Low-temperature oil well desulfurizer and synthesis method thereof

Abstract

The invention belongs to the technical field of oil exploitation, and particularly relates to a low-temperature oil well desulfurizer and a synthesis method thereof. The method comprises the step of carrying out reductive amination reaction on 1-methyl piperazine-3-ketone and 1-amino-4-(2-ethoxyl) piperazine under the action of a catalyst in the presence of a weakly acidic organic solvent. On the basis of 1 mole part of 1-methyl piperazine-3-ketone, the dosage of the 1-amino-4-(2-ethoxyl) piperazine is 0.8 to 1.2 mole parts. The desulfurizer disclosed by the invention has the characteristics of wide raw material source, simple synthesis process and clean and pollution-free process; meanwhile, the desulfurizer has the characteristics of good desulfurization effect, high desulfurization speed and high sulfur capacity, and the sulfur capacity reaches 30% or above.

Description

Technical Field

[0001] The invention belongs to the technical field of petroleum exploitation, and in particular relates to a low-temperature oil well desulfurizer and a synthesis method thereof. Background Art

[0002] Hydrogen sulfide is one of the basic components present in crude oil, which has a great impact on crude oil extraction, transportation and application. For example, crude oil will produce hydrogen sulfide when it is decomposed by microorganisms underground, and organic sulfur in crude oil will also produce hydrogen sulfide after high temperature or water thermal cracking. Crude oil contains a small amount of water during the extraction process. Hydrogen sulfide dissolved in it will synergistically corrode steel, shorten the service life of pipelines and storage tanks, and even cause oil pipeline leakage. In addition, the escape of hydrogen sulfide during transportation will not only cause danger to workers, but also lead to catalyst poisoning in subsequent crude oil processing equipment. For this reason, it is required that hydrogen sulfide in crude oil must be removed to below a safe concentration before storage and transportation.

[0003] The conventional method of removing hydrogen sulfide from crude oil is deep flash evaporation, but after deep flash evaporation, 100-150 mg / L of dissolved hydrogen sulfide will still remain in the crude oil, which cannot achieve the purpose of completely removing hydrogen sulfide. It is very necessary to use an effective chemical hydrogen sulfide remover to completely eliminate the dissolved hydrogen sulfide in crude oil. After research and comparative analysis of crude oil chemical hydrogen sulfide removers, it is found that the use of water-soluble hydrogen sulfide removers to remove hydrogen sulfide from crude oil is the most effective. Crude oil exists in different states at different stages in the oilfield system, and the requirements for hydrogen sulfide removers are also different. The dehydrated crude oil is required to have a total water content of less than 0.5%, and usually the water content is lower than this value, with about 0.2% of the dissolution space. This requires that the desulfurization capacity of the crude oil chemical hydrogen sulfide remover should be high, the agent should have good permeability and mutual solubility, and react quickly and fully.

[0004] CN 107459998 A A mixed triazine-based crude oil desulfurizer. The invention belongs to the technical field of crude oil desulfurization in the petroleum industry. A mixed triazine-based crude oil desulfurizer, using water as a solvent, the mass concentrations of the solutes in the solution are: 1,3,5-tris (hydroxyethyl)-hexahydro-s-triazine is 5% to 80%, 1,3-hydroxyethyl-5-aminoethyl-triazine is 5% to 80%, 1,3-hydroxyethyl-5-methyl-triazine is 5% to 80%, 1-hydroxyethyl-3,5-di (methyl)-triazine is 5% to 80%, and 1,3,5-tris (methyl)-hexahydro-s-triazine is 5% to 80%. Preparation method of mixed triazine-based hydrogen sulfide removal agent: under the conditions of 25°C to 60°C and stirring speed ≤100 (r / min), the various solutes described above are added to 1000g of water separately or simultaneously in no particular order within 10 to 30 minutes. The invention has the characteristics of simple preparation process, high desulfurization activity of working solution, large sulfur capacity, instant desulfurization, irreversible desulfurization reaction, strong adaptability, and wide spectrum of application. However, the triazine of the invention has poor water solubility. At present, various co-solvents are generally added at home and abroad to improve its water solubility. Conventional mutual solvents include small molecule alcohols and ethers. However, the addition of these co-solvents affects the sulfur capacity of the desulfurizer, and also reduces the absorption rate of the desulfurizer to oil and gas hydrogen sulfide.

