A liquid-phase high-sulfur-capacity catalyst, its preparation, uses and regeneration method
By preparing a liquid-phase high-sulfur-capacity catalyst containing components such as ferric ammonium citrate, the problems of low sulfur capacity and poor stability of existing desulfurization catalysts have been solved, achieving efficient and stable hydrogen sulfide purification, which is suitable for industrial environments with limited space.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CHINA PETROLEUM & CHEMICAL CORP
- Filing Date
- 2022-10-25
- Publication Date
- 2026-05-19
AI Technical Summary
Existing desulfurization catalysts have low sulfur capacity, iron ions readily react with sulfur ions in hydrogen sulfide to form iron sulfide precipitates, poor stability, easy failure, and difficulty in regeneration, resulting in rapid degradation of catalyst performance and unsuitability for applications with limited space.
A liquid-phase high-sulfur-capacity catalyst was prepared by using a composite absorbent of ferric ammonium citrate and tetrasodium diacetate of glutamic acid, stabilizers of sodium nitrite and sodium nitrate, pH buffer of sodium acetate, sulfur modifiers of triethanolamine and polyethyleneimine, and corrosion inhibitor of hexamethylenetetramine. The high and stable concentration of ferric ions was ensured by air aeration or electrochemical oxidation regeneration.
It achieves high sulfur capacity (8-16 g/L), high stability, fast reaction speed and high desulfurization efficiency, adapts to varying feed gas composition, reduces equipment size and meets the needs of green circular economy.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of desulfurization catalyst technology, and in particular to a liquid-phase high-sulfur-capacity catalyst and its preparation, use and regeneration method. Background Technology
[0002] Hydrogen sulfide is a gaseous pollutant that must be eliminated or controlled. Hydrogen sulfide in gases such as natural gas and associated gas from oil fields requires removal and harmless treatment. Over the past 20 years, due to increasingly stringent environmental protection requirements, countries worldwide have attached great importance to the development and application of sulfur recovery technologies. Numerous sulfur recovery technologies have been applied, each with different principles, characteristics, and applicable scopes. For the treatment of acidic gases containing hydrogen sulfide (H2S), industrial production often employs fixed-bed catalytic oxidation and liquid-phase direct oxidation processes. Fixed-bed catalytic oxidation mainly includes the Claus sulfur recovery process and various improved processes. Compared to fixed-bed catalytic oxidation, liquid-phase oxidation desulfurization technology has advantages such as cleanliness, high efficiency, operation under ambient temperature and pressure, regenerable desulfurizing agents, and low operating costs. It has good application potential in industrial environments such as offshore gas fields, floating liquefied natural gas (FLNG) units, floating production storage and offloading (FPSO) units, or onshore marginal oil and gas fields.
[0003] Liquid-phase direct oxidation, also known as wet oxidation desulfurization, refers to a natural gas desulfurization method that uses a solution containing an oxygen carrier to oxidize H2S in natural gas into elemental sulfur. The reduced oxidant is then regenerated by air to restore its oxidizing capacity. Research on this type of method began in the 1920s and has since developed into over a hundred methods, of which more than twenty have industrial applications. Wet oxidation has the following characteristics: high desulfurization efficiency; it can convert H2S into elemental sulfur in one step without secondary pollution; it can operate at both ambient temperature and under pressure; most desulfurizing agents can be regenerated, resulting in low operating costs. However, when the CO2 content in the feed gas is too high, the reaction in the liquid phase will slow down rapidly due to the decrease in the solution pH, thus affecting the mass transfer rate of H2S absorption and the economics of the plant. Representative liquid-phase direct oxidation processes include the Stretfoul oxidation process and the LO-CAT process.
[0004] The Stretfoul oxidation process, developed in 1959 by Northwest Gas Company in the United States, is a desulfurization process with thousands of units currently in operation worldwide. This process uses vanadium as the basic catalyst for desulfurization and sodium anthraquinone-2,7-dicarate (ADA) as the regenerated oxygen carrier for the reduced vanadium, with carbonates used as the washing medium. The process has several drawbacks: difficulty in recovering sulfur particles from flotation, leading to filter clogging; high chemical consumption due to byproducts; poor sulfur quality; minimal effect on carbon disulfide (CS2), carbonyl sulfide (COS), and thiols; difficulty in treating hazardous waste liquid, potentially causing secondary pollution; and highly irritating gases.
[0005] The LO-CAT process is a proprietary technology developed by Merichem, Inc. in the United States. The reaction process takes place in a catalyst-water solution system under isothermal conditions, using a chelated iron catalyst to convert H2S in the gaseous stream into elemental sulfur, which is then removed. The LO-CAT process can be divided into two parts: elemental sulfur generation and iron catalyst regeneration. The LO-CAT process has been proven reliable in practice, with over 180 installations worldwide, distributed across industries such as petrochemicals, natural gas, coal gasification, and urban sanitation. It has been recognized as a best-of-use technology by the U.S. Environmental Protection Agency. However, to reduce chelate degradation, the LO-CAT catalyst uses a low concentration of chelated iron, resulting in a low sulfur capacity. This necessitates a large reactor in engineering applications, leading to a large plant size and footprint, making it unsuitable for space-constrained environments.
