Desulfurization absorbent, desulfurization absorbing liquid and application, method for desulfurization of sulfur-containing gas

Abstract

This invention relates to the field of gas purification and discloses a desulfurization absorbent, which, by weight, contains 1-20 parts by weight of an organic guanidine base and 10-70 parts by weight of an alkanolamine. The organic guanidine base has the structure shown in Formula I: Among them, R 1 R 2 R 3 R 4 R 5 Each is independently selected from hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted benzyl, or substituted or unsubstituted aromatic alkyl; or, R 5 With R 1 Or R 4 Ring formation, and / or R 2 With R 3 Cyclic formation. This desulfurization absorbent contains a specific amount of organic guanidine and a specific amount of alcoholamine, which can form a synergistic effect to improve the desulfurization efficiency of the desulfurization absorbent. In addition, the organic guanidine has a specific structure, which can effectively remove multiple harmful gases from sulfur-containing gases and selectively remove carbon dioxide, thereby improving the selectivity and stability of the desulfurization absorbent.

Description

Desulfurization absorbent, desulfurization absorbent and its application, methods for desulfurizing sulfur-containing gases Technical Field

[0001] This invention relates to the field of gas purification technology, specifically to a desulfurization absorbent, a desulfurization absorbent liquid and its application, and a method for desulfurizing sulfur-containing gases. It also includes an organic amine absorbent liquid for deep desulfurization of hydrogen sulfide and mercaptans, and its application, which can selectively remove carbon dioxide. Background Technology

[0002] In recent years, the limits on total sulfur content in natural gas have been further reduced, with the limit for Class I natural gas decreasing from 60 mg / m³. 3 Reduced to 20 mg / m 3 The total sulfur limit for Class II natural gas is 200 mg / m³. 3 Reduced to 100 mg / m 3 The tightening of natural gas quality standards presents more stringent challenges to the removal of organic sulfur compounds (such as methanethiol and ethanethiol) in high-acidity production areas and enterprises containing organic sulfur. Therefore, deep desulfurization is necessary to meet higher natural gas quality requirements, while also reducing environmental pollution and protecting equipment safety. However, current traditional amine absorbent formulations and devices have very low efficiency in removing organic thiols. Organic guanidine compounds are a class of polyamine compounds widely found in nature, commonly found in natural products such as nucleic acids and proteins, and even present in trace amounts in humans and animals. Due to their unique properties as organic bases in chemistry and catalysis, organic guanidines have received widespread attention and are often used as catalysts and associating agents. The basicity of organic guanidines enables them to absorb weakly acidic thiols, thus achieving deep desulfurization. However, due to the large number of organic guanidine compounds, screening is required to find suitable desulfurizing agents, and considerations such as selectivity further increase the difficulty of the process. Summary of the Invention

[0003] The purpose of this invention is to overcome the problems of incomplete desulfurization of sulfur-containing gases and difficulty in removing organic thiols in existing technologies. This invention provides a desulfurization absorbent, a desulfurization absorbent liquid, its application, and a method for desulfurizing sulfur-containing gases. The desulfurization absorbent contains a specific amount of an organic guanidine base and a specific amount of an alcohol amine, which can form a synergistic effect and improve the desulfurization efficiency of the desulfurization absorbent liquid. Furthermore, the organic guanidine base has a specific structure, enabling effective removal of various harmful gases from sulfur-containing gases and selective removal of carbon dioxide, thereby improving the selectivity and stability of the desulfurization absorbent liquid.

[0004] To achieve the above objectives, the first aspect of the present invention provides a desulfurization absorbent, wherein, by weight, the desulfurization absorbent contains 1-20 parts by weight of an organic base guanidine and 10-70 parts by weight of an alcohol amine.

[0005] The organic base guanidine has the structure shown in Formula I:

[0006]

[0007] R1, R2, R3, R4, and R5 are each independently selected from hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted benzyl, or substituted or unsubstituted aromatic alkyl.

[0008] Alternatively, R5 may form a ring with R1 or R4, and / or R2 may form a ring with R3.

