Preparation method and application of ternary copolymerized EVA diesel pour point depressant

Abstract

The application provides a preparation method and application of a ternary copolymer EVA diesel pour point depressant, and belongs to the technical field of petroleum chemical additives. The ternary copolymer EVA diesel pour point depressant with an ethylene content of 60% to 65% is successfully prepared by introducing a third monomer into EVA, using an alkane compound as a solvent, adopting a medium-pressure polymerization process, and in a way of step feeding and continuously dropping the remaining raw materials. The introduction of the third monomer provides suitable polar groups and steric hindrance effects, effectively protects ester groups and improves the dispersibility of the pour point depressant in diesel. The ternary copolymer EVA diesel pour point depressant has a significant pour point depression effect, can reduce the diesel condensation point by 15 to 23 DEG C, and can reduce the cold filter plugging point by 8 to 14 DEG C. Compared with the existing high-pressure process, the application significantly reduces the equipment investment and energy consumption, the process is simple and easy to industrialize, provides an economic and efficient scheme for improving the low-temperature fluidity of diesel, and has a good popularization and application prospect.

Description

Technical Field

[0001] This invention relates to the field of petrochemical additives technology, specifically to a method for preparing and applying a ternary copolymer EVA-based diesel pour point depressant with an ethylene content of 60%~65%. Background Technology

[0002] Diesel fuel serves as an important power fuel in many areas of production and daily life. However, it is prone to wax crystal precipitation at low temperatures. When a large number of wax crystals form and interconnect to create a network structure, the diesel fuel loses its fluidity, i.e., it solidifies, affecting the normal operation of the engine and causing great inconvenience to production and daily life. To solve this problem, pour point depressants (PPDs) are usually added to diesel fuel to lower its pour point and cold filter plugging point, thereby improving its low-temperature fluidity.

[0003] Currently, pour point depressants are mainly classified into the following categories: surfactant-type, comb-like polymer-type, olefin-unsaturated ester-type, nitrogen-containing type, alkyl aromatic type, and compound type. There are many types of diesel pour point depressants on the market, but some products suffer from complex preparation processes, high costs, and unsatisfactory pour point depressing effects. Among them, ethylene-vinyl acetate (EVA) pour point depressants are widely used, but their preparation process typically involves reaction pressures exceeding 100 MPa and reaction temperatures of 100–200 °C. This process requires significant equipment investment, consumes a lot of energy, and causes severe equipment wear, resulting in high production costs.

[0004] Therefore, this invention has developed an ethylene-vinyl acetate diesel pour point depressant with a simple preparation process, low cost, and good pour point depressing effect through medium-pressure polymerization. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a method for preparing and applying a ternary copolymer EVA-based diesel pour point depressant with an ethylene content of 60%~65%. This invention uses vinyl acetate, ethylene, and a third monomer as reactants, and prepares the ternary copolymer EVA-based diesel pour point depressant through a medium-pressure polymerization process. This method is simple, low-cost, and the prepared ternary copolymer EVA-based diesel pour point depressant can effectively reduce the pour point and cold filter plugging point of diesel fuel, solving the problems of complex processes, high costs, and unsatisfactory pour point depressant effects in existing technologies.

[0006] To achieve the above objectives, the specific technical solution of the present invention is as follows:

[0007] In a first aspect, the present invention provides a method for preparing a ternary copolymer EVA-based diesel pour point depressant, comprising the following steps:

[0008] All alkane solvents, along with a portion of vinyl acetate and a portion of the third monomer, are added to a reaction vessel for premixing; the third monomer includes at least one of vinyl neodecanoate, vinyl neononanoate, octene, and methyl acrylate.

[0009] Remove the air from the reactor, add some of the initiator to the reactor, mix well, and then introduce ethylene to raise the system pressure to 8~13 MPa;

[0010] The temperature is raised to 80~100 ℃ to carry out the polymerization reaction, and the remaining vinyl acetate, the third monomer and the initiator are continuously added dropwise while maintaining the reaction temperature at 80~100 ℃ and the pressure at 8~13 MPa.

[0011] After the addition is complete, the reaction is continued at the same temperature and pressure for 1-4 hours to obtain a ternary copolymer EVA-type diesel pour point depressant.

