Non-ionic demulsifier as well as preparation method and application thereof

Abstract

The invention discloses a nonionic demulsifier as well as a preparation method and application thereof, and belongs to the technical field of oil-water emulsion treatment. The nonionic demulsifier comprises one or more of compounds in the following structural formula: # imgabs0 # or # imgabs1 #, R is CmH2m + 2, m represents the number of carbon atoms, and m is greater than or equal to 1; n is an integer greater than or equal to 1. In addition, the invention also provides a preparation method of the nonionic demulsifier, which comprises the following steps: mixing the polyhydroxy compound, the fatty acid and the catalyst, then adding the solvent, and carrying out reflux reaction at 110-130 DEG C to obtain the nonionic demulsifier. The demulsifying efficiency of the demulsifying agent on a W / O emulsion with the oil content of 30% can reach up to 100%, and the demulsifying efficiency is high.

Description

Technical Field

[0001] The present invention relates to the technical field of oil-water emulsion treatment, and in particular to a nonionic demulsifier, a preparation method and an application thereof. Background Art

[0002] Oilfield production generates large quantities of W / O emulsions that require treatment before subsequent transportation. While conventional demulsifiers offer some demulsification effectiveness, high production costs and complex synthesis processes remain significant challenges. This not only results in energy and economic waste, but also poses risks to humans and the environment. Therefore, the development of environmentally friendly demulsifiers with simpler, lower-cost synthesis processes is urgently needed.

[0003] In addition, traditional non-ionic demulsifiers are mainly synthesized by modifying EO-PO as the main body. However, their demulsification efficiency for crude oil emulsions is not satisfactory. Moreover, the synthesis process is complicated, energy consumption is high, and the pollution is also a major disadvantage. Therefore, seeking simple, low-cost, high-efficiency and environmentally friendly demulsifiers has gradually become a research focus. Summary of the Invention

[0004] The purpose of the present invention is to overcome the above technical deficiencies, provide a nonionic demulsifier and its preparation method and application, and solve the technical problem of how to propose a new environmentally friendly demulsifier with high demulsification efficiency in the prior art.

[0005] In order to achieve the above technical objectives, the technical solution of the present invention provides a nonionic demulsifier, including one or more of the compounds in the following structural formulas:

[0006] Where R is C m H 2m+2 , m represents the number of carbon atoms, m≥1; n is an integer and n≥1.

[0007] In any embodiment, R is CH3(CH2) 16 .

[0008] In addition, the present invention also provides a preparation method of the nonionic demulsifier, comprising the following steps: mixing a polyhydroxy compound, a fatty acid and a catalyst, then adding a solvent and performing a reflux reaction at 110-130° C. to obtain the nonionic demulsifier.

[0009] In any embodiment, the molar ratio of the polyol to the fatty acid is 1:(1-1.5).

[0010] In any embodiment, the polyol is one or both of sucrose and soluble starch.

[0011] In any embodiment, the fatty acid is one or both of lauric acid and stearic acid.

[0012] In any embodiment, the catalyst is p-toluenesulfonic acid.

[0013] In any embodiment, the reflux reaction time is 4-6 hours.

[0014] In any embodiment, the reflux reaction further comprises distillation under reduced pressure to obtain the nonionic demulsifier.

[0015] In addition, the present invention also provides an application of the nonionic demulsifier or the nonionic demulsifier prepared by the above preparation method in crude oil demulsification.

[0016] Compared with the prior art, the beneficial effects of the present invention include: the demulsifier proposed by the present invention is synthesized with polyhydroxy compounds and the fatty acid as raw materials, the demulsifier is green and environmentally friendly, and the demulsification efficiency of the W / O emulsion with an oil content of 30% can be as high as 100%, and the demulsification efficiency is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 FTIR spectra (a) and (b) of the SULA demulsifier prepared in Example 1 of the present invention. 1 H NMR spectrum; Figure 1 (a) is the FTIR spectrum, Figure 1 (b) 1 H NMR spectrum.

[0018] Figure 2 FTIR spectra (a) and (b) of the SULA demulsifier prepared in Example 1 of the present invention. 1 H NMR spectrum; Figure 2 (a) is the FTIR spectrum, Figure 2 (b) 1 H NMR spectrum.

