An alkoxypropylamine compound and its application in organic sulfur absorption and removal

Abstract

The present invention relates to an alkoxypropylamine compound and its application in organic sulfur absorption and removal. The compound has the following structural formula: #imgabs0# wherein R1 is a C1-6 alkyl substituent, and R2 is H or a C1-3 alkyl substituent. Compared with the prior art, the alkoxypropylamine compound of the present invention has a good deep removal effect on various types of sulfides, and the compound has stable chemical properties, is not easy to decompose, has a small bubble point vapor pressure, has little volatilization loss, is weak in alkalinity, and has light corrosion to equipment, and thus has a good industrial application prospect.

Description

Technical Field

[0001] The invention belongs to the technical field of gas desulfurization and purification, and relates to an alkoxypropylamine compound and application thereof in organic sulfur absorption and removal. Background Art

[0002] Sulfides contained in natural gas, oilfield associated gas, refinery gas, blast furnace gas and other logistics include hydrogen sulfide and organic sulfides such as COS, CS2, mercaptan, sulfide, disulfide, etc.; the presence of H2S will not only corrode the transmission pipeline but also seriously endanger the health of users; COS and mercaptan are the main components of organic sulfur contained in natural gas. If they are not removed, on the one hand, they will cause poisoning of catalysts in downstream chemical processes using natural gas as raw materials. On the other hand, COS and low molecular weight mercaptans discharged into the atmosphere without treatment can form SO2, promote photochemical reactions, and bring serious environmental problems. At the same time, these sulfides have an unbearable odor even at extremely low concentration levels. Therefore, before natural gas is transported by pipeline, the acidic components contained, especially sulfides, must be removed to a specific value. For example, the newly promulgated "Natural Gas" standard GB17820-2018 stipulates that H2S≤6mg / Nm in my country's civil first-class natural gas 3 , total sulfur ≤ 20mg / Nm 3 , H2S≤20mg / Nm in Class II natural gas 3 , total sulfur ≤ 100mg / Nm 3 .

[0003] Refinery gas is one of the products of oil refining units. According to different oil refining processes, it can be divided into catalytic dry gas and liquefied gas, coking dry gas and liquefied gas, catalytic cracking liquefied gas, etc. Since crude oil contains sulfur, these gas phase products also contain different forms of sulfides, usually containing organic sulfur such as H2S and COS, mercaptans, and sulfides. Refinery gas can be used as fuel for refinery process heating furnaces and as raw materials for downstream chemical processes. Sulfides in refinery gas will produce SO2 after burning in the heating furnace, which will cause serious air pollution when discharged into the atmosphere. Sulfides in refinery gas will also corrode equipment and pipelines, reduce their service life, and create safety hazards. When used as chemical raw materials, sulfides in refinery gas will also cause poisoning of downstream process catalysts, shorten the operating cycle of process equipment, increase additional production costs, and sulfides will also contaminate downstream products, resulting in substandard product quality. Therefore, before refinery gas is further processed and utilized, the sulfides contained must also be removed to a certain index. The Petroleum Refining Industry Pollutant Emission Standard GB31570-2015 clearly stipulates that the SO2 emission limit of refinery process heating furnaces is 50 mg / m 3 The "Liquefied Petroleum Gas" GB 11174-2011 clearly stipulates that the total sulfur content of commercial liquefied gas shall not exceed 343 mg / m3 , hydrogen sulfide content does not exceed 10mg / m 3 In addition, blast furnace gas is an important fuel, and the sulfides such as hydrogen sulfide and COS contained in it also need to be effectively removed to strictly control the SO2 content of flue gas emitted by the combustion furnace.