[0005] CN 105056710 B discloses a liquid absorbent for removing hydrogen sulfide from oil and gas, which comprises two types of substances, one type is hexahydrotriazine compounds, and the other type is oxazolidine compounds, both of which have an absorption effect on hydrogen sulfide, and after the two are mixed in a certain proportion, not only a uniform phase is presented, but also excellent water solubility, and the absorption rate and efficiency are improved to a certain extent compared with existing products. The hydrogen sulfide absorbent can be used to reduce the corrosion of hydrogen sulfide to metal equipment and pipelines, protect workers from hydrogen sulfide gas damage, and prevent hydrogen sulfide from polluting the atmospheric environment. However, the synthesis process of the oxazolidine synthesis method in the patent is difficult to control in actual operation, and the synthetic product is a mixture of oxazolidine and by-products, with poor repeatability, and there are potential safety hazards in this synthesis process, and it is difficult to industrialize this technology.

[0006] CN109593545A discloses a composite desulfurizer suitable for oil wells with high oil content and a preparation method thereof. The desulfurizer is composed of 20-27.5% formaldehyde by mass fraction, 20-27.5% ethanolamine, 2-7% surfactant, 1-5% small molecule alcohol and the remainder of water. The desulfurizer has low viscosity and is fully in contact with crude oil, has good mutual solubility effect, high antifreeze performance, short reaction time and is easy to prepare. The desulfurizer achieves the effect by reacting the reaction product of aldehyde and alcoholamine compounds with hydrogen sulfide. The surfactant has an emulsifying effect, so that the crude oil and the desulfurizer have a good mutual solubility effect. The small molecule alcohol is used as an antifreeze liquid, so that the desulfurizer can still be used in a sub-zero environment. The desulfurization efficiency of the desulfurizer is above 98%, and the reaction product is easy to be subsequently treated to prevent the generation of ferrous sulfide deposition, which does not affect the normal operation of oil production operations. However, the desulfurization principle of this patent is only the simple absorption of hydrogen sulfide by ethanolamine, the action principle is single, and the desulfurization effect is limited. Summary of the invention

[0007] The present invention aims to provide a low-temperature oil well desulfurizer and a synthesis method thereof in view of the above-mentioned deficiencies of the prior art. The desulfurizer of the present invention has the characteristics of wide raw material sources, simple synthesis process, clean process and no pollution; at the same time, the desulfurizer has the characteristics of good desulfurization effect, fast desulfurization and high sulfur capacity, and the sulfur capacity reaches more than 30%.

[0008] Therefore, in order to achieve the above-mentioned purpose, on the one hand, the present invention discloses a low-temperature oil well desulfurization agent, and the molecular structure of the desulfurization agent is as follows:

[0009]

[0010] On the other hand, the present invention provides a method for synthesizing a low-temperature oil well desulfurization agent, the method comprising: under the action of a catalyst and in the presence of a weakly acidic organic solvent, 1-methylpiperazine-3-one and 1-amino-4-(2-hydroxyethyl)piperazine undergo a reductive amination reaction.

[0011] The third object of the present invention is to disclose the application of the above desulfurizing agent in desulfurization of oil wells with high hydrogen sulfide content.

[0012] The low-temperature oil well desulfurizer of the present invention belongs to a polyazine desulfurizer, and the desulfurization principle is as follows:

[0013] (1) The aqueous solution of the present invention is alkaline and has a certain adsorption effect on hydrogen sulfide;

[0014] (2) The four nitrogen atoms in the oxazine ring of the molecule can undergo substitution reactions with sulfur to completely remove hydrogen sulfide;

[0015] (3) The amine-containing compounds generated after the nitrogen atom substitution reaction on the oxazine ring also have desulfurization ability;

[0016] (4) The molecule of the present invention contains multiple tertiary amines and secondary amines, which are weakly alkaline and can adsorb hydrogen sulfide;

[0017] (5) The present invention belongs to polar molecules and has a certain dissolving effect on polar molecule hydrogen sulfide according to the principle of like dissolves like;

[0018] (6) The molecule of the present invention is linear and has little steric hindrance in absorbing hydrogen sulfide.

