Defoaming agent and preparation method thereof, desulfurization solvent and preparation method and application thereof

Abstract

The invention relates to the field of gas purification, and discloses a defoaming agent and a preparation method thereof, and a desulfurization solvent and a preparation method and application thereof. The defoaming agent is a mixture composed of dimethyl silicone oil, distearoyl ethylene diamine and polypropylene glycol; wherein the mass ratio of the dimethyl silicone oil to the distearoyl ethylene diamine to the polypropylene glycol is (1-6): (1-2): (1-2). The defoaming agent provided by the invention is high in defoaming efficiency and good in foam inhibition effect, the stability of an amine solution in the desulfurization solvent and the high-selectivity H2S absorption capacity of the desulfurization solvent are improved, and a guarantee is provided for normal and stable operation of a selective desulfurization system.

Description

Technical Field

[0001] The invention relates to the field of gas purification, and in particular to a defoaming agent and a preparation method thereof, a desulfurization solvent and a preparation method and application thereof. Background Art

[0002] The raw gas of natural gas, refinery gas and biomass fuel gas often contains a certain amount of H2S and CO2. H2S is a highly toxic and colorless combustible gas. Its presence seriously threatens personal safety and causes corrosion of equipment and pipelines. At the same time, hydrogen sulfide is highly irritating and toxic even at extremely low concentration levels. Therefore, it must be effectively treated before transportation and processing to meet emission requirements.

[0003] After years of research and application, the selective desulfurization process has become an important direction for deacidification process research. Compared with traditional selective desulfurization solvents, the research and development of compound amine liquid formulas based on MDEA mainly focuses on high desulfurization selectivity, low regeneration energy consumption and process optimization. The investigation of foaming characteristics and their mechanisms is relatively small and lacks a certain degree of systematicity. However, the solid particles, organic matter and metal ions present in the selective desulfurization system based on MDEA significantly affect the foaming of the amine liquid formula, and affect the efficiency and stability of the selective desulfurization system. Therefore, it is very necessary to study its foaming characteristics.

[0004] With the increasing attention paid to the foaming phenomenon in production, the method of adding special defoamers has become the main application method in various industries. Domestic and foreign defoamers can be divided into polyether type, silicone type, amide type and polyether mixed type in terms of composition. Compared with traditional methods, they have the advantages of fast defoaming, long foam suppression time and easy use. However, the defoaming effect of traditional defoamers is easily affected by the environment, which makes the stability worse, the adaptability is not high, and it may be toxic and cause pollution to the environment. In addition, there is currently little research on special defoamers for natural gas, refinery gas and biomass fuel gas, especially defoamers with selective desulfurization amine liquid formula.

[0005] Therefore, it is very necessary to develop the foaming characteristics of the selective desulfurization amine liquid formula and obtain a defoamer with good stability, good adaptability, and good defoaming and anti-foaming properties. Summary of the invention

[0006] The purpose of the present invention is to overcome the problem that there is little research on the defoamer for selective desulfurization amine liquid in the prior art, and to provide a defoamer and a preparation method thereof, a desulfurization solvent and a preparation method and application thereof.

[0007] In order to achieve the above object, the first aspect of the present invention provides a defoaming agent, wherein the defoaming agent comprises dimethyl silicone oil, distearyl ethylenediamine and polypropylene glycol;

[0008] Wherein, the mass ratio of the dimethyl silicone oil, distearyl ethylenediamine and polypropylene glycol is (1-6): (1-2): (1-2).

[0009] A second aspect of the present invention provides a method for preparing a defoaming agent, wherein dimethyl silicone oil, distearyl ethylenediamine and polypropylene glycol are stirred and mixed to obtain the defoaming agent.

[0010] The third aspect of the present invention provides a desulfurization solvent, wherein the desulfurization solvent comprises an amine solution and a defoamer, the amine solution comprises N-methyldiethanolamine, an activator and a solvent, and the mass ratio of the amine solution to the defoamer is 1:0.01-0.1;

[0011] Wherein, based on the total amount of the amine solution, the content of N-methyldiethanolamine and the activator in the amine solution is 25-58wt%;

[0012] Wherein, the defoaming agent is the defoaming agent described in the first aspect or the defoaming agent prepared by the method described in the second aspect.

[0013] The fourth aspect of the present invention provides a method for preparing a desulfurization solvent, wherein the method comprises: stirring the N-methyldiethanolamine, an activator and a solvent to obtain an amine solution; and then mixing the amine solution with a defoaming agent until uniform to obtain the desulfurization solvent.

