Environment-friendly crude oil pour point depressant as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of biomass energy additives, and particularly relates to an environment-friendly crude oil pour point depressant and a preparation method and application thereof. According to the crude oil pour point depressant product disclosed by the invention, a fumaric acid and high-carbon alcohol ester polymer formed by esterification reaction of fumaric acid and high-carbon alcohol ester is taken as a basis, and performance optimization is carried out by mixing and adding a polymer formed by free radical polymerization of glycidyl methacrylate and norbornene dicarboxylic anhydride; the glycidyl methacrylate-norbornene dicarboxylic acid anhydride polymer and the fumaric acid high-carbon alcohol ester polymer are mixed to form the required crude oil pour point depressant, and the condensation point, the cold filter plugging point and the viscosity of a crude oil product can be effectively improved by utilizing the synergistic interaction effect of the glycidyl methacrylate-norbornene dicarboxylic acid anhydride polymer on the fumaric acid high-carbon alcohol ester polymer, so that the low-temperature transportation and application performance of the crude oil product is further enhanced.

Description

Technical Field

[0001] This invention belongs to the field of biomass energy additive technology, specifically relating to an environmentally friendly crude oil pour point depressant and its preparation method and application. Background Technology

[0002] Energy is essential for human survival and development, and petroleum, obtained from crude oil processing, is a vital component of human production and daily life. Therefore, the extraction, transportation, and storage of crude oil are particularly important. However, the high wax content in crude oil leads to its high pour point and viscosity, ultimately causing it to lose its fluidity and solidify on the pipe walls. This results in difficulties in oil extraction, low efficiency, and transportation, posing significant challenges to crude oil extraction and transportation.

[0003] Pour point depressants, as commonly used chemical additives, are widely used in crude oil extraction and transportation to effectively improve crude oil fluidity and reduce transportation costs and risks. Commonly used crude oil pour point depressants mainly include ethylene-vinyl acetate copolymers, styrene-maleic anhydride copolymers, and acrylate polymers. The addition of these depressants effectively improves the low-temperature fluidity of crude oil. However, a common drawback of many currently used crude oil pour point depressants is their inability to disperse quickly and effectively in crude oil while ensuring efficiency, resulting in relatively high dosages and impacting environmental performance. There is a growing demand in this field for the development of more adaptable crude oil pour point depressant products with superior pour point depressing effects. Summary of the Invention

[0004] Therefore, the purpose of this invention is to provide an environmentally friendly crude oil pour point depressant, which has better pour point depressing effect and application performance; The second objective of this invention is to provide a method for preparing and applying the above-mentioned environmentally friendly crude oil pour point depressant.

[0005] To solve the above-mentioned technical problems, the present invention provides an environmentally friendly crude oil pour point depressant, wherein the crude oil pour point depressant comprises a mixture of a first polymer and a second polymer; wherein, The first polymer is a fumarate high-carbon alcohol ester obtained by esterification of high carbon alcohol and fumarate. The second polymer is a methacrylate-norbornene dicarboxylic anhydride polymer obtained by polymerizing methacrylate and norbornene dicarboxylic anhydride.

[0006] Specifically, in the environmentally friendly crude oil pour point depressant, the mass ratio of the first polymer to the second polymer is 1-3:1.

[0007] Specifically, in the environmentally friendly crude oil pour point depressant, the mass ratio of the first polymer to the second polymer is 1-2:1.

[0008] Specifically, in the environmentally friendly crude oil pour point depressant, the first polymer contains a mixture of three fatty alcohols: C20, C22, and C24.

[0009] Specifically, in the environmentally friendly crude oil pour point depressant, the second polymer contains methacrylates, including glycidyl methacrylate.

[0010] The present invention also discloses a method for preparing an environmentally friendly crude oil pour point depressant as described above, comprising the step of mixing the first polymer and the second polymer.