[0019] Figure 3 is the result of testing the emulsion type to be tested; Figure 3 (a) is the test result of filter paper wetting method; Figure 3 (b) is the test result of the dilution method.

[0020] Figure 4 is the effect of different factors on DE of the demulsifier of Example 1 and the emulsion viscosity at different temperatures; Figure 4 (a) Effect of temperature on ED; Figure 4 (b) is the viscosity of the emulsion at different temperatures; Figure 4 (c) is the effect of concentration on ED; Figure 4 (d) Effect of pH on ED; Figure 4 (e) is the effect of salinity on ED; Figure 4 (f) Effects of different demulsifiers on ED.

[0021] Figure 5 It is the demulsifier IFT determination diagram of Example 1; wherein Figure 5 (a) Schematic diagram of IFT assay; Figure 5 (b) IFT and corresponding schematic diagram under different concentrations of SULA demulsifier; Figure 5 (c) IFT and corresponding schematic diagram during the process of SULA demulsifier replacing asphaltene.

[0022] Figure 6 Schematic diagram of the demulsification mechanism of the demulsifier in Example 1.

[0023] Figure 7 is the effect of different factors on DE of the demulsifier of Example 2 and the emulsion viscosity at different temperatures; Figure 7 (a) Effect of temperature on ED; Figure 7 (b) is the viscosity of the emulsion at different temperatures; Figure 7 (c) is the effect of concentration on ED; Figure 7 (d) Effect of pH on ED; Figure 7 (e) is the effect of salinity on ED; Figure 7 (f) Effects of different demulsifiers on ED.

[0024] Figure 8 It is the demulsifier IFT determination diagram of Example 2; wherein Figure 8 (a) Schematic diagram of IFT assay; Figure 8 (b) IFT and corresponding schematic diagram under different concentrations of SSA demulsifier; Figure 8 (c) IFT and corresponding schematic diagram during the process of SSA demulsifier replacing asphaltene.

[0025] Figure 9 Schematic diagram of the demulsification mechanism of the demulsifier in Example 2. DETAILED DESCRIPTION

[0026] The "ranges" disclosed herein are defined in terms of lower and upper limits, where a given range is defined by selecting a lower limit and an upper limit, and the selected lower and upper limits define the boundaries of the particular range. Ranges defined in this manner can be inclusive or exclusive of the end values and can be combined arbitrarily, i.e., any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60 to 120 and 80 to 110 are listed for a particular parameter, it is understood that ranges of 60 to 110 and 80 to 120 are also contemplated. Furthermore, if minimum range values of 1 and 2 are listed, and if maximum range values of 3, 4, and 5 are listed, the following ranges are all contemplated: 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4, and 2 to 5. In this application, unless otherwise indicated, the numerical range "a to b" is a shorthand representation of any combination of real numbers between a and b, where a and b are both real numbers. For example, a numerical range of "0-5" indicates that all real numbers between "0-5" are listed herein, and "0-5" is simply an abbreviation for these numerical combinations. Furthermore, when a parameter is expressed as an integer ≥ 2, this is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0027] Unless otherwise specified, the terms "include" and "comprising" used in this application may be open-ended or closed-ended. For example, "include" and "comprising" may mean that other components not listed may also be included or that only the listed components are included.

[0028] Unless otherwise specified, the term "or" is used in this application to be inclusive. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, the condition "A or B" is satisfied if any of the following conditions are met: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0029] This embodiment provides a nonionic demulsifier, including one or more of the following compounds:

[0030] Where R is C m H 2m+2 , m represents the number of carbon atoms, m≥1; n is an integer and n≥1.

[0031] In some embodiments, R is CH3(CH2) 16 .

[0032] In addition, this specific embodiment also proposes a preparation method of the above-mentioned nonionic demulsifier, comprising the following steps: mixing a polyhydroxy compound, a fatty acid and a catalyst, then adding a solvent and reflux reacting at 110-130°C for 4-6 hours, and then removing the solvent by reduced pressure distillation to obtain the nonionic demulsifier; the molar ratio of the polyhydroxy compound to the fatty acid is 1: (1-1.5); the polyhydroxy compound is one or both of sucrose and soluble starch; the fatty acid is one or both of lauric acid and stearic acid; the catalyst is p-toluenesulfonic acid, and the amount of the toluenesulfonic acid added is 2-4% of the total mass of the polyhydroxy compound and the fatty acid; the amount of the solvent added is 15-25 ml.

