A composite defoaming agent for delayed coking and preparation method thereof

Abstract

The invention discloses a composite defoamer for delayed coking and a preparation method thereof, and belongs to the field of defoamer processing technology. The present invention is used to solve the technical problem that the defoaming performance and foam suppression performance of defoamers in the prior art need to be further improved, a composite defoamer for delayed coking, including the following raw materials by mass: 10 15 parts of modified capsules, 30 40 parts of silicone oils, 1 3 parts of emulsifiers and 5 10 parts of thickening solutions. The present invention prepares composite defoamers by emulsion blending method by modified capsules, silicone oils, emulsifiers and thickening solutions, not only improves the defoaming performance and foam suppression performance of defoamers, but also improves its high-temperature defoaming performance and high-temperature foam suppression performance in delayed coking.

Description

Technical Field

[0001] The invention relates to the technical field of defoaming agent processing, and in particular to a delayed coking composite defoaming agent and a preparation method thereof. Background Art

[0002] Delayed coking is a heavy oil processing process with an operating temperature of over 480°C. It is often accompanied by the generation of large amounts of foam in the coking reactor. If not eliminated in a timely manner, it will lead to flooding of the coke tower, reduced heat exchange efficiency, and even abnormal operation of the equipment. To suppress foam, the industry widely uses defoamers containing polysiloxanes, mineral oils, silicone pastes or hydrophobic particles.

[0003] In recent years, composite defoamers have gradually become a research hotspot due to their dual functions of "rapid foam breaking + long-lasting foam suppression". This type of product usually uses silicone, non-silicon systems in conjunction with carrier particles or emulsified matrices. By regulating interfacial tension, inhibiting foam film stability and prolonging foam suppression time, it has initially achieved industrial application in high-temperature scenarios such as delayed coking and coal gas purification. However, there are still some problems with composite defoamers for delayed coking.

[0004] In the existing technology, under high temperature environment, conventional silicone oil or emulsion defoaming components are prone to volatilization, decomposition or failure, resulting in a sudden drop in defoaming activity. Secondly, the foam formation mechanism is complex, involving interference from multiple factors such as tar and suspended solids. Ordinary surfactants are difficult to accurately break the film or maintain long-term anti-foaming effects. In order to improve the thermal stability, anti-foaming durability and dispersion stability of the defoaming agent, nanoparticles are often added as reinforcing materials. However, nanomaterials have poor dispersibility in defoaming agents and are easy to agglomerate, making it difficult to play a role in enhancing the defoaming performance. Summary of the Invention

[0005] The object of the present invention is to provide a composite defoamer for delayed coking and a preparation method thereof, so as to solve the technical problem that the defoaming performance and foam suppression performance of the defoamer in the prior art need to be further improved.

[0006] The object of the present invention can be achieved by the following technical solution: A composite defoamer for delayed coking, comprising the following raw materials in parts by mass: 10-15 parts of modified capsules, 30-40 parts of silicone oil, 1-3 parts of emulsifier and 5-10 parts of thickening liquid;

[0007] The modified capsule is prepared by the following steps:

[0008] A1. Place modified polysiloxane and modified silicone paste in a reaction kettle, heat to 40-50°C, and stir for 15-20 minutes to obtain a mixed oil phase;

[0009] A2. Place chitosan and deionized water in a reactor, add acetic acid solution to adjust the pH to 4±0.5, add the mixed oil phase, ultrasonically emulsify for 1-5 minutes, add sodium tripolyphosphate solution, stir for 5-10 minutes, and post-treat to obtain modified capsules.

[0010] The preparation reaction principle of the modified capsule is:

[0011] During the reaction, the modified polysiloxane and modified silicone paste form a uniform mixed oil phase at 40-50°C. At pH = 4 ± 0.5, the amino groups in the chitosan molecule are protonated to form , add the mixed oil phase to form small water-in-oil droplets. Chitosan is positively charged and evenly distributed on the surface of the oil droplets. Sodium tripolyphosphate is a polyanionic crosslinker that can undergo electrostatic complexation with protonated chitosan to form a capsule shell layer, which is solidified to obtain modified capsules.

[0012] The modified polysiloxane is prepared by the following steps:

[0013] B1. Place polyethylene glycol, acrylic acid, p-toluenesulfonic acid and catechol in a reactor protected by a nitrogen atmosphere, heat to 140-160° C., keep the temperature for reaction for 2-4 hours, and post-treat to obtain a modified polyether ester;

[0014] The preparation reaction formula of modified polyether ester is:

[0015]

[0016] The preparation reaction principle of modified polyether ester is:

[0017] During the reaction, under the action of p-toluenesulfonic acid and high temperature, polyethylene glycol and acrylic acid undergo esterification reaction to obtain modified polyether ester, wherein catechol is an inhibitor to prevent the self-polymerization of acrylic acid during the reaction.

[0018] B2. Place the modified polyether ester, fluorinated polysiloxane and platinum dichloride in a reaction kettle, heat to 140-160° C., keep the temperature for reaction for 4-6 hours, and post-treat to obtain the modified polysiloxane.

[0019] The preparation reaction formula of modified polysiloxane is:

[0020]

[0021] Where: ;

[0022] .

