A sulfur-dissolving composition, a sulfur-dissolving agent, and use thereof

Abstract

The present application relates to a kind of sulfur-dissolving composition, sulfur-dissolving agent and its application, belong to oil and gas field chemical technical field.The sulfur-dissolving composition of the present application includes high branched polymer, amino modified nanomaterial, organic amine solvent and inorganic base catalyst;The molecular chain end of the high branched polymer has at least 3 or more amino groups;The inorganic base catalyst is water-soluble sulfide salt and / or water-soluble sulfhydryl salt.The sulfur-dissolving composition of the present application has strong sulfur-dissolving capacity, and amino modified nanomaterial has selective solubility to sulfur particles, and has higher compatibility with organic amine solvent.Amino modified nanomaterial has higher specific surface area, and is dispersed in organic amine solution, to provide abundant active sites for reaction with sulfur particles, reaction area increases, and the solubility of sulfur is improved;At the same time, the strong adsorption of amino modified nanomaterial reduces the mass transfer distance between sulfur molecules, and greatly improves the solubility of sulfur.

Description

Technical Field

[0001] This invention relates to a sulfur-dissolving composition, a sulfur-dissolving agent, and their applications, belonging to the field of oil and gas field chemicals technology. Background Technology

[0002] High-sulfur natural gas employs a throttling and depressurization wet gas gathering and transportation process. Natural gas from the wellhead first enters the gathering station, where it is heated, throttled, and metered before being transported out. During the throttling and depressurization process of high-sulfur natural gas, changes in operating conditions and flow patterns occur, causing sulfur molecules in the natural gas to precipitate and form elemental sulfur. When these elemental sulfur particles encounter the rough walls of pipes or equipment, some particles collide with the walls and adsorb onto the inner walls, combining with other impurities to form sulfur deposits. This process gradually builds up over time, forming a sulfur scale layer. This scale layer can clog the production zone, wellbore, and gathering and transportation pipelines. Severe sulfur scale buildup can block pipelines and equipment, leading to increased pressure in pressure vessels and pipelines within the gathering and transportation system, causing level gauges, pressure sensors, gas flow meters, etc., to exceed their safe operating limits, thus affecting the safe operation of the gathering and transportation system. Therefore, high-sulfur natural gas gathering stations need to undergo regular comprehensive cleaning and maintenance to remove harmful substances such as sulfur scale from equipment and pipelines, eliminate potential problems during operation, and ensure the safe and stable operation of the sulfur-containing gas field gathering and transportation system.

[0003] Currently, sulfur dissolution cleaning technology at gas gathering stations in sulfur-containing natural gas fields mainly involves injecting sulfur-dissolving agents. Injecting sulfur-dissolving agents is currently the most direct and reliable method for inhibiting sulfur deposition and removing sulfur deposit blockages. Using sulfur-dissolving agents as cleaning agents, the agents are injected into the gathering and transmission system. The agents and water are heated to a certain temperature, causing a physicochemical reaction between the agents and the sulfur scale. After the sulfur scale on the inner wall of the pipeline dissolves, it is discharged into a wastewater tank using a circulating cleaning pump, thus achieving the purpose of desulfurization cleaning at gas gathering stations in sulfur-containing natural gas fields.

[0004] Sulfur solvents can be classified into two categories based on whether a chemical reaction occurs when they dissolve sulfur: physical sulfur solvents and chemical sulfur solvents. Generally, physical sulfur solvents dissolve less sulfur than chemical sulfur solvents. Commonly used physical sulfur solvents include paraffin-based mineral oils, aromatic hydrocarbons, cycloalkanes, carbon tetrachloride, and carbon disulfide. These are generally only used to treat moderate amounts of sulfur deposits; this method is not suitable for large amounts of sulfur deposits.

[0005] Chemical sulfur solvents are suitable for situations with large sulfur deposits and have better sulfur-dissolving capabilities than physical sulfur solvents. The most commonly used solvents include disulfides, amines, and inorganic bases. Organic disulfide-based sulfur solvent systems (generally with dimethyl disulfide as the main agent) currently offer the best solubility for elemental sulfur. However, organic disulfides are expensive, highly volatile, have a pungent odor, are highly toxic, and easily adsorb onto clothing and hair, posing a risk to the safety and health of on-site operators. Furthermore, the recycling and regeneration process is complex and can cause serious environmental damage. For example, Chinese patent application CN105154047A discloses a novel high-performance sulfur solvent suitable for high-sulfur gas fields. The main solvent is a dimethyl disulfide organic disulfide. This system incorporates a co-catalyst with an aromatic structure and a phase-transfer catalyst of organic amines, significantly improving the sulfur-dissolving capacity and reducing costs. However, it does not solve the problems of high volatility, pungent odor, and high toxicity associated with organic disulfides.

