A method for desulfurizing hydrogen sulfide and producing hydrogen based on iron-based ionic liquid

Abstract

The present invention discloses a method for desulfurizing hydrogen sulfide and producing hydrogen based on iron-based ionic liquids. By modifying traditional desulfurizers, a non-aqueous two-phase liquid-liquid system desulfurizer with weak acidity and catalytic oxidation functions is invented, which has high thermal stability and chemical stability, significantly improving the utilization rate of iron-based ionic liquids and the conversion rate of H2S. When the improved desulfurizer is used in the process of desulfurizing hydrogen sulfide and producing hydrogen, the conversion rate of H2S can reach 100%. It avoids the equipment corrosion and the destruction of the desulfurizer structure caused by the escape of HCl, realizes the full resource utilization of H2S, and improves the Fe 2+ regeneration efficiency and current efficiency, wherein the Fe 2+ regeneration efficiency is above 80%, and the current efficiency is above 60%.

Description

Technical Field

[0001] The present invention belongs to the field of oxidative desulfurization of metal-based ionic liquids, and particularly relates to a method for desulfurizing hydrogen sulfide and producing hydrogen based on iron-based ionic liquids. Background Art

[0002] Hydrogen sulfide is a highly toxic and harmful gas. It not only pollutes the environment, endangers human health, but also corrodes equipment in industrial processes and deactivates catalysts. Therefore, removing hydrogen sulfide is of great significance. As is well known, the sulfur element in hydrogen sulfide can be oxidized to produce by-product sulfur, which is widely used as food additives, pharmaceuticals, pesticides, etc.; the hydrogen element can be reduced to produce hydrogen, which can be directly used as energy or as a raw material for producing natural gas, thus realizing the full resource utilization of hydrogen sulfide. In 2015, the global sulfur production in the natural gas and petroleum industries alone was approximately 32.8 million tons / year, corresponding to a hydrogen production of 2.05 million tons / year.

[0003] Currently, the aqueous wet oxidation desulfurization process widely used in industry oxidizes the S element in H2S into elemental sulfur, while the hydrogen element regenerates into water through air. In fact, this is an inverse process of electrolyzing water and is a waste of energy. Thus, using electrolytic regeneration of the desulfurization solution, that is, hydrogen production can be achieved by indirectly electrolyzing hydrogen sulfide. The indirect electrolysis hydrogen sulfide hydrogen production process usually uses a proton exchange membrane / ceramic membrane to separate the anode area and the cathode area, and the electrolyte in the cathode area is an acid solution. Due to the low proton transfer efficiency, the utilization rate of H + produced by the oxidation of H2S is low. To maintain the stability of the current, acid needs to be continuously replenished during the electrolysis process, and the current efficiency is above 58%. If hydrogen sulfide is directly electrolyzed, there is also the problem that the oxidation product sulfur passivates the electrode and reduces the current efficiency.

[0004] As an environmentally friendly green solvent, ionic liquids have a wide liquid range, high thermal and chemical stability, low vapor pressure, non-volatility, strong solubility, adjustable structure, easy recovery, good conductivity, and a wide electrochemical window compared with traditional organic solvents, and have extensive applications in the fields of organic synthesis, catalysis, separation, and electrochemistry.

[0005] Metal-based ionic liquids combine the catalytic function of metal ions and the characteristics of ionic liquids, and have both a catalytic center and a gas absorption center. A large number of studies have shown that hydrophobic iron-based ionic liquids have advantages such as good thermal stability, high sulfur quality, and no secondary pollution in removing hydrogen sulfide. When compounded with organic solvents, the sulfur capacity of iron-based ionic liquids can be greatly improved. However, a large amount of HCl generated during the desulfurization process escapes, which not only causes equipment corrosion but also destroys the structure of the desulfurization solution, thereby reducing the subsequent desulfurization efficiency.

[0006] In recent years, the process of phase change absorption of acidic gases has received great attention due to its lower regeneration energy consumption. The widely used industrial process for CO2 absorption is the absorption of CO2 by an aqueous solution of 20 - 30 wt% monoethanolamine (MEA) at a temperature of 40 °C. The decarbonized rich solution is stripped to achieve CO2 desorption and regeneration of the decarbonizing agent (at a temperature of 120 - 140 °C), which has the problem of high regeneration energy consumption.

[0007] Although an increase in the MEA concentration can improve the CO2 absorption capacity and reduce part of the regeneration energy consumption, it will increase the hazards of equipment corrosion, amine degradation, and related emissions. Therefore, Hu et al. first proposed a liquid - liquid phase change absorption CO2 system, namely the alkanolamine - alcohol mixed system. After absorbing CO2, this system is divided into two phases, namely the CO2 - lean liquid phase and the CO2 - rich phase, with mass fractions of 80% and 20% respectively. Therefore, only 20% of the CO2 - rich phase needs to be stripped and regenerated to achieve CO2 recovery and recycling of the absorbent, while the CO2 - lean liquid phase does not need to be regenerated, greatly reducing the regeneration energy consumption.

[0008] The idea of the phase change system provides a new direction for the capture and resource utilization of HCl in the desulfurization process of metal - based ionic liquids. By phase transfer of the H+ generated during the oxidative desulfurization process, the capture and enrichment of HCl are realized, laying a foundation for the resource utilization of H + . Summary of the Invention

[0009] In order to solve the above problems, the inventor has intensively studied the hydrogen sulfide desulfurization process of iron - based ionic liquids and developed a method for hydrogen sulfide desulfurization and hydrogen production based on iron - based ionic liquids. By adjusting the composition and compatibility of the traditional desulfurizer, a non - aqueous two - phase liquid - liquid system desulfurizer with weak acidity and catalytic oxidation function is invented. It has high thermal stability and chemical stability, significantly improving the utilization rate of iron - based ionic liquids and the H2S conversion rate. Applying the improved desulfurizer to the hydrogen sulfide desulfurization and hydrogen production process can avoid the equipment corrosion and desulfurizer structure damage caused by the escape of HCl, achieve the complete conversion and full resource utilization of H2S, and improve the Fe 2+ regeneration efficiency and current efficiency. Among them, the Fe 2+ regeneration efficiency is more than 80%, and the current efficiency is more than 60%. The hydrogen sulfide desulfurization and hydrogen production method provided by the present invention obtains high - quality sulfur and has no secondary pollution, thus completing the present invention.