[0006] Domestic efforts have also been made to improve the LO-CAT process, including the FD method, the ATMP-Fe method, and the gentianic acid-iron method. The FD method uses sulfosalicylic acid complex salts as desulfurizing agents. Sulfosalicylic acid is cheaper than EDTA, and it reacts with Fe... 3+ The K value of the complex and EDTA-Fe 3+ The complexation K value is similar to that of Fe. 2+ Complexation K value ratio of EDTA-Fe 2+ The regeneration time is relatively long due to the lower regeneration rate required by the FD method. The ATMP-Fe method also suffers from regeneration difficulties. In the gentianic acid-iron method, the iron salt is stabilized by tartaric acid, and the process involves Fe... 3+ Oxidation of H2S, gentian acid oxidation of Fe 2+ Gentian acid is oxidized by air to form a recycling system, but it also has problems such as a long recycling cycle.
[0007] CN106237844B discloses a complexed iron desulfurization liquid for wet desulfurization and its preparation method, including an antioxidant, a nonionic surfactant, a defoamer, a complexed iron catalyst, and water. However, the preparation conditions need to be controlled, and Fe(OH)3 is added in 4-6 batches. The preparation method is complex and has poor stability. Furthermore, according to the specific embodiments of this patent, to achieve a desulfurization rate of over 99%, the desulfurization time needs to be over 5 days, resulting in a long desulfurization time, low processing efficiency, and hindering industrial application. Additionally, the desulfurization liquid treats a fixed hydrogen sulfide content in the raw gas and does not contain CO2, which affects the desulfurization process, making it unsuitable for the variable real-world desulfurization applications.
[0008] The literature "ISS Complexed Iron-Polyphenol Catalyst Desulfurization Technology" published in December 2004 disclosed a complexed iron-polyphenol desulfurization catalyst. The main active components are complexed iron compounds and polyphenols. The complex of variable valence metallic iron is used as the desulfurization catalyst, and the polyphenols are used as the regeneration catalyst. During the desulfurization process, organic sulfur is first absorbed and converted, and then oxidized into elemental sulfur by the catalyst and removed. However, a large number of side reactions still occur during the desulfurization and regeneration process. At the same time, the matching desulfurization process and equipment are complex, and the desulfurization rate can only reach 97%. There are many problems such as low desulfurization efficiency and unfavorable to industrial promotion.
[0009] CN111592474A discloses a method for preparing a complexed iron catalyst for wet desulfurization, comprising the following steps: (1) preparing sulfophthalic acid; (2) reacting sulfophthalic acid with sodium hydroxide to prepare compound I; (3) reacting compound I with cobalt chloride to prepare compound II; (4) reacting compound I with an iron-containing compound to prepare compound III; (5) reacting compound II with compound III to obtain compound IV; (6) preparing a stabilizer; (7) mixing compound IV with a dual stabilizer, heating, cooling, and drying to obtain the catalyst. However, the preparation conditions of this patented catalyst are quite demanding. Not only does the raw material need to be fuming sulfuric acid, a hazardous chemical, but the temperature for preparing the catalyst is also at least 200°C. The highest sulfur capacity of the prepared catalyst is only 0.2%, which does not meet the current requirements for desulfurization complexed iron catalysts.
[0010] Based on the existing technology, current desulfurization catalysts have low iron content and low sulfur capacity (4-7 g / L), resulting in large catalyst usage and large-scale equipment, which is not conducive to the lightweight application requirements of skid-mounted sulfur recovery units. However, simply increasing the iron concentration will cause the iron ions in the catalyst to react with the sulfur ions of hydrogen sulfide to form iron sulfide precipitates, leading to problems such as catalyst sedimentation, degradation, and failure, resulting in rapid degradation of catalyst performance. Therefore, finding a desulfurization catalyst with high sulfur capacity, simple preparation process, fast absorption rate, easy regeneration, high desulfurization efficiency, non-toxicity, simplifies desulfurization equipment, and has low solution consumption and by-product formation rates after adding stabilizers and anti-degradation agents, and with an economical process, has become an urgent technical problem to be solved. Summary of the Invention
[0011] To address the technical problems mentioned above, this invention provides a liquid-phase high-sulfur-capacity catalyst, which solves the problems of low sulfur capacity, easy formation of iron sulfide precipitate by iron ions in the catalyst with sulfur ions in hydrogen sulfide, poor stability, easy failure, and difficulty in regeneration of existing desulfurization catalysts. This makes the desulfurization catalyst of this invention applicable to the purification of natural gas in onshore marginal oil and gas fields, offshore gas fields, floating liquefied natural gas (FLNG) units, and offshore floating production storage and offloading (FPSO) units.
[0012] The catalyst has a sulfur capacity of 8–16 g / L and a ferric ion concentration of 30,000–60,000 mg / L.
[0013] Furthermore, the catalyst is prepared using composite absorbent, stabilizer, pH buffer, sulfur modifier, corrosion inhibitor and deionized water as raw materials.
[0014] Furthermore, the composite absorbent is ferric ammonium citrate and tetrasodium diacetate of glutamate, used to absorb hydrogen sulfide;
[0015] Furthermore, the stabilizer is sodium nitrite and sodium nitrate, used to stabilize the composite absorbent;
[0016] Furthermore, the pH buffer is sodium acetate, used to adjust the pH of the catalyst;
[0017] Furthermore, the sulfur modifier is triethanolamine and polyethyleneimine, used to improve the quality of the generated sulfur;
[0018] Furthermore, the corrosion inhibitor is p-hexamethylenetetramine, used to reduce the corrosiveness of the solution.
