A method for removing hydrogen sulfide gas using an iron-containing ionic liquid

Abstract

This invention proposes a method for removing hydrogen sulfide gas using an iron-containing coordination ionic liquid. The invention utilizes an iron-containing coordination ionic liquid with a large molar volume as a desulfurizing agent to absorb H2S and oxidize it into elemental sulfur, thus achieving gas desulfurization and purification. After the elemental sulfur is recovered, air or oxygen is introduced into the reacted ionic liquid to allow for regeneration and recycling. Compared with traditional desulfurization methods, this process causes almost no loss of absorbent, has high H2S solubility and strong H2S oxidizing capacity, and does not involve side reactions during absorption, resulting in minimal secondary pollution. It overcomes the problems of excessive byproduct salts and easy pollution associated with traditional desulfurization processes, and has excellent development prospects in the field of industrial gas purification.

Description

Technical Field

[0001] This invention relates to the field of gas purification technology, specifically to the preparation of an iron-containing coordination ionic liquid and its application in removing hydrogen sulfide from gases. More specifically, it relates to a method for removing hydrogen sulfide gas using an iron-containing coordination ionic liquid. In this desulfurization method, this type of ionic liquid desulfurizing agent is pollution-free, has no side reactions, achieves a high desulfurization rate, and can be recycled after regeneration, making it a novel, green, and environmentally friendly hydrogen sulfide removal process. Technical Background

[0002] Hydrogen sulfide is a colorless, acidic gas with a pungent, rotten egg odor. It is a type of foul-smelling pollutant that can affect human health, even causing death in severe cases; it contributes to acid rain, damaging agricultural production; it can poison and deactivate catalysts, corrode pipes and equipment, and lead to reduced quality and quantity in industrial production. Therefore, removing hydrogen sulfide from the environment and industrial production is an urgent problem that needs to be solved, considering human health, environmental protection, and the development of industry and agriculture.

[0003] There are many methods for gas desulfurization in industry. Based on the physicochemical form of the desulfurizing agent during the desulfurization process, current desulfurization technologies can be broadly classified into two categories: dry desulfurization and wet desulfurization. Dry desulfurization has a slow desulfurization rate, low desulfurization efficiency, large desulfurizing agent consumption, large equipment size, and the desulfurizing agent is not easy to regenerate. It is suitable for applications with low sulfur content. Wet desulfurization is a gas-liquid reaction, with a fast desulfurization reaction rate, high desulfurization rate, and high precision. The desulfurizing agent is easy to regenerate. Its disadvantages are a larger initial investment, higher energy consumption, and it is suitable for treating gases with high hydrogen sulfide content.

[0004] Ionic liquids are liquid compounds composed entirely of anions and cations at room temperature or above; they are liquid ionic compounds. Compared to traditional organic solvents, ionic liquids possess many superior properties, such as a wide liquid range, good solubility, low saturated vapor pressure, good thermal and chemical stability, and high conductivity, providing a better desulfurizing agent for hydrogen sulfide removal processes in industrial production. Iron-based ionic liquids not only possess the numerous advantages of ionic liquids themselves, with a thermal decomposition temperature greater than 200℃ and good stability, but also share characteristics with both Bronsted and Lewis acids, enabling the oxidation of hydrogen sulfide under acidic conditions without the formation of byproducts, thus avoiding the shortcomings of existing desulfurization processes. The active component, Fe... 3+ It can also be regenerated by circulating air, eliminating the need for auxiliary reagents and pH adjustment during the desulfurization process. Ionic liquids possess highly oxidizing Fe... 3+ This allows ionic liquids to not only absorb hydrogen sulfide but also react with it, resulting in a higher absorption rate of hydrogen sulfide. This has attracted the research interest of many scholars in recent years.

