High-wax-content crude oil pour point depressant and preparation method thereof

Abstract

The invention provides a high wax content crude oil pour point depressant and a preparation method thereof, and belongs to the technical field of pour point depressants.The pour point depressant is prepared by extracting high alcohol from animal and plant waxiness and mixing the prepared higher fatty alcohol with hexadecanol, octadecanol and other short-chain alcohols according to a certain proportion. The distribution of high-carbon alcohol extracted from natural animal and plant wax is close to the waxiness of high-wax-content crude oil, the high-carbon alcohol is used for synthesis and preparation of the pour point depressant, and the obtained pour point depressant product has a good pour point depression effect on the high-wax-content crude oil.

Description

Technical Field

[0001] The present invention belongs to the technical field of pour point depressants, and particularly relates to a pour point depressant for high-wax and high pour point crude oil and a preparation method thereof. Background Art

[0002] At present, the crude oil produced from several major oil fields (Sudan, Chad, Niger) developed by China National Petroleum Corporation in Central Africa belongs to typical high-wax and high pour point crude oil. When the temperature of the crude oil approaches the wax precipitation point, wax crystals will gradually precipitate. As the number of wax crystals increases, a three-dimensional network structure will be formed, resulting in poor fluidity of the crude oil and affecting the normal exploitation and transportation of the crude oil.

[0003] Adding a pour point depressant to crude oil is an effective way to improve the exploitation and transportation processes of high pour point crude oil, which has the advantages of simple operation, less equipment investment, no need for post-treatment, and convenient automatic management of the oil transportation process. At the same time, the chemical agent pour point depression method is also an effective way to achieve the normal temperature transportation of high-wax crude oil and improve the restart of the crude oil after shutdown. The principle of the pour point depressant to reduce the freezing point of crude oil is to change the crystallization behavior of wax in the crude oil through forms such as crystal nucleus, eutectic, and adsorption, effectively inhibit the formation of wax crystals and reduce the structural strength of the crystalline wax, and inhibit the formation of wax deposition, thereby reducing the freezing point of the crude oil.

[0004] However, for high-wax crude oil, its wax content is generally greater than 15%, and the saturated hydrocarbon carbon chain is relatively long, with an average chain length of 25 - 30, and the content of saturated hydrocarbons with a chain length greater than 30 is relatively high, resulting in poor sensitivity of the crude oil to conventional pour point depressants. For high pour point heavy oil with a very high wax content, it is difficult to achieve good results by applying mixed ester copolymers with carbon numbers distributed in C18 and C22. Moreover, the high-carbon alcohols such as tetracosanol, hexacosanol, octacosanol, and triacontanol sold on the market are expensive, resulting in a significant increase in the cost of the final pour point depressant and making it difficult to promote and apply. Summary of the Invention

[0005] Considering both the pour point depressant effect and cost, the present invention creatively starts from low-cost natural animal and plant waxes to prepare mixed high-carbon alcohols for the synthesis of pour point depressants. The extracted high-carbon alcohols have an average chain length of 26 - 30, and the carbon number distribution is close to the wax quality of high-wax crude oil. Then, they are mixed with short-chain alcohols such as hexadecanol and octadecanol for the synthesis and preparation of pour point depressants. The obtained pour point depressant product has a good pour point depression effect on high-wax crude oil.

[0006] One of the purposes of the present invention is to provide a preparation method for a pour point depressant for high-wax crude oil.

[0007] Another purpose of the present invention is to provide a pour point depressant prepared by the preparation method.