[0019] Furthermore, the iron ammonium citrate in the catalyst comprises 15-20% by mass;
[0020] Furthermore, the tetrasodium glutamate diacetate in the catalyst comprises 3-6% by mass;
[0021] Furthermore, the sodium nitrite in the catalyst comprises 3-7% by mass;
[0022] Furthermore, the sodium nitrate in the catalyst comprises 10-20% by mass;
[0023] Furthermore, the sodium acetate in the catalyst comprises 1-3% by mass;
[0024] Furthermore, the triethanolamine in the catalyst comprises 6-15% by mass;
[0025] Furthermore, the polyethyleneimine in the catalyst comprises 2-6% by mass;
[0026] Furthermore, the hexamethylenetetramine in the catalyst is 1-3% by mass.
[0027] The present invention also provides a method for preparing the catalyst described above, comprising the following steps:
[0028] S1: Add the pH buffer to deionized water, stir until completely dissolved, then add acetic acid dropwise to adjust the pH to 6.2-7.0 to obtain solution A1;
[0029] S2: Add the stabilizer to the solution A1 obtained in S1 and stir continuously to mix it thoroughly and evenly to obtain solution A2;
[0030] S3: After heating the solution A2 obtained in S2 to a constant temperature and keeping it at that temperature, add the composite absorbent and stir continuously until it is completely dissolved and mixed evenly to obtain solution A3;
[0031] S4: Add the sulfur modifier to the solution A3 obtained in S3, stir evenly, and obtain solution A4;
[0032] S5: Add the corrosion inhibitor to solution A4 obtained in S4, stir until completely dissolved, and cool to room temperature to obtain a liquid-phase high sulfur capacity catalyst.
[0033] Furthermore, in step S3, the temperature at which the temperature is heated to a constant temperature is 35–45°C, and the holding time is 30–60 minutes.
[0034] Furthermore, the catalyst has a pH value of 6.2 to 7.0.
[0035] The present invention also provides a use of the catalyst described above, wherein the catalyst is used in a desulfurization reaction.
[0036] The catalyst is used to remove hydrogen sulfide from a mixed gas containing hydrogen sulfide. The reaction steps are as follows: the catalyst is thoroughly mixed with the gas containing hydrogen sulfide through a mixing pipe, spray, or mist. At a temperature of 5–50°C, the hydrogen sulfide dissolves in the catalyst and is reduced to elemental sulfur. The elemental sulfur forms sulfur particles suspended in the catalyst, which gradually aggregate, nucleate, and grow. The elemental sulfur is then separated from the catalyst by pressure filtration and centrifugation.
[0037] The reaction formula for desulfurization using the catalyst is as follows:
[0038] C6H8Fe(III)NO7+H2S+O2→C6H8Fe(II)NO7+S+H2O
[0039] C6H8Fe(III)NO7 is ferric ammonium citrate, with the ferric ion having a oxidation state of +3; C6H8Fe(II)NO7 is ferrous ammonium citrate, with the ferric ion having a oxidation state of +2.
[0040] The present invention also provides a method for regenerating the catalyst described above:
[0041] Catalyst regeneration is achieved through air aeration or electrochemical oxidation, which converts ferrous ammonium citrate in the catalyst back into ferric ammonium citrate.
[0042] The beneficial effects of this invention are as follows:
[0043] 1. This invention provides a liquid-phase high sulfur capacity catalyst with a sulfur capacity of 8-16 g / L. Compared with existing desulfurization catalysts with a sulfur capacity of 4-7 g / L, the high sulfur capacity prepared by this invention results in a higher concentration of ferric ions, ranging from 30,000 to 60,000 mg / L, which enhances hydrogen sulfide absorption and reaction capabilities. Furthermore, the ferric ions in the catalyst do not react with sulfur ions in hydrogen sulfide to form iron sulfide precipitate, effectively preventing catalyst failure and regeneration difficulties. This allows for a smaller catalyst volume and quantity to be used in process designs with a certain hydrogen sulfide purification capacity, thereby effectively reducing the scale of the equipment. The generated elemental sulfur can also be recycled and reused, meeting the requirements of a green circular economy.
[0044] 2. The catalyst prepared by this invention has good stability, can be used in the temperature range of 5 to 50°C, is not easily degraded, and after 3 months of storage, the concentration of ferric ions in the catalyst still remains above 99% of the initial concentration.
[0045] 3. The catalyst prepared by this invention has a fast reaction rate in the desulfurization reaction and can react rapidly with hydrogen sulfide gas in the raw material gas, so as to realize the absorption of hydrogen sulfide and immediate conversion, resulting in high treatment efficiency.
[0046] 4. The catalyst prepared by this invention has strong regeneration performance. After 10 rounds of absorption reaction and regeneration cycle, the concentration of ferric ions in the catalyst is still maintained at more than 98% of the initial concentration, and there will be no significant decrease in concentration if it is used continuously.
[0047] 5. The catalyst solution prepared by this invention has a pH value of 6.2 to 7.0, strong applicability, and can treat source gas with a hydrogen sulfide content of 0 to 100%. Even if there is CO2 in the raw gas that reduces the reaction rate, it will not significantly reduce the desulfurization rate of the catalyst.
