Low-energy-consumption diamine compound for desulfurization and decarbonization as well as preparation method and application thereof

Abstract

The invention relates to an application of a diamine compound, the diamine compound has the following molecular structure: in the formula, R1 is at least one of hydroxyl, amido, carbonyl, ester group, sulfydryl or aromatic ring, R2 and R3 are respectively and independently C1-2 alkyl substituent groups, R4 and R5 are C1-4 alkyl or hydroxyalkyl substituent groups, n is 1-5, and n is 1-5; the diamine compound is used for absorbing one or more of carbon dioxide, hydrogen sulfide or organic sulfur. Compared with the prior art, the diamine compound disclosed by the invention can be mixed with other organic amines to prepare a low-energy-consumption desulfurization and decarbonization solvent capable of regulating and controlling reaction heat, and the solvent can be applied to absorption and removal of acidic components such as carbon dioxide, hydrogen sulfide and organic sulfur in petrochemical gases such as natural gas, oilfield associated gas and refinery gas; the regeneration energy consumption can be obviously reduced on the premise of effectively removing carbon dioxide, hydrogen sulfide and carbonyl sulfide.

Description

Technical Field

[0001] The present invention belongs to the technical field of desulfurization and decarbonization in the petrochemical industry, and relates to a diamine compound and a preparation method and application thereof, and in particular to a diamine compound with controllable reaction heat and a use method thereof and a low-energy desulfurization and decarbonization application thereof. Background Art

[0002] Climate change and air pollution pose serious risks to the health of people worldwide and global economic development. Evolving standards for CO2, H2S, and organic sulfur content in acid gases like natural gas and refinery gas are becoming increasingly stringent, necessitating the development of desulfurization and decarbonization technologies that meet these industry demands.

[0003] Among various desulfurization and decarbonization methods, absorption has many advantages, such as large processing capacity, mature and simple process, and adaptability to a wide range of gas compositions. It is currently the most widely used process technology. Various solvents, including organic amines, ionic liquids, deep eutectic solvents, and phase change solvents, have been widely studied as desulfurization and decarbonization solvents. In recent years, new solvents such as ionic liquids, deep eutectic solvents, and phase change solvents have gradually received increasing attention. However, desulfurization and decarbonization technologies based on these new solvents still face many challenges before they can be applied on a large scale in industry. For example, the viscosity of highly acidic gas-loaded solvents increases significantly, and the heat and mass transfer performance decreases significantly. In contrast, amine solvents, including monoethanolamine (MEA), diethanolamine (DEA), N-methyldiethanolamine (MDEA), and diisopropanolamine (DIPA), remain the most widely used desulfurization and decarbonization solvents due to their acceptable absorption performance and mature process.

[0004] However, the absorption process based on alcohol amine solvents faces the challenge of high energy consumption during the regeneration process. In order to solve this problem, researchers have invested a lot of energy in developing new solvents or mixed solvents. The prior art CN117899637A takes into account that the co-absorption of CO2 by the solvent leads to a decrease in the organic sulfur removal rate and an increase in energy consumption, and proposes a low-energy desulfurization and decarbonization solvent and its application, including a composite amine, an ionic liquid and an organic sulfur absorption promoter. The composite amine includes N-methyldiethanolamine and 2-cyclohexylamino-1,3-propanediol. 2-Cyclohexylamino-1,3-propanediol can react with hydrogen sulfide, methyl mercaptan and carbonyl sulfide to increase the removal rate of sulfur compounds, while the cyclohexyl group can hinder the approach of carbon dioxide to the reactive group, and the 1,3-dihydroxypropyl group can provide good water solubility for the sterically hindered amine molecules.

[0005] Prior art CN116110513A proposes a molecular design method and application for triazine desulfurizers. Using Materials Studio molecular simulation software, the method constructs a nucleophilic substitution reaction pathway between triazine liquid desulfurizers and H2S. By comparing and analyzing the energy of the reaction products of triazine molecules with different terminal functional groups and molecular chain structures and H2S, the molecular structure of the triazine liquid desulfurizer is optimized, thereby selecting triazine desulfurizers with high desulfurization capacity and stability.

