Biomass alcohol-oil mixed fuel and preparation method thereof

Abstract

The invention relates to a biomass alcohol-oil mixed fuel and a preparation method thereof, and belongs to the technical field of energy and chemical industry and biomass fuels, and the biomass alcohol-oil mixed fuel comprises the following raw materials by weight: 30-50 parts of methanol; 35 to 55 parts of biomass oil; 10 to 20 parts of a modified solubilizer; 0.5 to 2 parts of a compound auxiliary agent; wherein the modified solubilizer is a grafted copolymer prepared by carrying out alcoholysis reaction on biomass oil and polyhydric alcohol under the action of a basic catalyst to obtain an intermediate and then carrying out ring-opening polymerization reaction on the intermediate and mixed gas consisting of epoxypropane and ethylene oxide under a closed condition; according to the scheme, a proper proportion of epoxypropane chain segments are introduced in the grafting process; different from a graft only containing ethylene oxide, the introduction of side methyl of epoxypropane increases the steric hindrance of a molecular chain, and a thicker solvation layer is formed on an oleyl-alcohol interface.

Description

Technical Field

[0001] This invention relates to the fields of energy, chemical industry and biomass fuel, specifically to a biomass alcohol-oil blended fuel and its preparation method. Background Technology

[0002] Biomass energy, as a renewable and clean energy source, is of great significance for alleviating the energy crisis and reducing environmental pollution when converted into liquid fuel to replace fossil fuels. Among many application schemes, biomass-methanol blended fuel, which combines biomass oil and methanol, has become a research hotspot in the field of industrial boilers and heavy-duty diesel engine fuel substitution because it can take into account both the high clean combustion characteristics of methanol and the high energy density of biomass oil. However, in practical applications and storage, existing biomass alcohol-oil blended fuel technologies have the following limitations: The physical stability of the system is a problem. Methanol is a polar solvent, while biomass oil is mainly composed of long-chain fatty acid esters or hydrocarbon mixtures, which are non-polar or weakly polar components, resulting in extremely poor compatibility between the two. Traditional preparation methods mainly rely on simple mechanical stirring or the addition of large amounts of commercially available traditional surfactants; however, in actual storage, such fuels are prone to macroscopic phase separation, often exhibiting obvious stratification within a short period of time. Even when using physically compounded emulsifiers, their adsorption strength at the oil-ethanol interface is weak, making it difficult to resist thermodynamic disturbances, resulting in a short fuel storage period and failing to meet the requirements for long-distance transportation and long-term storage. Safety performance and volatilization suppression issues: Methanol has a low boiling point and a high saturated vapor pressure. Methanol in a free state in blended fuels is highly volatile. This not only causes fluctuations in the lower heating value of the fuel during storage, but more seriously, it significantly reduces the flash point of the fuel. Existing blended fuels generally have low flash points, posing significant safety hazards in production, storage, and transportation. Furthermore, due to the diversity and complexity of biomass oil sources, such as acidified oil, gutter oil, or pine tar, these sources often contain a certain amount of water, impurities, and high acid values. The introduction of these inferior oil sources further deteriorates the stability of the system and poses a serious risk of oxidation and corrosion to metal storage and transportation containers and engine fuel systems. Existing blending technologies are unable to ensure stability while simultaneously taking into account the high energy density of the fuel and its adaptability to inferior oil sources. In summary, the existing technology lacks a biomass alcohol-oil blended fuel and its preparation method that can achieve long-term nanoscale stable dispersion of high proportion of methanol in the biomass oil phase, effectively suppress methanol volatilization, improve fuel safety performance and have good corrosion resistance.

[0003] The information disclosed in the background section above is only intended to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0004] The purpose of this invention is to provide a biomass alcohol-oil blended fuel and its preparation method to solve the problems mentioned in the background art.

[0005] The technical solution of this invention comprises the following raw materials in parts by weight: 30-50 parts methanol; 35-55 parts of biomass oil; 10-20 parts of modified solubilizer; Compound adjuvant 0.5-2 parts; The modified solubilizer is a polyether ester derivative with a hydrophilic-lipophilic balance value of 4-7, obtained by alcoholysis reaction of biomass oil and polyol under the action of alkaline catalyst, and then by ring-opening polymerization of the intermediate with a mixture of propylene oxide and ethylene oxide under closed conditions.

[0006] Preferably, the biomass oil is selected from at least one of waste animal and vegetable oils, acidified oils, fatty acid methyl esters, and pine tar; The biomass oil undergoes dehydration and impurity removal treatment before use, and its acid value is controlled to be ≤5mgKOH / g.

