Iron-based ionic liquid oxidation desulfurization method

Abstract

The application discloses a kind of iron-based ionic liquid oxidation desulfurization method, hydrogen sulfide gas is introduced into desulfurizer and is desulfurized.Therein, the desulfurizer used includes iron-based ionic liquid, cosolvent and acid control agent, acid control agent is preferably alcohol amine, the use of alcohol amine not only greatly improves the sulfur capacity of desulfurizer, can reach 41.14g / L, simultaneously with H + There is stronger binding capacity, resulting in the initial reaction of homogeneous desulfurizer phase separation, the alcohol amine phase formed by phase separation forms liquid seal relative to iron-based ionic liquid phase, binds the escape of acidic gas in desulfurization liquid, avoids the destruction of desulfurizer structure, the corrosion of equipment caused by strong acidic system and the environmental pollution caused by acidic gas escape, realizes 100% desulfurization.In addition, the desulfurizer described in the application has high thermal stability and chemical stability.

Description

Technical Field

[0001] This invention belongs to the field of metal-based ionic liquid oxidation desulfurization, specifically relating to a method for the oxidation and absorption of sulfuric acid-containing gases. Background Technology

[0002] Hydrogen sulfide is a highly toxic and harmful gas that not only pollutes the environment and endangers human health, but also corrodes equipment in industrial processes and deactivates catalysts. Therefore, the removal of hydrogen sulfide is of great significance.

[0003] Currently, the main methods for industrial hydrogen sulfide removal include Claus tail gas hydrodesulfurization and Lo-Cat wet aqueous phase oxidation desulfurization. Claus tail gas hydrodesulfurization is limited by thermodynamic equilibrium, resulting in a total sulfur content of approximately 10,000 ppm in the desulfurized tail gas. It typically needs to be combined with an ultra-Claus process to meet emission standards. Lo-Cat wet aqueous phase oxidation desulfurization uses iron complexes such as EDTA-Fe aqueous solution as the desulfurizing agent. The solution pH needs to be controlled between 6 and 8, and the process involves issues of desulfurizing agent degradation and secondary pollution.

[0004] Since the 1980s, N-methyldiethanolamine (MDEA) has seen rapid development and application due to its outstanding energy-saving advantages. After more than 30 years of development, various solution systems based on MDEA as the main agent have been formed. MDEA formulation solutions use MDEA as the main agent, supplemented with certain additives to improve some properties of the MDEA solution. It can simultaneously absorb H2S and CO2, and is typically used in industrial desulfurization and decarbonization with a 40-45% MDEA aqueous solution. Related patents include CN109810740A, CN107433108A, CN205710634U, and CN105664698A. The Southwest Oil and Gas Field Natural Gas Research Institute of PetroChina has developed the CT8-5 type desulfurizer based on MDEA for the removal of hydrogen sulfide, which can effectively prevent foaming. However, components such as NH3 and CO2 in the feed gas easily generate thermally stable salts in the MDEA system, increasing desulfurizer consumption, reducing desulfurization efficiency, and causing equipment corrosion. Because MDEA has a high viscosity, it usually needs to be mixed with water before use. Therefore, the operating temperature of MDEA desulfurizer is generally no more than 60℃.

[0005] Ionic liquids, as environmentally friendly green solvents, possess a wide liquid range, high thermal and chemical stability, low vapor pressure, non-volatility, strong solubility, tunable structure, easy recovery, good conductivity, and a wide electrochemical window compared to traditional organic solvents. They have broad applications in organic synthesis, catalysis, separation, and electrochemistry. Metal-based ionic liquids combine the catalytic function of metal ions with the characteristics of ionic liquids, possessing both catalytic and gas absorption centers. However, metal-based ionic liquids are highly acidic; during desulfurization, a large amount of HCl accumulated escapes, causing equipment corrosion, damaging the desulfurization liquid structure, and reducing the H+ content in the rich desulfurization liquid. + The concentration of sulfur dioxide decreases, thereby reducing the efficiency of subsequent desulfurization. Summary of the Invention

[0006] To overcome the aforementioned problems, the inventors conducted intensive research and developed an iron-based ionic liquid oxidative desulfurization method, in which hydrogen sulfide gas is passed into a desulfurizing agent for desulfurization. The desulfurizing agent used includes an iron-based ionic liquid, a co-solvent, and an acid control agent. The co-solvent acts as both an antifoaming agent and a physical solvent, leveraging its excellent absorption effect on hydrogen sulfide to promote the physical dissolution of the hydrogen sulfide gas. The preferred acid control agent is an alkanolamine. The use of alkanolamine not only significantly increases the sulfur capacity of the desulfurizing agent, reaching 41.14 g / L, but also reacts with the H₂ produced during the desulfurization process. + It has a stronger binding capacity, causing the initially homogeneous desulfurizer to separate into two phases. The alkanolamine phase formed during this phase separation forms a liquid seal against the iron-based ionic liquid phase, restricting the escape of acidic gases from the desulfurization liquid. This avoids damage to the desulfurizer structure, equipment corrosion caused by the strongly acidic system, and environmental pollution caused by the escape of acidic gases, achieving 100% desulfurization. Furthermore, the desulfurizer described in this invention exhibits high thermal and chemical stability, thus completing this invention.

[0007] Specifically, the object of the present invention is to provide the following aspects:

[0008] In one aspect, a desulfurizing agent is provided, which can achieve 100% desulfurization after being regenerated and recycled more than 6 times, and its sulfur capacity can reach more than 40g / L.

[0009] Secondly, a method for iron-based ionic liquid oxidation desulfurization is provided. The method involves performing iron-based ionic liquid oxidation desulfurization in a desulfurization device, which includes a desulfurization tower and a regeneration tower, with a sulfur settling tank connected between the desulfurization tower and the regeneration tower via a pipeline. The method includes: placing a desulfurizing agent in the desulfurization tower, introducing H2S gas into the desulfurization tower, and starting the desulfurization device for desulfurization.