[0010] Specifically, the object of the present invention is to provide the following aspects:

[0011] (1) A desulfurizer, which is a non - aqueous two - phase liquid - liquid system desulfurization solution with weak acidity and catalytic oxidation function, including a cosolvent phase enriched with iron - based ionic liquids and an acid - control phase enriched with H + .

[0012] (2) A method for desulfurizing H2S and producing hydrogen based on iron-based ionic liquids, the method comprising: electrolyzing an acid control phase enriched with H + and Fe 2+ to regenerate a cosolvent phase enriched with iron-based ionic liquids and produce hydrogen.

[0013] (3) A desulfurization and hydrogen production device, the desulfurization and hydrogen production device comprising a phase separation tower and an electrolytic cell, the electrolytic cell comprising an anode region and a cathode region, and a cosolvent phase storage tank is connected between the phase separation and the anode region of the electrolytic cell through a pipeline.

[0014] The beneficial effects of the present invention include:

[0015] (1) The non-aqueous two-phase liquid-liquid system desulfurizer with weak acidity and catalytic oxidation function provided by the invention has high thermal stability and chemical stability. The protonation is achieved by using alkanolamine to absorb HCl gas, and the utilization rate of iron-based ionic liquids and the conversion rate of H2S are significantly improved by the compounding of polar solvents.

[0016] (2) The desulfurizer provided by the invention reduces the viscosity of the iron-based ionic liquid, and the addition of polar solvents during the desulfurization process improves the mass transfer efficiency of H2S and is beneficial to the separation of sulfur.

[0017] (3) According to the method for desulfurizing hydrogen sulfide and producing hydrogen based on iron-based ionic liquids provided by the present invention, the desulfurizer and the desulfurization system during the desulfurization process are weakly acidic, which improves the sulfur capacity and utilization rate of the iron-based ionic liquid, and the acid-binding ability is significantly enhanced, avoiding equipment corrosion and desulfurizer structure damage caused by the escape of HCl.

[0018] (4) According to the method for desulfurizing hydrogen sulfide and producing hydrogen based on iron-based ionic liquids provided by the present invention, the desulfurized rich liquid generated during the desulfurization process is mixed with the acid control phase to achieve the enrichment of H + and Fe 2+ in the acid control phase. After electrolysis, Fe 2+ in the acid control phase is electrocatalytically oxidized to Fe 3+ in the anode region, and H + is electrocatalytically reduced to H2 by proton membrane migration to the cathode region, realizing the full resource utilization of H2S.

[0019] (5) According to the method for desulfurizing hydrogen sulfide and producing hydrogen based on iron-based ionic liquids provided by the present invention, it has the advantages of high efficiency, simple operation, low energy consumption, high quality of sulfur obtained, and no secondary pollution.

[0020] (6) According to the method for desulfurizing hydrogen sulfide and producing hydrogen based on iron-based ionic liquids provided by the present invention, the desulfurization efficiency of H2S reaches more than 98%, even 100%, the regeneration efficiency of Fe 2+ is more than 80%, and the current efficiency is more than 60%. Description of the Drawings

[0021] Figure 1 Shows a schematic structural diagram of a desulfurization hydrogen production device according to a preferred embodiment of the present invention;

[0022] Figure 2 Shows a comparison chart of desulfurization efficiency and H2S conversion rate over time in Example 1;

[0023] Figure 3 -a shows a comparison chart of cyclic voltammograms in Experimental Example 1;

[0024] Figure 3 -b shows a comparison chart of LSV curves in Experimental Example 1. Detailed implementation manners

[0025] The present invention will be further described in detail below with reference to the drawings and embodiments. Through these descriptions, the features and advantages of the present invention will become clearer and more definite.

[0026] The special term "exemplary" here means "serving as an example, an embodiment or illustrative". Any embodiment described as "exemplary" here does not have to be construed as superior to or better than other embodiments. Although various aspects of the embodiments are shown in the drawings, the drawings do not have to be drawn to scale unless otherwise specified.

[0027] According to the present invention, the first aspect aims to provide a desulfurizer, which is a non-aqueous two-phase liquid-liquid system desulfurization liquid with weak acidity and catalytic oxidation function, including a cosolvent phase enriched with iron-based ionic liquid and an acid control phase enriched with H + .

[0028] According to the present invention, the volume ratio of the cosolvent phase enriched with iron-based ionic liquid to the acid control phase enriched with H + is (1-5):1, preferably (2-4):1, more preferably (2-3):1.

[0029] According to the present invention, the desulfurizer is weakly acidic, and the pH is preferably 2-6, more preferably 3-5.

[0030] According to the present invention, while the cosolvent phase enriched with iron-based ionic liquid absorbs H2S, it oxidizes H2S into elemental sulfur and generates H + ; the acid control phase enriched with H + can absorb the acidic gas HCl and provide H + for the electrolysis of the acid control phase.

[0031] According to the present invention, the distribution coefficient of HCl in the desulfurizer is 10-120, preferably 50-105, and the distribution coefficient of Fe 3+ in the desulfurizer is 20-100, preferably 30-80.

[0032] According to the present invention, the desulfurizer is prepared by mixing a protonated acid control agent with an iron-based ionic liquid, a co-solvent, and a polar solvent.