[0007] Preferably, the preparation steps of the modified solubilizer include: (1) Framework construction: Biomass oil and polyol are put into a reactor, and alkaline catalyst of 0.1wt%-0.3wt% relative to the total mass of biomass oil and polyol is added. The reaction is carried out at 180-220℃ for 1.5-2.5 hours to convert triglycerides into a mixture of monoglycerides and diglycerides containing free hydroxyl groups. Then the temperature is lowered to 110-130℃ for vacuum dehydration. (2) Grafting modification: Add an alkaline catalyst or Lewis acid catalyst to the mixture obtained in step (1), preferably an alkaline catalyst such as potassium hydroxide, sodium hydroxide, or sodium methoxide, or at least one of a Lewis acid catalyst such as boron trifluoride or zinc chloride. Introduce a mixture of propylene oxide and ethylene oxide, controlling the molar ratio of ethylene oxide to propylene oxide to be [value missing]. to The reaction was carried out under pressure of 0.3-0.5 MPa and temperature of 120-140℃ until the pressure in the reactor stopped decreasing. After neutralization and filtration, a modified solubilizer with a hydrophilic-lipophilic balance value of 4-7 was obtained.

[0008] Preferably, the polyol mentioned in step (1) is selected from glycerol or pentaerythritol; After the ring-opening polymerization reaction described in step (2) is completed, the process also includes adding an acidic catalyst and an organic acid, or directly adding an acid anhydride, to partially esterify and cap the hydroxyl groups at the end of the molecule under heating conditions after neutralizing the alkaline catalyst.

[0009] Preferably, the compound additives include combustion improvers and metal corrosion inhibitors; The combustion improver is selected from one or a combination of isooctyl nitrate, 2-ethylhexyl nitrate, and di-tert-butyl peroxide. The metal corrosion inhibitor is selected from one or a combination of benzotriazole and 2-[2-(8-heptadecenyl)-4,5-dihydro-1H-imidazol-1-yl]ethanol.

[0010] A method for preparing a biomass alcohol-oil blended fuel includes the following steps: (1) Oil phase premixing: Biomass oil and modified solubilizer are added to a mixing tank according to the weight parts described in claim 1, and mixed at low speed under the conditions of temperature 25-40℃ and stirring speed 300-500rpm to form a uniform oil phase base. (2) Alcohol phase injection: Turn on the shearing equipment and set the shearing rate to 1500-2800 rpm. Slowly inject methanol into the oil phase base under high-speed shearing to perform preliminary emulsification using mechanical shearing force. (3) Homogenization treatment: After the methanol injection is completed, add compound additives, keep the shear rate unchanged, and continue to perform cyclic shear emulsification for 15-30 minutes until the system is homogeneous and transparent or semi-transparent, thus obtaining biomass alcohol oil compound fuel.

[0011] Preferably, in step (2), the methanol injection process needs to control the flow rate to prevent excessively high local methanol concentration from causing demulsification; The shearing equipment is a high-shear emulsifier or a pipeline shearing pump.

[0012] This invention provides an improved biomass alcohol-oil blended fuel and its preparation method, which has the following improvements and advantages compared with the prior art: 1. This method introduces an appropriate proportion of propylene oxide (PO) segments during the grafting process; unlike grafts containing only ethylene oxide, the introduction of propylene oxide side methyl groups increases the steric hindrance of the molecular chain, forming a thicker solvation layer at the oleic alcohol interface. 2. This scheme establishes a dynamic equilibrium relationship between shear rate and dispersed phase concentration. By combining a specific high-speed shearing process with the chemical solubilization effect of the modified solubilizer, the droplet size is achieved within the thermodynamically stable range of micrometers. Detailed Implementation