[0014] A fifth aspect of the present invention provides an application of the desulfurization solvent described in the third aspect or the desulfurization solvent prepared by the method described in the fourth aspect for selectively removing H2S from natural gas, refinery gas or biomass fuel gas.

[0015] Through the above technical solution, the present invention has the following beneficial effects:

[0016] (1) The defoaming agent provided by the present invention can inhibit the foaming of the amine solution and can quickly eliminate the foam generated by the desulfurization solvent when absorbing sulfur-containing gas. It has a small filling amount, high defoaming efficiency, good foam suppression effect, low cost, and is green and environmentally friendly. The preparation method is simple, the process requirements are not high, and it is easy to mass produce, and it has good promotion and application value.

[0017] (2) The defoaming agent provided by the present invention, when combined with an amine solution to obtain a desulfurization solvent, has a higher ability to selectively absorb H2S than MDEA or a common composite desulfurization solvent based on MDEA when treating a mixed gas with a high carbon-sulfur ratio. The defoaming agent improves the stability of the amine solution in the desulfurization solvent, thereby providing a guarantee for the normal and stable operation of the selective desulfurization system. DETAILED DESCRIPTION

[0018] 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.

[0019] The first aspect of the present invention provides a defoaming agent, wherein the defoaming agent comprises dimethyl silicone oil, distearyl ethylenediamine and polypropylene glycol;

[0020] Wherein, the mass ratio of the dimethyl silicone oil, distearyl ethylenediamine and polypropylene glycol is (1-6): (1-2): (1-2).

[0021] The inventors of the present invention have found through research that the defoamer provided by the present invention can inhibit the foaming of the amine solution in the desulfurization solvent, and can quickly eliminate the foam generated by the desulfurization solvent when absorbing sulfur-containing gas, with a small filling amount, high defoaming efficiency and good foam suppression effect. In the present invention, the defoamer can improve the stability of the amine solution in the desulfurization solvent.

[0022] In the present invention, the mass ratio of the dimethyl silicone oil, distearyl ethylenediamine and polypropylene glycol is (1-6): (1-2): (1-2). Controlling the mass ratio of the dimethyl silicone oil, distearyl ethylenediamine and polypropylene glycol within the above range is conducive to making the defoaming agent have the best comprehensive performance, high defoaming efficiency, and good anti-foaming effect, so that the defoaming agent can quickly and effectively reduce the generation and accumulation of foam during the desulfurization process, thereby maintaining the high efficiency and stability of the desulfurization process, and a relatively small amount can achieve the desired defoaming effect, reduce costs and the use of chemicals, and meet green environmental protection requirements.

[0023] In some embodiments of the present invention, preferably, the defoaming time of the defoaming agent is ≤4.1s, preferably 2.5-4s.

[0024] A second aspect of the present invention provides a method for preparing a defoaming agent, wherein dimethyl silicone oil, distearyl ethylenediamine and polypropylene glycol are stirred and mixed to obtain the defoaming agent.

[0025] In the present invention, the mixing method is not particularly limited, and is preferably carried out under stirring conditions, for example, stirring can be performed at a rotation speed of 550-750 rpm for 5-11 hours. The preparation method of the defoamer is simple, has low process requirements, is easy to mass produce, and has good promotion and application value.

[0026] The third aspect of the present invention provides a desulfurization solvent, wherein the desulfurization solvent comprises an amine solution and a defoamer, the amine solution comprises N-methyldiethanolamine, an activator and a solvent, and the mass ratio of the amine solution to the defoamer is 1:0.01-0.1;

[0027] Wherein, based on the total amount of the amine solution, the total content of N-methyldiethanolamine and the activator in the amine solution is 25-58wt%, preferably 40-55wt%;

[0028] Wherein, the defoaming agent is the defoaming agent described in the first aspect or the defoaming agent prepared by the method described in the second aspect.

[0029] In the present invention, an amine solution and a defoaming agent are combined to obtain the desulfurization solvent. The defoaming agent can inhibit the foaming of the amine solution and can quickly eliminate the foam generated by the desulfurization solvent when absorbing sulfur-containing gas. The filling amount is small, the defoaming efficiency is high, and the foam suppression effect is good. In addition, in the present invention, when treating a mixed gas with a high carbon-sulfur ratio, the desulfurization solvent has a higher ability to selectively absorb H2S than MDEA or an ordinary composite desulfurization solvent with MDEA as the main body. The defoaming agent improves the stability of the amine solution in the desulfurization solvent, providing a guarantee for the normal and stable operation of the selective desulfurization system.

