Crude oil demulsifier as well as preparation method and application thereof

Abstract

The invention relates to the technical field of demulsifiers, in particular to a crude oil demulsifier as well as a preparation method and application thereof. The crude oil demulsifier contains polyether modified organic silicon, amine-terminated polyether, a nano titanium dioxide-graphene compound, polyoxyethylene fatty acid, ammonium persulfate and a novel sulfobetaine derivative; the components are mixed according to a specific proportion; the nano titanium dioxide-graphene compound is prepared through a unique reaction, and the derivative also has an exclusive synthesis path; the demulsifier can reduce interfacial tension, decompose impurities through photocatalysis, adapt to complex crude oil and improve the demulsification effect. The demulsification efficiency is high, the dehydration rate exceeds 90%, and the desalination rate exceeds 80%; the adaptability to high-salt and high-acid-value crude oil is high, organic impurities can be photolyzed, and the quality of the crude oil is improved; and the environment-friendly property is good, and efficient and green development of crude oil extraction and processing is promoted.

Description

Technical Field

[0001] The invention relates to the technical field of demulsifiers, in particular to a crude oil demulsifier and a preparation method and application thereof. Background Art

[0002] Crude oil demulsification is a crucial link in the process of crude oil extraction and processing. Crude oil is usually extracted in the form of oil-water emulsion. The presence of water not only increases transportation costs, but may also cause problems such as pipeline corrosion and equipment scaling, seriously affecting the subsequent processing of crude oil and product quality. Traditional crude oil demulsifiers have exposed many limitations when dealing with the increasingly complex crude oil extraction environment and diverse crude oil properties.

[0003] Early crude oil demulsifiers were mainly simple surfactants, such as fatty acid salts. Although this type of demulsifier can reduce the oil-water interfacial tension to a certain extent, it has low demulsification efficiency and a narrow scope of application. It often has poor effects on crude oil systems with high water content and complex emulsification. With the development of technology, polyether demulsifiers have been widely used. Polyether demulsifiers achieve demulsification by changing the properties of the oil-water interfacial film. However, its adaptability to crude oils of different origins and different compositions still needs to be improved. The natural emulsifier components such as asphaltene and colloid contained in different crude oils vary greatly, and conventional polyether demulsifiers are difficult to deal with effectively, and incomplete demulsification and low dehydration and desalination rates often occur.

[0004] In offshore crude oil production, the salt content of crude oil emulsion increases significantly due to the mixing of seawater, and the temperature and pressure changes in the production environment are complex; the performance of existing demulsifiers will be significantly affected under high salt and variable temperature and pressure conditions, and the demulsification effect will be greatly reduced; in addition, with increasingly stringent environmental protection requirements, the oily wastewater generated during crude oil demulsification will cause serious pollution to the environment if not handled properly; after traditional demulsifiers are used for demulsification, the demulsifier components remaining in the wastewater may interfere with subsequent wastewater treatment processes, and even cause microbial poisoning, affecting the wastewater treatment effect.

[0005] Moreover, crude oil often contains a variety of organic impurities, such as aromatics, cycloalkanes, etc. These impurities not only affect the quality of crude oil, but also increase the difficulty of demulsification; most of the existing demulsifiers only focus on oil-water separation and lack the ability to handle organic impurities in crude oil; at the same time, in some special crude oil production, such as heavy oil production, the crude oil has high viscosity and poor fluidity, and the existing demulsifiers are difficult to quickly and efficiently penetrate into the oil-water interface, and the demulsification time is long and the efficiency is low; therefore, it is urgent to develop a new type of crude oil demulsifier with high demulsification efficiency, wide applicability, ability to handle organic impurities and environmental protection; this patent is aimed at the deficiencies of these existing technologies, and through innovative component design and preparation methods, aims to provide a crude oil demulsifier with excellent performance to meet the urgent needs of the current crude oil production and processing industry. Summary of the invention

[0006] 1. Technical issues to be resolved

[0007] In view of the deficiencies in the prior art, the present invention provides a crude oil demulsifier and a preparation method and application thereof.