[0010] The beneficial effects of this invention include:

[0011] (1) The desulfurizer provided by the present invention can achieve 100% desulfurization efficiency and its sulfur capacity is greatly improved. It is a non-aqueous phase desulfurizer. Compared with traditional aqueous phase desulfurizers, it has the advantages of high thermal stability and chemical stability, low vapor pressure, good solubility, no desulfurizer degradation and no secondary pollution.

[0012] (2) According to the desulfurizing agent provided by the present invention, the desulfurizing agent includes a cosolvent and an acid control agent. The cosolvent can effectively promote the physical dissolution of hydrogen sulfide gas and achieve efficient absorption of H2S. The acid control agent can avoid equipment corrosion caused by strong acid system.

[0013] (3) According to the iron-based ionic liquid oxidation desulfurization method provided by the present invention, during the desulfurization process, as H... + Increased concentration causes the initially homogeneous desulfurizer to separate into two phases. The alkanolamine phase formed by the phase separation forms a liquid seal against the iron-based ionic liquid phase, which restricts the escape of acidic gases from the desulfurization liquid. This solves the problem of acidic gas escape during the desulfurization process of iron-based ionic liquid, which causes structural damage to the desulfurizer and environmental pollution, and improves the desulfurization efficiency.

[0014] (4) According to the iron-based ionic liquid oxidation desulfurization method provided by the present invention, after the desulfurization is completed, the desulfurization rich liquid is regenerated by air / oxygen. During the regeneration process, the alcohol amine phase liquid film and the iron-based ionic liquid phase are miscible to form a homogeneous solution, and the addition of alcohol amine improves the air / oxygen regeneration efficiency, thereby achieving efficient cyclic phase change oxidation desulfurization. Attached Figure Description

[0015] Figure 1 A schematic diagram of a desulfurization device according to a preferred embodiment of the present invention is shown;

[0016] Figure 2 A comparison chart of the desulfurization efficiency of Example 1 is shown;

[0017] Figure 3 -(a) shows the desulfurization curve of Experiment Example 1;

[0018] Figure 3 -(b) shows a comparison of HCl content in the tail gas after desulfurization in Experiment Example 1;

[0019] Figure 4 The infrared spectrum of Experiment Example 2 is shown;

[0020] Figure 5 Thermogravimetric diagram of Experiment Example 3 is shown;

[0021] Figure 6 The XRD pattern of Experiment Example 4 is shown. Detailed Implementation

[0022] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Through these descriptions, the features and advantages of the present invention will become clearer and more apparent.

[0023] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments. Although various aspects of embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless specifically indicated otherwise.

[0024] A first aspect of the present invention is to provide a desulfurizing agent comprising an iron-based ionic liquid and a co-solvent.

[0025] According to the present invention, the iron-based ionic liquid has advantages such as good thermal stability, high sulfur quality, and no secondary pollution in removing hydrogen sulfide. When combined with a co-solvent, it can improve the sulfur capacity of the iron-based ionic liquid.

[0026] The iron-based ionic liquid includes organic amine-type iron-based ionic liquids such as triethylamine hydrochloride iron-based ionic liquid, or imidazole-based iron-based ionic liquids.

[0027] Furthermore, the iron-based ionic liquid is preferably an imidazole-based iron-based ionic liquid. Compared with organic amine-based iron-based ionic liquids, the imidazole-based iron-based ionic liquid is more resistant to high temperatures and belongs to non-aqueous phase catalytic oxidation for the removal of hydrogen sulfide. It can directly oxidize hydrogen sulfide to produce sulfur, avoiding the complex and cumbersome process operations such as continuous addition of desulfurizing agent and pH adjustment caused by the generation of by-product water in traditional wet desulfurization processes, which leads to a decrease in the concentration of desulfurizing agent and changes in the pH value of the system. It also avoids the problems of secondary pollution caused by the generation of a large amount of wastewater. Its essence is green desulfurization.

[0028] Furthermore, the iron-based ionic liquid is preferably an imidazole-based iron-based ionic liquid, such as 1-ethyl-3-methylimidazolium tetrachloride, 1-butyl-3-methylimidazolium tetrachloride, or 1-hexyl-3-methylimidazolium tetrachloride.

[0029] Furthermore, the iron-based ionic liquid is 1-butyl-3-methylimidazolium ferric chloride, which is prepared by stirring and reacting ferric chloride with a target ligand such as 1-butyl-3-methylchloroimidazolium.

[0030] In this invention, iron-based ionic liquid is used as a desulfurizing agent. Its high viscosity and strong acidity result in poor gas-liquid mass transfer rate and low working sulfur capacity. The sulfur capacity is comparable to that of traditional aqueous wet oxidation desulfurization, but much smaller than its theoretical sulfur capacity, which seriously hinders the ability of iron-based ionic liquid to efficiently absorb hydrogen sulfide.

[0031] The inventors constructed a composite desulfurizing agent by introducing a co-solvent as a physical solvent. Utilizing the excellent absorption effect of physical solvents on hydrogen sulfide, the agent first promotes the physical dissolution of hydrogen sulfide gas, and then leverages the high concentration of Fe in the iron-based ionic liquid. 3+ H2S is oxidized to form elemental sulfur, thereby preparing a high-sulfur-capacity desulfurizing agent to achieve efficient absorption and desulfurization of H2S.

[0032] According to the present invention, the selected co-solvent is an organic solvent with weak alkalinity and low viscosity, preferably a polyether polyol, such as phenolic polyether polyol, amine polyether polyol, sugar polyether polyol, sorbitol polyether polyol, alkyl polyether polyol, more preferably an alkyl polyether polyol, such as polyethylene glycol dimethyl ether, polyethylene glycol.

[0033] The inventors have discovered that using alkyl polyether polyols as co-solvents can not only form a well-miscible solvent system with iron-based ionic liquids, enhancing the desulfurization effect, but also has an anti-foaming effect. The desulfurization process does not generate a large amount of foam, thus avoiding flooding and eliminating the need to add defoamers during the reaction process, resulting in a mild desulfurization reaction.