[0008] In order to achieve the above purposes of the present invention, the following technical solutions are specifically adopted:

[0009] In a first aspect, the present invention provides a method for preparing a pour point depressant for high-wax crude oil, comprising the following steps:

[0010] (1) Preparation of higher alcohols: Mix calcium oxide or calcium hydroxide with water, then react with natural animal and plant wax by heating, filter to obtain a solid product; then add a solvent to the solid product for extraction, filter while it is hot, and collect the filtrate to precipitate crystals to obtain higher alcohols; wherein the natural animal and plant wax is one or more selected from rice bran wax, sugarcane wax, insect white wax, beeswax, palm wax, and soybean wax;

[0011] (2) Preparation of pour point depressant: First, the mixed fatty alcohols are subjected to an esterification reaction with acrylic acid or methacrylic acid, and then polymerized with small molecule monomers to obtain a pour point depressant;

[0012] Or the small molecule monomers are copolymerized first, and then subjected to alcoholysis with the mixed fatty alcohols to obtain a pour point depressant;

[0013] Wherein the mixed fatty alcohols include the higher alcohols and C16-C18 short-chain alcohols, and the small molecule monomers are one or more selected from maleic anhydride, acrylamide, acrylic acid, styrene, cyclopentadiene, and vinyl acetate (vinyl acetate).

[0014] The following is a detailed description of each step:

[0015] The wax content (wax content) of the high-wax crude oil is greater than 15%, preferably, the wax of the high-wax crude oil is composed of long-chain alkanes of C21-C32, the average chain length of the carbon chain is 25-30, specifically, it includes the following components by weight percentage: n-heneicosane 0-1.0%, n-docosane 0.5-5%, n-tricosane 0.5-10%, n-tetracosane 1-15%, n-pentacosane 1-15%, n-hexacosane 5-18%, n-heptacosane 5-20%, n-octacosane 6-20%, n-nonacosane 5-15%, n-triacontane 2-14%, n-hentriacontane 1-10%, n-dotriacontane 0-8%, especially: n-heneicosane 0.6%, n-docosane 3.7%, n-tricosane 7.4%, n-tetracosane 10.5%, n-pentacosane 12.8%, n-hexacosane 12.1%, n-heptacosane 13.3%, n-octacosane 10.5%, n-nonacosane 10.1%, n-triacontane 9.6%, n-hentriacontane 5.2%, n-dotriacontane 4.2%.

[0016] Step (1): Preparation of higher alcohols

[0017] Extracting higher alcohols from natural animal and plant wax mainly goes through four steps: heating and melting, saponification reaction, extraction and filtration, and recrystallization.

[0018] In some embodiments, step (1) includes the following steps:

[0019] (1.1) Add calcium oxide or calcium hydroxide and water to a reaction kettle, heat and dissolve; add natural animal and plant waxes for a temperature-raising reaction, filter to obtain a solid product, and wash with water.

[0020] (1.2) Add a solvent to the solid product for extraction, filter while it is hot, collect the filtrate and precipitate crystals to obtain higher alcohols.

[0021] Preferably, in step (1.1), by weight ratio, 100 parts of natural animal and plant waxes, 15 - 20 parts of calcium oxide or calcium hydroxide, and 20 - 40 parts of water are used.

[0022] Preferably, in step (1.1), the heating and dissolving temperature is 80 - 100 °C.

[0023] Preferably, in step (1.1), the temperature-raising reaction temperature is 200 - 250 °C, and the reaction time is 7 - 8 hours.

[0024] Preferably, in step (1.2), the solvent is one or more selected from ethanol, chloroform, isopropanol, n-propanol, butanol, butanone, acetone, pentane, and n-hexane.

[0025] Preferably, in step (1.2), based on every 100 parts of natural animal and plant waxes by weight ratio, the addition amount of the solvent is 800 - 1200 parts.

[0026] Preferably, in step (1.2), the extraction temperature is 70 - 80 °C, and the extraction time is 1 - 3 hours.

[0027] In some embodiments, the average chain length of the carbon chain of the higher alcohols obtained in step (1) is 26 - 30. Specifically, it includes the following components by weight percentage: 0 - 0.5% of 1-docosanol, 0.3 - 7% of 1-tetracosanol, 2 - 40% of 1-hexacosanol, 10 - 60% of 1-octacosanol, 7 - 45% of 1-triacontanol, 1 - 38% of 1-dotriacontanol, 0 - 16% of 1-tetratriacontanol, 0 - 11% of 1-hexatriacontanol, and 0 - 3% of 1-octatriacontanol.