[0008] (II) Technical solution

[0009] A crude oil demulsifier is composed of polyether-modified silicone, amino-terminated polyether, nano titanium dioxide-graphene composite, fatty acid polyoxyethylene ester, initiator ammonium persulfate and novel zwitterionic surfactant sulfonate betaine derivative; wherein the mass fraction of polyether-modified silicone is 30%-45%, the mass fraction of amino-terminated polyether is 25%-35%, the mass fraction of nano titanium dioxide-graphene composite is 15%-25%, the mass fraction of fatty acid polyoxyethylene ester is 5%-10%, the mass fraction of initiator ammonium persulfate is 0.5%-2%, and the mass fraction of novel zwitterionic surfactant sulfonate betaine derivative is 3%-8%; the nano titanium dioxide-graphene composite is prepared by hydrolyzing TiOCl2 to generate TiO2 nanoparticles, and simultaneously reducing graphene oxide to reduced graphene rGO by hydrazine hydrate, and finally loading the TiO2 nanoparticles on the surface of rGO, and the reaction formula can be simplified as follows:

[0010]

[0011] The novel zwitterionic surfactant sulfonate betaine derivative is prepared by reacting N,N-dimethylaminopropylamine with 1,3-propane sultone under heating conditions. The chemical structural formula of the sulfonate betaine derivative is:

[0012]

[0013] The chemical reaction formula for its preparation is specifically:

[0014]

[0015] The crude oil demulsifier of the present invention can significantly reduce the surface tension of the oil-water interface and improve the demulsification efficiency through the synergistic effect of various components; the nano titanium dioxide-graphene composite has photocatalytic performance under light irradiation and can decompose some organic impurities in the crude oil; the new zwitterionic surfactant can form a special double electric layer structure at the oil-water interface to enhance the demulsification effect, and at the same time has better adaptability to high-salt and high-acid crude oil.

[0016] Preferably, in the polyether-modified silicone, the relative molecular mass of the polyether segment is 1000-3000, the degree of polymerization of the siloxane segment is 20-50, and the end of the polyether segment is grafted with a pH-responsive carboxylate group, so that its hydrophilicity can be adjusted under different pH environments.

[0017] Preferably, the amine value of the amino-terminated polyether is 400-600 mgKOH / g, the relative molecular mass is 2000-4000, and a fluorinated alkyl side chain is introduced into the amino-terminated polyether molecule to enhance its solubility and interfacial activity in the oil phase.

[0018] Preferably, in the nano-titanium dioxide-graphene composite, the particle size of the nano-titanium dioxide is 10-50nm, the thickness of the graphene sheet is 1-5nm, and the nano-titanium dioxide is uniformly loaded on the surface of the graphene sheet. The graphene sheet is nitrogen-doped to improve its electron transport capacity and enhance its photocatalytic activity.

[0019] Preferably, in the fatty acid polyoxyethylene ester, the carbon chain length of the fatty acid is 12-18, the degree of polymerization of the polyoxyethylene chain is 5-15, and the fatty acid part contains unsaturated double bonds, which can participate in free radical polymerization reaction and improve the stability of the demulsifier.

[0020] Preferably, in the novel zwitterionic surfactant sulfonate betaine derivative, the alkyl chain length in the molecular structure is 8-12, and a functional group that can form a complex with specific impurities in crude oil is introduced on the quaternary ammonium nitrogen atom, further improving the demulsification effect.

[0021] Preferably, a method for preparing a crude oil demulsifier comprises the following steps: adding polyether-modified silicone and amino-terminated polyether into a reaction kettle, stirring and mixing at 50-70°C for 30-60 minutes at a stirring speed of 200-400r / min; adding nano-titanium dioxide-graphene composite, continuing stirring for 60-90 minutes to fully mix the components; adding fatty acid polyoxyethylene ester and initiator ammonium persulfate, reacting at 80-100°C for 2-4 hours; adding a novel zwitterionic surfactant sulfonate betaine derivative 30 minutes before the end of the reaction, and continuing the reaction until the end; after the reaction is completed, cooling to room temperature to obtain the crude oil demulsifier.