[0011] Specifically, the method for preparing the environmentally friendly crude oil pour point depressant further includes a step of preparing the first polymer, specifically including: esterifying the higher alcohol with fumaric acid in the presence of an esterification catalyst and a polymerization inhibitor.

[0012] Specifically, in the preparation method of the environmentally friendly crude oil pour point depressant, in the preparation step of the first polymer: The molar ratio of the higher alcohol to fumaric acid is 2-3:1; and / or, The catalyst includes p-toluenesulfonic acid; and / or, The amount of catalyst used is 1-2 wt% of the total mass of the higher alcohol and fumaric acid; and / or, The polymerization inhibitor includes hydroquinone; and / or... The amount of the polymerization inhibitor is 0.5-0.8 wt% of the total mass of the higher alcohol and fumaric acid; and / or, The esterification reaction is carried out at a temperature of 120-140°C; and / or, The esterification reaction takes 4-6 hours.

[0013] Specifically, the method for preparing the environmentally friendly crude oil pour point depressant further includes a step of preparing the second polymer, specifically comprising: a step of polymerizing the methacrylate with norbornene dicarboxylic anhydride in the presence of an initiator.

[0014] Specifically, in the preparation method of the environmentally friendly crude oil pour point depressant, the second polymer preparation step includes: The molar ratio of the methacrylate and norbornene dicarboxylic anhydride is 1-5:1; and / or, The initiator includes benzoyl peroxide; and / or, The amount of the initiator is 0.5-1.5 wt% of the total mass of the methacrylate and norbornene dicarboxylic anhydride; and / or, The polymerization reaction is carried out at a temperature of 100-120°C; and / or, The polymerization reaction takes 3-6 hours.

[0015] This invention also discloses the application of the environmentally friendly crude oil pour point depressant or the environmentally friendly crude oil pour point depressant prepared by the method in the field of crude oil pour point depressant; Specifically, the amount of crude oil pour point depressant added is ≥200ppm, preferably 200-500ppm, based on the amount of crude oil added.

[0016] The crude oil pour point depressant product of this invention is based on a fumaric acid high carbon alcohol ester polymer formed by the esterification reaction of fumaric acid and high carbon alcohol esters. Its performance is optimized by mixing and adding a polymer formed by the free radical polymerization of glycidyl methacrylate and norbornene dicarboxylic anhydride. The two are mixed to form the desired crude oil pour point depressant. By utilizing the synergistic effect of the glycidyl methacrylate-norbornene dicarboxylic anhydride polymer on the fumaric acid high carbon alcohol ester polymer, the pour point, cold filter plugging point and viscosity of crude oil products can be effectively improved, further enhancing their low-temperature transportability and low-temperature application performance. Detailed Implementation

[0017] In the following embodiments of the present invention, in order to address the limitations in the application and effectiveness of crude oil pour point depressants, an environmentally friendly crude oil pour point depressant is provided, wherein the crude oil pour point depressant comprises a mixture of a first polymer and a second polymer; wherein, The first polymer is a fumarate high-carbon alcohol ester obtained by esterification of high carbon alcohol and fumarate. The second polymer is a methacrylate-norbornene dicarboxylic anhydride polymer obtained by polymerizing methacrylate and norbornene dicarboxylic anhydride.

[0018] In some specific embodiments, the mass ratio of the first polymer to the second polymer is 1-3:1.

[0019] In some specific embodiments, the mass ratio of the first polymer to the second polymer is 1-2:1.

[0020] In some specific embodiments, the mass ratio of the first polymer to the second polymer is 2:1.

[0021] In some specific embodiments, the higher alcohol in the first polymer comprises a mixture of three fatty alcohols: C20, C22, and C24. The higher alcohol can be any product known in the art, and the preferred mass ratio of the three fatty alcohols (C20, C22, and C24) is 1-2:1-2:1-2; in some specific embodiments, the preferred mass ratio of the three fatty alcohols (C20, C22, and C24) is 1:1:1, and normal mixing is sufficient for use.

