Desulfurizing agent for oil field and preparation method thereof

Abstract

The invention belongs to the technical field of petrochemical engineering, and particularly relates to a desulfurizer for an oil field and a preparation method thereof. The preparation method comprises the following steps: carrying out substitution reaction on 1, 4-bis (3-aminopropyl) piperazine and epoxy bromopropane in an alkaline ethanol solution; a substitution reaction product is subjected to a ring-opening reaction in a weak acid environment. Based on 1 mole part of the 1, 4-bis (3-aminopropyl) piperazine, the mole part of the epoxy bromopropane is 3.5-5 mole parts; more preferably, based on 1 mole part of the 1, 4-bis (3-aminopropyl) piperazine, the mole part of the epoxy bromopropane is 4-5 mole parts. The desulfurizer provided by the invention has the advantages of rapid desulfurization, good desulfurization effect, high sulfur capacity and partial regeneration.

Description

Technical Field

[0001] The invention belongs to the technical field of petrochemical industry, and particularly relates to a desulfurizing agent for oil fields and a preparation method thereof. Background Art

[0002] During the oil well exploitation process, a large amount of hydrogen sulfide is produced along with crude oil production due to factors such as thermochemical reduction of sulfate, thermochemical decomposition of unstable sulfur-containing compounds, and reduction by sulfate-reducing bacteria. Hydrogen sulfide is a highly toxic, flammable and explosive dangerous gas that seriously endangers personal safety. In addition, hydrogen sulfide is extremely corrosive and can easily cause hydrogen embrittlement and stress cracking of metals, leading to safety accidents and huge economic losses. At present, the methods for controlling hydrogen sulfide in oil field exploitation and gathering and transportation processes include physical methods, chemical methods, and biological methods. Adding liquid desulfurizers to single wells and gathering and transportation stations in oil fields is a simple and effective chemical means to remove hydrogen sulfide.

[0003] CN116162068B discloses a triazine desulfurizer and a preparation method thereof, belonging to the field of petroleum technology. The method reacts 2-aminoethanol and formaldehyde to obtain an intermediate A; reacts the intermediate A with dichlorothionyl to obtain an intermediate B; and reacts the intermediate B with N-methylaniline to obtain a triazine desulfurizer. The triazine desulfurizer prepared by the present invention can stably exist in an acidic environment, has good stability, and prolongs the service life; the triazine desulfurizer of the present invention has a high benzene ring content, and can be mutually dissolved with aromatic hydrocarbons in crude oil through π-π stacking, thereby enhancing the solubility of the triazine desulfurizer, thereby promoting its full contact with sulfur-containing substances and improving the desulfurization effect. The triazine desulfurizer of the present invention has excellent instantaneous desulfurization performance, and is therefore of great significance for inhibiting hydrogen sulfide in the crude oil storage and transportation system of the oil field, and achieving oil field production safety, environmental protection, and energy conservation and emission reduction. However, the synthesis process of the present invention is complicated, the application cost is high, and it is not economical.

[0004] CN115651696B discloses a desulfurizer for liquefied petroleum gas and a preparation method thereof, belonging to the field of petrochemical technology. The desulfurizer uses expanded graphite as a matrix, and undergoes reflux oxidation, doping and composite, epoxy modification and grafting modification treatments in sequence. Through composite doping with manganese, titanium and cerium, an adsorption-activation-doping system is formed to improve the physical adsorption performance of the matrix to sulfides; through the characteristics of KH560 in a weak acid and weak base environment, epoxy groups are introduced to the surface of the composite matrix, and then hydroxyethyl hexahydro-s-triazine is used to open the ring with the epoxy group under the catalysis of strongly alkaline potassium tert-butoxide, and a triazine ring structure is grafted onto the surface, which can directly react with sulfides to achieve the effect of chemical desulfurization. However, the desulfurization rate of the desulfurizer is not high in production, and the dosage is large. Summary of the invention

[0005] The present invention aims at the above-mentioned deficiencies of the prior art and provides a desulfurizer for oil fields and a preparation method thereof. The desulfurizer has the advantages of rapid desulfurization, good desulfurization effect, high sulfur capacity and partial regeneration.