[0034] According to the present invention, although the addition of a co-solvent achieves efficient absorption and desulfurization of H2S, the co-solvent is weakly alkaline with a pH close to 7, while the iron-based ionic liquid is strongly acidic, and the H2S generated during the desulfurization process... + This further increases the acidity of the system, causing corrosion to equipment in industrial processes.

[0035] To further address the above problems, the inventors added an acid control agent to the desulfurizing agent to reduce the acidity of the desulfurization system.

[0036] In this invention, the acid control agent is an organic base, including amine compounds or nitrogen-containing heterocyclic compounds, preferably amine compounds, more preferably alcoholic amines, such as N-methyldiethanolamine, diethanolamine, triethanolamine, ethanolamine, methylethanolamine, 2-amino-2-methyl-1-propanol, and diethylaminoethanol.

[0037] According to the present invention, the alkanolamine acts both as an acid control agent to adjust the pH of the system and as a physical solvent, further promoting the physical dissolution of hydrogen sulfide gas and achieving efficient absorption and desulfurization of H2S. More importantly, the H2S generated in the reaction... + It has a stronger binding ability with alcohol amines. As the reaction proceeds, the reaction system separates into phases. The alcohol amines formed by the phase separation form a liquid seal relative to the iron-based ionic liquid phase, successfully binding the escape of acidic gases such as hydrogen chloride from the desulfurization liquid.

[0038] Specifically, initially, the desulfurizing agent is homogeneous. As the desulfurization reaction proceeds, the H₂ in the desulfurization system... + As the concentration increases, due to H +It has a stronger binding ability with the alcohol amine phase; therefore, in the desulfurization reaction, the upper phase of the desulfurized rich liquor is enriched with H2. + The liquid film consists of an alcohol amine phase and an iron-based ionic liquid phase. The sulfur generated by the desulfurization reaction is a solid phase with high viscosity and density, distributed below the desulfurization rich liquid.

[0039] More specifically, since alkanolamines are alkaline and have a high capacity for absorbing acidic gases, and the combination products of alkanolamines and acidic gases have good stability, the alkanolamines formed during the desulfurization process form a liquid seal relative to the iron-based ionic liquid phase, which restricts the escape of acidic gases in the desulfurization liquid. This avoids damage to the desulfurizing agent structure and equipment corrosion and environmental pollution caused by the escape of acidic gases, and improves the desulfurization efficiency of the reaction.

[0040] In traditional industry, the amine method is widely used in industrial gas desulfurization, involving an exothermic acid-base neutralization reaction at relatively low temperatures, with the amine solution recycled via steam stripping. The N-methyldiethanolamine method, for example, is widely used in natural gas desulfurization because its hydrogen sulfide adsorption capacity exceeds that of physical absorbents at low temperatures. However, it suffers from drawbacks such as high cost, decreased economic viability with increasing hydrogen sulfide partial pressure in crude coal gas, and weak reactivity with organic sulfides, making it unsuitable for purifying gases with high organic sulfur content.

[0041] In this invention, an alkanolamine is used as a desulfurizing agent component. The interaction between the alkanolamine and the cosolvent avoids the damage to the structure of the acidic iron-based ionic liquid caused by using strong alkanolamine alone, and also reduces the acidity of the desulfurization system. This greatly improves the sulfur capacity of the desulfurizing agent desulfurization system and yields high-quality sulfur.

[0042] During the reaction, a gas-liquid-liquid emulsion phase is formed between the H2S gas and the desulfurizing agent. The H2S gas dissolves in the iron-based ionic liquid phase and is oxidized to elemental sulfur. + Transferred to the alcoholamine phase to form enriched H + The liquid film. Due to the enrichment of H2 formed during the desulfurization process. + The liquid film confines the escape of acidic gases from the desulfurization liquid, while the co-solvent promotes the physical dissolution of hydrogen sulfide gas, greatly improving the sulfur capacity of the desulfurization system. Therefore, the desulfurizer is not only suitable for purifying gases with low organic sulfur content, but also for purifying gases with high organic sulfur content. At the same time, it reduces the requirements for desulfurization reaction equipment. Even small-scale reaction equipment can still achieve 100% desulfurization efficiency using the desulfurizer described in this invention.

[0043] In this invention, the amount of acid control agent such as alkanolamine used is greatly reduced compared to the traditional industrial alkanolamine method. According to a preferred embodiment, the weight ratio of iron-based ionic liquid, co-solvent and acid control agent in the desulfurizing agent is (10-36):(1-16):(0.1-2), preferably (15-26):(3-13):(0.5-1.5), and more preferably (15-20):(5-9):(1.0-1.5).

[0044] In this invention, as the volume of the iron-based ionic liquid increases, the desulfurization capacity first increases and then decreases. When the volume ratio of the iron-based ionic liquid, the co-solvent, and the acid control agent is (10-36):(1-16):(0.1-2), especially (15-20):(5-9):(1.0-1.5), the desulfurizing agent system has a lower viscosity, stronger sulfur tolerance, and better desulfurization effect on H2S.

[0045] This involves avoiding the addition of excessive cosolvents and acid control agents to reduce Fe. 3+ The concentration of the solvent has a significant impact on desulfurization performance. When the weight ratio of iron-based ionic liquid, co-solvent, and acid control agent is within the above range, the desulfurization effect is particularly good.

[0046] In this invention, the sulfur capacity of the desulfurizing agent can reach 20 g / L or more, preferably 40 g / L or more; the desulfurization efficiency is 100% within a desulfurization time of 24 hours or less, and even within a desulfurization time of 48 hours or less; the desulfurizing agent can still achieve 100% desulfurization even after being regenerated and recycled more than 6 times, preferably, the desulfurizing agent is regenerated and recycled more than 12 times, for example, 20 times.

[0047] A second aspect of the present invention aims to provide a method for phase change oxidation desulfurization using the desulfurizing agent described in the first aspect. This method involves iron-based ionic liquid oxidation desulfurization in a desulfurization device, the desulfurization device comprising a desulfurization tower 1 and a regeneration tower 2, wherein a sulfur settling tank 12 is connected to the desulfurization tower 1 and the regeneration tower 2 via a pipeline. Figure 1 As shown.