[0006] Inorganic alkaline sulfur solvents mainly use sodium hydroxide solution as the main agent. The reaction mechanism is mainly the reaction between sulfur and sodium hydroxide. The reaction product, Na₂S, has a good physical sulfur dissolution effect. However, sodium hydroxide solution is highly corrosive, and its large-scale use on site poses a high safety risk to the environment and human health. For example, Chinese patent document CN102408886B discloses a highly efficient, odorless sulfur solvent composed of sulfolane, N-methylpyrrolidone, and N,N-dimethylformamide, with sodium hydroxide aqueous solution as the main agent. This system of sulfur solvents can dissolve 1.15g of sulfur per gram at room temperature, and has advantages such as high sulfur dissolution performance, low irritation, no odor, and low cost. However, inorganic alkaline solutions are highly alkaline and corrosive, posing a high safety risk in field applications.

[0007] Amine solvents that do not contain organic disulfides can also be used as sulfur solvents, offering advantages such as low odor and low toxicity. However, some sulfur solvents with amine solvents as the main component currently have low sulfur solubility, far lower than those using organic disulfide systems, and cannot meet on-site requirements. For example, Chinese patent application CN108084980A discloses a highly efficient primary amine sulfur solvent prepared from primary amine compounds, dimethyl sulfoxide, polyethylenepolyamine, and a Lewis base catalyst, which has the advantages of being odorless, low-cost, and non-corrosive. Under room temperature conditions, 1g of this solvent can dissolve more than 0.9g of sulfur. However, dimethyl sulfoxide accounts for 75-80% of the formulation, exhibiting certain toxicity, and its volatilization should be avoided during use. Summary of the Invention

[0008] The purpose of this invention is to provide a sulfur-dissolving composition that is low in toxicity, has strong sulfur-dissolving ability, and is safe and environmentally friendly.

[0009] A second objective of this invention is to provide a sulfur solvent.

[0010] A third objective of this invention is to provide a sulfur-dissolving composition or sulfur-dissolving agent for use as a cleaning agent in surface gathering and transportation systems for sulfur-containing gas fields.

[0011] To achieve the above objectives, the technical solution adopted by the sulfur-dissolving composition of the present invention is as follows:

[0012] A sulfur-dissolving composition comprises a highly branched polymer, an amino-modified nanomaterial, an organic amine solvent, and an inorganic base catalyst; wherein the highly branched polymer has at least three amino groups at the ends of its molecular chains; the amino-modified nanomaterial is a nanomaterial with amino groups bonded to its surface; the nanomaterial is a carbon nanomaterial; the inorganic base catalyst is a water-soluble sulfide salt and / or a water-soluble hydrosulfide salt; and the mass ratio of the highly branched polymer, the amino-modified nanomaterial, the organic amine solvent, and the inorganic base catalyst is 5:(0.1-0.3):(20-30):(2-3).

[0013] The sulfur-dissolving composition of this invention has strong sulfur-dissolving ability, and the raw materials used are low in toxicity, corrosiveness, and irritation, meeting the requirements of green environmental protection. The abundant intramolecular cavities of the highly branched polymer determine that its molecular chains are not entangled, resulting in advantages such as high solubility, low viscosity, and good dispersibility. It can stably disperse amino-modified nanomaterials and sulfur particles, expand the contact area, and promote easier dissolution of sulfur, thus having a dispersing and synergistic effect. Furthermore, the highly branched polymer itself is non-volatile and non-irritating, making it safer and more environmentally friendly. The amino-modified nanomaterials exhibit selective solubility for sulfur particles (the surface of the amino-modified nanomaterials contains a large number of amino groups, which promote sulfur dissolution through chemical reactions with sulfur ions; the principle is: RNH2 + S → R = NH + H2S, RNH2 + H2S → RNH3). + HS - RNH3 + HS - +xS→RNH3 + HS - x+1Furthermore, it exhibits high compatibility with organic amine solvents. The amino-modified nanomaterials possess a high specific surface area, dispersing and interspersing within the organic amine solution, providing abundant active sites for reaction with sulfur particles, increasing the reaction area, and enhancing the sulfur solubility. Simultaneously, the strong adsorption properties of the amino-modified nanomaterials reduce the mass transfer distance between them and sulfur molecules, significantly improving the sulfur solubility. Inorganic base catalysts can provide sulfide ions or form sulfide ions through reaction with organic amine solvents or amino groups in highly branched polymers, which then react with elemental sulfur to form polysulfide adducts, thus dissolving it. When used to clean sulfur-containing gas field surface gathering and transportation systems, the sulfur-dissolving composition of this invention exhibits strong sulfur-dissolving ability, no strong irritation, no malodor, low toxicity, and is safer and more environmentally friendly. It not only does not corrode the gathering and transportation system but also has a certain anti-corrosion effect, enabling efficient and safer environmentally friendly sulfur-dissolving cleaning of sulfur-containing gas field surface gathering and transportation systems.

[0014] Preferably, the molecular chain ends of the highly branched polymer have at least three primary amino groups.

[0015] Preferably, the carbon nanomaterial is selected from one or any combination of carbon fiber, carbon nanotube, carbon black, and graphene.

[0016] Preferably, the amino-modified nanomaterial is amino-modified carbon nanotube and / or amino-modified graphene oxide.