[0030] In the present invention, the mass ratio of the amine solution to the defoamer is 1:0.01-0.1. Controlling the mass ratio of the amine solution to the defoamer within the above range can enable the defoamer to fully inhibit the foaming of the amine solution and quickly eliminate the foam generated by the desulfurization solvent when absorbing sulfur-containing gas. In the present invention, the mass ratio of the amine solution to the defoamer is less than 1:0.1, and the defoamer is excessive, resulting in excessive dispersion of the defoamer, reducing its adsorption and destructive ability at the gas-liquid interface, and the excessive defoamer reacts with other components of the amine solution to form unstable substances, affecting the defoaming effect; the mass ratio of the amine solution to the defoamer is greater than 1:0.01, and the defoamer is too little, and the defoaming effect of the defoamer cannot reach the best.

[0031] In some embodiments of the present invention, preferably, the mass ratio of the N-methyldiethanolamine to the activator is 25-45:3-10. In the present invention, controlling the mass ratio of the N-methyldiethanolamine to the activator within the above range is conducive to better dispersion of the defoamer in the amine solution, and the obtained desulfurization solvent has a higher ability to selectively absorb hydrogen sulfide, which is conducive to improving the desulfurization efficiency and the stability of the amine solution in the desulfurization solvent, and providing a guarantee for the normal and stable operation of the selective desulfurization system.

[0032] In some embodiments of the present invention, preferably, the activator is selected from at least one of diethanolamine, triethanolamine, methyl monoethanolamine, piperazine, cyclopentane and 2-amino-2-methyl-1-propanol, preferably selected from at least one of diethanolamine, methyl monoethanolamine and 2-amino-2-methyl-1-propanol. In the present invention, the activator has a high ability to selectively absorb H2S, and also has good stability in the desulfurization system, which is conducive to improving the comprehensive performance of the desulfurization solvent.

[0033] In some embodiments of the present invention, preferably, the solvent is selected from water and / or ethanol.

[0034] In some embodiments of the present invention, preferably, the desulfurization selectivity of the desulfurization solvent is ≥58, preferably 188-201.

[0035] The fourth aspect of the present invention provides a method for preparing a desulfurization solvent, wherein the method comprises: first mixing the N-methyldiethanolamine, an activator and a solvent to obtain an amine solution; and then second mixing the amine solution with a defoaming agent to obtain the desulfurization solvent.

[0036] In some embodiments of the present invention, preferably, the first mixing conditions include: a stirring speed of 500-1000 rpm; a stirring time of 4-8 hours. In the present invention, N-methyldiethanolamine, an activator and a solvent are first mixed, wherein the mixing method is not specifically limited, and the first mixing can be carried out under stirring conditions, for example, stirring at a speed of 500-1000 rpm for 4-8 hours.

[0037] In some embodiments of the present invention, preferably, the second mixing condition includes: a stirring speed of 300-500 rpm, and a stirring time of 4-8 hours. In the present invention, the amine solution and the defoamer are second mixed, and the desulfurization solvent is obtained after mixing evenly, wherein the mixing method is not specifically limited, and can be carried out under stirring conditions, for example, the second mixing is carried out at a speed of 300-500 rpm and stirred for 4-8 hours.

[0038] In some embodiments of the present invention, preferably, the use temperature of the defoamer is 25-140°C, preferably 30-130°C. In the present invention, controlling the use temperature of the defoamer within the above range is conducive to making the defoamer have good defoaming effect and safety. The use temperature is greater than 140°C. If the temperature is too high, the molecular structure of the defoamer will change, thereby losing the defoaming ability, and too high a temperature will bring potential safety hazards; if the use temperature is less than 25°C, the temperature is too low, the defoamer cannot effectively reduce the surface tension in the liquid, resulting in a decrease in the defoaming effect, and it will become viscous or solidified, causing the pipeline or equipment to be blocked, affecting the production process.

