added at a rate of 20 FPU / g solid. After thorough mixing, the mixture was enzymatically hydrolyzed at 50°C and 200 rpm for 72 h. The supernatant was collected by centrifugation, and the glucose and xylose concentrations in the hydrolysate were analyzed by high-performance liquid chromatography. The final glucose and xylose concentrations were found to be 33.55 g / L and 6.3 g / L, respectively.

[0106] Comparative Example 1:

[0107] (1) Add 0.5g of sodium hydroxide solid to 1 liter of water to prepare a pretreatment agent and measure the pH value to reach about 12.1.

[0108] (2) Oven-dried sweet sorghum straw residue (lignocellulose) with a particle size greater than 60 mesh was collected. The straw residue was washed with water to completely remove free sugars before drying. The oven-dried sweet sorghum residue was mixed with the prepared pretreatment agent at a solid-liquid ratio of 1:10 (w / v) and maintained at 180℃ and 500rpm for 1 hour. After cooling to room temperature, the solid phase was obtained by vacuum filtration. The solid phase was washed with deionized water until its surface was neutral (pH=7) and dried overnight at 105℃ until oven-dried. The calculated solid recovery rate of the pretreated lignocellulose residue was 65.2%, and the lignin removal rate in the raw material was 57.6%.

[0109] The dried, pretreated sweet sorghum residue powder was mixed with a pre-prepared 0.05M citric acid / sodium citrate (pH=4.8) buffer solution, with a solid addition amount of 6%. Cellulase (purchased from Novozymes) was added at a concentration of 20 FPU / g solid. After thorough mixing, the mixture was enzymatically hydrolyzed at 50℃ and 200 rpm for 72 h. The supernatant was collected by centrifugation, and the glucose and xylose concentrations in the hydrolysate were analyzed by high-performance liquid chromatography (HPLC). The final glucose and xylose concentrations were determined to be 31.42 g / L and 6.1 g / L, respectively.

[0110] Comparative Example 2:

[0111] Oven-dried sweet sorghum straw residue (lignocellulose) with a particle size greater than 60 mesh was collected. The residue was washed with water to completely remove free sugars before drying. The oven-dried sweet sorghum residue was mixed with water at a solid-liquid ratio of 1:10 (w / v) and maintained at 180℃ and 500 rpm for 1 hour. After cooling to room temperature, the solid phase was obtained by vacuum filtration. The solid phase was washed with deionized water until its surface was neutral (pH=7) and dried overnight at 105℃ until oven-dried. The calculated solid recovery rate of the pretreated lignocellulose residue was 62.4%, and the lignin removal rate from the raw material was 22.6%.

[0112] The dried, pretreated sweet sorghum residue powder was mixed with a pre-prepared 0.05M citric acid / sodium citrate (pH=4.7) buffer solution, with a solid addition amount of 6%. Cellulase (purchased from Novozymes) was added at a solid concentration of 20 FPU / g. After thorough mixing, the mixture was enzymatically hydrolyzed at 50℃ and 200 rpm for 72 h. The supernatant was collected by centrifugation, and the glucose and xylose concentrations in the hydrolysate were analyzed by high-performance liquid chromatography (HPLC). The final glucose and xylose concentrations were determined to be 30.35 g / L and 4.7 g / L, respectively.

[0113] Example 2: Pretreatment of corn straw residue by mixing biomass ash solution with ethanol.

[0114] The pretreatment agent obtained in Example 1 was mixed with ethanol at a ratio of 1:1 (v / v). Oven-dried corn straw residue with a particle size greater than 60 mesh was mixed with the prepared water washing solution and ethanol mixture at a solid-liquid ratio of 1:10 (w / v). The solid-liquid mixture was heated to 160°C and maintained at 500 rpm for 90 min. After cooling to room temperature, the solid phase was obtained by vacuum filtration. The solid phase was washed with deionized water until its surface was neutral (pH = 7) and dried overnight at 105°C until oven-dry. The calculated solid recovery rate of lignocellulose was 56.7%, and the lignin removal rate was 88.2%.

[0115] The dried, pretreated corn stalk residue powder was mixed with a pre-prepared 0.05M citric acid / sodium citrate (pH=4.8) buffer solution, with a solid addition amount of 6%. Cellulase (purchased from Novozymes) was added at a concentration of 20 FPU / g solid. After thorough mixing, the mixture was enzymatically hydrolyzed at 50℃ and 200 rpm for 72 h. The supernatant was collected by centrifugation, and the glucose and xylose concentrations in the hydrolysate were analyzed by high-performance liquid chromatography (HPLC). The final glucose and xylose concentrations were found to be 35.79 g / L and 10.26 g / L, respectively.