[0006] Therefore, in order to achieve the above-mentioned purpose, on the one hand, the present invention discloses a desulfurizer for oil field, and the molecular structure of the desulfurizer is as follows:

[0007]

[0008] On the other hand, the present invention discloses a method for preparing a desulfurizer for oil fields, the method comprising: subjecting 1,4-bis(3-aminopropyl)piperazine to a substitution reaction with epibromopropane in an alkaline ethanol solution; and subjecting the substitution reaction product to a ring-opening reaction in a weakly acidic environment.

[0009] The desulfurizing agent of the present invention belongs to the azine type desulfurizing agent. The desulfurizing principle is as follows:

[0010] (1) The aqueous solution of the desulfurizer of the present invention is alkaline and has a certain adsorption effect on hydrogen sulfide;

[0011] (2) The four nitrogen atoms in the desulfurizer molecule of the present invention are tertiary amines, all of which are weakly alkaline and can adsorb hydrogen sulfide;

[0012] (3) The desulfurizer molecule of the present invention has 8 hydroxyl groups, which is a polar molecule. According to the principle of like dissolves like, it has a certain dissolving effect on the polar molecule hydrogen sulfide;

[0013] (4) The nitrogen atom on the oxazine ring of the desulfurizing agent of the present invention can undergo a substitution reaction with sulfur to completely remove hydrogen sulfide;

[0014] (5) The polyol amines generated after the nitrogen atom substitution reaction on the oxazine ring of the desulfurizing agent of the present invention are also typical desulfurizing agents.

[0015] The desulfurization effect of the present invention is the comprehensive result of multiple factors.

[0016] Compared with the prior art, the present invention has the following beneficial effects and advantages:

[0017] (1) The desulfurizer of the present invention has the characteristics of wide raw material sources, simple synthesis process, clean and pollution-free process;

[0018] (2) The desulfurizer of the present invention has the characteristics of good desulfurization effect, rapid desulfurization and high sulfur capacity;

[0019] (3) After desulfurization, the desulfurizer of the present invention has a certain regeneration ability after reacting with carbon dioxide at high temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a device for measuring the sulfur content of liquid desulfurizer;

[0021] Figure 2 The desulfurizing agent T of the present invention 8 Infrared IR images;

[0022] In the figure: 1-gas cylinder; 2-thermometer; 3-first anti-backflow valve; 4-CaCl 2 Drying tube; 5-desulfurizing agent solution; 6-magnetic stirrer; 7-diffusion head; 8-first glass tube; 9-second anti-backflow valve; 10-second glass tube; 11-sodium hydroxide solution. DETAILED DESCRIPTION

[0023] 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.

[0024] According to the first aspect of the present invention, the present invention discloses a desulfurizer for oil fields, wherein the molecular structure of the desulfurizer is as follows:

[0025]

[0026] According to a second aspect of the present invention, the present invention provides a method for preparing a desulfurizer for oil fields, the preparation method comprising: subjecting 1,4-bis(3-aminopropyl)piperazine to a substitution reaction with epibromopropane in an alkaline ethanol solution; and subjecting the substitution reaction product to a ring-opening reaction in a weakly acidic environment.

[0027] In the present invention, preferably, based on 1 mole of 1,4-bis(3-aminopropyl)piperazine, the amount of epibromohydrin is 3.5-5 moles; more preferably, based on 1 mole of 1,4-bis(3-aminopropyl)piperazine, the amount of epibromohydrin is 4-5 moles.

[0028] In the present invention, preferably, the mass ratio of ethanol to 1,4-bis(3-aminopropyl)piperazine is 3-5:1.

[0029] In the present invention, preferably, the alkaline environment is pH 10-11.

[0030] In the present invention, preferably, the substitution reaction temperature is 60-70° C., and the reaction time is 1-4 h.

[0031] More preferably, the substitution reaction temperature is 60-65° C., and the reaction time is 1-2 h.