[0012] This invention employs a medium-pressure polymerization process, using a combination of batch feeding and continuous dripping of residual raw materials to successfully prepare ternary copolymer EVA compounds with an ethylene content of 60%–65%, which significantly reduce the pour point and cold filter plugging point of diesel fuel. A single-batch feeding method would result in a ternary copolymer EVA product with a high molecular weight, low melt index, and poor solubility, hindering dispersion in diesel fuel. Furthermore, vinyl acetate exhibits high reactivity in the early stages of polymerization; a single-batch feeding would lead to a low ethylene content in the resulting ternary copolymer EVA product. This invention utilizes a subsequent continuous, slow dripping method to allow more ethylene to participate in the reaction, while simultaneously balancing the product's molecular chain length with the number of polar groups (e.g., ester groups), thereby significantly improving the product's pour point depressant effect.

[0013] Furthermore, the third monomer is vinyl neodecanoate.

[0014] Furthermore, the alkane solvents include, but are not limited to, one or more of the following: n-hexane, cyclohexane, n-heptane, n-decane, No. 120 solvent oil (mainly C6-C7 hydrocarbons), and No. 6 extraction solvent oil (mainly hexane isomers).

[0015] Furthermore, the alkane solvent is cyclohexane or n-hexane.

[0016] Furthermore, the molar ratio of the total amount of ethylene to the total amount of vinyl acetate is (5~10):1; the molar ratio of the total amount of the third monomer to the total amount of vinyl acetate is 1:(30~50).

[0017] Furthermore, the vinyl acetate in the aforementioned portion accounts for 40% to 60% of the total amount of vinyl acetate; the third monomer in the aforementioned portion accounts for 30% to 50% of the total amount of the third monomer; and the initiator in the aforementioned portion accounts for 40% to 60% of the total amount of the initiator.

[0018] Furthermore, the molar ratio of the total amount of alkane solvent to the total amount of vinyl acetate is (3~8):1.

[0019] Furthermore, the total amount of the initiator is 0.001% to 0.02% of the total mass of ethylene and vinyl acetate.

[0020] Further, the initiator includes at least one of organic peroxide initiators and azo initiators; wherein the organic peroxide initiator includes, but is not limited to, at least one of benzoyl peroxide (BPO), dilauryl peroxide (LPO), and tert-butyl peroxyneodecanate (TBPD); and the azo initiator includes, but is not limited to, at least one of dimethyl azobisisobutyrate (AIBME) and azobisisobutyronitrile (AIBN).

[0021] Further, ethylene is introduced to raise the system pressure to 8-13 MPa, and then ethylene is continued to be introduced to maintain the pressure at 8-13 MPa.

[0022] Furthermore, the remaining vinyl acetate, third monomer, and initiator should be added dropwise within 1 to 5 hours.

[0023] Secondly, the present invention provides a ternary copolymer EVA-based diesel pour point depressant prepared by the aforementioned preparation method. The ternary copolymer EVA-based diesel pour point depressant contains 60% to 65% ethylene by mass.

[0024] Thirdly, the present invention provides a method for applying the ternary copolymer EVA-type diesel pour point depressant in reducing the pour point and cold filter plugging point of diesel fuel, comprising the following steps:

[0025] The ternary copolymer EVA-type diesel pour point depressant was added to diesel fuel and ultrasonically dispersed in diesel fuel at 40-60 °C for 20-40 min.

[0026] Furthermore, the amount of the ternary copolymer EVA-type diesel pour point depressant added is 0.05wt%~0.25wt%.

[0027] Furthermore, the diesel fuel is commercially available #0 diesel fuel.

[0028] Compared with the prior art, the advantages of the present invention are:

[0029] (1) The preparation method of the ternary copolymer EVA diesel pour point depressant provided by the present invention is efficient, simple and easy to operate, and the raw materials used are low in cost, making it suitable for large-scale industrial production. The ternary copolymer EVA diesel pour point depressant prepared by this method has good dispersibility in diesel and can be well mixed with diesel.