[0039] In some embodiments of the present invention, preferably, the use pressure of the defoamer is 0.5-8.5MPa, preferably 0.6-8.3MPa. In the present invention, controlling the use pressure of the defoamer within the above range is conducive to making the defoamer have a better defoaming effect and avoiding safety risks and equipment damage. When the use pressure is greater than 8.5MPa, the defoamer molecules will be affected by the additional pressure, resulting in changes in their structure, thereby weakening or losing the defoaming performance, and the high-pressure system has the risk of leakage or rupture; when the use pressure is less than 0.5MPa, the defoamer cannot effectively reduce the surface tension in the liquid, resulting in limited defoaming effect.

[0040] A fifth aspect of the present invention provides an application of the desulfurization solvent described in the third aspect or the desulfurization solvent prepared by the method described in the fourth aspect for selectively removing H2S from natural gas, refinery gas or biomass fuel gas.

[0041] In some embodiments of the present invention, preferably, the content of CO2 in the natural gas, refinery gas or biomass fuel gas is 0.1-25v%, and the content of H2S is 0.1-5v%. In the present invention, the gas concentrations of CO2 and H2S in the gas mixture are within the above ranges, and the defoaming agent can effectively eliminate the bubbles in the desulfurizer to achieve a good defoaming effect. When the gas concentrations of CO2 and H2S in the gas mixture exceed the above ranges, the CO2 and H2S in the gas mixture increase significantly, and the amount of the defoaming agent cannot meet the amount of foam, resulting in a reduced defoaming effect.

[0042] The present invention will be described in detail below through examples.

[0043] Example 1

[0044] (1) Dimethyl silicone oil, distearyl ethylenediamine and polypropylene glycol were weighed in a mass ratio of 3:1:1, and stirred at a rotation speed of 550 rpm for 9 hours to obtain a defoaming agent.

[0045] (2) N-methyldiethanolamine, diethanolamine and methyl monoethanolamine were weighed in a mass ratio of 40:3:2, mixed with deionized water, and stirred at a rotation speed of 600 rpm for 6 hours to obtain an amine solution (45 wt%).

[0046] (3) The defoaming agent and the amine solution are mixed at a mass ratio of 0.05:1, and stirred at a rotation speed of 400 rpm for 6 hours to prepare a uniform solution, namely the desulfurization solvent.

[0047] Example 2

[0048] (1) Dimethyl silicone oil, distearyl ethylenediamine and polypropylene glycol were weighed in a mass ratio of 2:1:1, and stirred at a speed of 550 rpm for 9 hours to obtain a defoaming agent.

[0049] (2) N-methyldiethanolamine and 2-amino-2-methyl-1-propanol were weighed in a mass ratio of 43:5, mixed with deionized water, and stirred at a rotation speed of 600 rpm for 6 hours to obtain an amine solution (48 wt%).

[0050] (3) The defoaming agent and the amine solution are mixed at a mass ratio of 0.05:1, and stirred at a rotation speed of 400 rpm for 6 hours to prepare a uniform solution, namely the desulfurization solvent.

[0051] Example 3

[0052] (1) Dimethyl silicone oil, distearyl ethylenediamine and polypropylene glycol were weighed in a mass ratio of 2:1:1, and stirred at a speed of 550 rpm for 9 hours to obtain a defoaming agent.

[0053] (2) N-methyldiethanolamine and diethanolamine were weighed in a mass ratio of 40:5, stirred at 600 rpm for 6 h, and then mixed with deionized water to obtain an amine solution (45 wt %).

[0054] (3) The defoaming agent and the amine solution are mixed at a mass ratio of 0.05:1, and stirred at a rotation speed of 400 rpm for 6 hours to prepare a uniform solution, namely the desulfurization solvent.

[0055] Example 4

[0056] The method of Example 1 is followed, except that

[0057] In step (1), dimethyl silicone oil, distearyl ethylenediamine and polypropylene glycol are mixed in a mass ratio of 2:1:1 to obtain the defoaming agent;

[0058] In step (3), the defoaming agent and the amine solution are mixed at a mass ratio of 0.02:1 to prepare a uniform solution, namely the desulfurization solvent.

[0059] Example 5

[0060] The method of Example 1 is followed, except that

[0061] In step (1), dimethyl silicone oil, distearyl ethylenediamine and polypropylene glycol are mixed in a mass ratio of 1:2:2 to obtain the defoaming agent.

[0062] Example 6

[0063] The method of Example 1 is followed, except that

[0064] In step (1), dimethyl silicone oil, distearyl ethylenediamine and polypropylene glycol are mixed in a mass ratio of 6:1:1 to obtain the defoaming agent.

