Preparation method and application of guanidine salt conjugated polyacid functionalized eutectic solvent liquid-phase desulfurizer

Abstract

The invention discloses a preparation method and application of a guanidine salt conjugated polyacid functionalized eutectic solvent liquid-phase desulfurizer, and belongs to the technical field of gas purification, and the liquid-phase desulfurizer mainly utilizes the buffer blending capability of a eutectic solvent to simultaneously bear tetramethylguanidine and polyoxometallate to form an acid-base conjugated system; the desulfurization performance of the liquid-phase desulfurizer is enhanced by the guanidine salt alkaline groups and the metal active sites of the polyoxometallate together. The desulfurization performance of the guanidine salt conjugated polyacid functionalized deep-eutectic solvent is enhanced by adopting electrochemical treatment, and the desulfurization performance of a guanidine salt conjugated polyacid functionalized deep-eutectic solvent system is greatly enhanced after electrochemical treatment. The liquid-phase desulfurizing agent disclosed by the invention is simple to synthesize and stable in performance, is convenient to operate a hydrogen sulfide removal process, has extremely excellent desulfurizing performance, and has important significance on developing an industrial liquid-phase desulfurizing agent which is efficient, low in cost and easy to operate.

Description

Technical Field

[0001] The present invention relates to the technical field of gas purification, and in particular to a preparation method and application of a novel guanidine salt conjugated polyacid functionalized deep eutectic solvent liquid phase desulfurizer. Background Art

[0002] Hydrogen sulfide (H2S), a toxic gas with a strong rotten-egg odor, is widely present in various industrial processes, such as petroleum refining, natural gas processing, chemical production, bioenergy production, and wastewater treatment. Hydrogen sulfide not only causes serious environmental pollution but is also highly corrosive, damaging equipment and pipelines and increasing maintenance costs. Furthermore, H2S poses significant health risks. Low-concentration exposure can cause respiratory irritation and headaches, while high-concentration exposure can lead to coma or even death. Therefore, the efficient removal of H2S gas is a critical task in both industrial production and environmental protection.

[0003] Currently, commonly used hydrogen sulfide removal technologies in industry include physical absorption, chemical absorption, and biological desulfurization. Hydrogen sulfide is adsorbed by physical adsorbents (such as activated carbon and molecular sieves). Although this method is simple to operate, the adsorbent has limited adsorption capacity, a complex regeneration process, and high costs. Chemical absorbents (such as amine compounds and alkaline solutions) react with hydrogen sulfide to form stable compounds. This method has high absorption efficiency, but the absorbent stability is not ideal, causing corrosion to equipment and potential secondary pollution. In recent years, deep eutectic solvents (DESs) have attracted widespread attention in the field of gas desulfurization as a new type of green solvent. Deep eutectic solvents are liquids formed by mixing two or more components, hydrogen bond acceptors (HBAs) and hydrogen bond donors (HBDs), in a specific ratio. They exhibit low volatility, high thermal stability, and good solubility. These properties make deep eutectic solvents significantly advantageous in gas absorption processes, but their absorption efficiency remains to be improved in the treatment of high-concentration industrial gases.

[0004] Existing deep eutectic solvent absorbents have weak absorption properties. Further improving the absorption capacity and selectivity of deep eutectic solvents for acidic gases through functionalization has become a research hotspot. However, relatively little research has been conducted in the field of gas desulfurization. To address this, we functionalized the deep eutectic solvent with acid-base conjugates using polyoxometalates and tetramethylguanidine, and enhanced its desulfurization performance through electrochemistry, providing an innovative and highly effective technical solution for the efficient removal of H2S gas. Summary of the Invention

[0005] The purpose of the invention is to provide a non-aqueous solvent desulfurizer with a simple preparation method, low cost, high stability, and excellent desulfurization performance to address the practical application challenges faced by conventional deep eutectic solvent desulfurizers. A functionalized deep eutectic solvent prepared by combining an acid-base conjugate system of polyoxometalates and tetramethylguanidine in a deep eutectic solvent buffer solution exhibits excellent desulfurization performance. Furthermore, electrochemically enhanced desulfurization performance can be significantly enhanced, while leveraging the advantageous properties of polyoxometalates, tetramethylguanidine, and the deep eutectic solvent.