[0033] This specific embodiment also proposes an application of the above nonionic demulsifier or the nonionic demulsifier prepared by the above preparation method in crude oil demulsification.

[0034] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to 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 intended to limit the present invention.

[0035] In the present invention, references to “some embodiments”, “this embodiment”, examples, etc. describe a subset of all possible embodiments, but it can be understood that “some embodiments” may be the same subset or different subsets of all possible embodiments, and may be combined with each other without conflict.

[0036] If similar descriptions of "first / second" appear in the application documents, the following explanation is added. In the following description, the terms "first\second\third" are merely used to distinguish similar objects and do not represent a specific order of the objects. It can be understood that "first\second\third" can be interchanged with the specific order or sequence where permitted, so that the embodiments described herein can be implemented in an order other than that illustrated or described herein.

[0037] In this embodiment, the term "and / or" is merely a description of the association relationship between associated objects, indicating that three relationships may exist. For example, object A and / or object B may represent three situations: object A exists alone, object A and object B exist at the same time, and object B exists alone.

[0038] Below, the embodiment of the present application is described. The embodiment described below is exemplary and is only used to explain the present application, and is not to be construed as limiting the present application. Where specific techniques or conditions are not specified in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. Reagents or instruments used that do not specify the manufacturer are conventional products that can be obtained commercially.

[0039] Example 1

[0040] This embodiment provides a nonionic demulsifier, which is prepared by the following steps:

[0041] 3.42g of sucrose and 2g of lauric acid were mixed and added to a three-necked flask. 0.19g of p-toluenesulfonic acid was added as a catalyst. 20ml of pyridine was then added as a solvent. The three-necked flask containing the mixed reactants was refluxed at 120°C for 4 hours. The pyridine was removed by vacuum distillation to obtain the synthesized nonionic demulsifier SULA. The reaction formula is as follows:

[0042]

[0043] FTIR of SULA demulsifier Figure 1 (a) shows 3340 cm -1 The broad peak near 2910 cm -1 and 2850cm -1 The characteristic peak at 1700cm is related to the stretching vibration of the C-H bond. -1 The peak at 1080 cm provides evidence for the stretching vibration of the C=O bond, while the peak at 1080 cm -1 The peak at 721 cm is related to the stretching vibration of the CO bond. -1 The peak at corresponds to the presence of –(CH2) in the long alkyl chain n -Vibration of the group.

[0044] Figure 1 (b) shows the SULA 1 H NMR spectrum. The chemical shift range of 0.9–2.27 ppm corresponds to protons H(ad) along the long alkyl chain. Peaks for protons H(eh) on the sucrose ring appear between 3.31 and 4.49 ppm. Furthermore, a peak at 5.38 ppm is associated with protons H(j) in the O—CH2—O group, while a solvent peak for methanol appears at 4.9 ppm. These results confirm the successful synthesis of the demulsifier SULA.

[0045] Example 2

[0046] This embodiment provides a nonionic demulsifier, which is prepared by the following steps:

[0047] Mix 1.8g of soluble starch and 2.84g of stearic acid in a clean, dry three-necked flask. Add 0.19g of p-toluenesulfonic acid as a catalyst, followed by 20ml of pyridine as a solvent. Heat the flask under reflux at 120°C for 6 hours. Remove the pyridine by vacuum distillation to obtain the demulsifier SSA. Stir throughout the heating process to ensure uniform mixing. The reaction formula is as follows:

[0048]

[0049] The FTIR spectrum of nonionic demulsifier SSA is as follows: Figure 2 (a) is shown. At 3380cm -1 The broad and flat peaks on the left and right belong to the stretching vibration peaks of the OH bond. The symmetrical and asymmetrical stretching vibration peaks of the CH bond are at 2910 and 2850 cm -1 At 1700cm -1 The peak at 721cm corresponds to the stretching vibration of the C=O bond. In addition, the stretching vibration peak of the CO bond appears near 1300cm-1. -1 The absorption peaks around -(CH2) n - is related to the stretching vibration of

