Ionic liquid anolyte and method for strengthening sulfur separation by using ionic liquid anolyte

Abstract

The invention discloses an ionic liquid anolyte and a method for intensifying sulfur separation, a functionalized ionic liquid is used as an absorbent and an electrolyte regulating agent, on one hand, hydrogen sulfide is efficiently absorbed, and on the other hand, the hydrogen sulfide electrolysis process is coupled. Gas absorption is directly carried out in an anode chamber, then absorption liquid is electrolyzed, sulfur is obtained from an anode, and hydrogen is prepared from a cathode. Sulfur generated at the anode can be separated out from the electrolyte, and precipitates are formed at the bottom of the electrolytic tank; meanwhile, as a novel green solvent, the ionic liquid has a wider electrochemical window and conductivity, so that the electrolytic reaction can be effectively promoted, and the hydrogen production rate of the cathode is greatly improved. According to the method, the absorption rate and the electrolytic reaction rate are high, the hydrogen production rate is higher than that of most systems using the electrocatalyst, sulfur can be self-precipitated in the electrolyte, redundant sulfur separation operation is not needed, the electrolyte can still be recycled after sulfur is filtered, and the method is environment-friendly and energy-saving. And efficient absorption of hydrogen sulfide and production of clean energy hydrogen are facilitated.

Description

Technical Field

[0001] The invention relates to the technical field of hydrogen sulfide absorption and conversion, and in particular to an ionic liquid anolyte enhanced hydrogen sulfide absorption-electrolysis coupling technology, specifically to an ionic liquid anolyte and a method for enhancing sulfur precipitation thereof. Background Art

[0002] Hydrogen sulfide (H 2 S) mainly comes from industrial production in refineries, natural gas and biogas. It is a toxic and harmful gas that needs to be removed from the environment or production process. However, H 2 The concentration of S is usually greater than several thousand mg / m3. In addition, due to the increase in heavy oil refining, it is expected that H 2 The production of S will increase, so it is necessary to remove toxic gas H from industrial production or the environment. 2 S. In industry, most H 2 S is processed by the Claus process, in which H 2 S is partially oxidized to S and H 2 O. The Claus process only results in the recycling of elemental sulfur (S), while elemental hydrogen (H) forms water and cannot be effectively utilized. Therefore, efficient removal and utilization of H in industry 2 S is still a huge challenge. Against this backdrop, renewable energy electrolysis hydrogen production, as an emerging industry technology, has a growing share year by year and has good development prospects. It is expected to account for more than 70% in 2050. Among them, water electrolysis technology is relatively mature, but from a cost perspective, the energy consumption of water electrolysis does not show a clear advantage over traditional processes. In addition, the current precious metal catalysts have disadvantages such as high cost and excessive power consumption. These unfavorable factors have hindered the development of water electrolysis hydrogen production technology. 2 The voltage required by S hydrogen production technology is much smaller than that of water electrolysis. It can not only eliminate pollution, but also produce sulfur as a by-product. It can be coupled with renewable energy and has the advantages of environmental governance, dual carbon emission reduction, and efficient resource utilization.

[0003] Conventional electrochemical decomposition of H 2 The S method is to electrolyze H 2 S or H 2 S alkaline absorption liquid, sulfur is generated at the anode, hydrogen is generated at the cathode, and the alkaline absorption liquid used is NaOH solution, NaHCO 3 Solution, Na 2 CO 3 However, the anode is passivated due to the deposition of sulfur, which makes direct electrolysis of H 2The development of S technology has been subject to certain restrictions. For this reason, some remedial measures have been proposed one after another: 1. Stirring to make the sulfur fall off the electrode; 2. Introducing organic vapor or adding benzene or toluene to the electrolyte to dissolve the sulfur; 3. Introducing high-temperature electrochemical methods to form sulfur vapor or liquid sulfur; 4. Controlling the ratio of alkaline electrolyte and hydrogen sulfide can form soluble polysulfides at the anode. However, the complexity of the system limits the scale of these measures. Although the direct electrolysis method is more energy efficient, the production of sulfur brings about separation and electrode contamination problems, the introduction of high-temperature electrochemical methods, the occurrence of side reactions, and the limited solubility of the polysulfides formed. 5. The indirect electrolysis method is due to the fact that H 2 S gas is absorbed, chemically oxidized to generate sulfur, and then the absorption liquid is electrolyzed, so the anode passivation problem caused by sulfur deposition can also be avoided. However, the absorption liquid is highly acidic and causes serious corrosion to the equipment. During the electrolysis process, due to the presence of oxidized ions, the cell voltage of the electrolytic cell will continue to increase, thereby reducing the current efficiency.