[0017] Preferably, the amino-modified carbon nanotubes are prepared by amidation reaction of an amine compound and carboxylated carbon nanotubes; the amine compound has at least two amino groups. Preferably, the amine compound has at least two primary amino groups.

[0018] Preferably, the carboxylated carbon nanotubes are prepared by a method comprising the following steps: heating a mixture of carbon nanotubes, concentrated sulfuric acid, and concentrated nitric acid; performing solid-liquid separation on the heated system; and then removing acidic compounds and water from the solid obtained after solid-liquid separation to obtain carboxylated carbon nanotubes. Preferably, the mass ratio of carbon nanotubes, concentrated sulfuric acid, and concentrated nitric acid is 1:100:33. Preferably, the heating temperature is 30–50°C, and the heating time is 3 hours. For example, the heating temperature is 40°C, and the heating time is 3 hours. Preferably, the carbon nanotubes are multi-walled carbon nanotubes with a diameter of 40–60 nm and a length of 5–15 μm.

[0019] Solid-liquid separation can be performed by centrifugation or filtration. To reduce costs, filtration is preferred. Preferably, the solid obtained from solid-liquid separation is sequentially washed and dried to remove acidic compounds and water. Water is used as the washing agent. To determine if the washing is satisfactory, the pH of the washing solution can be tested. If the pH is close to 7, it indicates that the acidic compounds in the solid have been completely removed. It is understood that the acidic compounds are sulfuric acid and nitric acid. It is understood that the carbon nanotubes are single-walled carbon nanotubes, double-walled carbon nanotubes, or multi-walled carbon nanotubes.

[0020] Preferably, the amine compounds used to prepare amino-modified carbon nanotubes and the amine compounds used to prepare amino-modified graphene oxide are independently selected from one or any combination of ethylenediamine, hexamethylenediamine, and decanediamine. Preferably, the amount of amine compound used is excessive.

[0021] To enable carboxylated carbon nanotubes to undergo an amidation reaction with amine compounds, the reaction system consisting of carboxylated carbon nanotubes and amine compounds can be directly heated to induce an amidation reaction between the carboxyl groups on the surface of the carboxylated carbon nanotubes and the amino groups of the amine compounds. Alternatively, a catalyst can be added to the reaction system to promote the amidation reaction. To improve the reactivity of the carboxyl groups, the carboxyl groups on the surface of the carboxylated carbon nanotubes can be converted into acyl chloride groups before undergoing an amidation reaction with amine compounds.

[0022] It is understood that an amidation reaction can occur without a catalyst, or a catalyst can be used to lower the temperature and shorten the reaction time. For example, the catalyst could be a HATU condensation reagent. HATU condensation reagents are commonly used in the synthesis of amide bonds; HATU promotes amide bond formation by activating the carboxyl group. The systematic name of the HATU condensation reagent is 2-(7-azabenzotriazole)-N,N,N',N'-tetramethylurea hexafluorophosphate.

[0023] Preferably, the amidation reaction method includes the following steps: heating a mixed system consisting of carboxylated carbon nanotubes, amine compounds, and HATU condensation reagent to 40°C for the amidation reaction; the amidation reaction time is 4 hours. Preferably, after the amidation reaction, the system after the amidation reaction is sequentially washed, subjected to solid-liquid separation, and dried to obtain amino-modified carbon nanotubes. Preferably, in the preparation method of amino-modified carbon nanotubes, the solid-liquid separation is centrifugation; the washing agent used is water; the drying temperature is 60°C, and the drying time is 8 hours. Preferably, the volume of amine compound used for each 0.1g of carboxylated carbon nanotubes is 60mL. When the amine compound is ethylenediamine, the synthetic route of amino-modified carbon nanotubes is shown in Formula 1:

[0024]

[0025] In Formula 1, CNTs represent carbon nanotubes, carboxylated CNTs represent carboxylated carbon nanotubes, EDA represents ethylenediamine, and EDA-CNTs represent amino-modified carbon nanotubes synthesized using ethylenediamine.

[0026] Preferably, the amino-modified graphene oxide is prepared by a condensation reaction of an amino group in an amine compound and a carboxyl group in graphene oxide; the amine compound has at least two amino groups. Preferably, in the preparation method of amino-modified graphene oxide, the amine compound has at least two primary amino groups. It is understood that the condensation reaction refers to a dehydration condensation reaction between an amino group and a carboxyl group.

[0027] Preferably, the graphene oxide is prepared by a method comprising the following steps: mixing 3.7 parts by mass of potassium permanganate, 1 part by mass of graphite powder, 1 part by mass of sodium nitrate, and 25 parts by mass of concentrated sulfuric acid at a temperature below 15°C for 2 hours; then heating to 30–40°C and continuing the mixing reaction for 1 hour; then adding 30–40 parts by mass of water; then heating to 90°C and mixing reaction for 30 minutes; finally adding water and hydrogen peroxide to terminate the reaction, resulting in a suspension; then performing solid-liquid separation, washing, and drying to obtain graphene oxide. Preferably, in the method for preparing graphene oxide, the solid-liquid separation is filtration; the washing agent includes dilute hydrochloric acid and water; and the drying temperature is 40°C for 24 hours.