[0009] A second aspect of the present invention provides a desulfurization absorbent, wherein, based on the total amount of the absorbent, the absorbent comprises: 1-20 wt% of an organic base guanidine, 10-70 wt% of an alkanolamine and 10-90 wt% of water;

[0010] The organic base guanidine has the structure shown in Formula I:

[0011]

[0012] R1, R2, R3, R4, and R5 are each independently selected from hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted benzyl, or substituted or unsubstituted aromatic alkyl, or R5 is cyclic with R1 or R4, and / or R2 is cyclic with R3.

[0013] The third aspect of the present invention provides the application of the desulfurization absorbent described in the first aspect or the desulfurization absorbent described in the second aspect of the present invention in the desulfurization of sulfur-containing gases.

[0014] A fourth aspect of the present invention provides a method for desulfurizing sulfur-containing gas, wherein the method includes: contacting and adsorbing the sulfur-containing gas and a desulfurization absorbent;

[0015] The gas-liquid ratio of the sulfur-containing gas to the desulfurization absorption liquid is 10-400:1;

[0016] The desulfurization absorbent is selected from the desulfurization absorbent described in the first aspect of the present invention.

[0017] Through the above technical solutions, the desulfurization absorbent, desulfurization absorbent liquid and its application, and the method for desulfurizing sulfur-containing gases provided by the present invention achieve the following beneficial effects:

[0018] (1) The desulfurization absorbent contains a specific amount of organic guanidine and a specific amount of alcohol amine, which can form a synergistic effect and improve the desulfurization efficiency of the desulfurization absorbent.

[0019] (2) The organic base guanidine in the desulfurization absorbent has a specific structure. The desulfurization absorbent prepared by the guanidine, alcohol amine and water can effectively remove hydrogen sulfide and organic mercaptan from sulfur-containing gas and selectively remove carbon dioxide, thereby improving the selectivity and stability of the desulfurization absorbent.

[0020] (3) This desulfurization absorbent can be widely used in highly acidic environments and improve economic benefits. Detailed Implementation

[0021] The endpoints and any values ​​of the ranges disclosed herein 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 the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0022] The first aspect of the present invention provides a desulfurization absorbent, wherein, by weight, the desulfurization absorbent contains 1-20 parts by weight of an organic base guanidine and 10-70 parts by weight of an alcohol amine;

[0023] The organic base guanidine has the structure shown in Formula I:

[0024]

[0025] R1, R2, R3, R4, and R5 are each independently selected from hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted benzyl, or substituted or unsubstituted aromatic alkyl.

[0026] Alternatively, R5 may form a ring with R1 or R4, and / or R2 may form a ring with R3.

[0027] In this invention, the desulfurization absorbent contains the organic base guanidine and alcohol amine in the above-mentioned weight ratio, which enables the absorbent to improve desulfurization efficiency when applied in the field of desulfurization.

[0028] Furthermore, the desulfurization absorbent contains 5-15 parts by weight of an organic guanidine base and 20-60 parts by weight of an alcohol amine.

[0029] According to a preferred embodiment of the present invention, R1, R2, R3, R4, and R5 are each independently hydrogen, C1-C6 alkyl, or benzyl.

[0030] Alternatively, R5 forms a six-membered ring with R1 or R4, and R2 forms a six-membered ring with R3.

[0031] In this invention, the desulfurization absorbent contains a specific amount and structure of an organic guanidine base and a specific amount of an alkanolamine. These two components can form a synergistic effect, improving the desulfurization efficiency of the desulfurization absorbent solution made from this absorbent. Furthermore, by utilizing the structural tunability and structure-activity relationship of the organic guanidine compound, deep removal of various harmful gases from natural gas and selective removal of carbon dioxide are achieved. In addition, by introducing specific substituents into the organic guanidine molecule, it can be widely used in highly acidic environments and exhibits excellent selectivity and stability.

[0032] In this invention, it is important to note that when in contact with natural gas, the organic bases guanidine and alkanolamines react with hydrogen sulfide and organic sulfur compounds therein to form corresponding salts and aminosulfides. These reactions are highly selective because they are based on chemical affinity. Specifically, due to the different affinities between the various compounds, hydrogen sulfide and organic sulfur compounds can be selectively absorbed, while some carbon dioxide is retained.