[0004] In addition, electrochemical methods can decompose H 2 Another limiting factor of S is the low hydrogen yield. To this end, many experts and scholars have developed a series of electrocatalysts to increase the reaction rate, such as WS 2 Nanosheet catalysts and N-doped graphene wrapped cobalt-nickel alloy catalysts. However, the electrocatalytic reaction rate is not only determined by the activity of the catalyst, but also related to the electric field and the properties of the electrolyte itself. 2 The reaction process of S absorption and electrolysis coupling requires, on the one hand, increasing the reaction rate, and on the other hand, strengthening the absorption of hydrogen sulfide.

[0005] Ionic liquids are low-temperature molten salts composed of anions and cations. They have unique physical and chemical properties, such as high ionic conductivity, high electrochemical stability, and a wide electrochemical window. Ionic liquids are designed and developed as electrolytes for the electrochemical conversion of gases. For example, ionic liquids can react with CO 2 In recent years, ionic liquids, especially functionalized ionic liquids, have been widely used in the electrocatalytic reaction of low concentration (low partial pressure) H 2 The functional design of ionic liquids is generally done by grafting H-philic molecules onto anions or cations. 2S functional groups to improve the absorption capacity, such as carboxylate ionic liquids, tertiary amine and hydroxyl double Lewis basic ionic liquids, organic amine / organic acid salt proton type ionic liquids, tertiary amine ionic liquids, benzoic acid ionic liquids, quaternary ammonium salt ionic liquids, iron-based ionic liquids, etc. Chinese patents (CN103159632B, CN113817368A) reported a class of anionic ionic liquids containing double Lewis base functional groups and morpholine basic ionic liquids for removing H 2 S.

[0006] Chinese patent CN111501056A reports an organic electrolyte and a circulating reaction device and process for producing hydrogen by low-temperature electrolysis of hydrogen sulfide. The organic electrolyte includes an ionic liquid, an alcohol amine and an organic solvent, wherein the ionic liquid serves as a supporting electrolyte to improve the ionic conductivity of the organic electrolyte, and the alcohol amine serves to absorb H 2 The effect of S, the solubility of sulfur in the electrolyte is positively correlated with temperature. The dissolution and precipitation of sulfur can be achieved by temperature change to avoid electrode passivation, but the hydrogen yield of the electrolysis system is still low (less than 45 μmol / h); in addition, by adjusting the pH value to acidic, sulfur can be precipitated to achieve the separation of sulfur in the anode alkaline electrolyte; Yu Jiang et al. (Environ. Sci. Technol. 2015, 49, 5697) combined iron-based ionic liquid with DMF to form an anhydrous absorption liquid for absorbing H 2 S is oxidized into sulfur. After the sulfur is separated, the absorption liquid is electrolyzed, and the iron-based ionic liquid is regenerated. At the same time, hydrogen is precipitated at the cathode to form indirect H 2 S electrolytic conversion. However, although the indirect electrolysis method mentioned above can avoid sulfur deposition, it also has disadvantages that cannot be ignored, such as severe corrosion of equipment, high energy consumption, and difficulty in separating sulfur.