[0005] Chinese Patent No. CN102020610A, entitled "Low Viscosity Ionic Liquid," proposes an ionic liquid obtained by directly mixing and reacting a chlorinated alkylimidazolium compound with ferric chloride in an open environment. This ionic liquid exhibits not only low viscosity and strong hydrophobicity but also high thermal stability and oxidizing power. Chinese Patent No. CN102020248B, entitled "A Method for Wet Oxidation of Hydrogen Sulfide in a Non-Aqueous Phase," proposes that chlorinated alkylimidazolium-based iron-based ionic liquids are extremely hydrophobic liquids that can automatically separate from water during regeneration, avoiding dilution of the iron-based ionic liquid by water. Chinese Patent No. CN202110285037.3, entitled "A Method for Wet Oxidation of Hydrogen Sulfide and Removal of Carbon Dioxide Using Iron-Based Ionic Liquids," proposes a desulfurizing agent composed of a pyridine-based iron-based ionic liquid, achieving highly efficient absorption and separation of hydrogen sulfide from gases. Chinese Patent No. CN113019078A, entitled "A Morpholine-based Iron-based Ionic Liquid and Its Application in Removing Hydrogen Sulfide from Gas," proposes a desulfurizing agent composed of a morpholine-based iron-based ionic liquid that achieves efficient absorption and separation of hydrogen sulfide from gas.

[0006] Because iron-based ionic liquids are acidic, H2S is first physically absorbed in them and then oxidized to form elemental sulfur. Therefore, increasing the solubility of H2S in iron-based ionic liquids helps improve their oxidative desulfurization capabilities. Research has shown that a larger molar volume provides more free space for the ionic liquid, allowing it to accommodate more H2S molecules and thus increasing H2S solubility. Therefore, this patent proposes a method for preparing the iron-containing coordination ionic liquid Fe((OHCH2CH2)2NH)6(CF3SO3)3 and its application in gas desulfurization. Summary of the Invention

[0007] One objective of this invention is to provide a method for catalytically oxidizing and removing hydrogen sulfide using an iron-containing coordination ionic liquid as a liquid-phase absorption system. This method involves thoroughly mixing and reacting a solid metal salt, Fe(CF3SO3)3, with a liquid, NH(CH2CH2OH)2 in an inert gas environment to form a liquid-liquid or liquid-solid multiphase system. The iron-based ionic liquid phase can then be directly separated to obtain the iron-containing coordination ionic liquid absorbent. This type of iron-based ionic liquid has a large molar volume, resulting in a high H2S solubility, overcoming the low H2S solubility of existing iron-based ionic liquids. Furthermore, after the desulfurization reaction, the desulfurization products are easily separated from the desulfurizing agent system. The operation process is simple, and the reacted iron-based ionic liquid can be regenerated and recycled.

[0008] The iron-containing coordination ionic liquid of the present invention has a viscosity of 30-130 mPa·s at 20°C and a water content of no more than 100 ppm.

[0009] A second objective of this invention is to provide a method for preparing the aforementioned iron-containing coordination ionic liquid. The steps of the synthesis and preparation process of the iron-containing coordination ionic liquid are as follows:

[0010] (1) The preparation method of the iron-containing coordination ionic liquid Fe((OHCH2CH2)2NH)6(CF3SO3)3 is as follows: liquid NH(CH2CH2OH)2 is used as raw material and is directly mixed with solid metal salt Fe(CF3SO3)3 in a reaction apparatus. The molar ratio of liquid NH(CH2CH2OH)2 to solid metal salt Fe(CF3SO3)3 is 6:1. The reaction is carried out continuously for 30-40 h under constant temperature of 70-85℃ and uniform stirring. The product obtained after the reaction is washed 2-5 times with hot ethyl acetate and then vacuum evaporated for 10 h in a rotary evaporator under constant temperature of 60-80℃ to obtain the iron-containing coordination ionic liquid Fe((OHCH2CH2)2NH)6(CF3SO3)3.

[0011] (2) The purity of the liquid NH(CH2CH2OH)2 and the solid metal salt Fe(CF3SO3)3 is above 99%.

[0012] A third objective of this invention is to provide a method for removing hydrogen sulfide gas using an iron-containing coordination ionic liquid, comprising the following steps:

[0013] (1) Prepare the iron-containing coordination ionic liquid Fe((OHCH2CH2)2NH)6(CF3SO3)3 by thoroughly mixing and stirring liquid NH(CH2CH2OH)2 with solid metal salt Fe(CF3SO3)3;

[0014] (2) The water content in the iron-containing coordination ionic liquid Fe((OHCH2CH2)2NH)6(CF3SO3)3 was reduced to less than 100 ppm by vacuum drying.