[0048] 6. The catalyst prepared by this invention has the advantages of simplified preparation, use and regeneration processes and equipment, fast absorption of hydrogen sulfide, easy regeneration, high desulfurization efficiency, non-toxicity, low consumption of catalyst solution and low rate of by-reaction product formation after the addition of stabilizers, and economical and reasonable process. It can be used in desulfurization processes, can effectively reduce the scale of equipment, and has good industrial application value. It is especially suitable for the development needs of liquefied natural gas systems and sulfur recovery devices that require simple processes and equipment, lightweight, small footprint, and high desulfurization efficiency. Detailed Implementation
[0049] Example 1 Sample 1
[0050] The liquid-phase high-sulfur-capacity catalyst involved in Sample 1 of this embodiment is prepared using a composite absorbent, a stabilizer, a pH buffer, a sulfur modifier, a corrosion inhibitor, and deionized water as raw materials. The composite absorbent is ferric ammonium citrate and tetrasodium diacetate of glutamic acid; the stabilizer is sodium nitrite and sodium nitrate; the pH buffer is sodium acetate; the sulfur modifier is triethanolamine and polyethyleneimine; and the corrosion inhibitor is p-hexamethylenetetramine.
[0051] The catalyst comprises, by mass percentage, 15% ferric ammonium citrate, 3% tetrasodium glutamate diacetate, 3% sodium nitrite, 10% sodium nitrate, 2% sodium acetate, 6% triethanolamine, 2% polyethyleneimine, and 1% hexamethylenetetramine, with the remainder being deionized water.
[0052] The preparation method of the catalyst for Sample 1 in this embodiment is as follows:
[0053] S1: Add the pH buffer to deionized water, stir until completely dissolved, then add acetic acid dropwise to adjust the pH to 6.2-7.0 to obtain solution A1;
[0054] S2: Add the stabilizer to the solution A1 obtained in S1 and stir continuously to mix it thoroughly and evenly to obtain solution A2;
[0055] S3: Heat the solution of S2 mixed evenly to 40°C and keep it at that temperature for 30 minutes. Then add the composite absorbent and stir continuously until it is completely dissolved and mixed evenly to obtain solution A3.
[0056] S4: Add the sulfur modifier to the solution A3 obtained in S3, stir evenly, and obtain solution A4;
[0057] S5: Add the corrosion inhibitor to solution A4 obtained in S4, stir until completely dissolved, and cool to room temperature to obtain a liquid-phase high sulfur capacity catalyst.
[0058] The pH value of the catalyst sample prepared by the above steps is 6.9.
[0059] In this embodiment, the catalyst in Sample 1 is used for the removal of hydrogen sulfide, and the reaction steps are as follows:
[0060] At a temperature of 25°C, the catalyst was injected into the desulfurization equipment, and hydrogen sulfide was removed by gas-liquid contact using a mixed-flow method. Specifically, the catalyst flow rate was controlled by adjusting the valves, and the reactor liquid level was kept stable. A gas cylinder containing a mixture of 25% H2S and 75% CO2 (by volume) was connected to the reactor inlet, and the mixture was introduced into the equipment at a constant gas flow rate of 1 L / min. A hydrogen sulfide concentration detector was installed at the tail gas outlet to detect the hydrogen sulfide concentration. Based on the tail gas concentration, the treatment efficiency was calculated to be 99.996%, and the sulfur capacity of the catalyst in sample one of this embodiment was determined to be 8.3 g / L.
[0061] The catalyst regeneration method for Sample 1 in this embodiment is as follows: oxygen is introduced into the liquid-phase high sulfur capacity catalyst using an electrochemical oxidation method to convert ferrous ammonium citrate in the catalyst back into ferric ammonium citrate. After regeneration, the concentration of the effective component in the catalyst solution is maintained at 99.9% of the initial concentration, and the regeneration time is 3.0 h.
[0062] In this embodiment, the initial concentration of ferric ions in the catalyst sample 1 was 32,000 mg / L. After being stored for 3 months without participating in the desulfurization reaction, the concentration of ferric ions in the catalyst was still 32,000 mg / L, that is, the concentration retention rate of ferric ions in the catalyst was 100%.
[0063] After 10 rounds of absorption reaction and regeneration cycle, the concentration of ferric ions in the catalyst of Sample 1 in this embodiment was 31990 mg / L, that is, the concentration retention rate of ferric ions in the catalyst was 99.968%.
[0064] Example 2 Sample 2
[0065] The liquid-phase high-sulfur-capacity catalyst involved in Sample 2 of this embodiment is prepared using a composite absorbent, a stabilizer, a pH buffer, a sulfur modifier, a corrosion inhibitor, and deionized water as raw materials. The composite absorbent is ferric ammonium citrate and tetrasodium diacetate of glutamic acid; the stabilizer is sodium nitrite and sodium nitrate; the pH buffer is sodium acetate; the sulfur modifier is triethanolamine and polyethyleneimine; and the corrosion inhibitor is p-hexamethylenetetramine.
[0066] The catalyst comprises, by mass percentage, 17% ferric ammonium citrate, 4% tetrasodium glutamate diacetate, 5% sodium nitrite, 20% sodium nitrate, 3% sodium acetate, 9% triethanolamine, 3% polyethyleneimine, and 3% hexamethylenetetramine, with the remainder being deionized water.