[0028] Step (2): Preparation of pour point depressant

[0029] Prepare a pour point depressant by mixing the prepared higher alcohols with short-chain alcohols such as hexadecanol and octadecanol in a certain proportion. The preparation scheme includes:

[0030] Method 1: First, carry out an esterification reaction of the mixed fatty alcohols with acrylic acid or methacrylic acid, and then polymerize with small molecule monomers to obtain a pour point depressant.

[0031] In some embodiments, step (2) includes the following steps:

[0032] (2.1) Mix the higher alcohol and C16-C18 short-chain alcohol, add acrylic acid or methacrylic acid, and then add an inhibitor and a catalyst for an esterification reaction to obtain a mixed acrylate ester;

[0033] (2.2) Mix and heat the mixed acrylate ester and small molecule monomers, add a solvent and an initiator for a polymerization reaction to obtain a pour point depressant.

[0034] In step (2.1), the weight ratio is 5-30 parts of higher alcohol, 70-95 parts of C16-C18 short-chain alcohol, 0.1-0.6 parts of inhibitor, and 0.5-5 parts of catalyst; the addition amount of acrylic acid or methacrylic acid is 0-15% in excess of the total molar amount of the alcohol;

[0035] Preferably, in step (2.1), the inhibitor is one or more selected from hydroquinone, p-methoxyphenol, benzaldehyde, 2,6-di-tert-butyl-4-methylphenol, and p-toluenesulfonamide; the catalyst is one or more selected from p-toluenesulfonic acid, sulfuric acid, phosphoric acid, formic acid, and acetic acid;

[0036] Preferably, in step (2.1), the esterification reaction temperature is 120-150 °C and the reaction time is 4-8 hours;

[0037] Preferably, in step (2.2), the small molecule monomers are maleic anhydride and styrene, or maleic anhydride and acrylamide; the weight ratio is 20-60 parts of mixed acrylate ester, 4-15 parts of maleic anhydride, 1-10 parts of styrene or acrylamide, 30-70 parts of solvent, and 0.5-5 parts of initiator;

[0038] Preferably, in step (2.2), the initiator is one or more selected from azobisisobutyronitrile, benzoyl peroxide, di-tert-butyl peroxide, tert-butyl perbenzoate, dicumyl peroxide, and cumene hydroperoxide;

[0039] Preferably, the solvent in step (2.2) is selected from one or more of toluene, xylene, trimethylbenzene, tetramethylbenzene, high-boiling solvent oil, diesel oil, and kerosene;

[0040] Preferably, in step (2.2), the polymerization reaction temperature is 80-180 °C and the reaction time is 4-6 hours.

[0041] Method 2: The small molecule monomers are first copolymerized and then alcoholyzed with the mixed fatty alcohol to obtain a pour point depressant.

[0042] In some embodiments, step (2) includes the following steps:

[0043] Mix maleic anhydride, solvent, styrene, and initiator for a copolymerization reaction, and then add higher alcohol, C16-C18 short-chain alcohol, and catalyst for an alcoholysis reaction to obtain a pour point depressant.

[0044] Preferably, by weight parts, 5 - 15 parts of maleic anhydride, 100 parts of solvent, 1 - 12 parts of styrene, 0.1 - 1 part of initiator, 5 - 20 parts of higher alcohol, 20 - 60 parts of C16 - C18 short-chain alcohol, and 1 - 10 parts of catalyst;

[0045] Preferably, the copolymerization reaction temperature is 80 - 180 °C, and the reaction time is 3 - 6 hours;

[0046] Preferably, the alcoholysis reaction temperature is 130 - 180 °C, and the reaction time is 2 - 6 hours;

[0047] Preferably, the solvent is one or more selected from toluene, xylene, trimethylbenzene, tetramethylbenzene, high-boiling solvent oil, diesel, and kerosene;

[0048] Preferably, the initiator is one or more selected from azobisisobutyronitrile, benzoyl peroxide, di-tert-butyl peroxide, tert-butyl perbenzoate, dicumyl peroxide, and cumene hydroperoxide;

[0049] Preferably, the catalyst is one or more selected from p-toluenesulfonic acid, sulfuric acid, phosphoric acid, formic acid, and acetic acid.