[0007] Chinese patent CN202210671327.6 reports an ionic liquid anode electrolyte enhanced hydrogen sulfide absorption-electrolysis coupling technology and its regeneration method, which mainly involves the field of hydrogen sulfide absorption and conversion technology. The invention uses functionalized ionic liquid as both absorption liquid and electrolyte, and uses an electrochemical method to convert H 2 S is decomposed into hydrogen and sulfur, and the pollutant gas H 2 S turns waste into treasure. 2 The efficient absorption of S is coupled with the electrolysis process, and functionalized ionic liquids are used as electrolytes and absorbents to avoid sulfur deposition and increase sulfur yield on the one hand, and to increase hydrogen yield on the other hand, achieving H 2 The process of sulfur absorption and electrolysis is efficiently coupled. At the same time, the separation of sulfur and the regeneration of ionic liquid electrolyte can be achieved through CO 2The absorption and desorption of gases is achieved by passing high-purity CO into the anolyte containing dissolved polysulfides. 2 The sulfur was precipitated by the gas, and then purified sulfur solid was obtained by washing, filtering and drying. Further, nitrogen was introduced into the anolyte from which sulfur was filtered out at a temperature of 40-70°C, with a gas flow rate of 300 mL / min and a ventilation time of 3 h to remove CO 2 The sulfur is desorbed to achieve the regeneration of the anolyte. Although this method solves the problem of sulfur being difficult to separate, the regeneration efficiency of the invention is very low, and it usually takes a long time to complete the regeneration of the electrolyte and the operation is also complicated.

[0008] For H 2 S direct electrolysis method, ionic liquids are rarely used as regulators of traditional electrolytes and as electrolytes and absorbents for H 2 Research on sulfur conversion and resource recovery and separation of sulfur by self-precipitation.

[0009] In view of this, the present invention is proposed. Summary of the invention

[0010] The above electrochemical method directly decomposes H 2 The negative problems of sulfur deposition and low hydrogen yield of S technology are solved. The present invention provides an anolyte for efficient conversion of hydrogen sulfide and its electrolytic regeneration and enhanced sulfur precipitation method, which adopts an electrochemical method to convert H 2 S is decomposed into hydrogen and sulfur, and the pollutant gas H 2 S turns waste into treasure. 2 The efficient absorption of sulfur is coupled with the electrolysis process, and a functionalized ionic liquid + alkaline inorganic solvent system is used as the electrolyte and absorbent. On the one hand, the problem of sulfur being difficult to separate is avoided, and the sulfur yield is increased; on the other hand, the hydrogen yield is increased, and H 2 The processes of S absorption and electrolysis are efficiently coupled.

[0011] In order to solve the above technical problems, the present invention adopts the following technical solutions: An ionic liquid anolyte consists of an ionic liquid and a basic solvent, and the pH value of the anolyte is 12.50-12.8; the ionic liquid is an acetic acid functionalized ionic liquid.

[0012] Furthermore, the base solvent is a NaOH solution with a concentration of 0.5-2 mol / L, and the mass ratio of the ionic liquid to the NaOH solution is 1:19-1:1, preferably 3:7.

[0013] Furthermore, the acetate functionalized ionic liquid is an imidazolyl acetate functionalized ionic liquid, and the imidazolyl acetate functionalized ionic liquid is 1-ethyl-3-methylimidazolyl acetate [Emim] Ac, 1-butyl-3-methylimidazolyl acetate [Bmim] Ac or 1-hexyl-3-methylimidazolyl acetate [Hmim] Ac.

[0014] The present invention also provides the use of the ionic liquid-based anolyte, which is used to strengthen the coupling process of hydrogen sulfide absorption and electrolysis, improve the hydrogen sulfide absorption capacity and hydrogen production rate and strengthen the sulfur precipitation capacity during the electrolysis process, and solve the problem of sulfur passivation on the electrolysis system and the difficulty of sulfur extraction. Specifically, the present invention also provides a method for strengthening sulfur precipitation using the ionic liquid anolyte, comprising the following steps: 2 S is introduced into the anode electrolyte and absorbed until saturated, and constant potential electrolysis is performed to obtain sulfur at the anode and hydrogen at the cathode. During the continuous electrolysis process, sulfur will gradually precipitate at the bottom of the anode electrolyte.

[0015] Furthermore, in the constant potential electrolysis, the method for determining the constant potential is to study the electrochemical behavior of hydrogen sulfide in the anolyte by cyclic voltammetry, and then determine the potential of the constant potential electrolysis.

[0016] Furthermore, when the anolyte absorbs hydrogen sulfide, the specific method is: the gas flow rate is 50-300 mL / min and the concentration is 1000-100000 ppm. 2 S gas is passed through the aeration device into the anode electrolyte until it is absorbed at saturated absorption temperature of room temperature and pressure of normal pressure; the constant potential electrolysis voltage is 1.2 V vs. RHE, the constant potential electrolysis time is 12 h, and slow magnetic stirring is applied during the electrolysis process to make the anode liquid components more uniform. The reaction temperature of the electrolysis process is room temperature and the pressure is normal pressure.