[0015] (3) Hydrogen sulfide gas is introduced into the iron-containing coordination ionic liquid Fe((OHCH2CH2)2NH)6(CF3SO3)3 to undergo a catalytic oxidation reaction, thereby absorbing and removing hydrogen sulfide.

[0016] (4) The iron-containing coordination ionic liquid Fe((OHCH2CH2)2NH)6(CF3SO3)3 after the desulfurization reaction is completed is regenerated and recycled.

[0017] Preferably, the preparation method of the iron-containing coordination ionic liquid Fe((OHCH2CH2)2NH)6(CF3SO3)3 is as follows: liquid NH(CH2CH2OH)2 is used as raw material and directly mixed with solid metal salt Fe(CF3SO3)3 in a reaction apparatus, with a molar ratio of liquid NH(CH2CH2OH)2 to solid metal salt Fe(CF3SO3)3 of 6:1; the reaction is carried out continuously for 30-40 h under constant temperature in a water bath at 70-85℃ and uniform stirring; the product obtained after the reaction is washed 2-5 times with hot ethyl acetate, and then vacuum evaporated for 10 h in a rotary evaporator under constant temperature in a water bath at 60-80℃ to obtain the iron-containing coordination ionic liquid Fe((OHCH2CH2)2NH)6(CF3SO3)3.

[0018] Preferably, the purity of the raw material liquid NH(CH2CH2OH)2 and the solid metal salt Fe(CF3SO3)3 used to prepare the iron-containing coordination ionic liquid Fe((OHCH2CH2)2NH)6(CF3SO3)3 is above 99%.

[0019] Preferably, the viscosity of the iron-containing coordination ionic liquid Fe((OHCH2CH2)2NH)6(CF3SO3)3 at 20℃ is 30-130 mPa·s.

[0020] Preferably, the iron-containing coordination ionic liquid Fe((OHCH2CH2)2NH)6(CF3SO3)3 acts as both a catalyst and an oxidant, wherein the Fe... 3+ The ions act as oxidizing agents to convert hydrogen sulfide into elemental sulfur.

[0021] Preferably, the elemental sulfur is insoluble in the desulfurizing agent system, and the sulfur particles are separated by centrifugation, sedimentation and filtration, so that the iron-containing coordination ionic liquid Fe((OHCH2CH2)2NH)6(CF3SO3)3 can be regenerated and recycled.

[0022] Preferably, air or oxygen is introduced into the iron-containing coordination ionic liquid Fe((OHCH2CH2)2NH)6(CF3SO3)3 after the desulfurization reaction, while the pressure is reduced and the liquid is heated, so that the iron-containing coordination ionic liquid Fe((OHCH2CH2)2NH)6(CF3SO3)3 after the desulfurization reaction is regenerated and recycled.

[0023] This invention constructs a desulfurization system using an iron-containing coordination ionic liquid as the absorbent. Compared with other iron-based ionic liquids, it not only has the advantages of being green, environmentally friendly, and recyclable, but also has a large molar volume and greater solubility than existing iron-based ionic liquids. The desulfurization products are easily separated from the desulfurizing agent system, the operation process is simple, and it is easy to realize industrial desulfurization. Detailed Implementation

[0024] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the embodiments of this application. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0025] One of the objectives of this invention is to provide a method for catalytically oxidizing and removing hydrogen sulfide using an iron-containing coordination ionic liquid as a liquid-phase absorption system. The method involves fully mixing and reacting a solid metal salt Fe(CF3SO3)3 with a liquid NH(CH2CH2OH)2 in an inert gas environment to form a liquid-liquid or liquid-solid multiphase system. The iron-based ionic liquid phase can be directly separated to obtain the iron-containing coordination ionic liquid absorbent.

[0026] This type of iron-based ionic liquid has a large molar volume, which gives it a high H2S solubility, overcoming the disadvantage of low H2S solubility in existing iron-based ionic liquids. Furthermore, after the iron-based ionic liquid desulfurization reaction of the absorbent, the desulfurization products are easily separated from the desulfurizing agent system, the operation process is simple, and the iron-based ionic liquid after the reaction can be regenerated and recycled.

[0027] Preferably, the viscosity of the iron-containing coordination ionic liquid at 20°C is 30–130 mPa·s, and the water content of the product does not exceed 100 ppm.