[0028] Preferably, the condensation reaction method includes the following steps: heating graphene oxide, amine compounds, and a dehydrating condensing agent in a solvent to 55–65°C and reacting for 5–7 hours. For example, the condensation reaction method includes the following steps: heating graphene oxide, amine compounds, and a dehydrating condensing agent in a solvent to 60°C and reacting for 6 hours. Preferably, the dehydrating condensing agent is N,N′-dicyclohexylcarboimide. Preferably, the mass ratio of graphene oxide, amine compounds, and the dehydrating condensing agent is 1:150:25. Preferably, the solvent is N,N-dimethylformamide. Preferably, the mass ratio of graphene oxide to solvent is 1:1000. The condensation reaction method further includes the following steps: after the mixing reaction is completed, adding ethanol to the mixed reaction system, allowing it to stand, separating the solid and liquid phases, washing, and drying to obtain amino-modified graphene oxide. Preferably, in the condensation reaction method, the solid-liquid separation is filtration; the washing agent includes ethanol and water; and the drying temperature is 60°C. When the amine compound is ethylenediamine, the synthetic route for amino-modified graphene oxide is shown in Formula 2:

[0029]

[0030] In Formula 2, GO represents graphene oxide, EDA represents ethylenediamine, DCC represents an organic synthesis dehydration condensing agent (N,N′-dicyclohexylcarboimide), and GO-NH2 represents amino-modified graphene oxide synthesized using ethylenediamine.

[0031] It is important to understand that highly branched polymers refer to polymers whose molecular structure contains a large number of branching units. Specifically, highly branched polymers include dendritic polymers and hyperbranched polymers.

[0032] Dendritic polymers are linear polymers with dendritic units on each repeating unit. They possess precise molecular structures, high geometric symmetry, and are highly algebraic and spherical. Dendritic polymers have advantages such as high branching, good solubility, and low viscosity.

[0033] Hyperbranched polymers are a class of polymers with highly branched three-dimensional structures, exhibiting a certain relative molecular mass distribution and containing some linear structural units within their molecular structure, with a branching degree less than 1. Hyperbranched polymers are generally ellipsoidal in shape, with functional groups located at the ends of the polymer or on linear structural units within the molecule. Unlike dendritic polymers, although the structure of hyperbranched polymers is not as perfect, their synthesis is simpler and they possess similar physicochemical properties. Hyperbranched polymers can be obtained by polymerizing ABx-type multifunctional monomers (where A and B are mutually reactive functional groups, and the number of B groups X is 2 or more).

[0034] Highly branched polymers can be obtained commercially or in-house.

[0035] Preferably, the highly branched polymer is dendritic polyethyleneimine and / or hyperbranched polyamide-amine. Dendritic polyethyleneimine and / or hyperbranched polyamide-amine have a large number of end groups, and the end groups contain a large number of active functional groups amino (-NH2). When used simultaneously with organic amine solvents, they further promote the reaction with sulfur particles, thus having a synergistic effect.

[0036] Preferably, the dendritic polyethyleneimine has a weight-average molecular weight of 10,000 to 30,000. Preferably, the hyperbranched polyamide-amine has a weight-average molecular weight of 10,000 to 30,000. The dendritic polyethyleneimine can be prepared in-house or a commercially available product can be used; the hyperbranched polyamide-amine can also be prepared in-house or a commercially available product, such as the CYD-140A and CYD-150A products from Weihai Chenyuan Molecular New Materials Co., Ltd.

[0037] In this invention, the organic amine solvent is an organic solvent containing a nitrogen-containing group. Because the lone pair electrons on the nitrogen atom readily combine with protons, the organic amine solvent is alkaline. The nitrogen-containing group is selected from one or any combination of primary amine, secondary amine, tertiary amine, and quaternary ammonium groups. For example, the organic amine solvent is ethylenediamine, 2-hydroxyethylamine, diethylenetriamine, morpholine, pyrrole, formamide, acetamide, or benzamide.

[0038] Preferably, the nitrogen-containing group is a primary amino group. Compared to secondary amino, tertiary amino, and quaternary ammonium groups, primary amino groups have the strongest basicity and therefore exhibit stronger sulfur-dissolving properties.

[0039] Preferably, the organic amine solvent is selected from one or any combination of ethylenediamine, 2-hydroxyethylamine, and diethylenetriamine.

[0040] Preferably, the water-soluble sulfide salt is a water-soluble alkali metal sulfide and / or a water-soluble alkaline earth metal sulfide; the water-soluble hydrosulfide salt is a water-soluble alkali metal hydrosulfide and / or a water-soluble alkaline earth metal hydrosulfide.

[0041] Preferably, the water-soluble alkali metal sulfide is sodium sulfide and / or potassium sulfide. Preferably, the water-soluble alkali metal hydrosulfide is sodium hydrosulfide.