[0017] Furthermore, the catholyte used in the constant potential electrolysis is 0.5-1.0 mol / LH 2 SO 4 Aqueous solution, preferably 0.5 mol / LH 2 SO 4 Aqueous solution.

[0018] Furthermore, after the electrolysis reaction is completed, the electrolyte is allowed to stand for 1 hour, and after the sulfur is precipitated, the sulfur is separated from the electrolyte by filtration. After separation, NaOH is added thereto to achieve regeneration of the anode electrolyte.

[0019] Furthermore, sulfur is a self-precipitation process, so only one filtration process is required during extraction, and no other operations are required. Only after solid-liquid separation, NaOH is added to the electrolyte. The above steps can achieve regeneration of the anolyte.

[0020] Furthermore, the catholyte used in the constant potential electrolysis is 0.5-1.0 mol / LH 2 SO 4 Aqueous solution, The beneficial effect of the present invention is: screening with high H 2 Functionalized ionic liquids with S absorption performance groups use functionalized ionic liquids and inorganic solvent systems as absorption liquids and electrolytes at the same time. On the one hand, they can efficiently absorb hydrogen sulfide, and on the other hand, they can couple the hydrogen sulfide electrolysis process. (1) During the absorption of rich liquid electrolysis, the sulfur generated at the anode gradually precipitates at the bottom of the anode electrolyte and can be extracted by filtration. (2) H 2 The solubility of S in the electrolyte increases significantly. 2 The bonding effect of S effectively promotes the electrolysis reaction, greatly improving the cathode hydrogen production rate and sulfur precipitation rate, which is better than most systems using electrocatalysts and effectively reduces the cost of electrolysis.

[0021] Compared with the prior art, the maximum hydrogen production rate of the present invention reaches 3945.9 μmol·h -1 Moreover, the sulfur separation method is more convenient and energy-efficient, and does not require additional operations or the use of resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1 It is a structural schematic diagram of the hydrogen sulfide absorption-electrolysis system provided by the present invention.

[0024] A.H 2 S gas cylinder; B, N 2 Gas cylinder; C and D, gas mass flow meter; E, electrochemical workstation; F, H type electrolytic cell; G, gas chromatograph; H, H 2 S analyzer; I. ​​Tail gas absorption device.

[0025] Figure 2 Different electrolysis systems (10wt% [Emim] Ac + NaOH; 10wt% [Bmim] Ac + NaOH; 10wt% [Hmim] Ac + NaOH; 10wt% [BDMAEE] Ac + NaOH; 1mol L -1 NaOH) in H 2LSV plot of S-saturated electrolyte.

[0026] Figure 3 The results are as follows: different electrolysis systems (5wt% [Hmim] Ac + NaOH; 10wt% [Hmim] Ac + NaOH; 20wt% [Hmim] Ac + NaOH; 30wt% [Hmim] Ac + NaOH; 50wt% [Hmim] Ac + NaOH) in H 2 LSV plot of S-saturated electrolyte.

[0027] Figure 4 Different electrolyte systems (10wt% [Emim] Ac + NaOH; 10wt% [Bmim] Ac + NaOH; 10wt% [Hmim] Ac + NaOH; 10wt% [BDMAEE] Ac + NaOH; 1mol L -1 The hydrogen production rate curve of NaOH at 1.2 V constant potential electrolysis for 12 h.

[0028] Figure 5 This is a curve of hydrogen production rate after 12 h of constant potential electrolysis at 1.2 V for different electrolyte systems (5wt% [Hmim]Ac+NaOH; 10wt% [Hmim]Ac+NaOH; 20wt% [Hmim]Ac+NaOH; 30wt% [Hmim]Ac+NaOH; 50wt% [Hmim]Ac+NaOH).

[0029] Figure 6 XRD spectrum of the solid product separated from the anolyte after 12 h of electrolysis.

[0030] Figure 7 It absorbs H 2 Mass spectra of electrolyte before and after S.

[0031] Figure 8 It absorbs H 2 H NMR spectra of the electrolyte before and after S.

