Polyhydroxy demulsifier as well as preparation method and application thereof

Abstract

The invention discloses a polyhydroxy demulsifier as well as a preparation method and application thereof, and belongs to the technical field of oil-water emulsion treatment. The polyhydroxy demulsifier has one or more of compounds shown in the following structural formula: # imgabs0, and the invention also provides a preparation method of the polyhydroxy demulsifier, and the preparation method comprises the following steps: taking diethyl bis (hydroxymethyl) malonate and polyethylene polyamine as raw materials, and carrying out amidation reaction in the presence of a solvent A to obtain an amidation product; and mixing the amidation product obtained in the step S1 with alkylamine for reaction to obtain the polyhydroxy demulsifier. In addition, the invention also provides an application of the polyhydroxy demulsifier or the polyhydroxy demulsifier prepared by the preparation method in demulsification of crude oil emulsion. The polyhydroxy demulsifier provided by the invention is high in surface activity, good in thermal stability, good in dispersity in an oil phase, suitable for a petroleum crude oil emulsion and high in demulsification efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of oil-water emulsion treatment, and particularly to a polyhydroxy demulsifier and its preparation method and application. Background Art

[0002] During the oil extraction process, due to various factors, formation water will emulsify with crude oil, especially those crude oils with high asphaltene content. During the production and transportation of crude oil, water-in-oil (W / O) emulsions are usually formed. Most of the crude oil in the world is in an emulsified state, which is not desirable. In addition, the high salt concentration in any residual water in the recovered oil will cause corrosion of downstream process equipment and catalyst poisoning, affecting the efficiency of the refining process and product quality. Therefore, water must be separated from oil before transportation and refining.

[0003] The demulsification of crude oil emulsions mainly uses physical, chemical, biological, and composite treatment methods. In the actual production process of oilfields, chemical demulsification is widely used because of its simplicity and high efficiency, and it is the most commonly used demulsification technology at present. However, in some cases, these demulsifiers are toxic and will cause environmental problems. And traditional demulsifiers also have problems such as large dosage and high demulsification temperature. Moreover, most chemical demulsifiers need to be prepared through a complex synthesis process, and the required raw material costs are relatively high. Developing green, environmentally friendly, and economically efficient demulsifiers is challenging. Therefore, the research and development of crude oil emulsion demulsifiers can mainly be carried out from aspects such as reducing costs, simplifying the synthesis process, and reducing the types of raw materials, in order to develop highly efficient and pollution-free demulsifiers.

[0004] A chemical demulsifier is a surfactant molecule that can break the film formed by surface active substances such as asphaltenes and cause water droplets to coagulate when used in emulsions. In addition, the chemical demulsifier will migrate to the oil-water interface. When using a demulsifier to demulsify crude oil emulsions, the selection of chemical reagents, the dosage of chemical reagents, the dosage of demulsifier, and the length of the demulsification time in the separation instrument are all important factors that need to be considered.

[0005] How to achieve efficient demulsification of crude oil emulsions is a technical problem that needs to be solved by the existing technology. Summary of the Invention

[0006] The purpose of the present invention is to overcome the above technical deficiencies, provide a polyhydroxy demulsifier and its preparation method and application, and solve the technical problem of how to achieve efficient demulsification of crude oil emulsions in the existing technology.

[0007] To achieve the above technical purpose, the technical solution of the present invention provides a polyhydroxy demulsifier, which is one or more of the following structural formula compounds:

[0008]

[0009] Wherein, x is any integer from 3 to 5, and R is C 12 -C 18 any alkyl group in

[0010] In any embodiment, it has one or more of the following structural formula compounds:

[0011]

[0012] In addition, the present invention also provides a preparation method of the above polyhydroxy demulsifier, comprising the following steps:

[0013] S1. Using diethyl dihydroxymethylmalonate and polyethylenepolyamine as raw materials, and carrying out an amidation reaction in the presence of solvent A to obtain an amidation product;

[0014] S2. Mixing and reacting the amidation product obtained in step S1 with an alkylamine to obtain the polyhydroxy demulsifier.

[0015] In any embodiment, in step S1, the molar ratio of diethyl dihydroxymethylmalonate to polyethylenepolyamine is 1:(2 - 3).