[0033] The further selection of specific organic base guanidines is due to their excellent absorption performance and high stability. They possess different structures and electronic properties, allowing them to react with various types of organic sulfur compounds and hydrogen sulfide, thus improving the selectivity and efficiency of the desulfurization absorbent prepared from this desulfurization absorbent.

[0034] According to some preferred embodiments of the present invention, the organic base guanidine is selected from at least one of tetramethylguanidine, trimethylguanidine, dimethylguanidine, diphenylguanidine, 2-tert-butyl-1,1,3,3-tetramethylguanidine, 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene, and 1,5,7-triazabicyclo[4.4.0]dec-5-ene. The alkanolamine is selected from at least one of methyldiethanolamine, monoethanolamine, and diethanolamine.

[0035] The second aspect provides a desulfurization absorbent, wherein, based on the total amount of the absorbent, the absorbent comprises: 1-20 wt% of an organic base guanidine, 10-70 wt% of an alkanolamine, and 10-90 wt% of water;

[0036] The organic base guanidine has the structure shown in Formula I:

[0037]

[0038] R1, R2, R3, R4, and R5 are each independently selected from hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted benzyl, or substituted or unsubstituted aromatic alkyl, or R5 is cyclic with R1 or R4, and / or R2 is cyclic with R3.

[0039] In this invention, the desulfurization absorbent contains specific amounts of an organic guanidine base, a specific amount of an alkanolamine, and water, which can form a synergistic effect and improve the desulfurization efficiency of the absorbent. Furthermore, by utilizing the structural tunability and structure-activity relationship of the organic guanidine base compound, deep removal of various harmful gases from natural gas and selective removal of carbon dioxide are achieved. In addition, by introducing specific substituents into the organic guanidine molecule, it can be widely used in highly acidic environments and exhibits excellent selectivity and stability.

[0040] In this invention, it is important to note that when the desulfurization absorbent comes into contact with natural gas, the organic bases guanidine and alkanolamines therein react with hydrogen sulfide and organic sulfur compounds to form corresponding salts and aminosulfides. These reactions are highly selective because they are based on chemical affinity. Specifically, due to the different affinities between various compounds, hydrogen sulfide and organic sulfur compounds can be selectively absorbed while retaining some carbon dioxide. The specific range of guanidine and alkanolamine content in the desulfurization absorbent of this invention also contributes to achieving higher selectivity, thereby better controlling the absorption of different compounds during the desulfurization process.

[0041] Further selection of specific organic base guanidines is due to their excellent absorption performance and high stability. They possess different structures and electronic properties, allowing them to react with various types of organosulfur compounds and hydrogen sulfide, thus improving the selectivity and efficiency of the absorbent.

[0042] According to a preferred embodiment of the present invention, the absorbent comprises: 5-15 wt% of an organic base guanidine, 20-60 wt% of an alkanolamine and 30-80 wt% of water.

[0043] In this invention, the relationships between the components in the desulfurization absorbent further satisfy the above-mentioned range, enabling it to deeply absorb hydrogen sulfide and organic thiols while selectively retaining some carbon dioxide, thus meeting the current needs of natural gas desulfurization industrial applications.

[0044] According to the present invention, the viscosity of the absorbent at 25°C is 3-5 cp.

[0045] In this invention, the viscosity of the absorbent meets the above requirements, which is beneficial for absorbing acidic gases and meets the requirements of industrial applications. The inventors have found that when the viscosity is greater than 5 cp at 25°C, the contact between the absorbent and the gas and the mass transfer effect deteriorates.

[0046] According to a preferred embodiment of the present invention, R1, R2, R3, R4, and R5 are each independently hydrogen, C1-C6 alkyl, or benzyl, or R5 forms a six-membered ring with R1 or R4 and R2 forms a six-membered ring with R3.

[0047] According to the present invention, the organic base guanidine is selected from at least one of tetramethylguanidine, trimethylguanidine, dimethylguanidine, diphenylguanidine, 2-tert-butyl-1,1,3,3-tetramethylguanidine, 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene (MTBD) and 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD).