[0019] Compared with the prior art, the present invention has the following beneficial effects and advantages:

[0020] (1) The low-temperature oil well desulfurizer of the present invention has the characteristics of wide raw material sources, simple synthesis process, clean process and no pollution;

[0021] (2) The low-temperature oil well desulfurizer of the present invention has the characteristics of good desulfurization effect, rapid desulfurization and high sulfur capacity, and the sulfur capacity reaches more than 30%. DETAILED DESCRIPTION

[0022] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0023] According to a first aspect of the present invention, the present invention discloses a low-temperature oil well desulfurization agent, the molecular structure of the desulfurization agent is as follows:

[0024]

[0025] In a second aspect, the present invention provides a method for synthesizing a low-temperature oil well desulfurization agent, the method comprising: in the presence of a weakly acidic organic solvent and under the action of a catalyst, 1-methylpiperazine-3-one and 1-amino-4-(2-hydroxyethyl)piperazine undergo a reductive amination reaction.

[0026] In the present invention, preferably, based on 1 mol part of 1-methylpiperazine-3-one, the amount of 1-amino-4-(2-hydroxyethyl)piperazine used is 0.8-1.2 mol parts.

[0027] More preferably, based on 1 mol of 1-methylpiperazine-3-one, the amount of 1-amino-4-(2-hydroxyethyl)piperazine used is 0.9-1.1.

[0028] In the present invention, preferably, the reductive amination reaction temperature is room temperature-60°C, and the time is 60-120 min.

[0029] More preferably, the reductive amination reaction comprises two stages carried out sequentially, the reaction temperature of the first stage is room temperature and the reaction time is 30-60 min; the reaction temperature of the second stage is 50-60° C. and the reaction time is 30-60 min.

[0030] In the present invention, preferably, the catalyst is one of sodium borocyanide, sodium cyanoborohydride, and sodium triacetate borocyanide.

[0031] More preferably, the catalyst is sodium cyanoborohydride or sodium triacetate borohydride.

[0032] In the present invention, preferably, based on 1 mol part of 1-methylpiperazine-3-one, the amount of the catalyst used is 0.9-1.3 mol parts.

[0033] More preferably, the catalyst is used in an amount of 1-1.2 parts by mole based on 1 part by mole of 1-methylpiperazine-3-one.

[0034] In the present invention, preferably, the weak acidity refers to pH 3-4.

[0035] In the present invention, preferably, the organic solvent is one of isopropanol, ethanol and methanol.

[0036] According to a more specific preferred embodiment, the synthesis method of the low-temperature oil well desulfurization agent has the following specific steps:

[0037] (1) 1-methylpiperazine-3-one, an organic solvent, and a catalyst were sequentially added to a reactor in a four-necked flask, and the pH was adjusted to 3-4 with hydrochloric acid;

[0038] (2) dissolving 1-amino-4-(2-hydroxyethyl)piperazine in an organic solvent of the same weight as in step (1), placing the solution in a dropping funnel, and slowly dropping the solution into a four-necked flask while stirring. After the dropping is complete, continuing the reaction for 30-60 minutes, heating the solution to 50-60° C., and reacting the solution for 30-60 minutes;

[0039] (3) The mixed solution is distilled under reduced pressure to 60°C until there is no distillate, hydrochloric acid is added, and the mixture is filtered. The filtrate is cooled to below 5°C to precipitate a solid, which is filtered. The solid is dissolved with sodium hydroxide, and the pH of the solution is controlled at 8-9 to obtain a desulfurizing agent.

[0040] Preferably, the weight ratio of the organic solvent to 1-methylpiperazine-3-one in step (1) is 4-6:1.

[0041] Preferably, based on 1 mol of 1-methylpiperazine-3-one, the amount of hydrochloric acid used in step (3) is 1.9-2.1 mol.

[0042] The reaction equation for the synthesis of the low-temperature oil well desulfurization agent of the present invention is as follows:

[0043]

[0044] The third object of the present invention is to disclose the application of the above desulfurizer in desulfurization of oil wells with high hydrogen sulfide content. There is no special requirement for the specific application, and it can be a conventional application in the field, which will not be discussed in detail here.

[0045] More preferably, the hydrogen sulfide content of the high hydrogen sulfide oil well is less than 100000 mg / m 3 , the oil well temperature is below 80℃.

[0046] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0047] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

[0048] The present invention will be further described below with reference to specific embodiments.

[0049] In the present invention, the devices or equipment used are all conventional devices or equipment known in the art and are commercially available.