[0030] (2) In the ethylene-vinyl acetate-vinyl neodecanoate ternary copolymer EVA diesel pour point depressant provided by the present invention, both vinyl acetate and vinyl neodecanoate can provide corresponding polar groups. Vinyl neodecanoate can also protect the integrity of the ester groups in the molecular chain through steric hindrance, thus ensuring the dispersibility of the pour point depressant in diesel. The ternary copolymer EVA diesel pour point depressant molecules of the present invention are adsorbed onto wax crystals through polar parts, while the long-chain alkane parts (ethylene segments) are fully extended in the oil phase. Through steric hindrance, the wax crystals are prevented from approaching each other and forming a three-dimensional network structure, effectively reducing the pour point and cold filter plugging point of diesel, significantly improving the fluidity of diesel in low-temperature environments, and ensuring the normal operation of the engine.

[0031] (3) When the ternary copolymer EVA diesel pour point depressant provided by the present invention is applied, it can reduce the pour point of diesel by 15-23 ℃ and the cold filter plugging point by 8-14 ℃ simply by ultrasonically dispersing it in diesel. Detailed Implementation

[0032] To enable those skilled in the art to clearly and completely understand the technical solution of the present invention, the present invention will be further described in detail below with reference to embodiments. Obviously, the embodiments described herein are only for explaining the present invention and are not intended to limit the scope of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0033] This invention provides a method for preparing a ternary copolymer EVA-based diesel pour point depressant, comprising the following steps:

[0034] All alkane solvents, along with a portion of vinyl acetate and a portion of the third monomer, are added to a reaction vessel for premixing; the third monomer includes at least one of vinyl neodecanoate, vinyl neononanoate, octene, and methyl acrylate.

[0035] Remove the air from the reactor, add some of the initiator to the reactor, mix well, and then introduce ethylene to raise the system pressure to 8~13 MPa;

[0036] The temperature is raised to 80~100 ℃ to carry out the polymerization reaction, and the remaining vinyl acetate, the third monomer and the initiator are continuously added dropwise while maintaining the reaction temperature at 80~100 ℃ and the pressure at 8~13 MPa.

[0037] After the addition is complete, the reaction is continued at the same temperature and pressure for 1-4 hours to obtain a ternary copolymer EVA-type diesel pour point depressant.

[0038] In some examples, the alkane solvents include, but are not limited to, one or more of the following: n-hexane, cyclohexane, n-heptane, n-decane, No. 120 solvent oil (mainly C6-C7 hydrocarbons), and No. 6 extraction solvent oil (mainly hexane isomers).

[0039] In some examples, the molar ratio of the total amount of ethylene to the total amount of vinyl acetate is (5~10):1; the molar ratio of the total amount of the third monomer to the total amount of vinyl acetate is 1:(30~50); the molar ratio of the total amount of alkane solvent to the total amount of vinyl acetate is (3~8):1; and the total amount of initiator is 0.001%~0.02% of the total mass of ethylene and vinyl acetate.

[0040] In some examples, the vinyl acetate portion accounts for 40% to 60% of the total vinyl acetate content; the third monomer portion accounts for 30% to 50% of the total third monomer content; and the initiator portion accounts for 40% to 60% of the total initiator content.

[0041] In some examples, the initiator includes at least one of organic peroxide initiators and azo initiators; wherein the organic peroxide initiator includes, but is not limited to, at least one of benzoyl peroxide (BPO), dilauryl peroxide (LPO), and tert-butyl peroxyneodecanate (TBPD); and the azo initiator includes, but is not limited to, at least one of dimethyl azobisisobutyrate (AIBME) and azobisisobutyronitrile (AIBN).

[0042] In some examples, ethylene is introduced to raise the system pressure to 8-13 MPa, and then ethylene is continued to be introduced to maintain the pressure at 8-13 MPa.

[0043] In some examples, the remaining vinyl acetate, third monomer, and initiator are added dropwise within 1 to 5 hours.

[0044] In some examples, the ethylene content in the ternary copolymer EVA-type diesel pour point depressant is 60% to 65% by mass.

[0045] All raw materials used in the following examples are commercially available products.

[0046] The diesel pour point test method described in the following examples is determined according to the national standard GB / T 510-2018 "Determination of Pour Point of Petroleum Products"; the diesel cold filter plugging point is determined according to the national standard NB / SH / T 0248-2019 "Determination of Cold Filter Plugging Point of Diesel and Domestic Heating Oil".

