Sterilizing and anti-corrosion agent for natural gas pipeline and preparation method of sterilizing and anti-corrosion agent

Abstract

The invention discloses a sterilizing and anti-corrosion agent for a natural gas pipeline and a preparation method of the sterilizing and anti-corrosion agent. The sterilizing and anti-corrosion agent is prepared from the following components in percentage by mass: 15-25% of fluorine-containing polyether modified imidazoline quaternary ammonium salt; 8-12% of a nano titanium dioxide / graphene compound; 5-10% of a polyaspartic acid derivative; 2-5% of a fluorocarbon surfactant; 3-8% of plant essential oil microcapsules; and the balance of deionized water. Corrosive media can be blocked through the nano titanium dioxide / graphene compound, electrochemical corrosion can be inhibited and microorganisms can be killed through the fluorine-containing-polyether modified imidazoline quaternary ammonium salt, then the functions of sterilization, corrosion prevention and corrosion inhibition of natural gas pipelines are achieved, and the corrosion inhibitor is suitable for inner wall protection of natural gas long-distance pipelines, urban gas pipe networks and industrial gas pipelines.

Description

Technical Field

[0001] This invention relates to the field of natural gas pipeline protection technology, and in particular to a bactericidal and anti-corrosion agent for natural gas pipelines and its preparation method. Background Technology

[0002] Natural gas, like crude oil, is buried in underground, closed geological structures. Some are stored in the same stratum as crude oil, while others exist separately. Natural gas stored in the same stratum as crude oil is extracted along with the crude oil. Natural gas containing only single-phase gas is called a gas reservoir, and its extraction method is very similar to that of crude oil.

[0003] In natural gas, dry hydrogen sulfide and carbon dioxide do not corrode pipelines. Although purified natural gas meets transportation standards, the presence of a large amount of water vapor in the natural gas causes it to condense on the inner wall of the pipeline as the gas temperature decreases during transportation. This water vapor dissolves into hydrogen sulfide and carbon dioxide, becoming acidic and causing corrosion. Therefore, these pipelines still need anti-corrosion treatment before use; otherwise, the steel pipelines will quickly corrode and rust through during use, leading to natural gas leaks and accidents. At the same time, microbial corrosion is also an important factor in the corrosion of natural gas pipelines. However, current chemical agents for natural gas pipelines have relatively limited functions. When using multiple agents in combination, not only is the dosing process cumbersome, but the compatibility between the agents also needs to be considered. Summary of the Invention

[0004] To address at least one of the aforementioned problems, this invention provides a bactericidal and anti-corrosion agent for natural gas pipelines and a method for preparing the same.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A bactericide and antiseptic agent for natural gas pipelines, comprising the following components by weight percentage:

[0007] Fluorine-containing polyether modified imidazoline quaternary ammonium salt 15-25%;

[0008] Nano-titanium dioxide / graphene composite 8-12%;

[0009] 5-10% polyaspartic acid derivatives;

[0010] Fluorocarbon surfactants 2-5%;

[0011] Plant essential oil microcapsules 3-8%;

[0012] The rest is deionized water;

[0013] The fluorinated polyether-modified imidazoline quaternary ammonium salt is prepared by the following steps:

[0014] S1, Synthesis of imidazoline intermediate: Citric acid and triethylenetetramine in a molar ratio of 1:3.5 were used to prepare hydroxylated imidazoline intermediate by dehydration condensation;

[0015] S2, Substitution reaction to introduce halogen groups: The hydroxylated imidazoline intermediate is mixed with hydroiodic acid at a molar ratio of 1:1.2 and reacted at 30-35℃ for 3-5 hours. The intermediate is then separated and purified to obtain the haloimidazoline intermediate.