[0050] In a second aspect, the present invention provides a pour point depressant prepared by the preparation method of the above high-wax crude oil pour point depressant.

[0051] The pour point depressant obtained by the present invention has a good pour point depression effect in high-wax and high pour point crude oil.

[0052] Beneficial Effects

[0053] Starting from the pour point depression principle, the number of carbon atoms in the long alkyl main chain or long alkyl side chain of the pour point depressant should match the average number of carbon atoms in the most concentrated range of the carbon number distribution of wax in the crude oil to have a good pour point depression effect. By introducing higher carbon chains and extracting higher alcohols from natural animal and plant waxes, higher alcohols with a wax distribution similar to that of high-wax crude oil wax are obtained, and the pour point depressant prepared therefrom has a good pour point depression effect.

[0054] The present invention has been described in detail above, but the above embodiments are essentially illustrative only and are not intended to limit the present invention. In addition, the present invention is not limited by any theory described in the foregoing prior art or the invention content or the following examples. Description of the Drawings

[0055] Figure 1 It is the gas chromatogram of wax in the crude oil of a certain oilfield block in Africa. Detailed Embodiments

[0056] The present invention will be further described below in conjunction with embodiments. It should be noted that the following embodiments are provided for illustrative purposes only and do not constitute a limitation on the scope of protection required by the present invention.

[0057] Unless otherwise specified, the raw materials, reagents, methods, etc. used in the embodiments are all conventional raw materials, reagents, and methods in the art.

[0058] The raw materials involved in the embodiments are as follows:

[0059] Rice bran wax was purchased from Cangzhou Forest Wax Industry Co., Ltd.;

[0060] Sugarcane wax was purchased from Wuhan Lvjing Fenghua Biotechnology Co., Ltd.;

[0061] Chinese insect wax was purchased from Cangzhou Forest Wax Industry Co., Ltd.;

[0062] Beeswax was purchased from Hebei Xushi Beeswax Co., Ltd.

[0063] In the embodiments, high-wax crude oil from a certain oilfield block in Africa of PetroChina was used as the experimental oil. The wax content of this experimental oil (determination of wax content in crude oil by GB / T 26982-2022) was 15%, and the pour point (determination method of pour point of crude oil by SYT 0541-2009) was 32 °C.

[0064] The wax structure in this experimental oil was tested by gas chromatography ( Figure 1 ), and the relative content of long-chain alkanes in the wax was analyzed (Table 1). It was found that the wax was composed of long-chain alkanes with C21-C32, the main components were long-chain alkanes with C24-C30, the contents of each long-chain alkane showed a normal distribution, and the average carbon chain length was close to 27.

[0065] Table 1 Wax component content wt% of crude oil from a certain oilfield block in Africa

[0066] Structure C21 C22 C23 C24 C25 C26 C27 C28 C29 C30 C31 C32 Content 0.6 3.7 7.4 10.5 12.8 12.1 13.3 10.5 10.1 9.6 5.2 4.2

[0067] Preparation Example 1 Preparation of higher alcohols

[0068] Take 15 parts of calcium oxide and 25 parts of water and add them to the reaction kettle, heat to 90 °C to dissolve; take 100 parts of rice bran wax and add it to the reaction kettle. Raise the temperature to 200 °C and react for 7 hours. Filter out the liquid, cool to 95 °C and wash 3 times with water. Then add about 1200 parts of ethanol, extract at 75 °C for 2 hours, filter while it is hot, and collect the filtrate to precipitate crystals to obtain higher alcohols.