[0116] Example 3: Using ash water washing liquid from carbon-based fuel combustion to prepare a cellulase hydrolysis buffer and achieve enzymatic hydrolysis, saccharification, and ABE fermentation of sugarcane straw residue pretreated with ethylenediamine.

[0117] After juicing, the sugarcane straw was rinsed with deionized water until no residual free sugar remained on the surface, and then dried to absolute dryness at 105°C. It was then pulverized to a particle size of less than 40 mesh. The sugarcane straw residue was thoroughly mixed with a pre-prepared 10% (w / v) ethylenediamine aqueous solution and pretreated at 120°C for 1 hour. The reactor was then cooled to room temperature and centrifuged at 10,000 rpm to obtain solid sugarcane straw pretreatment residue. The residue was rinsed with deionized water until the surface was neutral. The resulting neutral residue was dried to absolute dryness at 105°C. The solid yield was measured to be 49.8%, and the contents of cellulose, hemicellulose, and lignin in the solid residue were 59.8%, 18.8%, and 13.9%, respectively.

[0118] The dried sugarcane straw pretreatment residue was mixed with a pre-prepared washing liquid containing carbon-based fuel combustion ash at a solids addition rate of 6% (w / v). The pH of the solid-liquid mixture was then adjusted to 4.8 with an acidic aqueous solution. Cellulase (purchased from KDN Group) at 20 FPU / g of the pretreatment residue was added to the pH-adjusted solid-liquid mixture. Enzymatic hydrolysis was then performed at 50°C and 180 rpm for 72 h. After hydrolysis, the hydrolysate was filtered through a 400-mesh nylon filter cloth to obtain the supernatant. The concentrations of glucose and xylose in the supernatant were determined by high-performance liquid chromatography to be 32.9 g / L and 9.2 g / L, respectively.

[0119] The pH of the enzymatic hydrolysis supernatant was adjusted to 7 using concentrated ammonia. Then, *Clostridium beijerinckii* seed culture (CGMCC; 1.5077; *Clostridium beijerinckii*) was inoculated at a 5% (v / v) inoculum. The seed culture medium formulation was as follows: glucose 40 g / L, potassium monohydrogen phosphate 0.5 g / L, potassium dihydrogen phosphate 0.5 g / L, ammonium acetate 2.2 g / L, p-aminobenzoic acid 1 mg / L, biotin 0.01 mg / L, magnesium sulfate 0.2 g / L, manganese sulfate 0.01 g / L, ferrous sulfate 0.01 g / L, sodium chloride 0.01 g / L. An anaerobic environment was constructed using sterile nitrogen.

[0120] After inoculation, sterile high-purity nitrogen (>99.999%) was continuously purged into the fermenter for 2 hours to establish an anaerobic fermentation environment. Subsequently, batch fermentation continued at 37°C and 50 rpm for 72 hours. After fermentation, the fermentation supernatant was centrifuged and prepared as a sample. The concentrations of glucose and xylose in the fermentation supernatant were detected using high-performance liquid chromatography (HPLC), and the concentrations of ABE and organic acid byproducts such as acetic acid and butyric acid were detected using gas chromatography (GC). No glucose or xylose residues were found in the fermentation supernatant. The concentrations of acetone, butanol, and ethanol in the fermentation broth were 3.4 g / L, 11.8 g / L, and 1.7 g / L, respectively. The concentrations of acetic acid and butyric acid in the fermentation broth were 2.4 g / L and 1.3 g / L, respectively.

[0121] Example 4: An enzymatic hydrolysis buffer solution was prepared using the washing liquid of ash from carbon-based fuel combustion, and then ethanol fermentation was carried out.