[0022] In some specific embodiments, the methacrylate in the second polymer includes glycidyl methacrylate.

[0023] In the following embodiments, the present invention also discloses a method for preparing the environmentally friendly crude oil pour point depressant as described, which includes the step of mixing the first polymer and the second polymer.

[0024] In some specific embodiments, the method further includes the step of preparing the first polymer, specifically including: esterifying the higher alcohol with fumaric acid in the presence of an esterification catalyst and a polymerization inhibitor.

[0025] In some specific embodiments, the preparation step of the first polymer includes: The molar ratio of the higher alcohol to fumaric acid is 2-3:1; and / or, The catalyst includes p-toluenesulfonic acid; and / or, The amount of catalyst used is 1-2 wt% of the total mass of the higher alcohol and fumaric acid; and / or, The polymerization inhibitor includes hydroquinone; and / or... The amount of the polymerization inhibitor is 0.5-0.8 wt% of the total mass of the higher alcohol and fumaric acid; and / or, The esterification reaction is carried out at a temperature of 120-140°C; and / or, The esterification reaction takes 4-6 hours.

[0026] In some specific embodiments, the method further includes the step of preparing the second polymer, specifically including: a step of polymerizing the methacrylate with norbornene dicarboxylic anhydride in the presence of an initiator.

[0027] In some specific embodiments, the preparation step of the second polymer includes: The molar ratio of the methacrylate and norbornene dicarboxylic anhydride is 1-5:1; and / or, The initiator includes benzoyl peroxide; and / or, The amount of the initiator is 0.5-1.5 wt% of the total mass of the methacrylate and norbornene dicarboxylic anhydride; and / or, The polymerization reaction is carried out at a temperature of 100-120°C; and / or, The polymerization reaction takes 3-6 hours.

[0028] Example 1 The environmentally friendly crude oil pour point depressant described in this embodiment comprises a mixture of a first polymer and a second polymer in a mass ratio of 2:1.

[0029] The preparation method of the first polymer includes: adding a higher alcohol (C20:C22:C24=1:1:1) as a raw material into a three-necked flask equipped with a condenser, a water separator, and a magnetic stirrer; adding toluene as a solvent, p-toluenesulfonic acid catalyst, and hydroquinone polymerization inhibitor, and mixing thoroughly; wherein the amount of the catalyst is 1.5% of the total mass of the higher alcohol and fumaric acid, and the amount of the polymerization inhibitor is 0.6% of the total mass of the higher alcohol and fumaric acid; heating the above raw material... The mixture is dissolved and fumaric acid is added to the mixture, wherein the molar ratio of the higher alcohol to the fumaric acid is 2:1. The reaction system is heated to 140°C and reacted for 5 hours. After the reaction is completed, the product is subjected to vacuum distillation to remove toluene, and then the crude ester is washed with 5% NaOH solution at 60°C to remove excess p-toluenesulfonic acid and fumaric acid until the liquid is weakly alkaline. It is then washed with hot distilled water at 80°C until neutral, and then vacuum dried at 60°C for 5 hours to prepare the higher alcohol ester of fumaric acid.

[0030] The preparation method of the second polymer includes: adding glycidyl methacrylate and norbornyl dicarboxylic anhydride to a reaction vessel in a molar ratio of 3:1, and adding sufficient toluene solvent to mix; heating the reaction system to dissolve all the reactants, while simultaneously evacuating the reaction vessel and introducing nitrogen gas to remove air from the reaction system to form a protective atmosphere; continuing to heat to 120°C, and slowly adding an appropriate amount of toluene solution containing benzoyl peroxide, wherein the amount of benzoyl peroxide is 1 wt% of the total mass of the methacrylate and norbornyl dicarboxylic anhydride; stirring and refluxing under the action of the initiator to carry out a polymerization reaction for 5 hours; collecting the reactants and cooling to room temperature, and continuing to add excess ethanol, removing the upper clear liquid by solid-liquid separation, collecting the lower white precipitate, removing benzoyl peroxide from the system, and drying to obtain the methacrylate-norbornyl dicarboxylic anhydride polymer.

