Preparation method of polyether defoaming agent and application thereof

Abstract

The application discloses a preparation method of a polyether defoaming agent and application thereof, and belongs to the technical field of defoaming agents. The preparation method comprises the following steps: adding modified multi-branched polyol and a catalyst into a reaction kettle and replacing air with inert gas; increasing the temperature to 130-140 DEG C, and introducing propylene oxide and butylene oxide for aging for 60-80 min; controlling the temperature to be 120-130 DEG C, and introducing ethylene oxide for aging for 40-60 min; decreasing the temperature to 85-95 DEG C, adding molecular sieve, stirring and dehydrating, adding a capping catalyst and activating for 10-15 min, adding a silazane capping agent, increasing the temperature to 105-115 DEG C, and keeping the temperature for 3-5 h; decreasing the temperature to 85-95 DEG C, removing by-products under reduced pressure, introducing inert gas, adding a chlorosilane capping agent, increasing the temperature to 100-110 DEG C, and reacting for 3-5 h; cooling and neutralizing the pH value to 6.0-7.0, and filtering to obtain the defoaming agent. The defoaming agent has the comprehensive performance of fast defoaming, long foam inhibition, resistance to extreme conditions and no oil floating.

Description

Technical Field

[0001] This application relates to a method for preparing a polyether defoamer and its application, belonging to the field of defoamer technology. Background Technology

[0002] During crude oil extraction, gathering, transportation, and refining, the synergistic effect of formation natural gas and chemical additives (oil displacement agents, demulsifiers, corrosion inhibitors, etc.) easily generates a large amount of stable foam. This foam can lead to: ① gas lock-up in oil extraction equipment, reducing extraction efficiency; ② decreased pipeline transportation volume utilization, increasing energy consumption; ③ fluctuations in distillation tower liquid levels during refining, affecting product quality; ④ foam overflow posing safety and environmental risks.

[0003] Existing crude oil defoamers are mainly classified as follows: ① Organosilicon-based: fast defoaming rate, but poor compatibility with the oil phase, prone to oil drift, clogging of filters and pipelines, affecting subsequent crude oil processing; ② Ordinary uncapped polyether-based: good compatibility, but short foam suppression time under high temperature and high salt conditions, and insufficient stability; ③ Alkyl-capped polyether-based: better foam suppression performance than ordinary polyether, but limited temperature resistance; ④ Ordinary silicon-based capped modified polyether-based: low reactivity of capping agent, insufficient capping rate (≤85%); complex process, requiring multiple catalytic steps, and high production cost.

[0004] Therefore, in order to address the problems of poor compatibility, short foam suppression time, and insufficient stability of existing crude oil defoamers in high-temperature, high-salt, and high-viscosity systems, it is necessary to develop a silicone-based end-capped polyether defoamer for crude oil that has high end-capping efficiency, resistance to extreme working conditions, excellent compatibility, and strong synergistic effect of defoaming and foam suppression. This will achieve the technical effects of "fast defoaming, long-lasting foam suppression, resistance to extreme conditions, and no oil drift," and will have significant industrial application value. Summary of the Invention

[0005] To address the aforementioned issues, a method for preparing a polyether defoamer and its application are provided. This method uses a modified multi-branched polyol as an initiator, combined with gradient polyetherification of propylene oxide, butane oxide, and ethylene oxide, and targeted end-capping with two end-capping agents to construct a multi-branched polyether with a high end-capping rate. This ensures that the polyether defoamer has higher stability, higher crude oil compatibility, and rapid spreading and film-breaking ability, ultimately achieving "fast defoaming, long-lasting foam suppression, extreme resistance, and no oil drift".

[0006] According to the first aspect of this application, a method for preparing a polyether defoamer is provided, comprising the following steps: S1: Add the modified multibranched polyol and catalyst into the reactor, and replace the air in the reactor with inert gas; S2: Heat to 130-140℃, introduce propylene oxide and butane oxide, maintain the temperature, and mature for 60-80 minutes. S3: Control the temperature at 120-130℃, introduce ethylene oxide, maintain the temperature constant, and mature for 40-60 minutes to obtain uncapped polyether; S4: Cool to 85-95℃, add molecular sieve and stir to dehydrate, add end-capping catalyst to activate for 10-15 min, add silazane end-capping agent, slowly heat to 105-115℃, and keep the temperature for 3-5 h. S5: Cool down to 85-95℃, remove byproducts under reduced pressure, then introduce inert gas, add chlorosilane end-capping agent, slowly heat up to 100-110℃, and keep the reaction at this temperature for 3-5 hours. S6: Cool, neutralize the pH to 6.0-7.0, filter, and you have the product.