[0048] According to the present invention, the alkanolamine is selected from at least one of methyldiethanolamine, monoethanolamine and diethanolamine.

[0049] In this invention, the presence of an alkanolamine provides a proton source, while the organic base guanidine acts as a proton acceptor. This proton transfer reaction accelerates the reaction process and reduces side reactions. Furthermore, the specific amount and type of alkanolamine used in this invention are designed to achieve a synergistic effect with the organic base guanidine, thereby resulting in better absorption.

[0050] The second aspect of the present invention provides an application of the desulfurization absorbent described in the first aspect of the present invention in the desulfurization of sulfur-containing gases.

[0051] According to the present invention, the sulfur-containing gas is selected from at least one of natural gas, coalbed methane and oilfield gas.

[0052] A third aspect of the present invention provides a method for desulfurizing sulfur-containing gas, wherein the method includes: contacting and adsorbing the sulfur-containing gas and a desulfurization absorbent;

[0053] The gas-liquid ratio of the sulfur-containing gas to the desulfurization absorption liquid is 10-400:1;

[0054] The desulfurization absorbent is selected from the desulfurization absorbent described in the first aspect of the present invention.

[0055] In this invention, the gas-liquid ratio refers to the ratio of gas flow rate to liquid flow rate, wherein the units of gas flow rate and liquid flow rate are both L / h.

[0056] In this invention, the method utilizes a specific desulfurization absorbent, and further adjusting the gas-liquid ratio of the sulfur-containing gas to the absorbent is one of the keys to achieving deep selective desulfurization. This invention further adjusts the gas-liquid ratio of the sulfur-containing gas to the desulfurization absorbent to 10-400:1, which can better balance the selectivity and efficiency of the absorbent.

[0057] Furthermore, the gas-liquid ratio of the sulfur-containing gas to the desulfurization absorption liquid is 50-300:1, more preferably 100-200:1.

[0058] According to the present invention, the pressure of the sulfur-containing gas is 0.1-6 MPa.

[0059] In this invention, higher gas pressure can increase the solubility and mass transfer rate of hydrogen sulfide and organic sulfur, thereby improving absorption efficiency. However, excessively high gas pressure can lead to side effects such as a decrease in the bubble point of the absorbent and corrosion problems. Through extensive research, the inventors discovered that when the pressure of the sulfur-containing gas meets the above-mentioned range, the desulfurization absorbent can achieve a high removal efficiency of hydrogen sulfide and organic sulfur.

[0060] Furthermore, the pressure of the sulfur-containing gas is 0.2-5 MPa, more preferably 0.2-0.5 MPa.

[0061] According to the present invention, the sulfur-containing gas contains 0-20 vol% CO2, 0-10 vol% H2S, and 0-500 ppmv of organic thiols (calculated as S).

[0062] In this invention, the content of CO2, H2S, and organic thiols (calculated as S) in the sulfur-containing gas is not simultaneously zero. The remaining content of the sulfur-containing gas, besides CO2, H2S, and organic thiols (calculated as S), is N2.

[0063] In this invention, the carbon dioxide content affects the acidity / alkalinity and absorption capacity of the absorbent. A higher carbon dioxide content can lower the pH of the absorbent, thereby improving absorption capacity and selectivity. However, excessively high carbon dioxide content can lead to increased corrosivity of the absorbent and absorption of other components such as ammonia. Through extensive research, the inventors have discovered that when the CO2 content in the sulfur-containing gas meets the aforementioned range, it can work in conjunction with the specific pressure of the sulfur-containing gas to achieve high removal efficiency of hydrogen sulfide and organic sulfur while maintaining high selectivity.

[0064] According to a particularly preferred embodiment of the present invention, the CO2 content in the sulfur-containing gas is 5-15 wt%.

[0065] In this invention, when the carbon dioxide content is low, the desulfurization absorbent exhibits high efficiency in removing hydrogen sulfide and organic sulfur, while also being relatively low in cost and easy to prepare. According to a particularly preferred embodiment of the invention, when the CO2 content in the sulfur-containing gas is 2-3 wt%, the desulfurization absorbent can achieve complete removal of organic sulfur, while the removal rate of hydrogen sulfide can also reach over 99%. Selectively removing a portion of carbon dioxide can reduce the cost and energy consumption of the purification process while meeting natural gas quality requirements, thereby improving purification efficiency and economic benefits.

