Desulfurization absorbent, desulfurization absorption liquid and application thereof, and sulfur-containing gas desulfurization method

Abstract

The invention relates to the field of gas purification, and discloses a desulfurization absorbent which comprises the following components in parts by weight: 1-20 parts of organic alkali guanidine and 10-70 parts of alcohol amine. The organic alkali guanidine has a structure as shown in a formula I: # imgabs0 #, wherein R1, R2, R3, R4 and R5 are respectively and independently selected from hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted benzyl, or substituted or unsubstituted aromatic alkyl; or R5 and R1 or R4 form a ring, and / or R2 and R3 form a ring. The desulfurization absorbent contains a specific content of organic alkali guanidine and a specific content of alcohol amine, so that a synergistic effect can be formed, and the desulfurization efficiency of the desulfurization absorption liquid is improved. Besides, the organic alkali guanidine has a specific structure, so that various harmful gases in the sulfur-containing gas can be effectively removed, the contained carbon dioxide can be selectively removed, and the selectivity and the stability of the desulfurization absorption liquid are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of gas purification, and in particular to a desulfurization absorbent, a desulfurization absorption liquid and its application, a method for desulfurizing sulfur-containing gas, an organic amine absorption liquid for deep desulfurization of hydrogen sulfide and mercaptan and its application, and can selectively remove carbon dioxide. Background Art

[0002] In recent years, the limit on total sulfur content in natural gas has been further reduced, with the total sulfur limit of Class I natural gas rising from 60 mg / m 3 Reduced to 20 mg / m 3 The total sulfur limit of Class II natural gas is 200 mg / m 3 Reduced to 100 mg / m 3 . The improvement of natural gas quality standards has brought more stringent challenges to the removal of organic sulfur (such as methyl mercaptan, ethyl mercaptan, etc.) in highly acidic and organic sulfur-containing production areas and enterprises. Therefore, deep desulfurization is to meet higher standards of natural gas quality requirements, and also to reduce environmental pollution and protect the safe operation of equipment. However, the removal efficiency of organic mercaptans using traditional amine absorption liquid formulations and devices is very low. Organic guanidine compounds are a class of polyamine compounds that are widely present in nature. They are commonly found in natural products such as nucleic acids and proteins, and even in humans and animals. There are trace amounts of organic guanidine compounds. Due to its unique properties as an organic base in the field of chemistry and catalysis, organic guanidine has received widespread attention and is often used as a catalyst, associating agent, etc. The alkalinity of organic guanidine enables it to absorb weakly acidic mercaptans, so it can achieve the effect of deep desulfurization. However, due to the large number of organic guanidine compounds, it is necessary to screen to find a suitable desulfurizer, and considerations such as selectivity also increase the difficulty of the process. Summary of the invention

[0003] The purpose of the present invention is to overcome the problems of incomplete desulfurization of sulfur-containing gas and difficulty in removing organic mercaptan in the prior art, and to provide a desulfurization absorbent, a desulfurization absorption liquid and its application, and a method for desulfurization of sulfur-containing gas. The desulfurization absorbent contains a specific content of organic base guanidine and a specific content of alcohol amine, which can form a synergistic effect and improve the desulfurization efficiency of the desulfurization absorption liquid. In addition, the organic base guanidine has a specific structure, which can effectively remove multiple harmful gases in the sulfur-containing gas and selectively remove the contained carbon dioxide, thereby improving the selectivity and stability of the desulfurization absorption liquid.

[0004] In order to achieve the above object, the first aspect of the present invention provides a desulfurization absorbent, which 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 a structure shown in Formula I:

[0006]

[0007] 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;

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

[0009] The second aspect of the present invention provides a desulfurization absorption liquid, wherein, based on the total amount of the absorption liquid, the absorption liquid comprises: 1-20 wt% of organic base guanidine, 10-70 wt% of alcohol amine and 10-90 wt% of water;

[0010] Wherein, the organic base guanidine has a structure shown in Formula I:

[0011]

[0012] 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 forms a ring with R1 or R4, and / or R2 forms a ring with R3.

[0013] The third aspect of the present invention provides a use of the desulfurization absorbent described in the first aspect of the present invention or the desulfurization absorption liquid described in the second aspect of the present invention in the desulfurization of sulfur-containing gas.

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

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

[0016] Wherein, the desulfurization absorption liquid is selected from the desulfurization absorption liquid described in the first aspect of the present invention.

