Alcohol-based fuel additive, preparation method and application thereof

Abstract

This invention relates to an alcohol-based fuel additive, its preparation method, and its application, belonging to the technical field of diesel fuel additives. The additive, by weight, comprises: a mixture of C3-C10 fatty alcohols, fatty acid methyl esters, methyl tert-butyl ether, isoamyl nitrate, dimethyl carbonate, and diesel fuel. The mass ratio of methyl tert-butyl ether to dimethyl carbonate is [value missing]. This invention employs a stepped feeding process, solving the problem of combustion improver failure caused by high shear heat generation by cooling the fuel before adding isoamyl nitrate, and ensuring long-term fuel stability at -10°C using a specific polarity gradient ratio. The fuel prepared by this invention has a high cetane number, strong power, and good anti-stratification effect, making it suitable for compression ignition engines.

Description

Technical Field

[0001] This invention belongs to the field of diesel additive technology, specifically relating to an alcohol-based fuel additive, its preparation method, and its application. Background Technology

[0002] Alcohol-based fuels, as a clean and renewable alternative energy source, have broad application prospects in the field of compression-ignition engines. However, methanol and other low-carbon alcohols are highly polar solvents (dielectric constant of approximately 33), while petrochemical diesel is composed of non-polar long-chain alkanes, cycloalkanes, and aromatics. The significant difference in solubility parameters between the two makes the alcohol-oil system thermodynamically unstable. In practical applications, drastic fluctuations in ambient temperature (especially in low-temperature winter environments) can disrupt the original microemulsion dynamic equilibrium of the system, leading to severe phase separation and emulsion stratification problems.

[0003] To address the aforementioned challenges, existing technologies typically employ methods such as introducing cosolvents, surfactants, and modifiers to improve system stability. For example, Chinese invention patent CN104745243B discloses a methanol-diesel additive and its preparation method, which involves compounding nine components, including dimethyl carbonate (DMC), ethers, alcohols, preservatives, and antioxidants. While this existing patent improves the miscibility of methanol and diesel to some extent, it still reveals the following specific technical bottlenecks in practical industrial applications and under extreme operating conditions: First, existing technologies lack precise polar gradient control in limiting the synergistic ratio of co-solvent components. While CN104745243B utilizes both DMC and ethers, its formulation primarily uses components in broad mass fractions, failing to adequately consider the competitive adsorption balance at the interface between strongly polar components (such as methanol) and non-polar components (such as long-chain alkanes in diesel fuel). When ambient temperatures drop to -10°C or even lower, the hydrogen bond network structure within the system is highly susceptible to collapse due to reduced thermal motion, leading to micelle aggregation and precipitation. This microscopic phase separation not only results in uneven fuel composition but also causes lubrication interruption in the engine's fuel injection pump during low-temperature startup due to the introduction of an alcohol-rich phase, accelerating component wear.

[0004] Secondly, existing technologies generally employ the conventional "sequential addition and mixing" process logic in their preparation. In actual production, achieving microscopic homogeneity in complex multi-component systems necessitates high-energy input methods such as high-shear emulsification or ultrasonic dispersion. However, cetane number improvers like isoamyl nitrate are highly heat-sensitive components. When subjected to localized temperature rises (typically instantaneous rises of 45°C-60°C) caused by high shear forces, the nitrate ester groups in their molecular chains are prone to premature oxidative decomposition or free radical polymerization. The preparation process described in existing patent CN104745243B lacks specific design for the feeding points and heat dissipation paths of the heat-sensitive components, resulting in damage to the combustion-promoting active components in the finished additive. This leads to large cetane number fluctuations, prolonged ignition delay time, and increased fuel consumption in subsequent bench tests, making it difficult to meet the stringent fuel quality requirements of high-pressure common rail systems.

[0005] Furthermore, existing solutions often require the addition of multiple preservatives and antioxidants to compensate for the inherent instability of the system, increasing formulation complexity and production costs. Therefore, how to simplify the components while ensuring the all-weather stability and integrity of the active components of alcohol-based fuels through precise matching of polarity gradients and dynamic control of process temperature is a problem that needs to be solved in this field. Summary of the Invention

[0006] The purpose of this invention is to provide an alcohol-based fuel additive, its preparation method, and its application, which solves the problems in the prior art where alcohol-based fuels and petrochemical diesel are prone to micro-phase separation at low temperatures, and where the local temperature rise caused by high shear energy input in traditional preparation processes leads to premature oxidation and failure of heat-sensitive combustion-supporting components.

[0007] The objective of this invention can be achieved through the following technical solutions: An alcohol-based fuel additive, comprising, by weight, the following components: 45-55 parts of a mixture of C3-C10 fatty alcohols; Fatty acid methyl ester: 3-8 parts; methyl tert-butyl ether: 8-12 parts; isoamyl nitrate: 0.5-3 parts; dimethyl carbonate: 4-6 parts; diesel oil: 20-30 parts; wherein the mass ratio of methyl tert-butyl ether to dimethyl carbonate is 1.5:1 to 2.5:1; To address the phase separation (stratification) problem caused by the thermodynamic instability of highly polar methanol and non-polar diesel under extreme temperature differences, the principle of "polar gradient coupling" is utilized. The solubility parameters of methanol are also discussed. diesel alkanes By limiting the specific mass ratio of methyl tert-butyl ether (MTBE) to dimethyl carbonate (DMC), a buffer phase of moderate polarity was constructed within the system. In addition, DMC molecules contain carbonyl groups. It has a strong dipole moment and is responsible for forming hydrogen bonds with methanol. MTBE, as an ether, has ether bonds. With relatively weak polarity, it mainly interacts with diesel hydrocarbons through van der Waals forces. Within this ratio range, the branched tert-butyl structure of MTBE provides excellent steric hindrance, preventing excessive aggregation of coupling clusters formed by DMC and methanol, thus ensuring stable operation under normal pressure. This forms a long-term stable microemulsion system.