[0032] Fig. 9 This is a diagram of sulfur precipitation in the electrolyte. DETAILED DESCRIPTION

[0033] The present invention is further described below in conjunction with the accompanying drawings and embodiments, but the present invention is not limited to the following embodiments. Without departing from the scope of the purpose described in the claims, all changes and implementations are included in the technical scope of the present invention.

[0034] Example 1 The preparation method of the ionic liquid anolyte of this embodiment is as follows: Take [Hmim]Ac as an example: First, soak the anion exchange resin in deionized water for 48 hours, then pour out the excess water to remove impurities; then soak it in a 2 mol·L¹ NaOH solution prepared in advance for 48 hours. Then pour the treated resin into an ion exchange column with a column length of 100 cm and an inner diameter of 6 cm. Be careful not to bring air into the column during the pouring process. Then rinse the ion exchange resin with sodium hydroxide solution (2 mol·L, flow rate of 10 mL·min), and rinse with AgNO 3 -HNO 3 Mix the solution and test (until no halide ions are detected. 3 -HNO 3 When no halide ions are detected in the mixed solution, it means that the column has been flushed and the resin has finally converted from halide type to OH type.

[0035] Rinse the column with deionized water until it is neutral, drain the water from the resin, dilute [Hmim]Br with an equal volume of deionized water, and then pour it into the column for exchange. At the same time, place a 100 ml beaker below to receive it. Note that pH test paper and AgNO should be used during the collection process. 3 -HNO 3 The mixed solution is tested, and the liquid can only be collected when it is alkaline. The collection is completed when a light yellow precipitate appears in the liquid. Then the collected liquid is sealed and stored. At this time, the colorless transparent liquid is [Hmim]OH alkaline ionic liquid. First, the prepared [Hmim]OH alkaline solution is accurately titrated with hydrochloric acid of known concentration. In order to determine the molar concentration of [Hmim]OH, acetic acid is added dropwise with a slightly excess molar ratio, and magnetic stirring is performed under an ice water bath. After 48 hours of reaction, the obtained [Hmim]Ac is rotary evaporated, and vacuum dried for 48 hours to obtain a colorless [Hmim]Ac alkaline functional ionic liquid. The [Hmim]Ac alkaline functional ionic liquid and the NaOH solution with a concentration of 1 mol·L¹ are prepared in a mass ratio of 3:7 to 50 mL, stirred evenly and ultrasonicated for 30 min, which is the prepared ionic liquid anode electrolyte.

[0036] The electrolysis process of this embodiment is as follows: H is introduced into the prepared ionic liquid anolyte. 2 S gas, H 2 The S concentration was 10000 ppm, the ventilation flow rate was 100 mL / min, and the ventilation time was 16h-18h, so that the anode liquid reached absorption saturation. 2S uses an H-type electrolytic cell, separated by a Nafion 117 proton exchange membrane in the middle, and constant potential electrolysis is performed on an electrochemical workstation. In this three-electrode system, a carbon cloth (1cm×1cm) electrode is used as the working electrode, a Hg / HgO electrode is used as the reference electrode, and the cathode liquid is 50 mL0.5mol / L sulfuric acid solution. The constant potential electrolysis voltage is 1.2 V vs. RHE, the electrolysis time is 12 h, slow magnetic stirring is applied during the electrolysis process, the reaction temperature is room temperature, and the pressure is normal pressure. The hydrogen generated at the cathode is detected by a hydrogen analyzer to detect the concentration and calculate the hydrogen production rate. The maximum hydrogen production rate of this embodiment is 3945.9μmol / h, high-purity sulfur is obtained, and the sulfur recovery rate is 82.6%.

[0037] like Figure 1 As shown, the device used in the efficient decomposition process of hydrogen sulfide includes: Gas circuit device: H 2 S / N 2 Gas cylinders and gas mass flow meters; O 2 Gas cylinders and gas mass flow meters.

[0038] Electrochemical device: H-type electrolytic cell and electrochemical workstation. Among them, the H-type electrolytic cell consists of a cathode chamber, an anode chamber, an electrolyte and a proton exchange membrane. Preferably, the proton exchange membrane model is Nafion117. The present invention adopts a three-electrode system, which is divided into an anode cell, a cathode cell and a proton exchange membrane. The working electrode is a carbon cloth (1 cm×1 cm) fixed by a platinum electrode clamp, the reference electrode is Hg / HgO or Ag / AgCl, and the counter electrode is a platinum sheet or graphite, preferably a platinum sheet, and no synthetic catalyst is added.