[0007] The preparation method employed in this application, compared to existing methods for preparing polyether defoamers, utilizes modified multi-branched polyols as initiators. The increased number of branches and hydroxyl groups allows for the construction of a multi-branched polyether backbone, resulting in a larger spreading area compared to conventionally low-branched polyethers. This significantly increases the contact sites between molecules and the bubble film, thereby substantially improving defoaming efficiency. The increased hydroxyl groups also enhance the controllability of subsequent grafting of hydrophilic and hydrophobic segments. The gradient polyetherification process, involving the introduction of propylene oxide and butane oxide followed by ethylene oxide, enables more targeted control over the distribution of hydrophilic and hydrophobic segments in the polyether, improves the uniformity of the branched structure, ensures a higher grafting rate, and reduces self-polymerization side reactions between small molecules such as ethylene oxide.

[0008] Molecular sieve stirring and dehydration are used to avoid hydrolysis side reactions during subsequent end-capping, which could reduce the end-capping rate. End-capping methods using silazane and chlorosilane end-capping agents are employed sequentially to perform gradient end-capping of hydroxyl groups with different steric hindrances, achieving a thorough end-capping effect. This replaces hydroxyl groups with trialkylsilane groups, thereby reducing molecular polarity and surface tension while significantly enhancing the temperature and hydrolysis resistance of the polyether defoamer, enabling it to maintain high defoaming efficiency and long-lasting foam suppression even in extreme environments. After silazane end-capping, volatile byproducts are removed, and inert gas is introduced again to further remove byproducts and prevent high-temperature oxidation and yellowing of the polyether, which is more conducive to subsequent chlorosilane end-capping and assists in the preparation of polyethers with high end-capping rates. The grafting of hydrophilic and hydrophobic segments into the polyether and the high end-capping rate of trialkylsilane groups ensure the hydrophilic-hydrophobic balance of the polyether backbone, resulting in better compatibility with crude oil during use. It is less prone to oil drift, clogging of filters and pipelines, and thus does not affect subsequent crude oil processing, better meeting practical application requirements.

[0009] Optionally, the method for preparing the modified multibranched polyol in step S1 includes the following steps: Polyol and multifunctional glycidyl ether are mixed and dispersed in an organic solvent. An alkaline catalyst is added, and nitrogen is introduced to replace the air. The mixture is stirred and heated to 100-140℃ for more than 2 hours. Then, diethylene glycolamine is added dropwise until the epoxy equivalent is 0. The mixture is kept at the temperature for more than 0.5 hours, then cooled to neutralize and filtered to obtain the final product.

[0010] In this method, a multifunctional glycidyl ether undergoes a ring-opening reaction. As the basic branched structure, a polyol is first grafted onto it, simultaneously increasing the hydroxyl groups and the degree of branching. Then, diethylene glycol amine is added dropwise to cap the remaining unopened epoxy groups. During this process, the newly generated hydroxyl groups after the ring-opening of the multifunctional glycidyl ether further attack the unopened epoxy groups on other multifunctional glycidyl ethers, achieving molecular weight growth. In practice, the reactant ratio and reaction time can be adjusted according to the operating conditions and the measured epoxy equivalent to obtain modified products with different number-average molecular weights and hydroxyl values. This modification method is simple, has mild reaction conditions, and offers high controllability of branching degree and hydroxyl value. The enrichment of a large number of hydroxyl groups and the multi-branched structure provide multiple reactive sites, increasing the structural tunability and hydrophilicity / hydrophobicity controllability of the subsequent polyether preparation.

[0011] Optionally, the organic solvent is a conventional suitable solvent, such as dimethyl sulfoxide or N,N-dimethylformamide, which has high stability and increases the compatibility and dispersibility of the reactants.

[0012] Optionally, the alkaline catalyst is one or more of potassium hydroxide, sodium hydroxide, sodium carbonate, and potassium carbonate, and the amount added is 0.5%-3% of the total mass of the multifunctional glycidyl ether.

