Method for absorbing and removing sulfide

Abstract

The invention relates to a method for absorbing and removing sulfides. The method comprises the following steps: contacting sulfide-containing gas to be treated with a solution containing a compound with the following structural formula, r1 is hydrogen or C1-4 alkyl substituent, R2, R3 and R4 are respectively and independently selected from at least one of hydrogen, hydroxyl, C1-4 alkyl or alkoxy or hydroxyalkyl and heterocyclic substituent; the sulfide is selected from at least one of hydrogen sulfide, COS, CS2, mercaptan, thioether or disulfide. Compared with the prior art, the piperidine compound selected by the invention can efficiently and selectively purify and remove hydrogen sulfide and various types of organic sulfides such as COS, CS2, mercaptan, thioether, disulfide and the like, and the organic sulfur content in raw material gases such as natural gas, oilfield associated gas, refinery gas, blast furnace gas and the like is particularly high; h2S and total sulfur content in the material flow can be effectively reduced at the same time.

Description

Technical Field

[0001] The invention belongs to the technical field of gas desulfurization and purification, and relates to a method for absorbing and removing sulfides. Background Art

[0002] In energy logistics such as natural gas, associated gas, and refinery gas, the presence of sulfur-containing components such as hydrogen sulfide (H2S), carbonyl sulfide (COS), and mercaptans pose multiple hazards: on the one hand, H2S not only causes electrochemical corrosion of transmission pipelines, but its highly toxic properties (concentrations ≥10ppm can threaten human health) pose a hidden danger to production safety; on the other hand, organic sulfides such as COS and low-molecular-weight mercaptans can easily cause poisoning and inactivation of downstream chemical catalysts, and after entering the atmosphere, the sulfate aerosols and SO2 generated by oxidation will aggravate environmental problems such as acid rain and photochemical smog. In addition, these sulfides will still release strong odors even at trace concentrations at the ppb level. Based on this, my country's GB17820-2018 "Natural Gas" standard clearly requires that the H2S content in civil Class I natural gas be ≤6mg / m 3 , total sulfur ≤ 20mg / m 3 The limits for H2S and total sulfur in Class II gas are 20 mg / m 3 With 100mg / m 3 , and promote the industry to achieve efficient utilization of clean energy and ecological protection through deep desulfurization technology.

[0003] Refinery gas, as a derivative gas from the petroleum processing, can be divided into catalytic cracking dry gas / liquefied gas, coking dry gas / liquefied gas and other categories according to the process type. Influenced by the sulfur content of crude oil, this type of gaseous product generally carries complex sulfides such as hydrogen sulfide (H2S), carbonyl sulfide (COS), mercaptans and sulfides, posing a systemic technical challenge. When used as fuel in process heating furnaces, the sulfur dioxide (SO2) generated by the combustion of sulfides not only exceeds the 50mg / m3 set by GB31570-2015 "Petroleum Refining Industry Pollutant Emission Standards", but also exceeds the 50mg / m3 set by GB31570-2015 "Petroleum Refining Industry Pollutant Emission Standards". 3 Emission limits will further aggravate regional air pollution; when used as a chemical raw material, sulfur components will poison the active sites of catalysts, leading to chain problems such as reduced reaction efficiency, shortened device operation cycle, and excessive product impurities. In addition, the corrosive effect of sulfides on the transmission and distribution system significantly accelerates equipment degradation, posing a safety risk. For this reason, GB 11174-2011 "Liquefied Petroleum Gas" strictly limits the total sulfur content of commercial liquefied gas to ≤343mg / m 3 、H2S≤10mg / m 3 It is worth noting that blast furnace gas, as an important component of the industrial fuel system, contains H2S and COS, which also need to be desulfurized to control the SO2 concentration of the combustion exhaust gas in order to achieve the goal of clean energy application.