[0122] The prepared enzymatic hydrolysate from Example 1 was taken, and the pH of the supernatant was adjusted to 5.5 using an alkaline solution. Then, *Saccharomyces cerevisiae* was inoculated at a rate of 10% (v / v). Ethanol fermentation was carried out using laboratory-preserved *Saccharomyces cerevisiae* M 3013 (application number 202411104744 8, an engineered strain capable of efficiently metabolizing xylose and producing high-concentration ethanol in undetoxified lignocellulose hydrolysate with high inhibitor concentrations and without any added nutrients) and its derivatives. The strain was stored on slant at 4°C and subcultured every 2–3 months. The ethanol seed culture medium A consisted of 30 g / L glucose, 3 g / L yeast extract, and 5 g / L beef peptone. The fermentation medium consisted of 60 g / L glucose, 8 g / L beef peptone, 6 g / L MgSO4, and 3 g / L KH2PO4. The pH was adjusted to 5.5 using NaOH. Before fermentation, sterilize at 121℃ for 20 minutes.

[0123] Concentrated ammonia was added to the diluted concentrated fermentation broth to adjust the pH to 5. Then, sugarcane straw residue pretreated with the ethylenediamine aqueous solution described in Example 1 was mixed with the pH-adjusted carbon-based fuel combustion ash washing liquid at a solids addition rate of 6% (w / v). Cellulase (purchased from Novozymes) at 20 FPU / g solids residue was added. The solid-liquid mixture was enzymatically hydrolyzed at 55°C and 200 rpm for 72 h. The mixture was then filtered through a 400-mesh nylon filter to obtain the enzymatic supernatant. Concentrated ammonia was added to the enzymatic supernatant to adjust its pH to 5.5. A pre-cultured *Saccharomyces cerevisiae* seed culture was inoculated at a 10% (w / v) inoculum. The initial fermentation broth after inoculation contained 32.7 g / L glucose and 9.6 g / L xylose, respectively. The fermentation apparatus was incubated at 28°C and 300 rpm for 48 h. After fermentation was terminated, the fermentation broth was centrifuged, and the concentrations of glucose and xylose in the supernatant were measured to be 0.4 g / L and 1.2 g / L, respectively. The concentration of ethanol in the fermentation broth was 18.5 g / L.

[0124] Example 5: A fermentation medium containing nutrients was prepared using the ash and water washing liquid from the combustion of carbon-based fuels, and then ethanol fermentation was carried out.

[0125] In the first group, the carbon-based fuel combustion ash washing liquid obtained in Example 1 was mixed with 30 g / L glucose and 3 g / L beef peptone, and the pH was adjusted to 5.5 using dilute sulfuric acid. In the second group, the carbon-based fuel combustion ash washing liquid obtained in Example 1 was mixed with 30 g / L glucose and 3 g / L beef peptone, and the pH was adjusted to 5.5 using dilute sulfuric acid. The third group used an ethanol fermentation medium containing 30 g / L glucose, 3 g / L beef peptone, 3 g / L MgSO4, and 1.5 g / L KH2PO4. 4， The pH was adjusted to 5.5 using NaOH. In the fourth group, the carbon-based fuel combustion ash washing liquid obtained in Example 1 was supplemented with 30 g / L glucose, 3 g / L beef peptone, 3 g / L MgSO4, and 1.5 g / L KH2PO4, and the pH was adjusted to 5.5 using dilute sulfuric acid. The fifth group used an ethanol fermentation medium without a nitrogen source, containing 30 g / L glucose, 3 g / L MgSO4, and 1.5 g / L KH2PO4. 4， Before fermentation, the four culture media were sterilized at 121℃ for 20 min. The ethanol seed culture medium formula was 30 g / L glucose, 3 g / L yeast extract, and 5 g / L beef peptone. Pre-cultured *Saccharomyces cerevisiae* seed culture was inoculated at a 10% (w / v) inoculum. The fermentation apparatus was then incubated at 28℃ and 300 rpm for 48 h. After fermentation was terminated, the fermentation broth was centrifuged, and the ethanol concentrations were measured as follows: Group 1: 9.4 g / L; Group 2: 13.8 g / L; Group 3: 13.9 g / L; Group 4: 13.5 g / L; and Group 5: 9.1 g / L. These results demonstrate that, using only carbon-based fuel combustion ash and water as nutrients, with the addition of a nitrogen source, the same sugar-alcohol conversion rate as the ethanol fermentation medium can be achieved. Carbon-based fuel combustion ash and water can provide nutrients for the ethanol fermentation process.

[0126] Example 6: Enzymatic hydrolysis of wheat straw and lactic acid fermentation using ash water from carbon-based fuel combustion as a buffer solution.