[0004] The absorption method using alkanolamine as solvent is an effective method for removing these acidic components. Commonly used alkanolamines include monoethanolamine (MEA), diethanolamine (DEA), methylmonoethanolamine (MMEA), diethylethanolamine (DEEA), triethanolamine (TEA), diisopropanolamine (DIPA), diglycolamine (DGA) and N-methyldiethanolamine (MDEA). With traditional alkanolamine solvents, H2S and CO2 in the raw gas can generally be removed to the required level as long as the device design is reasonable and the process conditions are appropriate. However, the removal efficiency of organic sulfur such as COS and mercaptans varies greatly due to the different properties of the solvents. The removal efficiency of traditional alkanolamine solvents for organic sulfur is relatively low. Among them, the removal rates of MEA and DEA with strong alkalinity for methyl mercaptan, ethyl mercaptan and propyl mercaptan are only about 45%-50%, 20-25% and 0-10% respectively. In addition, since the acidity of H2S and CO2 is stronger than that of organic sulfides such as COS and mercaptans, the preferential dissolution of a large amount of H2S and CO2 components in alcohol amine solvents will further reduce the solubility of organic sulfur components. Therefore, under the condition that acidic oil and natural gas contains high concentrations of H2S and CO2, as well as relatively high concentrations of organic sulfides such as COS and mercaptans, it is usually difficult to effectively remove high concentrations of H2S and CO2 while effectively removing relatively high content of organic sulfides by simply using traditional alcohol amine solvents.

[0005] Although the concentration of H2S and CO2 in refinery gas is at a medium level, the concentration of organic sulfur such as mercaptans is very high. Acidic components such as H2S, CO2 and COS can often be effectively removed by chemical absorption, while the content of organic sulfur such as mercaptans that are mainly removed by physical dissolution is difficult to be effectively reduced by relying solely on alcohol amine solvents. At present, in order to solve the problem of high mercaptan content in refinery liquefied gas, refineries generally adopt a combined process of amine washing and alkali washing in order to reduce the mercaptan content in liquefied gas to within the target range. This process will reintroduce the liquefied gas after amine washing to remove H2S, CO2 and part of the organic sulfur into the alkali washing tower, so that the alkali liquid and the liquefied gas are in countercurrent contact. During this period, the mercaptan reacts chemically with NaOH and is extracted from the liquefied gas into the alkali liquid, thereby reducing the mercaptan content in the liquefied gas and further reducing the total sulfur content of the liquefied gas. Compared with the simple amine washing process, this process has achieved remarkable results in reducing the total sulfur content of liquefied gas, but it also has many disadvantages. The first is the discharge and treatment of waste alkali. Although the alkali solution in this process can be treated in the process by solvent back extraction, the accumulation of sulfur compounds in it cannot be avoided. After a period of cyclic regeneration treatment, the efficiency of the regenerated alkali solution in removing mercaptans from liquefied gas is significantly reduced and has to be replaced. The discharged waste alkali solution and alkali residue contain sulfide and other sulfides, which emit a foul odor. In addition, due to its alkalinity, improper treatment will also cause environmental pollution. In addition, the disulfide contained in the alkali solution during the regeneration process cannot be completely removed by the back extraction solvent. When it returns to the contact tower to contact the liquefied gas, the disulfide is back extracted by the liquefied gas, resulting in the total sulfur removal effect of the liquefied gas not being effectively improved. Alkali washing can only effectively remove thiol organic sulfur, and the removal effect on other organic sulfur is not obvious, and the scope of application is too limited. As the types of organic sulfur components in liquefied gas become more complex and their content increases, the advantages of this process will be further weakened. In addition, the combination of amine washing and alkali washing increases the complexity of the process flow and the cost of equipment investment, operation and maintenance.

[0006] Improving the selective desulfurization performance of solvents is an effective way to solve the desulfurization problems of natural gas, oilfield associated gas, refinery gas, and blast furnace gas. In order to improve the removal efficiency of organic sulfur by alcohol amine solvents, most workers improve the removal effect of organic sulfur by adding an appropriate amount of auxiliary solvent to the solvent based on MDEA or DIPA, in order to further reduce the total sulfur content in the purified petroleum and natural gas to meet the relevant index requirements.

[0007] In patent CN 102051244A, considering the high content of organic sulfur such as COS in highly acidic petroleum and natural gas, in order to effectively remove organic sulfur components such as COS, active components that effectively catalyze COS hydrolysis, chemical absorption and physical dissolution to remove COS and organic sulfides such as mercaptans are specially added in the solvent composition design. The highly efficient purification desulfurizer for highly acidic petroleum and natural gas composed of these active components has good organic sulfur removal performance. While effectively removing high-concentration H2S, it can also efficiently remove high-content organic sulfides, showing obvious advantages in treating high-sulfur content, especially high-organic sulfur content petroleum and natural gas. However, its organic sulfur solubility and removal efficiency still need to be further improved.