[0016] S3, Coupling reaction grafting hydrophobic long chains: Under an inert atmosphere, perfluoropolyether bromide is dissolved in THF, and n-butyllithium is added dropwise at -78℃. The mixture is then stirred for 1-2 hours to obtain PFPE-lithium reagent. A haloimidazoline intermediate is dissolved in THF, and PFPE-lithium reagent is added dropwise to the haloimidazoline intermediate solution at -78℃. The reaction is carried out for 3-4 hours, followed by separation and purification to obtain modified imidazoline containing hydrophobic long chains. The molar ratio of perfluoropolyether bromide to n-butyllithium solution is 1:1.2, and the molar ratio of haloimidazoline intermediate to PFPE-lithium reagent is 1:1.1.

[0017] S4, Quaternization reaction: Modified imidazoline and benzyl halide are mixed in a molar ratio of 1:1.2, reacted at 80-90℃ for 3-5 hours, and then separated and purified to obtain the product.

[0018] This invention employs the synergistic effect of multiple components. Specifically, a barrier layer is formed on the pipe wall by a nano-titanium dioxide / graphene composite, effectively blocking corrosive media; fluorinated polyether-modified imidazoline quaternary ammonium salt effectively inhibits electrochemical corrosion and also provides sterilization, exhibiting multiple anti-corrosion effects; polyaspartic acid derivatives have good anti-corrosion and scale-inhibiting effects; plant essential oil microcapsules provide long-lasting antibacterial effects; and fluorocarbon surfactants reduce the surface tension of the agent, improving its wetting and spreading properties on the pipe inner wall, ensuring uniform agent coverage.

[0019] One embodiment of the present invention comprises the following steps for the separation and purification of the hydroxylated imidazoline intermediate: taking the reaction product, adding dichloromethane and extracting it at 0-10°C, taking the dichloromethane layer, and distilling it under reduced pressure to obtain the product; the separation and purification of the halogenated imidazoline intermediate comprises the following steps: taking the reaction product, adding dichloromethane and extracting it, taking the dichloromethane layer, and distilling it under reduced pressure to obtain the product; the separation and purification of the modified imidazoline containing the hydrophobic long chain comprises the following steps: removing the reaction product, adding dichloromethane and extracting it, taking the dichloromethane layer, and distilling it under reduced pressure to obtain the product; the separation and purification steps after the quaternization reaction are as follows: taking the product, removing low-boiling substances by reduced pressure distillation, then washing the product with diethyl ether or petroleum ether, and drying it after washing to obtain the product.

[0020] One embodiment of the present invention comprises the following steps for the synthesis of the imidazoline intermediate: adding citric acid and triethylenetetramine to a reactor, using xylene as a solvent, refluxing at 140-160°C for 2 hours, then raising the temperature to 200-230°C and continuing the reaction for 4-6 hours, obtaining a first intermediate after the reaction, adding hydrogen peroxide and acetic anhydride dropwise to the reaction solution, reacting at 0-25°C for 3 hours, and obtaining a hydroxylated imidazoline intermediate after separation and purification, wherein the molar ratio of the first intermediate, hydrogen peroxide and acetic anhydride is 1:1.2:0.5.

[0021] One embodiment of the present invention is that the nano-titanium dioxide / graphene composite is prepared by the following method:

[0022] Anatase nano-titanium dioxide and graphene oxide were added to an ethanol solution at a mass ratio of 2:1 to 4:1.

[0023] After ultrasonic dispersion, add silane coupling agent KH550 and stir at 70-90℃ for 3-5 hours;

[0024] The solid phase is obtained by drying.

[0025] One embodiment of the present invention involves encapsulating the plant essential oil microcapsules using a complex coagulation method. The wall material is a mixture of gum arabic and gelatin at a mass ratio of 1:2, with a core-to-wall ratio of 1:1.5-1:2.5. The curing conditions are: pH 4.0-5.0, temperature 2-6°C, and cross-linking time 2-3 hours. The preparation method of the plant essential oil microcapsules is a conventional method in the art, and therefore will not be described in detail here. Commercially available products are also readily available.

[0026] One embodiment of the present invention is that the core material of the plant essential oil microcapsules is cinnamaldehyde.