[0004] Alkanolamine absorption is a core technology for acid gas removal. Its solvent systems include polyolamines such as monoethanolamine (MEA), diethanolamine (DEA), methylmonoethanolamine (MMEA), diethylethanolamine (DEEA), triethanolamine (TEA), diisopropanolamine (DIPA), diglycolamine (DGA), and N-methyldiethanolamine (MDEA). Under conditions of reasonable plant design and optimized process parameters, the removal efficiency of traditional alkanolamine solvents for H2S and CO2 meets conventional purification requirements. However, the removal efficiency for organic sulfides such as carbonyl sulfide (COS) and mercaptans varies significantly. Experimental studies have shown that the removal efficiency of traditional alkanolamine systems for organic sulfides is generally limited: for example, the removal rates of the more alkaline MEA and DEA for methyl mercaptan are only 45%-50%, 20%-25% for ethyl mercaptan, and almost no removal of propyl mercaptan (0%-10%). The root cause of this phenomenon is that the acidity of H2S and CO2 far exceeds that of organic sulfides, causing them to preferentially undergo protonation reactions in the solvent, thereby inhibiting the dissolution and mass transfer of organic sulfur through a competitive absorption mechanism. Therefore, in acidic oil and gas treatment scenarios where high-concentration H2S / CO2 coexists with organic sulfur, traditional alcohol amine processes have difficulty achieving simultaneous and efficient removal. Although they can effectively control H2S and CO2 concentrations, they cannot meet the demand for deep purification of organic sulfur. This technical bottleneck urgently needs to be overcome through solvent development or process innovation.

[0005] In the refinery gas purification sector, while acidic gases such as H2S and CO2 can be efficiently removed through chemical absorption, the removal mechanism for organic sulfur compounds such as mercaptans, which is dominated by physical dissolution, significantly limits the mass transfer efficiency of traditional alcohol amine solvents (such as MEA and MDEA). To address the need for purification of high concentrations of mercaptans in liquefied petroleum gas, the current mainstream approach is an amine-alkali composite process: amine scrubbing is used to remove H2S, CO2, and some organic sulfur. An alkaline scrubber is then introduced to contact the liquefied petroleum gas with a countercurrent solution of NaOH, where the mercaptans are extracted through chemical conversion of the sodium mercaptan salt. While this process can achieve the majority of mercaptans removal, ensuring that the sulfur content of the liquefied petroleum gas product meets the requirements of the GB 11174-2011 standard, it also presents several challenges. First, the accumulation of polysulfides (such as disulfides) during the alkali solution regeneration process will trigger a back-extraction effect, resulting in a 30%-50% decrease in the regeneration alkali solution circulation efficiency, and ultimately forming a strong alkaline waste liquid containing sulfide and polysulfide. Its odor release and improper disposal can easily cause soil and water pollution; secondly, the alkali washing system has an efficiency of removing non-ionic organic sulfur such as sulfide and COS of less than 15%, which is difficult to meet the purification needs of complex sulfur forms; furthermore, the double-tower series process increases equipment investment by more than 40%, and the waste alkali solution neutralization treatment unit generates an additional 20%-30% operating cost. With the increase in the diversity of organic sulfur components (such as thiophene derivatives) and concentration (thiol content can reach 2000mg / m 3), the adaptability gap of the existing process will be further expanded, and it is urgent to develop a new composite desulfurization system with both chemical selectivity and physical adsorption characteristics.

[0006] In the field of complex sulfur-containing source gas purification, optimizing the mass transfer selectivity and reactivity of solvent systems is a key strategy for overcoming the bottleneck of organic sulfur removal. For traditional systems based on MDEA (N-methyldiethanolamine) or DIPA (diisopropanolamine), researchers generally use functional additive compounding techniques to enhance performance. For example, by introducing cyclic amines with thiol nucleophilic sites (such as piperazine), ionic liquids with COS hydrolysis catalysis (such as [BMIM][OAc]), or organic solvents with physical adsorption properties (such as sulfolane), multi-component composite solvent systems are constructed. Experimental results have confirmed that such improved systems can significantly increase the removal efficiency of methyl mercaptan to 80%-90% (compared to 45%-50% in the original system) and ethyl mercaptan to 50%-60% (compared to 20%-25% in the original system), while maintaining high removal efficiency for H2S and CO2. The synergistic effect stems from a physical-chemical synergistic effect: functional additives enhance the solubility of mercaptans through hydrogen bonding, catalyze the hydrolysis of COS into easily removable H2S, and leverage steric hindrance to mitigate the competitive absorption of H2S / CO2 with organic sulfur. However, the increased complexity of solvent formulations can lead to new problems such as the accumulation of degradation products, increased regeneration energy consumption, and increased corrosion risks. This is driving the development of third-generation desulfurization media, including novel zwitterionic solvents and metal-organic framework (MOF)-supported solvents.

[0007] Prior art CN 102051244A addresses the challenge of removing organic sulfur from highly acidic oil and gas by proposing a multi-mechanism synergistic composite solvent system. Using MDEA as a base solvent, this patent introduces a metal oxide catalyst, sulfur-containing compounds, and a physical solvent to achieve an H2S removal rate exceeding 99.9%, while simultaneously increasing COS and methyl mercaptan removal efficiencies to 85%-92% and 78%-85%, respectively. While its advantages stem from the synergistic effects of hydrolysis catalysis, chemical bonding, and physical dissolution, it also suffers from issues such as reduced mass transfer efficiency due to high solvent viscosity and insufficient removal of complex mercaptans.