[0022] Preferably, an application of a crude oil demulsifier in a crude oil dehydration and desalination process is characterized in that: the crude oil demulsifier is added to the crude oil at a concentration of 50-200 mg / L, and allowed to stand at 40-60°C for 1-3 hours to achieve demulsification, dehydration and desalination of the crude oil; for crude oil with a high acid value, the pH of the crude oil can be adjusted to 6-8 before adding the demulsifier to further improve the demulsification efficiency.

[0023] Preferably, the water content of the crude oil is 10%-30%, the salt content is 500-5000 mg / L, and the acid value is 1-10 mgKOH / g.

[0024] Preferably, after using the crude oil demulsifier, the dehydration rate of the crude oil is not less than 90%, and the desalination rate is not less than 80%. For crude oil with a high acid value of 5-10 mgKOH / g, the dehydration rate can still reach more than 85%, and the desalination rate is not less than 75%.

[0025] (III) Beneficial technical effects

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. Through the synergistic effect of components such as polyether modified silicone, amino-terminated polyether, nano-titanium dioxide-graphene composite, fatty acid polyoxyethylene ester and new zwitterionic surfactant sulfonic acid betaine derivative, the surface tension of the oil-water interface can be quickly reduced; experiments show that after using this patented demulsifier, the dehydration rate of crude oil is not less than 90%, and the desalination rate is not less than 80%. Compared with traditional demulsifiers, the dehydration and desalination efficiency is increased by 20%-30%, which greatly shortens the demulsification time and improves the efficiency of crude oil extraction and processing.

[0028] 2. The new zwitterionic surfactant can form a special double-layer structure at the oil-water interface, and has good adaptability to crude oils of different properties, especially high-salt and high-acid crude oils; for high-acid crude oils with an acid value of 5-10 mgKOH / g, the dehydration rate can still reach more than 85%, and the desalination rate is not less than 75%, which effectively solves the problem of traditional demulsifiers in treating such crude oils.

[0029] 3. Under light conditions, it can decompose organic impurities such as aromatics and cycloalkanes in crude oil, which not only improves the quality of crude oil, but also reduces the viscosity of crude oil, making the demulsification process smoother; at the same time, the pH-responsive carboxylic acid ester group of polyether-modified silicone, the fluorinated alkyl side chain of terminal amino polyether and the unsaturated double bond of fatty acid polyoxyethylene ester further enhance the performance stability and interfacial activity of the demulsifier under different environments.

[0030] 4. After the demulsifier of the present invention breaks the emulsion, the residual components in the sewage have little interference with the subsequent sewage treatment process, which is conducive to environmentally friendly sewage treatment and reduces the risk of environmental pollution; in addition, the reaction conditions in the preparation process of the demulsifier are mild, the energy consumption is low, and it is in line with the concept of green chemistry; in short, the crude oil demulsifier of this patent provides a high-efficiency, environmentally friendly, and highly adaptable solution for the crude oil mining and processing industry, and has broad application prospects and significant economic and social benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a preparation flow chart of the crude oil demulsifier proposed by the present invention;

[0032] Figure 2 It is a radar comparison chart made after unifying the dimensions of the function and stability experimental data of the embodiment and the comparative example;

[0033] Figure 3 It is a comparison diagram of efficiency and economy of the embodiment and the comparative example;

[0034] Figure 4 It is a bar chart comparing the basic performance of the embodiment and the comparative example;

[0035] Figure 5 The nuclear magnetic resonance spectrum of the sulfobetaine derivative proposed by the present invention. DETAILED DESCRIPTION

[0036] Example 1

[0037] Raw materials preparation:

[0038] The polyether-modified silicone accounts for 40%, and the relative molecular mass of the polyether segment is 2000, the degree of polymerization of the siloxane segment is 30, and it contains pH-responsive carboxylate groups. The relative molecular mass of the polyether segment and the degree of polymerization of the siloxane segment are detected by hydrogen nuclear magnetic resonance spectroscopy and gel permeation chromatography, and the presence and content of the carboxylate group are confirmed by Fourier transform infrared spectroscopy.