[0050] Figure 2 (b) shows the SSA 1 H NMR spectrum. The peak of -CH3 (a) on the long-chain alkane is located at 0.82 ppm. The peaks of -CH2 (b, c) on the alkyl chain appear at 1.21-1.52 ppm. The peak at 2.2 ppm belongs to the methylene group in O=C-CH2 (d). In addition, the peak at 3.23 ppm is related to the methylene group in O-CH2 (e). Finally, the peak of the solvent MeOH is located at 4.87 ppm. In summary, FTIR and 1 The H NMR analysis further confirmed that the chemical structure of the sample belonged to the target compound, indicating that the nonionic demulsifier SSA was successfully synthesized.

[0051] Example 3

[0052] This embodiment provides a nonionic demulsifier, which is prepared by the following steps:

[0053] Sucrose and lauric acid were mixed in a molar ratio of 1:1.5 and added to a three-necked flask. The amount of sucrose was 3.44 g, and 0.19 g of toluenesulfonic acid as a catalyst was added. Then, an appropriate amount of 20 mL of pyridine was added as a solvent. Finally, the three-necked flask containing the mixed reactants was refluxed at 110° C. for 6 hours, and the pyridine was removed by vacuum distillation to obtain the synthesized nonionic demulsifier SULA.

[0054] Example 4

[0055] This embodiment provides a nonionic demulsifier, which is prepared by the following steps:

[0056] Soluble starch and stearic acid were mixed in a 1:1 molar ratio and added to a clean, dry three-necked flask. 3.41 g of soluble starch was used, along with 0.18 g of p-toluenesulfonic acid as a catalyst. An appropriate amount of 20 mL of pyridine was then added as a solvent. The three-necked flask was then refluxed and heated at 130°C for 5 hours. After heating, the pyridine was removed by vacuum distillation to obtain the demulsifier SSA. Stirring was required throughout the heating process to ensure uniform mixing of the reactants.

[0057] Comparative Example 1

[0058] The demulsifier of this comparative example differs from that of Example 1 in that sucrose is replaced by polyethylene glycol 600, and the other raw materials and reaction conditions are the same as those of Example 1 to prepare the demulsifier.

[0059] Comparative Example 2

[0060] The demulsifier of this comparative example differs from that of Example 1 in that lauric acid is replaced by caprylic acid, and the other raw materials and reaction conditions are the same as those of Example 1 to prepare the demulsifier.

[0061] Comparative Example 3

[0062] The demulsifier of this comparative example differs from that of Example 2 in that capric acid is used instead of stearic acid. Other raw materials and reaction conditions are the same as those of Example 2 to prepare the demulsifier.

[0063] Preparation of W / O emulsion and demulsification performance experiment

[0064] A W / O emulsion with a 30% oil content was prepared. Crude oil and distilled water were mixed in a mass ratio of 3:7. The mixture was then heated for 30 minutes and stirred at 11,000 rpm / min using a homogenizer (FJ200) for 20 minutes to obtain a homogenous W / O emulsion. The emulsion was stable for at least one week at the test temperature.

[0065] Before conducting the demulsification performance test, the type of emulsion to be tested is identified and tested using the filter paper wetting and dilution method. Specifically, 1 mL of emulsion is dropped on the filter paper and left to stand for a few minutes. Figure 3 As shown in (a), it can be seen that the emulsion does not disperse and only a small amount of water can wet the filter paper. In addition, 1 mL of the emulsion is added to 20 mL of distilled water, then shaken and allowed to stand. Figure 3 As shown in (b), the emulsion still remains in an aggregated state and is not dispersed in water. In summary, the above proves that the emulsion belongs to the W / O type.