[0013] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0014] Example 1: This invention provides a biomass alcohol-oil blended fuel, comprising the following raw materials in parts by weight: 30-50 parts methanol; 35-55 parts biomass oil; 10-20 parts modified solubilizer; and 0.5-2 parts compounding additives. The modified solubilizer is a graft copolymer prepared by alcoholysis of biomass oil and polyol under alkaline catalyst to obtain an intermediate, followed by ring-opening polymerization of the intermediate with a mixture of propylene oxide and ethylene oxide under closed conditions. The biomass oil is selected from at least one of waste animal and vegetable oils, acidified oils, fatty acid methyl esters, and pine tar. The biomass oil undergoes dehydration and impurity removal treatment before use, and its acid value is controlled to be ≤5 mg KOH / g. The preparation steps of the modified solubilizer include: (1) framework construction: put biomass oil and polyol into a reaction vessel, add alkaline catalyst at a ratio of 0.1wt%-0.3wt% relative to the total mass of biomass oil and polyol, and carry out constant temperature alcoholysis reaction at 180-220℃ for 1.5-2.5 hours to convert triglycerides into a mixture of monoglycerides and diglycerides containing free hydroxyl groups, and then cool down to 110-130℃ for vacuum dehydration; (2) graft modification: add alkaline catalyst or Lewis acid catalyst to the mixture obtained in step (1), preferably alkaline catalysts such as potassium hydroxide, sodium hydroxide, sodium methoxide, or at least one of Lewis acid catalysts such as boron trifluoride and zinc chloride; A mixture of propylene oxide and ethylene oxide is introduced, and the molar ratio of ethylene oxide to propylene oxide is controlled to be [value missing]. to The pressure ring-opening polymerization reaction was carried out under pressure of 0.3-0.5MPa and temperature of 120-140℃ until the pressure in the reactor no longer decreased. After neutralization and filtration, a modified solubilizer with a hydrophilic-lipophilic balance value of 4-7 was obtained. The compound additives include combustion improvers and metal corrosion inhibitors; the combustion improver is selected from one or a combination of isooctyl nitrate (or 2-ethylhexyl nitrate) and di-tert-butyl peroxide; the metal corrosion inhibitor is selected from one or a combination of benzotriazole and 2-[2-(8-heptadecenyl)-4,5-dihydro-1H-imidazol-1-yl]ethanol. A method for preparing biomass alcohol-oil blended fuel includes the following steps: (1) Oil phase premixing: biomass oil and modified solubilizer are added to a blending kettle according to the above weight parts, and stirred and mixed at low speed under the conditions of temperature 25-40℃ and stirring speed 300-500rpm to form a uniform oil phase base material; (2) Alcohol phase injection: turn on the shearing device, set the shearing rate to 1500-2800rpm, and slowly inject methanol into the oil phase base material under high-speed shearing state, and use mechanical shearing force to perform preliminary emulsification; (3) Homogenization treatment: after the methanol injection is completed, add compounding additives, keep the shearing rate unchanged, and continue to perform cyclic shearing emulsification for 15-30 minutes until the system is homogeneous and transparent or semi-transparent, thus obtaining biomass alcohol-oil blended fuel; The methanol injection process requires flow rate control to prevent excessively high local methanol concentrations from causing demulsification; the shearing equipment is a high-shear emulsifier or a pipeline shear pump. This embodiment provides a biomass alcohol-oil blended fuel, which is a preferred embodiment based on the above technical solution. Before formal preparation, the present invention experimentally determined the decay rate of the methanol-biomass oil interfacial tension under different HLB values ​​to determine the optimal alkylene oxide ratio and degree of polymerization. The model shows that when the HLB value is in the range of 4-7 and an appropriate proportion of propylene oxide (PO) segments are introduced into the molecular chain, the viscoelastic modulus of the interfacial film reaches its peak value, which can effectively resist thermodynamic disturbances. The biomass alcohol-oil blended fuel of this embodiment includes the following raw materials in parts by weight: 40 parts methanol; 44 parts biomass oil; 15 parts modified solubilizer; and 1 part compounding agent. The biomass oil is selected from acidified oil that has undergone dehydration and impurity removal treatment and whose acid value is controlled at 3 mg KOH / g. The preparation steps of the modified solubilizer include: (1) skeleton construction: acidified oil as biomass oil and glycerol as polyol are put into the reaction vessel, and sodium hydroxide of 0.2% relative to the total mass of biomass oil and polyol is added as an alkaline catalyst. The constant temperature alcoholysis reaction is carried out at 200°C for 2 hours. This step utilizes the high temperature alcoholysis mechanism to break the long chain structure of triglycerides and convert them into a mixture of monoglycerides and diglycerides containing abundant free hydroxyl groups, providing necessary active sites for subsequent grafting reactions. Then, the temperature is lowered to 120°C for vacuum dehydration to remove the water generated in the reaction and prevent side reactions from occurring. (2) Grafting modification: Potassium hydroxide is added to the mixture obtained in step (1) as an alkaline catalyst, and a mixture of propylene oxide and ethylene oxide is introduced to control the molar ratio of ethylene oxide to propylene oxide. 1.5, under pressure of 0.4 MPa and temperature of 130℃, a pressure ring-opening polymerization reaction was carried out until the pressure in the reactor no longer decreased. After neutralization and filtration, a modified solubilizer with a hydrophilic-lipophilic balance value of 5.5 was obtained. It should be noted that the HLB value of the modified solubilizer of this invention, i.e., the hydrophilic-lipophilic balance value, is determined by the Griffin method, and the calculation formula is as follows: in, The relative molecular mass of the hydrophilic segment in the modified solubilizer molecule, i.e., the polyethylene oxide segment; The value represents the number-average total relative molecular mass of the modified solubilizer molecules; the mass of the propylene oxide segment, as an oleophilic-hydrophobic unit, is included in the denominator. In, but not included in the numerator middle; The calculation logic is as follows: ,in The average molecular weight of the hydrophobic framework is calculated based on the saponification value test results of the raw biomass oil. and These represent the total mass of the propylene oxide and ethylene oxide segments introduced through the reaction, respectively. Meanwhile, to ensure the accuracy of industrial production, this embodiment also employs gas chromatography, referring to GB / T2988, to analyze unreacted epoxy monomers and byproducts in the product, calculate the actual grafting rate of ethylene oxide and propylene oxide, and use this to correct for errors. and The value is then substituted into the above formula to obtain the corrected actual HLB value; This embodiment also uses gas chromatography to analyze the composition distribution of the product in accordance with GB / T2988, and to assist in correcting the calculation results of HLB values. The compounded additives include 2-ethylhexyl nitrate in a weight ratio of 1:1, a combustion improver and benzotriazole, and a metal corrosion inhibitor. The preparation method includes: (1) Oil phase premixing: Biomass oil and modified solubilizer are added to the blending kettle according to the above weight parts, and low-speed stirring is carried out under the conditions of temperature 30℃ and stirring speed 400rpm to form a uniform oil phase base material; (2) Alcohol phase injection: Turn on the high shear emulsifier as shearing equipment, set the shear rate to 2000rpm, and slowly inject methanol into the oil phase base material under high-speed shearing state. The mechanical shearing force is used for preliminary emulsification. The flow rate of methanol injection needs to be controlled to prevent local methanol concentration from being too high and causing demulsification; (3) Homogenization treatment: After the methanol injection is completed, compound additives are added, the shear rate is kept constant, and cyclic shear emulsification is continued for 20 minutes until the system is homogeneous and transparent, thus obtaining biomass alcohol oil mixed fuel; In this embodiment, a specific fatty acid ester-polyether amphiphilic structure was constructed through in-situ synthesis of the modified solubilizer. The hydrophobic long chains derived from biomass formed a van der Waals anchor with the biomass oil substrate. Simultaneously, the grafted polyether segments firmly adsorbed methanol molecules through a hydrogen bond network, thus achieving a high proportion of methanol nanoscale dispersion in the oil phase without relying on large amounts of traditional emulsifiers. This solves the technical problems of easy stratification and easy volatility of methanol in traditional physically mixed fuels, making it suitable for industrial boilers and heavy-duty diesel engine fuel replacement scenarios. The selection criteria for process parameters are as follows: In this embodiment, the shear rate is set at 2000 rpm based on the balance between the microemulsion droplet size distribution and the shear energy. Experiments show that within the range of 1500-2800 rpm, the average droplet size of the microemulsion decreases exponentially with the increase of the shear rate. When the rate is below 1500 rpm, the droplet size is mostly distributed in the range of 5-10 micrometers, which is prone to aggregation and stratification. When the rate is above 2500 rpm, although the droplet size can reach the nanometer scale, the energy consumption increases dramatically and the system temperature rises significantly. A shear rate of 2000 rpm combined with 40 parts of methanol can control the droplet size within the optimal thermodynamic stability range of 0.5-2 micrometers, which ensures both the micro-explosion intensity during combustion and the economic efficiency of the preparation energy consumption.