[0039] The amino-terminated polyether accounts for 30%, the amine value is 500mgKOH / g, the relative molecular mass is 3000, and it contains fluorinated alkyl side chains. The amine value is determined by acid-base titration, the relative molecular mass is determined by gel permeation chromatography, and the fluorine content is verified by elemental analysis;

[0040] The nano-titanium dioxide-graphene composite accounts for 20%, wherein the nano-titanium dioxide particle size is 30nm, and the graphene sheet thickness is 3nm and is nitrogen-doped. During the preparation, tetrabutyl titanate is hydrolyzed in an ethanol solution to generate a titanium dioxide precursor, which is then mixed with graphene oxide that has been subjected to ultrasonic exfoliation and nitrogen doping treatment, and then reduced with hydrazine hydrate to obtain the composite structure. The composite structure is observed with a transmission electron microscope, and the nitrogen doping is verified by X-ray photoelectron spectroscopy.

[0041] Fatty acid polyoxyethylene esters account for 7%, the fatty acid carbon chain length is 16, the polyoxyethylene chain polymerization degree is 10 and contains unsaturated double bonds. The carbon chain length needs to be analyzed by gas chromatography-mass spectrometry, the hydroxyl value is measured to calculate the polyoxyethylene chain polymerization degree, and the double bonds are qualitatively analyzed by infrared spectroscopy;

[0042] The new zwitterionic surfactant accounts for 5%, with an alkyl chain length of 10 and a quaternary ammonium nitrogen atom containing a specific functional group. It needs to be prepared by reacting N,N-dimethylaminopropylamine with 1,3-propanesultone in an organic solvent according to the reaction formula. The product structure is verified by nuclear magnetic resonance carbon spectroscopy and electrospray ionization mass spectrometry;

[0043] The initiator ammonium persulfate accounts for 1%, and the analytical grade reagent is purchased directly;

[0044] The nano-titanium dioxide-graphene composite and the new zwitterionic surfactant must be prepared in advance according to the established reaction formula and conditions, and the temperature and reaction time must be strictly controlled during the preparation process.

[0045] Preparation process

[0046] Add polyether-modified silicone and amino-terminated polyether into a reactor with high-precision temperature control and variable frequency stirring functions, set the temperature to 60°C, adjust the stirring speed to 300r / min, and mix for 45 minutes. During the mixing process, use a rotational rheometer to detect the viscosity change of the material every 10 minutes to determine the degree of mixing uniformity;

[0047] Add nano-titanium dioxide-graphene composite and keep stirring for 75 minutes. During this period, use a laser particle size analyzer to monitor the dispersion particle size changes of the composite in the system in real time, and adjust the stirring speed and time to ensure that the composite is evenly dispersed;

[0048] Add fatty acid polyoxyethylene ester and initiator ammonium persulfate, raise the temperature to 90°C, and react for 3 hours. During the reaction, use high performance liquid chromatography to detect the content changes of each component in the reaction system every half an hour, and draw a reaction progress curve;

[0049] 30 minutes before the end of the reaction, a new zwitterionic surfactant was added. After the reaction, the contents of the reactor were cooled to room temperature using a circulating water cooling device to obtain a crude oil demulsifier. The appearance changes and stability of the demulsifier were monitored during the cooling process.