[0023] The preparation reaction principle of modified polysiloxane is:

[0024] During the reaction, under the catalysis of platinum dichloride, the unsaturated double bond of olefin in the modified polyether ester and the silicon hydrogen of the fluorinated polysiloxane undergo addition reaction to obtain the modified polysiloxane.

[0025] Furthermore, in step A1, the amount ratio of the modified polysiloxane and the modified silicone paste is 1-2g:20-30g; in step A2, the amount ratio of the chitosan, deionized water, mixed oil phase and sodium tripolyphosphate solution is 0.5-1g:1000-1500mL:35-40mL:3-5mL, the acetic acid solution is composed of a 1-5wt% acetic acid aqueous solution, and the sodium tripolyphosphate solution is composed of a 30-50wt% sodium tripolyphosphate aqueous solution. The post-treatment step includes: after the reaction is completed, the reaction liquid is cooled to room temperature, filtered, the filter cake is washed with deionized water 2-3 times, transferred to an oven at a temperature of 60-70°C, and dried to constant weight to obtain modified capsules.

[0026] Furthermore, in step B1, the amount ratio of the polyethylene glycol, acrylic acid, p-toluenesulfonic acid and catechol is 2-4g:1-3g:0.1-0.3g:0.01-0.02g, and the post-treatment step includes: after the reaction is completed, the reaction solution is cooled to room temperature, sodium bicarbonate is slowly added to the reaction solution until the reaction solution no longer emits bubbles, filtered, and the filtrate is transferred to a rotary evaporator at a temperature of 50-70°C, and rotated until no liquid is extracted to obtain a modified polyether ester; in step B2, the amount ratio of the modified polyether ester, fluorinated polysiloxane and hydroxyisopropylbenzene peroxide is 2-4g:2-4g:0.1-0.3g, and the post-treatment step includes: after the reaction is completed, the reaction solution is cooled to room temperature, filtered, and the filtrate is transferred to a rotary evaporator at a temperature of 60-70°C, and rotated until no liquid is extracted to obtain a modified polysiloxane.

[0027] Furthermore, the preparation method of the fluorinated polysiloxane is as follows: toluene, octamethylcyclotetrasiloxane, 2,4,6,8-tetramethylcyclotetrasiloxane, 1,1,3,3-tetramethyldisiloxane and 1,3,5-trimethyl-1,3,5-tris(3,3,3-trifluoropropyl)cyclotrisiloxane are placed in a reactor protected by a nitrogen atmosphere, the temperature is raised to 30-40°C, a catalyst is added, the reaction is kept warm for 20-24 hours, and post-processing is performed to obtain the fluorinated polysiloxane.

[0028] The preparation reaction formula of fluorinated polysiloxane is:

[0029]

[0030] The preparation reaction principle of fluorinated polysiloxane is:

[0031] During the reaction, octamethylcyclotetrasiloxane, 2,4,6,8-tetramethylcyclotetrasiloxane and 1,3,5-trimethyl-1,3,5-tris(3,3,3-trifluoropropyl)cyclotrisiloxane are ring-opening polymerized under the action of a catalyst to obtain a block polysiloxane, which is then terminated with 1,1,3,3-tetramethyldisiloxane to obtain a fluorinated polysiloxane.

[0032] Furthermore, the amount ratio of toluene, octamethylcyclotetrasiloxane, 2,4,6,8-tetramethylcyclotetrasiloxane, 1,1,3,3-tetramethyldisiloxane, 1,3,5-trimethyl-1,3,5-tris(3,3,3-trifluoropropyl)cyclotrisiloxane and catalyst is 300-350 mL: 5-7 g: 30-35 g: 1-2 g: 2-4 g: 0.1-0.2 g, the catalyst is trifluoromethanesulfonic acid, and the post-treatment step includes: after the reaction is completed, waiting for the reaction liquid to cool to room temperature, adding 0.5-1 g of anhydrous sodium bicarbonate and 5-10 g of anhydrous sodium sulfate, stirring for 3-5 minutes, filtering, and transferring the filtrate to a rotary evaporator at a temperature of 80-90° C. and rotating until no liquid is recovered to obtain fluorinated polysiloxane.

[0033] Furthermore, the modified silicone paste is prepared by the following method:

[0034] C1. Place silica and n-octanol in a reactor, heat to 25-35°C, keep stirring for 25-35 minutes, heat to 100-110°C, keep reacting for 2-3 hours, and post-treat to obtain modified silica;

[0035] The preparation reaction principle of modified silica is:

[0036] During the reaction, under high temperature conditions, the silanol on the surface of silica undergoes a condensation reaction with n-octanol to form a silyl ether bond to obtain modified silica.

[0037] C2. Place modified silica and dimethyl silicone oil in a reactor, heat to 160-190°C, keep the temperature for reaction for 0.5-1h, and post-treat to obtain modified silicone paste.

[0038] The preparation reaction principle of modified silicone paste is:

[0039] During the reaction, the viscosity of dimethyl silicone oil decreases at high temperatures of 160-190°C, forming a close coating adsorption layer on the surface of silica, forming a gel-like modified silicone paste similar to "oil-in-solid".

[0040] Furthermore, in step C1, the amount ratio of the silica and n-octanol is 1-2g:25-35g, and the post-processing step includes: after the reaction is completed, the reaction temperature is cooled to room temperature, filtered, the filter cake is washed with deionized water 2-3 times, transferred to an oven at a temperature of 50-60°C, and dried to constant weight to obtain modified silica; in step C2, the amount ratio of the modified silica and dimethyl silicone oil is 1-2g:10-15g, and the post-processing step includes: after the reaction is completed, standing for 0.5-1h, removing the upper liquid, sealing, and obtaining a modified silicone paste.