[0047] Example 1

[0048] A ternary copolymer EVA-based diesel pour point depressant is prepared using the following steps:

[0049] 1. Raw material preparation

[0050] Prepare all raw materials according to the following formula: the total amount of ethylene to vinyl acetate is 8.4:1; the total amount of neodecanoate to vinyl acetate is 1:35; the total amount of cyclohexane to vinyl acetate is 5.55:1; and the total amount of benzoyl peroxide is 0.01% of the total mass of ethylene and vinyl acetate.

[0051] 2. Hybridization and Supercharging

[0052] Add all of the cyclohexane, 40% of vinyl acetate, and 50% of vinyl neodecanoate to a high-pressure reactor and start stirring for premixing. Replace the reactor with nitrogen (repeatedly pressurize and depressurize at least 3 times) to remove air. Then, add 40% benzoyl peroxide, mix well, and then introduce ethylene gas to raise the system pressure to 11 MPa.

[0053] 3. Polymerization reaction

[0054] The reaction system was heated to 85 °C and maintained at this temperature. The reaction pressure was stabilized at 11 MPa by continuously introducing ethylene. Under these conditions, the remaining vinyl acetate, vinyl decanoate, and benzoyl peroxide were slowly and uniformly added to the reaction system over 2 hours using a constant pressure drop pump. After the addition was complete, the reaction was continued at the same temperature and pressure for 4 hours.

[0055] 4. Post-processing

[0056] After the reaction is complete, the reaction system is cooled to room temperature and the residual pressure is slowly released. The reaction product is taken out and dried in a vacuum oven at 120°C to remove the solvent cyclohexane and unreacted residual monomers, finally yielding a white waxy ethylene-vinyl acetate-neodecanedyl acetate terpolymer EVA-type diesel pour point depressant.

[0057] Example 2

[0058] A ternary copolymer EVA-based diesel pour point depressant is prepared using the following steps:

[0059] 1. Raw material preparation

[0060] Prepare the raw materials according to the following formula: the total amount of ethylene to vinyl acetate is 7.4:1, the total amount of neodecanoate to vinyl acetate is 1:40, the total amount of n-hexane to vinyl acetate is 3.5:1, and the total amount of dilauryl peroxide is 0.006% of the total mass of ethylene and vinyl acetate.

[0061] 2. Hybridization and Supercharging

[0062] Add all of the n-hexane, 50% of the vinyl acetate, and 40% of the neodecanoate to a high-pressure reactor and start stirring for premixing. Pressurize and depressurize the reactor with nitrogen more than three times to completely remove air. Then, add 50% of dilauryl peroxide, mix well, and then introduce ethylene gas to raise the system pressure to 10.5 MPa.

[0063] 3. Polymerization reaction

[0064] The reaction system was heated to 80 °C and maintained at this temperature. The reaction pressure was stabilized at 10.5 MPa by continuously introducing ethylene. Under these conditions, the remaining vinyl acetate, vinyl neodecanoate, and dilauryl peroxide were slowly and uniformly added to the reaction system over 2 hours using a constant pressure dropping pump. After the addition was completed, the reaction was continued at the same temperature and pressure for 4 hours.

[0065] 4. Post-processing

[0066] After the reaction is complete, the reaction system is cooled to room temperature and the residual pressure is slowly released. The reaction product is taken out and dried in a vacuum oven at 120°C to remove the solvent n-hexane and unreacted residual monomers, finally yielding a white waxy ethylene-vinyl acetate-neodecanedolate terpolymer EVA-type diesel pour point depressant.

[0067] Example 3

[0068] A ternary copolymer EVA-based diesel pour point depressant is prepared using the following steps:

[0069] 1. Raw material preparation

[0070] Prepare the raw materials according to the following formula: the total amount of ethylene to vinyl acetate is 6.65:1; the total amount of neodecanoate to vinyl acetate is 1:35; the total amount of cyclohexane to vinyl acetate is 7.55:1; and the total amount of dimethyl azobisisobutyrate is 0.004% of the total mass of ethylene and vinyl acetate.

[0071] 2. Hybridization and Supercharging

[0072] Add all of the cyclohexane, 60% of the vinyl acetate, and 30% of the neodecanoate to a high-pressure reactor and start stirring for premixing. Replace the reactor with nitrogen (repeatedly pressurize and depressurize at least 3 times) to remove air. Then, add 60% of the dimethyl azobisisobutyrate and mix thoroughly. Then, introduce ethylene gas to raise the system pressure to 9.5 MPa.