[0127] Wheat straw was crushed to a particle size of less than 40 mesh, then thoroughly mixed with a pre-prepared washing solution of carbon-based fuel combustion ash, and pretreated at 120°C for 1 hour. Afterward, the reactor was cooled to room temperature and centrifuged at 10,000 rpm to obtain solid wheat straw pretreatment residue. The residue was washed with deionized water until the surface was neutral. The resulting neutral residue was then dried to oven dryness at 105°C.

[0128] The pretreated residue obtained from the reaction was added to a buffer solution at a solids addition rate of 10% (w / v) with a pH of 4.8. After thorough mixing, cellulase at a concentration of 20 FPU / g of residue was added to the resulting solid-liquid mixture, and the mixture was hydrolyzed at 50°C and 200 rpm for 72 h. The supernatant was then collected by centrifugation. The glucose and xylose concentrations in the hydrolysate were 48.2 g / L and 16.2 g / L, respectively. The pH of the hydrolysate was adjusted to 6.5 using a 4M potassium hydroxide aqueous solution.

[0129] Lactobacillus rhamnosus (ATCC53103) was inoculated into the pH-adjusted enzymatic digestion supernatant at a 10% (v / v) inoculation rate. The Lactobacillus rhamnosus culture medium formulation was as follows: 40 g L⁻¹ glucose, 20 g L⁻¹ yeast extract, 0.01 g L⁻¹... -1 Sodium chloride, 0.5 g / L -1 Sodium acetate, 0.2 g / L -1 Ammonium citrate, 0.2 g / L -1 Potassium dihydrogen phosphate, 0.2 g / L -1 Magnesium sulfate heptahydrate, 0.05 g / L -1 Manganese sulfate heptahydrate, 15g / L -1 Calcium carbonate.

[0130] After inoculation, the fermentation apparatus was placed in a constant temperature incubator at 50℃ and fermented in a shaker at 150 rpm for 70 hours. Fermentation was then terminated. The fermentation supernatant was collected. The lactic acid concentration in the fermentation supernatant was detected by gas chromatography. The lactic acid concentration in the fermentation broth was 43.4 g / L.

[0131] Example 7: Comparison of the saccharification effect of different enzymatic hydrolysis buffer solutions on alkaline treatment of corn straw

[0132] Oven-dried corn stalks with a particle size of 60 mesh or less were mixed with a 1.5% (w / v) sodium hydroxide solution at a solids addition rate of 10% (w / v) and stirred thoroughly. The resulting solid-liquid mixture was placed in a closed high-pressure reactor and reacted at 120°C and 200 rpm for 90 min. The pretreated black liquor was then removed using a 400-mesh nylon filter cloth, and the pretreated solid phase was washed with deionized water until the pH of the solid surface reached 7. The mixture was then dried overnight at 105°C. The above experimental procedure was repeated in six groups.

[0133] The six pretreated and dried residues were mixed with 50 mM solutions of phosphate / dipotassium hydrogen phosphate, acetic acid / potassium acetate, carbon-based fuel combustion ash washing liquid, citric acid / sodium citrate, and deionized water (control group) at a solid addition rate of 6% (w. / v). After thorough mixing, 15 FPU / g solid cellulase (purchased from Novozymes) was added sequentially. The resulting solid-liquid mixtures were enzymatically hydrolyzed at 55℃ and 200 rpm for 72 h. Afterward, the mixtures were centrifuged at 10000 rpm to obtain the supernatant. The concentrations of glucose and xylose in the supernatant after enzymatic hydrolysis were determined by high-performance liquid chromatography (HPLC), and the results are shown in Table 3.

[0134] Table 3 Comparison of sugar content in the cellolysate of corn straw treated with different enzymatic buffer solutions and alkaline methods.

[0135]

[0136] As shown in Table 3, when carbon-based fuel combustion ash washing liquid is used as a buffer to replace the traditional acetic acid / sodium acetate and citric acid / sodium citrate buffers, the sugar concentration obtained by enzymatic hydrolysis is basically consistent with that obtained by the traditional method, proving that carbon-based fuel combustion ash washing liquid can be used as a fiber enzymatic hydrolysis buffer.

[0137] Example 8: Semi-synchronous saccharification and ABE fermentation of alkaline pretreated sweet sorghum straw using different enzymatic hydrolysis buffer solutions.