[0033] In the present invention, since an acid control agent such as alkanolamine has a strong binding ability with an acidic gas HCl and the binding product has good stability, therefore, H + is enriched in the acid control phase; since the iron-based ionic liquid is completely miscible with a co-solvent such as an alkyl polyether polyol, the iron-based ionic liquid is enriched in the co-solvent phase.

[0034] According to the present invention, in the desulfurization process, the co-solvent phase enriched with the iron-based ionic liquid in the desulfurizer oxidizes H2S to elemental sulfur and generates H + , and Fe 3+ in the co-solvent phase is oxidized to Fe 2+ . Since H + and Fe 2+ have a stronger binding ability with an acid control phase such as an alkanolamine phase, the phase transfer of H + and Fe 2+ is realized; the acid control phase enriched with H + and Fe 2+ is electrolyzed in an electrolytic cell to realize the electrocatalytic oxidation regeneration of Fe 2+ and hydrogen production from H + , thus realizing the full resource utilization of H2S.

[0035] According to the present invention, the protonated acid control agent is prepared by introducing an acidic gas such as HCl into the acid control agent to adjust the pH to near neutral.

[0036] Wherein, the pH is preferably 5-7, more preferably 5-6.

[0037] According to the present invention, the acid control agent is an organic base with a strong binding ability with H + , including amine compounds or nitrogen-containing heterocyclic compounds, preferably amine compounds, more preferably alkanolamines, such as N-methyldiethanolamine, diethanolamine, triethanolamine, ethanolamine, methylethanolamine, 2-amino-2-methyl-1-propanol, diethylaminoethanol.

[0038] According to the present invention, the alkanolamine is alkaline and can effectively adjust the pH of the system and reduce the corrosion of equipment caused by industrial processes. However, under alkaline conditions, the iron-based ionic liquid is prone to precipitation and denaturation. Therefore, it is preferred to protonate the alkanolamine, that is, by introducing an acidic gas such as HCl into the alkanolamine to adjust the pH to 5-7 to obtain a protonated alkanolamine, and then mixing it with the iron-based ionic liquid, the co-solvent, and the polar solvent to avoid the too strong alkalinity of the alkanolamine resulting in the denaturation of the iron-based ionic liquid.

[0039] The inventor of the present invention has found that alkanolamines have a relatively high boiling point, a relatively high HCl absorption capacity, and the combined product with HCl has good stability. By adjusting the degree of protonation of protonated alkanolamines, the acidity and basicity can be adjusted, which can prevent the escape of HCl in the desulfurization system and provide sufficient H for the electrolysis of the alkanolamine phase. + to achieve the reuse of H; + In addition, since protonated alkanolamines are weakly acidic after protonation, they can adjust the pH of the desulfurization system and avoid the strong acidity of the desulfurization system caused by H generated during the desulfurization process, + which may cause corrosion to the equipment in the industrial process. Finally, after protonated alkanolamines are mixed with a co-solvent, they phase-separate, while the binding ability between alkanolamines and H, + Fe 2+ is stronger, which can achieve the phase transfer of H and Fe during the desulfurization process, + Fe 2+ and then realize the electrolytic reuse of H and Fe. + Fe 2+

[0040] In the present invention, the iron-based ionic liquid is an imidazole-based iron-based ionic liquid, preferably a chloroimidazole-based iron-based ionic liquid, such as 1-ethyl-3-methylimidazolium tetrachloroferrate, 1-butyl-3-methylimidazolium tetrachloroferrate, 1-hexyl-3-methylimidazolium tetrachloroferrate, and more preferably 1-butyl-3-methylimidazolium tetrachloroferrate.

[0041] According to the preferred embodiment, the 1-butyl-3-methylimidazolium tetrachloroferrate is prepared by stirring and reacting the target ligand 1-butyl-3-methylchloroimidazole with ferric chloride at room temperature. Among them, the molar ratio of the 1-butyl-3-methylchloroimidazole to ferric chloride is (1-2):1.

[0042] Specifically: chlorinated alkanes such as n-butyl chloride are stirred and reacted with N-methylimidazole at 60-70 °C for 60-72 h, washed 3-5 times with an ester compound such as ethyl acetate to obtain 1-butyl-3-methylchloroimidazole, and then stirred and reacted with anhydrous FeCl3 at room temperature under an inert gas atmosphere for 12-16 h, or prepared by reacting the obtained 1-butyl-3-methylchloroimidazole with FeCl3·6H2O at room temperature for 24-26 h.

[0043] In the present invention, the imidazole-based iron-based ionic liquid can directly oxidize hydrogen sulfide to produce sulfur, avoiding the complex and cumbersome process operations such as continuously adding desulfurizing agents and adjusting the pH value caused by the decrease in the desulfurizing agent concentration and the change of the system pH value in the traditional wet desulfurization process,

[0044] Furthermore, imidazole chloride-based iron-based ionic liquids have good thermal stability, can maintain their physical and chemical properties at higher temperatures for recycling, and also have the commonalities of Bonsted acid and Lewis acid, enabling desulfurization under acidic conditions. Especially represented by 1-butyl-3-methylimidazolium tetrachloroferrate, the Fe in 1-butyl-3-methylimidazolium tetrachloroferrate 3+ / Fe 2+ has good redox reversibility. During the desulfurization process, Fe 3+ oxidizes hydrogen sulfide to sulfur and Fe 2+ , and Fe 2+ can be regenerated by oxidation and return to the Fe 3+ state for recycling.

[0045] In the present invention, due to the relatively high viscosity and acidity of the iron-based ionic liquid and the relatively low sulfur capacity, the sulfur capacity under working conditions is much smaller than its theoretical sulfur capacity, which limits the high-efficiency hydrogen sulfide absorption ability of the iron-based ionic liquid.