[0073] 3. Polymerization reaction

[0074] The reaction system was heated to 90 °C and maintained at this temperature. The reaction pressure was stabilized at 9.5 MPa by continuously introducing ethylene. Under these conditions, the remaining vinyl acetate, vinyl neodecanoate, and dimethyl azobisisobutyrate were slowly and uniformly added to the reaction system over 2 hours using a constant pressure drop pump. After the addition was complete, the reaction was continued at the same temperature and pressure for another 4 hours.

[0075] 4. Post-processing

[0076] After the reaction is complete, the reaction system is cooled to room temperature and the residual pressure is slowly released. The reaction product is taken out and dried in a vacuum oven at 120°C to remove the solvent cyclohexane and unreacted residual monomers, finally yielding a white waxy ethylene-vinyl acetate-neodecanedyl acetate terpolymer EVA-type diesel pour point depressant.

[0077] Example 4

[0078] A ternary copolymer EVA-based diesel pour point depressant is prepared using the following steps:

[0079] 1. Raw material preparation

[0080] Prepare the raw materials according to the following formula: the total amount of ethylene to vinyl acetate is 10:1, the total amount of neodecanoate to vinyl acetate is 1:30, the total amount of cyclohexane to vinyl acetate is 7.55:1, and the total amount of azobisisobutyronitrile is 0.008% of the total mass of ethylene and vinyl acetate.

[0081] 2. Hybridization and Supercharging

[0082] Add all of the cyclohexane, 40% of the vinyl acetate, and 50% of the neodecanoate to a high-pressure reactor and start stirring for premixing. Replace the reactor with nitrogen (repeatedly pressurize and depressurize at least 3 times) to remove air. Then, add 60% of the azobisisobutyronitrile, mix well, and then introduce ethylene gas to raise the system pressure to 13 MPa.

[0083] 3. Polymerization reaction

[0084] The reaction system was heated to 100 °C and maintained at this temperature. The reaction pressure was stabilized at 13 MPa by continuously introducing ethylene. Under these conditions, the remaining vinyl acetate, vinyl decanoate, and azobisisobutyronitrile were slowly and uniformly added to the reaction system over 2 hours using a constant pressure dropping pump. After the addition was complete, the reaction was continued at the same temperature and pressure for 4 hours.

[0085] 4. Post-processing

[0086] After the reaction is complete, the reaction system is cooled to room temperature and the residual pressure is slowly released. The reaction product is taken out and dried in a vacuum oven at 120°C to remove the solvent cyclohexane and unreacted residual monomers, finally yielding a white waxy ethylene-vinyl acetate-neodecanedyl acetate terpolymer EVA-type diesel pour point depressant.

[0087] Comparative Example 1

[0088] A ternary copolymer EVA-based diesel pour point depressant is prepared using the following steps:

[0089] 1. Raw material preparation

[0090] Prepare all raw materials according to the following formula: the total amount of ethylene to vinyl acetate is 8.4:1; the total amount of neononanoate to vinyl acetate is 1:35; the total amount of cyclohexane to vinyl acetate is 5.55:1; and the total amount of benzoyl peroxide is 0.01% of the total mass of ethylene and vinyl acetate.

[0091] 2. Hybridization and Supercharging

[0092] Add all of the cyclohexane, 40% of vinyl acetate, and 50% of vinyl nonanoate to a high-pressure reactor and start stirring for premixing. Replace the reactor with nitrogen (repeatedly pressurize and depressurize at least 3 times) to remove air. Then, add 40% benzoyl peroxide, mix well, and then introduce ethylene gas to raise the system pressure to 11 MPa.

[0093] 3. Polymerization reaction

[0094] The reaction system was heated to 85 °C and maintained at this temperature. The reaction pressure was stabilized at 11 MPa by continuously introducing ethylene. Under these conditions, the remaining vinyl acetate, vinyl nonanoate, and benzoyl peroxide were slowly and uniformly added to the reaction system over 2 hours using a constant pressure drop pump. After the addition was complete, the reaction was continued at the same temperature and pressure for 4 hours.