[0031] The first polymer and the second polymer mentioned above are mixed to obtain the desired crude oil pour point depressant.

[0032] Example 2 The environmentally friendly crude oil pour point depressant described in this embodiment comprises a mixture of a first polymer and a second polymer in a mass ratio of 1:1.

[0033] The preparation method of the first polymer includes: taking a higher alcohol (C20:C22:C24=1:2:1) as raw material and adding it to a three-necked flask equipped with a condenser, a water separator, and a magnetic stirrer, and adding toluene as solvent, p-toluenesulfonic acid catalyst and hydroquinone polymerization inhibitor, and mixing thoroughly; wherein, the amount of the catalyst accounts for 1% of the total mass of the higher alcohol and fumaric acid, and the amount of the polymerization inhibitor is 0.5% of the total mass of the higher alcohol and fumaric acid; heating the above raw material to fully dissolve it, and continuing to add fumaric acid raw material to mix, wherein the molar ratio of the higher alcohol to the fumaric acid is 3:1; heating the reaction system to 120°C and reacting thoroughly for 5 hours; after the reaction, the product is subjected to vacuum distillation to remove toluene, and then the crude ester is washed with 5% NaOH solution at 60°C to remove excess p-toluenesulfonic acid and fumaric acid until the liquid is weakly alkaline, and then washed with hot distilled water at 80°C until neutral, and then vacuum dried at 60°C for 5 hours to prepare the higher alcohol fumaric acid ester.

[0034] The preparation method of the second polymer includes: adding glycidyl methacrylate and norbornyl dicarboxylic anhydride to a reaction vessel in a 1:1 molar ratio, and adding sufficient toluene solvent to mix; heating the reaction system to dissolve all reactants, while simultaneously evacuating the reaction vessel and introducing nitrogen gas to remove air from the reaction system to form a protective atmosphere; continuing to heat to 100°C, and slowly adding an appropriate amount of toluene solution containing benzoyl peroxide, wherein the amount of benzoyl peroxide is 0.5 wt% of the total mass of the methacrylate and norbornyl dicarboxylic anhydride; stirring and refluxing under the action of the initiator to carry out a polymerization reaction for 5 hours; collecting the reactants and cooling to room temperature, and continuing to add excess ethanol, removing the supernatant by solid-liquid separation, collecting the lower white precipitate, removing benzoyl peroxide from the system, and drying to obtain the methacrylate-norbornyl dicarboxylic anhydride polymer.

[0035] The first polymer and the second polymer mentioned above are mixed to obtain the desired crude oil pour point depressant.

[0036] Example 3 The environmentally friendly crude oil pour point depressant described in this embodiment comprises a mixture of a first polymer and a second polymer in a mass ratio of 3:1.

[0037] The preparation method of the first polymer includes: taking a higher alcohol (C20:C22:C24=2:1:1) as raw material and adding it to a three-necked flask equipped with a condenser, a water separator, and a magnetic stirrer, and adding toluene as solvent, p-toluenesulfonic acid catalyst and hydroquinone polymerization inhibitor, and mixing thoroughly; wherein, the amount of the catalyst accounts for 2% of the total mass of the higher alcohol and fumaric acid, and the amount of the polymerization inhibitor is 0.8% of the total mass of the higher alcohol and fumaric acid; heating the above raw material to fully dissolve it, and continuing to add fumaric acid raw material to mix, wherein the molar ratio of the higher alcohol to the fumaric acid is 3:1; heating the reaction system to 130°C and reacting thoroughly for 5 hours; after the reaction, the product is subjected to vacuum distillation to remove toluene, and then the crude ester is washed with 5% NaOH solution at 60°C to remove excess p-toluenesulfonic acid and fumaric acid until the liquid is weakly alkaline, and then washed with hot distilled water at 80°C until neutral, and then vacuum dried at 60°C for 5 hours to prepare the higher alcohol fumaric acid ester.

