A method for preparing a green, low-carbon, and high-efficiency modified fuel for alcohol-hydrogen engines.

Abstract

This invention belongs to the field of environmentally friendly fuel technology, specifically relating to a method for preparing a green, low-carbon, and highly efficient modified fuel for alcohol-hydrogen engines. This invention comprehensively improves fuel performance through a progressive synergistic architecture of a bio-methanol platform – an oxygen-containing combustion-promoting system – a stability barrier – and a low-energy-consumption blending path. Using bio-methanol as a base, it optimizes combustion by compounding with oxygen-containing components such as 2-MTHF and DMM / MF, achieving rapid ignition, emission reduction, and noise reduction. Phase behavior is regulated by isobutanol and polyether-modified silicon, achieving a reversible and stable phase without the need for high-HLB surfactants, preventing deposition and gas lock. A four-fold protective barrier is constructed using GMO and fluorinated silica polyethers, combined with antioxidant synergy to achieve corrosion resistance and aging resistance. The process adopts a sequential design of front-end purification – mid-stage two-phase construction – and end-stage static mixing, achieving low-energy homogenization and ensuring storage, transportation, and operational stability.

Description

Technical Field

[0001] This invention belongs to the field of environmentally friendly fuel technology, specifically relating to a method for preparing a green, low-carbon, and highly efficient modified fuel for alcohol-hydrogen engines. Background Technology

[0002] Methanol-hydrogen engine technology has received widespread attention in recent years as an important pathway to achieving low-carbon transportation. Methanol fuel produced from biomass feedstock is considered an ideal energy carrier due to its renewable characteristics. However, both traditional fossil-based methanol and biomass methanol face a series of common and unique technical challenges in practical engine applications. Regarding fuel characteristics, methanol itself suffers from low energy density, high latent heat of vaporization, and insufficient vapor pressure at room temperature, directly affecting the engine's cold-start performance and power output; its slow flame propagation speed also limits further improvements in thermal efficiency. In terms of stability and compatibility, methanol's strong polarity and hygroscopicity easily lead to compatibility issues with various non-metallic materials (such as rubber seals and plastic components), resulting in swelling, aging, and decreased fuel system reliability. Simultaneously, impurities in the fuel, such as moisture, trace aldehydes, organic acids, and metal ions, can induce phase separation and decreased oxidation stability during storage and transportation, and also cause corrosion, deposition, and wear in the combustion chamber and fuel supply system. In existing technologies, although there have been several attempts to improve certain performance characteristics of methanol fuel by adding oxygen-containing components (such as ethers and esters) or functional additives, these approaches often focus on improving a single performance indicator, such as improving combustion efficiency or inhibiting corrosion, lacking a systematic and synergistic design for fuel purification, combustion optimization, material compatibility, and long-term stability. Furthermore, many modification schemes rely on complex refining processes or high-cost specialized additives, resulting in insufficient overall economic viability and potential for large-scale application. Summary of the Invention

[0003] In view of the shortcomings of the prior art, the purpose of this invention is to provide a method for preparing green, low-carbon, and efficient modified fuel for alcohol-hydrogen engines.

[0004] The technical effects described in this invention are achieved through the following technical solution: a method for preparing a green, low-carbon, and highly efficient modified fuel for an alcohol-hydrogen engine, specifically including the following steps:

[0005] S1: Crude bio-methanol was placed in a stirred tank and filtered through a 0.45μm PP filter cartridge. Then, 3A molecular sieve was added, and the mixture was stirred and adsorbed at 25°C and 450rpm for 3 hours. Then, online vacuum distillation was carried out. The methanol fraction was collected under vacuum conditions of 62-65°C at the top of the column, 68-70°C at the bottom of the column, and -0.06MPa until the water content was ≤0.1wt%, thus obtaining refined methanol.

[0006] S2: Add a 10wt% sodium bisulfite-methanol solution dropwise to the purified methanol from step S1, and react at 20–25°C and 300 rpm for 30–60 min to complex trace amounts of formaldehyde / acetaldehyde; add 0.2% activated carbon for adsorption for 40–60 min, filter through a 0.2 μm ceramic membrane; add iminodiacetic acid chelating resin for recycling treatment to obtain pretreated bio-methanol;

[0007] S3: Add 2-methyltetrahydrofuran, methyl formate, glyceryl monooleate, trifluoropropyl silicone oil and polyether-modified organosilicon sequentially to a stirred tank, and stir at 25-30℃ and 500-600 rpm. After each component is added, stir at a constant temperature for 10-20 min. After mixing, raise the temperature to 35℃ and pre-disperse at 1200 rpm for 5 min to obtain mother liquor A.

[0008] S4: Add dimethoxymethane, isobutanol, and oleyl amine sequentially to a container, and stir at 40°C and 500 rpm for 10–20 min. Dissolve methylbenzotriazole in dimethoxymethane to prepare a 2–5 wt% mother liquor, and then slowly add it to the container. Then add propyl gallate and tocopherol, and stir at 35°C and 400 rpm for 10–20 min to obtain mother liquor B.