[0095] 4. Post-processing

[0096] After the reaction is complete, the reaction system is cooled to room temperature and the residual pressure is slowly released. The reaction product is then removed and dried in a vacuum oven at 120°C to remove the solvent cyclohexane and unreacted residual monomers, finally yielding a white, waxy ethylene-vinyl acetate-vinyl neononanoate terpolymer EVA-type diesel pour point depressant.

[0097] Comparative Example 2

[0098] A ternary copolymer EVA-based diesel pour point depressant is prepared using the following steps:

[0099] 1. Raw material preparation

[0100] Prepare the raw materials according to the following formula: the total amount of ethylene to vinyl acetate is 7.4:1, the total amount of octene to vinyl acetate is 1:40, the total amount of n-hexane to vinyl acetate is 3.5:1, and the total amount of dilauryl peroxide is 0.006% of the total mass of ethylene and vinyl acetate.

[0101] 2. Hybridization and Supercharging

[0102] Add all of the n-hexane, 50% of the vinyl acetate, and 40% of the octene to a high-pressure reactor and start stirring for premixing. Pressurize and depressurize the reactor with nitrogen more than three times to completely remove air. Then, add 50% of dilauryl peroxide, mix well, and then introduce ethylene gas to raise the system pressure to 10.5 MPa.

[0103] 3. Polymerization reaction

[0104] The reaction system was heated to 80 °C and maintained at this temperature. The reaction pressure was stabilized at 10.5 MPa by continuously introducing ethylene. Under these conditions, the remaining vinyl acetate, octene, and dilauryl peroxide were slowly and uniformly added to the reaction system over 2 hours using a constant pressure dropping pump. After the addition was completed, the reaction was continued at the same temperature and pressure for 4 hours.

[0105] 4. Post-processing

[0106] After the reaction is complete, the reaction system is cooled to room temperature and the residual pressure is slowly released. The reaction product is taken out and placed in a vacuum oven at 120°C for drying to remove the solvent n-hexane and unreacted residual monomers, finally yielding a white waxy ethylene-vinyl acetate-octene terpolymer EVA-type diesel pour point depressant.

[0107] Comparative Example 3

[0108] A ternary copolymer EVA-based diesel pour point depressant is prepared using the following steps:

[0109] 1. Raw material preparation

[0110] Prepare the raw materials according to the following formula: the total amount of ethylene to vinyl acetate is 6.65:1; the total amount of methyl acrylate to vinyl acetate is 1:35; the total amount of cyclohexane to vinyl acetate is 7.55:1; and the total amount of dimethyl azobisisobutyrate is 0.004% of the total mass of ethylene and vinyl acetate.

[0111] 2. Hybridization and Supercharging

[0112] Add all of the cyclohexane, 60% of the vinyl acetate, and 30% of the methyl acrylate to a high-pressure reactor and start stirring for premixing. Replace the reactor with nitrogen (repeatedly pressurize and depressurize at least 3 times) to remove air. Then, add 60% of the dimethyl azobisisobutyrate and mix thoroughly. Then, introduce ethylene gas to raise the system pressure to 9.5 MPa.

[0113] 3. Polymerization reaction

[0114] The reaction system was heated to 90 °C and maintained at this temperature. The reaction pressure was stabilized at 9.5 MPa by continuously introducing ethylene. Under these conditions, the remaining vinyl acetate, methyl acrylate, and dimethyl azobisisobutyrate were slowly and uniformly added to the reaction system over 2 hours using a constant pressure dropping pump. After the addition was complete, the reaction was continued at the same temperature and pressure for another 4 hours.

[0115] 4. Post-processing

[0116] After the reaction is complete, the reaction system is cooled to room temperature and the residual pressure is slowly released. The reaction product is taken out and dried in a vacuum oven at 120°C to remove the solvent cyclohexane and unreacted residual monomers, finally yielding a white waxy ethylene-vinyl acetate-methyl acrylate terpolymer EVA-type diesel pour point depressant.

[0117] Comparative Example 4

[0118] A ternary copolymer EVA-based diesel pour point depressant is prepared using the following steps:

[0119] 1. Raw material preparation

[0120] Prepare all raw materials according to the following formula: the total amount of ethylene to the total amount of vinyl acetate is 4.5:1; the total amount of neodecanoate to the total amount of vinyl acetate is 1:35; the total amount of cyclohexane to the total amount of vinyl acetate is 5.55:1; and the total amount of benzoyl peroxide is 0.01% of the total mass of ethylene and vinyl acetate.