[0013] Optionally, the molar ratio of the polyol to the polyfunctional glycidyl ether is 1:(2-5).

[0014] Optionally, the modified multibranched polyol has a number-average molecular weight of 700-2400 g / mol and a hydroxyl value of 360-800 mg KOH / g.

[0015] The modified branched polyol obtained under these reactant ratios can fully undergo ring-opening, grafting, and end-capping, making it more suitable for subsequent reactions to generate polyethers with high defoaming efficiency and strong stability. Within this molecular weight range, the polyether obtained in subsequent reactions can achieve a higher spreading area and effectively break down the film. Too low a molecular weight will result in too low a molecular weight of the polyether, leading to low defoaming efficiency; too high a molecular weight will result in an excessively large molecular weight of the polyether, decreased reaction controllability, and excessively high viscosity of the product polyether, thus causing its slow diffusion rate in crude oil. Hydroxyl groups serve as active sites for subsequent reactions; too few hydroxyl groups will prevent the formation of branched polyethers, making it difficult to further improve defoaming efficiency; too many hydroxyl groups will easily lead to excessive self-polymerization, making end-capping more difficult and increasing production costs.

[0016] Optionally, the polyol includes one or more of neopentyl glycol, 2-methyl-1,3-propanediol, 3-methyl-1,5-pentanediol, pentaerythritol, and glycerol; Optionally, the multifunctional glycidyl ether is one or more of hexanediol glycidyl ether, trimethylolpropane glycidyl ether, glycerol glycidyl ether, and pentaerythritol glycidyl ether. Optionally, the silazane end-capping agent is one or both of hexamethyldisilazane and heptamethyldisilazane; Optionally, the chlorosilane end-capping agent is one or more of trimethylchlorosilane, triethylchlorosilane, and tert-butyldimethylchlorosilane.

[0017] Optionally, the molar ratio of the silazane end-capping agent to the chlorosilane end-capping agent is (0.4:0.8)-(0.8:0.4), and the molar ratio of the total molar amount of trialkylsilyl groups in the silazane end-capping agent and the chlorosilane end-capping agent to the molar amount of hydroxyl groups in the uncapped polyether is (1.1-1.3):1.

[0018] Under this ratio limit, a milder silazane end-capping agent is first used to end-cap the hydroxyl groups with low steric hindrance, and then a more active chlorosilane end-capping agent is used to end-cap the remaining hydroxyl groups with high steric hindrance. The stepwise gradient reaction achieves targeted end-capping of hydroxyl groups, improving the overall end-capping rate while minimizing the occurrence of local hydroxyl cross-linking side reactions.

[0019] Optionally, the mass ratio of propylene oxide to butane oxide in step S2 is (4.5-5.5):1.

[0020] Optionally, the mass ratio of propylene oxide to ethylene oxide in step S2 is (2.5-3.5):1.

[0021] Under the above ratio constraints, the hydrophilicity-hydrophobicity balance of the polyether backbone is ensured, making it suitable for crude oil conditions with high salinity.

[0022] Optionally, by weight, the modified branched polyol comprises 3-10 parts, the catalyst comprises 0.05-0.1 parts, the propylene oxide comprises 60-70 parts, the butane oxide comprises 10.5-15.5 parts, the ethylene oxide comprises 20-25 parts, and the end-capping catalyst comprises 0.03-0.15 parts. This ratio is strictly defined to fit this scheme, ensuring efficient reaction and improved overall performance of the defoamer.

[0023] Optionally, the catalyst and the end-capping catalyst are one or more of potassium hydroxide, sodium hydroxide, sodium carbonate, and potassium carbonate, and are all alkaline catalysts, just like the catalysts used in the preparation of modified multibranched polyols.

[0024] Optionally, the number-average molecular weight of the uncapped polyether described in step S3 is 4000-10000 g / mol. Polyethers in this molecular weight range can combine good interfacial compatibility, dispersibility, and sufficient spreading area, enabling them to quickly break down films and defoam, and are suitable for crude oil conditions with high salinity.

[0025] Optionally, the pressure when introducing the propylene oxide and the butane oxide in step S2 is 0.3-0.4 MPa.

[0026] Optionally, the pressure when introducing the ethylene oxide in step S3 is 0.25-0.35 MPa.