[0027] One embodiment of the present invention is that the fluorocarbon surfactant includes one or more of perfluorohexyl ethyl propyl ether, perfluoromethyl vinyl ether, sodium perfluorononenoxybenzenesulfonate, and modified sodium perfluorohexylbenzenesulfonate.

[0028] One embodiment of the present invention is that the polyaspartic acid derivative includes one or more of polyaspartic acid-g-polycaprolactone, carboxylic acid polyaspartic acid derivative, and polyaspartic acid-g-PEG.

[0029] Another object of the present invention is to disclose a method for preparing the above-mentioned bactericidal and antiseptic agent for natural gas pipelines, comprising the following steps:

[0030] The first step is to add the nano-titanium dioxide / graphene composite, polyaspartic acid derivative and fluorocarbon surfactant to the solvent according to the formula, and stir at 40-50℃ for 1-2 hours.

[0031] The second step is to add fluorinated polyether-modified imidazoline quaternary ammonium salt and plant essential oil microcapsules, and continue stirring for 2-3 hours;

[0032] The third step involves processing the agent using a high-pressure homogenizer at a pressure of 15-25 MPa to obtain a uniform emulsion.

[0033] In one embodiment of the present invention, the pH of the mixture needs to be adjusted to 7.5-8.5 before the high-pressure homogenization process, and the homogenization temperature needs to be controlled at 30-40℃.

[0034] Compared with the prior art, the beneficial effects of the present invention are:

[0035] 1. The agent of the present invention has good bactericidal and antiseptic effects, with a bactericidal rate of over 99% and a corrosion rate reduced to below 0.028 mm / a; at the same time, it can provide long-lasting bactericidal and antiseptic effects, with an action time of over 180 days after a single addition.

[0036] 2. The reagent of the present invention has good environmental performance and a high biodegradability rate, which meets the current environmental protection requirements. Detailed Implementation

[0037] The principles and features of the present invention are described below with reference to examples. The examples are only used to explain the present invention and are not intended to limit the scope of the present invention.

[0038] Unless otherwise specified, all percentages mentioned in the following embodiments are mass percentages.

[0039] Unless otherwise specified, the experimental procedures described in the following embodiments are all conventional operations in the art.

[0040] Unless otherwise specified, the pharmaceutical agents used in the following examples are all conventional commercial products in the art.

[0041] In the following examples, the perfluoropolyether bromide used was prepared by the method disclosed in patent CN1166506A "Method for preparing perfluoropolyethers with bromine or iodine end groups".

[0042] Example 1

[0043] A bactericide and antiseptic agent for natural gas pipelines, comprising the following components by weight percentage:

[0044] The composition consists of 15% fluorinated polyether-modified imidazoline quaternary ammonium salt, 8% nano-titanium dioxide / graphene composite, 5% polyaspartic acid-g-polycaprolactone, 2% sodium perfluorononenoxybenzenesulfonate fluorocarbon surfactant, 3% plant essential oil microcapsules, and the remainder is water.

[0045] The preparation method of this drug includes the following steps:

[0046] The first step involves adding the nano-titanium dioxide / graphene composite, polyaspartic acid derivative, and fluorocarbon surfactant to water according to the specified ratio, and stirring at 40°C for 1 hour.

[0047] The second step involves adding fluorinated polyether-modified imidazoline quaternary ammonium salt and plant essential oil microcapsules, and continuing to stir for 2 hours to obtain a mixture.

[0048] The third step is to adjust the pH of the mixture to 7.5 and control the homogenization temperature to 35°C. The mixture is then processed by a high-pressure homogenizer at a pressure of 25 MPa to obtain a homogeneous emulsion.