[0006] Technical solution: A method for preparing a new type of guanidine salt conjugated polyacid functionalized deep eutectic solvent liquid phase desulfurizer, such as Figure 1 As shown, the process involves combining choline chloride with various hydrogen bond donors in varying proportions to prepare various deep eutectic solvents, combining them with tetramethylguanidine salt to prepare a functionalized deep eutectic solvent, adding polyoxometalates to prepare a guanidine conjugated polyacid functionalized deep eutectic solvent as a liquid-phase desulfurization agent, and then electrochemically enhancing the desulfurization performance of the guanidine conjugated polyacid functionalized deep eutectic solvent. Hydrogen sulfide is removed using a gas-liquid absorption reaction device, and regeneration is achieved by heated air stripping and electrochemical regeneration.

[0007] The deep eutectic solvent is mainly a choline-based deep eutectic solvent, which is prepared by combining hydrogen bond donors such as ethylene glycol, glycerol, and urea with choline chloride in a molar ratio of 1:1 to 1:3 and then heating and stirring.

[0008] The functionalized low eutectic solvent is mainly prepared by adding 1-10% of 1,1,3,3-tetramethylguanidine to the low eutectic solvent.

[0009] The guanidine salt conjugated polyacid functionalized deep eutectic solvent liquid phase desulfurizer is mainly prepared by adding 0.025-0.02 mol / L of phosphomolybdate to the functionalized deep eutectic solvent and stirring and dissolving the mixture.

[0010] The electrochemical strengthening method mainly comprises placing a guanidine salt conjugated polyacid functionalized deep eutectic solvent liquid phase desulfurizer into an electrochemical strengthening device, controlling the current to be 0.01A, and the electrochemical strengthening time is mainly 2-24 hours.

[0011] The electrochemical enhancement device mainly consists of a DC power supply and an H-type electrochemical cell. A guanidine salt conjugated polyacid functionalized deep eutectic solvent solution is placed in the cathode chamber, and the anode chamber is a 0.1 mol / L potassium bicarbonate aqueous solution, which is separated by a proton exchange membrane. The electrode uses carbon paper with a size of 2 cm × 5 cm.

[0012] The gas-liquid absorption reaction device is mainly used to remove hydrogen sulfide by adding 5ml of guanidine salt conjugated polyacid functionalized deep eutectic solvent to the bubbling gas absorption bottle, controlling the absorption temperature to 25℃-75℃, and introducing hydrogen sulfide-containing gas with a flow rate of 200mL / min and a concentration of 500-2000mg / m3 .

[0013] The regeneration method mainly includes controlling the regeneration temperature to 75°C, introducing an air bubbling regeneration flow rate of 200 mL / min, and the regeneration time to 4-6 hours. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 Schematic diagram of the preparation and application process of guanidine salt conjugated polyacid functionalized deep eutectic solvent

[0015] Figure 2 The desulfurization performance of different components of the guanidine salt conjugated polyacid functionalized deep eutectic solvent before and after electrochemical treatment at 75°C is shown.

[0016] Figure 3 The desulfurization regeneration performance of the guanidine salt conjugated polyacid functionalized deep eutectic solvent before and after electrochemical treatment at 75 ° C

[0017] Figure 4 Desulfurization performance of comparative examples 1 and 2 of the present invention

[0018] The desulfurization principle of the present invention is:

[0019] The deep eutectic solvent first forms hydrogen bonds with tetramethylguanidine, forming a buffer layer around the guanidine salt. When polyoxometalates are added to the system, the buffer layer formed by the deep eutectic solvent prevents the strong acid-base neutralization reaction between the polyoxometalates and tetramethylguanidine, allowing the two to form a stable acid-base conjugate system in the deep eutectic solvent. Once the conjugate system is formed, the guanidine salt and polyoxometalates, while maintaining their structural integrity, significantly enhance the deep eutectic solvent's ability to capture hydrogen sulfide through the guanidine salt's basic groups and the polyoxometalates' metal sites, respectively. During the electrochemical process, water contained in the deep eutectic solvent is reduced to OH- at the cathode, which combines with choline cations to form choline hydroxide, significantly enhancing desulfurization performance. As an excellent solvent, the deep eutectic solvent not only provides the conditions for the acid-base conjugate system through its unique buffering effect, but also emerges as a key desulfurization component after electrochemical treatment. The synergistic mechanism of these three factors enables the guanidine salt-conjugated polyoxometalates-functionalized deep eutectic solvent to exhibit excellent desulfurization performance as a liquid-phase desulfurizer.