[0069] Preparation Example 2 Preparation of higher alcohols

[0070] Take 15 parts of calcium hydroxide and 30 parts of water and add them to the reaction kettle, heat to 90 °C for dissolution; take 100 parts of Chinese insect wax and add it to the reaction kettle. Raise the temperature to 200 °C and react for 7 hours. Filter out the liquid, cool down to 95 °C and wash with water 3 times. Then add about 1000 parts of chloroform, extract at 75 °C for 2 hours, filter while it is hot, collect the filtrate and precipitate crystals to obtain higher alcohols.

[0071] Preparation Example 3 Preparation of Higher Alcohols

[0072] Take 20 parts of calcium hydroxide and 30 parts of water and add them to the reaction kettle, heat to 100 °C for dissolution; take 100 parts of sugarcane wax and add it to the reaction kettle. Raise the temperature to 220 °C and react for 7 hours. Filter out the liquid, cool down to 90 °C and wash with water 3 times. Then add about 1000 parts of a mixed solvent of isopropanol and n-hexane, extract at 75 °C for 2 hours, filter while it is hot, collect the filtrate and precipitate crystals to obtain higher alcohols.

[0073] Preparation Example 4 Preparation of Higher Alcohols

[0074] Take 15 parts of calcium oxide and 20 parts of water and add them to the reaction kettle, heat to 100 °C for dissolution; take 100 parts of beeswax and add it to the reaction kettle. Raise the temperature to 250 °C and react for 8 hours. Filter out the liquid, cool down to 95 °C and wash with water 3 times. Then add about 1000 parts of a mixed solvent of methyl ethyl ketone and n-propanol, extract at 80 °C for 2 hours, filter while it is hot, collect the filtrate and precipitate crystals to obtain higher alcohols.

[0075] Analyze the relative contents of different higher alcohols in the higher alcohols obtained by extracting with rice bran wax, Chinese insect wax, sugarcane wax, and beeswax in Preparation Examples 1-4 (Table 2). The average chain length of the higher alcohols extracted from animal and plant waxes is 26-30, and the carbon number distribution is close to that of the wax in high-wax crude oil. Among them, the average chain lengths of rice bran wax and beeswax are close to 30, and the average chain lengths of Chinese insect wax and sugarcane wax are close to 28. The contents of each higher alcohol are all normally distributed, and the trend is close to the distribution of wax in crude oil.

[0076] Table 2 Relative Contents of Higher Alcohols in Different Animal and Plant Waxes

[0077]

[0078]

[0079] Example 1 Preparation of Pour Point Depressant for High-Wax Crude Oil

[0080] (1) Synthesis of acrylate: Take 15 parts of the higher alcohol from Preparation Example 1, 85 parts of octadecanol, add 30 parts of acrylic acid, 0.3 part of hydroquinone, and 1 part of p-toluenesulfonic acid into the reaction kettle. Raise the temperature to 130 °C and react for 4 hours, cool down to 90 °C and wash with water three times. Filter out the liquid and collect the solid to obtain the acrylic acid mixed ester.

[0081] (2) Pour point depressant synthesis: Take 50 parts of the prepared acrylic acid mixed ester, add 4 parts of maleic anhydride, 2 parts of styrene, and 60 parts of xylene into the reaction kettle, heat to 60 °C and stir to mix evenly. Add 0.5 part of azobisisobutyronitrile, raise the temperature to 95 °C and react for 5 hours to obtain the finished pour point depressant.

[0082] According to the standard of "SYT 0541-2009 Crude Oil Pour Point Determination Method", the pour point of the crude oil pour point depressant is detected. Under the condition that the addition amount of the pour point depressant is 4000 ppm, the pour point of the crude oil can be reduced to 22 °C.

[0083] Example 2 Preparation of Pour Point Depressant for High-Wax Crude Oil

[0084] Put 9.8 parts of maleic anhydride and 100 parts of mesitylene into the reaction kettle, pass nitrogen for 5 minutes, turn on the heating and stirring, raise the temperature to 80 °C, add 10.4 parts of styrene, dropwise add 0.25 part of benzoyl peroxide, and raise the temperature to 90 °C and keep it warm for 3 hours.