[0138] Sorghum residue was washed with water until all free sugars on the surface were removed, then dried completely and pulverized. Sorghum residue with a particle size of 80 mesh or less was mixed with a 1% (w / v) potassium hydroxide solution at a solids addition rate of 5% (w / v) and stirred thoroughly. The resulting solid-liquid mixture was placed in a closed high-pressure reactor and reacted at 100°C and 200 rpm for 2 hours. Afterward, the pretreated black liquor was removed using a 400-mesh nylon filter cloth, and the pretreated solid phase was washed with deionized water until the pH of the solid surface reached 7. Finally, it was dried overnight at 105°C. The above experimental procedure was repeated in 5 groups.

[0139] The five pretreated and dried residues were mixed with 50 mM solutions of phosphate / dipotassium hydrogen phosphate, acetic acid / potassium acetate, butyric acid / potassium butyrate, citric acid / potassium citrate, and deionized water (control group) at pH 4.8 at a solid addition rate of 6% (w / v). After thorough mixing, 15 FPU / g solid cellulase (purchased from Novozymes) was added sequentially. The resulting solid-liquid mixtures were enzymatically hydrolyzed at 55°C and 200 rpm for 36 h. Subsequently, the pH of the hydrolysis system was adjusted to 6.5 with concentrated ammonia, and the temperature of the hydrolysate was rapidly reduced to 37°C. After cooling, a pre-cultured Clostridium acetone-butanol seed culture (OD200) was added to the hydrolysate at an inoculum rate of 10% (v / v). 600>0.8, Clostridium acetobutylicum (ABE 1201) was preserved in the laboratory, and sterile high-purity nitrogen gas (>99.999%) was continuously purged into the fermenter for more than 2 hours to create an anaerobic environment. The culture medium formula for the Clostridium acetobutylicum seed culture was as follows: glucose 35 g / L, yeast extract 3 g / L, beef peptone 2 g / L, magnesium sulfate 0.2 g / L, potassium monohydrogen phosphate 1 g / L, potassium dihydrogen phosphate 1 g / L, ammonium acetate 2 g / L.

[0140] After inoculation, fermentation continued at 37℃ and 50 rpm for 96 h. After fermentation, unhydrolyzed cellulose residue and bacterial cells were removed by centrifugation, yielding the fermentation supernatant. High-performance liquid chromatography (HPLC) was used to detect glucose and xylose in the fermentation supernatant, and gas chromatography (GC) was used to detect ABE and acetic acid and butyric acid byproducts. The results are shown in Table 4.

[0141] Table 4 Comparison of semi-simultaneous saccharification and ABE fermentation results of different enzymatic hydrolysis buffer solutions on alkaline pretreated sweet sorghum straw.

[0142]

[0143] As shown in Table 4, under the carbon-based fuel combustion ash water washing liquid buffer salt system, after semi-synchronous saccharification and fermentation of sweet sorghum straw residue, the ABE fermentation concentration was similar to that of the phosphate buffer solution, proving that under the same addition amount, carbon-based fuel combustion ash water washing liquid buffer salt can be used as a nutrient for ABE fermentation.

[0144] It should be noted that the embodiments described above are merely preferred embodiments of the present invention, used to explain the present invention, and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the terms used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications having the same function.

Claims

1. A carbon-based fuel combustion ash water washing solution, which is a liquid mixture containing carbon-based fuel combustion ash and / or carbon-based fuel combustion ash leachate.

2. The carbon-based fuel combustion ash water wash solution of claim 1, wherein, The source of the carbon-based fuel combustion ash includes one or more of direct open burning, boiler combustion, biomass pyrolysis gasification, liquefaction process, power generation of shaped biomass particles, and heat collection device; preferably, the source of the carbon-based fuel combustion ash includes one or more of fly ash, coal combustion residue, biomass shaped particle combustion, biomass pyrolysis gasification, liquefaction, and bottom ash or fly ash after coal tar combustion.

3. The carbon-based fuel combustion ash water washing solution according to claim 2, wherein the liquid mixture containing carbon-based fuel combustion ash leachate is a solid-liquid mixture containing insoluble solid phase particles obtained by mixing the carbon-based fuel combustion ash with a liquid phase substrate; preferably, the amount of dissolved carbon-based fuel combustion ash in the liquid mixture containing carbon-based fuel combustion ash leachate is 0.5% to 50% (mass / volume); or the liquid mixture containing carbon-based fuel combustion ash leachate is a supernatant or colloidal solution without solid residue obtained by dissolving the soluble components and solid-liquid separation after mixing the carbon-based fuel combustion ash with a liquid phase substrate; preferably, the pH of the liquid mixture containing carbon-based fuel combustion ash leachate is 6 to 14.