[0050] Performance Testing

[0051] Select crude oil with a water content of 20%, a salt content of 2000 mg / L, and an acid value of 3 mgKOH / g, add 120 mg / L of demulsifier, place it in a graduated glass reaction container, and place it in a constant temperature water bath of 50 degrees Celsius with an accuracy of ±0.5 degrees Celsius for 2 hours. The test results are as follows:

[0052] The dehydration rate was determined by centrifugal separation. The mixture after demulsification was centrifuged at 4000 rpm for 15 minutes, the volume of the separated water phase was measured and the dehydration rate was calculated to be 93%; the desalination rate was determined by potentiometric titration, and the desalination rate was 83% by comparing the change in salt content in the crude oil before and after demulsification; the decomposition of organic impurities was analyzed by gas chromatography-mass spectrometry to analyze the changes in the content of organic impurities such as aromatics and cycloalkanes in the crude oil before and after demulsification, and the results showed that the impurity content was reduced; the change in crude oil viscosity was determined by a rotational viscometer at 30 degrees Celsius. After demulsification, the viscosity of the crude oil decreased and the fluidity was significantly enhanced.

[0053] Example 2

[0054] Raw material preparation

[0055] The polyether-modified silicone accounts for 35%, the relative molecular mass of the polyether segment is 1500, the degree of polymerization of the siloxane segment is 25, and it contains pH-responsive carboxylate groups. The parameters of the polyether segment and the siloxane segment are detected by hydrogen nuclear magnetic resonance spectrum and gel permeation chromatography, and the carboxylate group is analyzed by Fourier transform infrared spectroscopy.

[0056] The amino-terminated polyether accounts for 32%, the amine value is 450mgKOH / g, the relative molecular mass is 2500, and it contains fluoroalkyl side chains. The amine value needs to be determined by acid-base titration, the molecular weight needs to be determined by gel permeation chromatography, and the presence of fluoroalkyl side chains needs to be confirmed by elemental analysis;

[0057] Nano-titanium dioxide-graphene composites account for 22%, of which nano-titanium dioxide has a particle size of 20 nanometers and graphene sheets are 2 nanometers thick and nitrogen-doped. They need to be prepared according to a specific process. The particle size and sheet thickness of the composite are observed by transmission electron microscopy, and the nitrogen doping is verified by X-ray photoelectron spectroscopy;

[0058] Fatty acid polyoxyethylene esters account for 6%, with a fatty acid carbon chain length of 14 and a polyoxyethylene chain polymerization degree of 8, containing unsaturated double bonds. The carbon chain length needs to be analyzed by gas chromatography-mass spectrometry, the hydroxyl value needs to be measured to calculate the polymerization degree, and the presence of double bonds needs to be confirmed by infrared spectroscopy;

[0059] The new zwitterionic surfactant accounts for 4%, the alkyl chain length is 9, and the quaternary ammonium nitrogen atom contains a specific functional group. It needs to be synthesized according to the reaction formula, and the structure and purity must be verified by nuclear magnetic resonance carbon spectroscopy and electrospray ionization mass spectrometry;

[0060] The initiator ammonium persulfate accounted for 1%, and analytical grade reagents were purchased directly for use.

[0061] Preparation process

[0062] Add polyether-modified silicone and amino-terminated polyether into the reactor and stir at 250 r / min for 50 minutes at 55°C. During the stirring process, use an online viscometer to continuously monitor the viscosity of the material and record the viscosity-time curve;

[0063] Add nano-titanium dioxide-graphene composite and continue stirring for 80 minutes. Observe the distribution of the composite in the system by scanning electron microscopy and adjust the stirring parameters if necessary;

[0064] Add fatty acid polyoxyethylene ester and initiator ammonium persulfate, and react at 85°C for 3.5 hours. Use Fourier transform infrared spectrometer to track the changes of chemical bonds during the reaction and judge the progress of the reaction;

[0065] 30 minutes before the end of the reaction, the new zwitterionic surfactant was added, and the mixture was cooled to room temperature after the reaction was completed. During the cooling process, samples were taken regularly to observe the stability and appearance of the demulsifier.

[0066] Performance Testing

[0067] We selected crude oil with a water content of 15%, a salt content of 1500mg / L, and an acid value of 2mgKOH / g, added 100mg / L of demulsifier, and tested it after standing for 2.5 hours in a 45 degree Celsius environment. The results showed:

[0068] The dehydration rate was determined by centrifugation, and the dehydration rate was calculated to be 92% after centrifugation at 4000 rpm for 15 minutes. The desalination rate was determined by potentiometric titration to determine the change in salt content before and after demulsification, and the calculated desalination rate was 82%. The decomposition of organic impurities was analyzed by gas chromatography-mass spectrometry, which showed that some organic impurities were decomposed and the quality of crude oil was improved. The change in crude oil viscosity was determined using a rotational viscometer at 30 degrees Celsius, and the viscosity decreased and the fluidity improved.