[0067] The preparation method of the catalyst for sample two in this embodiment is as follows:
[0068] S1: Add the pH buffer to deionized water, stir until completely dissolved, then add acetic acid dropwise to adjust the pH to 6.2-7.0 to obtain solution A1;
[0069] S2: Add the stabilizer to the solution A1 obtained in S1 and stir continuously to mix it thoroughly and evenly to obtain solution A2;
[0070] S3: Heat the solution of S2 mixed evenly to 40°C and keep it at that temperature for 30 minutes. Then add the composite absorbent and stir continuously until it is completely dissolved and mixed evenly to obtain solution A3.
[0071] S4: Add the sulfur modifier to the solution A3 obtained in S3, stir evenly, and obtain solution A4;
[0072] S5: Add the corrosion inhibitor to solution A4 obtained in S4, stir until completely dissolved, and cool to room temperature to obtain a liquid-phase high sulfur capacity catalyst.
[0073] The pH value of the catalyst sample prepared by the above steps is 6.7.
[0074] In this embodiment, the catalyst in sample two is used for the removal of hydrogen sulfide, and the reaction steps are as follows:
[0075] At a temperature of 25°C, the catalyst was injected into the desulfurization equipment, and hydrogen sulfide was removed by gas-liquid contact using a spray method. Specifically, the catalyst flow rate was controlled by adjusting the valves, and the reactor liquid level was maintained stable. A cylinder containing 100% H2S by volume was connected to the reactor inlet, and this gas was introduced into the equipment at a constant gas velocity. A hydrogen sulfide concentration detector was installed at the tail gas outlet to detect the hydrogen sulfide concentration. Based on the tail gas concentration, the treatment efficiency was calculated to be 99.992%, and the sulfur capacity of the catalyst in sample two of this embodiment was determined to be 11.2 g / L.
[0076] The catalyst regeneration method for Sample 2 in this embodiment is as follows: oxygen is introduced into the liquid-phase high sulfur capacity catalyst using an electrochemical oxidation method to convert ferrous ammonium citrate in the catalyst back into ferric ammonium citrate. After regeneration, the concentration of the effective component in the catalyst solution is maintained at 99.9% of the initial concentration, and the regeneration time is 3.2 hours.
[0077] In this example, the initial concentration of ferric ions in the catalyst of sample two was 36,000 mg / L. After being stored for 3 months without participating in the desulfurization reaction, the concentration of ferric ions in the catalyst was still 36,000 mg / L, that is, the concentration retention rate of ferric ions in the catalyst was 100%.
[0078] After 10 rounds of absorption reaction and regeneration cycle, the concentration of ferric ions in the catalyst of sample two in this embodiment was 35970 mg / L, that is, the concentration retention rate of ferric ions in the catalyst was 99.916%.
[0079] Example 3 Sample 3
[0080] The liquid-phase high-sulfur-capacity catalyst involved in Sample 3 of this embodiment is prepared using a composite absorbent, a stabilizer, a pH buffer, a sulfur modifier, a corrosion inhibitor, and deionized water as raw materials. The composite absorbent is ferric ammonium citrate and tetrasodium diacetate of glutamic acid; the stabilizer is sodium nitrite and sodium nitrate; the pH buffer is sodium acetate; the sulfur modifier is triethanolamine and polyethyleneimine; and the corrosion inhibitor is p-hexamethylenetetramine.
[0081] The catalyst comprises, by mass percentage, 20% ferric ammonium citrate, 6% tetrasodium glutamate diacetate, 7% sodium nitrite, 15% sodium nitrate, 3% sodium acetate, 12% triethanolamine, 5% polyethyleneimine, and 2% hexamethylenetetramine, with the remainder being deionized water.
[0082] The preparation method of the three catalysts in this embodiment is as follows:
[0083] S1: Add the pH buffer to deionized water, stir until completely dissolved, then add acetic acid dropwise to adjust the pH to 6.2-7.0 to obtain solution A1;
[0084] S2: Add the stabilizer to the solution A1 obtained in S1 and stir continuously to mix it thoroughly and evenly to obtain solution A2;
[0085] S3: Heat the solution of S2 mixed evenly to 40°C and keep it at that temperature for 30 minutes. Then add the composite absorbent and stir continuously until it is completely dissolved and mixed evenly to obtain solution A3.
[0086] S4: Add the sulfur modifier to the solution A3 obtained in S3, stir evenly, and obtain solution A4;
[0087] S5: Add the corrosion inhibitor to solution A4 obtained in S4, stir until completely dissolved, and cool to room temperature to obtain a liquid-phase high sulfur capacity catalyst.
[0088] The pH value of the three catalysts prepared by the above steps is 6.6.
[0089] In this embodiment, the catalyst in sample three is used for the removal of hydrogen sulfide, and the reaction steps are as follows:
[0090] At a temperature of 25°C, the catalyst was injected into the desulfurization equipment, and hydrogen sulfide was removed by gas-liquid contact using a spray method. Specifically, the catalyst flow rate was controlled by adjusting the valves, and the reactor liquid level was maintained stable. A cylinder containing 100% H2S by volume was connected to the reactor inlet, and this gas was introduced into the equipment at a constant gas velocity. A hydrogen sulfide concentration detector was installed at the tail gas outlet to detect the hydrogen sulfide concentration. Based on the tail gas concentration, the treatment efficiency was calculated to be 99.996%, and the sulfur capacity of the catalyst in sample three in this embodiment was determined to be 13.6 g / L.