[0065] Example 7

[0066] According to the method of Example 1, the difference is that

[0067] In step (2), N-methyldiethanolamine and diethanolamine are weighed in a mass ratio of 60:5, and then mixed with deionized water to obtain an amine solution (65wt%).

[0068] Example 8

[0069] According to the method of Example 1, the difference is that

[0070] In step (2), N-methyldiethanolamine and 2-amino-2-methyl-1-propanol are weighed in a mass ratio of 60:5, and then mixed with deionized water to obtain an amine solution (65 wt%).

[0071] Example 9

[0072] According to the method of Example 1, the difference is that

[0073] In step (2), without adding N-methyldiethanolamine, diethanolamine and deionized water are mixed to obtain an amine solution (45 wt %).

[0074] Example 10

[0075] According to the method of Example 1, the difference is that

[0076] In step (2), without adding N-methyldiethanolamine, methyl monoethanolamine and deionized water are mixed to obtain an amine solution (45 wt %).

[0077] Comparative Example 1

[0078] Without adding the defoaming agent described in step (1), N-methyldiethanolamine and deionized water were mixed to obtain an amine solution (45 wt %).

[0079] Comparative Example 2

[0080] Without adding the defoaming agent described in step (1), N-methyldiethanolamine and diethanolamine were weighed in a mass ratio of 40:5, and then mixed with deionized water to obtain an amine solution (45wt%).

[0081] Comparative Example 3

[0082] The method of Example 1 is followed, except that in step (1), distearyl ethylenediamine and polypropylene glycol are not added; in step (3), the defoaming agent and the amine solution are mixed in a mass ratio of 0.03:1 to prepare a uniform solution, namely the desulfurization solvent.

[0083] Comparative Example 4

[0084] The method of Example 1 is followed, except that in step (1), dimethyl silicone oil is not added, and distearyl ethylenediamine and polypropylene glycol are mixed in a mass ratio of 1:1 to obtain the defoaming agent; in step (3), the defoaming agent and the amine solution are mixed in a mass ratio of 0.02:1 to prepare a uniform solution, i.e., the desulfurization solvent.

[0085] Test Example 1

[0086] Selectivity determination: A mixed gas containing 5v% H2S and 25v% CO2 by volume is passed into an absorption tube filled with the desulfurization solvent, with a gas volume of 80mL / min, and is absorbed by bubbling at 1MPa at a temperature of 40°C. Samples and analysis are performed on the vented gas at regular intervals, and then the gas source is turned off, and the rich liquid after absorption is taken for liquid phase analysis. The H2S in the raw gas and liquid phase is analyzed by iodine titration, the H2S in the purified gas is analyzed by FPD chromatography, the gas phase acid gas is analyzed by Ostwald analyzer, and the liquid phase acid gas is analyzed by gas generation method. The experimental results of the selectivity determination are shown in Table 1.

[0087] Evaluation criteria:

[0088]

[0089] In the formula: l represents the rich liquid phase after absorption, g represents the tail gas phase, [H2S] and [CO2] represent the analyzed concentrations.

[0090] Test Example 2

[0091] Foam performance measurement: Take 20mL of the above desulfurization solvent and put it into a foam height test tube, and then put it into a constant temperature water bath, set the temperature to 40±1°C, and keep the temperature constant for 10 minutes. Nitrogen passes through the rotor flowmeter and passes through the bottom inlet of the foam height test tube. Start timing after the flow rate stabilizes at 450mL / min. After ventilation for 5 minutes, stop ventilation, record the foam height (the difference between the final foam height of the liquid surface and the initial solution height) and defoaming time (start counting after stopping the gas, and stop when the foam just bursts and clear liquid is seen). The results of the selectivity, bubble height and defoaming time of the desulfurization solvent are shown in Table 1.

[0092] Table 1

[0093] serial number Selectivity Bubble height (cm) Defoaming time(s) Example 1 201 3.6 2.5 Example 2 195 3.7 2.6 Example 3 194 3.7 2.9 Example 4 188 3.5 2.9 Example 5 189 3.7 3 Example 6 191 3.6 2.9 Example 7 134 4.7 3.6 Example 8 112 4.9 4 Example 9 62 4.7 3.7 Example 10 58 4.5 3.8 Comparative Example 1 85 8 6.6 Comparative Example 2 117 7.6 6.3 Comparative Example 3 187 4.6 4.2 Comparative Example 4 179 5.3 4.6