[0008] Patent CN102580473A discloses a novel aqueous solution formed by mixing polyamide-amine dendritic compounds with high desulfurization selectivity and alcohol amine as an absorbent, wherein the mass fraction of the polyamide-amine dendritic compounds is 1% to 15%, and the mass fraction of the alcohol amine is 50% to 10%. The absorbent has better H2S removal selectivity and higher organic sulfur removal rate than conventional alcohol amine solvents.

[0009] Patent CN101507891B discloses a liquid composition for removing sulfides from gas, which is composed of an absorbent, an auxiliary agent and a defoamer; wherein the absorbent is composed of a sterically hindered amine and an alkanolamine; the auxiliary agent is one of thiazoles, fatty amines, and phenols or a mixture thereof; the defoamer is siloxane, and the liquid composition can effectively remove organic and inorganic sulfur from the gas at the same time.

[0010] Patent CN105381686A discloses an absorbent solution for absorbing acid gas and a method for absorbing acid gas. Under the premise of ensuring efficient removal of H2S, the main body of the absorption solution is benzylamine and benzylamine derivatives. It is reported that this solvent and method can significantly reduce the vapor pressure of aniline compounds when used, and enhance its removal effect on COS and mercaptans.

[0011] However, most of the above-mentioned disclosed methods use alkyl alcohol amines (N-methyldiethanolamine, triisopropanolamine) as the main solvent, and improve the removal efficiency of organic sulfur on the basis of the original alkyl alcohol amine by preferably using modifiers such as hindered amines. The organic sulfur-containing gas objects that they can treat are relatively fixed, and usually cannot meet the complex and changeable organic sulfur removal requirements in different raw materials.

[0012] In order to meet the increasingly stringent requirements for total sulfur removal, it is necessary to further optimize the solvent components and composition to improve the absorption and solubility performance of different types of organic sulfur and achieve deep removal of various types of sulfides. Summary of the invention

[0013] The purpose of the present invention is to provide an alkoxypropylamine compound and its application in organic sulfur absorption and removal. The alkoxypropylamine compound in the present invention has a good deep removal effect on various types of sulfides, and the compound has stable chemical properties, is not easy to decompose, has a small bubble point vapor pressure, has little volatilization loss, is weak in alkalinity, and has light corrosion to equipment, so it has a good industrial application prospect.

[0014] The purpose of the present invention can be achieved by the following technical solutions:

[0015] An alkoxypropylamine compound has the following structural formula:

[0016]

[0017] In the formula, R1 is a C1-6 alkyl substituent, and R2 is H or a C1-3 alkyl substituent.

[0018] Furthermore, the R1 is a C3-5 alkyl substituent.

[0019] Furthermore, the compound is one or a mixture of 3-propoxypropylamine, 3-isopropoxypropylamine, 3-butoxypropylamine, 3-isobutoxypropylamine or 3-isopentyloxypropylamine.

[0020] An application of an alkoxypropylamine compound comprises using the compound to remove organic sulfur in a gas phase.

[0021] Furthermore, the gas phase includes one of oilfield associated gas, refinery gas or blast furnace gas.

[0022] Furthermore, the organic sulfur includes at least one of hydrogen sulfide, COS, CS2, mercaptan, sulfide or disulfide.

[0023] Furthermore, the compound is prepared into an aqueous solution with a mass fraction of 5 to 60% to serve as an organic sulfur absorbing liquid.

[0024] Furthermore, the compound and the organic amine are mixed at a mass ratio of (1-99):(99-1) to obtain a mixed amine, and then an aqueous solution is prepared with a mass fraction of the mixed amine of 5-75% to serve as an organic sulfur absorbing liquid;

[0025] The organic amine includes at least one of alkylamine, alkylolamine, amide, phosphoramide, benzylamine and its derivatives or nitrogen-containing heterocyclic aromatic compounds.