[0015] Example 2: A biomass alcohol-oil blended fuel comprises the following raw materials in parts by weight: 30-50 parts methanol; 35-55 parts biomass oil; 10-20 parts modified solubilizer; and 0.5-2 parts compounding additives. The modified solubilizer is a graft copolymer prepared by alcoholysis of biomass oil and polyol under alkaline catalyst to obtain an intermediate, followed by ring-opening polymerization of the intermediate with a mixture of propylene oxide and ethylene oxide under closed conditions. The biomass oil is selected from at least one of waste animal and vegetable oils, acidified oils, fatty acid methyl esters, and pine tar. The biomass oil undergoes dehydration and impurity removal treatment before use, and its acid value is controlled to be ≤5 mg KOH / g. The preparation steps of the modified solubilizer include: (1) framework construction: biomass oil and polyol are put into a reaction vessel, and an alkaline catalyst of 0.1wt%-0.3wt% relative to the total mass of biomass oil and polyol is added. The reaction is carried out at 180-220℃ for 1.5-2.5 hours to convert triglycerides into a mixture of monoglycerides and diglycerides containing free hydroxyl groups. Then the temperature is lowered to 110-130℃ for vacuum dehydration; (2) graft modification: an alkaline catalyst or Lewis acid catalyst is added to the mixture obtained in step (1), preferably an alkaline catalyst such as potassium hydroxide, sodium hydroxide, sodium methoxide, or at least one of Lewis acid catalysts such as boron trifluoride or zinc chloride. A mixture of propylene oxide and ethylene oxide is introduced, and the molar ratio of ethylene oxide to propylene oxide is controlled to be to The pressure ring-opening polymerization reaction was carried out under pressure of 0.3-0.5MPa and temperature of 120-140℃ until the pressure in the reactor no longer decreased. After neutralization and filtration, a modified solubilizer with a hydrophilic-lipophilic balance value of 4-7 was obtained. This embodiment provides a biomass alcohol-oil blended fuel, which is a specific implementation of a high methanol ratio formulation. The biomass alcohol-oil blended fuel includes the following raw materials by weight: 50 parts methanol; 40 parts biomass oil; 19 parts modified solubilizer; 1 part compounding agent; wherein, the biomass oil is selected from waste animal and vegetable oils that have been dehydrated and impurity removed and whose acid value is controlled at 4.5 mg KOH / g. The preparation steps of the modified solubilizer include: (1) skeleton construction: waste cooking oil and glycerol as a polyol are put into a reaction vessel, and sodium methoxide at 0.3% relative to the total mass is added as an alkaline catalyst. The alcoholysis reaction is carried out at 220°C for 1.5 hours to prepare an intermediate and dehydrate it; (2) grafting modification: Lewis acid catalyst is added, and a mixture of propylene oxide and ethylene oxide is introduced with a molar ratio of 1:2, that is, ethylene oxide is in excess. The reaction is carried out under the conditions of pressure 0.5 MPa and temperature 140°C to obtain a modified solubilizer with an HLB value of 6.8; In this embodiment, the HLB value is also determined according to the Griffin method, and the formula is: Based on this, by combining the proton peak integral area ratio of the oxyethylene group and the oxypropylene group in the molecular structure of the modified solubilizer with the determination of 1H NMR spectroscopy, the actual molar number of ethylene oxide and propylene oxide groups bonded in the molecular chain can be calculated to accurately determine the hydrophilic groups. and total molecular weight The values ​​are used to ensure the accuracy of the HLB value; in the compound additives, the combustion improver is selected as di-tert-butyl peroxide, and the metal corrosion inhibitor is selected as 2-(2-heptadecene-8-yl-4,5-dihydro-1H-imidazol-1-yl)ethanol, and the two are compounded in a weight ratio of 3:1. In this embodiment, the proportion of combustion improver was specifically increased to compensate for the combustion lag effect caused by the high latent heat of methanol vaporization, compared to 1:1 in Example 1, to ensure the ignition performance of the fuel. At the same time, since the biomass oil content is low, the corrosion risk is relatively reduced, so the proportion of corrosion inhibitor was appropriately reduced. In the preparation method of biomass alcohol-oil blended fuel, the shear rate in step (2) is set to 2800 rpm, and the cyclic shear emulsification in step (3) is carried out for 30 minutes. In this embodiment, for a high proportion of methanol and a formulation system of 50 parts, the proportion of ethylene oxide in the modified solubilizer synthesis is adjusted to a molar ratio of 1:2, which increases the density of hydrophilic segments in the molecular chain and enhances the ability to capture and solubilize polar methanol molecules; at the same time, with a high shear rate of 2800 rpm, the methanol droplets are forced to break into smaller particle sizes and are tightly wrapped by the interfacial film formed by the modified solubilizer. This combination of high hydrophilic density and high shear energy not only overcomes the phase separation tendency caused by high methanol content, but also effectively suppresses the saturated vapor pressure of methanol by utilizing the microemulsion structure, which significantly reduces the safety hazards of fuel in storage and transportation, and reflects the technical advantages brought by the adjustable structure of the modified solubilizer. Furthermore, regarding the lowest calorific value of 7600 kcal / kg measured in this embodiment, the underlying mechanism is as follows: This embodiment selects 50 parts of methanol to maximize the reduction of fuel viscosity and cost. However, since the calorific value of methanol, approximately 4700 kcal / kg, is significantly lower than that of biomass oil, approximately 9000 kcal / kg, a high proportion of methanol will inevitably lead to a decrease in the overall energy density of the blended fuel. Although this ratio sacrifices some calorific value, it gains excellent fluidity and clean combustion. At the same time, for a methanol dispersion of up to 50 parts, a high shear rate of 2800 rpm must be matched, which is the upper limit of the range. This is because a high concentration of dispersion means a sharp increase in the probability of droplet collisions. Only through the strong turbulent energy level provided by high shear force can the droplets be broken down to below the critical particle size that can be completely wrapped by the modified solubilizer, thereby overcoming the kinetic instability caused by the high phase compatibility ratio.