[0085] Add 26 parts of octadecanol, 5.2 parts of the higher alcohol prepared in Preparation Example 2, and 2 parts of p-toluenesulfonic acid. Raise the temperature to 150 °C, reflux and react for 4 hours, and then cool to room temperature to obtain the finished pour point depressant.

[0086] According to the standard of "SYT 0541-2009 Crude Oil Pour Point Determination Method", the pour point of the crude oil pour point depressant is detected. Under the condition that the addition amount of the pour point depressant is 4000 ppm, the pour point of the crude oil can be reduced to 21 °C.

[0087] Example 3

[0088] Put 7.4 parts of maleic anhydride and 100 parts of mesitylene into the reaction kettle, pass nitrogen for 5 minutes, turn on the heating and stirring, raise the temperature to 80 °C, add 5.2 parts of styrene, dropwise add 0.5 part of benzoyl peroxide, and raise the temperature to 85 °C and keep it warm for 4 hours.

[0089] Add 38 parts of octadecanol, 7.8 parts of the higher alcohol prepared in Preparation Example 3, and 2 parts of p-toluenesulfonic acid. Raise the temperature to 150 °C, reflux and react for 4 hours, and then cool to room temperature to obtain the finished pour point depressant.

[0090] According to the standard of "SYT 0541-2009 Crude Oil Pour Point Determination Method", the pour point of the crude oil pour point depressant is detected. Under the condition that the addition amount of the pour point depressant is 4000 ppm, the pour point of the crude oil can be reduced to 21.5 °C.

[0091] Example 4

[0092] (1) Acrylate synthesis: Take 20 parts of the higher alcohol prepared in Preparation Example 4 and 80 parts of octadecyl alcohol, add 30 parts of acrylic acid, 0.5 part of hydroquinone, and 2 parts of p-toluenesulfonic acid into the reaction kettle. Raise the temperature to 125 °C and react for 5 hours, then cool to 90 °C and wash three times with water. Filter to remove the liquid and collect the solid to obtain the acrylic acid mixed ester.

[0093] (2) Synthesis of pour point depressant: Take 50 parts of the prepared acrylic acid mixed ester, add 5 parts of maleic anhydride, 2 parts of acrylamide, and 60 parts of mesitylene into the reaction kettle, heat to 60 °C and stir to mix evenly. Add 0.5 part of azobisisobutyronitrile, raise the temperature to 85 °C and react for 6 hours to obtain the finished pour point depressant product.

[0094] According to the standard of "SYT 0541-2009 Method for Determination of Pour Point of Crude Oil", the pour point of the crude oil pour point depressant is detected. Under the condition that the addition amount of the pour point depressant is 4000 ppm, the pour point of the crude oil can be reduced to 22.5 °C.

[0095] Comparative Example 1

[0096] (1) Synthesis of acrylic ester: Take 15 parts of docosanol and 85 parts of octadecanol, add 30 parts of acrylic acid, 0.3 part of hydroquinone, and 1 part of p-toluenesulfonic acid into the reaction kettle. Raise the temperature to 130 °C and react for 4 hours, then cool to 90 °C and wash with water three times. Filter to remove the liquid and collect the solid to obtain the acrylic acid mixed ester.

[0097] (2) Synthesis of pour point depressant: Take 50 parts of the prepared acrylic acid mixed ester, add 4 parts of maleic anhydride, 2 parts of styrene, and 60 parts of xylene into the reaction kettle, heat to 60 °C and stir to mix evenly. Add 0.5 part of azobisisobutyronitrile, raise the temperature to 95 °C and react for 5 hours to obtain the finished pour point depressant product.

[0098] According to the standard of "SYT 0541-2009 Method for Determination of Pour Point of Crude Oil", the pour point of the crude oil pour point depressant is detected. Under the condition that the addition amount of the pour point depressant is 4000 ppm, the pour point of the crude oil can be reduced to 25 °C.

[0099] Comparative Example 2

[0100] Put 7.4 parts of maleic anhydride and 100 parts of mesitylene into the reaction kettle, pass nitrogen for 5 minutes, start heating and stirring, raise the temperature to 80 °C, add 5.2 parts of styrene, dropwise add 0.5 part of benzoyl peroxide, and raise the temperature to 85 °C for heat preservation for 4 hours.

