A preparation process for a siloxane-polyether copolymer modified coking defoamer
By using molecular bridge-mediated bonding and in-situ core-shell structure construction, the problem of insufficient stability and long-lasting defoaming performance of coking defoamers at high temperatures was solved, and the defoamer was able to operate efficiently and for a long time in the coking process.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- JIANGSU TAIHU CHEM
- Filing Date
- 2026-01-13
- Publication Date
- 2026-07-17
Smart Images
Figure CN121648614B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of chemical additives technology, and in particular to a preparation process for a siloxane-polyether copolymer modified coking defoamer. Background Technology
[0002] Delayed coking is a key process for the deep conversion of residual oil. The natural surfactants in the feedstock residual oil will generate a large amount of foam in the reaction tower, forming a thick foam layer and entraining coke powder, which will lead to coking in the fractionation tower, pipeline blockage and furnace tube fouling, seriously affecting the safe production and operating efficiency of the unit, and may also cause poisoning of downstream hydrogenation catalysts. Therefore, the application of high-efficiency defoamers is crucial.
[0003] Currently, commonly used defoamers in the coking industry mainly fall into three categories: silicone defoamers, which have fast defoaming speed and low surface tension, but poor foam suppression performance, and silicon elements are prone to deposition, leading to deactivation of downstream catalysts; polyether defoamers, which have strong foam suppression ability and good stability, but low foam breaking rate, making it difficult to quickly eliminate existing foam; and silicone-free defoamers, which avoid silicon contamination, but suffer from insufficient high-temperature resistance, large dosage, high cost, and slow diffusion and penetration. To balance these advantages, some solutions adopt siloxane-polyether copolymer modified systems, but they still have core defects: poor compatibility of active components, easily leading to layering and agglomeration; lack of stable microstructure design, resulting in rapid decay of defoaming and foam suppression performance at high temperatures; and inaccurate control of process parameters, leading to poor batch stability of products, failing to meet the coking process's demand for efficient, long-lasting, and low-pollution defoamers. Summary of the Invention
[0004] The purpose of this invention is to address the shortcomings of existing technologies by proposing a preparation process for a siloxane-polyether copolymer modified coking defoamer.
[0005] To achieve the above objectives, the present invention adopts the following technical solution: A preparation process for a siloxane-polyether copolymer modified coking defoamer includes the following steps: S1. Synthesis of epoxy-functionalized siloxane oligomers: Take methyltriethoxysilane and glycidyltrimethoxysilane, add an acid-alcohol composite catalyst, hydrolyze and condense at 60-80℃ for 2-4 hours, and then distill under reduced pressure at -0.08MPa and 80-90℃. This process involves the co-hydrolysis-condensation reaction of methyltriethoxysilane (MTES) and glycidyltrimethoxysilane (GPTMS) under an acid-alcohol composite catalyst, ultimately generating functionalized siloxane oligomers with epoxy groups (EFSO). The reaction consists of two core stages: hydrolysis and condensation. 1. Hydrolysis stage: Conversion of alkoxy groups to silanols: In this stage, the alkoxy groups in the alkoxysilanes (ethoxy group in MTES, methoxy group in GPTMS) are replaced by water molecules, generating hydroxyl-containing silanol products. Under the action of an acid-alcohol composite catalyst (from hydrochloric acid), the three ethoxy groups of MTES gradually react with water to convert into three silanol groups, releasing ethanol simultaneously; while the three methoxy groups of GPTMS also react with water simultaneously to convert into three silanol groups, releasing methanol. Throughout the process, H... + The presence of [something] activates alkoxy groups, accelerating their nucleophilic reaction with water, ultimately yielding two silanol intermediates: methylsilanetriol and glycidylsilanetriol. Acid-catalyzed hydrolysis mechanism: The core active species in the acid-alcohol composite catalyst is the alkoxy group in the hydrolysis reaction: First, it protonates the alkoxy group (such as the ethoxy group of MTES), making the alkoxy group positively charged, thereby enhancing the positive charge of the silicon atom and making it easier for water molecules to attack the silicon atom as nucleophiles; then, the protonated alkoxy group leaves the silicon atom in the form of an alcohol (ethanol or methanol); finally, the intermediate product is removed to form a silanol containing a silanol.
[0006] 2. Condensation stage: Conversion of silanols to siloxane oligomers: When sufficient silanol is generated in the system, dehydration condensation occurs between silanol molecules, which are linked to form oligomers by forming Si-O-Si bonds. Taking the molar ratio of MTES to GPTMS as 4:1 as an example, 4 molecules of methylsiloxane and 1 molecule of glycidylsiloxane will be gradually linked into a chain structure through dehydration between silanols. One end retains unreacted silanols, and the other end also retains silanols. The chain segment contains both methylsiloxane units and glycidylsiloxane units. The silanols have very weak acidity and nucleophilicity, which is insufficient to act as effective nucleophiles to attack the epoxy ring. The epoxy is retained, and the molecular weight of the siloxane oligomer is controlled between 500-2000 Da. Acid-catalyzed condensation mechanism: The condensation reaction is also catalyzed: the hydroxyl group of the silanol is first protonated to form an easily leaving water molecule; at this time, the oxygen atom (containing lone pair electrons) of the hydroxyl group in another silanol molecule acts as a nucleophile to attack the silicon atom of the protonated silanol; finally, the protonated hydroxyl group leaves in the form of a water molecule, and the two silicon atoms are firmly connected by bonds, gradually forming a chain-like siloxane oligomer.
[0007] The core of the entire reaction mechanism is to enhance the reactivity of silicon atoms through protonation, which not only achieves efficient hydrolysis of alkoxy groups but also ensures the directional condensation of silanols, ultimately yielding functionalized siloxane oligomers with epoxy groups (from GPTMS). S2. Preparation of modified siloxane-polyether copolymer matrix: Take S1 product, hydroxyl-terminated polyoxyethylene-polyoxypropylene block polyether and base silicone oil, add composite acid catalyst and toluene, react at 80-100℃ under DCS control until the amount of water separated reaches more than 95% of the theoretical value, and remove toluene at -0.08MPa and 90-100℃. H provided by composite acid catalyst + It preferentially attacks the epoxy atom in the siloxane oligomer molecule, protonating the originally electrically neutral epoxy ring (making it positively charged). This process amplifies the stress on the epoxy ring and significantly increases its reactivity. At this point, the alcohol hydroxyl group (-OH) in the terminal hydroxyl polyether molecule acts as a nucleophile and attacks one of the carbon atoms in the protonated epoxy ring, causing the epoxy ring to open. Finally, the intermediate product is removed, forming a stable ether bond (COC), which allows the polyether segment to be firmly connected to the siloxane oligomer molecule.