[0009] S5: Slowly pump the mother liquor B from step S4 into the mother liquor A from step S3, maintain at 32-35°C; mix at 1500-2000 rpm under high shear for 8-12 minutes; degas under vacuum for 10 minutes; let stand for 30-60 minutes; and filter at 0.2 μm to obtain the concentrate.

[0010] S6: Add deionized water to the pretreated bio-methanol from step S2 until the target water content is 1-1.5 wt%. Stir at 25°C and 400 rpm for 10-20 min. Slowly add the concentrate from step S5. Stir at 25-28°C and 600-800 rpm for 20 min. Degas under vacuum for 10 min. Mix statically. Filter with a 0.2 μm filter. Let stand for 60 min to defoam, and obtain green, low-carbon, and high-efficiency modified fuel.

[0011] Preferably, in step S1, the crude bio-methanol is prepared by gasification synthesis using at least one of biological waste straw, forestry residue and organic waste as raw materials.

[0012] Preferably, in step S1, the amount of the 3A molecular sieve added is 1.5-2% based on the mass fraction of crude bio-methanol;

[0013] Preferably, in step S2, the amount of sodium bisulfite-methanol solution added is 1% by mass fraction of purified methanol;

[0014] Preferably, in step S2, the recycling parameters of the iminodiacetic acid chelating resin are: 5-10 wt% aqueous methanol as the working medium, 2-5 BV / h recycling until the output metal is <0.5 ppm;

[0015] Preferably, in step S2, the amount of activated carbon added is calculated as the mass fraction of refined methanol;

[0016] Preferably, in step S3, the mass ratio of 2-methyltetrahydrofuran, methyl formate, glyceryl monooleate, trifluoropropyl silicone oil, and polyether-modified organosilicon is 0.6–0.85:0.14–0.25:0.32–0.54:0.06–0.12:0.08–0.14.

[0017] Preferably, in step S4, the mass ratio of dimethoxymethane, isobutanol, oleyl amine, methylbenzotriazole, propyl gallate, and tocopherol is 0.4–0.55:0.25–0.32:0.06–0.1:0.001–0.002:0.04–0.06:0.049–0.068.

[0018] Preferably, in step S5, the mass ratio of mother liquor B to mother liquor A is 0.8-1.1:1.2-1.9;

[0019] Preferably, in step S6, the amount of the concentrated solution added is 2-3% based on the mass fraction of refined methanol;

[0020] Preferably, in step S6, the static mixing parameters are as follows: the material is fed into the static mixer via a gear pump of sections 6 to 12, with Re ≥ 5000 and linear velocity of 1.5 to 2.5 m / s controlled; an online turbidity detector is installed at the outlet, and Δ turbidity < 5 NTU is used as the threshold for completion of mixing.

[0021] The beneficial effects of this invention are as follows:

[0022] Compared with existing technologies, this invention achieves a comprehensive improvement in fuel combustion performance, stability, and durability through a progressive synergistic architecture that constructs a bio-methanol platform, an oxygen-containing combustion-promoting system, material and chemical stability barriers, and a low-energy-consumption blending path. Regarding combustion performance, based on bio-derived methanol, it synergistically introduces a moderately volatile, high-energy-density oxygen-containing modifier (2-methyltetrahydrofuran / 2-MTHF) and a low-boiling-point, lightweight oxygen-containing component (dimethoxymethane / DMM, methyl formate / MF), achieving dual-end optimization of evaporation curves and ignition delay characteristics. The high-boiling-point oxygen-containing component improves volumetric energy density and atomization performance, while the lightweight oxygen-containing component enhances low-temperature activity and lean-flame stability. With the synergy of trace amounts of process water, both further broaden the flammability limit and suppress peak combustion temperature, thereby improving lean-flame stability and combustion completeness. Engine performance is characterized by rapid ignition, reduced cycle fluctuations, and an expanded lean-flame boundary. In terms of exhaust emissions, it achieves reductions in carbon monoxide and unburned hydrocarbons and effectively suppresses nitrogen oxide formation. In terms of interface and phase behavior regulation, a light alcohol co-solvent (isobutanol) and a low-molecular-weight oxygen-containing component synergistically regulate the polar gradient and interfacial free energy, suppressing the microemulsion tendency induced by the aqueous phase in the polar matrix. This achieves a reversible and clean phase stability window without relying on high affinity-reluctance balance (HLB) surfactants. This reversible stability is crucial for engine operation and storage: under temperature and shear disturbances, the system can quickly recover to a homogeneous phase, avoiding deposition and pressure differential problems in the injection system and filters. Simultaneously, polyether-modified silicone effectively breaks down microbubbles introduced during mixing and transportation at extremely low addition levels, reducing gas resistance and cavitation risks, without introducing additional aqueous phase or surface-active residues, thus preventing secondary emulsification and deposition at the source. Material compatibility and corrosion protection are achieved through a synergistic four-barrier system: boundary lubrication film, sealing against swelling, metal surface passivation, and free radical chain termination. Bio-based fatty acid esters (glycerol monooleate / GMO) form a polar adsorption layer on the metal friction pair, maintaining boundary lubrication and the cleanliness of the spray system. Fluorinated silicone polyethers construct a low-surface-energy fluorine-rich layer on the elastomer surface, inhibiting the penetration of polar media and volume expansion. Oil-based primary amines form a hydrophobic protective film on the iron-based material surface through directional adsorption, inhibiting electrochemical corrosion. Methylbenzotriazole forms a stable complex layer on the copper alloy surface, blocking the oxidation chain reaction involving metal ions. These interfacial chemistry and surface passivation mechanisms, synergistically with the free radical capture and peroxide decomposition functions of phenols and gallic esters, construct a closed-loop anti-aging mechanism of initiation passivation, process interception, and terminal termination, significantly delaying color deepening, acid value and peroxide value increases, and improving stability under storage, transportation, and high / low temperature cycling conditions.