[0066] According to one embodiment of the present invention, the sulfur-containing gas contains 0-10 vol% H2S and 0-500 ppmv of organic thiols (calculated as S), and the contents of CO2, H2S and organic thiols (calculated as S) are not simultaneously 0.

[0067] In this invention, using the method of this invention, the desulfurization absorbent has a hydrogen sulfide removal rate of ≥99%, a methanethiol removal rate of ≥98%, and a CO2 removal rate of 97-100%.

[0068] According to a specific embodiment of the present invention, the main apparatus for desulfurization of sulfur-containing gas includes an absorption tower, a regeneration tower, a flash tank, a lean-rich liquid heat exchanger, a lean liquid pump, and a rich liquid pump. Sulfur-containing gas enters from the bottom of the absorption tower and comes into countercurrent contact with the desulfurization absorbent sprayed from the top of the absorption tower. Acidic gases in the sulfur-containing gas are absorbed, and the purified gas is discharged from the top of the absorption tower and sent to the next process. The rich liquid, having absorbed the acidic gases, flows into the flash tank under the high pressure of natural gas or the pressure of a pump, where dissolved gases are flashed out. This flash tank is not mandatory and can be installed depending on the absorption pressure and material composition. Subsequently, the rich liquid enters the lean-rich liquid heat exchanger to exchange heat with the lean liquid. It then enters from the top of the regeneration tower and comes into countercurrent contact with the upward-flowing stripping steam, regenerating the desulfurization absorbent. The lean liquid flows out from the bottom of the regeneration tower, enters the lean-rich liquid heat exchanger to exchange heat with the rich liquid, and is then pressurized by the lean liquid pump and sent to the lean liquid cooler for cooling before being recycled from the top of the absorption tower.

[0069] The present invention will be described in detail below through embodiments.

[0070] In the following examples and comparative examples, the content of each component in the sulfur-containing gas was determined by coulometric analysis and chromatographic methods;

[0071] In the examples and comparative examples, all raw materials used were commercially available products.

[0072] Unless otherwise specified, the raw gas in the examples and comparative examples is sulfur-containing natural gas.

[0073] Example 1

[0074] The feed gas pressure was 0.5 MPa, the room temperature (25℃) temperature was 25℃, the H2S content was 4.5 vol%, the CO2 content was 5.5 vol%, the CH3SH content was 100 ppmv, the C2H5SH content was 50 ppmv, and the remainder was N2. The desulfurization absorbent consisted of 45 g of methyldiethanolamine, 5 g of tetramethylguanidine, and the remainder was water (50 g). The viscosity of the absorbent at 25℃ was 3.24 cp. Under a gas-liquid ratio of 150:1, the H2S content in the purified gas was 4.3 mg / m³. 3 The CH3SH content was 1.6 mg / m³. 3 The C2H5SH content was 0.8 mg / m³. 3 The total sulfur content is 6.8 mg / m³. 3 The CO2 content was 1.1 vol%.

[0075] Example 2

[0076] The method was followed in Example 1, except that the gas-liquid ratio was 100:1. The final purified gas contained 1.4 mg / m³ of H₂S. 3 The CH3SH content was 1.2 mg / m³. 3 The C2H5SH content was 1.3 mg / m³. 3 The total sulfur content is 3.6 mg / m³. 3 The CO2 content is 0.5 vol%. The viscosity of the absorbent at 25°C is 3.24 cp.

[0077] Example 3

[0078] The method was followed in Example 1, except that the gas-liquid ratio was 200:1. The final purified gas contained 7.5 mg / m³ of H₂S. 3 The CH3SH content was 1.7 mg / m³. 3 The C2H5SH content is 1.0 mg / m³. 3 The total sulfur content is 10.2 mg / m³. 3 The CO2 content is 1.9 vol%. The viscosity of the absorbent at 25°C is 3.24 cp.