[0008] Meanwhile, the structure of siloxane oligomers retains silanol groups (Si-OH), and the base silicone oil also has silanol groups at both ends, and the H in the complex acid... + These Si-OH groups will first be protonated to form easily leaving Si-OH2. + Subsequently, the oxygen atom (containing a lone pair of electrons) in another silanol group acts as a nucleophile, attacking the silicon atom that protonates the silanol group; ultimately, Si-OH2... + It leaves in the form of water molecules. The two silicon units are connected by Si-O-Si bonds. The siloxane oligomer plays the role of the core molecular bridge. Through its own two active sites, epoxy group and silanol group, it tightly connects the hydroxyl-terminated polyoxyethylene-polyoxypropylene block polyether with the base silicone oil, which solves the problem of large polarity difference and poor direct compatibility between the two. Meanwhile, the hydroxyl-terminated polyoxyethylene-polyoxypropylene block polyether will directly undergo an intermolecular dehydration reaction with the base silicone oil. Under acid catalysis, the two form ether bonds through hydroxyl dehydration, achieving a tight bond.
[0009] During the above process, the water molecules generated by the reaction will form a toluene-water azeotrope with toluene (azeotropic point of about 85℃). At a reaction temperature of 80-100℃, the azeotrope will be evaporated and enter the water separator. After the water is separated into layers, it will be removed. Continuous removal of water from the system can promote the dehydration condensation reaction towards the generated modified siloxane-polyether copolymer matrix. When the amount of water separated in the water separator reaches more than 95% of the theoretical amount of water generated, the reaction can be judged to be basically completed. S3, In-situ construction of core-shell structured functionalized silica: Add ethyl orthosilicate alcohol solution dropwise at a rate of 5-10 mL / min, keep warm for 30 min, then add ammonia water dropwise, and react at 70-80℃ for 1.5-2.5 h; Ammonia water is generated by ionization in the system and becomes the core catalytic active species in the hydrolysis reaction. First, as a nucleophile, it attacks the silicon atoms in the tetraethyl orthosilicate (TEOS) molecule. Due to the difference in electronegativity, the silicon atoms are partially positively charged and are easily accepted by nucleophilic attack. Subsequently, the intermediate product after the attack undergoes proton exchange with water molecules, gradually replacing the ethoxy group in TEOS to generate silanol (Si(OH)4). At the same time, the ethanol-modified siloxane-polyether copolymer matrix provides a hydrophobic microenvironment for the reaction, which can regulate the hydrolysis rate of TEOS and avoid the reaction being too violent, which would lead to the aggregation of SiO2 particles. The silanols generated by hydrolysis undergo two types of condensation reactions under catalysis: one is the intermolecular dehydration condensation of silanol molecules. Si-OH + HO-Si → SiO2 + H2O Another type is the de-alcoholization condensation between silanol molecules: Si-OH + RO-Si → SiO2 + ROH (R is ethyl) These two types of reactions occur simultaneously, causing silanol molecules to gradually connect and form a three-dimensional network structure, which eventually aggregates to form nanoscale SiO2 particles. During the condensation reaction, the modified siloxane-polyether copolymer matrix forms a tight bond with the newly formed SiO2 particles through intermolecular forces. The siloxane segments in the matrix molecules are hydrophobic and adsorb onto the surface of the SiO2 particles through hydrophobic interactions, while the polyether segments are hydrophilic and extend outward to form a hydration layer. At the same time, some silanol groups in the matrix molecules may further condense with the silanol groups on the surface of the SiO2 particles to form chemical bonds. This "adsorption + bonding" effect allows the matrix molecules to uniformly coat the surface of the SiO2 particles, ultimately forming a stable core-shell structure. When this core-shell structure is used as a defoamer in the coking process, it has the following applications: 1. It can maintain the uniform dispersion of nano-silica through the modified siloxane-polyether copolymer shell, avoid its agglomeration and failure, and enable it to fully contact the bubble film in the coking system to play a synergistic role. 2. The shell layer is firmly bonded to the silica core and will not detach or separate under dynamic working conditions such as high-temperature stirring and fluid scouring. Combined with the high-temperature resistance of the shell layer siloxane segments, it ensures that the defoamer maintains a stable structure and performance in the high-temperature environment of coking, without loss or failure of active ingredients. 3. The silica nuclei rapidly adsorb and destroy the bubble film, while the shell reduces the stability of the bubble film and promotes the diffusion of the defoamer. The two work together to achieve the dual effect of rapid bubble breaking and long-lasting bubble suppression. At the same time, the shell coating reduces the deposition of silica particles and the adverse effects on downstream equipment and catalysts, ensuring the stable operation of the coking unit. In the in-situ construction process, TEOS alcohol solution is first added dropwise at a rate of 5-10 mL / min and kept at this temperature for 30 min to ensure uniform dispersion of TEOS in the matrix system and avoid particle agglomeration caused by excessively high local concentrations. Subsequently, ammonia water is added dropwise and the reaction temperature is controlled at 70-80℃ to ensure efficient hydrolysis and condensation reactions and to regulate the growth rate of SiO2 particles by temperature, ensuring that the particle size is controlled within the range of 20-50 nm. The reaction time of 1.5-2.5 h ensures that the condensation reaction proceeds fully, resulting in a dense SiO2 core structure and complete matrix shell coating. S4. Mixing and Post-processing: Add high-boiling-point aromatic solvent to the S3 system until the total mass percentage is 19%, homogenize at high speed for 30-60 minutes, and automatically fill and store after passing the test. High-boiling-point aromatic solvents (boiling point 180-250℃) serve as dispersion carriers, with their core function being to adjust system viscosity and improve compatibility. On the one hand, the addition of the solvent can reduce the viscosity of the system, giving it good fluidity to meet the needs of subsequent filling and industrial use. On the other hand, the solvent has excellent compatibility with the matrix, can coat the surface of core-shell structured particles, reduce the interaction force between the core-shell structured particles, and prevent particle agglomeration, laying the foundation for long-term system stability. At the same time, the high-boiling-point characteristic ensures that it is not easily volatilized under the high-temperature conditions of the coking process, maintaining the stability of the defoamer system and avoiding abnormal concentrations of active ingredients due to solvent evaporation. The high-speed homogenization process (10,000-15,000 r / min) works through strong mechanical shear force: the high-speed rotation of the homogenizer generates turbulence and shear field, which breaks up any tiny agglomerates that may exist in the system, so that the core-shell structured particles are uniformly dispersed in the solvent at the nanoscale (core particle size 20-50 nm). The homogenization time of 30-60 min ensures that the shear force is fully transmitted, ensuring that each core-shell structured particle is fully coated by the solvent, forming a stable colloidal dispersion system. In the end, the defoamer product is uniform and transparent, avoiding the impact of uneven dispersion on the defoaming effect during use.