[0041] The present invention also provides a method for preparing a composite defoamer for delayed coking, comprising the following steps:

[0042] S1. Place the thickening liquid in a reactor, heat it to 65-75°C, and stir for 10-15 minutes to obtain a mixed aqueous phase;

[0043] S2. Place silicone oil, modified capsules and emulsifier in a reactor, heat to 40-50°C, keep warm and stir for 15-20 minutes, slowly add the mixed aqueous phase, and let it stand for 10-12 hours to obtain a composite defoaming agent.

[0044] Furthermore, in step S1, the thickening liquid is composed of sodium carboxymethyl cellulose and deionized water in a mass ratio of 1:10; in step S2, the emulsifier is composed of Tween-60 and Span-60 in a mass ratio of 1:1.

[0045] The present invention has the following beneficial effects:

[0046] 1. The present invention prepares fluorinated polysiloxane by telomerization, further reacts the fluorinated polysiloxane with modified polyether ester by hydrosilylation to obtain modified polysiloxane, modifies white carbon black with long-chain alkyl groups, and prepares modified silicone paste with dimethyl silicone oil, encapsulates the modified polysiloxane and modified silicone paste with chitosan and sodium tripolyphosphate to obtain modified capsules, and prepares a composite defoamer by emulsion blending the silicone oil, modified capsules, emulsifier, and thickening liquid; the present invention prepares fluorinated polysiloxane with fluorinated silicon segments by telomerization, and during the defoaming process, the fluorinated silicon segments easily migrate to the foam interface, have extremely low surface tension, and can quickly destroy the stability of the foam film. At the same time, the modified polyetherester chain segment can improve the dispersibility and wettability of the composite defoamer in water and oil systems, accelerate its expansion to the bubble film surface, significantly shorten the natural bursting time of the foam, and increase the defoaming rate of the composite defoamer. The fluorosilicone chain segment in the modified polysiloxane contains carbon-fluorine bonds with higher bond energy, which can improve the high-temperature resistance of the composite defoamer, making its structure less prone to thermal decomposition, oxidation or chain breakage during the coking process, thereby ensuring long-term defoaming activity. At the same time, the grafted polyetherester segment in the modified polysiloxane forms a spatial three-dimensional barrier structure, forming a protective layer at the interface to inhibit the formation of new bubbles. When used in combination with the modified silicone paste, it has a good synergistic and stable release effect.

[0047] 2. The present invention modifies silica with long-chain n-octanol and further compounds it with dimethyl silicone oil to obtain a modified silicone paste. The surface of silica is rich in silanol groups, which makes it easy to absorb moisture, agglomerate, and not easily dispersed in the oil phase in the defoamer. After modification with n-octanol, the silanols on the surface of silica are reduced, which improves the dispersibility of the modified silicone paste in the defoamer, allowing it to quickly enter the foam film layer, destroy the stable structure of the liquid film, and improve the defoaming and anti-foaming properties of the composite defoamer. In addition, the silica skeleton has good thermal stability and the dimethyl silicone oil has strong heat resistance, so that the composite defoamer remains active during the delayed coking stage.

[0048] 3. The present invention utilizes chitosan and sodium tripolyphosphate to cross-link to form a shell layer, and encapsulates modified polysiloxane and modified silicone paste to obtain modified capsules. The modified silicone paste itself has excellent interfacial activity and permeability. After being wrapped in the capsule formed by chitosan-sodium tripolyphosphate cross-linking, it can be quickly broken and released instantaneously under foam interface contact, realizing "burst release-membrane rupture" type high-efficiency defoaming. Dimethyl silicone oil and hydrophobic silica have high thermal stability, and the capsule structure of the modified capsule further delays their high-temperature inactivation, thereby enhancing the duration of the composite defoamer under high-temperature conditions of delayed coking. In addition, the undamaged capsules can sustain sustained release, and the released silicone paste and modified polysiloxane can form an interface barrier and cooperate with silica to construct a physical anti-foaming layer to achieve long-term foam suppression. DETAILED DESCRIPTION

[0049] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0050] The Tween-60 used in the present invention is purchased from Hai'an Petrochemical Plant in Jiangsu Province. The product name is polyoxyethylene sorbitan stearate and the model is emulsifier Tween series T-60.

[0051] The Span-60 used in the present invention is purchased from Hai'an Petrochemical Plant in Jiangsu Province. The product name is sorbitan stearate and the model is S-60.

[0052] The white carbon black used in the present invention is purchased from the Kaiqi Mineral Products Processing Plant in Lingshou County, with a brand name of Kaiqi and a content of 98%.

[0053] The dimethyl silicone oil used in the present invention is purchased from Shandong Chuangli New Materials Co., Ltd. The product name is dimethyl silicone oil, the brand is Chuangli, and the product grade is premium grade;

[0054] The polyethylene glycol used in the present invention was purchased from Shanghai Kaisheng New Materials Co., Ltd., with a molecular weight of 600, a brand of Saudi Sabic, and a product name of polyethylene glycol 600;

[0055] The silicone oil used in the present invention is purchased from Shandong Qimin Chemical Technology Co., Ltd. The product name is methyl silicone oil and the molecular weight is 300-1000.