[0023] In terms of raw material and process synergy, a sequential design is adopted. The front end uses selective complexation, adsorption, and demetallization to effectively remove active sites and catalytic centers that trigger self-oxidation and corrosion, creating controllable load conditions for subsequent antioxidant and metal passivation. The middle section adopts a two-phase construction strategy, integrating hydrophobic functions such as lubrication, sealing, and defoaming into a low-polarity phase, and integrating polar functions such as combustion promotion and antioxidant into a high-polarity phase. Homogenization is achieved under mild energy input, ensuring that each functional component is fully dissolved in the affinity phase without interfering with each other. Dissolved oxygen and micro-agglomerates are eliminated in advance through degassing and fine filtration. The end section adopts a static mixing path with controllable turbulence superimposed with laminar flow broadening to achieve homogenization of the entire system. This avoids the structural performance loss of low-viscosity systems caused by high-pressure homogenization and maximizes the suppression of secondary oxidation and bubble regeneration in a closed, nitrogen-sealed environment. Each process node is closely linked: the micro-hydration environment improves complexation and demetallization efficiency without introducing the risk of final phase separation; the dispersion-degassing-final filtration process ensures the high efficiency of the defoamer without disrupting the phase balance; short-term static settling after static mixing promotes the reorganization of the system's microstructure, and combined with online monitoring of conductivity and turbidity, clear release standards are established. Attached Figure Description

[0024] Figure 1 These are isothermal evaporation loss diagrams from combustion and volatilization tests of modified fuels in Embodiment 1 and Comparative Examples 1-4 of the present invention.

[0025] Figure 2 These are volumetric calorific value diagrams from combustion and volatilization tests of the modified fuels in Embodiment 1 and Comparative Examples 1-4 of the present invention;

[0026] Figure 3 This is a graph showing the change rate of copper sheet mass in the corrosion test of modified fuels in Example 1 and Comparative Examples 1-4 of this invention;

[0027] Figure 4 These are the oxidation induction period results in the stability and anti-aging tests of the modified fuels in Example 1 and Comparative Examples 1-4 of this invention;

[0028] Figure 5 This is a graph showing the acid value growth rate in the stability and anti-aging tests of modified fuels in Embodiment 1 and Comparative Examples 1-4 of the present invention. Detailed Implementation

[0029] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Unless otherwise specified, the raw materials involved in the present invention are all purchased through conventional commercial channels. Experimental methods without specific conditions are conventional methods and conditions well known in the art, or according to the conditions recommended by the instrument manufacturer.

[0030] Example 1: A method for preparing a green, low-carbon, and high-efficiency modified fuel for an alcohol-hydrogen engine, specifically including the following steps:

[0031] S1: 1000g of crude bio-methanol was placed in a stirred tank and filtered through a 0.45μm PP filter. Then, 18g of 3A molecular sieve was added, and the mixture was stirred and adsorbed at 25°C and 450rpm for 3h. Then, online vacuum distillation was carried out. The methanol fraction was collected under vacuum conditions of 63°C at the top of the column, 69°C at the bottom of the column, and -0.06MPa until the water content was ≤0.1wt%, thus obtaining refined methanol.

[0032] S2: Add 10g of 10wt% sodium bisulfite-methanol solution dropwise to 1000g of purified methanol from step S1, and react at 23°C and 300rpm for 50min to complex trace amounts of formaldehyde / acetaldehyde; add 2g of activated carbon for adsorption for 50min, and filter through a 0.2μm ceramic membrane; add 2L of iminodiacetic acid chelating resin for circulation treatment, using 8wt% aqueous methanol as the working medium, and circulate at 3BV / h until the effluent metal is <0.5ppm to obtain pretreated bio-methanol;

[0033] S3: Add 7g of 2-methyltetrahydrofuran, 2g of methyl formate, 4g of glyceryl monooleate, 1g of trifluoropropyl silicone oil and 1g of polyether-modified organosilicon to the stirred tank in sequence, and stir at 28℃ and 550rpm. After each component is added, stir at a constant temperature for 15min. After mixing, raise the temperature to 35℃ and pre-disperse at 1200rpm for 5min to obtain mother liquor A.