[0010] Preferably, the acid-alcohol composite catalyst in S1 is composed of 0.1-0.2 mol / L hydrochloric acid and anhydrous ethanol in a volume ratio of 1:10, and the amount used is 0.3% of the total mass of the raw materials. The molar ratio of methyltriethoxysilane to epioxypropyltrimethoxysilane is 4-6:1.
[0011] Preferably, the number-average molecular weight of the S2 hydroxyl-terminated polyoxyethylene-polyoxypropylene block polyether is 2000-5000 Da, and the viscosity of the base silicone oil is 100-500 mPa·s.
[0012] Preferably, the molar ratio of the S1 product, hydroxyl-terminated polyoxyethylene-polyoxypropylene block polyether, and base silicone oil in S2 is 0.05-0.15:1.05-1.15:1. The composite acid catalyst is a mixture of p-toluenesulfonic acid and phosphoric acid in a mass ratio of 2-3:1, and the amount used is 0.3-0.6% of the total mass of the raw materials. The amount of toluene used is 10-15% of the total mass of the raw materials.
[0013] Preferably, the tetraethyl orthosilicate alcohol solution in S3 is composed of tetraethyl orthosilicate and anhydrous ethanol in a volume ratio of 1:4, the amount of ammonia is 5-8% of the mass of tetraethyl orthosilicate, and the dropping rate is 2 mL / min.
[0014] Preferably, the core diameter of the product in S3 is 20-50 nm, and the shell thickness is 5-10 nm.
[0015] Preferably, the testing items in S4 include flash point, pour point, appearance, closed-cup flash point, density, freezing point, defoaming rate, silicone content, antifoaming test, automated filling dynamic weighing, and net content error of ±0.5kg.
[0016] Preferably, the key equipment used in the preparation process is configured with one in operation and one on standby, and the entire production process is controlled remotely by DCS, ensuring accurate measurement of raw materials.
[0017] Compared with the prior art, the beneficial effects of the present invention are: 1. The greatest innovation of this invention lies in the dual synergistic approach of molecular bridge-mediated bonding and in-situ core-shell structure construction, combined with the multi-level reaction mechanism of epoxy ring-opening addition, silanol condensation and sol-gel encapsulation. From both the molecular structure and microstructure levels, it simultaneously solves the core pain points of poor compatibility of siloxane polyether segments and easy aggregation of nano silica in existing coking defoamers, achieving a leapfrog improvement in the high-temperature stability and long-lasting defoaming performance of defoamers.
[0018] 2. This invention utilizes self-made epoxy-functionalized siloxane oligomers as molecular bridges, combined with acid-catalyzed directional condensation and ring-opening addition mechanisms, to solve the compatibility problems caused by the physical mixing or weak bonding of traditional siloxane polyethers. One end of the epoxy-functionalized siloxane oligomer forms a siloxane-silicon bond with the base silicone oil through siloxane segments, while the other end forms a carbon-oxygen-carbon-ether bond with the polyether hydroxyl groups through epoxy groups. This chemically bonds firmly connects the two types of segments with significantly different polarities, preventing delamination and desorption during storage and high-temperature operation, and significantly improving the structural stability of the copolymer matrix.
[0019] 3. This invention employs a preparation method involving the simultaneous coating of tetraethyl orthosilicate sol-gel with a modified siloxane polyether copolymer matrix. Combined with alkaline catalytic hydrolysis condensation and interfacial adsorption and bonding mechanisms, it addresses the problems of easy agglomeration and weak synergistic effect with the matrix in traditional physical addition of nano-silica. Tetraethyl orthosilicate generates nano-silica cores in situ within the modified siloxane polyether copolymer matrix system, which are simultaneously coated by the modified siloxane polyether copolymer matrix shell to form a core-shell structure. This ensures nanoscale dispersion of silica while achieving tight bonding with the matrix through the shell, significantly enhancing the synergistic effect of siloxane defoaming and silica bubble anchoring. Attached Figure Description
[0020] Figure 1 This is a flow chart of the production process of the defoamer produced by this invention. Detailed Implementation
[0021] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, formulation composition, process features, and performance effects of the present invention, in conjunction with preferred embodiments, is provided below.