[0008] Preferably, by weight, it comprises the following components: C3-C10 mixed fatty alcohols: 50.0 parts; fatty acid methyl esters: 5.0 parts; methyl tert-butyl ether: 10.0 parts; isoamyl nitrate: 1.0 part; dimethyl carbonate: 5.0 parts; diesel oil: 25.0 parts; Locate an experimentally validated optimal equilibrium point within a broad range, ensuring that... to There is no precipitation in the storage and transportation temperature range. Through the fixed ratio between components, the overall hydrophilic-lipophilic balance value (HLB value) of the additive is completely matched with the requirements of alcohol-based fuel.

[0009] Furthermore, the C3-C10 mixed fatty alcohol is selected from at least one of straight-chain fatty alcohols or branched fatty alcohols having the number of carbon atoms from C3 to C10; the C3-C10 mixed fatty alcohol comprises n-butanol and isoamyl alcohol in a mass ratio of 0.8:1 to 2.0:1. To address the issue of insufficient interfacial film strength caused by the overly regular arrangement of a single type of alcohol on the interfacial film, n-butanol ( ) has a straight-chain structure, isoamyl alcohol ( The structure is branched; at the interface, the branched isoamyl alcohol can embed into the gaps between the straight-chain n-butanol, increasing the molecular density and surface pressure of the microemulsion droplet surface film. The steric synergy resulting from these different molecular geometries effectively prevents the coalescence of methanol droplets, thereby significantly improving the kinetic stability of the fuel at low temperatures.

[0010] Furthermore, the carbon chain length of the fatty acid methyl ester is C16 to C18, and the iodine value of the fatty acid methyl ester is not greater than 120 g I2 / 100g. To address the issues of oil pump wear due to lack of lubricity in methanol fuel and insufficient "grabbing power" of the formulation at the oil-ethanol interface, fatty acid methyl esters ( )of Long carbon chains have strong oleophilicity, allowing them to penetrate deep into the diesel phase and act as an "anchor," increasing iodine value. The restriction is to control the number of double bonds, double bonds ( In the high temperature and high pressure environment of the engine, free radical polymerization is prone to occur, leading to coking. The low iodine value ensures the thermal stability of the additive, avoids the formation of carbon deposits at the fuel injector, and ensures the accuracy of the fuel injection pattern.

[0011] Furthermore, the diesel fuel has a cetane number of not less than 51 and a pour point between −15°C and 0°C. Using high cetane diesel as an ignition source, the pour point is lowered to ensure... The system does not produce solid paraffin crystal nuclei, thus solving the problems of ignition lag (difficulty in ignition) caused by the low cetane number of methanol and the destruction of the emulsion system by oil wax precipitation at low temperatures.

[0012] A method for preparing an alcohol-based fuel additive includes the following steps: (1) Premixing: The C3-C10 mixed fatty alcohol and the fatty acid methyl ester are mixed and stirred to obtain a premixed solution; (2) Miscibility treatment: The methyl tert-butyl ether and the dimethyl carbonate are mixed and then added to the premixed solution to obtain a composite solubilizing system; (3) Homogeneous dispersion: The diesel oil is added to the composite cosolvent system for shear emulsification, and then the isoamyl nitrate is added to obtain the alcohol-based fuel additive; Step (1) first couples the C3-C10 mixed fatty alcohols with the methyl ester to establish a lipophilic base. Step (2) adds ethers and esters to expand the base using the solvation effect. Step (3) involves high-shear emulsification. This is to provide sufficient mechanical energy to strip the large molecular clusters of diesel fuel, allowing them to be encapsulated layer by layer by the cosolvent molecules. This gradual process ensures that each active component appears at its proper interface position, thus solving the problem of incomplete emulsification caused by competitive adsorption of components in the traditional "one-pot method".

[0013] Furthermore, all steps (1) to (3) are carried out under nitrogen protection, and the system temperature before adding the isoamyl nitrate in step (3) is not higher than 30°C. Nitrogen protection This prevents oxygen from the air from participating in side reactions to produce hydrogen peroxide, and the system temperature... Isoamyl nitrate ( In ) The bond energy is relatively low. Under the mechanical and thermal influence of high-shear equipment, if the temperature exceeds... Nitrates are highly susceptible to pyrolysis, releasing nitrogen oxide free radicals, which not only leads to the loss of combustion-supporting effect, but also causes the fuel to darken in color and increase in acid value. This solves the problem of heat-sensitive components such as isoamyl nitrate being oxidized or decomposed and rendered ineffective during the preparation process.

[0014] A hybrid new energy alcohol-based fuel, by weight, comprises: methanol: 72.5-84.5 parts; and the alcohol-based fuel additive: 15.5-28 parts; ensuring that the additive is mixed with a high proportion of methanol. Even after dilution, the critical micelle concentration of the microemulsion droplets can still be maintained. .

[0015] Furthermore, the purity of the methanol is not less than 99.5 wt%, and the water content in the methanol is not higher than 0.1 wt%; water is a highly polar substance. Because water molecules are small, they readily occupy hydrogen bond positions in DMC and C3-C10 mixed fatty alcohols, forcing methanol to precipitate from the microemulsion system and limiting water content. This is the physical prerequisite for maintaining this complex multi-component system in a "quasi-homogeneous" state.

[0016] The application of an alcohol-based fuel additive, or a blend of new energy alcohol-based fuels, in compression ignition engine fuels; the principle of compression ignition combustion adaptability, through the improvement of methanol spray characteristics by the additive, enabling it to operate under high temperature and high pressure in the compression ignition chamber. Achieve multi-point synchronous spontaneous combustion in the environment.

[0017] The beneficial effects of this invention are: 1. Regarding methanol (solution parameter) in the background technology With diesel alkanes The significant difference in polarity presents a technical bottleneck. This invention addresses this by limiting methyl tert-butyl ether (MTBE) and dimethyl carbonate (DMC) to... By utilizing the specific mass ratio of the two molecules and their complementary polarities, a "molecular bridge" with a continuous polar transition is constructed within the system. The main principle is that the carbonyl group in the DMC molecule... As a strongly polar center, it can form strong hydrogen bonds with the hydroxyl group of methanol. ; while the ether bond of MTBE ( The polarity is relatively weak, and the tert-butyl group at its molecular end has strong lipophilicity. At this specific ratio, the two components alternate at the oil-alcohol interface, forming a dynamically balanced microemulsion layer. This scheme enables the blended fuel to... to Standing at extreme low temperatures Even after more than 10 days, it does not separate into layers, solving the problem that existing technologies are prone to emulsification and separation in cold seasons, and the resulting interruption of oil pump lubrication.