[0049] The preparation method of fluorinated polyether modified imidazoline quaternary ammonium salt is as follows:

[0050] S1, Synthesis of imidazoline intermediate: Citric acid and triethylenetetramine were added to a reactor in a molar ratio of 1:3.5. Using xylene as solvent, the mixture was refluxed at 150°C for 2 hours, then heated to 210°C and reacted for another 5 hours to close the amide intermediate into an imidazoline structure containing three five-membered rings. Hydrogen peroxide and acetic anhydride were then slowly added dropwise, ensuring good ventilation and stirring. The molar ratio of imidazoline containing three five-membered rings to hydrogen peroxide to acetic anhydride was 1:1.2:0.5. The mixture was reacted at 10°C for 3 hours. After separation and purification, a hydroxylated imidazoline intermediate was obtained. The separation and purification steps were as follows: The initially obtained hydroxylated imidazoline intermediate was transferred to a separatory funnel, and dichloromethane was added as an extractant. The mixture was shaken thoroughly to dissolve the hydroxylated imidazoline intermediate in the extractant. The separatory funnel was allowed to stand until the solution separated into layers. The extract containing the product was collected in a rotary evaporator flask for rotary evaporation to remove the extractant, yielding a purer hydroxylated imidazoline intermediate.

[0051] S2, Substitution reaction to introduce halogen groups: The hydroxylated imidazoline intermediate is mixed with hydroiodic acid at a molar ratio of 1:1.2 and reacted at 30°C for 4 hours. The halogen in the hydroiodic acid replaces the hydroxyl group on the imidazoline ring. After separation and purification, the haloimidazoline intermediate is obtained.

[0052] The separation and purification steps are as follows: the initially obtained haloimidazoline intermediate is transferred to a separatory funnel, dichloromethane extractant is added, and the mixture is shaken thoroughly to dissolve the hydroxylated imidazoline intermediate in the extractant; the separatory funnel is allowed to stand until the solution separates into layers, and the extract containing the product is released and collected in a flask of a rotary evaporator for rotary evaporation to remove the extractant and obtain a purer haloimidazoline intermediate;

[0053] S3, Coupling reaction grafting hydrophobic long chain: Under nitrogen protection, perfluoropolyether bromide is dissolved in anhydrous THF, cooled to -78°C, and then a pre-cooled n-butyllithium solution is slowly added dropwise. The molar ratio of perfluoropolyether bromide to n-butyllithium solution is 1:1.2. The reaction is stirred for 1 hour to obtain PFPE-lithium reagent. The haloimidazoline intermediate is dissolved in anhydrous THF, cooled to -78°C, and a pre-prepared PFPE-lithium reagent solution is slowly added. The molar ratio of haloimidazoline intermediate to PFPE-lithium reagent is 1:1.1. The reaction is stirred for 3 hours. The fluorinated alkyl group in the perfluoropolyether bromide replaces the halogen group in the intermediate. After separation and purification, a modified imidazoline containing a hydrophobic long chain is obtained.

[0054] Specifically, the modified imidazoline containing hydrophobic long chains was obtained through separation and purification. The modified imidazoline was transferred to a separatory funnel, and dichloromethane extractant was added. The mixture was shaken thoroughly to dissolve the hydroxylated imidazoline intermediate in the extractant. The separatory funnel was allowed to stand until the solution separated into layers. The extract containing the product was then released and collected in a flask of a rotary evaporator for rotary evaporation to remove the extractant and obtain a purer modified imidazoline.

[0055] S4, Quaternization reaction introduces antibacterial groups: Modified imidazoline and benzyl halide are mixed in a molar ratio of 1:1.2 and reacted at 85°C for 3 hours. The benzyl group in benzyl halide combines with the nitrogen atom on the imidazoline ring to form a quaternary ammonium salt structure. At the same time, a benzene ring is introduced to enhance the antibacterial activity.

[0056] S5, Post-processing and purification: After the reaction was completed, low-boiling substances were removed by vacuum distillation, and the product was washed several times with diethyl ether to remove residual impurities, yielding fluorinated polyether modified imidazoline quaternary ammonium salt.

[0057] The nano-titanium dioxide / graphene composite was prepared by the following method: anatase nano-titanium dioxide and graphene oxide were added to an ethanol solution at a mass ratio of 2:1 and ultrasonically dispersed. Then, silane coupling agent KH550 was added, and the mixture was stirred at 70°C for 3 hours. After vacuum drying, a composite with a particle size of 80 nm was obtained.