[0006] Although the desulfurization and decarbonization solvents mentioned in the above patents have a certain removal effect and can reduce regeneration energy consumption when facing specific process requirements, in order to meet the country's continuously promoted carbon capture policy and efficient desulfurization needs, it is necessary to propose a new method that can cope with the removal needs of complex raw material compositions of petrochemical gases such as natural gas, oilfield associated gas, and refinery gas, and can also meet the reduction of regeneration energy consumption under various processes, and achieve high efficiency, economy, and environmental protection technical requirements. Summary of the Invention

[0007] The present invention aims to provide a diamine compound with controllable reaction heat, a method for its use, and low-energy desulfurization and decarbonization applications, addressing the low removal efficiency of existing desulfurization and decarbonization solvents for carbon dioxide (CO2), hydrogen sulfide (H2S), and carbonyl sulfide (COS). By introducing an electron-withdrawing group at the β-carbon atom of one of the amine groups in the diamino functional group, the present invention effectively controls the thermodynamic characteristics of the reaction, reduces the stability of the reaction products, and thereby reduces the reaction enthalpy change of carbon dioxide, hydrogen sulfide, and carbonyl sulfide, thereby improving the absorption efficiency of carbon dioxide, hydrogen sulfide, and carbonyl sulfide.

[0008] The purpose of the present invention can be achieved by the following technical solutions:

[0009] The present invention provides an application of a diamine compound, wherein the diamine compound has the following molecular structure:

[0010]

[0011] In the formula, R1 is an electron-withdrawing group, R2 and R3 are independently C 1～2 alkyl substituent, R4 and R5 are each independently C 1～4 alkyl or hydroxyalkyl substituent, n=1-5;

[0012] The diamine compound is used to absorb one or more of carbon dioxide, hydrogen sulfide or organic sulfur.

[0013] In some specific embodiments, R1 is at least one of a hydroxyl group, an amine group, a carbonyl group, an ester group, a thiol group, or an aromatic ring.

[0014] In some specific embodiments, n=1-3.

[0015] In some specific embodiments, the diamine compound is selected from at least one of bis(dimethylamino)ethyl ether, dimethylaminoethyldimethylaminopropyl ether, 1,3-bis(dimethylamino)-2-propanol, 2-[[2-[2-(dimethylamino)ethoxyethyl]methylamino]-ethanol or 2-[2-(diethylamino)ethoxy]-N,N-dimethylethylamine.

[0016] In some specific embodiments, the diamine compound is mixed with water to prepare an aqueous solution with a mass fraction of 5 to 60% as the absorption solution, preferably, the aqueous solution with a mass fraction of 15 to 50% is prepared for use.

[0017] In some specific embodiments, the diamine compound and the organic amine are mixed in water as an absorption solution for absorbing one or more of carbon dioxide, hydrogen sulfide or organic sulfur.

[0018] In some specific embodiments, the organic amine is selected from one or more of alkylamines and their derivatives, alkylolamines and their derivatives, amides and their derivatives, phosphoramides and their derivatives, benzylamine and its derivatives, or nitrogen-containing heterocyclic aromatic compounds.

[0019] In some specific embodiments, the mixing mass ratio of the diamine compound to the organic amine is (1-3):1.

[0020] In some specific embodiments, the mass fraction of the mixed aqueous solution obtained by mixing the diamine compound and the organic amine in water is 5 to 60%, preferably 15 to 50%.

[0021] In some specific embodiments, the alkyl alcohol amine is selected from one or more of monoethanolamine, piperazine, diethanolamine, diisopropanolamine, diglycolamine or N-methyldiethanolamine.

[0022] In some specific embodiments, the alkyl alcohol amines are piperazine and diisopropanolamine.

[0023] In some specific embodiments, the mass ratio of the diamine compound to piperazine and diisopropanolamine is (1-3):(0.5-1.5):1.

[0024] In some specific embodiments, the mass ratio of the diamine compound to piperazine and diisopropanolamine is 2:1:1.