[0079] Example 4

[0080] The method was followed in Example 1, except that 5g of tetramethylguanidine was replaced with 5g of dimethylguanidine. The final H2S content in the purified gas was 4.2 mg / m³. 3 The CH3SH content was 1.3 mg / m³. 3 The C2H5SH content was 0.7 mg / m³. 3 The total sulfur content is 6.2 mg / m³. 3 The CO2 content is 0 vol%. The viscosity of the absorbent at 25°C is 3.42 cp.

[0081] Example 5

[0082] The method was followed in Example 1, except that 5g of tetramethylguanidine was replaced with 5g of trimethylguanidine. The final H2S content in the purified gas was 4.2 mg / m³. 3 The CH3SH content was 1.4 mg / m³. 3 The C2H5SH content was 0.8 mg / m³. 3 The total sulfur content is 6.4 mg / m³. 3 The CO2 content is 0.2 vol%. The viscosity of the absorbent at 25°C is 3.42 cp.

[0083] Example 6

[0084] The method was followed in Example 1, except that 5g of tetramethylguanidine was replaced with 5g of MTBD. The final H2S content in the purified gas was 3.6mg / m³. 3 The CH3SH content was 7.9 mg / m³. 3 The C2H5SH content was 5.0 mg / m³. 3 The total sulfur content is 16.5 mg / m³. 3 The CO2 content is 0 vol%. The viscosity of the absorbent at 25°C is 3.50 cp.

[0085] Example 7

[0086] The method was followed in Example 1, except that 5g of tetramethylguanidine was replaced with 5g of TBD. The final purified gas contained 3.7mg / m³ of H₂S. 3 The CH3SH content was 7.9 mg / m³. 3 The C2H5SH content was 5.3 mg / m³. 3 The total sulfur content is 16.9 mg / m³. 3 The CO2 content is 0 vol%. The viscosity of the absorbent at 25°C is 3.48 cp.

[0087] Example 8

[0088] The method was followed in Example 1, except that 5g of tetramethylguanidine was replaced with 5g of diphenylguanidine. The final H2S content in the purified gas was 17.6 mg / m³. 3 The CH3SH content was 27.0 mg / m³. 3 The C2H5SH content was 15.3 mg / m³. 3 The total sulfur content is 59.9 mg / m³. 3 The CO2 content is 1.5 vol%. The viscosity of the absorbent at 25°C is 3.50 cp.

[0089] Example 9

[0090] The method was followed in Example 1, except that 5g of tetramethylguanidine was replaced with 5g of 2-tert-butyl-1,1,3,3-tetramethylguanidine. The final H2S content in the purified gas was 4mg / m³. 3 The CH3SH content was 1.7 mg / m³. 3 The C2H5SH content was 0.9 mg / m³. 3 The total sulfur content is 6.7 mg / m³. 3 The CO2 content is 1.3 vol%. The viscosity of the absorbent at 25°C is 3.46 cp.

[0091] Example 10

[0092] The method was followed in Example 1, except that 5g of tetramethylguanidine was replaced with 5g of methylguanidine, resulting in a final H2S content of 4.3mg / m³ in the purified gas. 3 The CH3SH content was 1.3 mg / m³. 3 The C2H5SH content was 1.2 mg / m³. 3 The total sulfur content is 6.9 mg / m³. 3 The CO2 content is 0 vol%. The viscosity of the absorbent at 25°C is 3.18 cp.

[0093] Example 11

[0094] The method was followed in Example 1, except that 45g of methyldiethanolamine was replaced with 45g of diethanolamine, resulting in a final H2S content of 8.0 mg / m³ in the purified gas. 3 The CH3SH content was 17.2 mg / m³. 3 The C2H5SH content was 12.7 mg / m³. 3 The total sulfur content is 27.9 mg / m³. 3 The CO2 content is 0.1 vol%. The viscosity of the absorbent at 25°C is 3.24 cp.