[0042] The technical solution adopted by the sulfur solvent of this invention is as follows:

[0043] A sulfur-dissolving agent, comprising water and the sulfur-dissolving composition as described above.

[0044] The sulfur solvent of this invention has high solubility for sulfur, and is safer and more environmentally friendly. It is not strongly irritating, has no foul odor, and is low in toxicity. It is not only non-corrosive, but also has a certain anti-corrosion effect.

[0045] Preferably, the mass ratio of the water to the sulfur-dissolving composition is (61.7–72.9):(27.1–38.3).

[0046] Preferably, the sulfur solvent is composed of the following components in mass percentage: 5% highly branched polymer, 0.1-0.3% amino-modified nanomaterials, 20-30% organic amine solvents, 2-3% inorganic base catalysts, and the balance being water; the amino-modified nanomaterials are amino-modified carbon nanotubes and / or amino-modified graphene oxide.

[0047] The technical solution for the application of the sulfur-dissolving composition or sulfur-dissolving agent of the present invention in the exploitation of sulfur-containing gas fields is as follows:

[0048] The application of the sulfur-dissolving composition or sulfur-dissolving agent as described above in the exploitation of sulfur-containing gas fields.

[0049] When the sulfur-dissolving composition or sulfur-dissolving agent of the present invention is applied in the exploitation of sulfur-containing gas fields, it has strong sulfur-dissolving ability, no strong irritation, no malodor, low toxicity, and is safer and more environmentally friendly. It is not only non-corrosive to the gathering and transportation system, but also has a certain anti-corrosion effect. It can achieve efficient and safer environmentally friendly sulfur-dissolving cleaning of sulfur-containing gas field production layers, wellbores, and surface gathering and transportation systems.

[0050] Preferably, the sulfur-dissolving agent described above is used as a cleaning agent for the surface gathering and transportation system of sulfur-containing gas fields. Detailed Implementation

[0051] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0052] The amino-modified carbon nanotubes used in the embodiments of this invention are prepared by a method comprising the following steps:

[0053] (1) A mixture of multi-walled carbon nanotubes (purity > 95%, diameter 40-60 nm, length 5-15 μm, purchased from Shenzhen Nanoport Co., Ltd.) in a mass ratio of 1:100:33, concentrated sulfuric acid and concentrated nitric acid was heated to 40°C and kept at that temperature for 3 h. The system after heating was washed with distilled water and then centrifuged with a high-speed centrifuge. The washing and centrifugation were repeated until the pH of the supernatant obtained from washing was close to 7. The solid obtained from centrifugation was then dried in an oven at 60°C for 8 h to obtain carboxylated carbon nanotubes.

[0054] (2) 0.1 g of carboxylated carbon nanotubes were dispersed in 60 mL of amine compound (ethylenediamine), and then 8 mg of HATU condensation reagent was added to the dispersion. The mixture was heated to 40 °C for amidation reaction for 4 h. Then, distilled water and the amidation reaction system were mixed and centrifuged. Finally, the solid obtained by centrifugation was dried in an oven at 60 °C for 8 h to obtain amino-modified carbon nanotubes (as shown in Formula 3).

[0055]

[0056] The amino-modified graphene oxide used in the embodiments of the present invention is prepared by a method comprising the following steps:

[0057] (1) Under stirring conditions, 1 part by mass of graphite powder was added to 25 parts by mass of concentrated sulfuric acid, and then 1 part by mass of sodium nitrate was added. The mixture was stirred for 1 hour, and then 3.7 parts by mass of KMnO4 was slowly added. The temperature was controlled to be less than 15°C and the mixture was stirred for 2 hours. Then the temperature of the reaction solution was raised to 30-40°C and the mixture was stirred for 1 hour. Then 35 parts by mass of distilled water was added and the temperature was raised to 90°C. The mixture was stirred for 30 minutes. Finally, the reaction was terminated by adding 55 parts by mass of distilled water and 8 parts by mass of 30% hydrogen peroxide to obtain a graphene oxide suspension. After ultrasonic treatment for 30 minutes, the suspension was filtered and washed several times with dilute hydrochloric acid and distilled water. The dark brown precipitate was dried at 40°C for 24 hours to obtain graphene oxide (GO).

[0058] (2) Graphene oxide (GO) was added to N,N-dimethylformamide (DMF) and sonicated for 2 h to obtain a graphene oxide suspension. Then, an amine compound (ethylenediamine) and N,N′-dicyclohexylcarboimide (DCC) were added to the graphene oxide suspension, and the suspension was sonicated for 20 min. The reaction system was then mixed and reacted at 60 °C for 6 h. Anhydrous ethanol was added to the reaction system, and the mixture was allowed to stand overnight. The supernatant was removed, the mixture was filtered, and the solid obtained from the filtration was washed with anhydrous ethanol and distilled water. The solid was then dried at 60 °C to obtain amino-modified graphene oxide (GO-NH2). The mass ratio of graphene oxide, DMF, amine compound, and DCC was 1:1000:150:25.