[0048] The desulfurization reaction specifically includes: placing the desulfurizing agent in desulfurization tower 1, introducing H2S gas into desulfurization tower 1, and starting the desulfurization device to desulfurize.

[0049] In this invention, the desulfurizing agent is prepared by mixing an iron-based ionic liquid, a co-solvent, and an acid control agent.

[0050] In this invention, the iron-based ionic liquid includes organic amine-type iron-based ionic liquid or imidazole-based iron-based ionic liquid, preferably imidazole-based iron-based ionic liquid, more preferably chlorinated imidazole-based iron-based ionic liquid such as 1-ethyl-3-methylimidazolium tetrachloride, 1-butyl-3-methylimidazolium tetrachloride, 1-hexyl-3-methylimidazolium tetrachloride, and most preferably 1-butyl-3-methylimidazolium tetrachloride.

[0051] In this invention, the imidazole-based iron-based ionic liquid, taking 1-butyl-3-methylimidazolium tetrachloride as an example, is prepared by reacting ferric chloride with the target ligand 1-butyl-3-methylchloroimidazolium at room temperature under stirring. For example, it can be prepared by reacting anhydrous FeCl3 with 1-butyl-3-methylchloroimidazolium at room temperature under an inert atmosphere such as nitrogen for 12 hours, wherein the molar ratio of anhydrous FeCl3 to 1-butyl-3-methylchloroimidazolium is 1:1; or by reacting hydrated ferric chloride, such as FeCl3·6H2O, with 1-butyl-3-methylchloroimidazolium at room temperature under stirring for 24 hours, wherein the molar ratio of hydrated ferric chloride to 1-butyl-3-methylchloroimidazolium is 2:1.

[0052] In this invention, due to the desulfurization process, Fe 3+ It plays a major role in oxidative desulfurization, and excess Fe 3+ This makes the desulfurization effect of the desulfurizing agent more prominent.

[0053] According to the present invention, the co-solvent is an organic solvent with weak alkalinity and low viscosity, preferably a polyether polyol, such as phenolic polyether polyol, amine polyether polyol, sugar polyether polyol, sorbitol polyether polyol, alkyl polyether polyol, more preferably an alkyl polyether polyol, such as polyethylene glycol dimethyl ether, polyethylene glycol.

[0054] In this invention, the acid control agent is an organic base, including amine compounds and / or nitrogen-containing heterocyclic compounds, preferably amine compounds, and more preferably alcoholamines.

[0055] Further, the weight ratio of the iron-based ionic liquid, the co-solvent, and the acid control agent is (10–36):(1–16):(0.1–2), preferably (15–26):(3–13):(0.5–1.5), and more preferably (15–20):(5–9):(1.0–1.5).

[0056] In this invention, the desulfurizing agent is recyclable and possesses characteristics of both Bronsted acid and Lewis acid, wherein Fe... 3+ / Fe 2+ The ions exhibit excellent redox reversibility. They can directly oxidize H₂S for desulfurization under acidic conditions, with the active component being Fe. 3+Oxidation of H2S produces elemental sulfur and is converted into reduced Fe. 2+ Fe after regeneration 2+ Returning to the oxidized state of Fe 3+ The desulfurization process does not require the addition of auxiliary reagents or pH adjustment.

[0057] Furthermore, the volume concentration of H2S is between 0% and 100%.

[0058] In this invention, the desulfurization tower 1 includes a cavity at both the upper and lower ends through which gas or liquid can flow. The cavity contains a desulfurizing agent, and a temperature control device is provided on the outer wall of the cavity to provide a heat source for the cavity of the reactor 1.

[0059] During the reaction, the desulfurization temperature is controlled by a temperature control device installed on the outer wall of the desulfurization tower 1 chamber. The desulfurization temperature is 10-120℃, preferably 20-80℃, and more preferably 30-50℃.

[0060] According to the present invention, temperature changes have a significant impact on the desulfurization efficiency of the desulfurizing agent. Lower temperatures result in lower desulfurization efficiency; as the temperature increases, the desulfurization reaction rate increases, leading to better mass transfer of the gas in the ionic liquid, and significantly improving the desulfurization capacity of the iron-based ionic liquid in the desulfurizing agent. When the reaction temperature is between 10 and 120°C, the desulfurization efficiency is 100%.

[0061] In this invention, the bottom of the desulfurization tower 1 is connected to a gas conveying device, so that the gas containing H2S passes through the desulfurizing agent from bottom to top, increasing the desulfurization reaction time. The gas conveying device includes a gas supply device 7 and a gas flow meter 8. The gas flow meter 8 monitors the gas flow in real time, making the desulfurization reaction controllable.

[0062] In this invention, the flow rate of H2S gas introduced is controlled by a gas delivery device to be 10-100 mL / min, preferably 16-60 mL / min, and more preferably 20-50 mL / min.

[0063] According to the present invention, increasing the gas flow rate will reduce the residence time of H2S in the desulfurizing agent, resulting in insufficient contact between H2S molecules and ionic liquid, which in turn leads to a poorer desulfurization effect. When the H2S gas flow rate is 10-100 mL / min, the desulfurization efficiency reaches more than 99%.

[0064] In order to increase the reaction interface, a glass frit 6 is preferably provided at the bottom of the desulfurization tower 1. The gas containing H2S enters the desulfurization tower 1 from the bottom through the gas supply device 7. When passing through the glass frit 6, it is broken into small bubbles, thereby improving the desulfurization efficiency.

[0065] According to the present invention, a sampling port 9 is provided at the top of the desulfurization tower 1, which is connected to the tail gas absorption device 10 through a pipeline. The sampling port 9 is used to sample and monitor whether acidic gas is released during the desulfurization process.

[0066] The desulfurization tower 1 is equipped with a pipe opening at the lower end of its side wall, and the pipe connected to the pipe opening leads to the top opening of the sulfur settling tank 12.