[0026] Furthermore, the organic amine includes at least one of monoethanolamine, diethanolamine, diisopropanolamine, diglycolamine or N-methyldiethanolamine.

[0027] Furthermore, the mixing mass ratio of the compound to the organic amine is (10-90):(90-10), and the mass fraction of the mixed amine in the organic sulfur absorbing liquid is 15-50%.

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

[0029] 1) The alkoxypropylamine compounds of the present invention The alkoxy group in the alkoxypropylamine compounds increases the electron density on the oxygen atom and the nitrogen atom of the propylamine due to the electron donation effect of the alkane group. The group activity of the primary amine group in the alkoxypropylamine can simultaneously serve as a potential hydrogen bond donor and hydrogen bond acceptor, and can attract and capture organic sulfur molecules such as thiols and thioethers. The strong electronic effect makes the alkoxypropylamine compounds have stronger interactions between organic sulfur molecules. At the same time, the branched structure in which the alkoxy group can exist can capture organic sulfur molecules through van der Waals action. Therefore, at the molecular level, this type of compound can effectively improve the solubility of organic sulfur, thereby achieving a lower level of total sulfur in the purified gas product, meeting the requirements of different raw material sulfide compositions, processing conditions and desulfurization indicators.

[0030] 2) Compared with polyamine compounds, the alkoxypropylamine 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 cyclically used in the absorption-regeneration system; compared with aniline compounds, alkoxypropylamine has better chemical stability, is not easy to decompose and deteriorate, and its aqueous solution is more alkaline and less acidic, which can reduce equipment corrosion.

[0031] Taking 3-butoxypropylamine as an example, the bubble point vapor pressure is 112.4Pa, which is lower than the bubble point vapor pressure of diethylaminopropylamine with a similar boiling point of 204.1Pa, and the evaporation loss of 3-butoxypropylamine is lower; the reported 4-methoxybenzylamine needs to be stored at room temperature away from light and is easily deteriorated in the air, while 3-butoxypropylamine has no special requirements for storage conditions and has better thermal stability and chemical stability; it has been determined that the pH values ​​of 10wt% aqueous solutions of 3-butoxypropylamine, diethylaminopropylamine and 4-methoxybenzylamine are 11.4, 11.5 and 12.0, respectively, and the alkalinity of 3-butoxypropylamine is weaker, causing less corrosion to equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic structural diagram of an experimental device for determining the equilibrium solubility of methyl mercaptan in a desulfurization solvent component in the present invention;

[0033] Figure 1 Description of the mark:

[0034] 1-methane gas cylinder; 2-acid gas cylinder; 3-constant temperature water bath; 4-stainless steel reactor; 5-magnetic stirrer; 6-air pressure test device; 7-water bath temperature control device; 8-needle valve; 9-mechanical stirrer;

[0035] Figure 2 It is a structural schematic diagram of the present invention;

[0036] Figure 2 Description of the mark:

[0037] 1-raw 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-lean and rich liquid heat exchanger; 16-regeneration tower top condenser; 17-regeneration tower bottom reboiler. DETAILED DESCRIPTION

[0038] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0039] An alkoxypropylamine compound has the following structural formula:

[0040]

[0041] In the formula, R1 is a C1-6 alkyl substituent, and R2 is H or a C1-3 alkyl substituent.

[0042] In some specific embodiments, the alkoxypropylamine compound is a mixture of one or more long-chain propylamines with a certain number of carbon atoms in the alkoxy group. Preferably, the R1 position in the alkoxypropylamine compound molecule is an alkoxy group with 3 to 5 carbon atoms, and may be a propylamine with an α-alkyl substituent (R2 position). These compounds have good water solubility and are convenient to prepare as solutions; they have better thermal and chemical stability than benzylamine compounds and are not easy to decompose; they have low bubble point vapor pressure and less volatilization loss than multi-amine compounds; and their aqueous solutions are weakly alkaline and less corrosive than other amine solvents.

[0043] In some specific embodiments, the alkoxypropylamine compound is one or a mixture of 3-propoxypropylamine, 3-isopropoxypropylamine, 3-butoxypropylamine, 3-isobutoxypropylamine or 3-isopentyloxypropylamine; preferably 3-isopropoxypropylamine or 3-isobutoxypropylamine.