[0020] The beneficial effect of the present invention is that it combines acid and base substances into a stable liquid phase desulfurizer and combines it with electrochemical enhancement for gas purification and resource application research. The synthesis method of the new guanidine salt conjugated polyacid functionalized deep eutectic solvent is simple and has excellent desulfurization effect, such as Figure 2As shown, the optimal desulfurizer, TPDES, can maintain 100% desulfurization efficiency for 180 minutes and steadily improves with increasing temperature. In particular, after electrochemical treatment, the optimal desulfurizer, ETPDES, can maintain 100% desulfurization efficiency for nearly 10 hours. This overcomes the weak desulfurization performance of conventional deep eutectic solvents and provides an efficient, economical, and environmentally friendly solution for industrial gas purification using functionalized deep eutectic solvents. Furthermore, the structural tunability of deep eutectic solvents is fully utilized, providing theoretical guidance for the rational design and controllable construction of acid-base conjugate systems. DETAILED DESCRIPTION

[0021] The present invention will be further described below with reference to the following examples and comparative examples, but the protection scope of the present invention is not limited to the examples.

[0022] Example 1 Preparation method of a novel guanidine salt conjugated polyacid functionalized deep eutectic solvent liquid phase desulfurization agent

[0023] (1) Preparation method of functionalized deep eutectic solvent liquid phase desulfurizer

[0024] Choline chloride (ChCl) was mixed with hydrogen bond donors (HBD) (ethylene glycol (EG), urea (Urea), and glycerol (Gly)) in a molar ratio of 1:1-1:3. The mixture was heated at 80°C with stirring for 4 hours until a clear, homogeneous liquid was obtained. The prepared choline-based deep eutectic solvents were labeled xGly / ChCl, xEG / ChCl, and xUrea / ChCl, where x is the molar ratio of HBD to ChCl. Tetramethylguanidine (TMG) was added to the DESs at a mass ratio of 1%-10% and stirred at room temperature for 4 hours. The mixture was labeled TDES@n%, where n is the mass ratio of TMG added.

[0025] (II) Preparation method of 0.01 mol / L guanidine salt conjugated polyacid functionalized deep eutectic solvent liquid phase desulfurizer

[0026] Weigh 0.09 g (0.05 mmol) of phosphomolybdic acid (H3PMo 12 O 40 ·13H2O) was dissolved in TDES and stirred at room temperature to obtain a light blue clear solution, which was then heated and stirred at 70°C for 2 h to obtain a clear transparent solution. The obtained guanidine salt conjugated polyacid functionalized deep eutectic solvent was labeled TPDES@n%, where n is the mass ratio of TMG added.

[0027] (III) Electrochemically enhanced treatment method of 0.01 mol / L guanidine salt conjugated polyacid functionalized deep eutectic solvent liquid phase desulfurization agent

[0028] 15 ml of 0.01 mol / L TPDES@n% was weighed and added to the cathode chamber of an H-type electrolytic cell, and an equal volume of 0.1 mol / L potassium bicarbonate solution was added to the anode chamber. A current of 0.01 A was applied to both sides through a DC power supply at room temperature. The electrochemical treatment time was 2-24 h. The guanidine conjugated polyacid functionalized low eutectic solvent after electrochemical treatment was recorded as EyTPDES, where y is the electrochemical treatment time.

[0029] Example 2 Application of desulfurization technology of functionalized deep eutectic solvent liquid phase desulfurizer

[0030] TDES@5% was prepared by adding 5% TMG to 2EG / ChCl. 5 ml TDES was placed in a gas-liquid absorption reactor and the concentration was 1000 mg / mL. 3 The desulfurization experiment of H2S gas was carried out, the absorption temperature was controlled at 75℃, and the concentration of hydrogen sulfide in the tail gas was detected. Under the above conditions, the desulfurization efficiency of TDES@5% remained at 100% within 150 minutes. Figure 2 shown.

[0031] Example 30.01 mol / L Guanidine Salt Conjugated Polyacid Functionalized Deep Eutectic Solvent Liquid Phase Desulfurization Agent Desulfurization Technology Application

[0032] TDES@5% was prepared by adding 5% TMG to 2EG / ChCl, and TPDES@5% was prepared by adding 0.01mol / L phosphomolybdic acid. 5ml TPDES was placed in a gas-liquid absorption reactor and the concentration was 1000mg / m 3 The desulfurization experiment of H2S gas was carried out, the absorption temperature was controlled at 75℃, and the concentration of hydrogen sulfide in the tail gas was detected. Under the above conditions, the desulfurization efficiency of TPDES@5% was maintained at 100% within 180 minutes. Figure 2 shown.