[0046] In the present invention, by introducing a cosolvent, the cosolvent has the advantage of excellent absorption effect on hydrogen sulfide, promotes the physical dissolution of hydrogen sulfide gas, and uses the high-concentration Fe in the iron-based ionic liquid 3+ to oxidize H2S to form elemental sulfur, achieving the purpose of efficient absorption and desulfurization of H2S.

[0047] According to the present invention, the cosolvent is a weakly basic and low-viscosity organic solvent, preferably polyether polyol, such as phenolic polyether polyol, amine polyether polyol, sugar polyether polyol, sorbitol polyether polyol, alkyl polyether polyol, and more preferably alkyl polyether polyol, such as dimethyl polyethylene glycol ether, polyethylene glycol.

[0048] In the present invention, using alkyl polyether polyol as the cosolvent can not only form a good miscible solvent system with the iron-based ionic liquid, enhance the desulfurization effect, but also has the function of defoaming. A large amount of foam will not be generated during the desulfurization process, which not only avoids flooding but also eliminates the need to add a defoaming agent during the reaction process, and the desulfurization reaction is mild.

[0049] According to the present invention, the polar solvent is a polar solvent with low viscosity and can activate Fe 3+ , such as: 1,3-dimethyl-2-imidazolidinone, N,N-dimethylformamide, N,N-dimethylacetamide.

[0050] According to the present invention, the polar solvent has good miscibility with the iron-based ionic liquid, does not change the chemical composition of the iron-based ionic liquid, does not affect the process of converting H2S into S elemental, and the density of the mixed system obtained after being miscible with the iron-based ionic liquid is the same as the density of solid sulfur (2.36 g·mL -1 ) or the density of molten sulfur (1.80 g·mL-1 ) There is a significant difference, which is convenient for the separation of elemental sulfur produced and promotes the desulfurization process.

[0051] According to the present invention, the weight ratio of the iron-based ionic liquid, co-solvent, polar solvent, and acid controller is (0.3 - 2):(0.6 - 1.8):(0.1 - 1.2):1, preferably (0.5 - 1.5):(1 - 1.8):(0.12 - 0.9):1, and more preferably (1 - 1.25):(1.25 - 1.5):(0.5 - 0.75):1.

[0052] According to the present invention, the constructed desulfurizer is weakly acidic, the content of the iron-based ionic liquid is greatly reduced, and the sulfur capacity and utilization rate of the iron-based ionic liquid are significantly improved; the acid-binding ability of the constructed desulfurizer is significantly enhanced, reducing the influence of equipment corrosion, environmental pollution, and the destruction of the iron-based ionic liquid structure caused by the escape of HCl.

[0053] According to the present invention, the second aspect aims to provide a method for oxidative desulfurization and hydrogen production using a desulfurizer, and the method includes: electrolyzing the acid control phase enriched with H + and Fe 2+ to realize the regeneration of the co-solvent phase enriched with the iron-based ionic liquid and hydrogen production.

[0054] In a preferred embodiment, the method for H2S desulfurization and hydrogen production based on the iron-based ionic liquid performs desulfurization and hydrogen production in a desulfurization and hydrogen production device, and the desulfurization and hydrogen production device includes a phase separation tower 3 and an electrolytic cell 4. The electrolytic cell 4 includes an anode region 41 and a cathode region 42. A co-solvent phase storage tank 5 is connected between the phase separation tower 3 and the anode region 41 of the electrolytic cell 4 through a pipeline.

[0055] Furthermore, the desulfurization and hydrogen production device further includes an absorption tower 1, a sulfur settling tank 2, and an acid control phase storage tank 6. The cathode region 42 of the electrolytic cell 4 is connected to the acid control phase storage tank 6, and a sulfur settling tank 2 is connected between the absorption tower 1 and the phase separation tower 3.

[0056] According to the present invention, the bottom or side wall of the phase separation tower 3 is provided with a co-solvent phase outlet 33, which is connected to a pump between the absorption tower 1. On the side wall of the phase separation tower 3, that is, at the acid control phase part enriched with H + there are an acid control phase inlet 31 and an acid control phase outlet 32, and the acid control phase inlet 31 is located above the acid control phase outlet 32.

[0057] At the beginning of the reaction, the desulfurizer is located in the phase separation tower 3. When the volume of the co-solvent phase enriched with the iron-based ionic liquid is greater than the volume of the acid control phase enriched with H + the acid control phase enriched with H +The acid control phase is located above the cosolvent phase enriched with iron-based ionic liquid. At this time, the cosolvent phase outlet 33 is located at the bottom or the lower end of the side wall of the phase separation tower 3, and the acid control phase inlet 31 and the acid control phase outlet 32 are located at the upper end of the side wall of the phase separation tower 3; conversely, the enriched H + The acid control phase is located below the cosolvent phase enriched with iron-based ionic liquid. At this time, the cosolvent phase outlet 33 is located at the upper end of the side wall of the phase separation tower 3, and the acid control phase inlet 31 and the acid control phase outlet 32 are located at the lower end of the side wall of the phase separation tower 3.

[0058] According to the present invention, the phase separation tower 3 is provided with a device for introducing the desulfurized rich liquid, preferably a spraying device 34 or a pipe inserted below the liquid level of the acid control phase. Among them, the desulfurized rich liquid is a suspended desulfurized rich liquid enriched with H + and Fe 2+ produced by the desulfurization reaction in the absorption tower 1. When the acid control phase is located above the cosolvent phase, the device for introducing the desulfurized rich liquid into the phase separation tower 3 is a spraying device 34 or a pipe inserted below the liquid level of the acid control phase, preferably a spraying device 34; when the acid control phase is located below the cosolvent phase, the device for introducing the desulfurized rich liquid into the phase separation tower 3 is a pipe inserted below the liquid level of the acid control phase.