[0067] During the reaction, the desulfurized rich liquid produced in the desulfurization process of desulfurization tower 1 contains sulfur that has not settled in time and a small amount of acidic gas. The acidic gas exists in the form of bubbles, and the surface of the bubbles carries reaction liquid such as alcohol amines. The desulfurized rich liquid produced by the desulfurization reaction carries the bubbles and sulfur and flows through the pipeline between desulfurization tower 1 and sulfur settling tank 12 to sulfur settling tank 12 by overflow. In sulfur settling tank 12, the desulfurized rich liquid and sulfur are separated under the action of gravity.

[0068] According to the present invention, a port is opened at the upper end of the side wall of the sulfur settling tank 12, and the pipe connected at the port is connected to the regeneration tower 2.

[0069] In this invention, the regeneration tower 2 includes a cavity at both ends through which gas or liquid can flow. The cavity contains desulfurization rich liquid, and the outer wall of the cavity is equipped with a temperature control device to provide a heat source for the cavity of the regeneration tower 2. The bottom of the regeneration tower 1 is connected to the regeneration gas pipe 13, and the regeneration gas passes through the desulfurization rich liquid from bottom to top. The regeneration gas pipe 13 is also connected to a gas flow meter 8 to monitor the regeneration gas flow in real time, so that the regeneration reaction is controllable.

[0070] As the desulfurization reaction proceeds, more Fe... 3+ Gradually transforms into Fe 2+ When the desulfurization efficiency decreases, the desulfurized rich liquid separated in the sulfur settling tank 12 is introduced into the regeneration tower 2 with regeneration gas to regenerate the desulfurizing agent. The regeneration gas is oxygen or air.

[0071] In this invention, under the same inlet flow conditions, the pure oxygen concentration is 99.99%, and the oxygen concentration in the air is 21%. Because the desulfurizer uses air as the regeneration gas, its regeneration rate is relatively slow, and due to Fe... 2+ The presence of Fe makes complete regeneration impossible; desulfurizers use pure oxygen as the regeneration gas, and after regeneration, only trace amounts of Fe remain in the system. 2+ It exists in the system, enabling the complete regeneration of the desulfurizing agent.

[0072] According to the present invention, during the regeneration process, regeneration gas is introduced through the regeneration gas pipe 13, and the flow rate of the regeneration gas is controlled by the gas flow meter 8 to be 10-200 mL / min, preferably 20-150 mL / min, and more preferably 50-70 mL / min.

[0073] In this invention, if the gas flow rate is too fast, the residence time of the desulfurizing agent to be regenerated in the regeneration gas is reduced, and the regeneration effect becomes worse. Within the above-mentioned regeneration gas flow rate range, the desulfurizing agent regeneration effect is the best.

[0074] In this invention, the regeneration temperature is controlled to be 10–70°C, preferably 20–60°C, and more preferably 35–45°C, by a temperature control device connected to the outer wall of the regeneration tower 2 chamber. According to this invention, excessively high regeneration temperatures are detrimental to the dissolution of oxygen in ionic liquids. Within the temperature range of 10–70°C, oxygen reacts with Fe… 2+ It has a fast reaction rate and suitable oxygen solubility, resulting in the best regeneration efficiency.

[0075] Furthermore, in order to make the regeneration reaction more thorough, it is preferable to provide a glass frit 6 at the bottom of the regeneration tower 2. When the regeneration gas passes through the glass frit 2, it is broken into small bubbles, thereby increasing the reaction interface.

[0076] During the reaction, the desulfurized rich liquor carrying sulfur and gas bubbles undergoes phase separation in the sulfur settling tank 12. Under gravity, the sulfur settles at the bottom of the sulfur settling tank 12. The desulfurized rich liquor overflows into the regeneration tower 2 through the port at the upper end of the side wall of the sulfur settling tank 12. Under the action of the regeneration gas, the H₂ in the desulfurized rich liquor... + It reacts with oxygen in the regenerated gas to produce water, Fe 2+ Oxidized to Fe 3+ The desulfurized rich liquor is converted into desulfurized lean liquor, i.e., desulfurizing agent, thus realizing the regeneration of the desulfurizing agent.

[0077] According to the present invention, a gas pipe is also connected to the top of the regeneration tower 2, one end of which is connected to a peristaltic pump 11, and the other end is inserted below the surface of the desulfurization lean liquid. The other end of the peristaltic pump is connected to the upper opening of the side wall of the desulfurization tower 1.

[0078] During the reaction, the regenerated desulfurizing agent in regeneration tower 2, i.e., the desulfurization lean liquid, is transported to desulfurization tower 1 under the power of peristaltic pump 11, so as to realize the regeneration and utilization of the desulfurizing agent.

[0079] According to the present invention, the desulfurization of H2S and the regeneration of the desulfurizing agent are achieved by using a desulfurization device, and this cycle is repeated repeatedly, which is very suitable for industrial production.

[0080] In a preferred embodiment, a mixture of 1-butyl-3-methylimidazolium ferric chloride, polyethylene glycol dimethyl ether, and N-methyldiethanolamine is used as a desulfurizing agent. Desulfurization and regeneration are carried out in the aforementioned desulfurization device. As the reaction proceeds, the enriched desulfurization solution formed in desulfurization tower 1 contains H+ due to its enrichment. + As concentration increases, N-methyldiethanolamine binds to H... +The polarity increases, and it separates to form an alcoholamine phase liquid film 4. Below the alcoholamine phase liquid film is an iron-based ionic liquid phase 3. Because the sulfur generated in the reaction does not settle in time, the desulfurization-rich liquor carrying sulfur and bubbles overflows into the sulfur settling tank 12. Sulfur 14 settles to the bottom of the sulfur settling tank 12 under gravity. The desulfurization-rich liquor gradually separates into phases: the upper phase is the alcoholamine phase liquid film 4, and the lower phase is the iron-based ionic liquid phase 3. The desulfurization-rich liquor above sulfur 14 continues to overflow into the regeneration tower 2 for regeneration. During the regeneration process, H… + It reacts with oxygen to produce water; H in the alcoholamine liquid film + As the concentration decreases, the upper phase of the desulfurization liquid, namely the amine phase liquid film, disappears, and the rich desulfurization liquid changes from a two-phase to a homogeneous phase, realizing cyclic phase change desulfurization. Figure 1 As shown.