[0027] The aforementioned pressure allows reactants to come into full contact, improves ring-opening polymerization efficiency, reduces self-polymerization side reactions between small molecule monomers, and balances production efficiency and economic cost.

[0028] Optionally, the molecular sieve used in step S4 is a type 4A molecular sieve, and the amount added is 0.4-0.8 parts. Type 4A molecular sieve has strong water absorption, which avoids interference from hydrolysis side reactions in the subsequent end-capping reaction and affects the end-capping rate.

[0029] According to a second aspect of this application, a polyether defoamer prepared by any of the above-described methods is provided, or the application of said polyether defoamer, wherein the polyether defoamer is suitable for crude oil extraction, gathering, transportation, and refining processes, with an adaptable temperature of 120-200℃, a salinity ≥15000mg / L, and a viscosity ≥500mPa. The crude oil system of s.

[0030] This polyether defoamer is suitable for crude oil systems with high temperature, high salinity, and high viscosity. It has strong stability, wide application range, and strong tolerance to extreme working conditions. It can effectively solve the foaming problem in the entire crude oil processing process and has high industrial application value.

[0031] Optionally, the polyether defoamer has a defoaming rate of not less than 90%, a temperature-resistant defoaming rate of not less than 86%, and a salt-resistant defoaming rate of not less than 85%; the end-capping rate of the polyether defoamer is ≥88%.

[0032] This polyether defoamer exhibits excellent overall performance, with high defoaming rates, high temperature resistance, and high salt resistance, making it suitable for the extreme conditions of high temperature and high corrosion in crude oil extraction and transportation. A capping rate of ≥88% indicates sufficient hydroxyl group capping, ensuring the stability of the defoamer under extreme conditions and enabling it to continuously defoam and suppress foam.

[0033] The beneficial effects of this application include, but are not limited to: 1. The preparation method and application of the polyether defoamer of this application, compared with conventional polyol modification treatment, adopts a polyol with more branching, larger number average molecular weight and enriched hydroxyl groups after modification as the initiator, thus having the structural basis for obtaining multi-branched polyether, which has a larger effective spreading and reaction area, and significantly improves defoaming efficiency. The control of number average molecular weight and hydroxyl value also ensures that the polyether product can take into account high compatibility, high dispersibility and high stability.

[0034] 2. The preparation method and application of the polyether defoamer of this application adopt a stepwise, multi-gradient targeted polyetherification of propylene oxide, butane oxide and ethylene oxide, which increases the controllability of the hydroxyl structure on the modified multi-branched polyol, thereby obtaining a structurally optimized polyether, laying the foundation for further performance improvement.

[0035] 3. The preparation method and application of the polyether defoamer of this application employ two end-capping agents to sequentially end-cap the polyether, using targeted gradient end-capping of hydroxyl groups with different steric hindrances on the polyether to minimize interference such as side reactions, ensure a high end-capping rate, and convert hydroxyl groups into trialkylsilyl groups, thereby improving the tolerance of the polyether defoamer in extreme environments, namely high temperature and high salt crude oil systems. Its good defoaming tolerance and compatibility enable it to be applied to the entire process of crude oil extraction, gathering, transportation, and refining.

[0036] 4. The preparation method and application of the polyether defoamer of this application have good comprehensive performance, with a defoaming rate of not less than 90%, a temperature-resistant defoaming rate of not less than 86%, a salt-resistant defoaming rate of not less than 85%, a suitable temperature of 120-200℃, a mineralization of ≥15000mg / L, and a viscosity of ≥500mPa. The crude oil system of s can meet the defoaming needs of most working conditions in this field and has high industrial application value. Attached Figure Description

[0037] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings: Figure 1 This is the Fourier transform infrared spectrum of the uncapped polyether involved in Example 2 of this application.

[0038] Figure 2 This is the Fourier transform infrared spectrum of the end-capped polyether involved in Example 2 of this application. Detailed Implementation

[0039] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0040] Unless otherwise specified, the raw materials used in the embodiments and comparative examples of this application were all purchased commercially.

[0041] Unless otherwise specified, the methods used in the embodiments and comparative examples of this application are conventional methods in the prior art.