[0028] A second objective of this invention is to provide a method for preparing the aforementioned iron-containing coordination ionic liquid. The steps of the synthesis and preparation process of the iron-containing coordination ionic liquid are as follows:

[0029] (1) Prepare the iron-containing coordination ionic liquid Fe((OHCH2CH2)2NH)6(CF3SO3)3 by thoroughly mixing and stirring liquid NH(CH2CH2OH)2 with solid metal salt Fe(CF3SO3)3;

[0030] (2) The water content in the iron-containing coordination ionic liquid Fe((OHCH2CH2)2NH)6(CF3SO3)3 was reduced to less than 100 ppm by vacuum drying.

[0031] (3) Hydrogen sulfide gas is introduced into the iron-containing coordination ionic liquid Fe((OHCH2CH2)2NH)6(CF3SO3)3 to undergo a catalytic oxidation reaction, thereby absorbing and removing hydrogen sulfide.

[0032] (4) The iron-containing coordination ionic liquid Fe((OHCH2CH2)2NH)6(CF3SO3)3 after the desulfurization reaction is completed is regenerated and recycled.

[0033] The third objective of this invention is to provide a method for removing hydrogen sulfide from gas using the iron-containing coordination ionic liquid. The iron-containing coordination ionic liquid is used as an absorbent, and gas containing a certain concentration of hydrogen sulfide is passed into the iron-containing coordination ionic liquid absorbent to undergo a catalytic oxidation reaction and remove the hydrogen sulfide.

[0034] One method for removing hydrogen sulfide gas using iron-containing coordination ionic liquids includes the following steps:

[0035] (1) Prepare the iron-containing coordination ionic liquid Fe((OHCH2CH2)2NH)6(CF3SO3)3 by thoroughly mixing and stirring liquid NH(CH2CH2OH)2 with solid metal salt Fe(CF3SO3)3;

[0036] (2) The water content in the iron-containing coordination ionic liquid Fe((OHCH2CH2)2NH)6(CF3SO3)3 was reduced to less than 100 ppm by vacuum drying.

[0037] (3) Hydrogen sulfide gas is introduced into the iron-containing coordination ionic liquid Fe((OHCH2CH2)2NH)6(CF3SO3)3 to undergo a catalytic oxidation reaction, thereby absorbing and removing hydrogen sulfide.

[0038] (4) The iron-containing coordination ionic liquid Fe((OHCH2CH2)2NH)6(CF3SO3)3 after the desulfurization reaction is completed is regenerated and recycled.

[0039] Preferably, in the desulfurization process of the iron-containing coordination ionic liquid, the concentration of H2S in the gas is 0.1%-1%, the loading rate is 0.1-0.3 mL / min of gas per mL of ionic liquid, the temperature is 20-80℃, and the product is elemental sulfur, which exists in the form of sulfur particles at the bottom of the absorbent and can be separated by centrifugation, sedimentation and filtration.

[0040] Preferably, air or oxygen is introduced into the absorbent after the hydrogen sulfide gas has been absorbed, so that the iron-based ionic liquid can be regenerated, thereby realizing the recycling of iron-containing coordination ionic liquid.

[0041] The steps for removing hydrogen sulfide from iron-containing coordination ionic liquids are as follows:

[0042] Add 100-200 mL of iron-containing coordination ionic liquid to the reactor, controlling the reaction temperature at 20-80℃. Introduce 0.1%-1% hydrogen sulfide standard gas at a constant pressure and a gas velocity of 10-30 mL / min (0.1-0.3 mL / min per mL of ionic liquid) from the bottom of the reactor. After introduction, the gas passes through the iron-containing coordination ionic liquid desulfurization system as small bubbles from the bottom of the reactor. Extract the tail gas every 5 minutes and test for hydrogen sulfide. When the hydrogen sulfide concentration in the extracted tail gas is detected to be greater than 10 ppm, record the reaction time and calculate the corresponding sulfur capacity. The sulfur capacity calculation formula is:

[0043]

[0044] In the above formula, S is the sulfur capacity (g / L), Q is the gas flow rate (mL / min), and V is the ionic liquid volume (mL).