[0050] In the following examples and comparative examples, unless otherwise specified, all reagents used were commercially available chemically pure reagents.

[0051] Example 1

[0052] (1) 0.1 mol 1-methylpiperazine-3-one, 45.6 g isopropanol, and 0.09 mol sodium borohydride were added to a four-necked flask reactor in sequence, and the pH was adjusted to 3-4 with 1 mol / L hydrochloric acid;

[0053] (2) Dissolve 0.12 mol of 1-amino-4-(2-hydroxyethyl)piperazine in 45.6 g of isopropanol, place in a dropping funnel, and slowly drip into a four-necked flask while stirring. After the dripping is complete, react for 30 minutes, heat to 60° C., and react for 40 minutes;

[0054] (3) The mixed solution is distilled under reduced pressure to 60°C until there is no distillate, 0.19mol1mol / L hydrochloric acid is added, filtered, the filtrate is cooled to below 5°C, a solid is precipitated, filtered, and the solid is dissolved with 2mol / L sodium hydroxide, and the pH of the solution is controlled at 8-9, thereby obtaining a low-temperature oil well desulfurization agent product.

[0055] Example 2

[0056] (1) 0.1 mol 1-methylpiperazine-3-one, 52.8 g ethanol, and 0.13 mol sodium cyanoborohydride were added to a four-necked flask reactor in sequence, and the pH was adjusted to 3-4 with 1 mol / L hydrochloric acid;

[0057] (2) Dissolve 0.08 mol of 1-amino-4-(2-hydroxyethyl)piperazine in 52.8 g of ethanol, place in a dropping funnel, and slowly drip into a four-necked flask while stirring. After the dripping is complete, react for 40 minutes, heat to 50° C., and react for 40 minutes;

[0058] (3) The mixed solution is distilled under reduced pressure to 60°C until there is no distillate, 0.21mol1mol / L hydrochloric acid is added, filtered, the filtrate is cooled to below 5°C, a solid is precipitated, filtered, and the solid is dissolved with 2mol / L sodium hydroxide, and the pH of the solution is controlled at 8-9, thereby obtaining a low-temperature oil well desulfurization agent product.

[0059] Example 3

[0060] (1) 0.1 mol 1-methylpiperazine-3-one, 68.4 g isopropanol, and 0.1 mol sodium borohydride triacetate were added to a four-necked flask reactor in sequence, and the pH was adjusted to 3-4 with 1 mol / L hydrochloric acid;

[0061] (2) Dissolve 0.09 mol of 1-amino-4-(2-hydroxyethyl)piperazine in 68.4 g of isopropanol, place in a dropping funnel, and slowly drip into a four-necked flask while stirring. After the dripping is complete, react for 60 minutes, heat to 55° C., and react for 40 minutes;

[0062] (3) The mixed solution is distilled under reduced pressure to 60°C until there is no distillate, 0.2 mol / L hydrochloric acid is added, filtered, the filtrate is cooled to below 5°C, a solid is precipitated, filtered, and the solid is dissolved with 2 mol / L sodium hydroxide, and the pH of the solution is controlled at 8-9, thereby obtaining a low-temperature oil well desulfurization agent.

[0063] Example 4

[0064] (1) 0.1 mol 1-methylpiperazine-3-one, 53.6 g methanol, and 0.12 mol sodium borohydride were added to a four-necked flask reactor in sequence, and the pH was adjusted to 3-4 with 1 mol / L hydrochloric acid;

[0065] (2) Dissolve 0.1 mol of 1-amino-4-(2-hydroxyethyl)piperazine in 53.6 g of methanol, place in a dropping funnel, and slowly drip into a four-necked flask while stirring. After the dripping is complete, react for 30 minutes, heat to 60° C., and react for 60 minutes;

[0066] (3) The mixed solution is distilled under reduced pressure to 60°C until there is no distillate, 0.205mol1mol / L hydrochloric acid is added, filtered, the filtrate is cooled to below 5°C, a solid is precipitated, filtered, and the solid is dissolved with 2mol / L sodium hydroxide, and the pH of the solution is controlled at 8-9, thereby obtaining a low-temperature oil well desulfurization agent product.