[0039] Detection device: Gas chromatograph is used to detect cathode hydrogen, H 2 S analyzer for H 2 S concentration detection.

[0040] Tail gas absorption device: for H 2 S exhaust absorption.

[0041] Example 2 The preparation method of the anolyte in this embodiment refers to Experimental Example 1. The preparation method of the anolyte is to prepare 50 mL of [Bmim]Ac and a 1 mol·L¹ NaOH solution in a mass ratio of 1:9, stir evenly, and then perform ultrasound for 30 minutes to obtain the prepared anolyte.

[0042] The electrolysis process of this embodiment is as follows: H was introduced into the anolyte 2 S gas, H 2The S concentration was 10000 ppm, the ventilation flow rate was 100 mL / min, and the ventilation time was 16h-18h, so that the anode liquid reached absorption saturation. 2 S uses an H-type electrolytic cell, separated by a Nafion 117 proton exchange membrane in the middle, and constant potential electrolysis is performed on an electrochemical workstation. In this three-electrode system, a carbon cloth electrode is used as the working electrode, a Hg / HgO electrode is used as the reference electrode, and the cathode liquid is 50mL of a 0.5mol / L sulfuric acid solution. The constant potential electrolysis voltage is 1.2 V (vs. RHE), the electrolysis time is 12 h, slow magnetic stirring is applied during the electrolysis process, the reaction temperature is room temperature, and the pressure is normal pressure. The hydrogen produced at the cathode is detected by a gas chromatograph to detect the concentration and calculate the hydrogen production rate. The maximum hydrogen production rate of this embodiment is 511.1 μmol / h, high-purity sulfur is obtained, and the sulfur recovery rate is 47.5%.

[0043] Example 3 The ionic liquid synthesis method of this embodiment refers to Experimental Example 1. The preparation method of the anolyte is to prepare 50 mL of [Emim]Ac and 1 mol·L¹ NaOH solution in a mass ratio of 1:9, stir evenly and then ultrasonicate for 30 min to obtain the prepared anolyte.

[0044] The electrolysis process of this embodiment is as follows: H was introduced into the anolyte 2 S gas, H 2 The S concentration was 10000 ppm, the ventilation flow rate was 100 mL / min, and the ventilation time was 18 h, so that the anode liquid reached absorption saturation. 2 S uses an H-type electrolytic cell, separated by a Nafion 117 proton exchange membrane in the middle, and constant potential electrolysis is performed on an electrochemical workstation. In this three-electrode system, a carbon cloth electrode is used as the working electrode, a Hg / HgO electrode is used as the reference electrode, and the cathode liquid is 50 mL of 0.5 mol / L sulfuric acid solution. The constant potential electrolysis voltage is 1.2 V (vs. RHE), the electrolysis time is 12 h, slow magnetic stirring is applied during the electrolysis process, the reaction temperature is room temperature, and the pressure is normal pressure. The hydrogen generated at the cathode is detected by a hydrogen analyzer to detect the concentration and calculate the hydrogen production rate. The maximum hydrogen production rate of this embodiment is 441.1 μmol / h, and high-purity sulfur is obtained, and the sulfur recovery rate is 41.4%.

[0045] Figure 1 The structure diagram of the hydrogen sulfide absorption-electrolysis system provided by the present invention is as follows: when the anode electrolyte absorbs hydrogen sulfide, the specific method is: the gas flow rate is 50-300 mL / min, the concentration is 1000-100000 ppm of H 2S gas is introduced into the anolyte through an aeration device until it is absorbed saturated. Preferably, the balance gas is nitrogen, H 2 The flow rate of S mixed gas was 100 mL / min, and H 2 The S concentration is 10000 ppm, the ventilation time is 15-19 hours, the reaction temperature of the absorption and electrolysis process is room temperature, and the pressure is normal pressure.