[0045] The ionic liquid that has absorbed hydrogen sulfide is centrifuged at 1000-5000 r / min for 5-20 min. The resulting sulfur precipitate is filtered, washed 4-5 times with deionized water, and then vacuum dried at 60-85℃ for 2-5 h, finally yielding pale yellow sulfur particles. The ionic liquid that has absorbed hydrogen sulfide is then subjected to infrared spectroscopy analysis to determine whether byproducts such as sulfates, thiosulfates, and sulfites are formed.

[0046] A fourth objective of this invention is to provide a method for regenerating the iron-based ionic liquid, wherein the regeneration process of the iron-containing coordination ionic liquid involves a loading rate of 0.02-0.2 mL / min for air or oxygen per mL of ionic liquid, a temperature of 35-55°C, and when Fe in the ionic liquid... 2+ Regeneration is completed when the concentration is zero.

[0047] The steps for regenerating iron-containing coordination ionic liquid desulfurizers are as follows:

[0048] Under normal pressure, air or pure oxygen is introduced into the iron-based ionic liquid absorbent after sulfur recovery in a bottom-in, top-out manner. The regeneration temperature is controlled at 35-55℃, and the air flow rate is 10-25 mL / min (the flow rate of air or oxygen introduced per mL of ionic liquid is 0.02-0.2 mL / min). Every 5-30 minutes, 0.5 mL of the absorbent during regeneration is measured to determine the Fe content. 2+ Concentration, when Fe is not detected in the absorbent three times consecutively. 2+ The regeneration of the absorbent is considered complete when it is present.

[0049] This invention constructs a desulfurization system using an iron-containing coordination ionic liquid as the absorbent. Compared with other iron-based ionic liquids, it not only has the advantages of being green, environmentally friendly, and recyclable, but also has a large molar volume and greater solubility than existing iron-based ionic liquids. The desulfurization products are easily separated from the desulfurizing agent system, the operation process is simple, and it is easy to realize industrial desulfurization.

[0050] The following details the specific implementation methods for removing hydrogen sulfide gas using iron-containing coordination ionic liquids.

[0051] Example 1

[0052] 2.00 g of recrystallized Fe(CF3SO3)3 sample and 2.51 g of NH(CH2CH2OH)2 liquid were sequentially added to a 20 mL glass bottle and mixed thoroughly for several minutes. The mixture was then heated in an oven to 115 °C for 15-20 minutes. The mixture was then sonicated for 5 minutes, and the solution was heated again to 115 °C for 15-20 minutes to produce the iron-coordinated ionic liquid Fe((OHCH2CH2)2NH)6(CF3SO3)3, with a yield of 99.9%.

[0053] 3 g of the synthesized Fe((OHCH2CH2)2NH)6(CF3SO3)3 was weighed into a 50 mL beaker and stirred at a constant speed in a N2 environment for 36 h to obtain a dark reddish-brown iron-containing coordination ionic liquid. The synthesized ionic liquid was placed in a vacuum drying oven and dried under vacuum (pressure 2.5 kPaA) at 60 °C for 48 h. The water content was determined to be less than 100 ppm using a Karl Fischer titrator. The viscosity was measured to be 56 mPa·s using a viscometer at 20 °C.

[0054] 150 mL of the synthesized iron-containing coordination ionic liquid was injected into the reactor, and the absorption temperature was kept constant at 40 °C. A 1% hydrogen sulfide standard gas was introduced at a flow rate of 22.5 mL / min (0.15 mL / min of gas per mL of ionic liquid). The tail gas was sampled every 5 min and tested for hydrogen sulfide. The reaction was stopped when the hydrogen sulfide concentration in the tail gas exceeded 10 ppm after 573 min. Under these conditions, the sulfur capacity was 5.85 g / L.

[0055] Infrared spectroscopy analysis of the ionic liquid that had absorbed hydrogen sulfide revealed the absence of a 3300 cm⁻¹ depth. -1 The -OH contraction vibration peak at the location indicates that no byproducts such as sulfate, thiosulfate, and sulfite are generated during the absorption reaction.

[0056] The ionic liquid that has absorbed hydrogen sulfide was centrifuged at 5000 r / min for 20 min. The resulting sulfur precipitate was washed 4-5 times with deionized water and then vacuum dried at 85℃ for 3 h to obtain 0.8320 g of pale yellow sulfur.