[0008] Prior art CN102580473A develops a novel desulfurization system based on a combination of polyamidoamine dendrimers and alcoholamines. Composed of 1-15% PAMAM and 10-50% alcoholamine, the solvent leverages the dendrimer's three-dimensional cavity structure and terminal amino groups to achieve an H2S / CO2 selectivity ratio of 3.5-4.2, while simultaneously increasing the removal rates of methyl mercaptan and ethyl mercaptan to 65-72% and 40-48%, respectively, significantly outperforming conventional alcoholamine solvents. Its core advantage lies in the cavity size screening effect and hydrogen bonding synergy, but PAMAM's high synthesis cost and insufficient cyclic stability still require improvement.

[0009] Prior art CN105381686A proposes an acid gas purification technology based on benzylamine and its derivatives, achieving both low volatility and highly efficient organic sulfur removal through innovative molecular structure. This technology uses benzylamine or a functionalized derivative as the primary solvent. Its benzyl ring structure reduces the solvent's vapor pressure by 60%-80% compared to conventional MEA, significantly reducing operational losses. In terms of purification performance, the solvent system utilizes a synergistic effect of amino chemical adsorption and aromatic ring physical dissolution. While maintaining an H2S removal rate of >99%, it also increases the removal efficiencies of methyl mercaptan and COS to 70%-80% and 65-75%, respectively. This makes it particularly suitable for purifying sources containing complex organic sulfur compounds, such as refinery gas. However, the system's removal rate for sulfide ethers remains less than 40%, and the solvent synthesis cost increases by approximately 25% compared to conventional alcoholamine systems, requiring further optimization through the formulation of physical solvents or catalytic components.

[0010] However, most of the aforementioned methods use alkylolamines as the primary solvent, and utilize modifiers such as hindered amines to enhance the removal efficiency of organic sulfur. However, their ability to remove organic sulfur, such as carbonyl sulfide, remains limited, often failing to meet the complex and diverse organic sulfur removal requirements found in diverse feedstocks. When applied to industrial purification, most hindered amines possess extensive branching, resulting in high vapor pressures and significant evaporation losses during absorption operations. In terms of thermal and chemical stability, many types of hindered amines exhibit poor stability, leading to solvent degradation during recycling and significantly diminishing purification effectiveness. The corrosiveness of the reagents is also a key consideration in solvent evaluation, with less corrosive solvents being more environmentally friendly during plant cycles. In the industrial desulfurization field, traditional hindered amine solvents such as DIPA and TEA face multiple challenges due to their molecular structure. Their branched configuration results in significantly higher vapor pressures, 15-20 times higher than that of MDEA. Annual evaporation losses can reach 5%-8% when operated at 40-60°C in the absorption tower, increasing operating costs and exacerbating volatile organic compound (VOC) emissions. In terms of thermal stability, the high-temperature regeneration process at 120-140°C is prone to molecular chain breakage or oxidation side reactions. After 200 cycles, the solvent degradation rate exceeds 15%, resulting in a 30%-40% decrease in methyl mercaptan removal efficiency. Regarding chemical corrosion, hindered amines can corrode carbon steel equipment at a rate of up to 0.15-0.25 mm / year, necessitating the addition of corrosion inhibitors to maintain equipment integrity, but this increases costs by 10%-15%. Current technological trends focus on developing low-volatility cyclic amine systems, such as piperazine derivatives, with vapor pressures controllable below 0.3 kPa; exploring high-temperature resistant ionic liquid composite systems with thermal decomposition temperatures exceeding 200°C; and developing self-inhibiting solvents with the goal of reducing the corrosion rate to below 0.08 mm / year, thereby creating more stable and efficient industrial purification solutions.

[0011] In order to meet the increasingly stringent requirements for total sulfur removal, it is necessary to further optimize the solvent components to improve the absorption and solubility performance of different types of organic sulfur while improving the economy and practicality of the absorption process. Summary of the Invention

[0012] The present invention aims to provide a method for removing sulfides by absorption, addressing the problem of poor absorption and solubility of organic sulfur in absorption and removal processes. The piperidine compounds used in the present invention can efficiently and selectively purify and remove hydrogen sulfide and various types of organic sulfur compounds, such as COS, CS2, mercaptans, sulfides, and disulfides. Specifically, for feed gases such as natural gas, associated oilfield gas, refinery gas, and blast furnace gas, which contain particularly high levels of organic sulfur, the piperidine compounds can simultaneously effectively reduce the H2S and total sulfur content in the stream. Absorption tests have shown that the piperidine-based absorbent in the present invention exhibits enhanced organic sulfur absorption and solubility capabilities and removal efficiency, particularly for COS.