[0121] 2. Hybridization and Supercharging

[0122] Add all of the cyclohexane, 40% of the vinyl acetate, and 50% of the neodecanoate to a high-pressure reactor and start stirring for premixing. Replace the reactor with nitrogen (repeatedly pressurize and depressurize at least 3 times) to remove air. Then, add 40% of benzoyl peroxide, mix well, and then introduce ethylene gas to raise the system pressure to 7.5 MPa.

[0123] 3. Polymerization reaction

[0124] The reaction system was heated to 85 °C and maintained at this temperature. The reaction pressure was stabilized at 8 MPa by continuously introducing ethylene. Under these conditions, the remaining vinyl acetate, vinyl neodecanoate, and benzoyl peroxide were slowly and uniformly added to the reaction system over 2 hours using a constant pressure dropping pump. After the addition was completed, the reaction was continued at the same temperature and pressure for 4 hours.

[0125] 4. Post-processing

[0126] After the reaction is complete, the reaction system is cooled to room temperature and the residual pressure is slowly released. The reaction product is taken out and dried in a vacuum oven at 120°C to remove the solvent cyclohexane and unreacted residual monomers, finally yielding a white waxy ethylene-vinyl acetate-neodecanedyl acetate terpolymer EVA-type diesel pour point depressant.

[0127] Comparative Example 5

[0128] A ternary copolymer EVA-based diesel pour point depressant is prepared using the following steps:

[0129] 1. Raw material preparation

[0130] Prepare all raw materials according to the following formula: the total amount of ethylene to vinyl acetate is 5.5:1; the total amount of neodecanoate to vinyl acetate is 1:20; the total amount of cyclohexane to vinyl acetate is 5.55:1; and the total amount of benzoyl peroxide is 0.01% of the total mass of ethylene and vinyl acetate.

[0131] 2. Hybridization and Supercharging

[0132] Add all of the cyclohexane, 40% of vinyl acetate, and 50% of vinyl neodecanoate to a high-pressure reactor and start stirring for premixing. Replace the reactor with nitrogen (repeatedly pressurize and depressurize at least 3 times) to remove air. Then, add 40% benzoyl peroxide, mix well, and then introduce ethylene gas to raise the system pressure to 8 MPa.

[0133] 3. Polymerization reaction

[0134] The reaction system was heated to 85 °C and maintained at this temperature. The reaction pressure was stabilized at 13 MPa by continuously introducing ethylene. Under these conditions, the remaining vinyl acetate, vinyl neodecanoate, and benzoyl peroxide were slowly and uniformly added to the reaction system over 2 hours using a constant pressure drop pump. After the addition was complete, the reaction was continued at the same temperature and pressure for another 4 hours.

[0135] 4. Post-processing

[0136] After the reaction was completed, the reaction system was cooled to room temperature, and the residual pressure was slowly released. The reaction product was then removed and dried in a vacuum oven at 120°C to remove the solvent cyclohexane and unreacted residual monomers, finally yielding a white, waxy ethylene-vinyl acetate-neodecanedyl acetate terpolymer EVA-based diesel fuel pour point depressant.

[0137] The ternary copolymer EVA-based diesel pour point depressants prepared in Examples 1-4 and Comparative Examples 1-5 were added to commercially available 0# diesel (mass ratio 1:400), and after being mixed and stirred evenly at 50 °C, ultrasonically dispersed for 25 min. The pour point and cold filter plugging point of the diesel were then tested, and the results are as follows:

[0138]