[0032] In the present invention, preferably, the weakly acidic environment is pH 3-4.

[0033] In the present invention, preferably, the ring-opening reaction temperature is 50-60° C., and the reaction time is 30-60 min.

[0034] More preferably, the ring-opening reaction temperature is 50-55°C, and the reaction time is 30-45 min.

[0035] According to a more specific preferred embodiment, the specific steps of the method for preparing the desulfurizer for oil field are as follows:

[0036] (1) Add 1,4-bis(3-aminopropyl)piperazine and ethanol to the reactor, add 2 mol / L sodium hydroxide solution to the first high-position dropping funnel, drip it into the reactor, adjust the pH to 10-11, add epibromopropane to the second high-position dropping funnel, drip epibromopropane into the reactor with the second high-position dropping funnel, control the pH of the reactor to 10-11 with the first high-position dropping funnel, raise the temperature to 60-70°C after the dropping is completed, keep the temperature for reaction, and cool to below 40°C;

[0037] (2) adding distilled water to the reaction mixture, adjusting the pH to 3-4 with 2 mol / L hydrochloric acid, heating to 50-60° C. while stirring, and reacting at this temperature to obtain an ethanol solution of the product;

[0038] (3) The pH of the ethanol solution of the product is adjusted to 8-9 with 10 wt% ammonia water, and the fraction below 80° C. is distilled off under reduced pressure. The residue is transferred to a rotary evaporator and distilled under reduced pressure. The fraction at 110-150° C. is collected to obtain a light yellow liquid product, i.e., the product desulfurizer.

[0039] Preferably, in step (2), the mass ratio of distilled water to 1,4-bis(3-aminopropyl)piperazine is 0.3-2:1.

[0040] The reaction equation for the synthesis of the desulfurizing agent is as follows:

[0041]

[0042] 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. In addition, the various different embodiments of the present invention can also be combined arbitrarily, 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.

[0043] The present invention will be further described below with reference to specific embodiments.

[0044] In the present invention, the devices or equipment used are all conventional devices or equipment known in the art and are commercially available.

[0045] In the following examples and comparative examples, unless otherwise specified, all reagents used were commercially available chemically pure reagents.

[0046] Example 1

[0047] (1) Add 0.2 mol 1,4-bis(3-aminopropyl)piperazine and 120 g ethanol to the reactor, add 2 mol / L sodium hydroxide solution to the first high-position dropping funnel, add it dropwise to the reactor, adjust the pH to 10-11, add 0.7 mol epibromopropane to the second high-position dropping funnel, add epibromopropane dropwise to the reactor with the second high-position dropping funnel, control the pH of the reactor to 10-11 with the first high-position dropping funnel, raise the temperature to 60°C after the addition is complete, keep the temperature for 1 hour, and cool to below 40°C;

[0048] (2) Add 12 g of distilled water to the reaction mixture, adjust the pH to 3-4 with 2 mol / L hydrochloric acid, raise the temperature to 50° C. while stirring, and keep the temperature for 30 min to obtain an ethanol solution of the product;

[0049] (3) The ethanol solution of the product was adjusted to pH 8-9 with 10 wt% ammonia water, and the fraction below 80°C was removed by vacuum distillation. The residue was transferred to a rotary evaporator and vacuum distilled to collect the fraction at 110-150°C to obtain a light yellow liquid product, i.e., the product desulfurizer T 1 .