[0067] Example 5

[0068] (1) 0.1 mol 1-methylpiperazine-3-one, 54.8 g ethanol, and 0.11 mol sodium cyanoborohydride were added to a four-necked flask reactor in sequence, and the pH was adjusted to 3-4 with 1 mol / L hydrochloric acid;

[0069] (2) Dissolve 0.11 mol of 1-amino-4-(2-hydroxyethyl)piperazine in 54.8 g of ethanol, place in a dropping funnel, and slowly drip into a four-necked flask while stirring. After the dripping is complete, react for 50 min, heat to 52° C., and react for 30 min.

[0070] (3) The mixed solution is distilled under reduced pressure to 60°C until there is no distillate, 0.2 mol / L hydrochloric acid is added, filtered, the filtrate is cooled to below 5°C, a solid is precipitated, filtered, and the solid is dissolved with 2 mol / L sodium hydroxide, and the pH of the solution is controlled at 8-9, thereby obtaining a low-temperature oil well desulfurization agent.

[0071] Example 6

[0072] (1) 0.1 mol 1-methylpiperazine-3-one, 62.4 g methanol, and 0.11 mol sodium borohydride triacetate were added to a four-necked flask reactor in sequence, and the pH was adjusted to 3-4 with 1 mol / L hydrochloric acid;

[0073] (2) Dissolve 0.1 mol of 1-amino-4-(2-hydroxyethyl)piperazine in 62.4 g of methanol, place in a dropping funnel, and slowly drip into a four-necked flask while stirring. After the dripping is complete, react for 40 minutes, heat to 58° C., and react for 45 minutes;

[0074] (3) The mixed solution is distilled under reduced pressure to 60°C until there is no distillate, 0.195mol1mol / L hydrochloric acid is added, filtered, the filtrate is cooled to below 5°C, a solid is precipitated, filtered, and the solid is dissolved with 2mol / L sodium hydroxide, and the pH of the solution is controlled at 8-9, thereby obtaining a low-temperature oil well desulfurization agent product.

[0075] Example 7 Sulfur Capacity Test

[0076] Sulfur capacity is one of the most important indicators for evaluating the performance of a desulfurizer. The sulfur capacity of the present invention is tested according to the following steps. The triazine desulfurizer of Dongying Jiushicheng Petroleum Technology Co., Ltd. is used as comparative example 1, and the triazine desulfurizer of Shengli Oilfield Jindao Petroleum Engineering Technology Co., Ltd. is used as comparative example 2. The test results are shown in Table 1.

[0077] (1) Absorption of hydrogen sulfide

[0078] The device is connected in a fume hood. Weigh 10g of the desulfurizer to be tested, add it to the hydrogen sulfide absorption reaction bottle, add 400g of distilled water, put in the sintered filter element so that it is close to the bottom (3-5mm) of the absorption reaction bottle, and connect it to the outlet of the hydrogen sulfide cylinder through a pipeline, so that the filter element is completely immersed in the liquid, and the top of the filter element is 15mm below the liquid level of the desulfurizer dilution liquid. Add a rubber stopper to the upper part of the absorption tube, leaving a gas outlet, which is connected to the silver nitrate solution and the sodium hydroxide solution in turn. Weigh the mass of the hydrogen sulfide absorption reaction bottle and the sintered filter element, which is m0.

[0079] Place the hydrogen sulfide absorption reaction bottle in a constant temperature water bath at 60℃±1℃, and make the liquid level of the water bath higher than the level of the desulfurizer dilution liquid by more than 20mm. After keeping the constant temperature for at least 15 minutes, start injecting hydrogen sulfide or hydrogen sulfide gas balanced by inert gas into the absorption tube, and control the gas injection speed to no more than 20mL / min through the flow meter. Weigh the mass of the hydrogen sulfide absorption reaction bottle (including the desulfurizer, distilled water and filter element) every 30 minutes until the mass of the absorption reaction bottle does not increase, recorded as m1.

[0080] At the same time, the mass of the absorption reaction bottle (including distilled water and filter element) n0 and n1 before and after the reaction was measured when only 400g of distilled water was added without adding desulfurizer.