[0058] The plant essential oil microcapsules are encapsulated using a complex coagulation method. The wall material is a mixture of gum arabic and gelatin, and the core material is cinnamaldehyde. The core-to-wall ratio is 1:1.5. The curing conditions are: pH 4.0, temperature 2℃, and cross-linking time 2 hours.

[0059] The properties of the reagent prepared in this embodiment were measured as follows: static viscosity at 25°C was 15 mPa·s; shear thinning index was 0.2; tube wall contact angle at 25°C was 11°; and surface tension of the reagent at 25°C was 22 mN / m.

[0060] Example 2

[0061] A bactericide and antiseptic agent for natural gas pipelines, comprising the following components by weight percentage:

[0062] Fluorine-containing polyether modified imidazoline quaternary ammonium salt 20%; nano titanium dioxide / graphene composite 10%; polyaspartic acid-g-PEG 8%; fluorocarbon surfactant sodium perfluorononenoxybenzenesulfonate 3%; plant essential oil microcapsules 6%; the remainder is deionized water, to make up 100%.

[0063] The preparation methods of the pharmaceutical preparation and its components are the same as in Example 1.

[0064] The properties of the reagent prepared in this embodiment were measured as follows: static viscosity at 25°C was 16.5 mPa·s; shear thinning index was 0.2; tube wall contact angle at 25°C was 14°; and surface tension of the reagent at 25°C was 22 mN / m.

[0065] Example 3

[0066] A bactericide and antiseptic agent for natural gas pipelines, comprising the following components by weight percentage:

[0067] Fluorine-containing polyether modified imidazoline quaternary ammonium salt 25%; nano titanium dioxide / graphene composite 12%; polyaspartic acid-g-polycaprolactone 10%; fluorocarbon surfactant sodium perfluorononenoxybenzenesulfonate 5%; plant essential oil microcapsules 8%; the remainder is deionized water, to make up 100%.

[0068] The preparation methods of the pharmaceutical preparation and its components are the same as in Example 1.

[0069] The properties of the reagent prepared in this embodiment were measured as follows: static viscosity at 25°C was 15.5 mPa·s; shear thinning index was 0.2; tube wall contact angle at 25°C was 13°; and surface tension of the reagent at 25°C was 22.6 mN / m.

[0070] Example 4

[0071] A bactericide and antiseptic agent for natural gas pipelines, comprising the following components by weight percentage:

[0072] Fluorine-containing polyether modified imidazoline quaternary ammonium salt 23%; nano titanium dioxide / graphene composite 11%; polyaspartic acid-g-polycaprolactone 9%; fluorocarbon surfactant sodium perfluorononenoxybenzenesulfonate 4%; plant essential oil microcapsules 7%; the remainder is deionized water, to make up 100%.

[0073] The preparation methods of the pharmaceutical preparation and its components are the same as in Example 1.

[0074] The properties of the reagent prepared in this embodiment were measured as follows: static viscosity at 25°C was 16 mPa·s; shear thinning index was 0.15; tube wall contact angle at 25°C was 12°; and surface tension of the reagent at 25°C was 22.4 mN / m.

[0075] The agents described in Examples 1-4 were used to test the sterilization rate, corrosion rate, and maintenance cycle of the pipeline. The agent dosage was 80 g / m. 2 The sterilization rate was tested according to GB / T 14643.5-2009, the corrosion rate was tested according to NACETM0177-2016, and the maintenance cycle was tested by the activity of the agent. The results are shown in the table below:

[0076] Sterilization rate Corrosion rate Maintenance cycle Example 1 ≥99.5％ ≤0.028mm / a 182 days Example 2 ≥99.8％ ≤0.025mm / a 180 days Example 3 ≥99.3％ ≤0.027mm / a 182 days Example 4 ≥99.1％ ≤0.023mm / a 184 days

[0077] As can be seen from the table above, the agent of the present invention has excellent bactericidal and preservative functions;