[0050] Example 2

[0051] (1) Add 0.2 mol 1,4-bis(3-aminopropyl)piperazine and 138 g ethanol to the reactor, add 2 mol / L sodium hydroxide solution to the first high-position dropping funnel, add it dropwise to the reactor, adjust the pH to 10-11, add 0.75 mol epibromopropane to the second high-position dropping funnel, add epibromopropane dropwise to the reactor with the second high-position dropping funnel, control the pH of the reactor to 10-11 with the first high-position dropping funnel, raise the temperature to 70°C after the addition is complete, keep the temperature for reaction for 1.5 hours, and cool to below 40°C;

[0052] (2) Add 20 g of distilled water to the reaction mixture, adjust the pH to 3-4 with 2 mol / L hydrochloric acid, raise the temperature to 52° C. while stirring, and keep the temperature for 30 min to obtain an ethanol solution of the product;

[0053] (3) The ethanol solution of the product was adjusted to pH 8-9 with 10 wt% ammonia water, and the fraction below 80°C was removed by vacuum distillation. The residue was transferred to a rotary evaporator and vacuum distilled to collect the fraction at 110-150°C to obtain a light yellow liquid product, i.e., the product desulfurizer T 2 .

[0054] Example 3

[0055] (1) Add 0.2 mol 1,4-bis(3-aminopropyl)piperazine and 152 g ethanol to the reactor, add 2 mol / L sodium hydroxide solution to the first high-position dropping funnel, add it dropwise to the reactor, adjust the pH to 10-11, add 0.8 mol epibromopropane to the second high-position dropping funnel, add epibromopropane dropwise to the reactor with the second high-position dropping funnel, control the pH of the reactor to 10-11 with the first high-position dropping funnel, raise the temperature to 60°C after the addition is complete, keep the temperature for 2 hours, and cool to below 40°C;

[0056] (2) Add 35 g of distilled water to the reaction mixture, adjust the pH to 3-4 with 2 mol / L hydrochloric acid, raise the temperature to 53° C. while stirring, and keep the temperature for 30 min to obtain an ethanol solution of the product;

[0057] (3) The ethanol solution of the product was adjusted to pH 8-9 with 10 wt% ammonia water, and the fraction below 80°C was removed by vacuum distillation. The residue was transferred to a rotary evaporator and vacuum distilled to collect the fraction at 110-150°C to obtain a light yellow liquid product, i.e., the product desulfurizer T 3 .

[0058] Example 4

[0059] (1) Add 0.2 mol 1,4-bis(3-aminopropyl)piperazine and 152 g ethanol to the reactor, add 2 mol / L sodium hydroxide solution to the first high-position dropping funnel, add it dropwise to the reactor, adjust the pH to 10-11, add 0.83 mol epibromopropane to the second high-position dropping funnel, add epibromopropane dropwise to the reactor with the second high-position dropping funnel, control the pH of the reactor to 10-11 with the first high-position dropping funnel, raise the temperature to 65°C after the addition is complete, keep the temperature for reaction for 2.5 hours, and cool to below 40°C;

[0060] (2) Add 50 g of distilled water to the reaction mixture, adjust the pH to 3-4 with 2 mol / L hydrochloric acid, raise the temperature to 55° C. while stirring, and keep the temperature for 50 min to obtain an ethanol solution of the product;

[0061] (3) The ethanol solution of the product was adjusted to pH 8-9 with 10 wt% ammonia water, and the fraction below 80°C was removed by vacuum distillation. The residue was transferred to a rotary evaporator and vacuum distilled to collect the fraction at 110-150°C to obtain a light yellow liquid product, i.e., the product desulfurizer T 4 .

[0062] Example 5

[0063] (1) Add 0.2 mol 1,4-bis(3-aminopropyl)piperazine and 178 g ethanol to the reactor, add 2 mol / L sodium hydroxide solution to the first high-position dropping funnel, add it dropwise to the reactor, adjust the pH to 10-11, add 0.87 mol epibromopropane to the second high-position dropping funnel, add epibromopropane dropwise to the reactor with the second high-position dropping funnel, and control the pH of the reactor to 10-11 with the first high-position dropping funnel. After the addition is completed, heat to 62°C, keep the temperature for 3 hours, and cool to below 40°C;

[0064] (2) Add 50 g of distilled water to the reaction mixture, adjust the pH to 3-4 with 2 mol / L hydrochloric acid, raise the temperature to 56° C. while stirring, and keep the temperature for 45 min to obtain an ethanol solution of the product;

[0065] (3) The ethanol solution of the product was adjusted to pH 8-9 with 10 wt% ammonia water, and the fraction below 80°C was removed by vacuum distillation. The residue was transferred to a rotary evaporator and vacuum distilled to collect the fraction at 110-150°C to obtain a light yellow liquid product, i.e., the product desulfurizer T 5 .