[0025] The diamine compound with adjustable reaction heat is used to remove carbon dioxide, hydrogen sulfide and carbonyl sulfide from petrochemical gases including natural gas, oilfield associated gas, refinery gas, etc. The natural gas, oilfield associated gas and refinery gas contain up to about 5 (mol)% carbon dioxide, 20 (mol)% hydrogen sulfide and 500mg / Nm 3 Diamine compounds with controllable reaction heat, due to their excellent absorption capacity and low reaction enthalpy, can ensure that the purification effect of carbon dioxide, hydrogen sulfide and carbonyl sulfide in the logistics meets the relevant indicators, while significantly reducing regeneration energy consumption.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The present invention's diamine compounds, which have controllable reaction heat, contain two tertiary amine groups in their molecular structure. Theoretically, they can efficiently capture acidic gases such as carbon dioxide, hydrogen sulfide, and carbonyl sulfide in a stoichiometric ratio of 1:2, significantly improving absorption capacity. By introducing an electron-withdrawing group at the β-carbon atom of one of the amine groups within the diamino functional groups, the present invention can effectively control the reaction thermodynamics and reduce the stability of the reaction products, thereby reducing the reaction enthalpy change of carbon dioxide, hydrogen sulfide, and carbonyl sulfide, and thereby improving the absorption efficiency of carbon dioxide, hydrogen sulfide, and carbonyl sulfide.

[0028] The diamine compounds in this invention can be mixed with other organic amines to create a low-energy desulfurization and decarbonization solvent with controllable reaction heat. This functional solvent exhibits outstanding process adaptability and can be widely used in the purification of various petrochemical gases, including natural gas, associated oilfield gas, and refinery gas. It effectively copes with the complex and variable sulfur and carbon content of feed gases, is not limited to specific process requirements, and exhibits excellent component adaptability. In practical applications, this solvent not only achieves the synergistic removal of multiple acidic impurities in complex feed gases, but also significantly reduces regeneration energy consumption, demonstrating excellent industrial application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a process flow chart of an absorption purification system in the present invention;

[0030] Description of the marks in the figure:

[0031] 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

[0032] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0033] The present invention has discovered a diamine compound with controllable reaction heat, which can not only achieve efficient desulfurization and decarbonization efficiency, but also significantly reduce regeneration energy consumption. The following performance comparison of bis(dimethylamino)ethyl ether, 1,3-bis(dimethylamino)-2-propanol, and the traditional solvent monoethanolamine is used as an example to illustrate the advantages of the present invention.

[0034] The absorption method is used to remove carbon dioxide, hydrogen sulfide and carbonyl sulfide from the raw gas. The absorption method purification process is shown in the attached Figure 1 In absorption tower 11, feed gas 1 undergoes counter-phase contact with the absorption liquid to remove acidic components before being discharged from the top of the tower. Rich liquid 5, which has absorbed the acidic components, exits the bottom of the tower and enters rich liquid flash tank 12 to flash off dissolved hydrocarbons. The flashed rich liquid 6 exchanges heat with regeneration lean liquid in heat exchanger 15 before entering regeneration tower 13 for desorption and regeneration. Acid gas 4 is discharged from the top of regeneration tower 13 and sent to a sulfur recovery unit for sulfur recovery. Regeneration lean liquid is discharged from the bottom of the tower, cooled by heat exchanger 15 and cooler 14, and then returned to absorption tower 11 for recycling.

[0035] The DFT calculation method and content used are as follows: The calculation research objects of absorption capacity and reaction enthalpy change are the nucleophilic reactions of amines with carbon dioxide, hydrogen sulfide and carbonyl sulfide. The reaction rules of the three gases with organic amines are consistent. Carbon dioxide is selected as the research object here because the absorption and regeneration of carbon dioxide is the key to affecting the high energy consumption of solvent regeneration.

[0036] Gaussian 09 quantitative calculation software was used to perform structural optimization, vibrational analysis, and energy calculations on the molecular model. To ensure accuracy and minimize computational cost, vibrational analysis and structural optimization were performed at the B3LYP / 6-31+G(d) level of theory. The zero-point energy (ZPE), enthalpy correction (Hcorr), and Gibbs free energy correction (Gcorr) were calculated. The electronic energy (Ee) was calculated at the M06-2X / def2TZVP level of theory. The ZPE was corrected using a frequency correction factor (k), resulting in a reported value of 0.9829.

[0037] The energy balance formula is Q = C p Δt / θ+Rr H2O +ΔH r , where C p is the specific heat capacity of the solution, Δt is the difference between the regeneration temperature and the absorption temperature, θ is the circulation capacity of the solution, R is the reflux ratio of the regeneration tower, r H2O is the heat of vaporization of water, ΔH r is the reaction enthalpy change of the solvent, and the unit of Q is GJ / tCO2.

[0038] 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.

[0039] The following are more detailed implementation cases, which further illustrate the technical solutions of the present invention and the technical effects that can be obtained.