[0016] Example 3: A biomass alcohol-oil blended fuel, wherein in step (1), the polyol is selected from glycerol or pentaerythritol; and in step (2), after the ring-opening polymerization reaction is completed, an organic acid or anhydride is added to esterify and cap the hydroxyl groups at the molecular end, controlling the esterification rate. Steps; This embodiment provides a biomass alcohol-oil blended fuel, which focuses on the construction of a fuel with high calorific value and high stability. The biomass alcohol-oil blended fuel includes the following raw materials in parts by weight: 30 parts methanol; 55 parts biomass oil; 13 parts modified solubilizer; and 2 parts compounding additives. The biomass oil is selected from fatty acid methyl esters that have undergone dehydration and impurity removal treatment and whose acid value is controlled at 2 mgKOH / g. The preparation steps of the modified solubilizer include: (1) skeleton construction: fatty acid methyl ester and pentaerythritol as a polyol are put into the reaction vessel, 0.1% potassium hydroxide is added, and the reaction is carried out at 180°C for 2.5 hours; during this process, the polyhydroxy structure of pentaerythritol provides multi-dimensional growth sites for the grafting reaction; (2) grafting modification: propylene oxide and ethylene oxide are introduced in a molar ratio of 1:1 and reacted under a pressure of 0.3MPa and a temperature of 120°C to obtain a modified solubilizer with an HLB value of 4.2. The HLB value is calculated theoretically by the Griffin method and verified by standard emulsification experiment. The solubilizer is dissolved in the standard oil phase, and water is added dropwise to observe the emulsion phase change point for reverse verification to ensure that it meets the expected hydrophilic and lipophilic properties. In the compound additives, the weight ratio of the combustion aid, 2-ethylhexyl nitrate, and the metal corrosion inhibitor, benzotriazole, is 1:3. This ratio design; The difference from the 1:1 ratio in Example 1 is that the biomass oil content in this example is as high as 55 parts, which has a high cetane number and excellent combustion performance. Therefore, the formulation focuses on inhibiting the oxidative rancidity of biomass oil and its potential corrosion to metal containers. By increasing the proportion of corrosion inhibitor, the long-term storage stability of the fuel is significantly enhanced. In the preparation method of biomass alcohol-oil blended fuel, the oil phase premixing temperature in step (1) is 40℃, the shear rate in step (2) is 1500rpm, and the shearing time in step (3) is 15 minutes. In this embodiment, pentaerythritol is selected as the core skeleton of the modified solubilizer. Its unique neopentyl structure gives the generated graft copolymer a more three-dimensional spatial configuration, which is cross-shaped and can more effectively form a dense protective layer at the oil-in-alcohol and W / O interface. This steric hindrance effect not only maintains the homogeneous stability of the system, but also effectively blocks the intrusion of external moisture, ensuring the combustion stability of the fuel in a humid environment, and demonstrating the synergistic enhancement effect of the modified solubilizer skeleton selection on fuel performance. The structure-activity relationship of the highest calorific value of 8800 kcal / kg measured in this embodiment is due to the selection of a ratio of 30 parts methanol to 55 parts biomass oil. This ratio preserves the high energy density characteristics of biomass oil to the greatest extent, making it suitable for scenarios with stringent power output requirements. Matching this, the shear rate is set to the lower limit of 1500 rpm. This is because, under low dispersed phase and methanol concentration, the system requires less emulsification work, and a lower shear energy is sufficient to achieve uniform distribution of the dispersed phase. Excessive shear rate not only increases energy consumption but may also lead to methanol volatilization loss due to temperature rise. This selection of process parameters of low alcohol, high oil, and low shear establishes the optimal energy efficiency solution under the pursuit of high calorific value.