[0044] An application of an alkoxypropylamine compound includes using the compound to remove organic sulfur in a gas phase. Specifically, the compound is used to remove organic sulfides in oilfield associated gas, refinery gas or blast furnace gas. The organic sulfide is preferably a mixture of one or more of carbonyl sulfide and mercaptan, sulfide or disulfide with a carbon number of 1 to 4. More preferably, it is hydrogen sulfide, COS, CS2, mercaptan, sulfide or disulfide.

[0045] Among them, natural gas, oilfield associated gas, refinery gas, and blast furnace gas contain up to about 8 (mol)% H2S and about 3000mg (in terms of sulfur) / Nm 3 Organic sulfur. When processing natural gas, oilfield associated gas, refinery gas, blast furnace gas and other logistics, 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 effects in the logistics meet 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.

[0046] In some specific embodiments, the compound is prepared into an aqueous solution with a mass fraction of 5 to 60% to serve as an organic sulfur absorbing liquid.

[0047] In some specific embodiments, the compound is mixed with an organic amine in a mass ratio of (1-99):(99-1) to obtain a mixed amine, and then an aqueous solution is prepared with a mass fraction of 5-75% of the mixed amine to serve as an organic sulfur absorption liquid; wherein the organic amine includes at least one of alkylamines, alkyl alcoholamines, amides, phosphoramides, benzylamines and their derivatives or nitrogen-containing heterocyclic aromatic compounds.

[0048] In some specific embodiments, the organic amine includes at least one of monoethanolamine, diethanolamine, diisopropanolamine, diglycolamine or N-methyldiethanolamine; preferably diisopropanolamine and N-methyldiethanolamine.

[0049] In some specific embodiments, the compound and the organic amine are mixed in a mass ratio of (10-90):(90-10) to form a mixed amine, and in the organic sulfur absorbing liquid, the mass fraction of the mixed amine is 15-50%.

[0050] The invention provides an alkoxypropylamine compound, which can efficiently and selectively purify and remove hydrogen sulfide and various types of organic sulfides such as COS, CS2, mercaptans, sulfides, disulfides, etc., and can effectively reduce the H2S and total sulfur content in the logistics at the same time in the case where the organic sulfur content in raw gas such as natural gas, oil field associated gas, refinery gas, blast furnace gas, etc. is particularly high. After absorption test evaluation, the absorbent of this type of compound has excellent organic sulfur absorption and dissolution capacity and removal efficiency, and has better chemical stability than the benzylamine compounds disclosed in the existing patents, and has a smaller evaporation loss than the disclosed amino compounds, and the aqueous solution thereof is less corrosive.

[0051] The following examples are implemented based on the technical solution of the present invention, and provide detailed implementation methods and specific operation processes, but the protection scope of the present invention is not limited to the following examples.

[0052] The present invention has discovered an alkoxypropylamine compound that can efficiently and selectively purify and remove hydrogen sulfide and organic sulfides such as COS, CS2, mercaptans, sulfides, and disulfides. The following uses 3-isopropoxypropylamine and 3-butoxypropylamine as examples to compare the performance with the traditional solvent N-methyldiethanolamine to illustrate the advantages of the present invention:

[0053] The experimental device for determining the equilibrium solubility of methyl mercaptan in the desulfurization solvent components is shown in the attached figure. Figure 1 As shown, it includes a stainless steel reactor 4, a constant temperature water bath 3 arranged outside the stainless steel reactor 4, a water bath temperature control device 7 electrically connected to the constant temperature water bath 3, a magnetic stirrer 5 arranged at the bottom of the constant temperature water bath 3 and adapted to the magnet in the stainless steel reactor 4, a methane gas cylinder 1 and an acid gas cylinder 2 connected to the stainless steel reactor 4, a mechanical stirrer 9 and an air pressure testing device 6 arranged on the stainless steel reactor 4, a vacuum tube arranged between the vacuum pump and the stainless steel reactor 4, an absorption liquid injection pipe arranged between the organic sulfur absorption liquid storage tank and the stainless steel reactor 4, and needle valves 8 respectively arranged on the vacuum tube and the absorption liquid injection pipe.