[0022] Example 1: Preparation process of modified coking defoamer: S1. Synthesis of epoxy-functionalized siloxane oligomers: Methyltriethoxysilane and glycidyltrimethoxysilane were mixed at a molar ratio of 5:1, and an acid-alcohol composite catalyst was added at a mass of 0.3% of the total raw material. The acid-alcohol composite catalyst was composed of 0.15 mol / L hydrochloric acid and anhydrous ethanol at a volume ratio of 1:10. The mixture was stirred at 70°C for 3 hours to carry out a hydrolysis-condensation reaction. Then, the low-boiling substances were removed by vacuum distillation at -0.08 MPa and 85°C to obtain an epoxy-functionalized siloxane oligomer with a molecular weight of 1000 Da. S2. Preparation of modified siloxane-polyether copolymer matrix: The epoxy-functionalized siloxane oligomer obtained in step S1, the hydroxyl-terminated polyoxyethylene-polyoxypropylene block polyether, and the base silicone oil were added to a reactor at a molar ratio of 0.05:1.1:1. Simultaneously, a composite acid catalyst (0.45% of the total raw material mass) and toluene (12.5% of the total raw material mass) were added as a dehydrating agent. The composite acid catalyst was composed of p-toluenesulfonic acid and phosphoric acid in a mass ratio of 2.5:1. Under the control of a distributed control system, the reaction system was heated to 90°C for reaction. Water generated during the reaction was separated using a water separator. When the water separation reached more than 95% of the theoretical value, the reaction was considered to be at its endpoint. Subsequently, toluene was removed by vacuum distillation at -0.08 MPa and 95°C to obtain the modified siloxane-polyether copolymer matrix. S3, In-situ construction of core-shell structured functionalized silica: The modified siloxane-polyether copolymer matrix obtained in step S2 was cooled to 75°C and stirred. A tetraethyl orthosilicate alcohol solution, composed of tetraethyl orthosilicate and anhydrous ethanol in a volume ratio of 1:4, was added dropwise at a rate of 7 mL / min. After the addition was complete, the mixture was stirred at the same temperature for 30 min. Then, ammonia water, with a mass of 6% of the added tetraethyl orthosilicate, was slowly added dropwise at a rate of 2 mL / min. After the addition was complete, the reaction was continued at 75°C for 2 h to complete the hydrolysis and condensation of tetraethyl orthosilicate, thereby generating a core-shell structured functionalized silica composite material with silica as the core and the modified siloxane-polyether copolymer as the shell in situ. S4. Mixing and Post-processing: A high-boiling-point aromatic solvent is added to the system containing core-shell structured functionalized silica composite material obtained in step S3, so that its total mass proportion in the final defoamer product is 19%; then, a high-speed shear dispersion device is used to homogenize it for 45 minutes at room temperature and pressure to obtain a uniform and stable defoamer; after sampling and testing, it is packaged and stored through an automated filling system.
[0023] Example 2: Preparation process of modified coking defoamer: S1. Synthesis of epoxy-functionalized siloxane oligomers: Methyltriethoxysilane and glycidyltrimethoxysilane were mixed at a molar ratio of 4:1, and an acid-alcohol composite catalyst was added at a mass of 0.3% of the total raw material. The acid-alcohol composite catalyst was composed of 0.15 mol / L hydrochloric acid and anhydrous ethanol at a volume ratio of 1:10. The mixture was stirred at 70°C for 3 hours to carry out a hydrolysis-condensation reaction. Then, the low-boiling substances were removed by vacuum distillation at -0.08 MPa and 85°C to obtain an epoxy-functionalized siloxane oligomer with a molecular weight of 1000 Da. S2. Preparation of modified siloxane-polyether copolymer matrix: The epoxy-functionalized siloxane oligomer obtained in step S1, the hydroxyl-terminated polyoxyethylene-polyoxypropylene block polyether, and the base silicone oil were added to a reactor at a molar ratio of 0.1:1.1:1. Simultaneously, a composite acid catalyst (0.45% of the total raw material mass) and toluene (12.5% of the total raw material mass) were added as a dehydrating agent. The composite acid catalyst was composed of p-toluenesulfonic acid and phosphoric acid in a mass ratio of 2.5:1. Under the control of a distributed control system, the reaction system was heated to 90°C for reaction. Water generated during the reaction was separated using a water separator. When the water separation reached more than 95% of the theoretical value, the reaction endpoint was determined. Subsequently, toluene was removed by vacuum distillation at -0.08 MPa and 95°C to obtain the modified siloxane-polyether copolymer matrix. S3, In-situ construction of core-shell structured functionalized silica: The modified siloxane-polyether copolymer matrix obtained in step S2 was cooled to 75°C and stirred. A tetraethyl orthosilicate alcohol solution, composed of tetraethyl orthosilicate and anhydrous ethanol in a volume ratio of 1:4, was added dropwise at a rate of 7 mL / min. After the addition was complete, the mixture was stirred at the same temperature for 30 min. Then, ammonia water, with a mass of 6% of the added tetraethyl orthosilicate, was slowly added dropwise at a rate of 2 mL / min. After the addition was complete, the reaction was continued at 75°C for 2 h to complete the hydrolysis and condensation of tetraethyl orthosilicate, thereby generating a core-shell structured functionalized silica composite material with silica as the core and the modified siloxane-polyether copolymer as the shell in situ. S4. Mixing and Post-processing: A high-boiling-point aromatic solvent is added to the system containing core-shell structured functionalized silica composite material obtained in step S3, so that its total mass proportion in the final defoamer product is 19%; then, a high-speed shear dispersion device is used to homogenize it for 45 minutes at room temperature and pressure to obtain a uniform and stable defoamer; after sampling and testing, it is packaged and stored through an automated filling system.
[0024] Example 3: Preparation process of modified coking defoamer: S1. Synthesis of epoxy-functionalized siloxane oligomers: Methyltriethoxysilane and glycidyltrimethoxysilane were mixed at a molar ratio of 5:1, and an acid-alcohol composite catalyst was added at a mass of 0.3% of the total raw material. The acid-alcohol composite catalyst was composed of 0.15 mol / L hydrochloric acid and anhydrous ethanol at a volume ratio of 1:10. The mixture was stirred at 70°C for 3 hours to carry out a hydrolysis-condensation reaction. Then, the low-boiling substances were removed by vacuum distillation at -0.08 MPa and 85°C to obtain an epoxy-functionalized siloxane oligomer with a molecular weight of 1000 Da. S2. Preparation of modified siloxane-polyether copolymer matrix: The epoxy-functionalized siloxane oligomer obtained in step S1, the hydroxyl-terminated polyoxyethylene-polyoxypropylene block polyether, and the base silicone oil were added to a reactor at a molar ratio of 0.1:1.1:1. Simultaneously, a composite acid catalyst (0.45% of the total raw material mass) and toluene (12.5% of the total raw material mass) were added as a dehydrating agent. The composite acid catalyst was composed of p-toluenesulfonic acid and phosphoric acid in a mass ratio of 2.5:1. Under the control of a distributed control system, the reaction system was heated to 90°C for reaction. Water generated during the reaction was separated using a water separator. When the water separation reached more than 95% of the theoretical value, the reaction endpoint was determined. Subsequently, toluene was removed by vacuum distillation at -0.08 MPa and 95°C to obtain the modified siloxane-polyether copolymer matrix. S3, In-situ construction of core-shell structured functionalized silica: The modified siloxane-polyether copolymer matrix obtained in step S2 was cooled to 75°C and stirred. A tetraethyl orthosilicate alcohol solution, composed of tetraethyl orthosilicate and anhydrous ethanol in a volume ratio of 1:4, was added dropwise at a rate of 7 mL / min. After the addition was complete, the mixture was stirred at the same temperature for 30 min. Then, ammonia water, with a mass of 6% of the added tetraethyl orthosilicate, was slowly added dropwise at a rate of 2 mL / min. After the addition was complete, the reaction was continued at 75°C for 2 h to complete the hydrolysis and condensation of tetraethyl orthosilicate, thereby generating a core-shell structured functionalized silica composite material with silica as the core and the modified siloxane-polyether copolymer as the shell in situ. S4. Mixing and Post-processing: A high-boiling-point aromatic solvent is added to the system containing core-shell structured functionalized silica composite material obtained in step S3, so that its total mass proportion in the final defoamer product is 19%; then, a high-speed shear dispersion device is used to homogenize it for 45 minutes at room temperature and pressure to obtain a uniform and stable defoamer; after sampling and testing, it is packaged and stored through an automated filling system.