[0034] S4: Add 4.6g of dimethoxymethane, 3g of isobutanol and 0.9g of oleyl amine to a container in sequence, stir at 40℃ and 500rpm for 15min, dissolve 0.016g of methylbenzotriazole in 0.4g of dimethoxymethane to prepare a 4wt% mother liquor and slowly add it; then add 0.5g of propyl gallate and 0.584g of tocopherol, stir at 35℃ and 400rpm for 15min to obtain mother liquor B;

[0035] S5: Slowly pump 10g of mother liquor B from step S4 into 15g of mother liquor A from step S3, maintain 33°C; mix at 1800rpm high shear for 10min; degas under vacuum for 10min, let stand for 50min; filter at 0.2μm to obtain concentrated solution;

[0036] S6: Add deionized water to the pretreated bio-methanol from step S2 until the target water content is 1.2 wt%. Stir at 25°C and 400 rpm for 15 min. Slowly add 25 g of the concentrate from step S5. Stir at 26°C and 700 rpm for 20 min. Degas under vacuum for 10 min. The material is fed into a static mixer via a 10-section gear pump, with Re ≥ 5000 and linear velocity 2 m / s controlled. An online turbidity detector is installed at the outlet, with Δ turbidity < 5 NTU as the mixing completion threshold. Filter with a 0.2 μm filter. Let stand for 60 min to defoam, obtaining green, low-carbon, and high-efficiency modified fuel.

[0037] Example 2: A method for preparing a green, low-carbon, and high-efficiency modified fuel for an alcohol-hydrogen engine, specifically including the following steps:

[0038] S1: 1000g of crude bio-methanol was placed in a stirred tank and filtered through a 0.45μm PP filter. Then, 15g of 3A molecular sieve was added, and the mixture was stirred and adsorbed at 25°C and 450rpm for 3h. Then, online vacuum distillation was carried out. The methanol fraction was collected under vacuum conditions of 62°C at the top of the column, 68°C at the bottom of the column, and -0.06MPa until the water content was ≤0.1wt%, thus obtaining refined methanol.

[0039] S2: Add 10g of 10wt% sodium bisulfite-methanol solution dropwise to 1000g of purified methanol from step S1, and react at 20°C and 300rpm for 30min to complex trace amounts of formaldehyde / acetaldehyde; add 2g of activated carbon for adsorption for 40min, and filter through a 0.2μm ceramic membrane; add 2L of iminodiacetic acid chelating resin for circulation treatment, using 5wt% aqueous methanol as the working medium, and circulate at 2BV / h until the effluent metal is <0.5ppm to obtain pretreated bio-methanol;

[0040] S3: Add 6g of 2-methyltetrahydrofuran, 1.4g of methyl formate, 3.2g of glyceryl monooleate, 0.6g of trifluoropropyl silicone oil and 0.8g of polyether-modified organosilicon to a stirred tank in sequence. Stir at 25℃ and 500rpm, and stir at a constant temperature for 10min after each addition of a component. After mixing, raise the temperature to 35℃ and pre-disperse at 1200rpm for 5min to obtain mother liquor A.

[0041] S4: Add 3.5g dimethoxymethane, 2.5g isobutanol and 0.6g oleyl amine to a container in sequence, stir at 40℃ and 500rpm for 10min, dissolve 0.01g methylbenzotriazole in 0.5g dimethoxymethane to prepare a 2wt% mother liquor and slowly add it; then add 0.4g propyl gallate and 0.49g tocopherol, stir at 35℃ and 400rpm for 10min to obtain mother liquor B;

[0042] S5: Slowly pump 8g of mother liquor B from step S4 into 12g of mother liquor A from step S3, maintain 32°C; mix at 1500rpm high shear for 12min; degas under vacuum for 10min, let stand for 30min; filter at 0.2μm to obtain concentrated solution;

[0043] S6: Add deionized water to the pretreated bio-methanol from step S2 until the target water content is 1wt%. Stir at 25°C and 400 rpm for 10 min. Slowly add 20 g of the concentrate from step S5. Stir at 25°C and 600 rpm for 20 min. Degas under vacuum for 10 min. The material is fed into a static mixer via a 12-section gear pump, with Re ≥ 5000 and linear velocity 2.5 m / s. An online turbidity detector is installed at the outlet, with Δturbidity < 5 NTU as the threshold for completion of mixing. Filter with a 0.2 μm filter. Let stand for 60 min to defoam, obtaining green, low-carbon, and high-efficiency modified fuel.

[0044] Example 3: A method for preparing a green, low-carbon, and high-efficiency modified fuel for an alcohol-hydrogen engine, specifically including the following steps:

[0045] S1: Place 1000g of crude bio-methanol in a stirred tank, filter it through a 0.45μm PP filter, add 20g of 3A molecular sieve, and stir and adsorb at 25°C and 450rpm for 3h; then perform online vacuum distillation, collect the methanol fraction under the conditions of 65°C at the top of the column, 70°C at the bottom of the column, and -0.06MPa vacuum, until the water content is ≤0.1wt%, to obtain refined methanol;