[0017] Through the above technical scheme, the desulfurization absorbent, desulfurization absorption liquid and application, and the method for desulfurization of sulfur-containing gas provided by the present invention achieve the following beneficial effects:

[0018] (1) The desulfurization absorbent contains a specific content of organic base guanidine and a specific content 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 organic base guanidine, alcohol amine and water can effectively remove hydrogen sulfide and organic mercaptans in sulfur-containing gas and selectively remove the carbon dioxide contained therein, thereby improving the selectivity and stability of the desulfurization absorbent.

[0020] (3) The desulfurization absorption liquid can be widely used in highly acidic environments and improve certain economic benefits. DETAILED DESCRIPTION

[0021] 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.

[0022] The first aspect of the present invention provides a desulfurization absorbent, which 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 a structure shown in Formula I:

[0024]

[0025] 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;

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

[0027] In the present invention, the desulfurization absorbent contains the organic base guanidine and alcohol amine in the above-mentioned weight ratio, so that the absorbent can improve the desulfurization efficiency when applied to the desulfurization field.

[0028] Furthermore, the desulfurization absorbent contains 5-15 parts by weight of organic base guanidine and 20-60 parts by weight of 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 the present invention, the desulfurization absorbent contains a specific content and a specific structure of organic base guanidine and a specific content of alcohol amine, which can form a synergistic effect and improve the desulfurization efficiency of the desulfurization absorption liquid made by the desulfurization absorbent. Further, by utilizing the structural adjustability and structure-activity relationship of the organic base guanidine compound, the deep removal of various harmful gases in natural gas and the selective removal of carbon dioxide are achieved. In addition, by introducing specific substituents into the organic guanidine molecule, it is widely used in highly acidic environments and has excellent selectivity and stability.

[0032] In the present invention, it should be noted that when in contact with natural gas, the organic bases guanidine and alcohol amine react with the hydrogen sulfide and organic sulfur compounds therein to form corresponding salts and amino sulfides. 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, and part of the carbon dioxide can be retained.

[0033] The specific organic base guanidine is further selected because they have good absorption performance and high stability. They have different structures and electronic properties, so they can react with different types of organic sulfur compounds and hydrogen sulfide, improving the selectivity and efficiency of the desulfurization absorption liquid prepared by the 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 alcoholamine is selected from at least one of methyldiethanolamine, monoethanolamine and diethanolamine.

[0035] A second aspect provides a desulfurization absorption liquid, wherein, based on the total amount of the absorption liquid, the absorption liquid comprises: 1-20 wt% of organic base guanidine, 10-70 wt% of alcohol amine and 10-90 wt% of water;

[0036] Wherein, the organic base guanidine has a structure shown in Formula I:

[0037]

[0038] 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 forms a ring with R1 or R4, and / or R2 forms a ring with R3.

[0039] In the present invention, the desulfurization absorption liquid contains a specific content of organic base guanidine and a specific content of alcohol amine and water, which can form a synergistic effect and improve the desulfurization efficiency of the desulfurization absorption liquid. Further, by utilizing the structural adjustability and structure-activity relationship of the organic base guanidine compound, the deep removal of various harmful gases in natural gas and the selective removal of carbon dioxide are achieved. In addition, by introducing specific substituents into the organic guanidine molecule, it is widely used in highly acidic environments and has excellent selectivity and stability.

[0040] In the present invention, it should be noted that when the desulfurization absorption liquid contacts natural gas, the organic base guanidine and alcohol amine therein react with the hydrogen sulfide and organic sulfur compounds therein to form corresponding salts and amino sulfides. 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, and part of the carbon dioxide can be retained. In the desulfurization absorption liquid described in the present invention, the content range of specific organic base guanidine and alcohol amine also helps to achieve higher selectivity, thereby better controlling the absorption of different compounds during the desulfurization process.

[0041] The specific organic base guanidines are further selected because they have good absorption properties and high stability. They have different structures and electronic properties, so they can react with different types of organic sulfur compounds and hydrogen sulfide, improving the selectivity and efficiency of the absorption liquid.

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

[0043] In the present invention, the relationship between the components in the desulfurization absorption liquid further meets the above range, and can have the characteristics of deeply absorbing hydrogen sulfide and organic sulfur mercaptans while selectively retaining part of carbon dioxide, so as to meet the current needs of natural gas desulfurization industrial applications.

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

[0045] In the present invention, the viscosity of the absorption liquid meets the above requirements, can be conducive to absorbing acidic gases, and meets the requirements of industrial applications. The inventors have found that when the viscosity is greater than 5cp at 25°C, the contact between the absorption liquid and the gas and the mass transfer effect will deteriorate.

[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 alcoholamine is selected from at least one of methyldiethanolamine, monoethanolamine and diethanolamine.