[0025] Comparative Example 1: Compared with Example 3, in Comparative Example 1, the molar ratio of epoxy-functionalized siloxane oligomer, hydroxyl-terminated polyoxyethylene-polyoxypropylene block polyether, and base silicone oil was 0.2:1.1:1, while other conditions remained unchanged.
[0026] Comparative Example 2: Compared with Example 3, in Comparative Example 2, the molar ratio of methyltriethoxysilane to glycidyltrimethoxysilane was 7:1, and other conditions remained unchanged.
[0027] Comparative Example 3: Compared with Example 3, Comparative Example 3 directly used hydroxyl-terminated polyoxyethylene-polyoxypropylene block polyether and base silicone oil, without the participation of the epoxy-functionalized siloxane oligomer obtained in S1, and other conditions remained unchanged.
[0028] Comparative Example 4: Compared with Example 3, in Comparative Example 4, the same mass of pre-ground, solvent-dispersed SiO2 as in Example 3 was added to the S2 product, while other conditions remained unchanged.
[0029] Comparative Example 5: Compared with Example 3, there was no SiO2 enhancement in Comparative Example 5, and other conditions remained unchanged.
[0030] Comparative Example 6: Compared with Example 3, in Comparative Example 6, hydroxyl-terminated polyoxyethylene-polyoxypropylene block polyether, base silicone oil, SiO2 (pre-ground), and high-boiling-point aromatic solvent were directly mixed according to the mass ratio of Example 3, stirred at room temperature for 2 hours, without the chemical reaction steps S1, S2, and S3, and other conditions remained unchanged.
[0031] Performance testing: 1. The closed-cup flash point, pour point, density, freezing point, and silicon content of the coking defoamers prepared in the above examples and comparative examples were determined according to the standard tests in GB / T 261-2022 "Determination of Flash Point of Petroleum Products (Pinsky-Martin Closed Cup Method)", GB / T 3535-2021 "Determination of Pour Point of Petroleum Products", GB / T 1884-2000 "Determination of Density of Crude Oil and Liquid Petroleum Products (Density Meter Method)", GB / T 510-2018 "Determination of Freezing Point of Petroleum Products", and GB / T 14849.1-2020 "Industrial Silicon Chemical Analysis Methods Part 1: Determination of Silicon Content by Gravimetric Method".
[0032] 2. High-temperature defoaming rate test: Test steps: (1) Prepare a simulated coking system: Add 1000g coking residue oil + 50g coke powder + 10g deionized water to the reactor and stir evenly; (2) Heat to 380℃ (simulated coking reaction temperature), turn on stirring (300r / min), keep the temperature constant for 30min, and record the foam height H0 at this time (blank group). (3) Add 0.5g of the defoamer to be tested (addition amount 0.05%) to the system, continue stirring and timing, and record the foam heights H1, H2, H3 and H4 at 1min, 5min, 10min and 30min respectively; (4) Perform three parallel tests and take the average value.
[0033] Calculation formula: Instantaneous defoaming rate (1 min): η1 = (H0 - H1) / H0 × 100% Long-lasting defoaming rate (30 min): η4 = (H0 - H4) / H0 × 100% 3. High-temperature foam suppression test: Test steps: (1) Configure the simulated coking system according to the above steps, heat it to 380℃, stir for 30 minutes, remove the foam, and add 0.5g of the defoamer to be tested; (2) Keep the temperature and stirring rate constant, and continuously introduce nitrogen gas (flow rate 50 mL / min, simulating coking gas production), and record the time t (suppression time) required from the start of gas introduction to the foam height reaching 5 cm. (3) If the foam height does not reach 5cm within 30 minutes, record it as t≥30min; (4) Perform three parallel tests and take the average value.
[0034] Judgment criteria: A foam suppression time of ≥20 min is considered qualified (to meet the continuous operation requirements of the coking process).
[0035] 4. Anti-foaming test: Test steps: (1) Add 10L of simulated coking system (same as defoaming rate test formula) + 5g of defoamer to be tested to the circulation system and heat to 350℃; (2) Turn on the circulation pump, adjust the flow rate to 3L / min, and continue to circulate for 60min. Record the foam volume V in the foam collector every 10min. (3) Perform three parallel tests and take the average value.
[0036] Calculation formula: Cumulative antifoaming index: Vtotal = Vtotal 10 +V 20 +V 30 +V 40 +V 50 +V 60 Judgment criteria: Total V ≤ 50mL is considered qualified, and the smaller the value, the better the anti-foaming property.
[0037] 5. High-temperature stability test: Test steps: (1) Take 100g of the defoamer to be tested, place it in a sealed container, and age it at 380℃ for 24h. (2) After aging, the defoaming rates η'1 and η'4 were measured at 1 min and 30 min according to the "high temperature defoaming rate test" procedure. (3) Compare the defoaming rates η1 and η4 before aging and calculate the performance retention rate.
[0038] Calculation formula: Defoaming performance retention rate in 1 minute: K1 = η'1 / η1 × 100% 30-minute defoaming performance retention rate: K4=η'4 / η4×100%, judgment criteria: K1≥90% and K4≥85% are qualified.