[0054] Among them, the volume of the stainless steel reactor 4 is 250mL, and the temperature control accuracy is ±0.2℃; the methane gas cylinder 1 is filled with pure methane gas, and the acid gas cylinder 2 is filled with pure gaseous methyl mercaptan. Before the experiment, the pressure is tested with nitrogen, and then 50-100mL of the desulfurization solvent component to be tested is added to the equilibrium reactor. After sealing, the nitrogen in the reactor is fully replaced with methane. Turn on the constant temperature water bath and adjust it to the temperature required for the experiment. After the temperature rises to the set value, a certain partial pressure of methyl mercaptan is filled in. The total pressure of the system is maintained by methane, and the gas-liquid dual drive stirring is turned on. After the system reaches each equilibrium point, trace samples are taken to analyze the concentration of methyl mercaptan in the gas and liquid phases. According to the gas-liquid equilibrium relationship H=P e / X eHenry's constant was calculated as a measure of the solvent's ability to dissolve methyl mercaptan.

[0055] The absorption method is used to remove sulfur from the raw gas. The absorption method purification process is shown in the attached Figure 2 The raw gas 1 is discharged from the top of the tower after the acidic components are removed by counter-phase contact with the absorption liquid in the absorption tower 11. The rich liquid 5 that has absorbed the acidic components comes out from the bottom of the tower and enters the rich liquid flash tank 12 to flash out the dissolved hydrocarbons. The rich liquid 6 after flashing exchanges heat with the regeneration lean liquid in the heat exchanger 15, and then enters the regeneration tower 13 for desorption and regeneration. The acid gas 4 is discharged from the top of the regeneration tower and sent to the sulfur recovery device to recover sulfur. The regeneration lean liquid is discharged from the bottom of the tower, cooled by the heat exchanger 15 and the cooler 14, and then returns to the absorption tower 11 for recycling.

[0056] The specific raw gas composition and absorption solution composition are as follows:

[0057] Example 1

[0058] At 30°C, the Henry coefficient of the dissolution of methyl mercaptan in 3-isopropoxypropylamine is 82.14 kPa; at 40°C, the Henry coefficient of the dissolution of methyl mercaptan in 3-isopropoxypropylamine is 213.06 kPa; at 50°C, the Henry coefficient of the dissolution of methyl mercaptan in 3-isopropoxypropylamine is 367.29 kPa.

[0059] At 30°C, the Henry coefficient of the dissolution of methyl mercaptan in 3-butoxypropylamine is 104.7 kPa; at 40°C, the Henry coefficient of the dissolution of methyl mercaptan in 3-butoxypropylamine is 290.0 kPa; at 50°C, the Henry coefficient of the dissolution of methyl mercaptan in 3-butoxypropylamine is 395.6 kPa.

[0060] Example 2

[0061] At 30°C, the Henry constants of methyl mercaptan in 3-isopropoxypropylamine calculated using COSMO-RS theory are 133.9 kPa, dimethyl sulfide in 3-isopropoxypropylamine is 92.51 kPa, COS in 3-isopropoxypropylamine is 1827 kPa, and CS2 in 3-isopropoxypropylamine is 356.2 kPa. Under the conditions of 50:1 gas-liquid ratio and normal pressure, 3-isopropoxypropylamine was used to treat 3000 mg / Nm 3 (All contents are calculated as S, the same below) The removal rates of methyl mercaptan, dimethyl sulfide, COS and CS2 in the organic sulfur-containing natural gas after reaching dissolution equilibrium are 77.1%, 82.1%, 82.7% and 81.7% respectively.

[0062] At 30°C, the Henry constants of methyl mercaptan in 3-butoxypropylamine calculated using COSMO-RS theory are 160.9 kPa, dimethyl sulfide in 3-butoxypropylamine is 106.5 kPa, COS in 3-butoxypropylamine is 1975 kPa, and CS2 in 3-butoxypropylamine is 406.7 kPa. Under the conditions of 50:1 gas-liquid ratio and normal pressure, 3-butoxypropylamine was used to treat 3000 mg / Nm 3 (All contents are calculated as S, the same below) The removal rates of methyl mercaptan, dimethyl sulfide, COS and CS2 in the organic sulfur-containing natural gas after reaching dissolution equilibrium are 76.3%, 79.7%, 81.2% and 81.0% respectively.