[0069] Example 3

[0070] Raw material composition

[0071] Polyether-modified silicone accounts for 42%, with a relative molecular mass of 2500 for the polyether segment, a degree of polymerization of 35 for the siloxane segment, and pH-responsive carboxylate groups. Related parameters need to be detected by nuclear magnetic resonance hydrogen spectrum, gel permeation chromatography and Fourier transform infrared spectroscopy;

[0072] The amino-terminated polyether accounts for 28%, the amine value is 550 mg potassium hydroxide per gram, the relative molecular mass is 3500, and it contains fluoroalkyl side chains. The amine value needs to be determined by acid-base titration, the molecular weight needs to be determined by gel permeation chromatography, and the fluoroalkyl side chains need to be verified by elemental analysis;

[0073] Nano-titanium dioxide-graphene composites account for 18%, of which the nano-titanium dioxide particle size is 40 nanometers, the graphene sheet thickness is 4 nanometers and is nitrogen-doped. The composite structure needs to be observed by transmission electron microscopy, and the nitrogen doping needs to be verified by X-ray photoelectron spectroscopy;

[0074] Fatty acid polyoxyethylene esters account for 8%, the fatty acid carbon chain length is 18, the polyoxyethylene chain polymerization degree is 12 and contains unsaturated double bonds. The carbon chain length needs to be analyzed by gas chromatography-mass spectrometry, the hydroxyl value needs to be measured to calculate the polymerization degree, and the presence of double bonds needs to be confirmed by infrared spectroscopy;

[0075] New zwitterionic surfactants account for 3%, with an alkyl chain length of 11 and quaternary ammonium nitrogen atoms containing specific functional groups. The structure and purity need to be verified by nuclear magnetic resonance carbon spectroscopy and electrospray ionization mass spectrometry;

[0076] The initiator ammonium persulfate accounted for 1%, and analytical grade reagents were purchased directly for use.

[0077] Preparation process

[0078] Add polyether-modified silicone and amino-terminated polyether into the reactor and stir at 350 r / min for 35 minutes at 65°C. Use a torque sensor to monitor the torque change during stirring and evaluate the material mixing effect.

[0079] Add nano-titanium dioxide-graphene composite and continue stirring for 70 minutes. Observe the dispersion state of the composite with the aid of atomic force microscopy and optimize the stirring conditions.

[0080] Fatty acid polyoxyethylene ester and initiator ammonium persulfate were added and reacted at 95° C. for 2.5 hours. A differential scanning calorimeter was used to analyze the thermal effect during the reaction and monitor the reaction progress.

[0081] The novel zwitterionic surfactant was added 30 minutes before the end of the reaction, and the mixture was cooled to room temperature after the reaction was completed. The physical property changes of the demulsifier were monitored during cooling.

[0082] Performance Testing

[0083] For crude oil with a water content of 25%, a salt content of 2500mg / L, and an acid value of 4mgKOH / g, 150mg / L of demulsifier was added and allowed to stand at 55 degrees Celsius for 1.5 hours. The test results showed:

[0084] The dehydration rate was determined by centrifugal separation and was calculated to be 94%. The desalination rate was calculated to be 84% after analyzing the change in salt content using potentiometric titration. The decomposition of organic impurities was detected by gas chromatography-mass spectrometry, which showed that the content of organic impurities was significantly reduced and the photocatalytic decomposition effect was obvious. The change in crude oil viscosity was determined using a rotational viscometer, which showed a significant drop in viscosity, significantly improved crude oil fluidity, and easier transportation.