[0013] The purpose of the present invention can be achieved by the following technical solutions:

[0014] A method for removing sulfides by absorption comprises: contacting a gas to be treated containing sulfides with a solution containing a compound having the following structural formula;

[0015]

[0016] R1 is hydrogen or C 1～4 Alkyl substituents, R2, R3 and R4 are independently selected from hydrogen, hydroxyl, C 1～4 At least one of an alkyl, alkoxy, hydroxyalkyl, or heterocyclic substituent;

[0017] The sulfide is selected from at least one of hydrogen sulfide, COS, CS2, mercaptan, sulfide or disulfide.

[0018] In some specific embodiments, R1 is one of hydrogen, methyl or ethyl; R2, R3 and R4 are independently selected from one of hydrogen, hydroxyl, ethyl, propyl, butyl, ethanol, propanol, butanol, ethoxy, propoxy, butoxy, ethylamino, propylamino, butylamino, furyl or pyridyl.

[0019] In some specific embodiments, the present invention is used to remove hydrogen sulfide, COS, CS2, mercaptans, sulfides, and disulfides from oilfield associated gas, refinery gas, and blast furnace gas streams, and has a high removal efficiency for organic sulfur. Organic sulfur is a mixture of carbonyl sulfide and one or more of mercaptans, sulfides, or disulfides with carbon numbers between 1 and 4. The natural gas, oilfield associated gas, refinery gas, and blast furnace gas contain up to about 8 (mol)% H2S, about 3000 mg (as sulfur element) / Nm 3Organic sulfur. When processing natural gas, oilfield associated gas, refinery gas, blast furnace gas and other streams, the raw gas processing load can be higher and the absorption pressure can be lower. Under the premise of ensuring that the H2S and COS purification effect in the stream meets the relevant indicators, the total sulfur content in the purified gas can be significantly reduced by significantly increasing the solubility of the desulfurization solvent for organic sulfides such as methyl mercaptan.

[0020] In some specific embodiments, the compound is selected from at least one of 2-methylpiperidine, 3-methylpiperidine, 1,3-dimethylpiperidine, 4-methylpiperidine, 4-hydroxypiperidine, N-methylpiperidine, 3-(furan-2-yl)piperidine, 2-piperidinylethylamine, 4-methyl-piperidin-1-ylamine, and 3-(piperidin-2-yl)propan-1-ol.

[0021] In some specific embodiments, the mass concentration of the compound in the solution is 40-60%.

[0022] In some specific embodiments, the solution further comprises an organic amine; the mass ratio of the compound to the organic amine is 2:3 to 3:2.

[0023] In some specific embodiments, the organic amine is selected from at least one of alkylamines, alkylolamines, amides, phosphoramides, benzylamines, or derivatives of the above amine compounds.

[0024] In some specific embodiments, the organic amine is selected from at least one of monoethanolamine, diethanolamine, diisopropanolamine, diglycolamine, and N-methyldiethanolamine.

[0025] In some specific embodiments, the organic amine is N-methyldiethanolamine, the compound is 3-methylpiperidine, and the mass ratio of N-methyldiethanolamine to 3-methylpiperidine is 1:1. This absorption solution can achieve deep removal of organic sulfur, particularly carbonyl sulfide, while effectively removing H2S. Furthermore, compared to aniline compounds, the piperidine compounds of the present invention have better chemical stability and are less susceptible to deterioration. Compared to polyamine compounds, they have lower bubble point pressures and less volatilization losses. Their aqueous solutions are weakly alkaline, resulting in less corrosion to equipment.

[0026] In some specific embodiments, the total mass concentration of the compound and the organic amine in the solution is 40-60%.

[0027] In some specific embodiments, the total mass concentration of the compound and the organic amine in the solution is 40%.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] The piperidine compounds of the present invention, by selecting substituents such as methyl and hydroxyl groups, can effectively activate the reactivity of the amine group with COS, exhibit stronger basicity, enhance the reaction rate and reaction limit with COS, and simultaneously ensure good removal performance for other organic sulfides including mercaptans and sulfides, thereby achieving a lower level of total sulfur in the purified gas product and meeting the requirements of different raw material sulfide compositions, processing conditions and desulfurization indicators.