[0056] Example 1

[0057] This embodiment provides a method for preparing a modified polysiloxane for use in a modified capsule for a delayed coking composite defoamer, comprising the following steps:

[0058] Step I: Preparation of fluorinated polysiloxane

[0059] Weigh: 3000 mL of toluene, 50 g of octamethylcyclotetrasiloxane, 300 g of 2,4,6,8-tetramethylcyclotetrasiloxane, 10 g of 1,1,3,3-tetramethyldisiloxane and 20 g of 1,3,5-trimethyl-1,3,5-tris(3,3,3-trifluoropropyl)cyclotrisiloxane, place in a reactor protected by a nitrogen atmosphere, heat to 30 ° C, add 1 g of trifluoromethanesulfonic acid, and keep warm for 20 hours. After the reaction is completed, the reaction solution is cooled to room temperature, 5 g of anhydrous sodium bicarbonate and 50 g of anhydrous sodium sulfate are added and stirred for 3 minutes, filtered, and the filtrate is transferred to a rotary evaporator at a temperature of 80 ° C and rotated until no liquid is recovered to obtain fluorinated polysiloxane.

[0060] Step II: Preparation of modified polyether ester

[0061] Weigh: 20g of polyethylene glycol, 10g of acrylic acid, 1g of p-toluenesulfonic acid and 0.1g of catechol, place them in a reactor protected by a nitrogen atmosphere, heat to 140°C, and keep warm for 2h. After the reaction is completed, wait for the reaction liquid to cool to room temperature, slowly add sodium bicarbonate to the reaction liquid until the reaction liquid no longer emits bubbles, filter, and transfer the filtrate to a rotary evaporator at a temperature of 50°C, and rotate until no liquid is recovered to obtain a modified polyether ester.

[0062] Step III: Preparation of modified polysiloxane

[0063] Weigh: 20g of modified polyether ester, 20g of fluorinated polysiloxane and 1g of platinum dichloride are placed in a reaction kettle, heated to 140°C, and kept warm for 4 hours. After the reaction is completed, the reaction liquid is cooled to room temperature, filtered, and the filtrate is transferred to a rotary evaporator at a temperature of 60°C and rotated until no liquid is recovered to obtain modified polysiloxane.

[0064] Example 2

[0065] This embodiment provides a method for preparing a modified polysiloxane for use in a modified capsule for a delayed coking composite defoamer, comprising the following steps:

[0066] Step I: Preparation of fluorinated polysiloxane

[0067] Weigh: 3250 mL of toluene, 60 g of octamethylcyclotetrasiloxane, 325 g of 2,4,6,8-tetramethylcyclotetrasiloxane, 15 g of 1,1,3,3-tetramethyldisiloxane and 30 g of 1,3,5-trimethyl-1,3,5-tris(3,3,3-trifluoropropyl)cyclotrisiloxane, place in a reactor protected by a nitrogen atmosphere, heat to 35 ° C, add 1.5 g of trifluoromethanesulfonic acid, and keep warm for 22 hours. After the reaction is completed, wait for the reaction solution to cool to room temperature, add 7 g of anhydrous sodium bicarbonate and 70 g of anhydrous sodium sulfate, stir for 4 minutes, filter, and transfer the filtrate to a rotary evaporator at a temperature of 85 ° C. and rotate until no liquid is recovered to obtain fluorinated polysiloxane.

[0068] Step II: Preparation of modified polyether ester

[0069] Weigh: 30 g of polyethylene glycol, 15 g of acrylic acid, 2 g of p-toluenesulfonic acid and 0.15 g of catechol, place them in a reactor protected by a nitrogen atmosphere, heat to 150 ° C, and keep warm for 3 hours. After the reaction is completed, wait for the reaction liquid to cool to room temperature, slowly add sodium bicarbonate to the reaction liquid until the reaction liquid no longer emits bubbles, filter, and transfer the filtrate to a rotary evaporator at a temperature of 60 ° C, and rotate until no liquid is recovered to obtain a modified polyether ester.

[0070] Step III: Preparation of modified polysiloxane

[0071] Weigh: 30 g of modified polyether ester, 30 g of fluorinated polysiloxane and 1.5 g of platinum dichloride, place them in a reactor, heat to 150 ° C, and keep warm for 5 hours. After the reaction is completed, the reaction liquid is cooled to room temperature, filtered, and the filtrate is transferred to a rotary evaporator at a temperature of 65 ° C and rotated until no liquid is recovered to obtain modified polysiloxane.

[0072] Example 3

[0073] This embodiment provides a method for preparing a modified polysiloxane for use in a modified capsule for a delayed coking composite defoamer, comprising the following steps:

[0074] Step I: Preparation of fluorinated polysiloxane

[0075] Weigh: 3500mL of toluene, 70g of octamethylcyclotetrasiloxane, 350g of 2,4,6,8-tetramethylcyclotetrasiloxane, 20g of 1,1,3,3-tetramethyldisiloxane and 40g of 1,3,5-trimethyl-1,3,5-tris(3,3,3-trifluoropropyl)cyclotrisiloxane, place in a reactor protected by a nitrogen atmosphere, heat to 40°C, add 2g of trifluoromethanesulfonic acid, and keep warm for 24h. After the reaction is completed, wait for the reaction solution to cool to room temperature, add 10g of anhydrous sodium bicarbonate and 100g of anhydrous sodium sulfate, stir for 5min, filter, and transfer the filtrate to a rotary evaporator at a temperature of 90°C and rotate until no liquid is recovered to obtain fluorinated polysiloxane.