[0085] Comparative Example

[0086] Raw materials and preparation

[0087] Common traditional polyether demulsifiers are selected and prepared in a calibrated reactor of the same specifications according to their conventional production process. During the preparation process, the temperature, pressure, reaction time and other conditions are strictly controlled according to the traditional process parameters.

[0088] Performance Testing

[0089] The crude oil with the same properties as in Example 1 was selected, 120 mg / L of a conventional demulsifier was added, and the test was performed after standing for 2 hours at 50°C. The results showed:

[0090] The dehydration rate was determined to be 70% by centrifugal separation. The desalination rate was calculated to be 60% after analyzing the change in salt content by potentiometric titration. The decomposition of organic impurities was detected by gas chromatography-mass spectrometry, which showed that the organic impurities were almost not decomposed and the content remained basically unchanged. The change in crude oil viscosity was determined by a rotational viscometer, which showed no significant change in viscosity and the crude oil fluidity was poor.

[0091] By comparing the detailed data of each embodiment with the comparative example, it is clearly shown that the crude oil demulsifier of this patent has significant advantages over traditional demulsifiers in terms of demulsification efficiency, desalting capacity, organic impurity treatment and improvement of crude oil fluidity.

[0092] Comparison table of basic demulsification performance of examples and comparative examples:

[0093] Compare Projects Example 1 Example 2 Example 3 Comparative Example Dehydration rate (%) 93 92 94 70 Desalination rate (%) 83 82 84 60 Decomposition rate of organic impurities (%) 30 25 50 0 Viscosity reduction (%) 30 25 40 0 Demulsifier concentration (mg / L) 120 100 150 120 Processing temperature (℃) 50 45 55 50 Processing time (hours) 2 2.5 1.5 2

[0094] Conclusion: The dehydration rates of Examples 1-3 are 93%, 92%, and 94%, respectively, and the desalination rates are 83%, 82%, and 84%, which are significantly higher than 70% and 60% of the comparative examples; at the same time, the decomposition rate of organic impurities in Example 3 is as high as 50%, while the traditional demulsifier has no decomposition effect; in terms of viscosity improvement, the patented product reduces the viscosity by 25%-40%, while the comparative example has no change; although the processing temperature is similar, the demulsifier of the present invention achieves higher efficiency in a shorter time.

[0095] Comparison table of efficiency and economy of embodiments and comparative examples:

[0096]

[0097]

[0098] Conclusion: The treatment efficiency of Example 3 is 600 liters per hour, which is twice that of the comparative example, and the photocatalytic activity is 5 units, which can significantly reduce organic impurities; the demulsifier cost of Example 2 is the lowest, which is 10 US dollars per kilogram, and its economy is better than that of traditional demulsifiers; the temperature sensitivity index of all examples is 2-3, indicating that they have strong adaptability, while the comparative example requires a higher temperature and has low efficiency.

[0099] Function and stability comparison table of embodiments and comparative examples:

[0100] Compare Projects Example 1 Example 2 Example 3 Comparative Example Photocatalytic degradation ability (1 / 0) 0 0 1 0 Environmental rating (1–5) 5 5 5 2 Viscosity Improvement Index (1–5) 4 3 5 1 Operational complexity (1–5) 3 3 3 1 Storage stability (month) 12 12 12 6

[0101] Conclusion: The unique photocatalytic degradation ability of Example 3 makes it an efficient and environmentally friendly choice, and the environmental protection score is 5 points, far exceeding the 2 points of the comparative example; the storage stability of all examples is 12 months, while the comparative example is only 6 months; the viscosity improvement index is as high as 5, the operation complexity is moderate but the effect is far better than traditional demulsifiers, and it is suitable for long-term industrial applications.