[0046] 1. Effect of different anolytes on H 2 Absorption performance of S The effects of different anolytes on H 2 Absorption properties of S.H 2 The S gas flow rate was 100 mL / min, and the H 2 The S gas concentration is 10000 ppm, and the anolyte is divided into 7 types according to the type and component concentration: 10wt% [Emim]Ac+NaOH solution, 10wt% [Bmim]Ac+NaOH solution, 5wt% [Hmim]Ac+NaOH solution, 10wt% [Hmim]Ac+NaOH solution, 20wt% [Hmim]Ac+NaOH solution, 30wt% [Hmim]Ac+NaOH solution and 50wt% [Hmim]Ac+NaOH solution. The overall absorption of H by different electrolyte systems 2 The S capacity is 10wt% [Hmim]Ac + NaOH solution> 30wt% [Hmim]Ac + NaOH solution> 10wt% [Emim]Ac + NaOH solution> 10wt% [Bmim]Ac + NaOH solution> 5wt% [Hmim]Ac + NaOH solution> 20wt% [Hmim]Ac + NaOH solution> 50wt% [Hmim]Ac + NaOH solution. And the absorption of H by the three electrolytes of 10wt% [Emim]Ac + NaOH solution, 10wt% [Hmim]Ac + NaOH solution and 30wt% [Hmim]Ac + NaOH solution is 2 S has the best performance and can achieve 100% absorption in 17 hours. The above-mentioned NaOH solutions all use a concentration of 1 mol·L¹. Table 1 shows the hydrogen yield of different electrolyte systems.

[0047] Table 1 Hydrogen yield of different electrolyte systems 2. Screening of basic solvents in electrolyte [Hmim]Ac ionic liquid was selected to screen the basic solvents (water, NaOH with a concentration of 1 mol·L¹, DMF and TGDE) in the composite electrolyte, and the results are listed in Table 1. The temperature was 20 oC, the amount of [Hmim]Ac ionic liquid added was 30 wt%, and the applied voltage was 0.9 V vs. RHE. 2 S, the hydrogen production rate is relatively high, reaching 3945.9 μmol / h.

[0048] Table 2 Hydrogen production rate of the coupled system of [Hmim]Ac ionic liquid and composite anolyte with different basic solvents 3. Electrochemical performance test of different electrolysis systems (LSV curve) Figure 2 , Figure 3 The LSV curves of different electrolytic systems are described. The experiment uses carbon cloth as anode and platinum sheet as cathode. The absorption-electrolysis H of ionic liquid + NaOH solution system is tested by three-electrode system. 2 The electrochemical properties of S were investigated and three alkaline ionic liquids were screened out, namely [Emim]Ac, [Bmim]Ac, and [Hmim]Ac. The anode SOR reaction (0.24-0.6 V) of each system has a lower voltage than the OER reaction (1.8 V), indicating that the SOR process is more thermodynamically favorable in these systems. 2 The SOR reaction at the S system anode has a lower voltage of 0.24 V.

[0049] 4. Electrolysis of H in different electrolyte systems 2 S hydrogen production rate determination Figure 4 , Figure 5 The graph shows the hydrogen production rate curves of different electrolyte systems for 12 h of electrolysis. The applied voltage is 1.2 V vs. RHE. The hydrogen production rate for 12 h of electrolysis is 441.1-3945.9 μmol·h -1 The system with the highest hydrogen production rate is 30wt% [Hmim]Ac+NaOH solution / H 2 S, the highest can reach 3945.9 μmol·h -1 .

[0050] 5. Electrolysis of H in different electrolyte systems 2 S anode product determination Figure 6 The XRD spectrum and photos of the electrolytic anode product are described. The solid product is obtained by filtering the electrolyte for 1 hour. The solid product is characterized by XRD and is α-sulfur. 2 S, absorb H 2After S saturation and SOR reaction for 12 hours, the color depth of the electrolyte is related to the amount of sulfur oxidation products dissolved. The greater the amount dissolved, the darker the color.

[0051] The carbon cloth was used as the anode, the platinum sheet was used as the cathode, the anolyte was composed of different ionic liquids and water, and the catholyte was 0.5 mol / LH 2 SO 4 Solution; Absorption and electrolysis temperature: room temperature; H of seven systems 2 The S absorption performance, electrochemical performance and hydrogen production rate are listed in Table 2.