[0076] Step II: Preparation of modified polyether ester

[0077] Weigh: 40g of polyethylene glycol, 30g of acrylic acid, 3g of p-toluenesulfonic acid and 0.2g of catechol, place them in a reactor protected by a nitrogen atmosphere, heat to 160°C, and keep warm for 4h. After the reaction is completed, wait for the reaction liquid to cool to room temperature, slowly add sodium bicarbonate to the reaction liquid until the reaction liquid no longer emits bubbles, filter, and transfer the filtrate to a rotary evaporator at a temperature of 70°C, and rotate until no liquid is recovered to obtain a modified polyether ester.

[0078] Step III: Preparation of modified polysiloxane

[0079] Weigh: 40g of modified polyether ester, 40g of fluorinated polysiloxane and 3g of platinum dichloride are placed in a reactor, heated to 160°C, and kept warm for 6 hours. After the reaction is completed, the reaction liquid is cooled to room temperature, filtered, and the filtrate is transferred to a rotary evaporator at a temperature of 70°C and rotated until no liquid is recovered to obtain modified polysiloxane.

[0080] Example 4

[0081] This embodiment provides a method for preparing a modified silicone paste used in a modified capsule for a delayed coking composite defoamer, comprising the following steps:

[0082] Step (1), preparation of modified white carbon black

[0083] Weigh: 10g of white carbon black and 250g of n-octanol are placed in a reactor, heated to 25°C, stirred at this temperature for 25 minutes, heated to 100°C, and reacted at this temperature for 2 hours. After the reaction is completed, the temperature is cooled to room temperature, filtered, and the filter cake is washed twice with deionized water, transferred to an oven at a temperature of 50°C, and dried to constant weight to obtain modified white carbon black.

[0084] Step ⑵, preparing modified silicone paste

[0085] Weigh: 10g of modified silica and 100g of dimethyl silicone oil, place them in a reactor, heat to 160°C, and keep warm for 0.5h. After the reaction is completed, let it stand for 0.5h, remove the upper liquid, seal, and obtain modified silicone paste.

[0086] Example 5

[0087] This embodiment provides a method for preparing a modified silicone paste used in a modified capsule for a delayed coking composite defoamer, comprising the following steps:

[0088] Step (1), preparation of modified white carbon black

[0089] Weigh: 15g of white carbon black and 300g of n-octanol are placed in a reactor, heated to 30°C, stirred for 30 minutes, heated to 105°C, and reacted for 2.5 hours. After the reaction is completed, the temperature is cooled to room temperature, filtered, and the filter cake is washed twice with deionized water, transferred to an oven at 55°C, and dried to constant weight to obtain modified white carbon black.

[0090] Step ⑵, preparing modified silicone paste

[0091] Weigh: 15 g of modified silica and 125 g of dimethyl silicone oil, place them in a reactor, heat to 170° C., and keep warm for 1 hour. After the reaction is completed, let it stand for 1 hour, remove the upper liquid, and seal to obtain a modified silicone paste.

[0092] Example 6

[0093] This embodiment provides a method for preparing a modified silicone paste used in a modified capsule for a delayed coking composite defoamer, comprising the following steps:

[0094] Step (1), preparation of modified white carbon black

[0095] Weigh: 20g of white carbon black and 350g of n-octanol are placed in a reactor, heated to 35°C, stirred for 35 minutes, heated to 110°C, and reacted for 3 hours. After the reaction is completed, the temperature is cooled to room temperature, filtered, and the filter cake is washed three times with deionized water, transferred to an oven at 60°C, and dried to constant weight to obtain modified white carbon black.

[0096] Step ⑵, preparing modified silicone paste

[0097] Weigh: 20g of modified silica and 150g of dimethyl silicone oil, place them in a reactor, heat to 190°C, and keep warm for reaction for 1h. After the reaction is completed, let it stand for 1h, remove the upper liquid, seal, and obtain modified silicone paste.

[0098] Example 7

[0099] This embodiment provides a method for preparing a modified capsule for a delayed coking composite defoamer, comprising the following steps:

[0100] Step ①, prepare mixed oil phase

[0101] Weigh: 10 g of the modified polysiloxane prepared in Example 1 and 200 g of the modified silicone paste prepared in Example 4, place them in a reaction kettle, heat to 40° C., and stir for 15 minutes to obtain a mixed oil phase.

[0102] Step ②, preparation of modified capsules

[0103] Weigh: 5 g of chitosan and 10,000 mL of deionized water were placed in a reactor, 1 wt% acetic acid aqueous solution was added to adjust the pH to 3.9, 350 mL of the mixed oil phase was added, ultrasonic emulsification was performed for 1 min, 30 wt% sodium tripolyphosphate aqueous solution was added, and stirred for 5 min. After the reaction was completed, the reaction liquid was cooled to room temperature and filtered. The filter cake was washed twice with deionized water, transferred to an oven at 60°C, and dried to constant weight to obtain modified capsules.