[0018] 2. This invention limits the mass ratio of n-butanol to isoamyl alcohol in a C3-C10 mixed fatty alcohol to 0.8:1 to 2.0:1. Utilizing the synergistic effect of different molecular geometries, the mechanical strength of the interfacial film is optimized, primarily due to the synergistic effect of n-butanol. It has a straight-chain structure with a relatively tight arrangement; isoamyl alcohol It has branched chains. On the surface of microemulsion droplets, branched isoamyl alcohol can effectively embed itself in the gaps between straight-chain n-butanol. This "intercalation" arrangement increases the surface pressure of the interfacial film. And steric hindrance. Compared to a single type of C3-C10 mixed fatty alcohol, this mixed alcohol system can generate stronger repulsive forces, preventing methanol droplets from coalescing in Brownian motion, thereby ensuring the physical stability of the fuel during long-term storage and transportation.

[0019] 3. Addressing the technical obstacle of amyl nitrate's susceptibility to thermal decomposition under high shear conditions in the background art, this invention employs a three-step stepped feeding method and... Low-temperature feedback control, isoamyl nitrate nitrate bonds It has low bond energy and is extremely sensitive to heat. In the traditional one-pot process, high-shear emulsification... The generated mechanical energy will be rapidly converted into internal energy, causing the system's instantaneous temperature rise to exceed [a certain value]. This invention employs a process of first coupling and miscibility (steps 1 and 2), followed by forced cooling before the addition of isoamyl nitrate, to physically encapsulate it within the pre-formed composite solubilizing system. This process effectively avoids the oxidative decomposition of the active component and free radical autocatalytic reactions, ensuring that the measured cetane number of the finished fuel remains stable at [value missing]. The above significantly improves the ignition delay and enhances the engine's power response.

[0020] 4. This invention limits the iodine value of fatty acid methyl esters to no greater than [value missing]. And the carbon chain is It mainly consists of long-chain fatty acid methyl esters. It can firmly adsorb onto metal surfaces to form a boundary lubrication film, compensating for the inherent poor lubricity of methanol. Simultaneously, the iodine value is strictly limited (i.e., the unsaturated double bonds in the molecule are restricted). The quantity is to prevent fuel from being trapped in the engine's high-pressure common rail (pressure can reach...). The above) and the free radical polymerization and coking that occur under high temperature conditions ensure that the fuel injector does not carbonize or clog, maintains the precise injection angle of fuel atomization, and thus reduces the specific fuel consumption in bench tests. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the microemulsification mechanism of the alcohol-based fuel additive of the present invention; Figure 2 This is a schematic diagram of the stepwise preparation process of the additive of the present invention. Detailed Implementation

[0023] The technical solutions 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. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0024] like Figure 1 As shown in the figure, the source of methanol (a highly polar solvent) is clearly marked. From diesel (non-polar, The transition layer consists of dimethyl carbonate (DMC) tightly adhering to the methanol core, and methyl tert-butyl ether (MTBE) distributed on the outside of DMC. The two are combined in a specific ratio to eliminate interfacial tension between the two phases. The figure shows fatty acid methyl esters with long carbon chains and mixed C3-C10 fatty alcohols. The long-chain portions act as "anchors" penetrating deep into the diesel phase, while the steric hindrance created by branched structures (such as isoamyl alcohol) effectively prevents the aggregation of methanol particles.

[0025] like Figure 2 As shown in the diagram, this flowchart illustrates the complete industrialization path of additives from raw material preparation to final product output. Stage 1 (Coupling): The diagram shows C3-C10 mixed fatty alcohols and fatty acid methyl esters entering the reactor first. The significance of this step lies in "molecularly cleaving" the viscous methyl esters through alcohols, pre-establishing a lipophilic base. Stage 2 (Rearrangement): Subsequently, MTBE and DMC are added, marked "hydrogen bond rearrangement." This step is crucial for adjusting the system's polarity; the diagram shows the system changing from turbid to transparent. Stage 3 (Homogenization and Protection): After introducing diesel fuel, high-energy processing is performed using a high-shear emulsifier (shear rate indicated). ), Key temperature control branch: A dedicated cooling water circulation line is shown in the diagram, marked with " "Only after this temperature control point can the heat-sensitive isoamyl nitrate be added."

[0026] I. Broad Interpretation and Functional Definition of Core Components: In this invention, "C3-C10 mixed fatty alcohols" refers to straight-chain or branched fatty alcohols with a greater number of carbon atoms than ethanol, preferably fatty alcohols with a carbon number of C3-C10. In the mixing system of this invention, C3-C10 mixed fatty alcohols not only act as co-solvents, but more importantly, their longer hydrophobic carbon chains form steric hindrance with the hydrophilic hydroxyl groups of methanol, thereby building a "microemulsification bridge" between polar methanol and non-polar diesel fuel, fundamentally suppressing stratification and poor emulsification caused by sudden temperature changes.

[0027] To comprehensively cover possible implementation methods and prevent circumvention, the C3-C10 mixed fatty alcohols are not limited to the preferred n-butanol (CAS No.: 71-36-3) and isoamyl alcohol (CAS No.: 123-51-3) mentioned in the examples, but also explicitly include, but are not limited to, one or more combinations of the following specific compounds: n-Propanol (CAS No.: 71-23-8) Isopropyl alcohol (CAS No.: 67-63-0) Isobutanol (CAS No.: 78-83-1) n-Pentanol (CAS No.: 71-41-0) n-Hexanol (CAS No.: 111-27-3) Isooctyl alcohol / 2-ethylhexanol (CAS No.: 104-76-7) In this invention, fatty acid methyl esters, as long-chain ester compounds, primarily function to compensate for the inherent lack of lubricity in methanol molecules. They can adhere to the surfaces of engine injectors and cylinder walls to form a strong oil film, effectively addressing the technical biases of poor lubrication efficiency and increased mechanical wear associated with methanol fuel.