[0038] The preparation method of the second polymer includes: adding glycidyl methacrylate and norbornene dicarboxylic anhydride to a reaction vessel in a molar ratio of 5:1, and adding sufficient toluene solvent to mix; heating the reaction system to dissolve all the reactants, while simultaneously evacuating the reaction vessel and introducing nitrogen gas to remove air from the reaction system to form a protective atmosphere; continuing to heat to 110°C, and slowly adding an appropriate amount of toluene solution containing benzoyl peroxide, wherein the amount of benzoyl peroxide is 1.5 wt% of the total mass of the methacrylate and norbornene dicarboxylic anhydride; stirring and refluxing under the action of the initiator to carry out a polymerization reaction for 5 hours; collecting the reactants and cooling to room temperature, and continuing to add excess ethanol, removing the supernatant by solid-liquid separation, collecting the lower white precipitate, removing benzoyl peroxide from the system, and drying to obtain the methacrylate-norbornene dicarboxylic anhydride polymer.

[0039] The first polymer and the second polymer mentioned above are mixed to obtain the desired crude oil pour point depressant.

[0040] Example 4 The environmentally friendly crude oil pour point depressant described in this embodiment comprises a mixture of a first polymer and a second polymer in a mass ratio of 2:1.

[0041] The preparation method of the first polymer includes: taking a higher alcohol (C20:C22:C24=1:2:1) as raw material and adding it to a three-necked flask equipped with a condenser, a water separator, and a magnetic stirrer, and adding toluene as solvent, p-toluenesulfonic acid catalyst and hydroquinone polymerization inhibitor, and mixing thoroughly; wherein, the amount of the catalyst accounts for 1% of the total mass of the higher alcohol and fumaric acid, and the amount of the polymerization inhibitor is 0.5% of the total mass of the higher alcohol and fumaric acid; heating the above raw material to fully dissolve it, and continuing to add fumaric acid raw material to mix, wherein the molar ratio of the higher alcohol to the fumaric acid is 3:1; heating the reaction system to 120°C and reacting thoroughly for 5 hours; after the reaction, the product is subjected to vacuum distillation to remove toluene, and then the crude ester is washed with 5% NaOH solution at 60°C to remove excess p-toluenesulfonic acid and fumaric acid until the liquid is weakly alkaline, and then washed with hot distilled water at 80°C until neutral, and then vacuum dried at 60°C for 5 hours to prepare the higher alcohol fumaric acid ester.

[0042] The preparation method of the second polymer includes: adding glycidyl methacrylate and norbornyl dicarboxylic anhydride to a reaction vessel in a 1:1 molar ratio, and adding sufficient toluene solvent to mix; heating the reaction system to dissolve all reactants, while simultaneously evacuating the reaction vessel and introducing nitrogen gas to remove air from the reaction system to form a protective atmosphere; continuing to heat to 100°C, and slowly adding an appropriate amount of toluene solution containing benzoyl peroxide, wherein the amount of benzoyl peroxide is 0.5 wt% of the total mass of the methacrylate and norbornyl dicarboxylic anhydride; stirring and refluxing under the action of the initiator to carry out a polymerization reaction for 5 hours; collecting the reactants and cooling to room temperature, and continuing to add excess ethanol, removing the supernatant by solid-liquid separation, collecting the lower white precipitate, removing benzoyl peroxide from the system, and drying to obtain the methacrylate-norbornyl dicarboxylic anhydride polymer.

[0043] The first polymer and the second polymer mentioned above are mixed to obtain the desired crude oil pour point depressant.

[0044] Example 5 The environmentally friendly crude oil pour point depressant described in this embodiment comprises a mixture of a first polymer and a second polymer in a mass ratio of 2:1.