[0101] Add 45.8 parts of octadecanol and 2 parts of p-toluenesulfonic acid. Raise the temperature to 150 °C, carry out reflux reaction for 4 hours and then cool to room temperature to obtain the finished pour point depressant product.

[0102] According to the standard of "SYT 0541-2009 Method for Determination of Pour Point of Crude Oil", the pour point of the crude oil pour point depressant is detected. Under the condition that the addition amount of the pour point depressant is 4000 ppm, the pour point of the crude oil can be reduced to 28 °C.

Claims

1. A preparation method of a pour point depressant for high-wax crude oil, characterized in that It includes the following steps: (1) Preparation of higher alcohols: Mix calcium oxide or calcium hydroxide with water, then react with natural animal and plant wax by heating, filter to obtain a solid product; then add a solvent to the solid product for extraction, filter while it is hot, and collect the filtrate to precipitate crystals to obtain higher alcohols; wherein the natural animal and plant wax is one or more selected from rice bran wax, sugarcane wax, insect white wax, beeswax, palm wax, and soybean wax; (2) Preparation of pour point depressant: First, carry out an esterification reaction of mixed fatty alcohols with acrylic acid or methacrylic acid, and then polymerize with small molecule monomers to obtain a pour point depressant; or, First, copolymerize small molecule monomers, and then carry out alcoholysis with mixed fatty alcohols to obtain a pour point depressant; wherein the mixed fatty alcohols include the higher alcohols and C16-C18 short-chain alcohols, and the small molecule monomers are one or more selected from maleic anhydride, styrene, cyclopentadiene, vinyl acetate, acrylic acid, and acrylamide.

2. The preparation method according to claim 1, characterized in that, The wax content of the high-wax crude oil is greater than 15%, preferably, the wax in the high-wax crude oil is composed of long-chain alkanes with C21-C32, the average chain length of the carbon chain is 25-30, specifically, it includes the following components by weight percentage: n-heneicosane 0-1.0%, n-docosane 0.5-5%, n-tricosane 0.5-10%, n-tetracosane 1-15%, n-pentacosane 1-15%, n-hexacosane 5-18%, n-heptacosane 5-20%, n-octacosane 6-20%, n-nonacosane 5-15%, n-triacontane 2-14%, n-hentriacontane 1-10%, n-dotriacontane 0-8%.

3. The preparation method according to claim 1, characterized in that, Step (1) includes the following steps: (1.1) Add calcium oxide or calcium hydroxide and water to a reaction kettle, heat and dissolve; add natural animal and plant wax for heating reaction, filter to obtain a solid product, and wash with water; (1.2) Add a solvent to the solid product for extraction, filter while it is hot, and collect the filtrate to precipitate crystals to obtain higher alcohols.

4. The preparation method according to claim 3, characterized in that, In step (1.1), by weight ratio, 100 parts of natural animal and plant wax, 15-20 parts of calcium oxide or calcium hydroxide, and 20-40 parts of water; Preferably, in step (1.1), the heating and dissolving temperature is 80-100 °C; Preferably, in step (1.1), the heating reaction temperature is 200-250 °C, and the reaction time is 7-8 hours.

5. The preparation method according to claim 3, characterized in that, In step (1.2), the solvent is one or more selected from ethanol, chloroform, isopropanol, n-propanol, butanol, butanone, acetone, pentane, and n-hexane; Preferably, in step (1.2), based on every 100 parts of natural animal and plant wax by weight ratio, the addition amount of the solvent is 800-1200 parts; Preferably, in step (1.2), the extraction temperature is 70-80 °C, and the extraction time is 1-3 hours.