[0095] Example 12

[0096] The method was followed in Example 1, except that 45g of methyldiethanolamine was replaced with 45g of monoethanolamine, resulting in a final H2S content of 7.9mg / m³ in the purified gas. 3 The CH3SH content was 15.9 mg / m³. 3 The C2H5SH content was 11.3 mg / m³. 3 The total sulfur content is 35.1 mg / m³. 3 The CO2 content is 0 vol%. The viscosity of the absorbent at 25°C is 3.24 cp.

[0097] Example 13

[0098] The method was followed in Example 1, except that the absorbent consisted of 20g of methyldiethanolamine, 5g of tetramethylguanidine, and 75g of water. The final purified gas contained 21mg / m³ of H₂S. 3 The CH3SH content was 2.1 mg / m³. 3 The C2H5SH content was 1.3 mg / m³. 3 The total sulfur content is 24.5 mg / m³. 3 The CO2 content is 2.8 vol%. The viscosity of the absorbent at 25°C is 2.59 cp.

[0099] Example 14

[0100] The method was followed in Example 1, except that the absorbent consisted of 60g of methyldiethanolamine, 5g of tetramethylguanidine, and 35g of water. The final purified gas contained 3.7mg / m³ of H₂S. 3 The CH3SH content was 1.5 mg / m³. 3 The C2H5SH content was 0.8 mg / m³. 3 The total sulfur content is 6.0 mg / m³. 3 The CO2 content is 0.8 vol%. The viscosity of the absorbent at 25°C is 3.95 cp.

[0101] Example 15

[0102] The method was followed in Example 1, except that the absorbent composition was: 45g of methyldiethanolamine, 1g of tetramethylguanidine, and 54g of water. The final purified gas contained 13.5 mg / m³ of H₂S. 3 The CH3SH content was 12.9 mg / m³. 3 The C2H5SH content was 11.7 mg / m³. 3 The total sulfur content is 38 mg / m³. 3 The CO2 content is 2.1 vol%. The viscosity of the absorbent at 25°C is 3.22 cp.

[0103] Example 16

[0104] The method was followed in Example 1, except that the absorbent consisted of 45g of methyldiethanolamine, 10g of tetramethylguanidine, and 45g of water. The final purified gas contained 3.6mg / m³ of H₂S. 3 The CH3SH content was 0.8 mg / m³. 3 The C2H5SH content is 0.5 mg / m³. 3 The total sulfur content is 5.0 mg / m³. 3 The CO2 content is 0.8 vol%. The viscosity of the absorbent at 25°C is 3.30 cp.

[0105] Example 17

[0106] The method was followed in Example 1, except that the pressure of the raw gas was 6 MPa. The final purified gas contained 2.1 mg / m³ of H₂S. 3 The CH3SH content was 0.9 mg / m³. 3 The C2H5SH content was 0.9 mg / m³. 3 The total sulfur content is 3.9 mg / m³. 3 The CO2 content is 0.2 vol%. The viscosity of the absorbent at 25°C is 3.24 cp.

[0107] Example 18

[0108] The method was followed in Example 1, except that the feed gas contained 4.5% H2S, 10% CO2, 100 ppmv CH3SH, 50 ppmv C2H5SH, and the remainder was N2. The final purified gas contained 5.1 mg / m³ of H2S. 3 The CH3SH content was 1.7 mg / m³. 3 The C2H5SH content is 1 mg / m³. 3 The total sulfur content is 7.9 mg / m³. 3 The CO2 content is 3.3 vol%. The viscosity of the absorbent at 25°C is 3.24 cp.

[0109] Comparative Example 1

[0110] The method was followed in Example 1, except that 5g of tetramethylguanidine was replaced with 5g of N-acetylguanidine. The final H2S content in the purified gas was 24.1 mg / m³. 3 The CH3SH content was 61.2 mg / m³. 3 The C2H5SH content was 33.7 mg / m³. 3 The total sulfur content is 119.0 mg / m³. 3 The CO2 content is 2.2 vol%. The viscosity of the absorbent at 25°C is 4.55 cp.

[0111] Comparative Example 2

[0112] The method was followed in Example 1, except that the absorbent consisted of 65g of methyldiethanolamine, 10g of tetramethylguanidine, and 25g of water. The final purified gas contained 5.2mg / m³ of H₂S. 3 The CH3SH content was 1.9 mg / m³. 3 The C2H5SH content was 1.1 mg / m³. 3 The total sulfur content is 8.2 mg / m³. 3 The CO2 content is 1.8 vol%. The viscosity of the absorbent at 25°C is 4.12 cp.