[0063] Example 3

[0064] The raw gas composition is as follows: total organic sulfur content 2500mg / Nm 3 (of which COS 500mg / Nm 3 , Methyl mercaptan 1000mg / Nm 3 , Ethyl mercaptan 500mg / Nm 3 , dimethyl sulfide 500mg / Nm 3 ), H2S content is 5.0 mol%, CO2 content is 5.0 mol%.

[0065] The absorption solution has the following composition (all in mass fraction): 40% 3-butoxypropylamine and the rest water, the sum of the contents of each component is 1. The absorption temperature is 40°C, the absorption pressure is 101.325 kPa, the raw gas flow rate is 60.0 L / h, and the absorption liquid circulation volume is 0.20 L / h. The H2S content of the purified gas is less than 5 mg / Nm 3 , CO2 content is less than 100ppm(v), methyl mercaptan and COS content are 0, and the total organic sulfur removal rate is 88.27%.

[0066] Example 4

[0067] The raw gas composition is as follows: total organic sulfur content 2500mg / Nm 3 (of which COS 500mg / Nm 3 , Methyl mercaptan 1000mg / Nm 3 , Ethyl mercaptan 500mg / Nm 3 , dimethyl sulfide 500mg / Nm 3 ), H2S content is 5.0 mol%, CO2 content is 5.0 mol%.

[0068] The absorption solution has the following composition (all in mass fraction): 12% 3-isopropoxypropylamine, 28% N-methyldiethanolamine, and the rest is water, and the sum of the contents of each component is 1. The absorption temperature is 25°C, the absorption pressure is 101.325 kPa, the raw gas flow rate is 60.0 L / h, and the absorption liquid circulation volume is 0.20 L / h. The H2S content of the purified gas is less than 1 mg / Nm 3 , CO2 content is less than 150ppm (v), methyl mercaptan and COS content are 0, and the total organic sulfur removal rate is 89.15%.

[0069] Example 5

[0070] The raw gas composition is as follows: total organic sulfur content 2500mg / Nm 3 (of which COS 500mg / Nm 3 , Methyl mercaptan 1000mg / Nm 3 , Ethyl mercaptan 500mg / Nm 3 , dimethyl sulfide 500mg / Nm 3 ), H2S content is 5.0 mol%, CO2 content is 5.0 mol%.

[0071] The absorption solution has the following composition (all in mass fraction): 12% 3-butoxypropylamine, 28% N-methyldiethanolamine, and the rest is water, and the sum of the contents of each component is 1. The absorption temperature is 40°C, the absorption pressure is 101.325 kPa, the raw gas flow rate is 60.0 L / h, and the absorption liquid circulation volume is 0.20 L / h. The H2S content of the purified gas is less than 1 mg / Nm 3 , CO2 content is less than 1000ppm (v), methyl mercaptan and COS content are 0, and the total organic sulfur removal rate is 88.33%.

[0072] Example 6

[0073] The following raw gas composition is used: total organic sulfur content 4859mg / Nm 3 (of which COS 714.5mg / Nm 3 , Methyl mercaptan 2143mg / Nm 3 , Ethyl mercaptan 714.5mg / Nm 3 , Propanethiol 429mg / Nm 3 , dimethyl disulfide 858mg / Nm 3 ), H2S content is 2000mg / Nm 3 .

[0074] The absorption solution has the following composition (all in mass fraction): 12% 3-isopropoxypropylamine, 28% N-methyldiethanolamine, and the rest is water, and the sum of the contents of each component is 1. The absorption temperature is 40°C, the absorption pressure is 101.325 kPa, the raw gas flow rate is 60.0 L / h, and the absorption liquid circulation volume is 0.30 L / h. The H2S content of the purified gas is less than 1 mg / Nm 3 , methyl mercaptan content is less than 100mg / Nm 3 , COS content is less than 50mg / Nm 3 The total organic sulfur removal rate was 82.3%.