[0066] The demulsification performance experiment was carried out in accordance with SY / T 5280-2018 "General Technical Conditions for Crude Oil Demulsifiers". The demulsification performance of SULA was evaluated using a test bottle test. Initially, demulsifiers with different conditions were prepared as needed and dissolved in anhydrous ethanol to obtain a demulsifier solution. Subsequently, the demulsifier solution and the emulsion were taken in a test bottle at a ratio of 1:19 and thoroughly mixed. At this time, anhydrous ethanol was used instead of the demulsifier solution and prepared in the same way as a blank control. Before the test, the bottle was heated in a water bath for 5 minutes and then shaken vigorously for 2 minutes to ensure that the demulsifier and the emulsion were evenly mixed. The bottle was then returned to the water bath to observe the oil-water separation. Each group was repeated 3 times, and the demulsification efficiency of the demulsifier was calculated according to the following formula:

[0067]

[0068] In the formula, DE (%) represents the demulsification efficiency of the emulsion, V1 and H1 represent the volume and height of the water layer after demulsification, respectively. V0 and H0 represent the volume and height of the emulsion before demulsification. S represents the cross-sectional area of the test bottle.

[0069] Experimental analysis of demulsification performance

[0070] The bottle test method was used to systematically study the effects of temperature, concentration, pH value, salinity and other factors on the demulsification performance of SULA. Figure 4 The relationship between temperature and DE is shown in Figure 2. It is obvious that DE increases with increasing temperature. This phenomenon can be attributed to two main factors. On the one hand, increasing temperature will reduce the viscosity of W / O emulsion, such as Figure 4 (b) shows that this promotes the rapid separation and coalescence of emulsion droplets. On the other hand, increasing the temperature accelerates the movement of demulsifier molecules, enabling them to reach the oil-water interface faster, thereby promoting the demulsification process. Figure 4 (c) shows the effect of SULA concentration on DE at 50°C. Increasing SULA concentration corresponds to a decrease in demulsification time and an increase in DE. When SULA concentration is below 400 mg / L, DE remains at 0, indicating that low SULA concentrations are ineffective for demulsification. However, when SULA concentration exceeds 600 mg / L, DE increases significantly. Notably, DE rapidly reaches 100% at SULA concentrations of 1000 mg / L.

[0071] Figure 4 (d) SULA shows a DE of 0 under strongly acidic conditions (pH = 2). This phenomenon may be related to the protonation of SULA molecules in a strongly acidic environment, which hinders its demulsification process. However, it is encouraging to see that a significant DE is present over a wide pH range (4-12) with no significant difference. This demonstrates the wide pH adaptability of SULA. Figure 4(e) illustrates the effect of salinity on DE. As salinity increases from 0 to 100,000 mg / L, the DE remains stable at 100%. This phenomenon is likely attributed to the presence of salt ions in the emulsion, which neutralize the ions, weaken the electrostatic repulsion between droplets, and promote emulsion demulsification. In summary, SULA exhibits excellent pH adaptability and salt tolerance.

[0072] Finally, SULA was compared with commercial demulsifiers. SULA and various commercial demulsifiers were added to W / O emulsions and evaluated for DE under the same test conditions. Figure 4 (f) shows that SULA exhibits superior demulsification ability compared to other demulsifiers, producing a clearly separated aqueous phase. Notably, DI-18 has a DE of 0, while PDB9958 and K3800 have DEs of approximately 60%, resulting in turbidity and wall-hanging in their respective aqueous phases. Although L64 and PDB9360 both have DEs exceeding 90%, they are still slightly lower than SULA. Overall, SULA has an absolute advantage in emulsification processes, demonstrating its enormous potential for application.

[0073] Interfacial tension (IFT)

[0074] Interfacial tension (IFT) can be used to evaluate the adsorption capacity of demulsifiers at the oil-water interface. IFT values at different concentrations are measured using the pendant drop method. Figure 5 (a) shows a schematic diagram of the IFT measurement process. The measurement data are shown in Figure 5 As shown in (b), it is easy to see that the IFT value decreases with increasing concentration. Specifically, as the SULA concentration increases from 200 mg / L to 1000 mg / L, the IFT decreases from 16.89 mN / m to 3.52 mN / m. During this process, the adsorption of SULA can be divided into three different stages. Initially, SULA freely diffuses and rapidly adsorbs at the oil-water interface, causing the IFT to decrease rapidly. In the intermediate stage, a large amount of SULA occupies the oil-water interface, inhibiting further adsorption of SULA and causing the IFT to decrease more slowly. Eventually, the adsorption reaches saturation, and the IFT shows a state of dynamic equilibrium.