[0059] The dendritic polyethyleneimine used in the embodiments of the present invention has a weight-average molecular weight of 20,000 and was purchased from Aladdin Reagent Co., Ltd.

[0060] The hyperbranched polyamide-amine used in the embodiments of the present invention was purchased from Weihai Chenyuan Molecular New Materials Co., Ltd., and the product model is CYD-140A (molecular weight is 14215).

[0061] I. Specific embodiments of the sulfur-dissolving composition of the present invention are as follows:

[0062] Example 1

[0063] The sulfur-dissolving composition of this embodiment includes a highly branched polymer, amino-modified carbon nanotubes, an organic amine solvent, and an inorganic base catalyst; the highly branched polymer is dendritic polyethyleneimine, the organic amine solvent is ethylenediamine, and the inorganic base catalyst is a water-soluble hydrosulfide salt, specifically sodium hydrosulfide; the mass ratio of the highly branched polymer, amino-modified carbon nanotubes, organic amine solvent, and inorganic base catalyst is 5:0.1:20:3.

[0064] Example 2

[0065] The sulfur-dissolving composition of this embodiment includes a highly branched polymer, amino-modified carbon nanotubes, an organic amine solvent, and an inorganic base catalyst; the highly branched polymer is a hyperbranched polyamide-amine, the organic amine solvent is diethylenetriamine, and the inorganic base catalyst is a water-soluble sulfide salt, specifically sodium sulfide; the mass ratio of the highly branched polymer, amino-modified carbon nanotubes, organic amine solvent, and inorganic base catalyst is 5:0.1:20:2.

[0066] Example 3

[0067] The sulfur-dissolving composition of this embodiment includes a highly branched polymer, amino-modified graphene oxide, an organic amine solvent, and an inorganic base catalyst; the highly branched polymer is dendritic polyethyleneimine, the organic amine solvent is 2-hydroxyethylamine, and the inorganic base catalyst is a water-soluble sulfide salt, specifically potassium sulfide; the mass ratio of the highly branched polymer, amino-modified graphene oxide, organic amine solvent, and inorganic base catalyst is 5:0.2:30:3.

[0068] Example 4

[0069] The sulfur-dissolving composition of this embodiment includes a highly branched polymer, amino-modified carbon nanotubes, an organic amine solvent, and an inorganic base catalyst. The highly branched polymer is composed of dendritic polyethyleneimine and hyperbranched polyamide-amine, with a mass ratio of 3:2. The organic amine solvent is composed of ethylenediamine and diethylenetriamine, with a mass ratio of 2:1. The inorganic base catalyst is composed of water-soluble hydrosulfide and water-soluble sulfide, with a mass ratio of 2:1. The water-soluble hydrosulfide is sodium hydrosulfide, and the water-soluble sulfide is sodium sulfide. The mass ratio of the highly branched polymer, amino-modified carbon nanotubes, organic amine solvent, and inorganic base catalyst is 5:0.2:30:3.

[0070] Example 5

[0071] The sulfur-dissolving composition of this embodiment includes a highly branched polymer, amino-modified graphene oxide, an organic amine solvent, and an inorganic base catalyst; the highly branched polymer is a hyperbranched polyamide-amine; the organic amine solvent is composed of ethylenediamine and 2-hydroxyethylamine, with a mass ratio of ethylenediamine to 2-hydroxyethylamine of 1:2; the inorganic base catalyst is a water-soluble sulfide salt, specifically sodium sulfide; and the mass ratio of the highly branched polymer, amino-modified graphene oxide, organic amine solvent, and inorganic base catalyst is 5:0.3:30:3.

[0072] Example 6

[0073] The sulfur-dissolving composition of this embodiment includes a highly branched polymer, amino-modified carbon nanotubes, an organic amine solvent, and an inorganic base catalyst; the highly branched polymer is dendritic polyethyleneimine; the organic amine solvent is composed of 2-hydroxyethylamine and diethylenetriamine, with a mass ratio of 1:1; the inorganic base catalyst is a water-soluble hydrosulfide salt, specifically sodium hydrosulfide; and the mass ratio of the highly branched polymer, amino-modified carbon nanotubes, organic amine solvent, and inorganic base catalyst is 5:0.3:20:3.

[0074] Example 7

[0075] The sulfur-dissolving composition of this embodiment includes a highly branched polymer, amino-modified carbon nanotubes and amino-modified graphene oxide, an organic amine solvent and an inorganic base catalyst; the mass ratio of amino-modified carbon nanotubes and amino-modified graphene oxide is 1:1; the highly branched polymer is dendritic polyethyleneimine; the organic amine solvent is composed of ethylenediamine and diethylenetriamine, with a mass ratio of ethylenediamine to diethylenetriamine of 1:1; the inorganic base catalyst is a water-soluble sulfide salt, which is composed of sodium sulfide and potassium sulfide, with a mass ratio of sodium sulfide to potassium sulfide of 2:1; the mass ratio of the highly branched polymer, amino-modified carbon nanotubes and amino-modified graphene oxide, organic amine solvent and inorganic base catalyst is 5:0.1:0.1:20:3.