[0016] In any embodiment, in step S2, the molar ratio of diethyl dihydroxymethylmalonate to the alkylamine is 1:(1 - 1.5).

[0017] In any embodiment, in step S1, the polyethylenepolyamine is one or more of triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine; and / or, the solvent A is one or both of methanol and ethanol; and / or, in step S2, the alkylamine is one or more of dodecylamine, hexadecylamine and octadecylamine.

[0018] In any embodiment, in step S1, the time of the amidation reaction is 20 - 24 h.

[0019] In addition, the present invention also provides an application of the above polyhydroxy demulsifier or the polyhydroxy demulsifier prepared by the above preparation method in demulsifying crude oil emulsion.

[0020] In any embodiment, the above application includes: dissolving the polyhydroxy demulsifier in solvent B to obtain a demulsifier solution, and then mixing and demulsifying with the crude oil emulsion.

[0021] In any embodiment, the solvent B is one or more of water, ethanol, and xylene; and / or, the mass fraction of the polyhydroxy demulsifier in the demulsifier solution is 0.2 wt% to 0.6 wt%; and / or, the volume ratio of the demulsifier solution to the crude oil emulsion is 1:(10 - 20); and / or, the temperature for demulsification is 40 to 70 °C, and the time is 2 to 3 h.

[0022] Compared with the prior art, the beneficial effects of the present invention include: the polyhydroxy demulsifier proposed by the present invention has high surface activity, good thermal stability, good dispersibility in the oil phase, is applicable to petroleum crude oil emulsions, has high demulsification efficiency, low demulsification temperature, and fast demulsification rate.

[0023] In addition, the method for preparing the demulsifier proposed by the present invention has simple steps and low raw material costs. Description of the Drawings

[0024] Figure 1 Infrared spectrum of the demulsifier prepared in Example 1.

[0025] Figure 2 Infrared spectrum of the demulsifier prepared in Example 2.

[0026] Figure 3 Infrared spectrum of the demulsifier prepared in Example 3.

[0027] Figure 4 Infrared spectrum of the demulsifier prepared in Example 4. Detailed Embodiments

[0028] The "ranges" disclosed in this application are defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundaries of a particular range. The ranges defined in this way can include or exclude the end values and can be combined arbitrarily, that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, ranges of 60-110 and 80-120 are also contemplated. In addition, if the minimum range values of 1 and 2 are listed, and if the maximum range values of 3, 4, and 5 are listed, the following ranges are all contemplated: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "a-b" represents an abbreviated representation of any real number combination between a and b, where both a and b are real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are fully listed herein, and "0-5" is only an abbreviated representation of these numerical combinations. Additionally, when stating that a certain parameter is an integer ≥2, it is equivalent to disclosing that the parameter is, for example, the integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0029] If there is no special indication, the "including" and "comprising" mentioned in this application mean open-ended and can also be closed-ended. For example, the said "including" and "comprising" can mean that other components not listed can also be included or comprised, or it can only include or comprise the listed components.

[0030] If there is no special indication, in this application, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, any of the following conditions satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist); A is false (or does not exist) while B is true (or exists); or both A and B are true (or exist).

[0031] This specific embodiment provides a polyhydroxy demulsifier having one or more of the following structural formula compounds:

[0032]

[0033] Wherein, x is any integer from 3 to 5, and R is any alkyl group in C 12 -C 18 Any of the alkyl groups.

[0034] In some embodiments, the polyhydroxy demulsifier is one or more of the following structural formula compounds:

[0035]

[0036] In addition, this specific embodiment also provides a method for preparing the above polyhydroxy demulsifier, which includes the following steps:

[0037] S1. Using diethyl bis(hydroxymethyl)malonate and polyalkylene polyamine as raw materials, under the condition of the presence of solvent A, carry out amidation reaction for 20 - 24 h to obtain an amidation product; the molar ratio of diethyl bis(hydroxymethyl)malonate to polyalkylene polyamine is 1:(2 - 3); the polyalkylene polyamine is one or more of triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine; the solvent A is one or both of methanol and ethanol;

[0038] S2. Mix and react the amidation product obtained in step S1 with alkylamine to obtain the polyhydroxy demulsifier; the molar ratio of diethyl bis(hydroxymethyl)malonate to alkylamine is 1:(1 - 1.5); the alkylamine is one or more of dodecylamine, hexadecylamine, and octadecylamine.