[0042] Example 1 This embodiment relates to a method for preparing a polyether defoamer, including the following steps: S1: Add 3 parts of modified multibranched polyol and 0.05 parts of potassium hydroxide into the reactor, and replace the air in the reactor with nitrogen; S2: Heat to 130℃, adjust the pressure to 0.3MPa, introduce 60 parts of propylene oxide and 10.5 parts of butylene oxide, maintain the temperature constant, and mature for 60 minutes; S3: Control the temperature at 120℃, adjust the pressure to 0.25MPa, introduce 20 parts of ethylene oxide, maintain the temperature constant, and mature for 40 minutes to obtain uncapped polyether; S4: Cool down to 85℃, add 0.4 parts of 4A molecular sieve and stir to dehydrate, add 0.03 parts of potassium hydroxide to activate for 10 min, add hexamethyldisilazane, heat to 105℃ at a rate of 1~2℃ / min, and keep the temperature for 3 h. S5: Cool down to 85℃, remove byproducts under reduced pressure, then introduce nitrogen gas, add tert-butyldimethylchlorosilane, heat up to 100℃ at a rate of 1~2℃ / min, and keep the reaction at this temperature for 3h. S6: Cool, neutralize to pH 7.0, filter, and you have the product.

[0043] The preparation method of the modified multibranched polyol in step S1 above includes the following steps: Neopentyl glycol and hexanediol glycidyl ether were mixed and dispersed in N,N-dimethylformamide. Sodium hydroxide (0.5% of the total mass of hexanediol glycidyl ether) was added, and nitrogen gas was introduced to replace the air. The mixture was stirred and heated to 100°C for 2 hours. Then, diethylene glycolamine was added dropwise until the epoxy equivalent was 0, and the reaction was maintained at this temperature for 0.5 hours. The mixture was then cooled, neutralized, and filtered to obtain the final product. The molar ratio of neopentyl glycol to hexanediol glycidyl ether was 1:2. The number average molecular weight of the resulting modified multibranched polyol was 705 g / mol, and the hydroxyl value was 469 mg KOH / g.

[0044] In the above S4, the molar ratio of trialkylsilane to hydroxyl groups in the uncapped polyether is 0.4:1, and in the above S5, the molar ratio of trialkylsilane to hydroxyl groups in the uncapped polyether is 0.8:1.

[0045] Example 2 This embodiment relates to a method for preparing a polyether defoamer, including the following steps: S1: Add 8 parts of modified multibranched polyol and 0.08 parts of sodium hydroxide into the reactor, and replace the air in the reactor with nitrogen; S2: Heat to 135℃, adjust the pressure to 0.3MPa, introduce 65 parts of propylene oxide and 12 parts of butyl oxide, maintain the temperature constant, and mature for 70 minutes; S3: Control the temperature at 125℃, adjust the pressure to 0.30MPa, introduce 22 parts of ethylene oxide, maintain the temperature constant, and mature for 50 minutes to obtain uncapped polyether; S4: Cool down to 90℃, add 0.6 parts of 4A molecular sieve and stir to dehydrate, add 0.08 parts of potassium hydroxide to activate for 12 min, add hexamethyldisilazane, heat to 110℃ at a rate of 1~2℃ / min, and keep the temperature for 4 h. S5: Cool down to 90℃, remove byproducts under reduced pressure, then introduce nitrogen gas, add trimethylchlorosilane, heat up to 105℃ at a rate of 1~2℃ / min, and keep the reaction at this temperature for 4h. S6: Cool, neutralize to pH 7.0, filter, and you have the product.

[0046] The preparation method of the modified multibranched polyol in step S1 above includes the following steps: Pentaerythritol and trimethylolpropane glycidyl ether were dispersed in dimethyl sulfoxide, and potassium hydroxide (2% of the total mass of trimethylolpropane glycidyl ether) was added. Nitrogen gas was introduced to replace the air, and the mixture was stirred and heated to 130°C for 4 hours. Then, diethylene glycolamine was added dropwise until the epoxy equivalent was zero, and the reaction was maintained at this temperature for 1 hour. The mixture was then cooled, neutralized, and filtered to obtain the final product. The molar ratio of pentaerythritol to trimethylolpropane glycidyl ether was 1:3. The number-average molecular weight of the resulting modified multibranched polyol was 1896 g / mol, and the hydroxyl value was 669 mg KOH / g.