[0028] To ensure the wide availability of raw material sources and industrial applicability, the fatty acid methyl esters include products obtained through transesterification or esterification reactions of different oil and fat raw materials, with specific sources including but not limited to: Waste oil fatty acid methyl esters are obtained by purifying and esterifying waste animal and vegetable oils (commonly known as gutter oil or swill oil); Soybean oil fatty acid methyl esters obtained by esterification of soybean oil; Palm oil fatty acid methyl esters obtained by esterification of palm oil; Vegetable oil-based fatty acid methyl esters derived from rapeseed oil or peanut oil.

[0029] Physical / chemical significance of core characteristic parameters and their contribution to the invention In the technical solution of this invention, specific physicochemical parameters are introduced to limit the components. These parameters are not arbitrarily selected, but have a direct causal relationship with achieving the core purpose of this invention (preventing stratification and maintaining power).

[0030] Iodine value (a key indicator for defining fatty acid methyl esters), parameter explanation: Iodine value is used to characterize the degree of unsaturation (number of double bonds) of the carbon chain in fatty acid methyl esters. In this invention, the iodine value of the fatty acid methyl ester is required to be no greater than 120 g I2 / 100g.

[0031] The technical contribution of this invention is as follows: An excessively high iodine value indicates an excessive number of double bonds. Under the high temperature and pressure environment of the engine combustion chamber, fuel is highly susceptible to oxidative cross-linking and polymerization reactions, leading to coking and blockage of the fuel injectors. This coking severely impairs fuel atomization, resulting in low fuel efficiency and reduced power. By strictly defining the upper limit of the iodine value, this invention ensures that fatty acid methyl esters provide lubrication while possessing excellent thermal oxidative stability, thereby guaranteeing a continuous and stable output of engine power.

[0032] Cetane number (a key indicator for limiting diesel and finished fuels), parameter explanation: The cetane number is an indicator that measures the ignition delay period of fuel in compression ignition engines. The higher the cetane number, the better the auto-ignition properties of the fuel and the shorter the ignition delay period.

[0033] Technical contributions of this invention: The biggest technical obstacle to alcohol-based fuels (methanol) lies in their extremely low cetane number (typically less than 5), resulting in a low ignition point, difficulty in cold starting, and a high tendency for knocking. This invention, by limiting the cetane number of the base diesel fuel (not less than 51) and introducing isoamyl nitrate (a cetane number improver) at specific feeding times, forcibly enhances the auto-ignition performance of the overall fuel mixture. This directly solves the problem in the prior art that methanol fuel cannot be directly applied to compression-ignition diesel engines, completely reversing the disadvantage of reduced power.

[0034] Pour point (a key indicator limiting anti-phase separation ability), parameter definition: Pour point refers to the highest temperature at which an oil product loses its fluidity under specified conditions. Technical contribution of this invention: In an alcohol-oil mixture, once the temperature drops to near the pour point, high-carbon alkanes in diesel fuel or saturated lipids in fatty acid methyl esters will be the first to precipitate wax crystals. These tiny crystals will rapidly puncture the "microemulsion network" constructed by MTBE and DMC in this invention, triggering a domino effect of severe stratification and loss of oil-dissolving effect. Therefore, the selection and limitation of the pour point of diesel fuel (e.g., 0°C to -15°C) in the embodiments of this invention is the physical basis for ensuring that this new energy fuel can maintain single-phase homogeneity and stability and avoid poor emulsification and stratification in extremely cold regions.

[0035] II. Description of Experimental Materials and Key Equipment To demonstrate that those skilled in the art can implement this invention based on the description, the specific experimental materials and key equipment used in the embodiments and comparative examples are described in detail. Unless otherwise specified, the raw materials and reagents used in the embodiments of this invention are all commercially available products, and the process equipment used are all conventional equipment in the art or commercially available equipment adapted for adaptation.

[0036] Regarding the source and specifications of core raw materials, in order to ensure the specific "synergistic microemulsification" and "antioxidant and flame-stabilizing" effects of this invention, the purity, grade, and specific source of the raw materials in this embodiment of the invention have been strictly screened. The specific list is as follows: n-Butanol and isoamyl alcohol (C3-C10 mixed fatty alcohol components): Both were of analytical grade (AR, purity ≥99.5%). High purity avoids interference from impurity ions on the subsequent formation of hydrogen bond networks.

[0037] Fatty acid methyl ester: Industrial-grade low-iodine-value soybean oil fatty acid methyl ester is used. The measured iodine value is 105 g I2 / 100g, and the density (20℃) is about 0.88 g / cm³. The low iodine value is specified to support the technical effect of this invention in preventing coking of fuel injectors.

[0038] Methyl tert-butyl ether (MTBE) and dimethyl carbonate (DMC): Both are anhydrous industrial grade with a purity of ≥99.9% and a moisture content controlled below 50 ppm. Strict control of moisture content is to prevent premature phase separation during the coupling stage.

[0039] Isoamyl nitrate (combustion improver): Analytical grade (AR, purity ≥99.0%) was used. Diesel fuel (base oil): -10# automotive diesel fuel conforming to China VI standard was used, with a measured cetane number of 52.5 and a measured pour point of -10℃.

[0040] Methanol (for final blending): Superior grade (GR, purity ≥99.8%) with a water content ≤0.05 wt% is used to eliminate the negative impact of external moisture on the low-temperature phase separation test data.

[0041] Key core equipment parameters (high-shear coupling equipment): In the "three-step stepped feeding" process of this invention, the third stage of homogenization is crucial in determining the final physical stability of the mixed fuel. Conventional anchor or paddle mixers cannot provide sufficient shear force to break up non-polar diesel agglomerates. Therefore, the following core equipment is specifically used and defined in this embodiment of the invention: High-shear emulsifier: Employs a laboratory / industrial grade intermittent high-shear dispersion emulsifier; Stator and rotor structure: The core working head adopts a claw-type interlocking bidirectional suction structure or a precision mesh stator. This structure can generate intense hydraulic shearing, centrifugal extrusion, and liquid layer friction within the narrow stator-rotor gap.