[0081] The invention will be further illustrated below with examples.

[0082] Example

[0083] In the examples described below, the raw materials for synthesizing the iron-based ionic liquid, N-methylimidazolium, were purchased from Shanghai Sanwei Co., Ltd., n-butane chloride was purchased from Beijing Yili Chemical Co., Ltd., ferric chloride hexahydrate was purchased from Fuchen (Tianjin) Chemical Reagent Co., Ltd., anhydrous ferric chloride, polyethylene glycol dimethyl ether, polyethylene glycol, N-methyldiethanolamine, diethylaminoethanol, and diethanolamine were all purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., and H2S was purchased from Beijing Yongsheng Gas Co., Ltd.

[0084] Example 1

[0085] Chlorobutane and N-methylimidazole were mixed in a 50 L reactor at a molar ratio of 1.05:1 and stirred at 70 °C for 72 h to prepare BmimCl. BmimCl was washed with an equal volume of ethyl acetate to remove impurities. After thorough mixing, the mixture was allowed to stand and separate into layers; the upper layer was ethyl acetate, and the lower layer was BmimCl. This washing process was repeated 3–5 times. The residual ethyl acetate was evaporated from the washed BmimCl at 80 °C using a rotary evaporator. The evaporated BmimCl was then placed in a vacuum drying oven and dried at 80 °C under vacuum for 24 h to obtain 1-butyl-3-methylimidazole chloride (BmimCl). BmimCl and FeCl3·6H2O were mixed in a molar ratio of 1:2 and stirred at room temperature for 24 h. After standing and separating into layers, the upper layer was the organic phase, and the lower layer was the aqueous phase. The organic phase was then placed in a vacuum drying oven and dried at 80 °C under vacuum for 24 h to obtain 1-butyl-3-methylimidazole ferric chloride.

[0086] 10g of 1-butyl-3-methylimidazolium ferric chloride (Fe-IL), 5g of polyethylene glycol dimethyl ether (NHD), and 0.5g of N-methyldiethanolamine (MDEA) prepared above were mixed and shaken to obtain Fe-IL / NHD / MDEA desulfurizing agent.

[0087] To verify the recycling effect of Fe-IL / NHD / MDEA desulfurizer, the desulfurization reaction and the regeneration reaction of Fe-IL / NHD / MDEA desulfurizer were operated independently, specifically as follows:

[0088] 1) Desulfurization

[0089] The above Fe-IL / NHD / MDEA desulfurizing agent is loaded into Figure 1 The desulfurization tower 1 shown is filled with a mixed gas of 1% H2S and 99% N2 by volume through a gas supply device 7 to carry out a desulfurization reaction. The desulfurization conditions are set at 10,000 ppm H2S. The gas flow rate is controlled at 30 mL / min by a gas flow meter 8, and the reaction temperature is set at 30°C by a temperature control device.

[0090] During the desulfurization process, as the reaction proceeds, the desulfurization system in desulfurization tower 1 separates into two phases: the upper phase is the MDEA phase liquid film 4, and the lower phase is the iron-based ionic liquid phase 3.

[0091] The desulfurized rich liquid generated in desulfurization tower 1 carries sulfur and bubbles and overflows into sulfur settling tank 12. Sulfur 14 settles to the bottom of sulfur settling tank 12 under the action of gravity. The desulfurized rich liquid gradually separates into phases, with the upper phase being MDEA phase liquid film 4 and the lower phase being iron-based ionic liquid phase 3.

[0092] During the reaction, the concentration of H2S at 9 sampling ports was detected using a gas chromatograph (GC-7820, manufactured by Beijing Zhongke Huifen Instrument Co., Ltd.).

[0093] 2) Regeneration

[0094] Collect the rich desulfurization liquid and place it into the cavity of regeneration tower 2. Introduce oxygen into regeneration tower 2 at a flow rate of 50 mL / min through gas flow meter 8. Control the regeneration temperature to 40℃ through temperature control device to achieve one-time regeneration of Fe-IL / NHD / MDEA desulfurizer.

[0095] After one regeneration cycle, the regenerated Fe-IL / NHD / MDEA desulfurizer is reloaded. Figure 1In the cavity of desulfurization tower 1 shown, desulfurization and regeneration are carried out, completing the secondary regeneration of the Fe-IL / NHD / MDEA desulfurizing agent. This process of regeneration and recycling of the Fe-IL / NHD / MDEA desulfurizing agent is repeated 6 times. During each desulfurization cycle, the H2S concentration collected at sampling port 9 is 0, proving that the H2S desulfurization efficiency is 100%. The results of the cyclic desulfurization efficiency are as follows: Figure 2 As shown.

[0096] Example 2

[0097] The Fe-IL / NHD / MDEA desulfurizing agent was prepared in the same manner as in Example 1, and the regeneration and recycling process of the Fe-IL / NHD / MDEA desulfurizing agent was carried out 6 times, the difference being: Figure 1 The tail gas absorption device 10 is replaced with a container containing sodium hydroxide solution. A pipe is connected to the sampling port 9 and inserted below the liquid surface of the container containing sodium hydroxide solution to collect the tail gas HCl. After the reaction is completed, the amount of HCl contained in the gas is detected by an ion chromatograph (ICS-600, manufactured by Thermo Fisher Scientific). The result is 0, thus the number of HCl moles released by 1 mol Fe-IL during the desulfurization process is 0 mol.

[0098] Example 3

[0099] The Fe-IL / NHD / MDEA desulfurizer was prepared in the same manner as in Example 1. The desulfurizer was also recycled in a manner similar to that in Example 1, except that desulfurization and regeneration were continuous cycles, specifically:

[0100] The above Fe-IL / NHD / MDEA desulfurizing agent is loaded into Figure 1 The desulfurization tower 1 shown is filled with a mixed gas of 1% H2S and 99% N2 by volume through a gas supply device 7 to carry out a desulfurization reaction. The desulfurization conditions are set at 10,000 ppm H2S. The gas flow rate is controlled at 30 mL / min by a gas flow meter 8, and the reaction temperature is set at 30°C by a temperature control device.