[0075] To further investigate the competitive adsorption between SULA and asphaltene, we measured the changes in IFT after SULA was added dropwise to asphaltene solution. Figure 5 As shown in Figure (c), the IFT of the pure asphaltene solution decreased from 41.79 mN / m to 35.62 mN / m. In contrast, the addition of SULA caused a rapid decrease in the IFT before gradually reaching equilibrium around 29.3 mN / m. This indicates that SULA effectively reduces the IFT value, demonstrating its superior interfacial activity compared to asphaltene, leading to its active role in competitive adsorption.

[0076] The demulsification principle of the demulsifier of Example 1 is analyzed as follows:

[0077] Based on the above results, possible demulsification mechanisms are proposed, such as Figure 6 As shown in the figure, the bright areas in the original emulsion correspond to the water droplets in the emulsion, while the dark areas belong to the oil phase. The water droplets are clearly evenly distributed throughout the oil phase, confirming that the original emulsion is a stable W / O emulsion. After the demulsifier is added, the dispersed small water droplets gradually converge and aggregate to form larger droplets, which then sink under gravity, leaving the oil phase distributed above. Finally, the demulsified water phase is examined, revealing a small number of black spots, likely representing small amounts of solid matter carried over from the oil phase.

[0078] Thanks to its amphiphilic structure and strong interfacial activity, the demulsifier rapidly migrates to the oil-water interface and adsorbs. It then displaces the naturally occurring active substances present at the interface, reducing the interfacial tension of the emulsion system and weakening the interfacial membrane, thus promoting demulsification. Furthermore, during the demulsification process, larger water droplets can be observed agglomerating into larger droplets, ultimately separating the oil and water under the influence of gravity. The demulsified aqueous phase contains only a small number of oil droplets.

[0079] The demulsification performance of the SSA demulsifier prepared in Example 2 was evaluated by the bottle test method.

[0080] Specifically, the effects of temperature, concentration, pH value, salinity and other factors on the demulsification efficiency (DE) of SSA were studied. In addition, the viscosity of the emulsion was measured as a function of temperature. Figure 7 The effect of SSA concentration on DE is shown in Figure 7 (a), the blank sample (no demulsifier added) did not undergo oil-water separation. This is because the rigid interfacial film formed by asphaltene hinders the aggregation of the water phase. When the demulsifier concentration is increased to 200 mg / L, DE is still 0. This is because at low concentrations, only a small amount of demulsifier reacts with asphaltene and cannot destroy the rigid interfacial film. When the concentration is increased to 500 mg / L, DE gradually increases from the initial 0 to 94.26%. In addition, it can be seen that increasing the demulsifier concentration not only promotes emulsion demulsification but also shortens the demulsification time. This is because increasing the concentration will cause a large amount of demulsifier to reach the oil-water interface faster to replace asphaltene, transforming the stable rigid interfacial film into an unstable composite film, and ultimately causing it to become unstable and rupture to complete oil-water separation. Secondly, the effect of temperature on DE was explored, and the results are as follows. Figure 7 (b) It is obvious that DE increases with increasing temperature and finally reaches a dynamic equilibrium. This is because increasing the temperature will further reduce the viscosity of the emulsion (e.g. Figure 7 (c)), On the other hand, increasing the temperature accelerates the movement of demulsifier and water droplets, making the demulsifier reach the oil-water interface faster to destroy the rigid interfacial film and promote the coalescence of water droplets.

[0081] Then the demulsification of SSA at different pH and salinity was analyzed. Figure 7 (d) and 7(e). SSA has a high DE (more than 82%) in a wide pH range (2-12). Compared with neutral conditions, the DE is slightly reduced in acidic and alkaline environments. This may be due to the protonation and deprotonation of SSA molecules in acidic and alkaline environments, which affects the migration speed and demulsification effect of SSA. In addition, positive and negative charges enhance the rigid interface film of asphaltene, which also weakens the demulsification ability of SSA. It can be clearly seen that when the salinity increases from 0 mg / L to 50000 mg / L, the DE increases from 94.26% to 100%. This shows that the addition of NaCl can promote the demulsification of emulsions by SSA. This is because NaCl ions reduce the electric field strength of the emulsion, thereby reducing the electrostatic repulsion, which promotes the demulsification of the emulsion. In addition, NaCl can also reduce interfacial tension and further accelerate the coalescence of water droplets.