[0059] According to the present invention, the cosolvent phase storage tank 5 is provided with pipe openings, preferably 2. One of the pipe openings is connected to the anode region 41 of the electrolytic cell 4 through a pipe, and the other pipe opening is connected to the acid control phase inlet 31 at the upper end of the side wall of the phase separation tower 3 through a pipe, and the pipe connected to the acid control phase inlet 31 at the upper end of the side wall of the phase separation tower 3 is inserted below the liquid level of the cosolvent phase storage tank 5. A pump is connected between the cosolvent phase storage tank 5 and the phase separation tower 3 to facilitate the transfer of the liquid phase in the cosolvent phase storage tank 5 into the phase separation tower 3 under the power of the pump.

[0060] According to the present invention, the acid control phase storage tank 6 is provided with a liquid inlet 61 and a liquid outlet 62.

[0061] In the present invention, the anode region 41 and the cathode region 42 of the electrolytic cell 4 are separated by a supported liquid membrane.

[0062] Among them, the electrode materials of the anode region 41 and the cathode region 42 are different. The anode region 41 uses a metal-based alloy material such as a Ti-based material or a non-metallic material such as a carbon-based material as the electrode material, and the cathode region 42 uses a Pt sheet, a metal-based alloy material or a non-metallic material such as a carbon-based material as the electrode material.

[0063] According to the present invention, the supported liquid membrane is not limited to any proton exchange membrane on the market that can pass anions and cations, such as Nafion 117 proton membrane.

[0064] In the present invention, the upper and lower ends of the side walls of the anode region 41 and the cathode region 42 of the electrolytic cell 4 are respectively provided with pipe connection ports, such asFigure 1 as shown

[0065] Among them, the pipeline connection port at the upper end of the side wall of the anode region 41 of the electrolytic cell 4 is connected to the cosolvent phase storage tank 5, the pipeline connection port at the lower end of the side wall of the anode region 41 is connected to the acid control phase outlet 32 of the phase separation tower 3, the pipeline connection port at the upper end of the side wall of the cathode region 42 is connected to the liquid inlet 61 of the acid control phase storage tank 6, and the pipeline connection port at the lower end of the side wall of the cathode region 42 is connected to the liquid outlet 62 of the acid control phase storage tank 6.

[0066] Among them, the pipeline of the liquid outlet 62 is inserted below the liquid level of the acid control phase storage tank 6, and a pump is connected between the pipeline connection port at the lower end of the side wall of the anode region 41 and the liquid outlet 62 of the acid control phase storage tank 6, which is beneficial to pump the liquid phase in the acid control phase storage tank 6 into the anode region 41.

[0067] Furthermore, a pump is also connected between the pipeline connection port at the lower end of the side wall of the anode region 41 and the acid control phase outlet 32 of the phase separation tower 3, which is convenient to pump the acid control phase enriched with H + and Fe 2+ into the electrolytic cell 4 for electrolysis reaction.

[0068] Even further, a temperature control device is connected to the outside of the electrolytic cell 4 for controlling the electrolysis reaction temperature.

[0069] According to the present invention, the absorption tower 1 is a hollow cavity for gas and liquid circulation. The bottom of the desulfurization tower 1 is connected to a gas delivery device, so that the gas containing H2S passes through the liquid phase in the cavity from bottom to top. The liquid phase in the cavity is a cosolvent phase enriched with iron-based ionic liquid and a suspended desulfurized rich liquid enriched with H + and Fe 2+ produced by the desulfurization reaction. A temperature control device is connected to the outer wall of the cavity to provide heat for the cavity of the reactor 1. A spraying device 11 is provided at the upper end of the cavity of the absorption tower 1, and the spraying device 11 is connected to the cosolvent phase outlet 33 of the phase separation tower 3. The top of the desulfurization tower 1 is an air outlet, which is connected to a tail gas absorption device through a pipeline.

[0070] Among them, in order to increase the reaction interface, it is preferably provided with a glass sand core 12 at the bottom of the absorption tower 1. When the gas containing H2S passes through the glass sand core 12, it is divided into small bubbles. The pore diameter of the glass sand core 12 is 3.0 - 12 μm, preferably 4.5 - 9 μm, so as to improve the desulfurization efficiency.

[0071] According to the present invention, a pipeline port 13 connected to the desulfurized rich liquid inlet 21 of the sulfur settling tank through a pump is further provided at the lower end of the side wall of the phase separation tower.

[0072] According to the present invention, the sulfur settling tank 2 includes a desulfurized rich liquid inlet 21 and a desulfurized rich liquid outlet 22, wherein the desulfurized rich liquid outlet 22 is connected to a spraying device 34 in the phase separation tower 3 or a pipeline inserted below the acid control phase liquid level.

[0073] At the beginning of the reaction, first place the desulfurizer in the phase separation tower 3, and then introduce H2S gas into the absorption tower 1. The H + in the acid control phase is pumped into the electrolytic cell under the power of the pump. The H + enters the cathode region 42 through the supported liquid membrane and electrolyzes to generate H2. The solubilizing phase enriched with iron-based ionic liquid in the desulfurizer is sprayed into the absorption tower 1 through the spraying device 11 in the absorption tower 1 under the action of the pump. The Fe 3+ in the pumped liquid undergoes an oxidation-reduction reaction with H2S to generate desulfurized rich liquid enriched with H + and Fe 2+ Since sulfur is a solid phase with a large density, and due to the H2S gas introduced into the absorption tower 1, under the action of the gas flow, the sulfur has no time to settle and is suspended in the desulfurized rich liquid, forming a suspended desulfurized rich liquid enriched with H + and Fe 2+ which further enters the sulfur settling tank 2 under the action of the pump. The sulfur therein settles at the bottom of the sulfur settling tank 2 under the action of gravity, and the desulfurized rich liquid enriched with H + and Fe 2+ further enters the phase separation tower 3 in the form of spraying (when the solubilizing phase density is greater than the acid control phase density) or liquid flow (when the solubilizing phase density is less than the acid control phase density) through the spraying device 34 or the pipeline.