[0075] Example 7

[0076] The following raw gas composition is used: total organic sulfur content 4859mg / Nm 3 (of which COS 714.5mg / Nm 3 , Methyl mercaptan 2143mg / Nm 3 , Ethyl mercaptan 714.5mg / Nm 3 , Propanethiol 429mg / Nm 3 , dimethyl disulfide 858mg / Nm 3 ), H2S content is 2000mg / Nm 3 .

[0077] The absorption solution has the following composition (all in mass fraction): 12% 3-butoxypropylamine, 28% N-methyldiethanolamine, and the rest is water, and the sum of the contents of each component is 1. The absorption temperature is 40°C, the absorption pressure is 101.325 kPa, the raw gas flow rate is 60.0 L / h, and the absorption liquid circulation volume is 0.30 L / h. The H2S content of the purified gas is less than 1 mg / Nm 3 , methyl mercaptan content is less than 150mg / Nm 3 , COS content is less than 80mg / Nm 3 The total organic sulfur removal rate was 79.47%.

[0078] Comparative Example 1

[0079] At 30°C, the Henry constant of methyl mercaptan in N-methyldiethanolamine calculated using COSMO-RS theory is 398.6 kPa, the Henry constant of dimethyl sulfide in N-methyldiethanolamine is 309.7 kPa, the Henry constant of COS in N-methyldiethanolamine is 5523 kPa, and the Henry constant of CS2 in N-methyldiethanolamine is 1182 kPa.

[0080] Comparative Example 2

[0081] The raw gas composition is as follows: total organic sulfur content 2500mg / Nm 3(of which COS 500mg / Nm 3 , Methyl mercaptan 1000mg / Nm 3 , Ethyl mercaptan 500mg / Nm 3 , dimethyl sulfide 500mg / Nm 3 ), H2S content is 5.0 mol%, CO2 content is 5.0 mol%.

[0082] The absorption solution with the following composition (all in mass fraction) was used: 40% N-methyldiethanolamine, the rest was water, and the sum of the contents of each component was 1. The absorption temperature was 40°C, the absorption pressure was 101.325 kPa, the raw gas flow rate was 60.0 L / h, and the absorption liquid circulation volume was 0.20 L / h. The H2S content of the purified gas was 0, the CO2 content was less than 3%, the removal rates of methyl mercaptan and COS were less than 20%, and the total organic sulfur removal rate was 28.10%.

[0083] It can be seen from the embodiments and comparative examples that the alkoxypropylamine compounds of the present invention have higher organic sulfur solubility and removal efficiency 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.

[0084] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and 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. An application of an alkoxypropylamine compound, characterized in that: The compound is one or a mixture of 3-propoxypropylamine, 3-isopropoxypropylamine, 3-butoxypropylamine, 3-isobutoxypropylamine or 3-isopentyloxypropylamine; The compound removes organic sulfur in the gas phase; The gas phase includes one of oilfield associated gas, refinery gas or blast furnace gas; The organic sulfur includes at least one of hydrogen sulfide, COS, CS2, mercaptan, sulfide or disulfide; The compound is prepared into an aqueous solution with a mass fraction of 5-60% to serve as an organic sulfur absorbing liquid.

2. The use of an alkoxypropylamine compound according to claim 1, characterized in that: The compound and the organic amine are mixed in a mass ratio of (1-99):(99-1) to obtain a mixed amine, and then an aqueous solution is prepared with a mass fraction of the mixed amine of 5-75% to serve as an organic sulfur absorption liquid; The organic amine includes at least one of alkylamine, alkylolamine, amide, phosphoramide, benzylamine and its derivatives or nitrogen-containing heterocyclic aromatic compounds.

3. The use of an alkoxypropylamine compound according to claim 2, characterized in that: The organic amine includes at least one of monoethanolamine, diethanolamine, diisopropanolamine, diglycolamine or N-methyldiethanolamine.

4. The use of an alkoxypropylamine compound according to claim 3, characterized in that: The mass ratio of the compound to the organic amine is (10-90):(90-10), and the mass fraction of the mixed amine in the organic sulfur absorption liquid is 15-50%.

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