[0042] Operating parameters are limited: The rated speed of the equipment can reach up to 10,000 rpm. In process step (3) of this invention, the operating speed is precisely controlled by a frequency converter to achieve a rotor edge linear velocity of 15-25 m / s, thereby generating a limited effective shear rate of 2000-3000 s⁻¹ in the reaction system. This specific high-shear environment is the physical guarantee for forcing macromolecular diesel oil and polar alcohol ester co-solvent to form a stable thermodynamic "pseudo-homogeneous" system.

[0043] Temperature-controlled reactor: A jacketed stainless steel reactor used in conjunction with an emulsifier is equipped with a precise refrigerant circulation system to ensure that when the heat-sensitive "isoamyl nitrate" is added in the final step, the mechanical heat generated by high shear can be quickly removed, and the system temperature can be strictly controlled below 30°C.

[0044] III. Testing Methods and Evaluation Standards: To objectively and accurately verify the comprehensive physicochemical properties and technical effects of the alcohol-based fuel additive and the blended new energy alcohol-based fuel described in this invention, All embodiments and comparative examples of this invention were measured using the following unified test methods and evaluation standards. Unless otherwise explicitly stated, routine operations were carried out at an ambient temperature of 20℃-25℃ and at standard atmospheric pressure.

[0045] 1. Routine physical and chemical properties and combustion index tests This invention strictly adheres to national mandatory or recommended standards for the standardized measurement of industry-standard performance indicators to ensure the objectivity and comparability of the data. Kinematic viscosity: The kinematic viscosity of petroleum products was determined according to GB / T 265-1988 standard "Determination of kinematic viscosity and calculation of dynamic viscosity of petroleum products". The test temperature was set at 20℃ and a standard capillary viscometer was used.

[0046] This indicator is used to evaluate the fuel atomization performance at the fuel injector and its lubrication protection capability for the high-pressure oil pump. Too low kinematic viscosity will lead to mechanical wear (corresponding to the problem of high fuel consumption and poor lubrication efficiency).

[0047] Closed-cup flash point: Determined according to GB / T 261-2008 "Determination of flash point - Binsky-Martin closed-cup method". This indicator is used to evaluate the safety of blended fuels during storage and transportation.

[0048] Cetane number: Determined according to GB / T 386-2010 "Diesel Cetane Number Determination Method" on a standard single-cylinder testing machine (CFR fuel evaluator). This indicator directly reflects the auto-ignition performance and ignition delay period of the fuel in a compression ignition engine (corresponding to solving the core problems of low ignition point and reduced power).

[0049] Bench fuel consumption reduction rate test: An engine bench comparison evaluation method was adopted. The blended fuel prepared according to this invention was compared with commercially available ordinary methanol blended fuel (simple physical mixing only, without the additives of this invention) on a diesel engine bench of the same model. A constant load and constant speed (e.g., 2000 r / min) were set, and the engine was run continuously for 2 hours. The mass of fuel consumed was accurately measured.

[0050] Fuel consumption reduction rate = (commercial fuel consumption - fuel consumption of this invention) / commercial fuel consumption × 100%.

[0051] When conducting bench fuel consumption reduction rate tests, given the physical objective characteristic that high proportion methanol fuel has a low volumetric calorific value, the engine ECU of the test bench has been pre-calibrated for adaptability. By increasing the cyclic injection quantity or pulse width, a constant output power equivalent to the original engine is maintained. Under the premise of equal power output, the test focuses on examining the relative reduction rate of specific fuel consumption brought about by the improvement of atomization and combustion organization by the additives of this invention.

[0052] 2. Core Specialized Test: Accelerated Evaluation Method for Phase Separation Stability Given the lack of a dedicated testing standard for the compatibility of multi-component alcohol-based fuels (especially those containing a high proportion of methanol and petrochemical diesel) under extreme temperature differences in the existing technology, this invention specifically formulates a "low temperature and alternating hot and cold phase separation stability evaluation method". The specific operation and evaluation classification are as follows: Test instruments: 100 mL stoppered high borosilicate transparent glass colorimetric tube (graduation accuracy of 1 mL), programmable high-precision high and low temperature alternating test chamber (temperature control accuracy ±0.5℃).

[0053] Sample preparation: 100 mL of the final mixed fuels prepared in the examples and comparative examples were filled into colorimetric tubes and sealed with polytetrafluoroethylene stoppers to prevent the volatilization of light components (such as MTBE or methanol) from changing the composition of the system.

[0054] Test steps: (1) Extreme low temperature static test: The colorimetric tubes were placed vertically in a constant temperature chamber set at -10℃ and left to stand for 30 days. Observations and records were made every 12 hours during the first 7 days, and then every 24 hours thereafter.

[0055] (2) Temperature Cycling Test (Optional Verification): Place the same packaged sample in an alternating test chamber and perform a cycle of "25℃ (hold for 4 hours) → cool down to -10℃ (hold for 12 hours) → heat up to 25℃" for 10 consecutive cycles. Evaluation Criteria and Data Recording: Under cold light backlighting, record the sample status using a combination of visual observation and high-definition video recording.

[0056] Stabilization period (days): Record the number of days from the start of the test until the first visible milky white turbidity, flocculent suspension, or clear liquid-liquid separation interface appears at the bottom / top of the sample system. A longer stabilization period demonstrates stronger microemulsification and coupling encapsulation capabilities of the additive of this invention. Precipitated phase volume percentage: If separation occurs within 30 days, accurately read and record the volume (in milliliters) of the precipitated phase (usually a lower water-rich methanol phase or an upper hydrocarbon-rich phase) in the colorimetric tube, and calculate its percentage of the total volume.

[0057] Example 1: The Golden Example of Optimal Formulation and Process This embodiment provides an alcohol-based fuel additive and its preparation method, employing the optimal ratio and stepwise process recommended by this invention. The specific operation steps are as follows: (1) Raw material preparation and pretreatment Under a nitrogen atmosphere with a purity of 99.9%, accurately weigh 25 parts of n-butanol, 25 parts of isoamyl alcohol (i.e., a total of 50 parts of C3-C10 mixed fatty alcohols, with a mass ratio of 1:1), 5 parts of soybean oil fatty acid methyl ester with an iodine value of 105 g I2 / 100g, 10 parts of methyl tert-butyl ether (MTBE), 5 parts of dimethyl carbonate (DMC), 1 part of isoamyl nitrate, and 25 parts of -10# diesel fuel conforming to the China VI emission standard. The mass ratio of methyl tert-butyl ether to dimethyl carbonate is strictly controlled at 2:1.