[0047] In S4 above, the molar ratio of trialkylsilane to hydroxyl groups in the uncapped polyether is 0.6:1, and in S5 above, the molar ratio of trialkylsilane to hydroxyl groups in the uncapped polyether is 0.6:1.

[0048] Example 3 This embodiment relates to a method for preparing a polyether defoamer, including the following steps: S1: Add 10 parts of modified multibranched polyol and 0.1 parts of potassium carbonate into the reactor, and replace the air in the reactor with nitrogen; S2: Heat to 140℃, adjust the pressure to 0.4MPa, introduce 70 parts of propylene oxide and 15.5 parts of butylene oxide, maintain the temperature constant, and mature for 80 minutes; S3: Control the temperature at 130℃, adjust the pressure to 0.35MPa, introduce 25 parts of ethylene oxide, maintain the temperature constant, and mature for 60 minutes to obtain uncapped polyether; S4: Cool to 95℃, add 0.8 parts of 4A molecular sieve and stir to dehydrate, add 0.15 parts of potassium hydroxide to activate for 15 min, add heptamethyldisilazane, heat to 115℃ at a rate of 1~2℃ / min, and keep the temperature for 5 h. S5: Cool down to 95℃, remove byproducts under reduced pressure, then introduce nitrogen gas, add triethylchlorosilane, and heat to 110℃ at a rate of 1~2℃ / min, and keep the reaction at this temperature for 5h. S6: Cool, neutralize to pH 7.0, filter, and you have the product.

[0049] The preparation method of the modified multibranched polyol in step S1 above includes the following steps: Glycerol and pentaerythritol glycidyl ether were mixed and dispersed in dimethyl sulfoxide. Potassium hydroxide (3% of the total mass of pentaerythritol glycidyl ether) was added, and nitrogen gas was introduced to replace the air. The mixture was stirred and heated to 140°C for 6 hours. Then, diethylene glycolamine was added dropwise until the epoxy equivalent was 0, and the reaction was maintained at this temperature for 1 hour. The mixture was then cooled, neutralized, and filtered to obtain the final product. The molar ratio of glycerol to pentaerythritol glycidyl ether was 1:5. The number average molecular weight of the resulting modified multibranched polyol was 2373 g / mol, and the hydroxyl value was 613 mgKOH / g.

[0050] In the above S4, the molar ratio of trialkylsilane to hydroxyl groups in the uncapped polyether is 0.8:1, and in the above S5, the molar ratio of trialkylsilane to hydroxyl groups in the uncapped polyether is 0.4:1.

[0051] Example 4 The difference between this embodiment and Embodiment 2 is that diethylene glycolamine is not added.

[0052] Example 5 The difference between this embodiment and embodiment 2 is that the molar ratio of silazane end-capping agent in S4 to chlorosilane end-capping agent in S5 is 0.3:0.8, while the total amount of the two end-capping agents remains unchanged.

[0053] Example 6 The difference between this embodiment and embodiment 2 is that the molar ratio of silazane end-capping agent in S4 to chlorosilane end-capping agent in S5 is 0.8:0.3, while the total amount of the two end-capping agents remains unchanged.

[0054] Example 7 The difference between this embodiment and Embodiment 2 is that in step S2, the mass ratio of propylene oxide to butylene oxide is 1:6, while the total amount of both remains unchanged.

[0055] Example 8 The difference between this embodiment and Embodiment 2 is that the mass ratio of propylene oxide to ethylene oxide in step S2 is 1.5:1, while the total amount of both remains unchanged.

[0056] Comparative Example 1 The difference between this comparative example and Example 2 is that the modified multibranched polyol is replaced with an equal weight of pentaerythritol.

[0057] Comparative Example 2 The difference between this comparative example and Example 2 is that propylene oxide, butane oxide, and ethylene oxide are mixed and introduced.

[0058] Comparative Example 3 The difference between this comparative example and Example 2 is that, after adding potassium hydroxide for activation in step S4, silazane end-capping agent and chlorosilane end-capping agent are added together, and the reaction is maintained at this temperature for 6-10 hours.

[0059] Comparative Example 4 The difference between this comparative example and Example 2 is that the polyether was not end-capped.