[0091] The catalyst regeneration method for sample three in this embodiment is as follows: oxygen is introduced into the liquid-phase high sulfur capacity catalyst using an electrochemical oxidation method to convert ferrous ammonium citrate in the catalyst back into ferric ammonium citrate. After regeneration, the concentration of the effective component in the catalyst solution is maintained at 99.9% of the initial concentration, and the regeneration time is 3.4 hours.
[0092] In this example, the initial concentration of ferric ions in the catalyst sample was 43,000 mg / L. After being stored for 3 months without participating in the desulfurization reaction, the concentration of ferric ions in the catalyst was still 43,000 mg / L, meaning that the concentration retention rate of ferric ions in the catalyst was 100%.
[0093] After 10 rounds of absorption reaction and regeneration cycle, the concentration of ferric ions in the catalyst of sample three in this embodiment was 42990 mg / L, that is, the concentration retention rate of ferric ions in the catalyst was 99.976%.
[0094] Example 4 Sample 4
[0095] The liquid-phase high-sulfur-capacity catalyst involved in Sample 4 of this embodiment is prepared using a composite absorbent, a stabilizer, a pH buffer, a sulfur modifier, a corrosion inhibitor, and deionized water as raw materials. The composite absorbent is ferric ammonium citrate and tetrasodium diacetate of glutamic acid; the stabilizer is sodium nitrite and sodium nitrate; the pH buffer is sodium acetate; the sulfur modifier is triethanolamine and polyethyleneimine; and the corrosion inhibitor is p-hexamethylenetetramine.
[0096] The catalyst comprises, by mass percentage, 16% ferric ammonium citrate, 4% tetrasodium glutamate diacetate, 6% sodium nitrite, 10% sodium nitrate, 2% sodium acetate, 6% triethanolamine, 2% polyethyleneimine, and 1% hexamethylenetetramine, with the remainder being deionized water.
[0097] The preparation method of the catalyst for sample four in this embodiment is as follows:
[0098] S1: Add the pH buffer to deionized water, stir until completely dissolved, then add acetic acid dropwise to adjust the pH to 6.2-7.0 to obtain solution A1;
[0099] S2: Add the stabilizer to the solution A1 obtained in S1 and stir continuously to mix it thoroughly and evenly to obtain solution A2;
[0100] S3: Heat the solution of S2 mixed evenly to 40°C and keep it at that temperature for 30 minutes. Then add the composite absorbent and stir continuously until it is completely dissolved and mixed evenly to obtain solution A3.
[0101] S4: Add the sulfur modifier to the solution A3 obtained in S3, stir evenly, and obtain solution A4;
[0102] S5: Add the corrosion inhibitor to solution A4 obtained in S4, stir until completely dissolved, and cool to room temperature to obtain a liquid-phase high sulfur capacity catalyst.
[0103] The pH value of the catalyst sample prepared by the above steps is 6.8.
[0104] In this embodiment, the catalyst in sample four is used for the removal of hydrogen sulfide, and the reaction steps are as follows:
[0105] Simulating an industrial desulfurization process, at a temperature of 25℃, a prepared liquid-phase high-sulfur-capacity catalyst was injected into the desulfurization tower, and natural gas containing 1000ppm hydrogen sulfide was introduced at a rate of 100m³. 3 The gas passes through the desulfurization tower at a rate of / h, and the hydrogen sulfide content at the natural gas outlet is detected to be 0ppm, with a desulfurization rate of 100%. Furthermore, the sulfur capacity of the catalyst in sample four of this embodiment is measured to be 12.8g / L.
[0106] The catalyst regeneration method for sample four in this embodiment is as follows: oxygen is introduced into the liquid-phase high sulfur capacity catalyst using an electrochemical oxidation method to convert ferrous ammonium citrate in the catalyst back into ferric ammonium citrate. After regeneration, the concentration of the effective component in the catalyst solution is maintained at 99.9% of the initial concentration, and the regeneration time is 3.3 hours.
[0107] In this example, the initial concentration of ferric ions in the catalyst of sample four was 50,000 mg / L. After being stored for 3 months without participating in the desulfurization reaction, the concentration of ferric ions in the catalyst was still 49,970 mg / L, that is, the retention rate of ferric ion concentration in the catalyst was 99.940%.
[0108] After 10 rounds of absorption reaction and regeneration cycle, the concentration of ferric ions in the catalyst of sample four in this embodiment was 49860 mg / L, that is, the concentration retention rate of ferric ions in the catalyst was 99.720%.
[0109] Example 5 Sample 5
[0110] The raw materials and preparation method for the catalyst prepared in Sample 5 of this embodiment are the same as those for Sample 4 in Example 4.
[0111] The catalyst in sample five of this embodiment is used for the removal of hydrogen sulfide, and the reaction steps are as follows:
[0112] Similarly simulating an industrial desulfurization process, at a temperature of 25℃, a prepared liquid-phase high-sulfur-capacity catalyst was injected into the desulfurization tower, along with natural gas containing 10,000 ppm hydrogen sulfide at a flow rate of 100 m³ / h. 3 The gas passes through the desulfurization tower at a rate of / h, and the hydrogen sulfide content at the natural gas outlet is detected to be 2ppm, with a desulfurization rate of 99.8%. Furthermore, the sulfur capacity of the catalyst in sample five of this embodiment is measured to be 13.8g / L.
[0113] The catalyst regeneration method for sample five in this embodiment is as follows: oxygen is introduced into the liquid-phase high sulfur capacity catalyst using an electrochemical oxidation method to convert ferrous ammonium citrate in the catalyst back into ferric ammonium citrate. After regeneration, the concentration of the effective component in the catalyst solution is maintained at 99.9% of the initial concentration, and the regeneration time is 3.3 hours.