[0049] In the present invention, the presence of the alcohol amine can provide a proton source, while the organic base guanidine can serve as a proton acceptor. This proton transfer reaction can accelerate the reaction and reduce the occurrence of side reactions. The amount and type of the alcohol amine are further limited in the present invention in order to achieve a synergistic effect with the organic base guanidine, thereby achieving a better absorption effect.

[0050] The second aspect of the present invention provides a use of the desulfurization absorption liquid described in the first aspect of the present invention in the desulfurization of sulfur-containing gas.

[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] The third aspect of the present invention provides a method for desulfurizing sulfur-containing gas, wherein the method comprises: contacting and adsorbing the sulfur-containing gas and a desulfurization absorption liquid;

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

[0054] Wherein, the desulfurization absorption liquid is selected from the desulfurization absorption liquid described in the first aspect of the present invention.

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

[0056] In the present invention, the method uses a specific desulfurization absorption liquid, and further adjusts the gas-liquid ratio of the sulfur-containing gas to the absorption liquid, which is one of the keys to achieve deep selective desulfurization. The present invention further adjusts the gas-liquid ratio of the sulfur-containing gas to the desulfurization absorption liquid to 10-400:1, which can better balance the selectivity and efficiency of the absorption liquid.

[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 the present invention, a higher gas pressure can increase the solubility and mass transfer rate of hydrogen sulfide and organic sulfur, thereby improving the absorption efficiency. However, too high a gas pressure can lead to side effects such as a decrease in the bubble point of the absorption liquid and corrosion problems. After extensive research by the inventors, it was found that when the pressure of the sulfur-containing gas meets the above range, the desulfurization absorption liquid can achieve a higher 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 mercaptan in terms of S.

[0062] In the present invention, in the sulfur-containing gas, the contents of CO2, H2S and organic mercaptan calculated as S are not all 0. In the sulfur-containing gas, in addition to CO2, H2S and organic mercaptan calculated as S, the remainder is N2.

[0063] In the present invention, the carbon dioxide content has an impact on the acidity and alkalinity, absorption capacity and other properties of the absorption liquid. A higher carbon dioxide content can reduce the pH value of the absorption liquid, thereby improving the absorption capacity and selectivity. However, too high a carbon dioxide content can lead to problems such as increased corrosiveness of the absorption liquid and absorption of other components such as ammonia. After extensive research by the inventors, it was found that when the content of CO2 in the sulfur-containing gas meets the above range, it can cooperate with the specific pressure of the above sulfur-containing gas to achieve a higher removal efficiency of hydrogen sulfide and organic sulfur while maintaining a higher selectivity.

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

[0065] In the present invention, when the carbon dioxide content is low, the desulfurization absorption liquid has a high efficiency in removing hydrogen sulfide and organic sulfur, and its cost is relatively low and it is easy to prepare. According to a particularly preferred embodiment of the present invention, when the content of CO2 in the sulfur-containing gas is 2-3wt%, the desulfurization absorption liquid can achieve the effect of completely removing organic sulfur, and the removal rate of hydrogen sulfide can also reach more than 99%. Selectively removing part of the carbon dioxide can reduce the cost and energy consumption of the purification process while meeting the quality requirements of natural gas, and improve the 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 mercaptan calculated as S, and the contents of CO2, H2S and organic mercaptan calculated as S are not 0 at the same time.

[0067] In the present invention, by using the method of the present invention, the removal rate of hydrogen sulfide by the desulfurization absorption liquid is ≥99%, the removal rate of methyl mercaptan is ≥98%, and the removal rate of CO2 by the desulfurization absorption liquid is 97-100%.

[0068] According to a specific embodiment of the present invention, the main devices of the desulfurization process of sulfur-containing gas include an absorption tower, a regeneration tower, a flash tank, a lean-rich liquid heat exchanger, a lean liquid pump, and a rich liquid pump. The sulfur-containing gas enters from the bottom of the absorption tower and contacts with the desulfurization absorption liquid sprayed from the top of the absorption tower in countercurrent. The acidic gas in the sulfur-containing gas is absorbed, and the purified gas is discharged from the top of the absorption tower and sent to the next process. The rich liquid that has absorbed the acidic gas is sent to the flash tank under the high pressure of natural gas or the pressure of the pump to flash out the dissolved gas. The flash tank in this step is not necessary and can be set according to the absorption pressure and material composition. The rich liquid then enters the lean-rich liquid heat exchanger to exchange heat with the lean liquid, enters from the top of the regeneration tower, and contacts with the gas stripping steam from the bottom to the top in countercurrent to regenerate the desulfurization absorption liquid. 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 then is pressurized by the lean liquid pump and sent to the lean liquid cooler for cooling, and then enters from the upper part of the absorption tower for recycling.