[0017] Example 4: A biomass alcohol-oil blended fuel, wherein in step (1) the polyol is selected from glycerol or pentaerythritol; after the ring-opening polymerization reaction is completed in step (2), an acidic catalyst and organic acid or an acid anhydride are added after neutralizing the alkaline catalyst, and the hydroxyl groups at the end of the molecule are partially esterified and capped under heating conditions. This embodiment provides a biomass-ethanol-oil blended fuel, which is optimized for adaptability to low-quality biomass feedstocks. The biomass-ethanol-oil blended fuel comprises the following raw materials in parts by weight: 35 parts methanol; 45 parts biomass oil; 18 parts modified solubilizer; and 2 parts compounding additives. The biomass oil is selected from materials that have undergone dehydration and impurity removal treatment and whose acid value is controlled within a certain range. The preparation steps of the modified solubilizer of pine tar after the ring-opening polymerization reaction in step (2) also include the step of adding acetic anhydride to partially esterify and cap the hydroxyl groups at the end of the molecule, and finally obtain a modified solubilizer with an HLB value of 5.0. The compounding additives and preparation process are as described in Example 1. In step (2), a pipeline shear pump is used as a shearing device, and the number of times the material circulates in the pipeline is set to 5-10 times to ensure the instantaneous shearing uniformity of the high viscosity oil phase. This embodiment innovatively introduces an end-capping step in the preparation of modified solubilizers for pine tar, a high-viscosity and complex biomass oil source. Esterification end-capping with acetic anhydride eliminates residual polar hydroxyl groups at the molecular ends and reduces non-specific hydrogen bonding between molecules, thereby significantly improving the dispersibility and wetting ability of the modified solubilizer in the complex matrix of pine tar. At the same time, the continuous operation mode of the pipeline shear pump ensures instantaneous and thorough mixing of the high-viscosity oil phase and the low-viscosity methanol phase, avoiding local overheating or uneven mixing. This verifies the adaptability of the technical solution of this invention to inferior biomass feedstocks and the robustness of the process.

[0018] Example 5: A biomass alcohol-oil blended fuel comprises the following raw materials in parts by weight: 30-50 parts methanol; 35-55 parts biomass oil; 10-20 parts modified solubilizer; and 0.5-2 parts compounding additives. The modified solubilizer is a graft copolymer prepared by alcoholysis reaction of biomass oil and polyol under alkaline catalyst to obtain an intermediate, and then by ring-opening polymerization reaction of the intermediate with a mixture of propylene oxide and ethylene oxide under closed conditions. This embodiment provides a biomass alcohol-oil blended fuel, aiming to investigate its broad applicability under composite oil sources. The biomass alcohol-oil blended fuel includes the following raw materials by weight: 45 parts methanol; 40 parts biomass oil; 14.5 parts modified solubilizer; and 0.5 parts compounding additive. Among them, the biomass oil is a blended oil of acidified oil and fatty acid methyl ester at a ratio of 1:1, with the acid value controlled at 4 mgKOH / g. In the preparation of the modified solubilizer, glycerol is used in step (1) and the reaction temperature is 210℃; in step (2), the molar ratio of ethylene oxide to propylene oxide is 1:1.2, the reaction temperature is 135℃, and the HLB value is controlled at 6.0. In the compound additives, 2-ethylhexyl nitrate, combustion improver and benzotriazole, metal corrosion inhibitor are compounded in a weight ratio of 2:1. The internal ratio is set in order to ensure the full combustion of the compound oil source. Acidified oil has a complex composition and its combustion characteristics are not as good as pure methyl ester. The appropriate amount of corrosion inhibitor is used to protect the equipment. This reflects the strategy of achieving performance balance by adjusting the internal ratio at a low addition amount of 0.5 parts. The preparation method of biomass alcohol oil mixed fuel strictly controls the injection flow rate of methanol in step (2) and is matched with a shear rate of 2500 rpm. The experiment in this embodiment shows that the hydrogen bonding force formed between the polyether segments in the modified solubilizer and the methanol hydroxyl groups is sufficient to resist the interfacial tension fluctuations caused by different oil phase components, acidified oil and methyl ester. When the fuel prepared in this way is burned, because the boiling point of methanol in the microemulsion droplets is much lower than that of the outer biomass oil, the methanol rapidly vaporizes and expands after heating, producing a strong micro-explosion effect, which breaks the oil droplets into finer atomized particles, significantly improving combustion efficiency and reducing carbon deposits. This reflects the innovative mechanism of the present invention to achieve chemical solubilization and physical micro-explosion through molecular structure design.