[0114] Example 6 Sample Six
[0115] The liquid-phase high-sulfur-capacity catalyst involved in Sample Six of this embodiment is prepared using a composite absorbent, a stabilizer, a pH buffer, a sulfur modifier, a corrosion inhibitor, and deionized water as raw materials. The composite absorbent is ferric ammonium citrate and tetrasodium diacetate of glutamic acid; the stabilizer is sodium nitrite and sodium nitrate; the pH buffer is sodium acetate; the sulfur modifier is triethanolamine and polyethyleneimine; and the corrosion inhibitor is p-hexamethylenetetramine.
[0116] The catalyst comprises, by mass percentage, 19% ferric ammonium citrate, 6% tetrasodium glutamate diacetate, 6% sodium nitrite, 15% sodium nitrate, 3% sodium acetate, 6% triethanolamine, 3% polyethyleneimine, and 3% hexamethylenetetramine, with the remainder being deionized water.
[0117] The preparation method of the catalyst for sample six in this embodiment is as follows:
[0118] S1: Add the pH buffer to deionized water, stir until completely dissolved, then add acetic acid dropwise to adjust the pH to 6.2-7.0 to obtain solution A1;
[0119] S2: Add the stabilizer to the solution A1 obtained in S1 and stir continuously to mix it thoroughly and evenly to obtain solution A2;
[0120] S3: Heat the solution of S2 mixed evenly to 40°C and keep it at that temperature for 30 minutes. Then add the composite absorbent and stir continuously until it is completely dissolved and mixed evenly to obtain solution A3.
[0121] S4: Add the sulfur modifier to the solution A3 obtained in S3, stir evenly, and obtain solution A4;
[0122] S5: Add the corrosion inhibitor to solution A4 obtained in S4, stir until completely dissolved, and cool to room temperature to obtain a liquid-phase high sulfur capacity catalyst.
[0123] The pH value of the catalyst in sample six prepared by the above steps is 6.7.
[0124] The catalyst in sample six of this embodiment is used for the removal of hydrogen sulfide, and the reaction steps are as follows:
[0125] This embodiment simulates an industrial desulfurization process. At 25°C, a prepared liquid-phase high-sulfur-capacity catalyst is injected into the desulfurization tower, along with natural gas containing 1000 ppm hydrogen sulfide at a flow rate of 100 m³ / h. 3 The gas passes through the desulfurization tower at a rate of / h, and the hydrogen sulfide content at the natural gas outlet is detected to be 1ppm, with a desulfurization rate of 99.9%. Furthermore, the sulfur capacity of the catalyst in sample six of this embodiment is measured to be 15.2g / L.
[0126] The regeneration method of the catalyst in Sample 6 of this embodiment is as follows: oxygen is introduced into the liquid-phase high sulfur capacity catalyst by electrochemical oxidation to convert ferrous ammonium citrate in the catalyst back into ferric ammonium citrate. After regeneration, the concentration of the effective component in the catalyst solution is maintained at 99.9% of the initial concentration, and the regeneration time is 3.5 hours.
[0127] In this example, the initial concentration of ferric ions in the catalyst of sample six was 60,000 mg / L. After being stored for 3 months without participating in the desulfurization reaction, the concentration of ferric ions in the catalyst was still 59,980 mg / L, that is, the retention rate of ferric ion concentration in the catalyst was 99.967%.
[0128] After 10 rounds of absorption reaction and regeneration cycle, the concentration of ferric ions in the catalyst of sample six in this embodiment was 59850 mg / L, that is, the concentration retention rate of ferric ions in the catalyst was 99.750%.
[0129] Example 7 Sample 7
[0130] The raw materials and preparation method for the catalyst prepared in Sample 7 of this embodiment are the same as those for Sample 6 of Example 6.
[0131] The catalyst in sample seven of this embodiment is used for the removal of hydrogen sulfide, and the reaction steps are as follows:
[0132] Similarly simulating an industrial desulfurization process, at a temperature of 25℃, a prepared liquid-phase high-sulfur-capacity catalyst was injected into the desulfurization tower, along with natural gas containing 10,000 ppm hydrogen sulfide at a flow rate of 100 m³ / h. 3 The gas passes through the desulfurization tower at a rate of / h, and the hydrogen sulfide content at the natural gas outlet is detected to be 3ppm, with a desulfurization rate of 99.7%. Furthermore, the sulfur capacity of the catalyst in sample seven in this embodiment is measured to be 16.0g / L.
[0133] The catalyst regeneration method for sample seven in this embodiment is as follows: oxygen is introduced into the liquid-phase high sulfur capacity catalyst using an electrochemical oxidation method to convert ferrous ammonium citrate in the catalyst back into ferric ammonium citrate. After regeneration, the concentration of the effective component in the catalyst solution is maintained at 99.9% of the initial concentration, and the regeneration time is 3.5 hours.