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

[0070] In the following examples and comparative examples, the content of each component in the sulfur-containing gas was measured by coulometer and chromatography;

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

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

[0073] Example 1

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

[0075] Example 2

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

[0077] Example 3

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

[0079] Example 4

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

[0081] Example 5

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

[0083] Example 6

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

[0085] Example 7

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

[0087] Example 8

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

[0089] Example 9

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

[0091] Example 10

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

[0093] Embodiment 11

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

[0095] Example 12

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

[0097] Example 13

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

[0099] Embodiment 14

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

[0101] Embodiment 15

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

[0103] Example 16

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

[0105] Embodiment 17

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

[0107] Embodiment 18

[0108] The method of Example 1 is the same, except that the H2S content in the raw gas is 4.5%, the CO2 content is 10%, the CH3SH content is 100ppmv, the C2H5SH content is 50ppmv, and the rest is N2. The H2S content in the final purified gas is 5.1mg / m 3 , CH3SH content is 1.7mg / m 3 , C2H5SH content is 1mg / m 3 , the total sulfur content is 7.9mg / m 3 , CO2 content is 3.3 vol%. The viscosity of the absorption liquid at 25°C is 3.24 cp.

[0109] Comparative Example 1

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

[0111] Comparative Example 2

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

[0113] Comparative Example 3

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

[0115] From the above results, it can be seen that the organic base guanidine with different substituents in Examples 1-18 of the technical solution of the present invention has a good effect on the purification of hydrogen sulfide and mercaptans in sulfur-containing gas. 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, the alkalinity of the organic amine is reduced, thereby affecting the absorption of thiols. When the substituent on the guanidine is a benzene ring, the absorption of hydrogen sulfide, thiols, and carbon dioxide acidic gases is also affected due to the steric shielding effect.

[0117] In Comparative Example 3, the concentration of the organic amine was too high, resulting in an increase in the solution viscosity and a deterioration in the mass transfer effect.

[0118] 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 desulfurization absorbent, characterized in that: In parts by weight, the desulfurization absorbent contains 1-20 parts by weight of organic base guanidine and 10-70 parts by weight of alcohol amine; The organic base guanidine has a structure shown in 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; Alternatively, R5 forms a ring with R1 or R4, and / or R2 forms a ring with R3.

2. The absorbent according to claim 1, wherein In parts by weight, the desulfurization absorbent contains 5-15 parts by weight of organic base guanidine and 20-60 parts by weight of alcohol amine.

3. A desulfurization absorption liquid, characterized in that: Based on the total amount of the desulfurization absorption liquid, the desulfurization absorption liquid comprises: 1-20wt% of organic base guanidine, 10-70wt% of alcohol amine and 10-90wt% of water; Wherein, the organic base guanidine has a structure shown in 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; Alternatively, R5 forms a ring with R1 or R4, and / or R2 forms a ring with R3.

4. The desulfurization absorption liquid according to claim 3, wherein: The absorption liquid comprises: 5-15 wt% of organic base guanidine, 20-60 wt% of alcohol amine and 30-80 wt% of water; Preferably, the viscosity of the absorption liquid at 25° C. is 3-5 cp.

5. The desulfurization absorption liquid according to claim 3 or 4, wherein: R1, R2, R3, R4, and R5 are each independently hydrogen, C1-C6 alkyl, or benzyl; Alternatively, R5 forms a six-membered ring with R1 or R4 and R2 forms a six-membered ring with R3.

6. The desulfurization absorption liquid according to any one of claims 3 to 5, 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.

7. The desulfurization absorption liquid according to any one of claims 3 to 6, wherein: The alcoholamine is selected from at least one of methyldiethanolamine, monoethanolamine and diethanolamine.

8. Use of the desulfurization absorbent according to claim 1 or 2 or the desulfurization absorption liquid according to any one of claims 3 to 7 in the desulfurization of sulfur-containing gas.

9. The use according to claim 8, wherein: The sulfur-containing gas is selected from at least one of natural gas, coal-bed methane and oilfield gas.

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

11. The method according to claim 10, wherein: The gas-liquid ratio of the sulfur-containing gas to the desulfurization absorption liquid is 50-300:1, more preferably 100-200:

1.

12. The method according to claim 10 or 11, wherein: The pressure of the sulfur-containing gas is 0.1-6 MPa, preferably 0.2-5 MPa; Preferably, the sulfur-containing gas contains 0-20 vol% CO2, 0-10 vol% H2S and an organic mercaptan content calculated as S of 0-500 ppmv, and the contents of CO2, H2S and organic mercaptan calculated as S are not 0 at the same time.

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