[0019] Comparative Example 1: This comparative example provides a blended fuel with the same raw material ratio as Example 1, except that no modified solubilizer is added, and methanol and biomass oil are mixed by simple mechanical stirring. This comparative example aims to verify the necessity of the modified solubilizer in constructing a homogeneous structure in the system, and serves as a blank control group.

[0020] Comparative Example 2: This comparative example provides a blended fuel with the same raw material ratio as Example 1, except that a commercially available physical emulsifier, a compound of Span-80, sorbitan monooleate, and Tween-80, polysorbate-80 at an HLB value of 5.5, is used instead of the modified solubilizer. This comparative example aims to verify the advantages of the graft copolymer prepared by chemical bonding in this invention over traditional physically compounded emulsifiers in terms of interfacial film strength and stability.

[0021] Comparative Example 3: This comparative example provides a mixed fuel with the same raw material ratio as Example 1. The difference is that in the preparation process of the modified solubilizer, only ethylene oxide is introduced for polymerization, and propylene oxide is not introduced to prepare a simple polyethylene glycol graft. This comparative example aims to verify the key role of the introduction of propylene oxide segments in regulating molecular spatial configuration, providing steric hindrance, and balancing hydrophilicity and lipophilicity.

[0022] Verification experiment: To verify the performance of the biomass alcohol-oil blended fuel of the present invention, the fuels prepared in Examples 1-5 and Comparative Examples 1-3 were subjected to performance tests.

[0023] Testing standards: Phase stability: The time (in days) for stratification to occur when the system is left to stand at 25°C, used to characterize the thermodynamic stability of the system; Lower heating value: Determined according to GB / T384 "Determination of calorific value of petroleum products", kcal / kg, used to evaluate the energy density of fuel.

[0024] Flash point: Determined according to GB / T261 "Determination of flash point - Binsky-Martin closed cup method", ℃, used to characterize the volatility inhibition effect and safety; Copper strip corrosion: Tested according to GB / T5096 "Petroleum Products Copper Strip Corrosion Test Method", 50℃, 3h, used to evaluate the corrosiveness of fuel to metal parts.

[0025] Each example and comparative sample was prepared independently three times, and the average value was taken as the final test result. For the phase stability test, the sample was placed in a sealed transparent glass bottle and observed at regular intervals every day, and the time when the first obvious phase separation interface appeared was recorded. For the flash point test, the heating rate was strictly controlled to ensure the accuracy of the data.

[0026] Table 1. Performance test results of the examples and comparative examples. As shown in Table 1, the modified solubilizer prepared by the present invention through a specific process exhibits significant technical advantages in constructing a homogeneous biomass alcohol-oil system; the specific analysis is as follows: The structure-activity relationship analysis of stability and molecular structure compared with Examples 1-5 and Comparative Examples 1 and 2 shows that the fuel systems with the modified solubilizer of this invention have a phase stability of over 160 days, which is far superior to physical mixing. Comparative Example 1 shows immediate stratification and is compounded with traditional emulsifiers, while Comparative Example 2 shows 5 days. This indicates that the solubilizer constructed by the two-step alcoholysis-grafting method of this invention retains long biomass oil chains in its molecular structure, which have excellent compatibility with the base oil phase. The grafted polyether segments tightly anchor methanol molecules through multi-point hydrogen bonding. The interfacial film strength formed by this chemically bonded amphiphilic structure is much higher than that of the physical adsorption film of traditional small molecule emulsifiers, effectively resisting droplet coalescence caused by Brownian motion.