[0039] In addition, this specific embodiment also provides an application of the above polyhydroxy demulsifier or the polyhydroxy demulsifier prepared by the above preparation method in demulsifying crude oil emulsion, including: dissolving the polyhydroxy demulsifier in solvent B to obtain a demulsifier solution, and then mixing and demulsifying it with the crude oil emulsion; the solvent B is one or more of water, ethanol, and xylene; the mass fraction of the polyhydroxy demulsifier in the demulsifier solution is 0.2 wt% - 0.6 wt%; the volume ratio of the demulsifier solution to the crude oil emulsion is 1:(10 - 20); the temperature of demulsification is 40 - 70 °C, and the time is 2 - 3 h.

[0040] The reaction formula is as follows:

[0041]

[0042] The demulsifier of the present invention uses diethyl bis(hydroxymethyl)malonate, polyalkylene polyamine, and alkylamine as raw materials to form a linear structure. This demulsifier has four hydrophilic hydroxyl groups, and the hydrophobic part is composed of the outer carbon chain, making it hydrophobic. At the same time, its long amine-containing hydrophilic chain makes it have strong hydrophilicity. Its two long carbon chains have better dispersibility in the oil phase and stronger interaction with natural interfacial active substances, which can destroy the interfacial film, promote the coalescence of water droplets, and achieve oil-water separation.

[0043] In addition, the demulsifier is prepared by connecting polyalkylene polyamine with diethyl bis(hydroxymethyl)malonate at room temperature. The synthesis steps used are simple and convenient, consume less energy, and the final product can be obtained only in two steps. The present invention provides a two-step method for synthesizing a polyhydroxy demulsifier at room temperature, which can efficiently demulsify and effectively reduce the interfacial tension between oil and water at a relatively low temperature.

[0044] This demulsifier has the advantages of simple synthesis steps, low demulsification temperature, and high demulsification efficiency. It is of great significance for solving the problems of high demulsification cost, low demulsification efficiency, and high demulsification temperature in the demulsification of crude oil emulsions in the petroleum industry. Its long amine-containing hydrophilic chain gives it strong hydrophilicity. Its two long carbon chains have better dispersibility in the oil phase and stronger interaction with natural surfactants, which can destroy the interfacial film, promote the coalescence of water droplets, and achieve oil-water separation.

[0045] In order to make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0046] In the present invention, references to "some embodiments", "this embodiment", and examples, etc., describe subsets of all possible embodiments. However, it can be understood that "some embodiments" can be the same subset or different subsets of all possible embodiments, and can be combined with each other without conflict.

[0047] If similar descriptions such as "first / second" appear in the application documents, the following explanation will be added. In the following description, the terms "first\second\third" only distinguish similar objects and do not represent a specific order for the objects. It can be understood that "first\second\third" can be interchanged in a specific order or sequence when allowed, so that the embodiments described here can be implemented in an order other than that illustrated or described here.

[0048] In this embodiment, the term "and / or" only describes the association relationship of associated objects and represents three possible relationships. For example, object A and / or object B can represent: object A exists alone, object A and object B exist simultaneously, and object B exists alone.

[0049] Hereinafter, embodiments of the present application will be described. The embodiments described below are exemplary and are only used to explain the present application and should not be construed as a limitation of the present application. For those technical or conditions not specified in the embodiments, they shall be carried out according to the techniques or conditions described in the literature in this field or according to the product specifications. For reagents or instruments not specified by the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0050] Example 1

[0051] This embodiment provides a polyhydroxy demulsifier, which has the structural formula shown in Formula I:

[0052]

[0053] This demulsifier is prepared by the following steps:

[0054] Diethyl dihydroxymethylmalonate (0.02 mol), pentaethylenehexamine (0.01 mol) and methanol (20 ml) were added to a three-necked flask and reacted at room temperature for 24 h to obtain an amidated product. Then, dodecylamine (0.02 mol) was added and the reaction continued at room temperature for 24 h. Subsequently, the temperature was raised to 60 °C and the product was obtained after distillation under reduced pressure.