[0066] Example 6

[0067] (1) Add 0.2 mol 1,4-bis(3-aminopropyl)piperazine and 183 g ethanol to the reactor, add 2 mol / L sodium hydroxide solution to the first high-position dropping funnel, add it dropwise to the reactor, adjust the pH to 10-11, add 0.92 mol epibromopropane to the second high-position dropping funnel, add epibromopropane dropwise to the reactor with the second high-position dropping funnel, and control the pH of the reactor to 10-11 with the first high-position dropping funnel. After the addition is completed, heat to 67°C, keep the temperature for 4 hours, and cool to below 40°C;

[0068] (2) Add 70 g of distilled water to the reaction mixture, adjust the pH to 3-4 with 2 mol / L hydrochloric acid, raise the temperature to 57° C. while stirring, and keep the temperature for 60 min to obtain an ethanol solution of the product;

[0069] (3) The ethanol solution of the product was adjusted to pH 8-9 with 10 wt% ammonia water, and the fraction below 80°C was removed by vacuum distillation. The residue was transferred to a rotary evaporator and vacuum distilled to collect the fraction at 110-150°C to obtain a light yellow liquid product, i.e., the product desulfurizer T 6 .

[0070] Example 7

[0071] (1) Add 0.2 mol 1,4-bis(3-aminopropyl)piperazine and 196 g ethanol to the reactor, add 2 mol / L sodium hydroxide solution to the first high-position dropping funnel, add it dropwise to the reactor, adjust the pH to 10-11, add 0.96 mol epibromopropane to the second high-position dropping funnel, add epibromopropane dropwise to the reactor with the second high-position dropping funnel, control the pH of the reactor to 10-11 with the first high-position dropping funnel, raise the temperature to 68°C after the addition is complete, keep the temperature for 4 hours, and cool to below 40°C;

[0072] (2) Add 70 g of distilled water to the reaction mixture, adjust the pH to 3-4 with 2 mol / L hydrochloric acid, raise the temperature to 58° C. while stirring, and keep the temperature for 50 min to obtain an ethanol solution of the product;

[0073] (3) The ethanol solution of the product was adjusted to pH 8-9 with 10 wt% ammonia water, and the fraction below 80°C was removed by vacuum distillation. The residue was transferred to a rotary evaporator and vacuum distilled to collect the fraction at 110-150°C to obtain a light yellow liquid product, i.e., the product desulfurizer T 7 .

[0074] Example 8

[0075] (1) Add 0.2 mol 1,4-bis(3-aminopropyl)piperazine and 200 g ethanol to the reactor, add 2 mol / L sodium hydroxide solution to the first high-position dropping funnel, add it dropwise to the reactor, adjust the pH to 10-11, add 1 mol epibromopropane to the second high-position dropping funnel, add epibromopropane to the reactor dropwise with the second high-position dropping funnel, and control the pH of the reactor to 10-11 with the first high-position dropping funnel. After the addition is completed, heat to 63°C, keep the temperature for 4 hours, and cool to below 40°C;

[0076] (2) Add 80 g of distilled water to the reaction mixture, adjust the pH to 3-4 with 2 mol / L hydrochloric acid, raise the temperature to 60° C. while stirring, and keep the temperature for 60 min to obtain an ethanol solution of the product;

[0077] (3) The ethanol solution of the product was adjusted to pH 8-9 with 10 wt% ammonia water, and the fraction below 80°C was removed by vacuum distillation. The residue was transferred to a rotary evaporator and vacuum distilled to collect the fraction at 110-150°C to obtain a light yellow liquid product, i.e., the product desulfurizer T 8 .

[0078] Example 9 Evaluation of desulfurizing agent

[0079] The effect of the desulfurizer of the present invention is evaluated, and the evaluation method refers to Q / SH10202872-2021 "General Technical Conditions for Desulfurizers".