[0033] Example 40.01 mol / L Electrochemically Treated Guanidine Salt Conjugated Polyacid Functionalized Deep Eutectic Solvent Liquid Phase Desulfurization Agent Desulfurization Technology Application

[0034] TDES@5% was prepared by adding 5% TMG to 2EG / ChCl, TPDES@5% was prepared by adding 0.01 mol / L phosphomolybdic acid, and E was prepared by electrochemical treatment in an electrochemical treatment device for 24 h. 24h TPDES, take 5ml E 24h TPDES was placed in a gas-liquid absorption reactor and the concentration was 1000 mg / m 3 The desulfurization experiment of H2S gas was carried out, the absorption temperature was controlled at 75℃, and the concentration of hydrogen sulfide in the tail gas was detected. 24h The desulfurization efficiency of TPDES@5% remained at 100% within 570 minutes. Figure 2 shown.

[0035] Example 50.01 mol / L Guanidine Conjugated Polyacid Functionalized Deep Eutectic Solvent Liquid Phase Desulfurization Agent Regeneration Application

[0036] The desulfurized guanidine salt conjugated polyacid functionalized deep eutectic solvent TPDES@5% was regenerated by bubbling air at 200 mL / min at 75°C. After regeneration, the desulfurization performance of TPDES@5% was restored, and the desulfurization efficiency was maintained at 100% within 80 minutes. Figure 3 shown.

[0037] Example 6 Regeneration of 0.01 mol / L Electrochemically Treated Guanidine Conjugated Polyacid Functionalized Deep Eutectic Solvent Liquid Phase Desulfurization Agent

[0038] The desulfurized electrochemically treated guanidine salt conjugated polyacid was functionalized into a deep eutectic solvent E 24h TPDES@5% was bubbled with air at 200 mL / min at 75°C for 24 hours, and then placed in an electrochemical treatment device for 24 hours to complete the regeneration. 24h The desulfurization performance of TPDES@5% can be restored and the desulfurization efficiency can be maintained at 100% within 500 minutes. Figure 3 shown.

[0039] Comparative Example 1: Application of Desulfurization Technology in the Preparation of 0.01 mol / L Polyacid Functionalized Deep Eutectic Solvent by Adding Polyethyleneimine

[0040] Comparative Example 1 Compared with Example 3, in the preparation process of the functionalized deep eutectic solvent, 5% of polyethyleneimine PEI was added instead, and other conditions remained unchanged. When polyethyleneimine was added to prepare the polyacid functionalized deep eutectic solvent under the above conditions, the desulfurization efficiency was only maintained at 80% within 80 minutes. Figure 4 The desulfurization performance is much lower than that of Example 3 in the present invention.

[0041] Comparative Example 2 Application of desulfurization technology of guanidine salt conjugated polyacid functionalized deep eutectic solvent prepared by adding only ethylene glycol as solvent after electrochemical treatment

[0042] Comparative Example 2 Compared with Example 4, in the preparation process of the functionalized deep eutectic solvent in Comparative Example 2, ethylene glycol was used as the solvent instead of DES, and other conditions remained unchanged. 24h TPDES@5% can only maintain 100% desulfurization performance for 120 minutes. Figure 4 The desulfurization performance is much lower than that of Example 4 in the present invention.

[0043] Comparative Example 3: Aminocyclophosphazene functionalized polyacid non-aqueous solvent

[0044] This comparative example utilizes PPILs@IBuPN-9, disclosed in Chinese invention patent application number 202410724153.4 and publication number CN 118454415 A. The PPILs@IBuPN-9 was prepared by combining isobutylaminocyclophosphazene with phosphomolybdic acid in a 3:1 molar ratio and adding it to 1-butyl-3-methylimidazole chloride. As shown in Table 1, the desulfurization performance at 100°C was only maintained at 99% for 120 minutes, which is lower than that of Examples 3 and 4 of the present invention.