[0078] In the reagent, the nano-titanium dioxide / graphene composite forms a three-dimensional conductive framework through π-π conjugation, which can form a dense conductive film on the pipe wall to block corrosive media; the fluorinated polyether-modified imidazoline quaternary ammonium salt forms an adsorption film on the metal surface, inhibiting electrochemical reactions, and the quaternary ammonium salt molecules can destroy bacterial cell membranes through electrostatic interactions; the fluorocarbon surfactant forms a superhydrophobic interface with a contact angle of up to 150°, effectively preventing the formation of condensate film in natural gas pipelines and improving the adhesion rate of the reagent to the pipe wall, solving the problem of protective failure caused by high-speed airflow erosion; the side chain carboxyl groups of the polyaspartic acid derivative can chelate Fe2+. + / Cu2 +Metal ions prevent the formation of corrosion micro-batteries from deposits, effectively preventing corrosion of natural gas pipelines; plant essential oil microcapsules enable the slow and continuous release of bactericidal components in the medicine, effectively extending the bactericidal time of the medicine.

[0079] This invention is applicable to pipelines: natural gas gathering and transmission pipelines made of carbon steel and stainless steel, and is especially suitable for corrosive environments containing water and hydrogen sulfide;

[0080] Maintenance cycle: The protection period after a single addition is up to 180 days, which is 3-6 times more efficient than traditional agents (30-60 days).

[0081] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Those skilled in the art can readily implement the present invention according to the description and above. However, any modifications, alterations, or variations made by those skilled in the art without departing from the scope of the present invention, based on the disclosed technical content, are equivalent embodiments of the present invention. Furthermore, any modifications, alterations, or variations made to the above embodiments based on the essential technology of the present invention are still within the protection scope of the present invention.

Claims

1. A bactericide and antiseptic agent for natural gas pipelines, characterized in that, It consists of the following components by mass percentage: Fluorine-containing polyether modified imidazoline quaternary ammonium salt 15-25%; Nano-titanium dioxide / graphene composite 8-12%; 5-10% polyaspartic acid derivatives; Fluorocarbon surfactants 2-5%; Plant essential oil microcapsules 3-8%; The rest is deionized water; The fluorinated polyether-modified imidazoline quaternary ammonium salt is prepared by the following steps: S1, Synthesis of imidazoline intermediate: Citric acid and triethylenetetramine in a molar ratio of 1:3.5 were used to prepare hydroxylated imidazoline intermediate by dehydration condensation; S2, Substitution reaction to introduce halogen groups: The hydroxylated imidazoline intermediate is mixed with hydroiodic acid at a molar ratio of 1:1.2 and reacted at 30-35℃ for 3-5 hours. The intermediate is then separated and purified to obtain the haloimidazoline intermediate. S3, Coupling reaction grafting hydrophobic long chains: Under an inert atmosphere, perfluoropolyether bromide is dissolved in THF, and n-butyllithium is added dropwise at -78℃. The mixture is then stirred for 1-2 hours to obtain PFPE-lithium reagent. A haloimidazoline intermediate is dissolved in THF, and PFPE-lithium reagent is added dropwise to the haloimidazoline intermediate solution at -78℃. The reaction is carried out for 3-4 hours, followed by separation and purification to obtain modified imidazoline containing hydrophobic long chains. The molar ratio of perfluoropolyether bromide to n-butyllithium solution is 1:1.2, and the molar ratio of haloimidazoline intermediate to PFPE-lithium reagent is 1:1.

1. S4, Quaternization reaction: Modified imidazoline and benzyl halide are mixed in a molar ratio of 1:1.2, reacted at 80-90℃ for 3-5 hours, and then separated and purified to obtain the product.