[0055] Figure 1 Infrared spectrum of the demulsifier prepared in Example 1, where absorption peaks occurred at 3303 cm -1 , 2925 cm -1 , 2854 cm -1 , 1637 cm -1 , 1459 cm -1 , 1037 cm -1 representing -OH stretching vibration, -CH 2 asymmetric stretching vibration, -CH 2 symmetric vibration, C=O stretching vibration, -CH 2 bending vibration, C-N stretching vibration respectively.

[0056] Example 2

[0057] The main difference in the preparation method of the demulsifier in this example from that in Example 1 is that hexadecylamine was used to replace dodecylamine, and other steps and conditions were the same as those in Example 1.

[0058] The structural formula of the demulsifier in this example is as follows:

[0059]

[0060] This demulsifier was obtained through the following steps:

[0061] Diethyl dihydroxymethylmalonate (0.02 mol), pentaethylenehexamine (0.01 mol) and methanol (20 ml) were added to a three-necked flask and reacted at room temperature for 24 h to obtain an amidated product. Then, hexadecylamine (0.02 mol) was added and the reaction continued at room temperature for 24 h. Finally, methanol was evaporated by vacuum distillation to obtain the final product.

[0062] Figure 2 Infrared spectrum of the demulsifier prepared in Example 2, indicating the successful preparation of this demulsifier.

[0063] Example 3

[0064] The main difference in the preparation method of the demulsifier in this example from that in Example 1 is that triethylenetetramine was used to replace pentaethylenehexamine, and other steps and conditions were the same as those in Example 1.

[0065] The structural formula of the demulsifier in this embodiment is as follows:

[0066]

[0067] The demulsifier is obtained through the following steps:

[0068] Add diethyl dihydroxymethylmalonate (0.02 mol), triethylenetetramine (0.01 mol) and methanol (20 ml) into a three-necked flask, and react at room temperature for 24 h to obtain an amidation product. Then add dodecylamine (0.02 mol) and continue to react at room temperature for 24 h. Finally, evaporate methanol by vacuum distillation to obtain the final product.

[0069] Figure 3 It is the infrared spectrum of the demulsifier prepared in Example 3, indicating the successful preparation of the demulsifier.

[0070] Example 4

[0071] The main difference between Example 4 and Example 1 is that ethanol is used to replace methanol, and other steps and conditions are the same as those in Example 1.

[0072] The demulsifier is obtained through the following steps:

[0073] Add diethyl dihydroxymethylmalonate (0.02 mol), pentaethylenehexamine (0.01 mol) and ethanol (20 ml) into a three-necked flask, and react at room temperature for 24 h to obtain an amidation product. Then add dodecylamine (0.02 mol) and continue to react at room temperature for 24 h. Finally, evaporate ethanol by vacuum distillation to obtain the final product.

[0074] Figure 4 It is the infrared spectrum of the demulsifier prepared in Example 4, indicating the successful preparation of the demulsifier.

[0075] Example 5

[0076] The main difference between Example 5 and Example 1 is that the reaction time after adding dodecylamine is reduced from 24 h to 20 h, and other steps and conditions are the same as those in Example 1.

[0077] The demulsifier is obtained through the following steps:

[0078] Add diethyl dihydroxymethylmalonate (0.02 mol), pentaethylenehexamine (0.01 mol) and methanol into a three-necked flask, and react at room temperature for 24 h to obtain an amidation product. Then add dodecylamine (0.02 mol) and continue to react at room temperature for 20 h. Finally, evaporate methanol by vacuum distillation to obtain the final product.

[0079] Test Example

[0080] To avoid repetition, the crude oil emulsions used in the following tests were prepared according to the following steps:

[0081] Add 150 parts by weight of crude oil to 350 parts by weight of brine (salt content is 5%), stir and mix, heat to 60 °C, and then stir at a speed of 11,000 r / min for 20 minutes. Repeat the stirring process one to three times until a stable water-in-oil emulsion, that is, the crude oil emulsion, is obtained. To ensure the accuracy of the test, in the present invention, the crude oil emulsion with the stirring process repeated three times is used for testing, and the mixing is more uniform.