[0030] In addition, compared with polyamine compounds, the piperidine compounds of the present invention have lower synthesis costs and more economic advantages, lower bubble point pressure in aqueous solution, and less volatilization loss when recycled in the absorption-regeneration system; compared with aniline compounds, piperidine compounds have better chemical stability and are not easily decomposed and deteriorated, and their aqueous solutions are more alkaline and less acidic, which can reduce equipment corrosion. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a process flow chart of an absorption purification system in the present invention;

[0032] Description of the marks in the figure:

[0033] 1-Feed gas; 2-Purified gas; 3-Flash gas; 4-Acid gas; 5-Rich liquid from absorption tower; 6-Rich liquid from flash tank; 7-Rich liquid from heat exchanger; 8-Lean liquid from regeneration tower; 9-Lean liquid from heat exchanger; 10-Lean liquid from cooler; 11-Absorption tower; 12-Rich liquid flash tank; 13-Regeneration tower; 14-Regeneration lean liquid cooler; 15-Rich and lean liquid heat exchanger; 16-Regeneration tower top condenser; 17-Regeneration tower bottom reboiler. DETAILED DESCRIPTION

[0034] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0035] The present invention has discovered a piperidine compound that can efficiently and selectively purify and remove hydrogen sulfide and organic sulfides such as COS, CS2, mercaptans, sulfides, and disulfides. The advantages of the present invention are illustrated below by comparing the performance of 3-methylpiperidine, 1,3-dimethylpiperidine, 4-hydroxypiperidine, N-methylpiperidine, 3-(furan-2-yl)piperidine, 2-propanolpiperidine, and 2-ethoxypiperidine with those of traditional solvents ethanolamine and N-methylethanolamine.

[0036] The absorption method is used to remove sulfur from the raw gas. The absorption method purification process is shown in the attached Figure 1The raw gas 3 contacts the absorption liquid 4 entering the absorption tower in the counter-phase in the absorption tower 5 to remove the acidic components and is discharged from the top of the tower as the purified gas 1. The absorption tower rich liquid 2 that has absorbed the acidic components comes out from the bottom of the tower.

[0037] Absorption tower 5 is 1.2 meters high, has 20 theoretical plates, is filled with bulk filler, has a temperature control accuracy of ±0.2°C, uses countercurrent contact for gas-liquid contact, and has an absorption temperature of 40°C. The feed gas flow rate is controlled by a gas flow meter, and the absorption liquid flow rate is controlled by a horizontal flow pump.

[0038] Before the experiment, the tower was washed with deionized water at a flow rate of 20 ml / min for 40 minutes, and then rinsed with absorption solvent at a flow rate of 10 ml / min for 30 minutes. The absorption tower temperature was set to 40°C, and then absorption began. The absorption liquid flow rate was set to 2 ml / min, and the gas flow rate was set according to the gas-liquid ratio. After 40 minutes of absorption, the purified gas was taken for testing and compared with the raw gas content to calculate the removal rate of each component. The calculation method of the removal rate α of each component is as follows:

[0039]

[0040] C1 and C2 represent the concentrations of the corresponding components in the raw gas and purified gas, respectively. H2S and CO2 are detected using gas detection tubes produced by Hebi Huaan Gas Detection Technology Co., Ltd., while COS, methyl mercaptan, and dimethyl sulfide are quantitatively analyzed using a gas chromatograph equipped with an FPD.

[0041] In the following examples, unless otherwise specified, raw materials, reagents or processing techniques are all conventional commercially available products or conventional processing techniques in the art.

[0042] In the following examples, 3-methylpiperidine, 4-hydroxypiperidine, N-methylpiperidine, 4-hydroxypiperidinazine, N-methyldiethanolamine, and ethanolamine were purchased from Shanghai MacLean Biochemical Technology Co., Ltd.

[0043] Example 1

[0044] The reaction rates of piperidine compounds with COS were calculated using Gaussian quantum chemical calculation software using transition state theory and the van't Hoff equation. The reaction rate and equilibrium constant of ethanolamine were set to 1, and the relative rates and relative equilibrium of piperidine compounds were calculated. The relative rate of 3-methylpiperidine was 1.175×10 5 , the relative equilibrium is 142.913; the relative rate of 1,3-dimethylpiperidine is 4.577×10 5 , the relative equilibrium is 25.642; the relative rate of 4-hydroxypiperidine is 3.147×10 4, the relative equilibrium is 24.982; the relative rate of N-methylpiperidine is 1.998×10 4 , the relative equilibrium is 24.297; the relative rate of 3-(furan-2-yl)piperidine is 1.870×10 4 , the relative equilibrium is 33.007; the relative rate of 2-propanol piperidine is 5.160×10 3 , the relative equilibrium is 21.631; the relative rate of 2-ethoxypiperidine is 5.033×10 3 , the relative balance is 20.587.