[0082] Finally, SSA was compared with commercial demulsifiers. SSA and each commercial demulsifier were tested under the same conditions. The results are as follows: Figure 7 (f). SSA's DE is 94.26%, significantly higher than other commercial demulsifiers. Most commercial demulsifiers are based on ethylene oxide (EO) and propylene oxide (PO), resulting in high production costs and a highly uncertain reaction process. In comparison, SSA offers significant advantages. In summary, SSA not only exhibits excellent DE but also possesses strong acid, alkali, and salt resistance.

[0083] The adsorption capacity of demulsifiers at the oil-water interface can be expressed through interfacial tension (IFT). According to research, demulsifiers with excellent demulsification performance have high interfacial activity and low IFT. Using xylene as the oil phase, the IFT of different concentrations of SSA and substituted asphaltene was measured using the pendant drop method. The measuring device is as follows: Figure 8 (a) shows the result. Figure 8 (b) and 8(c). Figure 8 In (b), the IFT of 100 mg / L SSA is 25.2 mN / m at 1200 s, while the IFT of 500 mg / L SSA drops to 14.35 mN / m. It can be seen that the IFT decreases more with increasing SSA concentration, indicating that SSA's ability to reduce IFT increases with increasing concentration. Furthermore, the process of SSA reducing IFT can be divided into three stages. Initially, SSA freely diffuses to the oil-water interface and adsorbs on the surface, causing a rapid decrease in IFT. As SSA adsorbs, steric hindrance gradually increases, hindering further SSA adsorption and slowing the rate of IFT reduction. Finally, SSA adsorption approaches saturation, and the IFT is in a stable equilibrium state.

[0084] Figure 8(c) shows the change in IFT as SSA replaces asphaltene, demonstrating the demulsifier's ability to displace asphaltene. The asphaltene's IFT decreases from 42.79 mN / m to 36.62 mN / m. After the addition of the SSA solution at 600 s, the IFT rapidly decreases, ultimately stabilizing at around 27.8 mN / m. Before the demulsifier is added, asphaltene forms a stable, rigid interfacial film at the oil-water interface. After the addition of SSA, SSA rapidly reaches the interface and displaces asphaltene, resulting in a significant decrease in IFT. This not only demonstrates SSA's dominant position in competitive adsorption with asphaltene, but also demonstrates its higher interfacial activity than asphaltene.

[0085] Through comprehensive analysis of the above experiments, a possible demulsification mechanism can be proposed. The microscopic state of crude oil emulsion and SSA demulsification process was observed under a microscope. The results are as follows Figure 9 As shown in the figure, in the W / O emulsion micrograph, the bright spots represent the aqueous phase, while the dark areas represent the oil phase. The uniform distribution of water droplets throughout the oil phase clearly demonstrates the stability of the W / O emulsion and its resistance to oil-water separation. Upon addition of the SSA demulsifier, small water droplets can be observed to gradually coalesce into larger droplets or clusters. This is due to the rapid migration of the SSA toward the oil-water interface, disrupting the interfacial membrane and promoting droplet coalescence. Once introduced into the emulsion, the SSA, with its excellent interfacial activity and ability to significantly reduce the interfacial tension (IFT), competes with asphaltene for adsorption. This interaction transforms the tough, rigid interfacial membrane into a composite membrane, accelerating its rupture and promoting coalescence of the aqueous phase and oil-water phase separation. It is worth noting that the oil phase has a lower density than the aqueous phase. Therefore, during oil-water phase separation, the aqueous phase gradually sinks under the influence of gravity, while the oil phase concentrates above the aqueous phase, achieving complete oil-water separation.

[0086] The demulsifiers of Examples 3-4 and Comparative Examples 1-3 were subjected to the demulsification performance test of Example 1 to analyze their ED. The ED of the demulsifier at a concentration of 1000 mg / L at 50° C. was tested. The results are shown in Table 1.