[0074] Among them, the sulfur settling tank 2 can also be an industrial centrifuge to separate sulfur from the desulfurized rich liquid by centrifugation.

[0075] Since H + and Fe 2+ have greater solubility in the acid control phase such as alkanolamine phase, they are extracted to the acid control phase through the solubilizing phase / acid control phase interface, resulting in the transformation of the desulfurized rich liquid enriched with H + and Fe 2+ into desulfurized lean liquid. At this time, the desulfurized lean liquid composition is a solubilizing phase enriched with Fe 3+ and is separated into two phases with the acid control phase. At this time, the acid control phase is enriched with H + and Fe 2+ .

[0076] The acid control phase enriched with H + and Fe 2+ enters the electrolytic cell 4 under the action of the pump along the acid control phase outlet 32. Fe 2+ undergoes an oxidation reaction in the anode region 41 and is reduced to Fe3+ ,H + enters the cathode region 42 along the proton membrane and undergoes a reduction reaction, being oxidized to H2.

[0077] The anode region 41 contains Fe 3+ in the acid control phase enters the cosolvent phase storage tank 5, and enters the phase separation tower 3 under the action of a pump. Due to the stronger binding ability of Fe 3+ with the cosolvent phase, Fe 3+ enters the cosolvent phase, and phase separation is completed again. The cosolvent phase containing Fe 3+ , that is, the cosolvent phase enriched with iron-based ionic liquid, is sprayed onto the absorption tower 1 along the cosolvent phase outlet 33 of the phase separation tower 3 under the action of a pump through the spraying device 11 for continuous oxidative desulfurization. H + in the cathode region 42 is oxidized to H2, and the remaining liquid acid control phase enters the acid control phase storage tank 6 through the pipeline connection at the upper end of the side wall of the cathode region 42, and then enters the cathode region 42 under the action of a pump, enters the anode region 41 along the supported liquid membrane, and enters the cosolvent phase storage tank 5 through the pipeline connection at the upper end of the side wall of the anode region 41, and then enters the phase separation tower 3, where it is miscible with the acid control phase during phase separation.

[0078] According to the present invention, the desulfurization and hydrogen production device connects the traditional absorption tower 1, phase separation tower 3, and electrolytic cell 1 to complete oxidative desulfurization and hydrogen production. The sulfur produced by the desulfurization reaction has high quality, does not cause secondary pollution, and the produced hydrogen is recycled, realizing the full resource utilization of H2S.

[0079] According to the present invention, when performing desulfurization and hydrogen production in the desulfurization and hydrogen production device, the method includes: placing the desulfurizer in the phase separation tower 3, introducing H2S gas into the absorption tower 1 5 - 10 minutes after starting the device operation. During the desulfurization process, the acid control phase enriched with H + and Fe 2+ is electrolyzed in the electrolytic cell 4 to realize the regeneration of the cosolvent phase enriched with iron-based ionic liquid and hydrogen production, and the cosolvent phase of the iron-based ionic liquid performs desulfurization in the absorption tower 1.

[0080] According to the present invention, the desulfurizer is prepared by mixing a protonated acid control agent and a cosolvent, standing, and then mixing with an iron-based ionic liquid and a polar solvent and standing.

[0081] According to the present invention, the volume concentration of H2S is between 0 and 10%.

[0082] According to the present invention, the desulfurization temperature of the desulfurization tower 1 is 10 - 90 °C, preferably 20 - 70 °C, and more preferably 25 - 60 °C.

[0083] According to the present invention, the temperature change and reaction time have a great influence on the desulfurization efficiency of the desulfurizer. The lower the temperature, the lower the desulfurization efficiency, but the higher the H2S conversion rate; as the temperature increases, the mass transfer of gas molecules in the ionic liquid becomes better, and the desulfurization ability of the iron-based ionic liquid in the desulfurizer is significantly improved, but the H2S conversion rate decreases. Moreover, as the reaction time prolongs, the H2S desulfurization efficiency and conversion rate decrease. When the reaction temperature is 10 - 90 °C, the desulfurization efficiency is above 98%; when the reaction time is within 1 h, the H2S conversion rate is above 90%.

[0084] In the present invention, the flow rate of the introduced H2S gas is 10 - 100 mL / min, preferably 15 - 70 mL / min, and more preferably 20 - 50 mL / min.

[0085] According to the present invention, increasing the gas flow rate will reduce the residence time of H2S in the desulfurizer, resulting in insufficient contact between H2S molecules and the ionic liquid, and further leading to a poor desulfurization effect. When the H2S gas flow rate is 10 - 100 mL / min, the desulfurization efficiency reaches above 98%, and even as high as 100%.

[0086] According to the present invention, the electrolysis temperature is 10 - 60 °C, preferably 20 - 60 °C, and more preferably 25 - 45 °C.

[0087] In the present invention, the electrolysis temperature is an important process technical condition for the stable operation of the electrolytic cell 4, directly affecting the operation status and process technical conditions of the electrolytic cell 4. When the electrolysis temperature is 10 - 60 °C, the current efficiency is high and the electrolysis reaction is stable.

[0088] According to the present invention, the H2S desulfurization efficiency is above 98%, preferably above 99%, and more preferably 100%; Fe 2+ The regeneration efficiency is above 80%, preferably above 90%, and more preferably above 95%; the current efficiency is above 60%, preferably above 70%, and more preferably above 75%.

[0089] According to the present invention, the third aspect aims to provide a desulfurization and hydrogen production device, which includes a phase separation tower 3 and an electrolytic cell 4. The electrolytic cell 4 includes an anode region 41 and a cathode region 42. A cosolvent phase storage tank 5 is connected between the phase separation tower 3 and the anode region 41 of the electrolytic cell 4 through a pipeline.