[0039] Table 1 below presents some core performance data of the modified coking defoamers prepared in the embodiments and comparative examples of the present invention, covering physical performance indicators such as closed-cup flash point, pour point, density at 20°C, and freezing point, as well as the key component indicator of silicon content: Data Analysis: Figure 1This is a flow chart of the production process for the defoamer produced by this invention. The defoamer production process includes four steps: oligomer synthesis, copolymer matrix preparation, in-situ core-shell structure construction, and post-processing. The entire process is controlled by a combination of DCS and SIS safety procedures. The DCS precisely regulates process parameters such as temperature and dripping rate, while the SIS ensures production safety. The two work together to automate the process, ensuring stable product performance and controllable production safety.
[0040] The main difference between Examples 1 and 3, and Comparative Examples 1 and 3, lies in the content of epoxy-functionalized siloxane oligomers. Compared to Example 3, which serves as the standard example, Example 1 shows certain deviations in several performance indicators, with a more significant change in a certain low-temperature-related physical property. The root cause of this change is that the ratio of siloxane oligomers used in the preparation of the modified copolymer matrix in Example 1 differed from that in the standard example. This resulted in a weakening of the bonding tightness between the polyether segments and the base silicone oil, causing the relevant properties to deviate from the equilibrium state of the standard example.
[0041] The defoamer prepared in Example 3 exhibits excellent and stable performance, which is attributed to the compatibility of its process parameters: the molar ratio of silane monomers in stage S1 is reasonable, ensuring the number of active sites in the oligomers; the proportions of each component in S2 are matched, allowing for more complete chemical bonding of different chain segments; and the in-situ core-shell structure in S3 is fully constructed, enabling the synergistic effect of functional units to be fully utilized, ultimately resulting in a product with balanced performance.
[0042] Compared to Example 3, the performance variations in Comparative Example 1 were generally smaller, with only a slight fluctuation in one physical indicator. Excessive use of epoxy-functionalized siloxane oligomers led to increased system viscosity and cost. Therefore, considering both overall performance and cost, Example 3 showed better overall performance.
[0043] Compared to Example 3, Comparative Example 3 showed significant changes in several properties, with the most notable changes being in a certain safety-related property and silicon content. This is because it omitted the epoxy-functionalized siloxane oligomer in the S1 stage, resulting in a lack of effective molecular bridging between the polyether and the base silicone oil, significantly reducing their compatibility. Furthermore, the absence of silicon supplementation from the oligomer ultimately led to several properties falling far short of the standard example.
[0044] The main difference between Examples 2, 3, and Comparative Example 2 is the molar ratio of methyltriethoxysilane to glycidyltrimethoxysilane. Compared to Example 3, the data in Example 2 show smaller fluctuations, with the most significant change being in a certain low-temperature related physical property. This is because Example 2 only adjusted the molar ratio of silane monomers in the S1 stage, and the adjustment was limited, only slightly altering the epoxy distribution density of the oligomer. This had little impact on the bonding effect between the polyether and the base silicone oil, thus resulting in a less pronounced deviation from the standard example.
[0045] Compared to Example 3, the most significant change in Comparative Example 2 is in a certain safety-related performance and silicon content. This is because it drastically adjusted the proportion of silane monomers in the S1 stage, resulting in a reduction in the number of epoxy groups in the oligomer. This weakens the bonding strength with the polyether segments and also reduces the amount of silicon introduced, leading to a significant deviation in the relevant performance under the dual influence.
[0046] Compared to Example 3, Comparative Example 4 added the same mass of pre-ground, solvent-dispersed SiO2 as in Example 3 to the S2 product. The most significant change was in the antifoaming-related properties. This is because it did not use an in-situ core-shell structure, but rather physically mixed silica. The particles were prone to agglomeration and could not form a stable interface bond with the matrix. Under dynamic conditions, it was difficult to exert a synergistic defoaming effect, which led to a significant decline in antifoaming ability.
[0047] Compared to Example 3, Comparative Example 5 lacks the SiO2 enhancement effect, and the most significant change is in the defoaming durability-related performance. This is because it omits the silica enhancement process, lacking the anchoring and tearing effect of silica on the bubble film. Relying solely on the defoaming ability of the copolymer matrix, it cannot maintain a long-term foam suppression effect, resulting in a significant decline in related performance.
[0048] Compared to Example 3, Comparative Example 6 directly mixed hydroxyl-terminated polyoxyethylene-polyoxypropylene block polyether, base silicone oil, SiO2 (pre-ground), and high-boiling-point aromatic solvent according to the mass ratio of Example 3, and stirred at room temperature for 2 hours. This conventional production method lacks the chemical reaction steps S1, S2, and S3. The data in the table show that Comparative Example 6 exhibits significant changes in multiple properties, with the most prominent changes being in safety-related properties and silicon content. This is because it employs a purely physical mixing process, lacking chemical bonding and core-shell structure construction. The components exhibit poor compatibility and uneven dispersion, preventing the active ingredients from forming a synergistic effect, ultimately resulting in overall performance far lower than the standard example.
[0049] Table 2 below shows the core defoaming performance data of the modified coking defoamers prepared in the embodiments and comparative examples of the present invention. This includes the instantaneous defoaming rate at 1 minute, reflecting immediate defoaming ability; the long-lasting defoaming rate at 30 minutes, reflecting sustained foam suppression effect; the defoaming performance retention rates at 1 minute and 30 minutes, reflecting high-temperature stability; and the foam suppression time, measuring the ability to inhibit foam regeneration. These indicators can intuitively demonstrate the differences in the impact of different preparation processes on the actual working performance of the defoamers. Data Analysis: Compared to Example 3, which serves as the standard example, several defoaming-related performance indicators of Example 1 showed a certain decline, with the changes being more pronounced in indicators reflecting persistent defoaming ability. This change stems from the fact that, in preparing the modified copolymer matrix, Example 1 used a lower amount of epoxy-functionalized siloxane oligomers than the standard example. This weakened the oligomers' role as molecular bridges connecting the polyether and the base silicone oil, resulting in a decrease in the tightness of the bond between different chain segments and ultimately a weakening of the persistent defoaming effect.
[0050] The performance of Example 3 is in a relatively balanced and excellent range, which is due to the synergistic adaptation of its process parameters: the molar ratio of silane monomers in the S1 stage is set reasonably to ensure sufficient active sites of oligomers; the ratio of oligomers, polyethers and base silicone oil in S2 is adapted so that each component can form a stable structure through chemical bonding; the in-situ core-shell structure in S3 is fully constructed, so that the synergistic effect of silica and copolymer matrix can be fully exerted, ultimately achieving efficient and long-lasting defoaming performance.