[0046] S2: Add 10g of 10wt% sodium bisulfite-methanol solution dropwise to the purified methanol from step S1, and react at 25°C and 300rpm for 60min to complex trace amounts of formaldehyde / acetaldehyde; add 2g of activated carbon for adsorption for 60min, and filter through a 0.2μm ceramic membrane; add 2L of iminodiacetic acid chelating resin for circulation treatment, using 10wt% aqueous methanol as the working medium, and circulate at 5BV / h until the effluent metal is <0.5ppm to obtain pretreated bio-methanol;

[0047] S3: Add 8.5g of 2-methyltetrahydrofuran, 2.5g of methyl formate, 5.4g of glyceryl monooleate, 1.2g of trifluoropropyl silicone oil and 1.4g of polyether-modified organosilicon to a stirred tank in sequence. Stir at 30℃ and 600rpm, and stir at a constant temperature for 20min after each addition of a component. After mixing, raise the temperature to 35℃ and pre-disperse at high shear at 1200rpm for 5min to obtain mother liquor A.

[0048] S4: Add 5.1g dimethoxymethane, 3.2g isobutanol and 1g oleyl amine to a container in sequence, stir at 40℃ and 500rpm for 20min, dissolve 0.02g methylbenzotriazole in 0.4g dimethoxymethane to prepare a 5wt% mother liquor and slowly add it; then add 0.6g propyl gallate and 0.68g tocopherol, stir at 35℃ and 400rpm for 20min to obtain mother liquor B;

[0049] S5: Slowly pump 11g of mother liquor B from step S4 into 19g of mother liquor A from step S3, maintaining a temperature of 35°C; mix at 2000rpm under high shear for 8min; degas under vacuum for 10min; let stand for 60min; and filter through a 0.2μm filter to obtain a concentrated solution.

[0050] S6: Add deionized water to the pretreated bio-methanol from step S2 until the target water content is 1.5 wt%. Stir at 25°C and 400 rpm for 20 min. Slowly add 30 g of the concentrate from step S5. Stir at 28°C and 800 rpm for 20 min. Degas under vacuum for 10 min. The material is fed into a static mixer via a 6-section gear pump, with Re ≥ 5000 and linear velocity 1.5 m / s. An online turbidity detector is installed at the outlet, and Δturbidity < 5 NTU is used as the mixing completion threshold. Filter with a 0.2 μm filter. Let stand for 60 min to defoam, and obtain green, low-carbon, and high-efficiency modified fuel.

[0051] Comparative Example 1: The raw materials and processes of Comparative Example 1 are basically the same as those of Example 1. The main difference is that Comparative Example 1 does not perform front-end trace impurity and metal removal treatment, that is, it does not perform step S2; the rest of the process and parameters are the same.

[0052] Comparative Example 2: The raw materials and processes of Comparative Example 2 are basically the same as those of Example 1. The main difference is that in Comparative Example 2, isobutanol is replaced with an equal mass of high HLB nonionic surfactant ethoxylated castor oil to keep the total oxygen content and total mass unchanged; the rest of the process and parameters are kept the same.

[0053] Comparative Example 3: The raw materials and processes of Comparative Example 3 are basically the same as those of Example 1. The main difference is that in Comparative Example 3, oil-based primary amine and methylbenzotriazole are not added in step S4. In step S4, the remaining volatile oxygen-containing components are increased proportionally to keep the total mass of mother liquor B unchanged. The rest of the process and parameters are kept the same.

[0054] Comparative Example 4: The raw materials and processes of Comparative Example 4 are basically the same as those of Example 1. The main difference is that in Comparative Example 4, step S3 does not involve high-shear pre-dispersion, and the mixture is obtained only under conventional stirring conditions; in S5, the high-shear, vacuum degassing, and 0.2μm fine filtration steps after pumping B into A are eliminated, and conventional stirring and mixing are used instead; in the final mixing stage of S6, the static mixer is abandoned, and a single 30MPa high-pressure homogenization is used to complete the mixing; the rest of the process and parameters remain the same.

[0055] Performance testing: The modified fuels prepared by the processes of Examples 1-3 and Comparative Examples 1-4 were tested. The kinematic viscosity of the modified fuels was tested according to GB / T265-1988, the flash point of the modified fuels was tested according to GB / T21789-2008, and the color was observed and recorded. The acid value of the modified fuels was tested according to GB / T 7304-2014. The results are shown in Table 1 below.

[0056] Table 1. Performance test results of modified fuels in the examples and comparative examples

[0057]