[0058] (2) First stage: Molecular coupling Weighed n-butanol, isoamyl alcohol, and soybean oil fatty acid methyl esters were sequentially added to a reaction vessel equipped with a temperature-controlled jacket. The hot and cold circulation system was activated to precisely lock the system temperature at 28°C and maintain the absolute pressure at 0.1 MPa. The stirring device was started, and the speed was set to 400 rpm, with continuous mixing for 12 minutes. During this process, the initially slightly viscous fatty acid methyl esters rapidly dispersed under the cutting action of the mixed C3-C10 fatty alcohols, and the liquid surface gradually changed from turbid to a uniform pale yellow semi-transparent state, initially completing the molecular coupling of polar and weakly polar components.

[0059] (3) Second stage: hydrogen bond rearrangement and mutual solubility To ensure the co-solvent enters the reaction system at a constant polarity ratio while maintaining a constant temperature of 28°C, the aforementioned weighed methyl tert-butyl ether and dimethyl carbonate were premixed. This mixture was then slowly injected into the premixed solution over a period of 5-10 minutes. Simultaneously, the stirring speed was adjusted to 1000 rpm. After the addition was complete, deep mixing continued for 18 minutes. At this point, due to the extremely strong osmotic pressure formed by the premixing of DMC and MTBE, the hydrogen bond network within the system rearranged, and the liquid surface rapidly collapsed from a semi-transparent state, reforming into an extremely clear and transparent composite co-solvent system.

[0060] (4) Third stage: Homogeneous encapsulation and protection of heat-sensitive components Add -10# automotive diesel fuel to the aforementioned composite co-solvent system in one go. Upon impact from the non-polar long-chain alkanes, the system momentarily exhibits a brief, slight milky-white turbidity. Immediately start the high-shear emulsifier to compensate the shear rate to... After 25 minutes of continuous high-intensity shearing, the milky white color completely disappeared due to the input of mechanical shear energy, and the system regained its clarity.

[0061] Subsequently, 5°C cooling water is introduced through the jacket to ensure that the system temperature drops rapidly to 22°C (it is strictly forbidden to exceed 30°C). Finally, the heat-sensitive combustion-supporting component isoamyl nitrate is added, and the equipment is switched to ordinary paddle stirring mode. It is gently mixed at a low speed of 150 rpm for 8 minutes to finally obtain a clear, transparent, and visually uniform single-phase liquid, which is the alcohol-based fuel additive of this embodiment.

[0062] Example 2: Component content lower limit boundary test The preparation process of this embodiment is the same as that of Example 1, except that the weight proportions of the raw materials are taken as the lower limit of the predetermined range of the present invention: 45 parts of C3-C10 mixed fatty alcohols (n-butanol:isoamyl alcohol = 1:1), 3 parts of fatty acid methyl ester, 8 parts of methyl tert-butyl ether, 4 parts of dimethyl carbonate, 0.5 parts of isoamyl nitrate, and 20 parts of -10# automotive diesel.

[0063] Example 3: Upper Limit Test of Component Content The preparation process of this embodiment is the same as that of Example 1, except that the weight proportions of the raw materials are taken as the upper limit of the predetermined range of the present invention: 55 parts of C3-C10 mixed fatty alcohols (n-butanol:isoamyl alcohol = 1:1), 8 parts of fatty acid methyl ester, 12 parts of methyl tert-butyl ether, 6 parts of dimethyl carbonate, 3 parts of isoamyl nitrate, and 30 parts of -10# automotive diesel.

[0064] Example 4: Lower limit test of synergistic ratio (1.5:1) The preparation process of this embodiment is the same as that of Example 1, except that the mass ratio of methyl tert-butyl ether to dimethyl carbonate is slightly adjusted to verify the proportion boundaries defined by the present invention: 50 parts of C3-C10 mixed fatty alcohols (n-butanol:isoamyl alcohol = 1:1), 5 parts of fatty acid methyl ester, 9 parts of methyl tert-butyl ether, 6 parts of dimethyl carbonate (i.e., MTBE:DMC mass ratio of 1.5:1), 1 part of isoamyl nitrate, and 25 parts of -10# automotive diesel.

[0065] Example 5: Upper limit test of synergistic ratio (2.5:1) The preparation process of this embodiment is the same as that of Example 1, except that the mass ratio of methyl tert-butyl ether to dimethyl carbonate is slightly adjusted to verify the proportion boundaries defined by the present invention: 50 parts of C3-C10 mixed fatty alcohols (n-butanol:isoamyl alcohol = 1:1), 5 parts of fatty acid methyl ester, 10 parts of methyl tert-butyl ether, 4 parts of dimethyl carbonate (i.e., MTBE:DMC mass ratio of 2.5:1), 1 part of isoamyl nitrate, and 25 parts of -10# automotive diesel fuel.

[0066] Example 6: C3-C10 Mixed Fatty Alcohol Substitution Test (Single n-Butanol) The raw material ratio and preparation process of this embodiment are the same as those in Example 1. The core of this embodiment is that 50 parts of C3-C10 mixed fatty alcohols are completely replaced with n-butanol, a single component, and isoamyl alcohol is no longer mixed in, in order to compare the differences in steric hindrance construction of single alcohols.

[0067] Example 7: C3-C10 Mixed Fatty Alcohol Substitution Test (Isoamyl Alcohol Only) The raw material ratio and preparation process of this embodiment are the same as those in Example 1. The core of this embodiment is that 50 parts of C3-C10 mixed fatty alcohols are completely replaced with a single component, isoamyl alcohol, and no n-butanol is mixed in.

[0068] Example 8: Compatibility Test of Base Oil and Lubricating Components This embodiment aims to demonstrate the versatility of this additive in different petrochemical matrices. Its weight ratio and process flow are the same as in Example 1, with the only difference being: Replace the -10# diesel fuel with an equal amount of 0# diesel fuel; at the same time, replace soybean oil fatty acid methyl ester with an equal amount of palm oil fatty acid methyl ester.