[0060] Test Example 1 The polyether defoamers prepared in the above embodiments and comparative examples were tested for end-capping rate, defoaming rate, temperature resistance defoaming rate, and salt resistance defoaming rate. The test results are shown in Table 1. Each group of experiments was conducted in parallel for 5 times. After removing the maximum and minimum values, the average value was taken. The specific test methods are as follows: End-capping rate test method: According to GB / T 7383-2007 "Determination of Hydroxyl Value of Nonionic Surfactants", the hydroxyl value of the product before and after end-capping is measured. The end-capping rate of the product is estimated based on the rate of change of hydroxyl value. The specific formula is as follows:

[0061] Defoaming rate test method: For crude oil with a viscosity greater than 500 mPa·s in a certain block of Shengli Oilfield, the defoaming rate was tested according to "Q / SHCG46—2020 Technical Requirements for Crude Oil Defoamers".

[0062] Temperature resistance defoaming rate test method: Prepare a 1% dilution solution by mixing the product of the example and the product of the comparative example. After aging the dilution solution in a closed high-pressure reactor at 180°C for 24 hours, test its defoaming rate again.

[0063] Salt resistance defoaming rate test method: Dilute the product of the example and the comparative product to 1% with mineralized water with a mineralization of 20000 mg / L, and test the defoaming rate again after standing at 25°C for 24 hours.

[0064] Table 1

[0065] As can be seen from Examples 1-3, the preparation method of this application can obtain a polyether defoamer with a capping rate of 97.7% and a defoaming rate of 98.5%. Figure 1 and Figure 2 The comparison shows that 3400-3500cm -1 The OH stretching vibration peak at the point of application was significantly weakened, indicating that most of the hydroxyl groups had been capped. This high branching and high capping rate lay the foundation for excellent defoaming efficiency and allows the material to maintain relatively stable performance even in extreme crude oil environments.

[0066] Compared to Example 2, Example 4 did not include the addition of diethylene glycolamine. The remaining epoxy groups were not converted into more stable effective hydroxyl groups. Under subsequent high-temperature conditions, intermolecular cross-linking and aggregation easily occurred, leading to increased steric hindrance of some of the original effective hydroxyl groups, making them difficult to end-cap, thus significantly reducing the end-capping rate. The reduced end-capping rate resulted in a higher surface energy of the polyether, hindering rapid spreading and defoaming. The higher hydroxyl content and lower methyl content reduced the polyether's temperature and hydrolysis resistance, making it less suitable for extreme crude oil systems.

[0067] As can be seen from Examples 5-6, the molar ratio of the two end-capping agents also has a significant impact on achieving a high end-capping rate. When the proportion of silazane is low, the low-steric hydroxyl groups are not fully end-capped before the highly active chlorosilane is added, which easily triggers cross-linking side reactions, making it unable to effectively end the high-steric hydroxyl groups, thereby reducing the overall end-capping rate. When the proportion of chlorosilane is low, the high-steric hydroxyl groups lack sufficient end-capping, making it difficult to achieve the performance required for the application.

[0068] As shown in Examples 7-8, an excessively high proportion of butane oxide leads to an excessively high proportion of hydrophobic segments in the polyether, resulting in excessive compatibility with the oil phase and an inability to spread at the oil-water interface, thus reducing its defoaming and foam-suppressing capabilities. Conversely, an excessively high proportion of ethylene oxide results in excessively high hydrophilicity of the polyether, making it prone to salting out and exhibiting poor stability in high-temperature, high-salt environments.

[0069] Comparative Example 1 shows that using pentaerythritol with low branching degree and few hydroxyl groups makes it difficult to construct polyether defoamers with high defoaming rate and stability. Comparative Example 2 did not employ gradient polyetherification, failing to form ordered polyether segments, resulting in unreliable hydrophilic-philic balance. Its compatibility, spreadability, and interfacial stability in crude oil all decreased significantly, leading to a decline in defoaming performance. Comparative Example 3 did not employ gradient end-capping; the highly reactive chlorosilane preferentially reacted, easily triggering intermolecular hydroxyl cross-linking side reactions, leading to uncontrolled aggregation and severely reducing defoaming activity and stability. Comparative Example 4 shows that the defoaming ability of un-endcapped polyether defoamers decreased significantly, and in high-temperature, high-salt environments, they had almost no practical defoaming ability.