[0104] Example 8

[0105] This embodiment provides a method for preparing a modified capsule for a delayed coking composite defoamer, comprising the following steps:

[0106] Step ①, prepare mixed oil phase

[0107] Weigh: 15 g of the modified polysiloxane prepared in Example 2 and 250 g of the modified silicone paste prepared in Example 5, place them in a reaction kettle, heat to 45° C., and stir at this temperature for 17 minutes to obtain a mixed oil phase.

[0108] Step ②, preparation of modified capsules

[0109] Weigh: 7 g of chitosan and 12500 mL of deionized water were placed in a reactor, 3 wt% acetic acid aqueous solution was added to adjust the pH to 4.2, 370 mL of the mixed oil phase was added, ultrasonic emulsification was performed for 3 minutes, 40 mL of a 40 wt% sodium tripolyphosphate aqueous solution was added, and stirred for 7 minutes. After the reaction was completed, the reaction liquid was cooled to room temperature and filtered. The filter cake was washed twice with deionized water, transferred to an oven at 65°C, and dried to constant weight to obtain modified capsules.

[0110] Example 9

[0111] This embodiment provides a method for preparing a modified capsule for a delayed coking composite defoamer, comprising the following steps:

[0112] Step ①, prepare mixed oil phase

[0113] Weigh 20 g of the modified polysiloxane prepared in Example 3 and 300 g of the modified silicone paste prepared in Example 6, place them in a reaction kettle, heat them to 50° C., and stir them for 20 minutes to obtain a mixed oil phase.

[0114] Step ②, preparation of modified capsules

[0115] Weigh: 10 g of chitosan and 15000 mL of deionized water were placed in a reactor, 5 wt% acetic acid aqueous solution was added to adjust the pH to 4.5, 400 mL of the mixed oil phase was added, ultrasonic emulsification was performed for 5 minutes, 50 mL of 50 wt% sodium tripolyphosphate aqueous solution was added, and stirred for 10 minutes. After the reaction was completed, the reaction liquid was cooled to room temperature and filtered. The filter cake was washed three times with deionized water, transferred to an oven at 70°C, and dried to constant weight to obtain modified capsules.

[0116] Example 10

[0117] This embodiment provides a method for preparing a composite defoaming agent for delayed coking, comprising the following steps:

[0118] Step 1: Prepare mixed aqueous phase

[0119] Mix sodium carboxymethyl cellulose and deionized water in a mass ratio of 1:10 to obtain a thickening solution for later use;

[0120] Weigh 5 parts of thickening liquid by mass and place them in a reaction kettle, heat it to 65°C, and stir it for 10 minutes to obtain a mixed aqueous phase.

[0121] Step 2: Preparation of composite defoamer

[0122] Mix Tween-60 and Span-60 in a mass ratio of 1:1 to obtain an emulsifier, and set aside;

[0123] Weigh 10 parts of the modified capsule prepared in Example 7, 30 parts of silicone oil and 1 part of emulsifier in parts by mass and place them in a reaction kettle. Heat to 40° C., keep stirring for 15 minutes, slowly add the mixed aqueous phase, and let stand for 10 hours to obtain a composite defoamer.

[0124] Example 11

[0125] This embodiment provides a method for preparing a composite defoaming agent for delayed coking, comprising the following steps:

[0126] Step 1: Prepare mixed aqueous phase

[0127] Mix sodium carboxymethyl cellulose and deionized water in a mass ratio of 1:10 to obtain a thickening solution for later use;

[0128] Weigh 7 parts of thickening liquid by mass and place them in a reaction kettle. Heat the mixture to 70° C. and stir the mixture for 13 minutes to obtain a mixed aqueous phase.

[0129] Step 2: Preparation of composite defoamer

[0130] Mix Tween-60 and Span-60 in a mass ratio of 1:1 to obtain an emulsifier, and set aside;

[0131] Weigh 13 parts of the modified capsule prepared in Example 8, 35 parts of silicone oil and 2 parts of emulsifier in parts by mass and place them in a reaction kettle. Heat to 45° C., keep stirring for 17 minutes, slowly add the mixed aqueous phase, and let stand for 11 hours to obtain a composite defoamer.

[0132] Example 12

[0133] This embodiment provides a method for preparing a composite defoaming agent for delayed coking, comprising the following steps:

[0134] Step 1: Prepare mixed aqueous phase

[0135] Mix sodium carboxymethyl cellulose and deionized water in a mass ratio of 1:10 to obtain a thickening solution for later use;

[0136] Weigh 10 parts of thickening liquid by mass and place them in a reaction kettle. Heat the mixture to 75° C. and stir for 15 minutes to obtain a mixed aqueous phase.

[0137] Step 2: Preparation of composite defoamer

[0138] Mix Tween-60 and Span-60 in a mass ratio of 1:1 to obtain an emulsifier, and set aside;

[0139] Weigh 15 parts of the modified capsule prepared in Example 8, 40 parts of silicone oil and 3 parts of emulsifier in parts by mass and place them in a reaction kettle. Heat to 50° C., keep stirring for 20 minutes, slowly add the mixed aqueous phase, and let stand for 12 hours to obtain a composite defoamer.

[0140] Comparative Example 1

[0141] The difference between this comparative example and Example 12 is that, in step ①, when preparing the mixed oil phase, an equal amount of 1,1,3,3-tetramethyldisiloxane is used instead of the modified polysiloxane.