[0058] Based on the results in Table 1, the modified fuel of this invention exhibits high uniformity and stability in its basic physicochemical properties, with its kinematic viscosity concentrated between 0.58 and 0.66 mm. 2Within a narrow range of / s, the fuel exhibited a clear appearance and low acid value; this indicates that the deep purification at the front end and the degassing and fine filtration process after two-phase construction effectively removed impurities and oxidizable precursors; the synergistic effect of the formulation and process established a solid foundation for the initial stability of the fuel. Comparative Example 1, which omitted the front-end purification step, still showed similar kinematic viscosity and flash point to the example, indicating that the main physical properties of the fuel matrix and light-end components were not directly altered; however, the sample color changed from colorless to pale yellow, and the acid value increased significantly; this confirms that after the preceding complexation, adsorption, and demetallization steps were omitted, the residual carbonyl compounds and metal ions in the raw materials directly affected the initial color and acidity of the fuel, producing discernible differences in basic physicochemical indicators. In Comparative Example 2, after replacing the low-molecular-weight co-solvent with a high-HLB surfactant, the system exhibited a milky, slightly turbid appearance, with increased kinematic viscosity and a higher closed-cup flash point, while the acid value was only slightly higher than in the Example. This phenomenon is attributed to the fact that the introduction of the macromolecular surfactant increased internal friction and restricted the volatilization of light components, leading to a simultaneous increase in viscosity and flash point. Furthermore, it facilitated micro-phase separation, resulting in visible turbidity. Under the premise of an intact antioxidant system, the acid value did not deviate drastically. In Comparative Example 3, after removing the oil-based primary amine and methylbenzotriazole (TTA), the viscosity, flash point, and appearance color showed limited changes compared to the Example, but the acid value increased slightly. This indicates that, under the condition that the basic formulation and front-end purification process remain unchanged, removing the interfacial protectant has little impact on the initial physical properties of the fuel, but its effects on acid-base buffering and metal surface passivation are weakened, directly reflected in a decreased ability to inhibit acid value growth. Comparative Example 4 removed the high-shear dispersion, vacuum degassing, and 0.2 μm fine filtration steps and replaced the static mixing process with a single high-pressure homogenization. The result was that the viscosity and flash point remained at the same level as the example, but the appearance showed slight turbidity and a small amount of bubbles, and the acid value increased slightly. This proves that when the formulation is constant, the simplification of the process route - especially the absence of cleaning operation and degassing steps - will first expose defects in the optical uniformity of the product, and then trigger initial oxidation, resulting in a slight shift in acid value.

[0059] Combustion and Volatilization Test: The fuel samples from Example 1 and Comparative Examples 1-4 were pre-equilibrated in a 40°C constant temperature water bath for 30 minutes. They were then removed and placed in a pre-weighed shallow dish (100 mm diameter, 6 mm depth, initial fuel volume 25 mL, initial mass of recording dish + sample m0). The dish was then quickly transferred to a 40°C constant temperature oven and allowed to evaporate for 60 minutes. The sample was then removed and re-weighed, with the mass m... 60 And repeat the repositioning-weighing process at the same temperature to confirm that the reading is stable (the difference between two consecutive weighings ≤ 0.001 g); calculate the isothermal evaporation loss (%) = (m0 – m 60) / m0×100%; Each sample was tested three times. After the volatilization test was completed, the higher heating value (HHV) (MJ / kg) of the same batch of samples was determined using the conventional oxygen bomb calorimeter method. ρ was measured using a densitometer at the same temperature (20°C). 20 (kg / L), based on this, the volumetric calorific value HHV(vol) can be calculated as: HHV × ρ 20 (Unit: MJ / L), test results are as follows Figure 1 and Figure 2 As shown.

[0060] based on Figure 1 and Figure 2 The results show that the modified fuels of the present invention exhibit moderate isothermal evaporation loss and high volumetric calorific value, achieving a balance between light-end volatility and energy density. The light-end is not excessively suppressed, thus the evaporation loss is not lower than the limit; simultaneously, the overall formulation maintains higher volumetric energy. Comparative Example 1, lacking front-end purification, showed an increased isothermal evaporation loss of 21.5% and a slight decrease in volumetric calorific value to 18.5 MJ / L. Table 1 also shows a pale yellow appearance and a significant increase in acid value. These phenomena collectively indicate that residual light components and reactive impurities in unpurified raw materials simultaneously lead to increased volatility and a lower overall quality threshold, resulting in a slight impairment of energy density. Comparative Example 2, after replacing the low-molecular-weight co-solvent with a high-HLB surfactant, saw its evaporation loss decrease to 14.8% and its volumetric calorific value to 18.6 MJ / L, slightly lower than Example 1, accompanied by an increased flash point, increased viscosity, and a milky appearance. This indicates that while the macromolecular surfactant can suppress the volatilization of light components, it fails to improve energy density, and its milky appearance reflects the presence of micro-phase separation in the system. Comparative Example 3, after removing the oil-based primary amine and TTA and supplementing with lighter components, exhibited an evaporation loss of 19.6% and a volumetric calorific value of 18.4 MJ / L. Both showed characteristics of lighter substitution, i.e., a slight increase in volatility and a slight decrease in energy. Its acid value was slightly higher than that of Example 1, but the appearance remained basically clear. Without changing the main formulation, the initial thermophysical properties could still be maintained at a reasonable level. Comparative Example 4 only changed the mixing and purification process path. Its evaporation loss and volumetric calorific value remained at 17.2% and 18.8 MJ / L, respectively, which were basically equivalent to those of Example 1. The previously observed slight turbidity, microbubbles, and slight increase in acid value did not have a significant impact on the thermophysical properties, indicating that the influence of process cleanliness was more reflected in the appearance and chemical stability boundary, and did not significantly change the volatility and energy readings within the test window.