[0082] 1. Use commercial demulsifier PE10100 as Comparative Example 1, K3800 as Comparative Example 2, PDB9904 as Comparative Example 3, and DI-18 as Comparative Example 4 for comparison. Conduct a comparative test on the demulsification performance of the demulsifiers prepared in Examples 1 - 5 in the crude oil emulsion. The specific steps are as follows:

[0083] Respectively add the ionic liquids prepared in Examples 1 - 5 to xylene / ethanol (mass ratio 75:25) to prepare a solution with a mass fraction of 1%, that is, Experimental Groups 1 - 5; commercial demulsifier PE10100 is Comparative Example 1, K3800 is Comparative Example 2, PDB9904 is Comparative Example 3, and DI-18 is Comparative Example 4. Conduct a comparative experiment on Comparisons 1 - 4. Add the commercial demulsifiers in the comparative examples to xylene / ethanol (mass ratio 75:25) to prepare a solution with a mass fraction of 0.6%, that is, Comparative Groups 1 - 4;

[0084] Add Experimental Groups 1 - 5 and Comparative Groups 1 - 4 to the above-mentioned crude oil emulsion according to a volume ratio of 1:19, then fully oscillate and mix evenly, and then transfer to a 50 °C water bath and let it stand for 3 h. Measure its dehydration rate. The results are shown in Table 1.

[0085] Table 1 Demulsification results of Experimental Groups 1 - 5 and Comparative Groups 1 - 4

[0086]

[0087]

[0088] Note: "Demulsifier (mg / L)" in the table refers to the concentration of the demulsifier in the crude oil emulsion.

[0089] As can be seen from Table 1, the demulsifiers prepared in Examples 1-5 all have very good demulsification performance. However, due to different preparation conditions, such as the type of polyalkylene polyamine, the type of alkylamine hydrocarbon, the type of solvent, and the reaction time, the demulsification efficiency will vary. For example, from Examples 1 and 2, it can be seen that the further increase in the length of the hydrophobic chain is not conducive to the improvement of the demulsification efficiency. From Examples 1 and 3, it can be seen that the reduction of the hydrophilic group is not conducive to the improvement of the demulsification efficiency. The conditions in Examples 4 and 5 are different, so the demulsification efficiency is different. Compared with the commercial demulsifier in the control group, the demulsifier provided by the present invention also has more excellent demulsification ability.

[0090] 2. Solutions of the demulsifier prepared based on Example 1 with different concentrations were used to characterize the demulsification performance of the demulsifier with different concentrations in the crude oil emulsion.

[0091] The demulsifier prepared in Example 1 with different weight parts was added to a solvent of xylene / ethanol (mass ratio 75:25) to prepare demulsifiers with mass fractions of 0.2%, 0.3%, 0.4%, 0.5%, and 0.6% respectively. The obtained samples were denoted as Experimental Groups 7-11; the blank group was 0%, and the sample was denoted as Experimental Group 6.

[0092] 1 volume part of the above Experimental Groups 6-11 was added to 19 volume parts of the crude oil emulsion, then shaken well and mixed evenly, and then transferred to a water bath at 50 °C and left to stand for 3 h. The dehydration rate was measured, and the results are shown in Table 2.

[0093] Table 2 Demulsification results of Experimental Groups 6-11

[0094] Group Demulsifier (mg / L) Demulsification efficiency (%) Experimental group 6 0 0 Experimental group 7 100 60.79 Experimental group 8 150 88.88 Experimental group 9 200 96.27 Experimental group 10 250 97.24 Experimental group 11 300 98.41

[0095] Note: "Demulsifier (mg / L)" in the table refers to the concentration of the demulsifier in the crude oil emulsion.

[0096] As can be seen from Table 2, the demulsifier provided by the present invention has good demulsification performance. A demulsification efficiency of 88.88% can be achieved with a demulsifier of 150 mg / L, and when the concentration is 300 mg / L, the demulsification efficiency reaches 98.41%.

[0097] 3. Based on the demulsifier prepared in Example 1, Experimental Groups 12-15 were successively established to characterize the demulsification performance of the demulsifier at different temperatures and times.