6. The preparation method according to claim 3, characterized in that, The average chain length of the carbon chain of the higher alcohols obtained in step (1) is 26-30, specifically, it includes the following components by weight percentage: 1-docosanol 0-0.5%, 1-tetracosanol 0.3-7%, 1-hexacosanol 2-40%, 1-octacosanol 10-60%, 1-triacontanol 7-45%, 1-dotriacontanol 1-38%, 1-tetratriacontanol 0-16%, 1-hexatriacontanol 0-11%, 1-octatriacontanol 0-3%.

7. The preparation method according to claim 1, characterized in that, Step (2) includes the following steps: (2.1) Mix a higher alcohol and a C16-C18 short-chain alcohol, add acrylic acid or methacrylic acid, and then add an inhibitor and a catalyst for an esterification reaction to obtain a mixed acrylic ester; (2.2) Mix and heat the mixed acrylic ester and a small molecule monomer, add a solvent and an initiator for a polymerization reaction to obtain a pour point depressant.

8. The preparation method according to claim 7, characterized in that, In step (2.1), by weight ratio, there are 5-30 parts of higher alcohol, 70-95 parts of C16-C18 short-chain alcohol, 0.1-0.6 part of inhibitor, and 0.5-5 parts of catalyst; the addition amount of acrylic acid or methacrylic acid is 0-15% in excess of the total molar amount of the alcohol; Preferably, in step (2.1), the inhibitor is one or more selected from hydroquinone, p-methoxyphenol, benzaldehyde, 2,6-di-tert-butyl-4-methylphenol, and p-toluenesulfonamide; the catalyst is one or more selected from p-toluenesulfonic acid, sulfuric acid, phosphoric acid, formic acid, and acetic acid; Preferably, in step (2.1), the esterification reaction temperature is 120-150 °C and the reaction time is 4-8 hours; Preferably, in step (2.2), the small molecule monomer is maleic anhydride and styrene, or maleic anhydride and acrylamide. By weight ratio, there are 20-60 parts of mixed acrylic ester, 4-15 parts of maleic anhydride, 1-10 parts of styrene or acrylamide, 30-70 parts of solvent, and 0.5-5 parts of initiator; Preferably, in step (2.2), the initiator is one or more selected from azobisisobutyronitrile, benzoyl peroxide, di-tert-butyl peroxide, tert-butyl peroxybenzoate, diisopropylbenzene peroxide, and cumene hydroperoxide; Preferably, the solvent in step (2.2) is selected from one or more of toluene, xylene, trimethylbenzene, tetramethylbenzene, high-boiling solvent oil, diesel, and kerosene; Preferably, in step (2.2), the polymerization reaction temperature is 80-180 °C and the reaction time is 4-6 hours.

9. The preparation method according to claim 1, characterized in that, Step (2) includes the following steps: Mix maleic anhydride, a solvent, styrene, and an initiator for a copolymerization reaction, and then add a higher alcohol, a C16-C18 short-chain alcohol, and a catalyst for an alcoholysis reaction to obtain a pour point depressant; Preferably, by weight ratio, there are 5-15 parts of maleic anhydride, 100 parts of solvent, 1-12 parts of styrene, 0.1-1 part of initiator, 5-20 parts of higher alcohol, 20-60 parts of C16-C18 short-chain alcohol, and 1-10 parts of catalyst; Preferably, the copolymerization reaction temperature is 80-180 °C and the reaction time is 3-6 hours; Preferably, the alcoholysis reaction temperature is 130-180 °C and the reaction time is 2-6 hours; Preferably, the initiator is one or more selected from azobisisobutyronitrile, benzoyl peroxide, di-tert-butyl peroxide, tert-butyl peroxybenzoate, diisopropylbenzene peroxide, and cumene hydroperoxide; Preferably, the solvent is selected from one or more of toluene, xylene, trimethylbenzene, tetramethylbenzene, high-boiling solvent oil, diesel, and kerosene; Preferably, the catalyst is one or more selected from p-toluenesulfonic acid, sulfuric acid, phosphoric acid, formic acid, and acetic acid.

10. A pour point depressant, characterized in that, Prepared by the preparation method of the high-wax crude oil pour point depressant according to any one of claims 1-9.

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