[0080] (1) The experiment should be carried out with lead acetate test paper (see Figure 1 ) is carried out without discoloration. If the lead acetate test paper in the second glass tube 10 changes color, stop the experiment immediately, turn off the gas source, open the doors and windows, and quickly evacuate to the upwind vent, build a fence and isolate, and deal with it according to the emergency plan.

[0081] (2) Prepare a 10% by mass desulfurization agent aqueous solution.

[0082] (3) Weigh about 200 g (accurate to 0.01 g) of 10% aqueous solution of desulfurizer, record the mass as m, and add it into the reaction bottle.

[0083] (4) Weigh the total mass m of the reaction bottle and the calcium chloride drying tube 1 .

[0084] (5) Add 300 mL of 10% sodium hydroxide solution to a 500 mL absorption bottle. Figure 1 It is required to connect the device in a fume hood and check the air tightness.

[0085] (6) When the liquid in the reaction bottle is heated to 60°C, turn on the rotor in the reaction bottle, adjust the flow rate of the hydrogen sulfide bottle, and start the experiment.

[0086] (7) When the lead acetate test paper in the first glass tube 8 turns black, weigh the reaction bottle and the drying tube. Weigh them every half an hour until constant weight is reached. Record the mass m. 2 .

[0087] (8) Open the nitrogen bottle and remove the residual H in the pipeline and reaction tube. 2 S gas flushing clean.

[0088] (9) Replace the desulfurization agent solution in the reaction bottle with distilled water, repeat steps (2)-(6) to conduct a blank experiment. Before absorbing hydrogen sulfide, weigh the mass of the reaction bottle and the drying tube to m 3 After the experiment, the mass of the reaction bottle and the drying tube is weighed as m 4 .

[0089] (10) Calculation: The measured saturated sulfur capacity is calculated according to the following formula.

[0090]

[0091] Where:

[0092] S——sulfur capacity;

[0093] m 2 ——The mass of the absorption bottle and drying tube when the desulfurizer solution absorbs hydrogen sulfide, g;

[0094] m 1 ——The mass of the absorption bottle and drying tube when the desulfurizer solution does not absorb hydrogen sulfide, g;

[0095] m 3 ——Mass of the absorption bottle and drying tube when no hydrogen sulfide is absorbed in the blank experiment, g;

[0096] m 4 ——Mass of absorption bottle and drying tube during blank experiment of absorbing hydrogen sulfide, g.

[0097] Use T 1 -T 8 , diethanolamine, and triazine desulfurizer to determine the sulfur capacity. The desulfurization results are shown in Table 1, T 8 The sulfur capacity is the highest and the desulfurization effect is the best.

[0098] Table 1 Desulfurization test results of desulfurizer

[0099] Desulfurization agent <![CDATA[Weight gain (m 2 -m 1 ), g]]> Sulfur content S, % <![CDATA[T 1 ]]> 8.6 20.5 <![CDATA[T 2 ]]> 8.8 21.5 <![CDATA[T 3 ]]> 9.1 23.0 <![CDATA[T 4 ]]> 9.3 24.0 <![CDATA[T 5 ]]> 9.5 25.0 <![CDATA[T 6 ]]> 9.4 24.5 <![CDATA[T 7 ]]> 9.7 26.0 <![CDATA[T 8 ]]> 9.8 26.5 Distilled water 4.5 0.0 Diethanolamine 7.3 14.0 Triazine desulfurization agent 6.8 11.5

[0100] It can be seen from Table 1 that the oil field desulfurizer T of the present invention 1 -T 8 When the concentration is 10wt%, the sulfur capacity is greater than 20%, and the highest reaches 26.5% (T 8 ), while the sulfur capacities of the comparative examples of diethanolamine and triazine desulfurizers are 14.0% and 11.5% respectively, which are significantly lower than those of the present invention. The desulfurizer for oil fields of the present invention has a good desulfurization effect.