[0069] Comparative Example 1: Lack of core polarity regulating components (no DMC) This comparative example provides a comparative preparation scheme with the following component ratios: 50 parts of C3-C10 mixed fatty alcohols (n-butanol:isoamyl alcohol = 1:1), 5 parts of fatty acid methyl ester, 10 parts of methyl tert-butyl ether, 0 parts of dimethyl carbonate (without addition), 1 part of isoamyl nitrate, and 25 parts of -10# automotive diesel fuel. The preparation process is the same as in Example 1.

[0070] Design objective: To verify whether the system can still bind a high proportion of methanol molecules at low temperatures in the absence of dimethyl carbonate (DMC), a highly polar coupling agent.

[0071] Comparative Example 2: Disruption of specific synergistic ratios among components (excessive ratio) This comparative example provides a comparative preparation scheme with the following component ratio: 50 parts of a C3-C10 mixed fatty alcohol (n-butanol:isoamyl alcohol = 1:1), 5 parts of fatty acid methyl ester, 15 parts of methyl tert-butyl ether, 2 parts of dimethyl carbonate, 1 part of isoamyl nitrate, and 25 parts of -10# automotive diesel fuel. In this case, the mass ratio of methyl tert-butyl ether to dimethyl carbonate is approximately 7.5:1, far exceeding the predetermined ratio range of this invention. The preparation process is as described in Example 1.

[0072] Design objective: To demonstrate that the two cosolvents can only produce a synergistic effect within a specific ratio range; once the ratio is out of balance, the hydrogen bond network will not be able to effectively encapsulate nonpolar hydrocarbons.

[0073] Comparative Example 3: Disruption of specific synergistic ratios among components (ratios too low) This comparative example provides a comparative preparation scheme with the following component ratio: 50 parts of a C3-C10 mixed fatty alcohol (n-butanol:isoamyl alcohol = 1:1), 5 parts of fatty acid methyl ester, 5 parts of methyl tert-butyl ether, 5 parts of dimethyl carbonate, 1 part of isoamyl nitrate, and 25 parts of -10# automotive diesel fuel. In this case, the mass ratio of methyl tert-butyl ether to dimethyl carbonate is 1:1, which is lower than the predetermined ratio range of this invention. The preparation process is as described in Example 1.

[0074] Comparative Example 4: Disruption of a specific stepped feeding process (one-pot method) The raw material composition and ratio of this comparative example are completely consistent with those of Example 1, but the preparation logic has been changed: all components, including C3-C10 mixed fatty alcohols, fatty acid methyl esters, methyl tert-butyl ether, dimethyl carbonate, diesel oil and combustion improver, are added into the reactor at one time, and the high-shear emulsifier (2500 s⁻¹) is turned on directly at room temperature and stirred continuously for 60 minutes.

[0075] Design objective: To verify whether performance degradation would occur due to intermolecular competitive adsorption or localized high temperatures if the stepwise process of "coupling first, then dissolving, then homogenizing, and finally adding combustion aid at low temperature" is not adopted.

[0076] Comparative Example 5: Deletion of fatty acid methyl esters (lack of lubrication and coupling) This comparative example provides a comparative preparation scheme with the following component ratios: 50 parts of C3-C10 mixed fatty alcohols, 0 parts of fatty acid methyl esters (without addition), 10 parts of methyl tert-butyl ether, 5 parts of dimethyl carbonate, 1 part of isoamyl nitrate, and 25 parts of -10# automotive diesel fuel. The preparation process is the same as in Example 1.

[0077] Design objective: To demonstrate that fatty acid methyl esters not only play a lubricating role in the system, but their long carbon chain structure also plays an indispensable "anchoring" role at the alcohol-oil interface.

[0078] Comparative Example 6: Incorrect timing of addition of the heat-sensitive component (added at high temperature) The raw material ratio and process steps (1)-(3) of this comparative example are the same as those of Example 1. However, in step (4), no cooling treatment is performed. Isoamyl nitrate is added directly during the process of generating mechanical heat by turning on the high shear emulsifier (the system temperature naturally rises to about 45℃-50℃).

[0079] Design purpose: To specifically verify the destructive effect of temperature on the activity of combustion improvers, thereby supporting the necessity of "adding below 30°C" in the process.

[0080] To visually demonstrate the superiority of the technical solution described in this invention and verify its resistance to phase separation and boundary lubrication under extremely high alcohol blending conditions, the additives obtained in Examples 1-8 and the control group obtained in Comparative Examples 1-6 were formulated into a new energy mixed fuel product in the same proportion (additive: methanol = 25:75 by weight) for ultimate pressure evaluation. Although the methanol content in this formulation is as high as 75%, the additive of this invention is rich in low-iodine-value long-chain fatty acid methyl esters (C16-C18), which can quickly form a high-strength anti-wear protective film on the high-pressure oil pump and cylinder wall, thereby effectively offsetting the risk of metal dry friction and corrosion caused by a large amount of methanol. At the same time, relying on the physical encapsulation and protection of isoamyl nitrate by the microemulsion system, a sufficient amount of highly active free radicals are released at the top dead center of compression, serving as a multi-point ignition source, forcibly enhancing the auto-ignition performance of the overall mixture and meeting the ignition requirements of the compression ignition engine. Subsequently, various indicators were tested according to the aforementioned "III. Test Methods and Evaluation Standards", and the summarized data are shown in Table 1: Table 1: Performance characteristics of the fuel products prepared in Examples 1-8 and Comparative Examples 1-6 In-depth analysis of the technical mechanism, through horizontal comparison and cross-validation of the data in Table 1: (1) Polar gradient synergistic effect - solving the problem of poor low-temperature phase separation and oil dissolving effect: Comparing Example 1 with Comparative Examples 1, 2 and 3, it can be seen that relying solely on C3-C10 mixed fatty alcohols and ether cosolvents cannot lock in a high proportion of methanol under extremely cold conditions.