[0090] Furthermore, the desulfurization and hydrogen production device further includes an absorption tower 1, a sulfur settling tank 2, and an acid control phase storage tank 6. The cathode region 42 of the electrolytic cell 4 is connected to the acid control phase storage tank 6, and a sulfur settling tank 2 is connected between the absorption tower 1 and the phase separation tower 3.

[0091] Examples

[0092] The present invention will be further described below through specific examples. However, these examples are merely exemplary and do not impose any limitation on the protection scope of the present invention.

[0093] The sources of the reagents used in the following examples are as follows:

[0094]

[0095] Example 1

[0096] Chlorobutane and N-methylimidazole with a molar ratio of 1.05:1 were mixed in a 50 L reaction kettle, and stirred and reacted at 70 °C for 72 h to prepare BmimCl. BmimCl was washed with an equal volume of ethyl acetate to remove impurities. After thorough stirring, it was allowed to stand for layering. The upper layer was ethyl acetate, and the lower layer was BmimCl. It was continuously washed 3 to 5 times. The washed BmimCl was evaporated to remove the residual ethyl acetate at 80 °C using a rotary evaporator. The rotary-evaporated BmimCl was placed in a vacuum drying oven and dried at 80 °C under vacuum for 24 h to obtain 1-butyl-3-methylimidazolium chloride (BmimCl). BmimCl and FeCl3·6H2O were mixed at a molar ratio of 1:2, and stirred and reacted at room temperature for 24 h. After standing for layering, the upper layer was the organic phase, and the lower layer was the aqueous phase. The organic phase was placed in a vacuum drying oven and dried at 80 °C under vacuum for 24 h to obtain 1-butyl-3-methylimidazolium tetrachloroferrate liquid (BmimFeCl4 liquid).

[0097] Dry HCl gas was introduced into N-methyldiethanolamine (MDEA) to adjust the HCl concentration in MDEA to 1.0 - 3.0 mol / L to obtain protonated MDEA.

[0098] 10 mL of protonated MDEA was mixed with 20 mL of polyethylene glycol dimethyl ether (NHD), shaken evenly, then 10 mL of N,N-dimethylacetamide (DMAC) and 10 mL of the above-prepared BmimFeCl4 liquid (Fe-IL) were added thereto, shaken well, and allowed to stand for layering to prepare the NHD / DMAC / Fe-IL desulfurizer.

[0099] Adopt Figure 1 The desulfurization and hydrogen production device shown in the figure was used for the reaction. Among them, in the electrolytic cell 4, the anode region 41 used Ti as the electrode material, the cathode region 42 used a Pt sheet as the electrode material, and the proton membrane was a Nafion cation exchange membrane (produced by DuPont):

[0100] Place the above NHD / MDEA / Fe-IL desulfurizer in the phase separation tower 3, start the reaction device, and after 5 minutes, introduce a mixed gas with a volume fraction of 1% H2S and 99% N2 into the absorption tower 1. Control the gas flow rate at 30 mL / min, the reaction temperature at 30 °C, control the electrolysis temperature of the electrolytic cell 4 at 45 °C, and control the flow rate at the acid control phase inlet 31 of the phase separation tower 3 at 3 mL / min. The reaction lasts for 2 hours. After the reaction, measure Fe 2+ The regeneration efficiency is 80%, and the current efficiency is 68%.

[0101] During the reaction process, it is measured that the desulfurization efficiency of H2S at 0.5 h, 1 h, and 2 h is all 100%. The H2S conversion rate reaches 100% at 0.5 h of the reaction. As the reaction time extends, the H2S conversion rate decreases. The desulfurization efficiency and H2S conversion rate varying with time are as Figure 2 shown.

[0102] Among them, the H2S outlet concentration is measured by a gas chromatograph (model GC-7820, produced by Beijing Zhongke Huifen Instrument Co., Ltd.). The desulfurization efficiency of H2S is obtained from the formula (1 - C H2S出口浓度 / C H2S进口浓度 ) × 100%; the Fe 2+ concentration is measured by an oxidation-reduction potential titrator (model: 877 Titrino plus, produced by Metrohm AG, Switzerland). The Fe 2+ regeneration efficiency is obtained from the formula (1 - C Fe2+浓度 / C Fe2+初始浓度 ) × 100%; the H2S conversion rate is obtained from the formula Δn (Fe2+) / n (H2S吸收) × 100%; the current efficiency is obtained from Δn (Fe2+) F / Q × 100%.

[0103] Example 2

[0104] Prepare the BmimFeCl4 liquid (Fe-IL) in the same manner as in Example 1, and achieve desulfurization and hydrogen production in a similar manner to Example 1, with the differences being that

[0105] Mix 10 mL of protonated MDEA with 20 mL of polyethylene glycol (PEG), shake well, then add 10 mL of 1,3-dimethyl-2-imidazolidinone (DMI) and 10 mL of Fe-IL thereto, shake well, and let it stand for layering to prepare the PEG / MDEA / Fe-IL desulfurizer.

[0106] During the reaction, control the reaction temperature in the absorption tower 1 at 30 °C, control the electrolysis temperature of the electrolytic cell at 45 °C, and the reaction lasts for 2 hours.

[0107] The reaction is completed, and the desulfurization efficiency of H2S is measured to be 100%, and the Fe 2+ regeneration efficiency is 85%, and the current efficiency is 70%.

[0108] Example 3

[0109] BmimFeCl4 liquid (Fe-IL) is prepared in the same manner as in Example 1, and desulfurization and hydrogen production are achieved in a similar manner to Example 1, except that:

[0110] Dry HCl gas is introduced into diethanolamine (DEA) to adjust the HCl concentration in DEA to 1.0 - 3.0 mol / L, obtaining protonated DEA.

[0111] 10 mL of protonated DEA is mixed with 20 mL of NHD, shaken evenly, then 10 mL of N,N-dimethylacetamide (DMAC) and 10 mL of Fe-IL are added thereto, shaken well, and allowed to stand for layering to prepare the NHD / DEA / Fe-IL desulfurizer.