[0101] Example 10 Infrared Spectroscopy

[0102] Infrared spectroscopy was used to characterize T 8 The results were characterized as Figure 2 shown.

[0103] from Figure 2 It can be seen that 3424cm -1 It is the OH bond stretching vibration peak; 2924cm -1 It is the stretching vibration peak of the CH bond; 1352cm -1 It is the OH bond bending vibration peak; 1125cm-1 is the CO bond stretching vibration peak; 1035cm -1 It is the CN bond stretching vibration peak.

[0104] 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 preparation method of a desulfurizer for oil fields, characterized in that, the preparation method includes: 1,4-bis(3-aminopropyl)piperazine undergoes a substitution reaction with epibromohydrin in an alkaline ethanol solution; the substitution reaction product undergoes a ring-opening reaction in a weakly acidic environment.

2. The preparation method of a desulfurizer for oil fields according to claim 1, characterized in that, based on 1 mole part of 1,4-bis(3-aminopropyl)piperazine, the amount of substance of the epibromohydrin is 3.5 - 5 mole parts.

3. The preparation method of a desulfurizer for oil fields according to claim 2, characterized in that, based on 1 mole part of 1,4-bis(3-aminopropyl)piperazine, the amount of substance of the epibromohydrin is 4 - 5 mole parts.

4. The preparation method of a desulfurizer for oil fields according to claim 1, characterized in that, the mass ratio of the ethanol to 1,4-bis(3-aminopropyl)piperazine is 3 - 5:

1.

5. The preparation method of a desulfurizer for oil fields according to claim 1, characterized in that, the alkaline environment is pH 10 - 11.

6. The preparation method of a desulfurizer for oil fields according to claim 1, characterized in that, the substitution reaction temperature is 60 - 70 °C, and the reaction time is 1 - 4 h.

7. The preparation method of a desulfurizer for oil fields according to claim 6, characterized in that, the substitution reaction temperature is 60 - 65 °C, and the reaction time is 1 - 2 h.

8. The preparation method of a desulfurizer for oil fields according to claim 1, characterized in that, the weakly acidic environment is pH 3 - 4.

9. The preparation method of a desulfurizer for oil fields according to claim 1, characterized in that, the ring-opening reaction temperature is 50 - 60 °C, and the reaction time is 30 - 60 min.

10. The preparation method of a desulfurizer for oil fields according to claim 9, characterized in that, the ring-opening reaction temperature is 50 - 55 °C, and the reaction time is 30 - 45 min.

11. The preparation method of a desulfurizer for oil fields according to claim 1, characterized in that, the specific steps of the preparation method are as follows: (1) Add 1,4-bis(3-aminopropyl)piperazine and ethanol into a reactor, add a 2 mol / L sodium hydroxide solution into the first high-position dropping funnel, drip it into the reactor, adjust the pH to 10 - 11, add epibromohydrin into the second high-position dropping funnel, the second high-position dropping funnel drips epibromohydrin into the reactor, use the first high-position dropping funnel to control the pH of the reactor at 10 - 11, after dripping, raise the temperature to 60 - 70 °C, keep the temperature for reaction, and cool to below 40 °C; (2) Add distilled water to the above reaction mixture, adjust the pH to 3 - 4 with 2 mol / L hydrochloric acid, heat up to 50 - 60 °C while stirring, keep the temperature for reaction, and obtain an ethanol solution of the product; (3) Adjust the pH of the ethanol solution of the product to 8 - 9 with 10 wt% ammonia water, distill off the fractions below 80 °C under reduced pressure, transfer the remaining distillate to a rotary evaporator, distill under reduced pressure, and collect the fractions at 110 - 150 °C to obtain a light yellow liquid product, namely the product desulfurizer.

12. The preparation method of a desulfurizer for oil fields according to claim 11, characterized in that, the mass ratio of the distilled water to 1,4-bis(3-aminopropyl)piperazine is 0.3-2:

1.

13. A desulfurizer for oil fields, characterized in that, the molecular structural formula of the desulfurizer is as follows:

Images