[0061] Corrosion Test: A copper sheet corrosion test was conducted according to GB / T 5096-2017. A standard copper sheet polished to a mirror finish (initial mass m0) was completely immersed in the corresponding fuel samples (Example 1 and Comparative Examples 1-4 fuels). The samples were placed in a constant temperature chamber at 70°C and kept in the dark for 168 hours. After removal, the surface was quickly wiped clean with lint-free paper, and the sample was left at room temperature for 30 minutes before being weighed (m1). The mass change rate (%) was calculated as (m1-m0) / m0 × 100%. Results are as follows: Figure 3 As shown.

[0062] based on Figure 3 The results show that the modified fuel in the embodiments of the present invention has the smallest weight loss and the fuel has a very weak tendency to corrode copper sheets. Comparative Example 1 did not implement front-end purification, and its copper sheet mass change rate was significantly higher than that of the embodiments; this indicates that the unremoved active trace components and metal residues lead to a decrease in the initial chemical stability of the system, and the corrosive environment is more active. Even if the subsequent formulation and process steps are consistent with the embodiments, it is still difficult to restore to a low corrosion level. Comparative Example 2 used a high HLB value surfactant to replace the low molecular weight co-solvent, and its copper sheet mass loss was higher than that of the embodiments, but significantly lower than that of Comparative Example 1 and Comparative Example 3; this indicates that when the oil-based primary amine and TTA and other interfacial protectants are retained, the metal surface still has a certain protective ability, and corrosion is not further amplified; however, the changes in the system state caused by the change in the phase stability path (such as the opaque appearance and the shift in physical properties) did not bring additional corrosion inhibition effect. Comparative Example 3 showed the most significant mass loss in copper sheets after the removal of the primary amine and TTA. This indicates that although the initial appearance was close to clear and the acid value only increased slightly, the protective ability of the metal surface was directly weakened in the absence of an interfacial protectant, making it more susceptible to corrosion during immersion. This reflects the crucial role of the interfacial protectant in long-term compatibility. Comparative Example 4 altered the mixing and cleaning path, and its mass loss fell between that of the Example and Comparative Example 1 / 3. This difference mainly stemmed from the weakening of the cleanliness of the medium and the initial stability boundary, rather than a fundamental change in the formulation. Although the thermophysical properties were not significantly affected, the simplification of the process resulted in a decrease in system homogeneity and cleanliness, which still had an observable negative impact on corrosion behavior.

[0063] Stability and anti-aging test: Fuel samples from Example 1 and Comparative Examples 1-4 were loaded into a pressure oxidation tester. High-purity oxygen was introduced at 20°C for 1 min, followed by oxygenation to an initial oxygen pressure of 700 kPa. The temperature was raised to 140°C and held constant, with pressure-time curves recorded. The time when the pressure first showed a sustained and rapid decrease, reaching 10% of the initial pressure, was defined as the oxidation induction period (min). Subsequently, metal catalytic storage aging was performed: a polished and degreased copper / brass sample assembly (total wetting surface area 50 cm²) was placed in each sample. 2 / L), and placed at 60°C in a light-proof, sealed environment, samples were taken at 24h, 72h, and 168h, and the acid value was measured (GB / T7304-2014). The acid value growth rate (mg·KOH / (g·d)) was calculated as (acid value at sampling - initial acid value) / (sampling time / 24h). The appearance change was also recorded at 168h. The test results are as follows. Figure 4 and Figure 5 As shown in Table 2, the results of the appearance changes are as follows.

[0064] Table 2. Results of Appearance Changes in Examples and Comparative Examples

[0065]

[0066] based on Figure 4 , 5 As shown in Table 2, the modified fuel of this invention exhibits the longest induction period under pressurized oxidation and the slowest increase in acid value under metal-catalyzed storage aging, remaining clear even after 168 hours. Comparative Example 1, due to the omission of the front-end purification step, failed to effectively remove easily oxidizable carbonyl precursors and trace metal ions, leading to a deterioration in the system's chemical stability from the initial stage. This deficiency is evident in multiple test dimensions: increased acid value and color in basic physicochemical indicators, increased evaporation loss in volatility performance, and a shortened oxidation induction period and accelerated acid value increase rate in aging tests, resulting in overall poor anti-aging performance. Comparative Example 2 replaced the low-molecular-weight co-solvent with a high-HLB surfactant, causing the system to shift from a stable, easily recoverable, and poorly bound phase to a state prone to emulsification and component binding. This change manifested in volatilization and combustion tests as reduced evaporation loss, a higher flash point, and increased viscosity, while maintaining an appearance of continuous emulsification. Although the pre-treatment purification and interface passivation steps were retained, which to some extent suppressed further deterioration of chemical aging and corrosion, its oxidation induction period and acid value increase were still lower than those of Example 1. Comparative Example 3, after removing the oil-based primary amine and TTA as interface protection components and supplementing with lighter components, lacked a key metal surface barrier, and the overall formulation was lighter. The effects were reflected not only in a slight increase in volatilization and a small decrease in volumetric energy, but more significantly in corrosion and metal catalytic aging: this group showed the highest acid value increase rate during storage aging, indicating that its aging sensitivity increased significantly once in a metal catalytic environment. Comparative Example 4 simplified the process path while keeping the formulation unchanged, including removing the high-shear, degassing and fine filtration steps, and replacing static mixing with single high-pressure homogenization. This adjustment did not significantly affect the thermal properties and volumetric energy, but it resulted in the appearance of slight turbidity and microbubbles, and the corrosion and aging readings also deteriorated slightly. The oxidation induction period and acid value growth were at a mid-level, indicating that the process cleanliness and construction method have a clear impact on the long-term stability of the system.