[0139] As can be seen from the above, this invention employs a medium-pressure polymerization process (8~13 MPa), using ethylene, vinyl acetate, and a third monomer as comonomers. In cyclohexane or n-hexane solvent, through stepwise feeding and continuous dropwise addition of the remaining raw materials, a ternary copolymer EVA-type pour point depressant with an ethylene content of 60%~65% was successfully prepared. Compared with existing high-pressure (>100 MPa) processes, this invention significantly reduces equipment investment and energy consumption, and the process is simple and easy for industrial production. The introduction of the third monomer in this invention provides suitable polar groups and steric hindrance effects, effectively protecting the ester groups and improving the dispersibility of the pour point depressant in diesel fuel. Experimental results show that adding 0.25 wt% of the ternary copolymer EVA-type pour point depressant of this invention to 0# diesel fuel can lower the diesel fuel's pour point by 15~23 °C and the cold filter plugging point by 8~14 °C, demonstrating a significant pour point depressant effect. Furthermore, when vinyl decanoate is used as the third monomer, the pour point depressant effect is significantly better than that of vinyl nonanoate, octene, or methyl acrylate. This invention provides an economical, efficient, and single-component solution for improving the low-temperature fluidity of diesel fuel, which can achieve excellent pour point depressing effects and has good prospects for widespread application.

[0140] The above detailed embodiments describe the implementation of the present invention; however, the present invention is not limited to the specific details described in the above embodiments. Within the scope of the claims and technical concept of the present invention, various simple modifications and changes can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

Claims

1. A method for preparing a ternary copolymer EVA-based diesel pour point depressant, characterized in that, Includes the following steps: All alkane solvents, along with a portion of vinyl acetate and a portion of a third monomer, are added to a reaction vessel for premixing; the third monomer includes at least one of vinyl neodecanoate, vinyl neononanoate, octene, and methyl acrylate. Remove the air from the reactor, add some of the initiator to the reactor, mix well, and then introduce ethylene to raise the system pressure to 8~13 MPa; The temperature is raised to 80~100 ℃ to carry out the polymerization reaction, and the remaining vinyl acetate, the third monomer and the initiator are continuously added dropwise while maintaining the reaction temperature at 80~100 ℃ and the pressure at 8~13 MPa. After the addition is complete, the reaction is continued at the same temperature and pressure for 1-4 hours to obtain a ternary copolymer EVA-type diesel pour point depressant.

2. The preparation method of a ternary copolymer EVA-based diesel pour point depressant according to claim 1, characterized in that, The alkane solvents include, but are not limited to, one or more of the following: n-hexane, cyclohexane, n-heptane, n-decane, No. 120 solvent oil, and No. 6 extraction solvent oil.

3. The preparation method of a ternary copolymer EVA-based diesel pour point depressant according to claim 2, characterized in that, The alkane solvent is n-hexane or cyclohexane.

4. The preparation method of a ternary copolymer EVA-based diesel pour point depressant according to claim 1, characterized in that, The molar ratio of the total amount of ethylene to the total amount of vinyl acetate is (5~10):1; the molar ratio of the total amount of the third monomer to the total amount of vinyl acetate is 1:(30~50); the total amount of the initiator is 0.001%~0.02% of the total mass of ethylene and vinyl acetate.

5. The preparation method of a ternary copolymer EVA-based diesel pour point depressant according to claim 4, characterized in that, The vinyl acetate in the aforementioned portion accounts for 40% to 60% of the total vinyl acetate content; the third monomer in the aforementioned portion accounts for 30% to 50% of the total third monomer content; and the initiator in the aforementioned portion accounts for 40% to 60% of the total initiator content.

6. The preparation method of a ternary copolymer EVA-based diesel pour point depressant according to claim 4, characterized in that, The initiator includes at least one of organic peroxide initiators and azo initiators.

7. The preparation method of a ternary copolymer EVA-based diesel pour point depressant according to claim 1, characterized in that, The remaining vinyl acetate, third monomer, and initiator were added dropwise continuously over a period of 1–5 hours.

8. A ternary copolymer EVA-based diesel pour point depressant prepared by the preparation method according to any one of claims 1-7, characterized in that, The ethylene content in the ternary copolymer EVA-type diesel pour point depressant is 60%~65% by mass.

9. The method of applying the ternary copolymer EVA-type diesel pour point depressant according to claim 8 in reducing the pour point and cold filter plugging point of diesel fuel, characterized in that, include: The ternary copolymer EVA-type diesel pour point depressant was added to diesel fuel and ultrasonically dispersed in diesel fuel at 40-60 °C for 20-40 min.

10. The application method according to claim 9, characterized in that, The amount of the ternary copolymer EVA-type diesel pour point depressant added is 0.05wt%~0.25wt%.

Images