[0087] Table 1

[0088] ED (%) Example 3 100 Example 4 100 Comparative Example 1 81.5 Comparative Example 2 92.7 Comparative Example 3 90.3

[0089] As can be seen from Table 1, although the demulsifiers of Comparative Examples 1-3 also have a certain demulsification effect, their demulsification efficiency is lower than that of the demulsifiers of Examples 3-4.

[0090] Other beneficial effects:

[0091] 1) The demulsification performance study of SULA demulsifier shows that 1000 mg / L SULA can achieve 100% demulsification efficiency for 30% oil content W / O emulsion at a low temperature of 50°C, and it also has excellent pH adaptability and salt tolerance.

[0092] 2) Characterization and analysis, including zeta potential, interfacial tension, three-phase contact angle, and coalescence time, indicate that SULA exhibits greater interfacial activity and stronger adsorption capacity than asphaltenes. The addition of SULA weakens the stability of the interfacial film, promotes droplet decomposition, and ultimately leads to oil-water separation.

[0093] 3) SULA is synthesized from low-cost, widely available raw materials, achieving environmental protection goals. As an environmentally friendly demulsifier with a simple synthesis process, it exhibits excellent dehydration capabilities, giving it great potential for application in oilfield demulsification technology.

[0094] 4) The demulsification performance study of SSA demulsifier shows that the demulsification efficiency of 500 mg / L SSA for 30% oil content W / O emulsion reaches 94.26% at a low temperature of 50°C. In addition, it has excellent acid and alkali resistance (2-12) and salt resistance (50000 mg / L).

[0095] 5) Characterization and analysis, including zeta potential, interfacial tension, three-phase contact angle, and rupture time, demonstrate that SSA exhibits greater interfacial activity and stronger adsorption capacity than asphaltenes. SSA can effectively displace asphaltenes from emulsions, transforming the rigid interfacial membrane into an unstable composite membrane, reducing its strength and promoting demulsification, ultimately achieving oil-water separation.

[0096] 6) SSA is synthesized from environmentally friendly raw materials, with a simple synthesis process and excellent demulsification performance. These advantages have made SSA a key player in demulsification technology in the petroleum industry. This research also provides an innovative direction and reference for the development of environmentally friendly demulsifiers synthesized from natural products.

[0097] The specific embodiments of the present invention described above do not limit the scope of protection of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the scope of protection of the claims of the present invention.

Claims

1. A nonionic demulsifier, characterized in that: Including one or more of the compounds in the following structural formulas: Where R is C m H 2m+2 , m represents the number of carbon atoms, m≥1; n is an integer and n≥1.

2. The nonionic demulsifier according to claim 1, characterized in that R is CH3(CH2) 16 .

3. A method for preparing the nonionic demulsifier according to any one of claims 1 to 2, characterized in that: The method comprises the following steps: mixing a polyhydroxy compound, a fatty acid and a catalyst, then adding a solvent and performing a reflux reaction at 110-130 DEG C to obtain the nonionic demulsifier.

4. The method for preparing the nonionic demulsifier according to claim 3, wherein The molar ratio of the polyhydroxy compound to the fatty acid is 1:(1-1.5).

5. The method for preparing the nonionic demulsifier according to claim 3, wherein The polyhydroxy compound is one or both of sucrose and soluble starch.

6. The method for preparing the nonionic demulsifier according to claim 3, wherein: The fatty acid is one or both of lauric acid and stearic acid.

7. The method for preparing the nonionic demulsifier according to claim 3, wherein The catalyst is p-toluenesulfonic acid.

8. The method for preparing the nonionic demulsifier according to claim 3, wherein The reflux reaction time is 4-6 hours.

9. The method for preparing the nonionic demulsifier according to claim 3, wherein: After the reflux reaction, the method further comprises the step of vacuum distillation to obtain the nonionic demulsifier.

10. Use of the nonionic demulsifier according to any one of claims 1 to 2 or the nonionic demulsifier prepared by the preparation method according to any one of claims 3 to 9 in crude oil demulsification.

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