[0142] Comparative Example 2

[0143] The difference between this comparative example and Example 12 is that, in step ①, when preparing the mixed oil phase, the addition of the modified silicone paste is omitted.

[0144] Comparative Example 3

[0145] The difference between this comparative example and Example 12 is that, in step 1, when preparing the mixed aqueous phase, the modified capsules are not added.

[0146] Performance testing:

[0147] The defoaming power of the composite defoamers prepared in Examples 10-12 and Comparative Examples 1-3 was measured with reference to the standard HG / T 4028-2008 “Organic Silicone High-Temperature Defoamers”;

[0148] The foam suppression performance of the composite defoamers prepared in Examples 10-12 and Comparative Examples 1-3 was measured with reference to the standard GB / T 26527-2024 "Silicone Defoamers". The specific data is the total volume of foam and liquid after 30 minutes of air blowing.

[0149] Paraffin oil, oleic acid, and coking residue were placed in a reactor in a mass ratio of 60:3:10. The temperature was raised to 250-300° C. Nitrogen was introduced through a glass bubble tube inserted into the bottom to simulate the high-temperature environment of delayed coking. The high-temperature defoaming ability and high-temperature foam suppression performance of the composite defoamers prepared in Examples 10-12 and Comparative Examples 1-3 were measured with reference to standards HG / T 4028-2008 "Organosilicon High-Temperature Defoamers" and GB / T 26527-2024 "Organosilicon Defoamers". Specific data are shown in Table 1.

[0150] Table 1 - Performance test data of each sample

[0151]

[0152] Data Analysis:

[0153] Comparative analysis of the data in Table 1 shows that the composite defoamer prepared by the present invention has a defoaming power of 29s, a foam suppression performance of 98mL, a high-temperature defoaming power of 37s, and a high-temperature foam suppression performance of 115mL, all of which are better than the comparative example;

[0154] Comparative analysis of the data of Comparative Example 1 and Example 12 shows that the defoaming power, foam suppression performance, high-temperature defoaming power and high-temperature foam suppression performance of Comparative Example 1 are significantly reduced, indicating that the present invention prepares a fluorinated polysiloxane having a fluorine-silicon segment through a polymerization reaction. During the defoaming process, the fluorine-silicon segment easily migrates to the foam interface, has an extremely low surface tension, and can quickly destroy the stability of the foam film. At the same time, the modified polyether-ester segment can improve the dispersibility and wettability of the composite defoamer in water and oil systems, accelerate its expansion to the foam film surface, significantly shorten the natural bursting time of the foam, and increase the defoaming rate of the composite defoamer. The fluorine-silicon segment in the modified polysiloxane contains a carbon-fluorine bond with a high bond energy, which can improve the high-temperature resistance of the composite defoamer and make its structure less susceptible to thermal decomposition, oxidation or chain scission during the coking process, thereby ensuring long-term defoaming activity. At the same time, the grafted polyether-ester segment in the modified polysiloxane forms a spatial barrier structure, forming a protective layer at the interface to inhibit the formation of new bubbles. When used in combination with the modified silicone paste, it has a good synergistic and stable release effect.

[0155] Comparative analysis of the data of Comparative Example 2 and Example 12 shows that the defoaming power, foam suppression performance, high-temperature defoaming power and high-temperature foam suppression performance of Comparative Example 2 are significantly reduced, indicating that the present invention uses long-chain n-octanol to modify white carbon black, and further compounding it with dimethyl silicone oil to obtain a modified silicone paste. The surface of the white carbon black is rich in silanol groups, which causes it to be easy to absorb moisture, agglomerate, and not easily dispersed in the oil phase in the defoamer. After modification with n-octanol, the silanols on the surface of the white carbon black are reduced, which improves the dispersibility of the modified silicone paste in the defoamer, allowing it to quickly enter the foam film layer, destroying the stable structure of the liquid film, and improving the defoaming performance and foam suppression performance of the composite defoamer. In addition, the white carbon black skeleton has good thermal stability and the dimethyl silicone oil has strong heat resistance, so that the composite defoamer remains active during the delayed coking stage.

[0156] By comparing and analyzing the data of Comparative Example 3 and Example 12, it can be found that the defoaming power, foam suppression performance, high-temperature defoaming power and high-temperature foam suppression performance of Comparative Example 3 are significantly reduced, indicating that the present invention utilizes chitosan and sodium tripolyphosphate to cross-link to form a shell layer, and encapsulates modified polysiloxane and modified silicone paste to obtain modified capsules. The modified silicone paste itself has excellent interfacial activity and permeability. After being wrapped by the capsule formed by chitosan-sodium tripolyphosphate cross-linking, it can be quickly ruptured and released instantaneously under foam interface contact, realizing "burst release-membrane rupture" type high-efficiency defoaming. Dimethyl silicone oil and hydrophobic silica have high thermal stability, and the capsule structure of the modified capsule further delays their high-temperature inactivation, thereby enhancing the duration of the composite defoamer under high-temperature conditions of delayed coking. In addition, the unbroken capsules can be sustainedly released, and the released silicone paste and modified polysiloxane can form an interface barrier and cooperate with silica to construct a physical anti-foam layer to achieve long-term foam suppression.