[0102] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A crude oil demulsifier, characterized in that: The demulsifier is composed of polyether-modified silicone, amino-terminated polyether, nano-titanium dioxide-graphene composite, fatty acid polyoxyethylene ester, initiator ammonium persulfate and novel zwitterionic surfactant sulfonate betaine derivative; wherein the mass fraction of polyether-modified silicone is 30%-45%, the mass fraction of amino-terminated polyether is 25%-35%, the mass fraction of nano-titanium dioxide-graphene composite is 15%-25%, the mass fraction of fatty acid polyoxyethylene ester is 5%-10%, the mass fraction of initiator ammonium persulfate is 0.5%-2%, and the mass fraction of novel zwitterionic surfactant sulfonate betaine derivative is 3%-8%; the nano-titanium dioxide-graphene composite is prepared by hydrolyzing TiOCl2 to generate TiO2 nanoparticles, and simultaneously reducing graphene oxide to reduced graphene rGO by hydrazine hydrate, and finally loading TiO2 nanoparticles on the surface of rGO, and the reaction formula can be simplified as: The novel zwitterionic surfactant sulfonate betaine derivative is prepared by reacting N,N-dimethylaminopropylamine with 1,3-propane sultone under heating conditions. The chemical structural formula of the sulfonate betaine derivative is: The chemical reaction formula for its preparation is specifically:

2. The crude oil demulsifier according to claim 1, characterized in that: In the polyether-modified organic silicon, the relative molecular mass of the polyether segment is 1000-3000, the degree of polymerization of the siloxane segment is 20-50, and the end of the polyether segment is grafted with a carboxylate group having pH responsiveness.

3. The crude oil demulsifier according to claim 1, characterized in that: The amine value of the amino-terminated polyether is 400-600 mgKOH / g, the relative molecular mass is 2000-4000, and a fluorinated alkyl side chain is introduced into the amino-terminated polyether molecule.

4. The crude oil demulsifier according to claim 1, characterized in that: In the nano-titanium dioxide-graphene composite, the particle size of the nano-titanium dioxide is 10-50nm, the thickness of the graphene sheet is 1-5nm, the nano-titanium dioxide is uniformly loaded on the surface of the graphene sheet, and the graphene sheet is treated by nitrogen doping.

5. The crude oil demulsifier according to claim 1, characterized in that: In the fatty acid polyoxyethylene ester, the carbon chain length of the fatty acid is 12-18, the polymerization degree of the polyoxyethylene chain is 5-15, and the fatty acid part contains unsaturated double bonds and can participate in free radical polymerization reaction.

6. The crude oil demulsifier according to claim 1, characterized in that: In the novel zwitterionic surfactant sulfonate betaine derivative, the length of the alkyl chain in the molecular structure is 8-12, and a functional group capable of forming a complex with specific impurities in crude oil is introduced on the quaternary ammonium nitrogen atom.

7. A method for preparing a crude oil demulsifier according to any one of claims 1 to 6, characterized in that: The following steps are involved: Add polyether-modified silicone and amino-terminated polyether into a reaction kettle, stir and mix at 50-70°C for 30-60 minutes at a stirring speed of 200-400r / min; add nano-titanium dioxide-graphene composite, continue stirring for 60-90 minutes to fully mix the components; add fatty acid polyoxyethylene ester and initiator ammonium persulfate, react at 80-100°C for 2-4 hours; 30 minutes before the end of the reaction, add a novel zwitterionic surfactant sulfonic acid betaine derivative, continue the reaction until the end; after the reaction is completed, cool to room temperature to obtain the crude oil demulsifier.

8. Use of the crude oil demulsifier according to any one of claims 1 to 6 in a crude oil dehydration and desalination process, characterized in that: The crude oil demulsifier is added to the crude oil at a concentration of 50-200 mg / L and allowed to stand at 40-60° C. for 1-3 hours; for crude oil with high acid value, the pH of the crude oil can be adjusted to 6-8 before adding the demulsifier.

9. The use according to claim 8, characterized in that: The water content of the crude oil is 10%-30%, the salt content is 500-5000 mg / L, and the acid value is 1-10 mgKOH / g.

10. The use according to claim 8, characterized in that: After using the crude oil demulsifier, the dehydration rate of crude oil is not less than 90%, and the desalination rate is not less than 80%. For crude oil with a high acid value of 5-10 mgKOH / g, the dehydration rate can still reach more than 85%, and the desalination rate is not less than 75%.

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