[0045] Example 2

[0046] The following raw gas composition was used: hydrogen sulfide 5.0 mol%, carbon dioxide 5.0 mol%, carbonyl sulfide 100 mgS / Nm 3 , methyl mercaptan 50mgS / Nm 3 , dimethyl sulfide 50mgS / Nm 3 , and the rest is nitrogen.

[0047] The absorption solution had the following composition (all by mass fraction): 40% 3-methylpiperidine, the remainder water, and the sum of the components was 1. The absorption temperature was 40° C., the absorption pressure was 101.325 kPa, the feed gas flow rate was 40.0 L / h, and the absorption liquid circulation rate was 0.20 L / h.

[0048] The H2S content of the purified gas is less than 0.1ppm, the CO2 content is less than 0.1ppm, and the carbonyl sulfide content is less than 0.1mgS / Nm 3 , methyl mercaptan content 6.8mgS / Nm 3 , methyl sulfide content 10.6mgS / Nm 3 . It meets the national standard of Class I natural gas.

[0049] The H2S removal rate is greater than 99.99%, the CO2 removal rate is greater than 99.99%, the carbonyl sulfide removal rate is greater than 99.9%, the methyl mercaptan removal rate is 86.4%, and the methyl sulfide removal rate is 78.8%.

[0050] Example 3

[0051] The following raw gas composition was used: hydrogen sulfide 5.0 mol%, carbon dioxide 5.0 mol%, carbonyl sulfide 100 mgS / Nm 3 , methyl mercaptan 50mgS / Nm 3 , dimethyl sulfide 50mgS / Nm 3 , and the rest is nitrogen.

[0052] The absorption solution had the following composition (all by mass fraction): 40% 4-hydroxypiperidine, the remainder water, and the sum of the components was 1. The absorption temperature was 40° C., the absorption pressure was 101.325 kPa, the feed gas flow rate was 40.0 L / h, and the absorption liquid circulation rate was 0.20 L / h.

[0053] The H2S content of the purified gas is less than 0.1ppm, the CO2 content is less than 0.1ppm, and the carbonyl sulfide content is less than 0.1mgS / Nm 3 , methyl mercaptan content 5.4mgS / Nm 3 , methyl sulfide content 8.4mgS / Nm 3 . It meets the national standard of Class I natural gas.

[0054] The H2S removal rate is greater than 99.99%, the CO2 removal rate is greater than 99.99%, the carbonyl sulfide removal rate is greater than 99.9%, the methyl mercaptan removal rate is 89.2%, and the methyl sulfide removal rate is 83.2%.

[0055] Example 4

[0056] The following raw gas composition was used: hydrogen sulfide 5.0 mol%, carbon dioxide 5.0 mol%, carbonyl sulfide 100 mgS / Nm 3 , methyl mercaptan 50mgS / Nm 3 , dimethyl sulfide 50mgS / Nm 3 , and the rest is nitrogen.

[0057] The absorption solution had the following composition (all by mass fraction): 40% N-methylpiperidine, the remainder water, the sum of the contents of each component being 1. The absorption temperature was 40° C., the absorption pressure was 101.325 kPa, the feed gas flow rate was 40.0 L / h, and the absorption liquid circulation rate was 0.20 L / h.

[0058] The H2S content of the purified gas is less than 0.1ppm, the CO2 content is less than 0.1ppm, and the carbonyl sulfide content is less than 0.1mgS / Nm 3 , methyl mercaptan content 7.3mgS / Nm 3 , methyl sulfide content 6.9mgS / Nm 3 . It meets the national standard of Class I natural gas.

[0059] The H2S removal rate is greater than 99.99%, the CO2 removal rate is greater than 99.99%, the carbonyl sulfide removal rate is greater than 99.9%, the methyl mercaptan removal rate is 85.4%, and the methyl sulfide removal rate is 86.2%.

[0060] Example 5

[0061] The following raw gas composition was used: hydrogen sulfide 5.0 mol%, carbon dioxide 5.0 mol%, carbonyl sulfide 100 mgS / Nm3 , methyl mercaptan 50mgS / Nm 3 , dimethyl sulfide 50mgS / Nm 3 , and the rest is nitrogen.

[0062] An absorption solution having the following composition (all by mass fraction) was used: 20% 3-methylpiperidine, 20% N-methyldiethanolamine, and the remainder water, with the sum of the components being 1. The absorption temperature was 40°C, the absorption pressure was 101.325 kPa, the feed gas flow rate was 40.0 L / h, and the absorption liquid circulation rate was 0.20 L / h.