[0045] Table 1 is a comparison of the desulfurization performance of the liquid phase desulfurizer of the present invention and different non-aqueous liquid phase desulfurization systems

[0046] Desulfurizer Type Penetration time Applicable temperature window Desulfurization efficiency TPDES@5% 180 minutes 25-75℃ 100％ <![CDATA[E 24h TPDES@5%]]> 570 minutes 25-75℃ 100％ PPILs@IBuPN-9 120 minutes 100℃-200℃ 99％ 0.5Cu-DES-NFs 80 minutes 25℃ 100％

[0047] Comparative Example 4 Application of deep eutectic solvent-nano copper type nanofluid non-aqueous liquid phase desulfurization technology

[0048] In this comparative experiment, reference was made to the preparation method of 0.5Cu-DES-NFs disclosed in the Chinese invention patent with patent application number 202010802965.8 and publication number CN111888891A. Ethanolamine with a mass ratio of 20% was added to 2EG / ChCl, and the mixture was evenly mixed by bubbling to prepare a functionalized low eutectic solvent. Then, nano-copper powder with a mass ratio of 0.5% was weighed and added to the above-mentioned low eutectic solvent. After 30 minutes of magnetic stirring and 1 hour of intermittent ultrasonic treatment, 0.5Cu-DES-NFs was finally obtained. As shown in Table 1, at 25°C, the comparative sample can only maintain a desulfurization efficiency of 100% within 80 minutes, and the desulfurization performance is lower than that of Examples 3 and 4 in the present invention.

[0049] The preferred embodiments of the present invention disclosed above are intended only to help illustrate the present invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the present invention to specific embodiments. Obviously, many modifications and variations are possible based on the contents of this specification. These embodiments are selected and described in detail in this specification to better explain the principles and practical applications of the present invention, thereby enabling those skilled in the art to better understand and utilize the present invention. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A guanidine salt conjugated polyacid functionalized deep eutectic solvent liquid phase desulfurizer, characterized by: The novel guanidine salt conjugated polyacid functionalized low eutectic solvent liquid phase desulfurizer is prepared by dissolving polymetallic acid salt in a guanidine salt functionalized low eutectic solvent, wherein the polymetallic acid salt is phosphomolybdic acid; wherein the guanidine salt is 1,1,3,3-tetramethylguanidine; and the low eutectic solvent is a choline-based low eutectic solvent.

2. The guanidine salt conjugated polyacid functionalized deep eutectic solvent liquid phase desulfurizer according to claim 1, characterized in that: The choline-based deep eutectic solvent is mainly prepared from choline chloride and a hydrogen bond donor; the hydrogen bond donor is ethylene glycol, glycerol or urea.

3. The electrochemical treatment method of the guanidine salt conjugated polyacid functionalized deep eutectic solvent liquid phase desulfurization agent according to any one of claims 1-2, characterized in that: The electrochemical strengthening method mainly involves cathode electrochemical strengthening through an electrochemical strengthening device, with a controlled current of 0.01A and an electrochemical strengthening time of mainly 2-24 hours. The electrochemical strengthening device mainly comprises a DC power supply and an H-type electrochemical cell, a guanidine salt conjugated polyacid functionalized low eutectic solvent solution is placed in the cathode chamber, and the anode chamber is a 0.1 mol / L potassium bicarbonate aqueous solution, which is isolated by a proton exchange membrane, and the electrode is made of carbon paper.

4. The method for using the guanidine salt conjugated polyacid functionalized deep eutectic solvent liquid phase desulfurizer according to any one of claims 1 to 3, characterized in that: The hydrogen sulfide is removed by gas-liquid absorption reactor, and the absorption temperature is 25-75 o C, the flow rate is 50-200 mL / min, the concentration is 500-2000 mg / m 3 The optimal guanidine salt conjugated polyacid functionalized deep eutectic solvent liquid phase desulfurization agent TPDES@5% can maintain 100% desulfurization efficiency for 180 minutes; the optimal guanidine salt conjugated polyacid functionalized deep eutectic solvent liquid phase desulfurization agent E after electrochemical treatment 24h TPDES@5% can maintain 100% desulfurization efficiency for 570 minutes; the gas-liquid absorption reactor is mainly a bubbling absorber.

5. The regeneration method of the guanidine salt conjugated polyacid functionalized deep eutectic solvent liquid phase desulfurizer according to any one of claims 1 to 3, characterized in that: The regeneration method of TPDES is to pass 75 o C heating and passing air with a flow rate of 200mL / min, the regeneration time is 4-6h; the regeneration method of ETPDES after electrochemical treatment is to pass through 75 o C was heated and air was blown off at a flow rate of 200 mL / min for a regeneration time of 24 h, and then electrochemical treatment was performed with an electrochemical treatment current of 0.01 A and an electrochemical time of 24 h.

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