[0051] Compared with Example 3, the performance of Comparative Example 1 showed a slight increase. This is because the epoxy-functionalized siloxane oligomer can strengthen the molecular bridging effect, improve the compatibility and bonding tightness between the polyether and the base silicone oil, and increase the amount of silicon introduced, resulting in an optimized trend in multiple properties such as instant defoaming and high-temperature stability. However, the amount of epoxy-functionalized siloxane oligomer is not necessarily better the more it is used. After reaching a certain level, the performance of the defoamer will not increase with the increase of the amount used, and may even decrease, because excessive aggregation of oligomer affects the stable construction of the core-shell structure, which reduces the dispersibility and effectiveness of the defoamer. Example 3 is more cost-effective.
[0052] Compared to Example 3, Comparative Example 3 showed significant deterioration in several properties, with the most notable change being in the indicators reflecting foam regeneration suppression ability. The core reason is that Comparative Example 3 omitted the synthesis step of epoxy-functionalized siloxane oligomers. Without this molecular bridge, the polyether and the base silicone oil could not form a stable chemical bond, resulting in a significant reduction in compatibility. At the same time, it also lost the structural support provided by the oligomers, leading to a significant decline in both defoaming and foam suppression abilities.
[0053] Compared to Example 3, the performance of Example 2 showed only slight fluctuations, with a relatively significant change in a certain instantaneous defoaming-related index. This is because Example 2 adjusted the molar ratio of the two silane monomers in the S1 stage, resulting in a slight change in the epoxy group distribution density in the epoxy-functionalized siloxane oligomer. This, in turn, had a slight impact on the degree of binding between the polyether segments and the oligomer, ultimately causing a targeted slight deviation in the instantaneous defoaming performance.
[0054] Compared with Example 3, Comparative Example 2 showed a significant decline in several performance indicators, with the most notable change being in the indicators reflecting foam regeneration suppression ability. The core reason is that Comparative Example 2 significantly adjusted the molar ratio of silane monomers in the S1 stage, resulting in a reduction in the number of epoxy groups in the oligomers. This weakened its role as a molecular bridge connecting the polyether and the base silicone oil, and also reduced the amount of silicon introduced. Under these dual effects, both the defoaming and foam suppression effects declined.
[0055] Compared to Example 3, Comparative Example 4 showed the most significant changes in antifoaming-related performance indicators. This is because Comparative Example 4 did not use an in-situ core-shell structure construction method, but instead physically mixed pre-ground silica with the product. This type of silica is prone to agglomeration and cannot form a stable interface bond with the copolymer matrix. Under dynamic working conditions, it is difficult to play the role of anchoring the bubble film, and ultimately the antifoaming ability is significantly weakened.
[0056] Compared to Example 3, Comparative Example 5 showed the largest change in the indicators reflecting its sustained defoaming ability. This is because Comparative Example 5 omitted the core-shell structure construction step and lacked the silica synergist component. Relying solely on the defoaming effect of the copolymer matrix, it could not achieve long-term anchoring and suppression of the bubble film, thus leading to a significant decrease in sustained defoaming performance.
[0057] Compared to Example 3, the performance of Comparative Example 6 was significantly deteriorated in all aspects, with the changes in persistent defoaming and foam regeneration inhibition indicators being the most prominent. This is because Comparative Example 6 uses a purely physical mixing process without chemical bonding or core-shell structure construction. The components have poor compatibility and uneven dispersion, making it impossible to form a stable structure for synergistic defoaming. Ultimately, the overall performance is far below that of the standard example.
[0058] Table 3 below presents the antifoaming performance test data of the modified coking defoamers prepared in the embodiments and comparative examples of the present invention. It covers the foam volume at various time points from 10 min to 60 min under simulated coking dynamic cycle conditions, as well as the cumulative antifoaming index, which comprehensively reflects the antifoaming ability. These data can intuitively show the differences in the influence of different preparation processes on the defoamer's ability to inhibit foam regeneration under dynamic disturbance conditions: Data Analysis: Compared to Example 3, the antifoaming-related data of Example 1 all showed an increase, with the cumulative antifoaming index showing the most significant change. This change stemmed from the fact that in the S2 stage of Example 1, the amount of epoxy-functionalized siloxane oligomer was lower than that of the standard example, which weakened its molecular bridging effect, resulting in a decrease in the tightness of the bond between the polyether and the base silicone oil. Consequently, the dispersion stability of the defoamer under dynamic cyclic conditions weakened, and the foam volume at each time point increased accordingly, ultimately causing the cumulative antifoaming index to deviate from the level of the standard example.
[0059] The antifoaming data of Example 3 is in an excellent and stable range, which is the result of the synergistic effect of process parameters: the molar ratio of silane monomers in stage S1 is well matched, ensuring sufficient active sites of oligomers; in S2, the components form a stable structure through chemical bonding, which improves the dispersion compatibility of the system; the core-shell structure constructed in situ in S3 allows silica and copolymer matrix to work synergistically, which can continuously suppress foam generation in dynamic cycling. Therefore, the foam volume is small at each time point, and the cumulative antifoaming index is at a low level.
[0060] Compared with Example 3, the antifoaming data of Comparative Example 1 shows that the defoamer prepared in Comparative Example 1 has better antifoaming performance in the first 20 minutes. However, as time goes on, the cumulative antifoaming index of the two is the same at 60 minutes. The antifoaming data of Example 3 is more stable within 60 minutes with almost no fluctuation. Comparative Example 1 increased the amount of epoxy-functionalized siloxane oligomer, which enhanced its role as a molecular bridge connecting polyether and base silicone oil, improved the compatibility and bonding tightness of each component, and increased the amount of silicon element introduced, further enhancing the synergistic effect of the defoaming active sites, making the overall defoaming performance slightly better than that of Example 3.
[0061] Compared to Example 3, Comparative Example 3 showed a significant increase in antifoaming data, with the most notable change in the cumulative antifoaming index. The core reason is that Comparative Example 3 did not introduce epoxy-functionalized siloxane oligomers, resulting in a lack of "molecular bridge" connections between the polyether and the base silicone oil, leading to a significant decrease in compatibility. Furthermore, the absence of a core-shell structure resulted in the defoamer easily delaminating and failing during dynamic cycling, leading to a significant increase in foam generation at each time point and ultimately a cumulative antifoaming index far exceeding that of the standard example.