[0076] II. Specific embodiments of the sulfur solvent of the present invention are as follows:

[0077] Example 8

[0078] The sulfur dissolving agent in this embodiment is composed of water and the sulfur dissolving composition of Example 1, with a mass ratio of water to sulfur dissolving composition of 71.9:28.1.

[0079] Example 9

[0080] The sulfur dissolving agent in this embodiment is composed of water and the sulfur dissolving composition of Example 2, with a mass ratio of water to sulfur dissolving composition of 72.9:27.1.

[0081] Example 10

[0082] The sulfur dissolving agent in this embodiment is composed of water and the sulfur dissolving composition of Example 3, with a mass ratio of water to sulfur dissolving composition of 61.8:38.2.

[0083] Example 11

[0084] The sulfur dissolving agent in this embodiment consists of water and the sulfur dissolving composition of Example 4, with a mass ratio of water to sulfur dissolving composition of 61.8:38.2.

[0085] Example 12

[0086] The sulfur dissolving agent in this embodiment is composed of water and the sulfur dissolving composition of Example 5, with a mass ratio of water to sulfur dissolving composition of 61.7:38.3.

[0087] Example 13

[0088] The sulfur dissolving agent in this embodiment is composed of water and the sulfur dissolving composition of Example 6, with a mass ratio of water to sulfur dissolving composition of 71.7:28.3.

[0089] Example 14

[0090] The sulfur dissolving agent in this embodiment is composed of water and the sulfur dissolving composition of Example 7, with a mass ratio of water to sulfur dissolving composition of 71.8:28.2.

[0091] The mass fractions of each component in the sulfur solvents of Examples 8-14 are shown in Table 1.

[0092] Table 1. Mass fraction of each component in the sulfur solvent of Examples 8-14

[0093]

[0094]

[0095] Comparative Example 1

[0096] The sulfur solvent in this comparative example is a primary amine sulfur solvent, which is Example 4 in Chinese Patent Document CN108084980A. It is prepared by a method including the following steps: 20g of tert-butylamine and 75g of DMSO are added to a reaction vessel at room temperature, followed by the addition of 1g of triethylenetetramine, and the mixture is stirred thoroughly. Then, 10g of diethanolamine is added, and the mixture is stirred until homogeneous to obtain the sulfur solvent.

[0097] Comparative Example 2

[0098] The sulfur solvent in this comparative example is Example 1 from Chinese Patent Document CN110964492A, which is made from 100 parts by weight of PAMAM-(NH2)8, 15 parts by weight of N,N-dimethylacetamide and 0.1 parts by weight of sodium hydrosulfide; PAMAM-(NH2)8 has a weight-average molecular weight of 1430, a degree of branching of 1, and a terminal amino content of 100%.

[0099] Comparative Example 3

[0100] The sulfur solvent in this comparative example is Example 3 from Chinese Patent Document CN102408886B, which is prepared by a method including the following steps: dissolving sodium hydroxide (8g) in water (20g), and after the sodium hydroxide is completely dissolved, adding sulfolane (0.5g), N-methylpyrrolidone (1.5g), and N,N-dimethylformamide (0.5g) in sequence to obtain the sulfur solvent.

[0101] III. Specific embodiments of the application of the sulfur-dissolving agent of the present invention as a cleaning agent for surface gathering and transportation systems in sulfur-containing gas fields are as follows:

[0102] Any of the sulfur-dissolving agents in Examples 8-14 can be used as cleaning agents for the surface gathering and transportation systems of sulfur-containing gas fields.

[0103] Experimental Example 1

[0104] The sulfur dissolving agents of Examples 8-14 and Comparative Examples 1-3 were subjected to sulfur dissolving experiments at room temperature. The specific method of the sulfur dissolving experiment is as follows: a mass of sulfur dissolving agent m was poured into a round-bottom flask, and then the round-bottom flask was moved to a constant temperature water bath at 40°C. Sulfur powder with a mass of m0 was added to the round-bottom flask. After stirring at constant temperature for 60 minutes, the mixture was filtered. The mass of the filter paper was m1, and the filter paper was rinsed with tetrahydrofuran. The liquid on the filter paper was dried at 80°C until the mass was constant at m2. The amount of sulfur dissolved corresponding to 1g of sulfur dissolving agent was calculated using formula (1) and recorded as S.

[0105]

[0106] The amount of sulfur dissolved, S, in the sulfur solvents of Examples 8-14 and Comparative Examples 1-3 is shown in Table 2.