[0070] The above description is merely an embodiment of this application, and the scope of protection of this application is not limited to these specific embodiments, but is determined by the claims of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the technical concept and principles of this application should be included within the scope of protection of this application.

Claims

1. A method for preparing a polyether defoamer, characterized in that, Includes the following steps: S1: Add the modified multibranched polyol and catalyst into the reactor, and replace the air in the reactor with inert gas; S2: Heat to 130-140℃, introduce propylene oxide and butane oxide, maintain the temperature, and mature for 60-80 minutes. S3: Control the temperature at 120-130℃, introduce ethylene oxide, maintain the temperature constant, and mature for 40-60 minutes to obtain uncapped polyether; S4: Cool to 85-95℃, add molecular sieve and stir to dehydrate, add end-capping catalyst to activate for 10-15 min, add silazane end-capping agent, slowly heat to 105-115℃, and keep the temperature for 3-5 h. S5: Cool down to 85-95℃, remove byproducts under reduced pressure, then introduce inert gas, add chlorosilane end-capping agent, slowly heat up to 100-110℃, and keep the reaction at this temperature for 3-5 hours. S6: Cool, neutralize the pH to 6.0-7.0, filter, and the product is ready; The preparation method of the modified multibranched polyol described in step S1 includes the following steps: mixing and dispersing the polyol and multifunctional glycidyl ether in an organic solvent, adding an alkaline catalyst, purging with nitrogen to replace the air, stirring and heating to 100-140℃ for more than 2 hours, then adding diethylene glycol amine dropwise until the epoxy equivalent is 0, maintaining the temperature for more than 0.5 hours, cooling and neutralizing, and filtering to obtain the product; the multifunctional glycidyl ether is one or more of hexanediol glycidyl ether, trimethylolpropane glycidyl ether, glycerol glycidyl ether, and pentaerythritol glycidyl ether.

2. The method for preparing the polyether defoamer according to claim 1, characterized in that, The modified multibranched polyol has a number average molecular weight of 700-2400 g / mol and a hydroxyl value of 360-800 mg KOH / g.

3. The method for preparing the polyether defoamer according to claim 1, characterized in that, The polyols include one or more of neopentyl glycol, 2-methyl-1,3-propanediol, 3-methyl-1,5-pentanediol, pentaerythritol, and glycerol; The silazane end-capping agent is one or both of hexamethyldisilazane and heptamethyldisilazane; The chlorosilane end-capping agent is one or more of trimethylchlorosilane, triethylchlorosilane, and tert-butyldimethylchlorosilane.

4. The method for preparing the polyether defoamer according to claim 1, characterized in that, The molar ratio of the silazane end-capping agent to the chlorosilane end-capping agent is (0.4:0.8)-(0.8:0.4), and the molar ratio of the total molar amount of trialkylsilyl groups in the silazane end-capping agent and the chlorosilane end-capping agent to the molar amount of hydroxyl groups in the uncapped polyether is (1.1-1.3):

1.

5. The method for preparing the polyether defoamer according to claim 1, characterized in that, In step S2, the mass ratio of propylene oxide to butane oxide is (4.5-5.5):1; The mass ratio of propylene oxide to ethylene oxide is (2.5-3.5):

1.

6. The method for preparing the polyether defoamer according to claim 1, characterized in that, By weight, the modified multibranched polyol is 3-10 parts, the catalyst is 0.05-0.1 parts, the propylene oxide is 60-70 parts, the butane oxide is 10.5-15.5 parts, the ethylene oxide is 20-25 parts, and the end-capping catalyst is 0.03-0.15 parts.

7. The method for preparing the polyether defoamer according to claim 1, characterized in that, The number-average molecular weight of the uncapped polyether described in step S3 is 4000-10000 g / mol.

8. The application of the polyether defoamer obtained by the preparation method according to any one of claims 1-7, characterized in that, The polyether defoamer is suitable for crude oil extraction, gathering, transportation, and refining processes, with an optimal operating temperature of 120-200℃, a salinity ≥15000mg / L, and a viscosity ≥500mPa. The crude oil system of s.

9. The application of the polyether defoamer according to claim 8, characterized in that, The polyether defoamer has a defoaming rate of not less than 90%, a temperature-resistant defoaming rate of not less than 86%, and a salt-resistant defoaming rate of not less than 85%; the end-capping rate of the polyether defoamer is ≥88%.

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