[0112] During the reaction, the reaction temperature of Absorber 1 is controlled at 40 °C, and the electrolysis temperature of the electrolytic cell is controlled at 45 °C, and the reaction lasts for 2 h.

[0113] The reaction is completed, and the desulfurization efficiency of H2S is measured to be 99%, and the Fe 2+ regeneration efficiency is 85%, and the current efficiency is 72%.

[0114] Example 4

[0115] BmimFeCl4 liquid (Fe-IL) is prepared in the same manner as in Example 1, and desulfurization and hydrogen production are achieved in a similar manner to Example 1, except that:

[0116] Dry HCl gas is introduced into diethylaminoethanol (DEEA) to adjust the HCl concentration in DEEA to 1.0 - 3.0 mol / L, obtaining protonated DEEA.

[0117] 10 mL of protonated DEEA is mixed with 20 mL of NHD, shaken evenly, then 10 mL of DMAC and 10 mL of Fe-IL are added thereto, shaken well, and allowed to stand for layering to prepare the NHD / DEEA / Fe-IL desulfurizer.

[0118] During the reaction, the reaction temperature of Absorber 1 is controlled at 30 °C, and the electrolysis temperature of the electrolytic cell is controlled at 40 °C, and the reaction lasts for 2 h.

[0119] The reaction is completed, and the desulfurization efficiency of H2S is measured to be 99%, and the Fe 2+ regeneration efficiency is 90%, and the current efficiency is 75%.

[0120] Comparative Example

[0121] Comparative Example 1

[0122] The NHD / Fe-IL desulfurizer was prepared in a manner similar to that of Example 1, except that: DMAC was not added, and desulfurization and hydrogen production were carried out in the same manner as in Example 1.

[0123] Experimental Example

[0124] Experimental Example 1

[0125] In Example 1 and Comparative Example 1, the comparative diagram of cyclic voltammograms on the surface of the Pt sheet electrode in the cathode region is as Figure 3 shown in -a, and the comparative LSV curve on the surface of the Pt sheet electrode in the cathode region is as Figure 3 shown in -b. It can be seen that the hydrogen evolution current density of the MDEA phase obtained by phase separation after adding the polar organic solvent DMAC is significantly increased, indicating that it is feasible to use DMAC as the electrolyte in the cathode region to achieve electrolytic hydrogen production.

[0126] The present invention has been described in detail above in combination with preferred embodiments and exemplary examples. However, it should be noted that these specific embodiments are only illustrative explanations of the present invention and do not constitute any limitation to the protection scope of the present invention. Without departing from the spirit and protection scope of the present invention, various improvements, equivalent replacements or modifications can be made to the technical content and its implementation manners of the present invention, and these all fall within the protection scope of the present invention. The protection scope of the present invention shall be subject to the appended claims.

Claims

1. A method for desulfurization of H2S and hydrogen production based on iron-based ionic liquids, the method comprising: Electrolyze the acid control phase enriched with H + and Fe 2+ to regenerate the solubilizing phase of the iron-based ionic liquid enriched and produce hydrogen, The described method is carried out in a desulfurization hydrogen production device, which includes a phase separation tower (3) and an electrolytic cell (4). The electrolytic cell (4) includes an anode region (41) and a cathode region (42). A cosolvent phase storage tank (5) is connected between the phase separation tower (3) and the anode region (41) of the electrolytic cell (4) through a pipeline; The desulfurization hydrogen production device further includes an absorption tower (1), a sulfur settling tank (2) and an acid control phase storage tank (6). The cathode region (42) of the electrolytic cell (4) is connected to the acid control phase storage tank (6), and a sulfur settling tank (2) is connected between the absorption tower (1) and the phase separation tower (3); The method includes: placing a desulfurizer in a phase separation tower (3), introducing H2S gas into an absorption tower (1), and during the desulfurization process, enriching H + and Fe 2+ in the acid control phase of the electrolytic cell (4) for electrolysis to realize the regeneration of the solubilizing phase enriched with iron-based ionic liquid and hydrogen production, and the solubilizing phase of the iron-based ionic liquid is used for desulfurization in the absorption tower (1); The desulfurizer is prepared by mixing a protonated acid controller with an iron-based ionic liquid, a co-solvent and a polar solvent. The protonated acid controller is prepared by introducing an acidic gas into an acid controller and adjusting the pH to 5-7. The acidic gas is HCl, and the acid controller is an organic base with strong binding ability to H + ; the iron-based ionic liquid is an imidazole-based iron-based ionic liquid; the co-solvent is a weakly basic and low-viscosity organic solvent; the polar solvent is a polar solvent with low viscosity and capable of activating Fe 3+ ; The desulfurizer is a non-aqueous two-phase liquid-liquid system desulfurization solution with weak acidity and catalytic oxidation functions, including a solubilizing phase enriched with iron-based ionic liquid and an acid control phase enriched with H + 2 2. According to the method described in claim 1, the solubilizing phase enriched with iron-based ionic liquid can absorb hydrogen sulfide gas, oxidize H2S to elemental sulfur, and generate H + ; the acid control phase enriched with H + can absorb HCl and provide H + .

3. According to the method described in claim 2, the distribution coefficient of HCl in the desulfurizer is 10 to 120, and Fe 3+ The distribution coefficient in the desulfurizer is 20 to 100.

4. A device for desulfurization and hydrogen production by the method of H2S desulfurization and hydrogen production based on iron-based ionic liquid according to any one of claims 1 to 3, characterized in that, The desulfurization hydrogen production device includes a phase separation tower (3) and an electrolytic cell (4). The electrolytic cell (4) includes an anode region (41) and a cathode region (42). A cosolvent phase storage tank (5) is connected between the phase separation (3) and the anode region (41) of the electrolytic cell (4) through a pipeline.

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