[0057] The ionic liquid that had absorbed hydrogen sulfide was placed in a regeneration reactor. The reaction temperature was set to 40℃, and pure oxygen was introduced into the reactor at a flow rate of 15 mL / min under normal pressure (the oxygen flow rate per mL of ionic liquid was 0.1 mL / min). Every 5-30 minutes, 0.5 mL of the ionic liquid was taken from the reactor to detect the Fe content. 2+ The content of Fe was undetectable in three consecutive samples. 2+ The presence of Fe indicates that oxidation and regeneration are complete. After 135 minutes of reaction, Fe was undetectable in the ionic liquid sample three times consecutively. 2+ The existence of.

[0058] Example 2

[0059] 2.10 g of recrystallized Fe(CF3SO3)3 sample and 2.61 g of NH(CH2CH2OH)2 liquid were sequentially added to a 20 mL glass bottle and mixed thoroughly for several minutes. The mixture was then heated in an oven to 130 °C for 15-20 minutes. The mixture was then sonicated for 5 minutes, and the solution was heated again to 130 °C for 15-20 minutes to produce the iron-coordinated ionic liquid Fe((OHCH2CH2)2NH)6(CF3SO3)3, with a yield of 90.7%.

[0060] 3.5 g of the synthesized Fe((OHCH2CH2)2NH)6(CF3SO3)3 was weighed into a 50 mL beaker and stirred at a constant speed in a N2 environment for 45 h to obtain a dark reddish-brown iron-containing coordination ionic liquid. The synthesized ionic liquid was placed in a vacuum drying oven and dried under vacuum (pressure 2.5 kPaA) at 70 °C for 72 h. The water content was determined to be less than 100 ppm using a Karl Fischer titrator. The viscosity was measured to be 40 mPa·s using a viscometer at 20 °C.

[0061] 150 mL of the synthesized iron-containing coordination ionic liquid was injected into the reactor, and the absorption temperature was kept constant at 50 °C. A 0.5% hydrogen sulfide standard gas was introduced at a flow rate of 45 mL / min (0.3 mL / min of gas per mL of ionic liquid). The tail gas was sampled every 5 min and tested for hydrogen sulfide. The reaction was stopped when the hydrogen sulfide concentration in the tail gas exceeded 10 ppm after 602 min. Under these conditions, the sulfur capacity was 5.12 g / L.

[0062] Infrared spectroscopy analysis of the ionic liquid that had absorbed hydrogen sulfide revealed the absence of a 3300 cm⁻¹ depth.-1 The -OH contraction vibration peak at the location indicates that no byproducts such as sulfate, thiosulfate, and sulfite are generated during the absorption reaction.

[0063] The ionic liquid that has absorbed hydrogen sulfide was centrifuged at 3000 r / min for 10 min. The resulting sulfur precipitate was washed 4-5 times with deionized water and then vacuum dried at 60℃ for 5 h to obtain 1.0144 g of pale yellow sulfur.

[0064] The ionic liquid that had absorbed hydrogen sulfide was placed in a regeneration reactor. The reaction temperature was set to 50°C, and pure oxygen was introduced into the reactor at a flow rate of 25 mL / min under normal pressure (the oxygen flow rate per mL of ionic liquid was 0.17 mL / min). Every 5-30 minutes, 0.5 mL of the ionic liquid was taken from the reactor to detect the Fe content. 2+ The content of Fe was undetectable in three consecutive samples. 2+ The presence of Fe indicates that oxidation and regeneration are complete. After 254 minutes of reaction, Fe was undetectable in the ionic liquid sample three times consecutively. 2+ The existence of.

[0065] Example 3

[0066] 2.50 g of recrystallized Fe(CF3SO3)3 sample and 2.81 g of NH(CH2CH2OH)2 liquid were sequentially added to a 20 mL glass bottle and mixed thoroughly for several minutes. The mixture was then heated in an oven to 150 °C for 15-20 minutes. The mixture was then sonicated for 5 minutes, and the solution was heated again to 150 °C for 15-20 minutes to produce the iron-coordinated ionic liquid Fe((OHCH2CH2)2NH)6(CF3SO3)3, with a yield of 85.7%.