[0052] Table 3 H of seven systems 2 S absorption performance, electrochemical performance and hydrogen production rate 6. Characterization and determination of properties of ionic liquids before and after absorption and electrolysis Figure 7 , Figure 8 This paper describes the characterization of the properties of ionic liquids before and after absorption-electrolysis. Through liquid chromatography-mass spectrometry and nuclear magnetic resonance hydrogen spectrum characterization, the structural state of the ionic liquid before and after the reaction was explored. Through comparative analysis, the structural state of the ionic liquid before and after the reaction did not change, and the same characteristic peaks existed, indicating that the ionic liquid structure has a certain stability, can maintain its own structural integrity after absorption electrolysis, and has the potential for recycling.

[0053] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. An ionic liquid anolyte, characterized in that: The anode electrolyte consists of an ionic liquid and a basic solvent, and the pH value of the anode electrolyte is 12.50-12.8; the ionic liquid is an acetic acid functionalized ionic liquid.

2. The ionic liquid anolyte according to claim 1, characterized in that: The base solvent is a NaOH solution with a concentration of 0.5-2 mol / L, and the mass ratio of the ionic liquid to the NaOH solution is 1:19-1:

1.

3. The ionic liquid anolyte according to claim 2, characterized in that: The acetic acid functionalized ionic liquid is an imidazolyl acetic acid functionalized ionic liquid, and the imidazolyl acetic acid functionalized ionic liquid is 1-ethyl-3-methylimidazolyl acetate [Emim] Ac, 1-butyl-3-methylimidazolyl acetate [Bmim] Ac or 1-hexyl-3-methylimidazolyl acetate [Hmim] Ac.

4. A method for enhancing sulfur precipitation using the ionic liquid anolyte according to any one of claims 1 to 3, characterized in that The following steps are involved: H2S is introduced into the anode electrolyte and absorbed until saturated, and constant potential electrolysis is performed to obtain sulfur at the anode and hydrogen at the cathode. During the continuous electrolysis process, sulfur will gradually precipitate at the bottom of the anode electrolyte.

5. The method for enhancing sulfur precipitation using an ionic liquid anolyte according to claim 4, characterized in that: When the anolyte absorbs hydrogen sulfide, the specific method is: H2S gas with a gas flow rate of 50-300 mL / min and a concentration of 1000-200000 ppm is passed through the aeration device into the anolyte until absorption is saturated; the absorption reaction temperature is room temperature and the pressure is normal pressure.

6. The method for enhancing sulfur precipitation using an ionic liquid anolyte according to claim 4, characterized in that: The working electrode of the constant potential electrolysis was a carbon cloth fixed by a platinum electrode clamp, the reference electrode was Hg / HgO or Ag / AgCl, the counter electrode was a platinum sheet or graphite, no synthetic catalyst was added, the constant potential electrolysis voltage was 1.2 V, and the constant potential electrolysis time was 12 h.

7. The method for enhancing sulfur precipitation using an ionic liquid anolyte according to claim 4, characterized in that: During the constant potential electrolysis process, slow magnetic stirring is applied on both sides simultaneously to make the components of the anode liquid more uniform and to prevent the cathode hydrogen from adhering to the surface of the counter electrode and causing a decrease in the reaction rate. The reaction temperature of the electrolysis process is room temperature and the pressure is normal pressure.

8. The method for enhancing sulfur precipitation using an ionic liquid anolyte according to claim 4, characterized in that: The cathode electrolyte used in constant potential electrolysis is 0.5-1.0 mol / L H2SO4 aqueous solution.

9. The method for enhancing sulfur precipitation using an ionic liquid anolyte according to claim 4, characterized in that: After the electrolysis reaction is completed, the electrolyte is allowed to stand for 1 hour. After the sulfur is precipitated, the sulfur is separated from the electrolyte by filtration. After separation, NaOH is added to the electrolyte to achieve regeneration of the anode electrolyte.

10. The method for enhancing sulfur precipitation using an ionic liquid anolyte according to claim 9, characterized in that: Sulfur is a self-precipitation process, so only one filtration process is required during extraction, and no other operations are required. Only after solid-liquid separation, NaOH is added to the electrolyte. The above steps can achieve regeneration of the anode electrolyte.

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