[0067] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a green, low-carbon, and highly efficient modified fuel for an alcohol-hydrogen engine, characterized in that, Specifically, the following steps are included: S1: Crude bio-methanol is placed in a stirred tank, filtered through a PP filter cartridge, and then 3A molecular sieve is added and stirred for adsorption; then online vacuum distillation is carried out, and the methanol fraction is collected under vacuum to obtain refined methanol; S2: Add sodium bisulfite-methanol solution dropwise to the purified methanol in step S1, stir to react and complex trace amounts of formaldehyde / acetaldehyde; add activated carbon for adsorption, filter with ceramic membrane; add iminodiacetic acid chelating resin for recycling treatment to obtain pretreated bio-methanol; S3: Add 2-methyltetrahydrofuran, methyl formate, glyceryl monooleate, trifluoropropyl silicone oil and polyether-modified organosilicon to the stirred tank in sequence, and stir. After each component is added, stir at a constant temperature. After mixing is complete, raise the temperature and perform high-shear pre-dispersion to obtain mother liquor A. S4: Add dimethoxymethane, isobutanol and oleyl amine to the container in sequence, heat and stir at a constant temperature, dissolve methylbenzotriazole in dimethoxymethane to prepare a mother liquor and then slowly add it; then add propyl gallate and tocopherol, stir at a constant temperature to obtain mother liquor B; S5: Slowly pump the mother liquor B from step S4 into the mother liquor A from step S3, maintaining a constant temperature; perform high-shear mixing; degas under vacuum, let stand; and filter to obtain a concentrated solution. S6: Add deionized water to the pretreated bio-methanol from step S2 until the target water content is 1-1.5 wt%, stir, slowly add the concentrate from step S5, stir, vacuum degas, statically mix, finally filter, let stand to defoam, and obtain green, low-carbon, and high-efficiency modified fuel.

2. The method for preparing a green, low-carbon, and high-efficiency modified fuel for an alcohol-hydrogen engine according to claim 1, characterized in that, In step S1, the crude bio-methanol is prepared by gasification synthesis using at least one of the following raw materials: biological waste straw, forestry residue, and organic waste.

3. The method for preparing a green, low-carbon, and highly efficient modified fuel for an alcohol-hydrogen engine according to claim 1, characterized in that, In step S1, the amount of 3A molecular sieve added is 1.5-2% based on the mass fraction of crude bio-methanol.

4. The method for preparing a green, low-carbon, and high-efficiency modified fuel for an alcohol-hydrogen engine according to claim 1, characterized in that, In step S2, the recycling parameters of the iminodiacetic acid chelating resin are: 5-10 wt% aqueous methanol as the working medium, 2-5 BV / h recycling until the output metal is <0.5 ppm.

5. The method for preparing a green, low-carbon, and highly efficient modified fuel for an alcohol-hydrogen engine according to claim 1, characterized in that, In step S3, the mass ratio of 2-methyltetrahydrofuran, methyl formate, glyceryl monooleate, trifluoropropyl silicone oil and polyether-modified organosilicon is 0.6–0.85:0.14–0.25:0.32–0.54:0.06–0.12:0.08–0.

14.

6. The method for preparing a green, low-carbon, and highly efficient modified fuel for an alcohol-hydrogen engine according to claim 1, characterized in that, In step S4, the mass ratio of dimethoxymethane, isobutanol, oleyl amine, methylbenzotriazole, propyl gallate, and tocopherol is 0.4–0.55:0.25–0.32:0.06–0.1:0.001–0.002:0.04–0.06:0.049–0.

068.

7. The method for preparing a green, low-carbon, and high-efficiency modified fuel for an alcohol-hydrogen engine according to claim 1, characterized in that, In step S5, the mass ratio of mother liquor B to mother liquor A is 0.8-1.1:1.2-1.

9.

8. The method for preparing a green, low-carbon, and high-efficiency modified fuel for an alcohol-hydrogen engine according to claim 1, characterized in that, In step S6, the amount of the concentrated liquid added is 2-3% based on the mass fraction of refined methanol.

9. The method for preparing a green, low-carbon, and high-efficiency modified fuel for an alcohol-hydrogen engine according to claim 1, characterized in that, In step S6, the static mixing parameters are as follows: the material is pumped into a static mixer with 6 to 12 mixing sections via a gear pump, and Re is controlled to be ≥5000 and the linear velocity is 1.5 to 2.5 m / s; an online turbidity detector is installed at the outlet, and Δturbidity <5 NTU is used as the threshold for completion of mixing.

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