2. The bactericidal and antiseptic agent for natural gas pipelines according to claim 1, characterized in that, The separation and purification of the hydroxylated imidazoline intermediate includes the following steps: taking the reaction product, adding dichloromethane and extracting it at 0-10℃, taking the dichloromethane layer, and distilling it under reduced pressure to obtain the product; the separation and purification of the halogenated imidazoline intermediate includes the following steps: taking the reaction product, adding dichloromethane and extracting it, taking the dichloromethane layer, and distilling it under reduced pressure to obtain the product; the separation and purification of the modified imidazoline containing hydrophobic long chains includes the following steps: taking the reaction product, adding dichloromethane and extracting it, taking the dichloromethane layer, and distilling it under reduced pressure to obtain the product; the separation and purification steps after the quaternization reaction are as follows: taking the product, removing low-boiling substances by reduced pressure distillation, then washing the product with diethyl ether or petroleum ether, and drying it after washing to obtain the product.

3. The bactericidal and antiseptic agent for natural gas pipelines according to claim 1, characterized in that, The synthesis of the imidazoline intermediate includes the following steps: citric acid and triethylenetetramine are added to a reactor, and xylene is used as a solvent. The mixture is refluxed at 140-160℃ for 2 hours, then heated to 200-230℃ and reacted for another 4-6 hours. After the reaction is complete, the first intermediate is obtained. Hydrogen peroxide and acetic anhydride are added dropwise to the reaction solution, and the mixture is reacted at 0-25℃ for 3 hours. After separation and purification, the hydroxylated imidazoline intermediate is obtained. The molar ratio of the first intermediate, hydrogen peroxide, and acetic anhydride is 1:1.2:0.

5.

4. The bactericidal and antiseptic agent for natural gas pipelines according to claim 1, characterized in that, The nano-titanium dioxide / graphene composite was prepared by the following method: Anatase nano-titanium dioxide and graphene oxide were added to an ethanol solution at a mass ratio of 2:1 to 4:

1. After ultrasonic dispersion, add silane coupling agent KH550 and stir at 70-90℃ for 3-5 hours; The solid phase is obtained by drying.

5. A bactericide and antiseptic agent for natural gas pipelines according to claim 1, characterized in that, The plant essential oil microcapsules are encapsulated using a complex coagulation method. The wall material is a mixture of gum arabic and gelatin with a mass ratio of 1:2, and the core-to-wall ratio is 1:1.5-1:2.

5. The curing conditions are: pH 4.0-5.0, temperature 2-6℃, and cross-linking time 2-3 hours.

6. A bactericide and antiseptic agent for natural gas pipelines according to claim 1 or 5, characterized in that, The core material of the plant essential oil microcapsules is cinnamaldehyde.

7. A bactericide and antiseptic agent for natural gas pipelines according to claim 1, characterized in that, The fluorocarbon surfactant includes one or more of perfluorohexyl ethyl propyl ether, perfluoromethyl vinyl ether, sodium perfluorononenoxybenzenesulfonate, and modified sodium perfluorohexylbenzenesulfonate.

8. A bactericide and antiseptic agent for natural gas pipelines according to claim 1, characterized in that, The polyaspartic acid derivatives include one or more of polyaspartic acid-g-polycaprolactone, carboxylic acid polyaspartic acid derivatives, and polyaspartic acid-g-PEG.

9. A method for preparing a bactericidal and antiseptic agent for natural gas pipelines according to any one of claims 1-8, characterized in that, Includes the following steps: The first step is to add the nano-titanium dioxide / graphene composite, polyaspartic acid derivative and fluorocarbon surfactant to the solvent according to the formula, and stir at 40-50℃ for 1-2 hours. The second step is to add fluorinated polyether-modified imidazoline quaternary ammonium salt and plant essential oil microcapsules, and continue stirring for 2-3 hours; The third step involves processing the agent using a high-pressure homogenizer at a pressure of 15-25 MPa to obtain a uniform emulsion.

10. A method for preparing a bactericidal and antiseptic agent for natural gas pipelines according to claim 9, characterized in that, Before the high-pressure homogenization process, the pH of the mixture needs to be adjusted to 7.5-8.5, and the homogenization temperature needs to be controlled at 30-40℃.