[0134] Comparative Example 1 Sample 8
[0135] This comparative example uses a conventional desulfurization catalyst from existing technology to desulfurize a mixture containing hydrogen sulfide. At 25°C, the catalyst is injected into the desulfurization equipment, and hydrogen sulfide is removed through gas-liquid contact using a mixed-flow pipeline method. Specifically, the catalyst flow rate is controlled by adjusting valves, and the reactor liquid level is maintained stable. A gas cylinder containing a mixture of 25% H2S and 75% CO2 (by volume) is connected to the reactor inlet, and the mixture is introduced into the equipment at a constant gas rate of 1 L / min. A hydrogen sulfide concentration detector is installed at the tail gas outlet of the desulfurization equipment to detect the hydrogen sulfide concentration. Based on the tail gas concentration, the treatment efficiency is calculated to be 98.0%, and the sulfur capacity of catalyst sample eight in this comparative example is determined to be 6.2 g / L.
[0136] The regeneration method for the catalyst in this comparative sample eight is as follows: oxygen is introduced into the conventional desulfurization catalyst in the prior art using an electrochemical oxidation method. After regeneration, the concentration of the effective component in the catalyst solution is 96.0% of the initial concentration, and the regeneration time is 4.3 hours.
[0137] In summary, the experimental results of Examples 1-7 and Comparative Example 1 are compared in Tables 1 and 2:
[0138] Table 1
[0139]
[0140] As shown in Table 1, the liquid-phase high-sulfur-capacity catalyst of this invention has a higher sulfur capacity than conventional desulfurization catalysts in the prior art. Furthermore, its hydrogen sulfide treatment efficiency and the concentration retention rate of the catalyst solution after regeneration are both higher than those of conventional desulfurization catalysts in the prior art, exhibiting advantages such as high desulfurization efficiency and good regeneration stability. Simultaneously, the regeneration time of the liquid-phase high-sulfur-capacity catalyst of this invention is shorter, saving 18-30% of the regeneration time compared to conventional desulfurization catalysts in the prior art, further shortening the desulfurization process time and accelerating the desulfurization process.
[0141] Table 2
[0142]
[0143] As shown in Table 2, the catalyst prepared by this invention has good stability and is not easily degraded. After 3 months of storage, the concentration of ferric ions in the catalyst still remains above 99% of the initial concentration. At the same time, the catalyst prepared by this invention has strong regeneration performance. After 10 rounds of absorption reaction and regeneration cycle, the concentration of ferric ions in the catalyst still remains above 98% of the initial concentration.
[0144] It should be understood that the present invention is not limited to the content already described above, and various modifications and changes can be made without departing from its scope. The scope of the present invention is limited only by the appended claims.
Claims
1. A liquid-phase high-sulfur-capacity catalyst, characterized in that, The catalyst has a sulfur capacity of 8–16 g / L and a ferric ion concentration of 30,000–60,000 mg / L. The catalyst is prepared using composite absorbent, stabilizer, pH buffer, sulfur modifier, corrosion inhibitor and deionized water as raw materials; The composite absorbent is ferric ammonium citrate and tetrasodium diacetate of glutamic acid, or the stabilizer is sodium nitrite and sodium nitrate, or the pH buffer is sodium acetate, or the sulfur modifier is triethanolamine and polyethyleneimine, or the corrosion inhibitor is p-hexamethylenetetramine. The ferric ammonium citrate is 15-20% by mass in the catalyst, or the tetrasodium glutamate diacetate is 3-6% by mass in the catalyst, or the sodium nitrite is 3-7% by mass in the catalyst, or the sodium nitrate is 10-20% by mass in the catalyst, or the sodium acetate is 1-3% by mass in the catalyst, or the triethanolamine is 6-15% by mass in the catalyst, or the polyethyleneimine is 2-6% by mass in the catalyst, or the hexamethylenetetramine is 1-3% by mass in the catalyst.
2. A method for preparing the catalyst according to claim 1, characterized in that, Includes the following steps: S1: Add the pH buffer to deionized water, stir until completely dissolved, then add acetic acid dropwise to adjust the pH to 6.2-7.0 to obtain solution A1; S2: Add the stabilizer to the solution A1 obtained in S1 and stir continuously to mix it thoroughly and evenly to obtain solution A2; S3: After heating the solution A2 obtained in S2 to a constant temperature and keeping it at that temperature, add the composite absorbent and stir continuously until it is completely dissolved and mixed evenly to obtain solution A3; S4: Add the sulfur modifier to the solution A3 obtained in S3, stir evenly, and obtain solution A4; S5: Add the corrosion inhibitor to solution A4 obtained in S4, stir until completely dissolved, and cool to room temperature to obtain a liquid-phase high sulfur capacity catalyst.
3. The method for preparing the catalyst according to claim 2, characterized in that, The temperature reached during the S3 heating process is 35–45°C, and the holding time is 30–60 minutes.
4. The method for preparing the catalyst according to claim 2, characterized in that, The catalyst has a pH value of 6.2 to 7.
0.
5. Use of the catalyst according to claim 1, characterized in that, The catalyst is used in the desulfurization reaction.
6. The use of the catalyst according to claim 5, characterized in that, The catalyst is used to remove hydrogen sulfide from a mixed gas containing hydrogen sulfide. The reaction steps are as follows: the catalyst is fully mixed with the mixed gas containing hydrogen sulfide through a mixing pipe, spray or spray. At a temperature of 5 to 50°C, the hydrogen sulfide will dissolve in the catalyst and be reduced to elemental sulfur. The elemental sulfur and the catalyst are then separated by pressure filtration and centrifugation.
7. A method for regenerating the catalyst according to claim 1, characterized in that, The catalyst is regenerated by air aeration or electrochemical oxidation.