[0107] Table 2. Sulfur dissolution amount S of the sulfur solvents in Examples 8-14 and Comparative Examples 1-3

[0108] Sulfur solvent Dissolved sulfur content S Example 8 2.41 Example 9 2.36 Example 10 2.19 Example 11 2.22 Example 12 2.07 Example 13 2.17 Example 14 2.32 Comparative Example 1 0.918 Comparative Example 2 0.942 Comparative Example 3 1.15

[0109] The results show that the sulfur solvents in Examples 8-14 can simultaneously meet the requirements of high sulfur dissolving capacity, low toxicity and irritation, and environmental friendliness, and do not contain substances that are toxic or harmful to humans and the environment, thus posing a low safety risk. The sulfur solvent in Comparative Example 1 has low sulfur dissolving efficiency and a high content of dimethyl sulfoxide in the system, resulting in a high safety risk; in addition, the sulfur solvents in Comparative Examples 2-3 also have poor sulfur dissolving capacity.

[0110] When the amount of amino-modified nanomaterial added to the sulfur-dissolving composition of the present invention is adjusted to 0, the amount of sulfur dissolved is significantly reduced (reduction rate of 51.7-58.5%) when the amine compound used to prepare amino-modified carbon nanotubes or amino-modified graphene oxide is replaced by hexamethylenediamine or decanediamine, and the prepared amino-modified carbon nanotubes or amino-modified graphene oxide is then used to prepare the sulfur-dissolving composition or sulfur-dissolving agent, the amount of sulfur dissolved is consistent with the amount of sulfur dissolved in the sulfur-dissolving composition or sulfur-dissolving agent prepared using amino-modified carbon nanotubes or amino-modified graphene oxide prepared by ethylenediamine.

[0111] Experiment Example 2

[0112] According to the methods in SY / T 5273-2014 "Performance Indicators and Evaluation Methods for Corrosion Inhibitors Used in Oilfield Produced Water Treatment", the corrosion resistance (static corrosion inhibition rate under normal pressure) of the sulfur solvents in Examples 8-14 and Comparative Examples 1-3 was tested, and the test results are shown in Table 3.

[0113] Table 3 shows the corrosion resistance of the sulfur solvents in Examples 8-14 and Comparative Examples 1-3.

[0114]

[0115]

[0116] The results show that the static corrosion inhibition rate of the sulfur solvents in Examples 8-14 all meet the requirement of corrosion inhibition rate > 72% in SY / T 5273-2014. Therefore, the sulfur solvent composition or sulfur solvent prepared in this invention has a certain anti-corrosion effect on the gathering and transportation system.

Claims

1. A sulfur-dissolving composition, characterized in that, This includes highly branched polymers, amino-modified nanomaterials, organic amine solvents, and inorganic base catalysts; The highly branched polymer has at least three amino groups at the ends of its molecular chains; the highly branched polymer is dendritic polyethyleneimine and / or hyperbranched polyamide-amine. The amino-modified nanomaterial is a nanomaterial with amino groups bonded to its surface; the nanomaterial is a carbon nanomaterial; the amino-modified nanomaterial is amino-modified carbon nanotube and / or amino-modified graphene oxide; wherein, the amino-modified carbon nanotube is prepared by an amidation reaction of an amine compound and a carboxylated carbon nanotube; the amino-modified graphene oxide is prepared by a condensation reaction of an amino group in an amine compound and a carboxyl group in graphene oxide; the amine compound has at least two amino groups. The inorganic base catalyst is a water-soluble sulfide salt and / or a water-soluble hydrosulfide salt; The mass ratio of the highly branched polymer, amino-modified nanomaterials, organic amine solvents and inorganic base catalysts is 5:(0.1~0.3):(20~30):(2~3).

2. The sulfur-dissolving composition according to claim 1, characterized in that, The carboxylated carbon nanotubes are prepared by a method comprising the following steps: heating a mixture of carbon nanotubes, concentrated sulfuric acid, and concentrated nitric acid, then performing solid-liquid separation on the heated system, and then removing acidic compounds and water from the solid obtained from the solid-liquid separation to obtain carboxylated carbon nanotubes; the mass ratio of carbon nanotubes, concentrated sulfuric acid, and concentrated nitric acid is 1:100:33; the temperature of the heating treatment is 30~50℃. The condensation reaction method includes the following steps: heating graphene oxide, amine compounds and dehydrating condensing agents in a solvent to 55~65℃ and mixing and reacting for 5~7 hours.

3. The sulfur-dissolving composition according to claim 1, characterized in that, The amine compounds used to prepare amino-modified carbon nanotubes; the amine compounds used to prepare amino-modified graphene oxide are independently selected from one or any combination of ethylenediamine, hexamethylenediamine, and decanediamine.

4. The sulfur-dissolving composition according to claim 1, characterized in that, The dendritic polyethyleneimine has a weight-average molecular weight of 10,000 to 30,000; the hyperbranched polyamide-amine has a weight-average molecular weight of 10,000 to 30,000.

5. The sulfur-dissolving composition according to claim 1, characterized in that, The organic amine solvent is selected from one or any combination of ethylenediamine, 2-hydroxyethylamine, and diethylenetriamine.

6. A sulfur solvent, characterized in that, It consists of water and a sulfur-dissolving composition as described in any one of claims 1-5.

7. The application of the sulfur-dissolving composition as described in any one of claims 1-5 or the sulfur-dissolving agent as described in claim 6 in the exploitation of sulfur-containing gas fields.

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