[0027] Comparing the steric hindrance effect of propylene oxide segments with data from Example 1 and Comparative Example 3, it was found that the solubilizer with only ethylene oxide segments introduced, Comparative Example 3, had significantly lower stability (>180 days, 38°C) than Example 1, which simultaneously introduced propylene oxide (PO) and EO (>180 days, 38°C). The mechanism is that the EO segments alone have high crystallinity and poor flexibility, making it difficult to form an effective steric barrier at the oil-ethanol interface. The introduction of the methyl group on the side of the PO segments increases the disorder and steric hindrance of the molecular chains, causing the solubilizer molecules to have a more extended conformation at the interface, forming a thicker solvation layer, which more effectively prevents the escape of methanol molecules and the coalescence of droplets. The flash point enhancement and safety mechanism of Examples 1-5 (35-42℃) are significantly higher than those of pure methanol (approximately 11℃) and Comparative Example 2 (18℃). This confirms that a strong hydrogen bond network is formed between the ether oxygen atoms in the modified solubilizer and the methanol hydroxyl groups. This intermolecular force significantly reduces the saturated vapor pressure of methanol. In particular, Example 3 uses a pentaerythritol framework, whose highly branched structure further enhances the encapsulation effect on methanol, thus achieving the highest flash point of 42℃, verifying the synergistic contribution of the framework structure to safety.

[0028] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A biomass alcohol-oil blended fuel, characterized in that, Including the following parts by weight of raw materials: 30-50 parts methanol; 35-55 parts of biomass oil; 10-20 parts of modified solubilizer; Compound adjuvant 0.5-2 parts; The modified solubilizer is a polyether ester derivative with a hydrophilic-lipophilic balance value of 4-7, obtained by alcoholysis reaction of biomass oil and polyol under the action of alkaline catalyst, and then by ring-opening polymerization of the intermediate with a mixture of propylene oxide and ethylene oxide under closed conditions.

2. The biomass alcohol-oil blended fuel according to claim 1, characterized in that, The biomass oil is selected from at least one of waste animal and vegetable oils, acidified oils, fatty acid methyl esters, and pine tar; The biomass oil undergoes dehydration and impurity removal treatment before use, and its acid value is controlled to be ≤5mgKOH / g.

3. The biomass alcohol-oil blended fuel according to claim 1, characterized in that, The preparation steps of the modified solubilizer include: (1) Framework construction: Biomass oil and polyol are put into a reactor, and alkaline catalyst of 0.1wt%-0.3wt% relative to the total mass of biomass oil and polyol is added. The reaction is carried out at 180-220℃ for 1.5-2.5 hours to convert triglycerides into a mixture of monoglycerides and diglycerides containing free hydroxyl groups. Then the temperature is lowered to 110-130℃ for vacuum dehydration. (2) Grafting modification: Add an alkaline catalyst or Lewis acid catalyst to the mixture obtained in step (1), preferably an alkaline catalyst such as potassium hydroxide, sodium hydroxide, or sodium methoxide, or at least one of a Lewis acid catalyst such as boron trifluoride or zinc chloride. Introduce a mixture of propylene oxide and ethylene oxide, controlling the molar ratio of ethylene oxide to propylene oxide to be [value missing]. to The reaction was carried out under pressure of 0.3-0.5 MPa and temperature of 120-140℃ until the pressure in the reactor stopped decreasing. After neutralization and filtration, a modified solubilizer with a hydrophilic-lipophilic balance value of 4-7 was obtained.

4. The biomass alcohol-oil blended fuel according to claim 3, characterized in that, The polyol mentioned in step (1) is selected from glycerol or pentaerythritol; After the ring-opening polymerization reaction described in step (2) is completed, the process also includes adding an acidic catalyst and an organic acid, or directly adding an acid anhydride, to partially esterify and cap the hydroxyl groups at the end of the molecule under heating conditions after neutralizing the alkaline catalyst.

5. The biomass alcohol-oil blended fuel according to claim 1, characterized in that, The compound additives include combustion improvers and metal corrosion inhibitors; The combustion improver is selected from one or a combination of isooctyl nitrate, 2-ethylhexyl nitrate, and di-tert-butyl peroxide. The metal corrosion inhibitor is selected from one or a combination of benzotriazole and 2-[2-(8-heptadecenyl)-4,5-dihydro-1H-imidazol-1-yl]ethanol.

6. A method for preparing a biomass alcohol-oil blended fuel according to any one of claims 1-5, characterized in that, Includes the following steps: (1) Oil phase premixing: Biomass oil and modified solubilizer are added to a mixing tank according to the weight parts described in claim 1, and mixed at low speed under the conditions of temperature 25-40℃ and stirring speed 300-500rpm to form a uniform oil phase base. (2) Alcohol phase injection: Turn on the shearing equipment and set the shearing rate to 1500-2800 rpm. Slowly inject methanol into the oil phase base under high-speed shearing to perform preliminary emulsification using mechanical shearing force. (3) Homogenization treatment: After the methanol injection is completed, add compound additives, keep the shear rate unchanged, and continue to perform cyclic shear emulsification for 15-30 minutes until the system is homogeneous and transparent or semi-transparent, thus obtaining biomass alcohol oil compound fuel.

7. The method for preparing biomass alcohol-oil blended fuel according to claim 6, characterized in that, In step (2), the methanol injection process needs to control the flow rate to prevent excessive local methanol concentration from causing demulsification; The shearing equipment is a high-shear emulsifier or a pipeline shearing pump.

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