[0063] The H2S content of the purified gas is less than 0.1ppm, the CO2 content is less than 0.1ppm, and the carbonyl sulfide content is less than 0.1mgS / Nm 3 , methyl mercaptan content 10.6mgS / Nm 3 , methyl sulfide content 6.7mgS / Nm 3 . It meets the national standard of Class I natural gas.

[0064] The H2S removal rate is greater than 99.99%, the CO2 removal rate is greater than 99.99%, the carbonyl sulfide removal rate is greater than 99.9%, the methyl mercaptan removal rate is 78.8%, and the methyl sulfide removal rate is 86.6%.

[0065] Example 6

[0066] The following raw gas composition was used: hydrogen sulfide 5.0 mol%, carbon dioxide 5.0 mol%, carbonyl sulfide 100 mgS / Nm 3 , methyl mercaptan 50mgS / Nm 3 , dimethyl sulfide 50mgS / Nm 3 , and the rest is nitrogen.

[0067] An absorption solution having the following composition (all by mass fraction) was used: 20% N-methylpiperidine, 20% N-methyldiethanolamine, and the remainder water, with the sum of the components being 1. The absorption temperature was 40°C, the absorption pressure was 101.325 kPa, the feed gas flow rate was 40.0 L / h, and the absorption liquid circulation rate was 0.20 L / h.

[0068] The H2S content of the purified gas is less than 0.1ppm, the CO2 content is less than 0.1ppm, and the carbonyl sulfide content is less than 0.1mgS / Nm 3 , methyl mercaptan content 9.5mgS / Nm 3 , methyl sulfide content 9.3mgS / Nm 3 . It meets the national standard of Class I natural gas.

[0069] The H2S removal rate is greater than 99.99%, the CO2 removal rate is greater than 99.99%, the carbonyl sulfide removal rate is greater than 99.9%, the methyl mercaptan removal rate is 81%, and the methyl sulfide removal rate is 81.4%.

[0070] Example 7

[0071] The following raw gas composition was used: hydrogen sulfide 5.0 mol%, carbon dioxide 5.0 mol%, carbonyl sulfide 100 mgS / Nm 3 , methyl mercaptan 50mgS / Nm 3 , dimethyl sulfide 50mgS / Nm 3 , and the rest is nitrogen.

[0072] An absorption solution having the following composition (all by mass fraction) was used: 20% 4-hydroxypiperidine, 20% N-methyldiethanolamine, and the remainder water, with the sum of the components being 1. The absorption temperature was 40°C, the absorption pressure was 101.325 kPa, the feed gas flow rate was 40.0 L / h, and the absorption liquid circulation rate was 0.20 L / h.

[0073] The H2S content of the purified gas is less than 0.1ppm, the CO2 content is less than 0.1ppm, and the carbonyl sulfide content is less than 0.1mgS / Nm 3 , methyl mercaptan content 8.1mgS / Nm 3 , methyl sulfide content 10.5mgS / Nm 3 . It meets the national standard of Class I natural gas.

[0074] The H2S removal rate is greater than 99.99%, the CO2 removal rate is greater than 99.99%, the carbonyl sulfide removal rate is greater than 99.9%, the methyl mercaptan removal rate is 83.8%, and the methyl sulfide removal rate is 79%.

[0075] Comparative Example 1

[0076] The following raw gas composition was used: hydrogen sulfide 5.0 mol%, carbon dioxide 5.0 mol%, carbonyl sulfide 100 mgS / Nm 3 , methyl mercaptan 50mgS / Nm 3 , dimethyl sulfide 50mgS / Nm 3 , and the rest is nitrogen.

[0077] The absorption solution used had the following composition (all by mass fraction): 40% N-methyldiethanolamine, the remainder water, with the sum of the components being 1. The absorption temperature was 40°C, the absorption pressure was 101.325 kPa, the feed gas flow rate was 40.0 L / h, and the absorption liquid circulation rate was 0.20 L / h.

[0078] The H2S content of the purified gas is less than 0.1ppm, the CO2 content is 2.1mol%, and the carbonyl sulfide content is 63mgS / Nm 3, methyl mercaptan content 43mgS / Nm 3 , methyl sulfide content 41mgS / Nm 3 .

[0079] The H2S removal rate is greater than 99.99%, the CO2 removal rate is 58%, the carbonyl sulfide removal rate is greater than 37%, the methyl mercaptan removal rate is 14%, and the methyl sulfide removal rate is 18%.