[0094] It can be seen from the results in Table 1 that the defoaming agent provided by the present invention has the characteristics of high defoaming efficiency and good antifoaming effect, and improves the stability of the amine solution in the desulfurization solvent and the ability of the desulfurization solvent to absorb H2S with high selectivity. It can be seen from Examples 1-6 in Table 1 that the use of the defoamer provided by the present invention and the mass ratio of each component in the desulfurization solvent being within the preferred range described in the present invention is conducive to making the desulfurization solvent have a higher ability to selectively absorb H2S, and the defoamer has high defoaming efficiency, good anti-foaming effect, bubble height ≤3.7cm, and defoaming time less than 3s; It can be seen from Examples 7-10 in Table 1 that the use of the defoamer provided by the present invention and the dosage of each component in the desulfurization solvent is not completely within the preferred range described in the present invention, the ability of the obtained desulfurization agent to selectively absorb H2S is reduced, and the defoaming efficiency and anti-foaming effect of the defoamer are slightly reduced; Compared with Example 1, Comparative Examples 1 and 2 in Table 1 are different in that no defoamer is added to Comparative Examples 1 and 2, and the ability of the obtained desulfurization solvent to selectively absorb H2S is poor, and the defoaming efficiency and anti-foaming effect are significantly reduced; Compared with Example 1, Comparative Examples 3 and 4 in Table 1 are different in that the defoamer provided by the present invention is not used in Comparative Examples 3 and 4, and the defoaming efficiency and anti-foaming effect of the obtained desulfurization solvent are reduced.

[0095] 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 defoaming agent, characterized in that The defoaming agent comprises dimethyl silicone oil, distearyl ethylenediamine and polypropylene glycol; Wherein, the mass ratio of the dimethyl silicone oil, distearyl ethylenediamine and polypropylene glycol is (1-6): (1-2): (1-2).

2. The defoaming agent according to claim 1, wherein The defoaming time of the defoaming agent is ≤4.1s, preferably 2.5-4s.

3. A method for preparing a defoaming agent, characterized in that: Dimethyl silicone oil, distearyl ethylenediamine and polypropylene glycol are mixed to obtain the defoaming agent.

4. A desulfurization solvent, characterized in that: The desulfurization solvent comprises an amine solution and a defoamer, the amine solution comprises N-methyldiethanolamine, an activator and a solvent, and the mass ratio of the amine solution to the defoamer is 1:0.01-0.1; Wherein, based on the total amount of the amine solution, the total content of N-methyldiethanolamine and the activator in the amine solution is 25-58wt%, preferably 40-55wt%; Wherein, the defoaming agent is the defoaming agent described in claim 1 or 2 or the defoaming agent prepared by the method described in claim 3.

5. The desulfurization solvent according to claim 4, wherein The mass ratio of the N-methyldiethanolamine to the activator is 25-45:3-10.

6. The desulfurization solvent according to claim 4 or 5, wherein The activator is selected from at least one of diethanolamine, triethanolamine, methylmonoethanolamine, piperazine, sulfolane and 2-amino-2-methyl-1-propanol, preferably selected from at least one of diethanolamine, methylmonoethanolamine and 2-amino-2-methyl-1-propanol; Preferably, the solvent is selected from water and / or ethanol.

7. The desulfurization solvent according to any one of claims 4 to 6, wherein: The desulfurization selectivity of the desulfurization solvent is ≥58, preferably 188-201.

8. A method for preparing a desulfurization solvent, characterized in that: The method comprises: first mixing the N-methyldiethanolamine, an activator and a solvent to obtain an amine solution; and then second mixing the amine solution and a defoaming agent to obtain the desulfurization solution.

9. The method according to claim 9, wherein: The first mixing conditions include: a stirring speed of 500-1000 rpm and a stirring time of 4-8 h; Preferably, the second mixing conditions include: stirring speed of 300-500 rpm, stirring time of 4-8 h; Preferably, the defoaming agent is used at a temperature of 25-140°C, preferably 30-130°C, and a pressure of 0.5-8.5 MPa, preferably 0.6-8.3 MPa.

10. Use of the desulfurization solvent according to any one of claims 4 to 7 or the desulfurization solvent prepared by the method according to claim 8 or 9 for selectively removing H2S from natural gas, refinery gas or biomass fuel gas; Preferably, the CO2 content in the natural gas, refinery gas or biomass fuel gas is 0.1-25v%, and the H2S content is 0.1-5v%.

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