[0101] The desulfurized rich liquid generated in desulfurization tower 1, carrying sulfur and bubbles, overflows into sulfur settling tank 12. Sulfur 14 settles to the bottom of sulfur settling tank 12 under gravity. The desulfurized rich liquid continues to overflow into regeneration tower 2, where the Fe-IL / PEG / MDEA desulfurizing agent is regenerated under the action of oxygen. Oxygen enters the cavity of regeneration tower 2 through regeneration gas pipe 13, and the flow rate is controlled at 50 mL / min by gas flow meter 8. The regeneration temperature is controlled at 40℃ by temperature control device. Continuous desulfurization is performed for 48 hours. During the desulfurization process, the H2S concentration collected at sampling port 9 is 0, proving that the H2S desulfurization efficiency is 100%.

[0102] Example 4

[0103] Iron-based ionic liquid (Fe-IL) was prepared in the same manner as in Example 1. The desulfurizing agent was recycled in a manner similar to that in Example 3, except that:

[0104] 18g of the iron-based ionic liquid (Fe-IL), 7g of polyethylene glycol (PEG), and 1g of N-methyldiethanolamine (MDEA) prepared above were mixed and shaken to obtain the Fe-IL / PEG / MDEA desulfurizing agent.

[0105] A mixture of 1% H2S and 99% N2 (by volume) was introduced into the Fe-IL / PEG / MDEA desulfurizing agent for desulfurization reaction. The desulfurization conditions were set as follows: 10,000 ppm H2S, a gas flow rate of 30 mL / min, and a reaction temperature of 30°C. During regeneration, the oxygen flow rate was 60 mL / min, and the regeneration temperature was 35°C. After 48 hours of continuous desulfurization, the H2S concentration collected at sampling port 9 was 0, demonstrating a 100% desulfurization efficiency.

[0106] Example 5

[0107] Iron-based ionic liquid (Fe-IL) was prepared in the same manner as in Example 1, and the desulfurizer was recycled in a manner similar to that in Example 3, except that:

[0108] 16g of the iron-based ionic liquid (Fe-IL), 6g of polyethylene glycol dimethyl ether (NHD), and 1g of diethylaminoethanol (DEEA) were prepared and shaken to obtain the Fe-IL / NHD / DEEA desulfurizing agent.

[0109] A mixture of 1% H2S and 99% N2 (by volume) was introduced into the Fe-IL / NHD / DEEA desulfurizing agent for desulfurization. The desulfurization conditions were set as follows: 10,000 ppm H2S, a gas flow rate of 30 mL / min, and a reaction temperature of 50°C. During regeneration, the oxygen flow rate was 60 mL / min, and the regeneration temperature was 35°C. After 48 hours of continuous desulfurization, the H2S concentration collected at sampling port 9 was 0, demonstrating a 100% desulfurization efficiency.

[0110] Example 6

[0111] Iron-based ionic liquid (Fe-IL) was prepared in the same manner as in Example 1, and the desulfurizer was recycled in a manner similar to that in Example 3, except that:

[0112] 20g of the iron-based ionic liquid (Fe-IL), 8g of polyethylene glycol (PEG), and 1g of diethanolamine (MEA) prepared above were mixed and shaken to obtain the Fe-IL / PEG / MEA desulfurizing agent.

[0113] A mixture of 1% H2S and 99% N2 (by volume) was introduced into the Fe-IL / PEG / MEA desulfurizing agent for desulfurization. The desulfurization conditions were set as follows: 10,000 ppm H2S, a gas flow rate of 30 mL / min, and a reaction temperature of 50°C. During regeneration, the oxygen flow rate was 50 mL / min, and the regeneration temperature was 50°C. After 48 hours of continuous desulfurization, the H2S concentration collected at sampling port 9 was 0, demonstrating a 100% desulfurization efficiency.

[0114] Comparative Example

[0115] Comparative Example 1

[0116] Iron-based ionic liquid (Fe-IL) was prepared in the same manner as in Example 1. Then, 10g of Fe-IL, 5g of polyethylene glycol dimethyl ether (NHD), and 0.1g of N-methyldiethanolamine (MDEA) were mixed and shaken to obtain Fe-IL / NHD / MDEA desulfurizing agent. The desulfurizing agent was recycled in the same manner as in Example 3, and desulfurization was carried out continuously for 48h. During the desulfurization process, the H2S concentration was collected at sampling port 9.

[0117] Comparative Example 2

[0118] Iron-based ionic liquid (Fe-IL) was prepared in the same manner as in Example 1. Then, 10 g of Fe-IL, 5 g of polyethylene glycol dimethyl ether (NHD), and 0.1 g of N-methyldiethanolamine (MDEA) were mixed and shaken to obtain the Fe-IL / NHD / MDEA desulfurizing agent. Desulfurization was achieved in the same manner as in Example 2, and the molar amount of HCl in the tail gas was measured. It was found that 1 mol of Fe-IL released 108 × 10⁸ moles of HCl during the desulfurization process. -6 mol.

[0119] Comparative Example 3

[0120] Iron-based ionic liquid (Fe-IL) was prepared in the same manner as in Example 1. Then, 2g of Fe-IL and 1g of polyethylene glycol dimethyl ether (NHD) were mixed and shaken to obtain Fe-IL / NHD desulfurizing agent. The desulfurizing agent was recycled in the same manner as in Example 2 and desulfurized continuously for 48h. The H2S concentration was collected at sampling port 9 during the desulfurization process.

[0121] Comparative Example 4

[0122] Iron-based ionic liquid (Fe-IL) was prepared in the same manner as in Example 1. Then, 10 g of Fe-IL, 5 g of polyethylene glycol dimethyl ether (NHD), and 0.1 g of N-methyldiethanolamine (MDEA) were mixed and shaken to obtain the Fe-IL / NHD / MDEA desulfurizing agent. Desulfurization was achieved in the same manner as in Example 2, and the molar amount of HCl in the tail gas was measured. It was found that 1 mol of Fe-IL released 1000 × 10⁻⁶ moles of HCl during the desulfurization process. -6 mol.