[0113] Comparative Example 3

[0114] The method was followed in Example 1, except that the gas-liquid ratio of the feed gas and the desulfurization absorbent was 250:1. The final purified gas contained 10.6 mg / m³ of H₂S. 3 The CH3SH content was 3.4 mg / m³. 3 The C2H5SH content was 1.9 mg / m³. 3 The total sulfur content is 15.9 mg / m³. 3The CO2 content is 2.4 vol%. The viscosity of the absorbent at 25°C is 3.24 cp.

[0115] The results above show that the organic guanidines with different substituents in Examples 1-18 of the present invention have good purification effects on hydrogen sulfide and thiols in sulfur-containing gases. Among them, for the preferred tetramethylguanidine, the higher its content within a certain range, the better the purification effect, and tetramethylguanidine has better selectivity for the removal of sulfur-containing compounds and carbon dioxide.

[0116] In Comparative Example 1, when the guanidine molecule contains an amide group, it reduces the basicity of the organic amine, thus affecting the absorption of thiols. When the guanidine substituted group is a benzene ring, the steric shielding effect also affects the absorption of hydrogen sulfide, thiols, and carbon dioxide.

[0117] In Comparative Example 3, the concentration of organic amine was too high, which led to an increase in solution viscosity and a decrease in mass transfer efficiency.

[0118] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A desulfurization absorbent, characterized in that, Based on the total amount of the desulfurization absorbent, the desulfurization absorbent comprises: 1-10 wt% of an organic guanidine base, 20-60 wt% of an alkanolamine, and 35-75 wt% of water; wherein the organic guanidine base has the structure shown in Formula I: Formula I, wherein R1, R2, R3, R4, and R5 are each independently selected from hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted benzyl, or substituted or unsubstituted aromatic alkyl; or R5 is cyclic with R1 or R4, and / or R2 is cyclic with R3.

2. The desulfurization absorbent according to claim 1, wherein, The viscosity of the absorbent at 25°C is 3-5 cp.

3. The desulfurization absorbent according to claim 1, wherein, The organic base guanidine is selected from at least one of tetramethylguanidine, trimethylguanidine, dimethylguanidine, diphenylguanidine, 2-tert-butyl-1,1,3,3-tetramethylguanidine, 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene and 1,5,7-triazabicyclo[4.4.0]dec-5-ene.

4. The desulfurization absorbent according to claim 1, wherein, The alkanolamine is selected from at least one of methyldiethanolamine, monoethanolamine, and diethanolamine.

5. The application of the desulfurization absorbent according to any one of claims 1-4 in the desulfurization of sulfur-containing gases.

6. The application according to claim 5, wherein, The sulfur-containing gas is selected from at least one of natural gas, coalbed methane, and oilfield gas.

7. A method for desulfurizing sulfur-containing gas, characterized in that, The method includes: contacting and absorbing sulfur-containing gas and desulfurization absorbent; the gas-liquid ratio of the sulfur-containing gas and the desulfurization absorbent is 10-400:1; wherein the desulfurization absorbent is selected from the desulfurization absorbent described in any one of claims 1-4.

8. The method according to claim 7, wherein, The gas-liquid ratio of the sulfur-containing gas to the desulfurization absorption liquid is 50-300:

1.

9. The method according to claim 8, wherein, The gas-liquid ratio of the sulfur-containing gas to the desulfurization absorption liquid is 100-200:

1.

10. The method according to claim 7, wherein, The pressure of the sulfur-containing gas is 0.1-6 MPa.

11. The method according to claim 10, wherein, The pressure of the sulfur-containing gas is 0.2-5 MPa.

12. The method according to claim 7, wherein, The sulfur-containing gas contains 0-20 vol% CO2, 0-10 vol% H2S, and 0-500 ppmv of organic thiols (calculated as S), and the contents of CO2, H2S, and organic thiols (calculated as S) are not all 0 at the same time.

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