[0045] The preparation method of the first polymer includes: taking a higher alcohol (C20:C22:C24=2:1:1) as raw material and adding it to a three-necked flask equipped with a condenser, a water separator, and a magnetic stirrer, and adding toluene as solvent, p-toluenesulfonic acid catalyst and hydroquinone polymerization inhibitor, and mixing thoroughly; wherein, the amount of the catalyst accounts for 2% of the total mass of the higher alcohol and fumaric acid, and the amount of the polymerization inhibitor is 0.8% of the total mass of the higher alcohol and fumaric acid; heating the above raw material to fully dissolve it, and continuing to add fumaric acid raw material to mix, wherein the molar ratio of the higher alcohol to the fumaric acid is 3:1; heating the reaction system to 130°C and reacting thoroughly for 5 hours; after the reaction, the product is subjected to vacuum distillation to remove toluene, and then the crude ester is washed with 5% NaOH solution at 60°C to remove excess p-toluenesulfonic acid and fumaric acid until the liquid is weakly alkaline, and then washed with hot distilled water at 80°C until neutral, and then vacuum dried at 60°C for 5 hours to prepare the higher alcohol fumaric acid ester.

[0046] The preparation method of the second polymer includes: adding glycidyl methacrylate and norbornene dicarboxylic anhydride to a reaction vessel in a molar ratio of 5:1, and adding sufficient toluene solvent to mix; heating the reaction system to dissolve all the reactants, while simultaneously evacuating the reaction vessel and introducing nitrogen gas to remove air from the reaction system to form a protective atmosphere; continuing to heat to 110°C, and slowly adding an appropriate amount of toluene solution containing benzoyl peroxide, wherein the amount of benzoyl peroxide is 1.5 wt% of the total mass of the methacrylate and norbornene dicarboxylic anhydride; stirring and refluxing under the action of the initiator to carry out a polymerization reaction for 5 hours; collecting the reactants and cooling to room temperature, and continuing to add excess ethanol, removing the supernatant by solid-liquid separation, collecting the lower white precipitate, removing benzoyl peroxide from the system, and drying to obtain the methacrylate-norbornene dicarboxylic anhydride polymer.

[0047] The first polymer and the second polymer mentioned above are mixed to obtain the desired crude oil pour point depressant.

[0048] Comparative Example 1 The composition and preparation method of the crude oil pour point depressant described in this comparative example are the same as those in Example 1, except that the crude oil pour point depressant only includes the first polymer.

[0049] Comparative Example 2 The composition and preparation method of the crude oil pour point depressant described in this comparative example are the same as those in Example 1, except that the crude oil pour point depressant only includes the second polymer.

[0050] Comparative Example 3 The composition and preparation method of the crude oil pour point depressant described in this comparative example are the same as those in Example 1, except that the methacrylate in the second polymer is selected as octadecyl methacrylate.

[0051] Comparative Example 4 The composition and preparation method of the crude oil pour point depressant described in this comparative example are the same as those in Example 1, except that in the second polymer, the methacrylate is selected as isobornyl methacrylate.

[0052] Experimental Example This experimental example uses crude oil samples from Panjin Oilfield for testing to verify the effectiveness of the crude oil pour point depressant.

[0053] The crude oil pour point depressants prepared in Example 1 and Comparative Examples 1-4 were mixed with selected crude oil samples at a ratio of 200-500 ppm to obtain test samples. The changes in pour point and viscosity (20℃) were tested respectively, and the results are shown in Table 1 below.

[0054] In this experimental example, the pour point of crude oil was determined using the method SY / T 0541-2009, and the viscosity of crude oil was determined using the rotational viscometer equilibrium method SY / T 0520-2008. The results are shown in Table 1 below. ΔSP represents the range of reduction in the pour point of crude oil after adding the crude oil pour point depressant of this invention relative to the initial crude oil sample; the viscosity reduction rate represents the percentage reduction in viscosity relative to the initial crude oil sample.