[0062] Compared to Example 3, the antifoaming data in Example 2 showed a slight increase, with the most significant change being in the cumulative antifoaming index. This is because Example 2 adjusted the molar ratio of the two silane monomers in stage S1, resulting in a slight change in the epoxy group distribution density in the epoxy-functionalized siloxane oligomer. This, in turn, slightly weakened its binding tightness with the polyether segments, leading to a slight decrease in the stable inhibition ability of the defoamer under dynamic cyclic conditions, ultimately resulting in a targeted slight shift in the antifoaming data.
[0063] Compared with Example 3, the antifoaming-related data of Comparative Example 2 showed a significant increase, with the most significant change being the cumulative antifoaming index. The core reason is that Comparative Example 2 drastically adjusted the molar ratio of silane monomers in the S1 stage, resulting in a reduction in the number of epoxy groups in the epoxy-functionalized siloxane oligomer. This weakened the epoxy groups' role as "molecular bridges" connecting the polyether and the base silicone oil, leading to decreased system compatibility and increased foam generation during dynamic cycling. Ultimately, the cumulative antifoaming index deviated from the excellent level of the standard example.
[0064] Compared to Example 3, the antifoaming data of Comparative Example 4 increased significantly, with the most notable change being the cumulative antifoaming index. This is because Comparative Example 4 did not use an in-situ core-shell structure construction method, but instead physically mixed pre-ground silica with the product. This type of silica is prone to agglomeration and cannot form a stable interfacial synergistic effect with the copolymer matrix. Under dynamic cyclic conditions, it is difficult to continuously suppress foam, and the foam volume increases at each time point, thus increasing the cumulative antifoaming index.
[0065] Compared to Example 3, Comparative Example 5 showed a significant increase in antifoaming-related data, with the most significant change being the cumulative antifoaming index. This is because Comparative Example 5 omitted the construction step of core-shell functionalized silica, lacking the synergistic component of silica. Relying solely on the copolymer matrix, it was difficult to suppress foam generation under dynamic cyclic conditions for a long period. As a result, the foam volume increased at each time point, ultimately leading to an increase in the cumulative antifoaming index.
[0066] Compared to Example 3, the antifoaming data of Comparative Example 6 increased significantly, with the most significant change being the cumulative antifoaming index. This is because Comparative Example 6 uses a purely physical mixing process without chemical bonding and core-shell structure construction. The components have poor compatibility and uneven dispersion, making it impossible to form a stable defoaming synergistic structure. Under dynamic cyclic conditions, it is prone to failure, resulting in a large amount of foam generation. Ultimately, the cumulative antifoaming index is much higher than that of the standard example.
[0067] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.
Claims
1. A preparation process for a siloxane-polyether copolymer modified coking defoamer, characterized in that, Includes the following steps: S1. Synthesis of epoxy-functionalized siloxane oligomers: Methyltriethoxysilane and glycidyltrimethoxysilane were added to an acid-alcohol composite catalyst and hydrolyzed and condensed at 60-80℃ for 2-4 hours. The mixture was then distilled under reduced pressure at -0.08MPa and 80-90℃. The acid-alcohol composite catalyst was composed of 0.1-0.2mol / L hydrochloric acid and anhydrous ethanol in a volume ratio of 1:
10. S2. Preparation of modified siloxane-polyether copolymer matrix: Take product S1, hydroxyl-terminated polyoxyethylene-polyoxypropylene block polyether, and base silicone oil, add a composite acid catalyst and toluene, and react at 80-100℃ under DCS control until the water content reaches more than 95% of the theoretical value. Remove toluene at -0.08MPa and 90-100℃. In S2, the molar ratio of product S1, hydroxyl-terminated polyoxyethylene-polyoxypropylene block polyether, and base silicone oil is 0.05-0.15:1.05-1.15:
1. The composite acid catalyst is a mixture of p-toluenesulfonic acid and phosphoric acid in a mass ratio of 2-3:
1. S3, In-situ construction of core-shell structured functionalized silica: The modified siloxane-polyether copolymer matrix obtained in step S2 was cooled to 75°C and stirred. Tetraethyl orthosilicate alcohol solution was added dropwise at a rate of 5-10 mL / min. After keeping it warm for 30 min, ammonia water was added dropwise, and the reaction was carried out at 70-80°C for 1.5-2.5 h. S4. Mixing and Post-processing: Add a high-boiling-point aromatic solvent to the S3 system, homogenize at high speed for 30-60 minutes, and automatically fill and store the system after passing the test.
2. The preparation process of the siloxane-polyether copolymer modified coking defoamer according to claim 1, characterized in that, The molar ratio of methyltriethoxysilane to glycidyltrimethoxysilane is 4-6:
1.
3. The preparation process of the siloxane-polyether copolymer modified coking defoamer according to claim 1, characterized in that, The S2 hydroxyl-terminated polyoxyethylene-polyoxypropylene block polyether has a number-average molecular weight of 2000-5000 Da, and the viscosity of the base silicone oil is 100-500 mPa·s.
4. The preparation process of the siloxane-polyether copolymer modified coking defoamer according to claim 1, characterized in that, The tetraethyl orthosilicate alcohol solution in S3 is composed of tetraethyl orthosilicate and anhydrous ethanol in a volume ratio of 1:4, and the amount of ammonia water is 5-8% of the mass of tetraethyl orthosilicate, with a drop rate of 2 mL / min.
5. The preparation process of the siloxane-polyether copolymer modified coking defoamer according to claim 1, characterized in that, The core diameter of the product in S3 is 20-50 nm, and the shell thickness is 5-10 nm.
6. The preparation process of the siloxane-polyether copolymer modified coking defoamer according to claim 1, characterized in that, The testing items in S4 include flash point, pour point, appearance, density, freezing point, defoaming rate, silicon content, antifoaming test, automated filling dynamic weighing, and net content error of ±0.5kg.
7. The preparation process of the siloxane-polyether copolymer modified coking defoamer according to claim 1, characterized in that, The key equipment used in the preparation process is configured with one in operation and one on standby, and the entire production process is controlled remotely by DCS.