4. The carbon-based fuel combustion ash water washing solution according to claim 3, wherein the mass ratio of the liquid phase substrate to the carbon-based fuel combustion ash is 1:5 to 20:1; preferably, the liquid phase substrate includes one or more of water, alcohol, ester, ketone, ether, ionic liquid, organic acid, dilute inorganic acid, furan compound, and tetrahydrofuran; further preferably, the liquid phase substrate is in a single phase state or two-phase state or three-phase state; more preferably, the liquid phase substrate is in a liquid state at a temperature of ≤50°C; and / or the mixing treatment is performed using ultrasonic mixing, the temperature of the mixing treatment is 50-140°C, and the time of the mixing treatment is 5-20 min.

5. Use of the carbon-based fuel combustion ash water washing solution according to any one of claims 1-4 in a biomass sugar conversion and process, which includes one or more of lignocellulose pretreatment, lignocellulose enzymatic hydrolysis, and bio-based chemical production. The method of lignocellulose pretreatment includes: Step A: mixing a pretreatment agent with crushed lignocellulose to form a solid-liquid mixture, and then stirring and reacting to obtain a pretreatment crude product; Step B: separating, washing, and drying the solid material in the pretreatment crude product to obtain dried lignocellulose pretreatment residue; wherein the pretreatment agent is the carbon-based fuel combustion ash water washing solution according to any one of claims 1-4 or a combination of the carbon-based fuel combustion ash water washing solution according to any one of claims 1-4 and one or more of organic base, inorganic base, organic acid, inorganic acid, organic solvent, and salt.

7. The use according to claim 6, wherein the lignocellulose pretreatment is carried out at a temperature of 50-140°C. ​ ​ 6. Use according to claim 5, characterized in that, ​ ​ ​ ​ ​ In step A, the mass and volume ratio of the lignocellulose to the pretreatment agent is 1:20 to 20:1; And / or, the reaction is at 25-300℃, preferably 80-180℃; and / or, the reaction time is 0.5-20h, preferably 0.5-3h; And / or, the organic base includes one or more of ethylenediamine, ethanolamine, methylamine, urea and ammonia; and / or, the inorganic base includes one or more of sodium hydroxide, potassium hydroxide, calcium oxide and calcium hydroxide; and / or, the organic acid includes one or more of formic acid, acetic acid, butyric acid, lactic acid, benzene sulfonic acid; and / or, the inorganic acid includes one or more of hydrochloric acid, phosphoric acid, sulfuric acid, nitric acid; and / or, the organic solvent includes one or more of methanol, ethanol, ethylene glycol and glycerol; and / or, the salt includes one or more of choline chloride, betaine, triethylammonium sulfate, magnesium chloride, ferric chloride, calcium chloride.

8. Use according to claim 5, characterized in that, The method for lignocellulose enzymolysis includes: mixing lignocellulose residues with an enzymolysis buffer, adding cellulase, stirring uniformly, adjusting pH, performing enzymolysis, and obtaining an enzymolysis solution based on carbon-based ash water washing buffer salt; The enzymolysis buffer is carbon-based fuel combustion ash water washing solution.

9. The use according to claim 8, wherein The pH value of the enzymolysis buffer is 4-7, preferably 4-6, further preferably 4.5-5.5, and more further preferably 4.8-5.0; And / or, the cellulase is used in an amount of 0.1-80 FPU / g lignocellulose residues; preferably 2-30 FPU / g lignocellulose residues, further preferably 10-25 FPU / g lignocellulose residues, and more further preferably 10-20 FPU / g lignocellulose residues; And / or, the lignocellulose residues include lignocellulose pretreatment residues obtained by the method for lignocellulose pretreatment according to any one of claims 6-8 and / or other lignocellulose pretreatment residues.

10. Use according to claim 5, characterized in that, The method for producing bio-based chemicals includes: adjusting the pH of a nutrient source mixture to a pH required for fermentation, inoculating a fermentation strain producing bio-based chemicals into the nutrient source mixture, performing fermentation culture, and producing bio-based chemicals; The nutrient source mixture comprises the enzymolysis solution based on carbon-based ash water washing buffer salt obtained by the method for lignocellulose enzymolysis according to claim 8 or 9 and / or the carbon-based fuel combustion ash water washing solution according to any one of claims 1-4. Preferably, the nutrient source mixture further comprises a carbon source; the carbon source includes glucose and / or xylose.

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