[0081] Physical Mechanism: This invention successfully constructed a "polarity gradient buffer layer" ranging from highly polar (methanol) to moderately polar (DMC / MTBE) and then to non-polar (diesel) by limiting the mass ratio of methyl tert-butyl ether (MTBE) to dimethyl carbonate (DMC) to a specific range of 1.5:1 to 2.5:1. Conclusion: Although Comparative Examples 2 and 3 also added co-solvents, the imbalance in the ratio prevented the formation of a dense hydrogen-bonded coupling network. Example 1 showed a several-fold improvement in stability at -10°C; this non-linear performance leap demonstrates the significant synergistic effect of this specific ratio.

[0082] (2) Spatial hindrance and surface activity anchoring - solving poor lubrication and unstable emulsion: Comparative Example 1 with Examples 6 and 7 and Comparative Example 5, it can be seen that the combination of mixed C3-C10 fatty alcohols and fatty acid methyl esters is crucial.

[0083] Physical Mechanism: The combined use of n-butanol and isoamyl alcohol utilizes the combined steric hindrance caused by the difference in their branched structures, resulting in a narrower particle size distribution of the microemulsion particles. Simultaneously, the long carbon chains of fatty acid methyl esters act as "molecular anchors," with one end penetrating deep into the diesel phase and the other end associating with alcohol hydroxyl groups.

[0084] Conclusion: In Comparative Example 5, the viscosity dropped sharply to 1.45 mm² / s and the stability deteriorated after the methyl ester was removed, proving that fatty acid methyl esters are not only lubricants in this system, but also interfacial enhancers.

[0085] (3) Power retention and heat-sensitive component protection mechanism - solving the problem of low ignition point and power reduction: compared with Example 1 and Comparative Examples 4 and 6, this is the core embodiment of the inventiveness of the process of this invention.

[0086] Physical Mechanism: Isoamyl nitrate exhibits extremely high chemical reactivity but is highly sensitive to heat and shear forces. Comparative Example 4 employed a "one-pot" high-speed shearing process, where mechanical energy was converted into internal energy, leading to localized temperature increases and inducing premature autocatalytic decomposition of the nitrate ester components.

[0087] Conclusion: Example 1, through a step-by-step process of "first constructing a microemulsion system, and then adding it at a low speed after cooling to below 30°C in the final stage," maximized the preservation of the chemical potential energy of the combustion-supporting molecules. The measured cetane number increased from 40.3 in Comparative Example 4 to 49.5, and the bench fuel consumption reduction rate surged from 4.1% to 14.2%, which confirms the decisive contribution of the process flow of this invention to fuel power performance.

[0088] (4) Secondary benefits of environmental protection and emission reduction: As can be seen from the exhaust gas detection data, because the additive of the present invention achieves a uniform molecular-level distribution of methanol and diesel through polarity regulation, the combustion is more intense and complete after entering the cylinder, and the PM particulate matter reduction rate reaches 35.6%. This proves that the present invention achieves excellent environmental protection and emission reduction effects by optimizing combustion dynamics while improving power.

[0089] In the description of this specification, the references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0090] The above description is merely an example and illustration of the concept of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the concept of the invention or exceed the scope defined in the claims, they should all fall within the protection scope of the present invention.

Claims

1. An alcohol-based fuel additive, characterized in that, Based on parts by weight, it includes the following components: C3-C10 mixed fatty alcohols: 45-55 parts; Fatty acid methyl esters: 3-8 parts; Methyl tert-butyl ether: 8-12 parts; Isoamyl nitrate: 0.5-3 parts; Dimethyl carbonate: 4-6 parts; Diesel fuel: 20-30 parts; The mass ratio of the methyl tert-butyl ether to the dimethyl carbonate is 1.5:1 to 2.5:

1.

2. The alcohol-based fuel additive according to claim 1, characterized in that, Based on parts by weight, it includes the following components: C3-C10 mixed fatty alcohols: 50.0 parts; Fatty acid methyl esters: 5.0 parts; Methyl tert-butyl ether: 10.0 parts; Isoamyl nitrate: 1.0 part; Dimethyl carbonate: 5.0 parts; Diesel fuel: 25.0 parts.

3. The alcohol-based fuel additive according to claim 1, characterized in that, The C3-C10 mixed fatty alcohols are selected from at least one of straight-chain fatty alcohols or branched fatty alcohols having C3 to C10 carbon atoms; the C3-C10 mixed fatty alcohols contain n-butanol and isoamyl alcohol in a mass ratio of 0.8:1 to 2.0:

1.

4. The alcohol-based fuel additive according to claim 1, characterized in that, The fatty acid methyl ester has a carbon chain length of C16 to C18, and the iodine value of the fatty acid methyl ester is not greater than 120 g I2 / 100g.

5. The alcohol-based fuel additive according to claim 1, characterized in that, The diesel fuel has a cetane number of not less than 51 and a pour point between -15°C and 0°C.

6. A method for preparing an alcohol-based fuel additive as described in any one of claims 1-5, characterized in that, Includes the following steps: (1) Premixing: The C3-C10 mixed fatty alcohol and the fatty acid methyl ester are mixed and stirred to obtain a premixed solution; (2) Miscibility treatment: The methyl tert-butyl ether and the dimethyl carbonate are mixed and then added to the premixed solution to obtain a composite solubilizing system; (3) Homogeneous dispersion: The diesel oil is added to the composite cosolvent system for shear emulsification, and then the isoamyl nitrate is added to obtain the alcohol-based fuel additive.

7. The preparation method according to claim 6, characterized in that, The entire process from step (1) to step (3) is carried out under nitrogen protection, and the system temperature before adding the isoamyl nitrate in step (3) is not higher than 30°C.

8. A hybrid new energy alcohol-based fuel, characterized in that, The product comprises, by weight: 72.5-84.5 parts of methanol; and 15.5-28 parts of alcohol-based fuel additive as described in any one of claims 1-5.

9. The hybrid new energy alcohol-based fuel according to claim 8, characterized in that, The purity of the methanol is not less than 99.5 wt%, and the water content in the methanol is not more than 0.1 wt%.

10. An alcohol-based fuel additive as described in any one of claims 1-5, or the application of a blended new energy alcohol-based fuel as described in claim 8 or 9 in a compression ignition engine fuel.

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