[0067] 3.7 g of the synthesized Fe((OHCH2CH2)2NH)6(CF3SO3)3 was weighed into a 50 mL beaker and stirred at a constant speed in a N2 environment for 40 h to obtain a dark reddish-brown iron-containing coordination ionic liquid. The synthesized ionic liquid was placed in a vacuum drying oven and dried under vacuum (pressure 2.5 kPaA) at 80 °C for 96 h. The water content was determined to be less than 100 ppm using a Karl Fischer titrator. The viscosity was measured to be 121 mPa·s using a viscometer at 20 °C.

[0068] 150 mL of the synthesized iron-containing coordination ionic liquid was injected into the reactor, and the absorption temperature was kept constant at 55 °C. A 1% hydrogen sulfide standard gas was introduced at a flow rate of 22.5 mL / min (0.15 mL / min of gas per mL of ionic liquid). The tail gas was sampled every 5 min and tested for hydrogen sulfide. The reaction was stopped when the hydrogen sulfide concentration in the tail gas exceeded 10 ppm after 467 min. Under these conditions, the sulfur capacity was 4.90 g / L.

[0069] Infrared spectroscopy analysis of the ionic liquid that had absorbed hydrogen sulfide revealed the absence of a 3300 cm⁻¹ depth. -1 The -OH contraction vibration peak at the location indicates that no byproducts such as sulfate, thiosulfate, and sulfite are generated during the absorption reaction.

[0070] The ionic liquid that has absorbed hydrogen sulfide was centrifuged at 5000 r / min for 20 min. The resulting sulfur precipitate was washed 4-5 times with deionized water and then vacuum dried at 85℃ for 3 h to obtain 0.8233 g of pale yellow sulfur.

[0071] The ionic liquid that had absorbed hydrogen sulfide was placed in a regeneration reactor. The reaction temperature was set to 45℃, and pure oxygen was introduced into the reactor at a flow rate of 15 mL / min under normal pressure (the oxygen flow rate per mL of ionic liquid was 0.1 mL / min). Every 5-30 minutes, 0.5 mL of the ionic liquid was taken from the reactor to detect the Fe content. 2+ The content of Fe was undetectable in three consecutive samples. 2+ The presence of Fe indicates that oxidation and regeneration are complete. After 147 minutes of reaction, Fe was not detected in the ionic liquid sample three times consecutively. 2+ The existence of.

[0072] Example 4

[0073] 2.80 g of recrystallized Fe(CF3SO3)3 sample and 3.11 g of NH(CH2CH2OH)2 liquid were sequentially added to a 20 mL glass bottle and mixed thoroughly for several minutes. The mixture was then heated in an oven to 180 °C for 15-20 minutes. The mixture was then sonicated for 5 minutes, and the solution was heated again to 180 °C for 15-20 minutes to produce the iron-coordinated ionic liquid Fe((OHCH2CH2)2NH)6(CF3SO3)3, with a yield of 82.7%.

[0074] 3.9 g of the synthesized Fe((OHCH2CH2)2NH)6(CF3SO3)3 was weighed into a 50 mL beaker and stirred at a constant speed in a N2 environment for 50 h to obtain a dark reddish-brown iron-containing coordination ionic liquid. The synthesized ionic liquid was placed in a vacuum drying oven and dried under vacuum (pressure 2.5 kPaA) at 80 °C for 120 h. The water content was determined to be less than 100 ppm using a Karl Fischer titrator. The viscosity was measured to be 117 mPa·s using a viscometer at 20 °C.

[0075] 150 mL of the synthesized iron-containing coordination ionic liquid was injected into the reactor, and the absorption temperature was kept constant at 60 °C. A 0.5% hydrogen sulfide standard gas was introduced at a flow rate of 45 mL / min (0.3 mL / min of gas per mL of ionic liquid). The tail gas was sampled every 5 min and tested for hydrogen sulfide. The reaction was stopped when the hydrogen sulfide concentration in the tail gas exceeded 10 ppm after 516 min. Under these conditions, the sulfur capacity was 4.55 g / L.