[0157] The preferred embodiments of the present invention disclosed above are intended only to help illustrate the present invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the present invention to specific embodiments. Obviously, many modifications and variations are possible based on the contents of this specification. These embodiments are selected and described in detail in this specification to better explain the principles and practical applications of the present invention, thereby enabling those skilled in the art to better understand and utilize the present invention. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A composite defoamer for delayed coking, characterized in that: The invention comprises the following raw materials in parts by mass: 10-15 parts of modified capsules, 30-40 parts of silicone oil, 1-3 parts of emulsifier and 5-10 parts of thickening liquid; The modified capsule is prepared by the following steps: A1. Place modified polysiloxane and modified silicone paste in a reaction kettle, heat to 40-50°C, and stir for 15-20 minutes to obtain a mixed oil phase; A2. Chitosan and deionized water were placed in a reactor, acetic acid solution was added to adjust the pH to 4±0.5, the mixed oil phase was added, ultrasonic emulsification was performed for 1-5 minutes, sodium tripolyphosphate solution was added, and stirring was performed for 5-10 minutes. After post-treatment, modified capsules were obtained; The modified polysiloxane is prepared by the following steps: B1. Place polyethylene glycol, acrylic acid, p-toluenesulfonic acid and catechol in a reactor protected by a nitrogen atmosphere, heat to 140-160° C., keep the temperature for reaction for 2-4 hours, and post-treat to obtain a modified polyether ester; B2. Place the modified polyether ester, fluorinated polysiloxane and platinum dichloride in a reaction kettle, heat to 140-160° C., keep the temperature for reaction for 4-6 hours, and post-treat to obtain the modified polysiloxane.

2. A composite defoamer for delayed coking according to claim 1, characterized in that In step A1, the amount ratio of the modified polysiloxane and the modified silicone paste is 1-2g:20-30g; in step A2, the amount ratio of the chitosan, deionized water, mixed oil phase and sodium tripolyphosphate solution is 0.5-1g:1000-1500mL:35-40mL:3-5mL, the acetic acid solution is composed of a 1-5wt% acetic acid aqueous solution, and the sodium tripolyphosphate solution is composed of a 30-50wt% sodium tripolyphosphate aqueous solution.

3. A composite defoamer for delayed coking according to claim 1, characterized in that In step B1, the polyethylene glycol, acrylic acid, p-toluenesulfonic acid and catechol are used in a ratio of 2-4 g: 1-3 g: 0.1-0.3 g: 0.01-0.02 g; in step B2, the modified polyether ester, fluorinated polysiloxane and hydroxyisopropylbenzene peroxide are used in a ratio of 2-4 g: 2-4 g: 0.1-0.3 g.

4. A composite defoamer for delayed coking according to claim 1, characterized in that The preparation method of the fluorinated polysiloxane comprises the following steps: placing toluene, octamethylcyclotetrasiloxane, 2,4,6,8-tetramethylcyclotetrasiloxane, 1,1,3,3-tetramethyldisiloxane and 1,3,5-trimethyl-1,3,5-tris(3,3,3-trifluoropropyl)cyclotrisiloxane in a reactor protected by a nitrogen atmosphere, heating the reactor to 30-40° C., adding a catalyst, maintaining the reaction temperature for 20-24 hours, and performing post-processing to obtain the fluorinated polysiloxane.

5. A composite defoamer for delayed coking according to claim 4, characterized in that, The amount ratio of toluene, octamethylcyclotetrasiloxane, 2,4,6,8-tetramethylcyclotetrasiloxane, 1,1,3,3-tetramethyldisiloxane, 1,3,5-trimethyl-1,3,5-tris(3,3,3-trifluoropropyl)cyclotrisiloxane and catalyst is 300-350 mL: 5-7 g: 30-35 g: 1-2 g: 2-4 g: 0.1-0.2 g, and the catalyst is trifluoromethanesulfonic acid.

6. A composite defoamer for delayed coking according to claim 1, characterized in that The modified silicone paste is prepared by the following method: C1. Place silica and n-octanol in a reactor, heat to 25-35°C, keep stirring for 25-35 minutes, heat to 100-110°C, keep reacting for 2-3 hours, and post-treat to obtain modified silica; C2. Place modified silica and dimethyl silicone oil in a reactor, heat to 160-190°C, keep the temperature for reaction for 0.5-1h, and post-treat to obtain modified silicone paste.

7. A composite defoamer for delayed coking according to claim 6, characterized in that In step C1, the ratio of the amount of white carbon black to n-octanol is 1-2g:25-35g; in step C2, the ratio of the amount of modified white carbon black to dimethyl silicone oil is 1-2g:10-15g.

8. The method for preparing a composite defoamer for delayed coking according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1. Place the thickening liquid in a reactor, heat it to 65-75°C, and stir for 10-15 minutes to obtain a mixed aqueous phase; S2. Place silicone oil, modified capsules and emulsifier in a reactor, heat to 40-50°C, keep warm and stir for 15-20 minutes, slowly add the mixed aqueous phase, and let it stand for 10-12 hours to obtain a composite defoaming agent.

9. The method for preparing a composite defoamer for delayed coking according to claim 8, wherein: In step S1, the thickening liquid is composed of sodium carboxymethyl cellulose and deionized water in a mass ratio of 1:10; in step S2, the emulsifier is composed of Tween-60 and Span-60 in a mass ratio of 1:1.

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