[0098] The demulsifier prepared in Example 1 was added to a solvent of xylene / ethanol (mass ratio 75:25) to prepare a solution with a mass fraction of 0.6%.

[0099] Add 1 volume portion of the above demulsifier to 19 volume portions of the crude oil emulsion, then mix well by shaking thoroughly, and then transfer them to water baths set at different temperatures and let them stand for 3 h. Measure their dehydration rates, and the results are shown in Table 3.

[0100] Table 3 Demulsification results of experimental groups 12 - 14

[0101]

[0102]

[0103] As can be seen from Table 3: The demulsifier provided by the present invention can reach a demulsification efficiency of 97.4% in 2 h at 50 °C, a demulsification efficiency of 95.24% in 1 h at 60 °C, and a demulsification efficiency of 98.41% in 1 h at 70 °C.

[0104] In summary, the demulsifier of the present invention has the advantages of simple synthesis steps, low energy consumption, low demulsification temperature, fast demulsification rate, and high demulsification efficiency. It is of great significance for solving the problems of high demulsification cost, low demulsification efficiency, and high demulsification temperature in the demulsification of crude oil emulsions in the petroleum industry. Its long amine-containing hydrophilic chain makes it have strong hydrophilicity. Its two long carbon chains have better dispersibility in the oil phase and stronger interaction with natural surfactants, which can destroy the interfacial film, promote the coalescence of water droplets, and achieve oil-water separation.

[0105] The above specific embodiments of the present invention do not constitute a limitation to the protection scope of the present invention. Any other corresponding changes and deformations made according to the technical concept of the present invention shall be included in the protection scope of the claims of the present invention.

Claims

1. A polyhydroxy demulsifier, characterized in that It has one or more of the following structural compounds: Where x is any integer between 3 and 5, and R is C 12 -C 18 Any alkyl group in .

2. The polyhydroxy demulsifier according to claim 1, characterized in that It has one or more of the following structural compounds:

3. A method for preparing the polyhydroxy demulsifier according to any one of claims 1 to 2, characterized in that: The following steps are involved: S1, using diethyl bis(hydroxymethyl)malonate and polyethylene polyamine as raw materials, in the presence of solvent A, performing an amidation reaction to obtain an amidation product; S2, mixing the amidation product obtained in step S1 with an alkylamine to obtain the polyhydroxy demulsifier.

4. The method for preparing a polyhydroxy demulsifier according to claim 3, characterized in that: In step S1, the molar ratio of the diethyl bis(hydroxymethyl)malonate to the polyethylene polyamine is 1:(2-3).

5. The method for preparing a polyhydroxy demulsifier according to claim 3, characterized in that: In step S2, the molar ratio of the diethyl bis(hydroxymethyl)malonate to the alkylamine is 1:(1-1.5).

6. The method for preparing a polyhydroxy demulsifier according to claim 3, characterized in that: In step S1, the polyethylene polyamine is one or more of triethylenetetramine, tetraethylenepentamine, and pentaethylenehexamine; and / or, the solvent A is one or both of methanol and ethanol; and / or, in step S2, the alkylamine is one or more of dodecylamine, hexadecylamine, and octadecylamine.

7. The method for preparing a polyhydroxy demulsifier according to claim 3, characterized in that: In step S1, the amidation reaction time is 20-24 hours.

8. Use of the polyhydroxy demulsifier according to any one of claims 1 to 2 or the polyhydroxy demulsifier prepared by the preparation method according to any one of claims 3 to 7 in demulsifying crude oil emulsion.

9. The use according to claim 8, characterized in that: include: The polyhydroxy demulsifier is dissolved in solvent B to obtain a demulsifier solution, which is then mixed with the crude oil emulsion for demulsification.

10. The use according to claim 9, characterized in that: The solvent B is one or more of water, ethanol and xylene; and / or, the mass fraction of the polyhydroxy demulsifier in the demulsifier solution is 0.2wt% to 0.6wt%; and / or, the volume ratio of the demulsifier solution to the crude oil emulsion is 1:(10 to 20); and / or, the demulsification temperature is 40 to 70°C and the time is 2 to 3h.

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