[0081] (2) Calculation of sulfur capacity

[0082] The sulfur capacity is calculated according to formula (1):

[0083]

[0084] Where:

[0085] X——sulfur content of desulfurizer, %;

[0086] m0——weight of the absorption reaction bottle before the experiment (including desulfurizer, distilled water and filter element), g;

[0087] m1——mass of the absorption reaction bottle after the experiment (including desulfurizer, distilled water and filter element), g;

[0088] m——mass of the desulfurizer to be tested, g;

[0089] n0——the mass of the absorption reaction bottle before the experiment (including distilled water and filter element), g;

[0090] n1——The mass of the absorption reaction bottle after the experiment (including distilled water and filter element), g.

[0091] Table 1 Desulfurizer sulfur capacity test results

[0092] Desulfurization agent Sulfur capacity R, % Example 1 31.3 Example 2 34.6 Example 3 35.3 Example 4 33.3 Example 5 36.8 Example 6 38.9 Comparative Example 1 20.2 Comparative Example 2 23.1

[0093] It can be seen from Table 1 that the sulfur capacity R of the low-temperature oil well desulfurizer of the present invention (Implementation 1-6) is greater than 30%, and the highest is 38.9% (Implementation 6), while the sulfur capacity R of the triazine desulfurizer of Comparative Example 1 Dongying Jiushicheng Petroleum Technology Co., Ltd. and the triazine desulfurizer of Comparative Example 2 Shengli Oilfield Jindao Petroleum Engineering Technology Co., Ltd. are 20.2% and 23.1%, respectively, which are significantly lower than the desulfurizer of the present invention.

[0094] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for synthesizing a low-temperature oil well desulfurization agent, characterized in that: The synthesis method comprises: under the action of a catalyst and in the presence of a weakly acidic organic solvent, 1-methylpiperazine-3-one and 1-amino-4-(2-hydroxyethyl)piperazine undergo a reductive amination reaction; The amount of 1-amino-4-(2-hydroxyethyl)piperazine used is 0.8-1.2 parts by mole based on 1 part by mole of 1-methylpiperazin-3-one.

2. The method for synthesizing a low-temperature oil well desulfurization agent according to claim 1, characterized in that: Based on 1 mol of 1-methylpiperazine-3-one, the amount of 1-amino-4-(2-hydroxyethyl)piperazine used is 0.9-1.

1.

3. The method for synthesizing a low-temperature oil well desulfurization agent as claimed in claim 1, characterized in that: The reductive amination reaction temperature is room temperature-60°C, and the reaction time is 60-120 minutes.

4. A method for synthesizing a low-temperature oil well desulfurization agent as claimed in claim 3, characterized in that: The reductive amination reaction includes two stages that are carried out sequentially. The reaction temperature of the first stage is room temperature and the reaction time is 30-60 minutes; the reaction temperature of the second stage is 50-60° C. and the reaction time is 30-60 minutes.

5. The method for synthesizing a low-temperature oil well desulfurization agent as claimed in claim 1, characterized in that: The catalyst is one of sodium borocyanide, sodium cyanoborohydride and sodium triacetate borocyanide.

6. The method for synthesizing a low-temperature oil well desulfurization agent as claimed in claim 1, characterized in that: The catalyst is sodium cyanoborohydride or sodium triacetate borohydride.

7. A method for synthesizing a low-temperature oil well desulfurization agent as claimed in claim 5 or 6, characterized in that: The catalyst is used in an amount of 0.9-1.3 parts by mole based on 1 part by mole of 1-methylpiperazine-3-one.

8. A method for synthesizing a low-temperature oil well desulfurization agent as claimed in claim 7, characterized in that: The catalyst is used in an amount of 1 to 1.2 parts by mole based on 1 part by mole of 1-methylpiperazine-3-one.

9. The method for synthesizing a low-temperature oil well desulfurization agent as claimed in claim 1, characterized in that: The weak acidity refers to pH 3-4.

10. The method for synthesizing a low-temperature oil well desulfurization agent according to claim 1, characterized in that: The organic solvent is one of isopropanol, ethanol and methanol.

11. A low-temperature oil well desulfurization agent, characterized in that: The molecular structural formula of the desulfurizer is as follows:

12. Use of the low-temperature oil well desulfurization agent as claimed in claim 11 in desulfurization of oil wells with high hydrogen sulfide content.

13. The use of a low-temperature oil well desulfurization agent in desulfurization of oil wells with high hydrogen sulfide content as claimed in claim 12, characterized in that: The hydrogen sulfide content of the oil well in the application is less than 100000 mg / m 3 , the oil well temperature is below 80℃.

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