[0080] Comparative Example 2

[0081] The following raw gas composition was used: hydrogen sulfide 5.0 mol%, carbon dioxide 5.0 mol%, carbonyl sulfide 100 mgS / Nm 3 , methyl mercaptan 50mgS / Nm 3 , dimethyl sulfide 50mgS / Nm 3 , and the rest is nitrogen.

[0082] The absorption solution used had the following composition (all by mass fraction): 40% ethanolamine, the remainder water, and the sum of the components was 1. The absorption temperature was 40°C, the absorption pressure was 101.325 kPa, the feed gas flow rate was 40.0 L / h, and the absorption liquid circulation rate was 0.20 L / h.

[0083] The H2S content of the purified gas is less than 0.1ppm, the CO2 content is 0.5mol%, and the carbonyl sulfide content is 58mgS / Nm 3 , methyl mercaptan content 48mgS / Nm 3 , methyl sulfide content 44mgS / Nm 3 .

[0084] The H2S removal rate is greater than 99.99%, the CO2 removal rate is 9%, the carbonyl sulfide removal rate is greater than 42%, the methyl mercaptan removal rate is 4%, and the methyl sulfide removal rate is 12%.

[0085] It can be seen from the examples and comparative examples that the piperidine compounds of the present invention have higher organic sulfur solubility and removal efficiency, especially carbonyl sulfide, than existing organic alcohol amine compounds, which helps to meet the desulfurization needs of raw gas with high organic sulfur content and low absorption pressure.

[0086] The above description of the embodiments is intended to facilitate understanding and use of the invention by those skilled in the art. It will be apparent that those skilled in the art can readily make various modifications to these embodiments and apply the general principles described herein to other embodiments without requiring inventive effort. Therefore, the present invention is not limited to the above-described embodiments. Improvements and modifications made by those skilled in the art based on the disclosure of the present invention, without departing from the scope of the present invention, should be within the scope of protection of the present invention.

Claims

1. A method for absorbing and removing sulfides, characterized in that: include: Contacting the sulfide-containing gas to be treated with a solution containing a compound having the following structural formula; R1 is hydrogen or C 1～4 Alkyl substituents, R2, R3 and R4 are independently selected from hydrogen, hydroxyl, C 1～4 At least one of an alkyl, alkoxy, hydroxyalkyl, or heterocyclic substituent; The sulfide is selected from at least one of hydrogen sulfide, COS, CS2, mercaptan, sulfide or disulfide.

2. The method for absorbing and removing sulfides according to claim 1, characterized in that: R1 is one of hydrogen, methyl or ethyl; R2, R3 and R4 are independently selected from one of hydrogen, hydroxyl, ethyl, propyl, butyl, ethanol, propanol, butanol, ethoxy, propoxy, butoxy, ethylamino, propylamino, butylamino, furyl or pyridyl.

3. The method for absorbing and removing sulfides according to claim 1, characterized in that: The compound is selected from at least one of 2-methylpiperidine, 3-methylpiperidine, 1,3-dimethylpiperidine, 4-methylpiperidine, 4-hydroxypiperidine, N-methylpiperidine, 3-(furan-2-yl)piperidine, 2-piperidinylethylamine, 4-methyl-piperidin-1-ylamine, and 3-(piperidin-2-yl)propan-1-ol.

4. The method for absorbing and removing sulfides according to claim 1, characterized in that: In the solution, the mass concentration of the compound is 40-60%.

5. The method for absorbing and removing sulfides according to claim 1, characterized in that: The solution also includes an organic amine; the mass ratio of the compound to the organic amine is 2:3 to 3:

2.

6. The method for absorbing and removing sulfides according to claim 5, characterized in that: The organic amine is selected from at least one of alkylamines, alkylolamines, amides, phosphoramides, benzylamines, or derivatives of the above amine compounds.

7. The method for absorbing and removing sulfides according to claim 6, characterized in that: The organic amine is selected from at least one of monoethanolamine, diethanolamine, diisopropanolamine, diglycolamine and N-methyldiethanolamine.

8. The method for removing sulfide by absorption according to claim 7, characterized in that: The organic amine is N-methyldiethanolamine, the compound is 3-methylpiperidine, and the mass ratio of the N-methyldiethanolamine to the 3-methylpiperidine is 1:

1.

9. The method for removing sulfide by absorption according to claim 5, characterized in that: In the solution, the total mass concentration of the compound and the organic amine is 40-60%.

10. The method for removing sulfide by absorption according to claim 9, characterized in that: In the solution, the total mass concentration of the compound and the organic amine is 40%.

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