[0123] Experimental Example

[0124] Experimental Example 1

[0125] The desulfurization curves of Example 3 and Comparative Examples 1 and 3 after 48 hours are as follows: Figure 3 As shown in (a), the comparison chart of HCl content in the tail gas after desulfurization is as follows: Figure 3 As shown in (b), the desulfurization efficiency and sulfur capacity of the desulfurizing agent prepared after the addition of MDEA are significantly improved, especially the desulfurizing agent in Example 1, which still has a desulfurization efficiency of 100% after 48 hours of desulfurization; and the molar amounts of HCl and Fe-IL in the tail gas in Comparative Example 4 are as high as 1000, while the molar amounts of HCl and Fe-IL in the tail gas in Example 2 are 0, indicating that the addition of MDEA not only improves the sulfur capacity of Fe-IL / NHD desulfurizing agent, but also inhibits the escape of HCl in the system.

[0126] Experimental Example 2

[0127] The Fe-IL / NHD / DEEA desulfurizer (initial desulfurizer) prepared in Example 1 and the Fe-IL / NHD / DEEA desulfurizer (regenerated desulfurizer) after the 6th regeneration were characterized, and their infrared spectra are shown below. Figure 4 As shown in the figure, the infrared spectrum of the Fe-IL / NHD / DEEA desulfurizing agent regenerated from the desulfurization rich solution is basically the same as that of the Fe-IL / NHD / DEEA desulfurizing agent before desulfurization, indicating that the structure of the desulfurization solution has not changed after desulfurization and regeneration, and it has good reusability.

[0128] Experimental Example 3

[0129] The Fe-IL / NHD / DEEA desulfurizer prepared in Example 1 was cyclically regenerated 12 times according to the method described in Example 1. The initially prepared Fe-IL / NHD / DEEA desulfurizer (initial desulfurizer) and the desulfurizer from the 12th cycle (regenerated desulfurizer) were characterized, and their thermogravimetric diagrams are shown below. Figure 5 As shown in the figure, the desulfurizing agent still has good thermal stability after 12 cycles of desulfurization.

[0130] Experiment Example 4

[0131] The sulfur, the desulfurization product from Example 1, was characterized by its XRD pattern as shown below. Figure 6 As shown in the figure, the obtained sulfur product is orthorhombic.

[0132] The present invention has been described in detail above with reference to preferred embodiments and exemplary examples. However, it should be noted that these specific embodiments are merely illustrative explanations of the invention and do not constitute any limitation on the scope of protection of the invention. Various improvements, equivalent substitutions, or modifications can be made to the technical content and embodiments of the present invention without departing from the spirit and scope of protection of the invention, and all such modifications fall within the scope of protection of the present invention. The scope of protection of the present invention is defined by the appended claims.

Claims

1. A desulfurizing agent, characterized in that, The desulfurizing agent can achieve 100% desulfurization after being regenerated and recycled more than 6 times, and its sulfur capacity can reach more than 40g / L. The desulfurizing agent includes an iron-based ionic liquid, a co-solvent, and an acid control agent. The iron-based ionic liquid is an imidazole-based iron-based ionic liquid; the co-solvent is an alkyl polyether polyol; and the acid control agent is a H+-based liquid. + Amine compounds with strong binding ability, The weight ratio of iron-based ionic liquid, co-solvent, and acid control agent in the desulfurizing agent is (15-26):(3-13):(0.5-1.5).

2. The desulfurizing agent according to claim 1, characterized in that, The weight ratio of iron-based ionic liquid, co-solvent, and acid control agent in the desulfurizing agent is (15-20):(5-9):(1.0-1.5).

3. A method for desulfurization using iron-based ionic liquid oxidation, characterized in that, The method involves iron-based ionic liquid oxidation desulfurization in a desulfurization device, which includes a desulfurization tower (1) and a regeneration tower (2), and a sulfur settling tank (12) is connected between the desulfurization tower (1) and the regeneration tower (2) by a pipeline. The method includes: placing the desulfurizing agent according to claim 1 or 2 in a desulfurization tower (1), introducing H2S gas into the desulfurization tower (1), and starting the desulfurization device for desulfurization. The desulfurizing agent is prepared by mixing an iron-based ionic liquid, a co-solvent, and an acid control agent.

4. The method according to claim 3, characterized in that, The flow rate of H2S gas introduced is controlled to be 10-100 mL / min by a gas conveying device connected to the desulfurization tower (1).

5. The method according to claim 3, characterized in that, The desulfurized rich liquid carrying sulfur and bubbles generated by the desulfurization reaction in the desulfurization tower (1) is separated into phases in the sulfur settling tank (12). The sulfur settles at the bottom of the sulfur settling tank (12), and the desulfurized rich liquid overflows into the regeneration tower (2) through the port at the upper end of the side wall of the sulfur settling tank (12). Regeneration gas is introduced into the regeneration tower (2) to regenerate the desulfurizing agent.

6. The method according to claim 5, characterized in that, The flow rate of the regenerated gas is introduced through the regenerated gas pipe (13) connected to the lower end of the regeneration tower (2), and the flow rate of the regenerated gas is controlled to be 10-200 mL / min by the gas flow meter (8) connected to the regenerated gas pipe (13).

7. The method according to claim 6, characterized in that, The top of the regeneration tower (2) is connected to a gas pipe. One end of the gas pipe is connected to a peristaltic pump (11), and the other end is inserted below the surface of the regenerated desulfurizing agent in the regeneration tower (2). The other end of the peristaltic pump (11) is connected to the upper opening of the side wall of the desulfurization tower (1).

8. The method according to claim 6, characterized in that, The regenerated desulfurizing agent is transported to the desulfurization tower (1) under the power of the peristaltic pump (11), so as to realize the recycling of the regenerated desulfurizing agent.

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