[0055] Table 1

[0056] As can be seen, the crude oil pour point depressant product of this invention is based on the traditional fumarate higher alcohol ester, which has a certain pour point depressing effect, and its performance is optimized by adding a methacrylate-norbornene dicarboxylic anhydride polymer. As shown in Table 1, although the methacrylate-norbornene dicarboxylic anhydride polymer selected in this invention does not have a significant effect on reducing pour point and viscosity when used alone, it can assist the pour point depressing effect of fumarate higher alcohol ester. Based on the synergistic effect of the two, it not only effectively improves the pour point and viscosity of crude oil products and further enhances their low-temperature application performance, but also requires a lower dosage and has better environmental performance.

[0057] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. An environmentally friendly crude oil pour point depressant, characterized in that, The crude oil pour point depressant comprises a mixture of a first polymer and a second polymer; wherein, The first polymer is a fumarate high-carbon alcohol ester obtained by esterification of high carbon alcohol and fumarate. The second polymer is a methacrylate-norbornene dicarboxylic anhydride polymer obtained by polymerizing methacrylate and norbornene dicarboxylic anhydride.

2. The environmentally friendly crude oil pour point depressant according to claim 1, characterized in that, The mass ratio of the first polymer to the second polymer is 1-3:

1.

3. The environmentally friendly crude oil pour point depressant according to claim 1 or 2, characterized in that, In the first polymer, the higher alcohols include a mixture of three fatty alcohols: C20, C22, and C24.

4. The environmentally friendly crude oil pour point depressant according to claim 1 or 2, characterized in that, In the second polymer, the methacrylate includes glycidyl methacrylate.

5. A method for preparing an environmentally friendly crude oil pour point depressant as described in any one of claims 1-4, characterized in that, This includes the step of mixing the first polymer and the second polymer.

6. The preparation method of the environmentally friendly crude oil pour point depressant according to claim 5, characterized in that, The method further includes a step of preparing the first polymer, specifically including: an esterification reaction of the higher alcohol with fumaric acid in the presence of an esterification catalyst and a polymerization inhibitor.

7. The preparation method of the environmentally friendly crude oil pour point depressant according to claim 6, characterized in that, In the preparation steps of the first polymer: The molar ratio of the higher alcohol to fumaric acid is 2-3:1; and / or, The catalyst includes p-toluenesulfonic acid; and / or, The amount of catalyst used is 1-2 wt% of the total mass of the higher alcohol and fumaric acid; and / or, The polymerization inhibitor includes hydroquinone; and / or... The amount of the polymerization inhibitor is 0.5-0.8 wt% of the total mass of the higher alcohol and fumaric acid; and / or, The esterification reaction is carried out at a temperature of 120-140°C; and / or, The esterification reaction takes 4-6 hours.

8. The preparation method of the environmentally friendly crude oil pour point depressant according to claim 5, characterized in that, The method further includes a step of preparing the second polymer, specifically including a step of polymerizing the methacrylate with norbornene dicarboxylic anhydride in the presence of an initiator.

9. The preparation method of the environmentally friendly crude oil pour point depressant according to claim 8, characterized in that, In the preparation step of the second polymer: The molar ratio of the methacrylate to norbornene dicarboxylic anhydride is 1-5:1; and / or, The initiator includes benzoyl peroxide; and / or, The amount of the initiator is 0.5-1.5 wt% of the total mass of the methacrylate and norbornene dicarboxylic anhydride; and / or, The polymerization reaction is carried out at a temperature of 100-120°C; and / or, The polymerization reaction takes 3-6 hours.

10. The application of the environmentally friendly crude oil pour point depressant according to any one of claims 1-4 or the environmentally friendly crude oil pour point depressant prepared by the method according to any one of claims 5-9 in the field of crude oil pour point depressant.

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