[0076] Infrared spectroscopy analysis of the ionic liquid that had absorbed hydrogen sulfide revealed the absence of a 3300 cm⁻¹ depth. -1 The -OH contraction vibration peak at the location indicates that no byproducts such as sulfate, thiosulfate, and sulfite are generated during the absorption reaction.

[0077] The ionic liquid that has absorbed hydrogen sulfide was centrifuged at 5000 r / min for 20 min. The resulting sulfur precipitate was washed 4-5 times with deionized water and then vacuum dried at 60℃ for 5 h to obtain 0.7525 g of pale yellow sulfur.

[0078] The ionic liquid that had absorbed hydrogen sulfide was placed in a regeneration reactor. The reaction temperature was set to 55℃, and pure oxygen was introduced into the reactor at a flow rate of 25 mL / min (0.2 mL / min of oxygen per mL of ionic liquid) under normal pressure. Every 5-30 minutes, 0.5 mL of the ionic liquid was taken from the reactor to detect the Fe content. 2+ The content of Fe was undetectable in three consecutive samples. 2+ The presence of Fe indicates that oxidation and regeneration are complete. After 76 minutes of reaction, Fe was undetectable in the ionic liquid sample three times consecutively. 2+ The existence of.

[0079] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0080] The embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the technical solutions and core ideas of this application. Those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A method for removing hydrogen sulfide gas using an iron-containing coordination ionic liquid, characterized in that, Including the following steps: (1) Prepare the ionic liquid Fe((OHCH2CH2)2NH)6(CF3SO3)3 by mixing and stirring solid metal salt Fe(CF3SO3)3 and liquid NH(CH2CH2OH)2 at a molar ratio of 1:6; (2) The reaction is carried out continuously at a constant temperature of 70-85℃ in a water bath for 30-40 h with uniform stirring, or at a high temperature of 115-180℃ for 15-20 min. The product obtained after the reaction is washed 2-5 times with hot ethyl acetate. (3) Vacuum evaporation was performed in a rotary evaporator at a constant temperature water bath of 60~80℃ for 10 h. The water content in the iron-containing coordination ionic liquid Fe((OHCH2CH2)2NH)6(CF3SO3)3 was reduced to less than 100 ppm by vacuum drying. (4) Hydrogen sulfide gas is introduced into the iron-containing coordination ionic liquid Fe((OHCH2CH2)2NH)6(CF3SO3)3 to undergo a catalytic oxidation reaction, thereby absorbing and removing hydrogen sulfide. (5) The iron-containing coordination ionic liquid Fe((OHCH2CH2)2NH)6(CF3SO3)3 after the desulfurization reaction is completed is regenerated and recycled.

2. The method according to claim 1, characterized in that, The preparation process of the iron-containing coordination ionic liquid Fe((OHCH2CH2)2NH)6(CF3SO3)3 involves fully mixing and reacting the solid metal salt Fe(CF3SO3)3 with the liquid NH(CH2CH2OH)2 in an inert gas environment to form a liquid-liquid or liquid-solid multiphase system, which can then be obtained by directly separating the iron-based ionic liquid phase.

3. The method according to claim 1, characterized in that, The viscosity of the iron-containing coordination ionic liquid Fe((OHCH2CH2)2NH)6(CF3SO3)3 at 20℃ is 30~130 mPa·s.

4. The method according to claim 1, characterized in that, The iron-containing coordination ionic liquid Fe((OHCH2CH2)2NH)6(CF3SO3)3 acts as both a catalyst and an oxidant, in which Fe 3+ The ions act as oxidizing agents to convert hydrogen sulfide into elemental sulfur.

5. The method according to claim 4, characterized in that, The elemental sulfur is insoluble in the desulfurizing agent system. The sulfur particles are separated by centrifugation, sedimentation and filtration, so that the iron-containing coordination ionic liquid Fe((OHCH2CH2)2NH)6(CF3SO3)3 can be regenerated and recycled.

6. The method according to claim 1, characterized in that, Air or oxygen is introduced into the iron-containing coordination ionic liquid Fe((OHCH2CH2)2NH)6(CF3SO3)3 after the desulfurization reaction, while the pressure is reduced and the liquid is heated, so that the iron-containing coordination ionic liquid Fe((OHCH2CH2)2NH)6(CF3SO3)3 after the desulfurization reaction is regenerated and recycled.

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