[0040] 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 field. Bisdimethylaminoethyl ether can be purchased from Sinopharm Chemical Reagent Co., Ltd., and 1,3-bis(dimethylamino)-2-propanol can be purchased from Shanghai Titan Technology Co., Ltd.

[0041] Example 1

[0042] At 25°C, the absorption capacity of bis(dimethylamino)ethyl ether calculated using Gaussian 09 was 1.36 mol CO2 / mol amine, and the absorption capacity of 1,3-bis(dimethylamino)-2-propanol was 1.31 mol CO2 / mol amine.

[0043] At 25°C, the reaction enthalpy changes of bis(dimethylamino)ethyl ether and 1,3-bis(dimethylamino)-2-propanol calculated using Gaussian 09 were 45.70 kJ / mol and 40.09 kJ / mol, respectively.

[0044] Example 2

[0045] The raw gas composition is as follows: H2S content is 5.0 mol%, CO2 content is 15.0 mol%, COS content is 100 mg / Nm 3 , and the rest is N2.

[0046] The absorption solution has the following composition (all in mass fraction): 20% bis(dimethylaminoethyl)ether, 10% piperazine, 10% diisopropanolamine, 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 101.325kPa, the raw gas flow rate is 40.0L / h, and the absorption liquid circulation volume is 0.20L / h. The flash tank temperature is 55°C, the pressure is 101.325kPa, the regeneration tower top temperature is 45°C, the reflux ratio is 3, the tower bottom temperature is 110°C, and the regeneration pressure is 120kPa. The H2S content in the purified gas is less than 5mg / Nm 3 , CO2 content is less than 0.01mol%, COS content is 6.8ppm, and regeneration energy consumption is 2.76GJ / tCO2.

[0047] Example 3

[0048] The raw gas composition is as follows: H2S content is 5.0 mol%, CO2 content is 15.0 mol%, COS content is 100 mg / Nm 3 , and the rest is N2.

[0049] The absorption solution has the following composition (all in mass fraction): 20% 1,3-bis(dimethylamino)-2-propanol, 10% piperazine, 10% diisopropanolamine, and the rest is water. The total content of each component is 1. The absorption temperature is 25°C, the absorption pressure is 101.325kPa, the raw gas flow rate is 40.0L / h, and the absorption liquid circulation volume is 0.20L / h. The flash tank temperature is 55°C, the pressure is 101.325kPa, the regeneration tower top temperature is 45°C, the reflux ratio is 3, the tower bottom temperature is 110°C, and the regeneration pressure is 120kPa. The H2S content in the purified gas is less than 5mg / Nm 3 , CO2 content is less than 0.01mol%, COS content is 8.2ppm, and regeneration energy consumption is 2.72GJ / tCO2.

[0050] Example 4

[0051] The raw gas composition is as follows: H2S content is 5.0 mol%, CO2 content is 15.0 mol%, COS content is 100 mg / Nm 3 , and the rest is N2.

[0052] The absorption solution has the following composition (all in mass fraction): 20% bis(dimethylaminoethyl)ether, 10% piperazine, 10% diisopropanolamine, 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 101.325kPa, the raw gas flow rate is 60.0L / h, and the absorption liquid circulation volume is 0.20L / h. The flash tank temperature is 55°C, the pressure is 101.325kPa, the regeneration tower top temperature is 45°C, the reflux ratio is 3, the tower bottom temperature is 110°C, and the regeneration pressure is 120kPa. The H2S content of the purified gas is less than 5mg / Nm 3 , CO2 content is less than 0.01mol%, COS content is 11.5ppm, and regeneration energy consumption is 2.83GJ / tCO2.

[0053] Example 5

[0054] The raw gas composition is as follows: H2S content is 5.0 mol%, CO2 content is 15.0 mol%, COS content is 100 mg / Nm 3 , and the rest is N2.

[0055] The absorption solution has the following composition (all in mass fraction): 20% 1,3-bis(dimethylamino)-2-propanol, 10% piperazine, 10% diisopropanolamine, and the rest is water. The total content of each component is 1. The absorption temperature is 25°C, the absorption pressure is 101.325kPa, the raw gas flow rate is 60.0L / h, and the absorption liquid circulation volume is 0.20L / h. The flash tank temperature is 55°C, the pressure is 101.325kPa, the regeneration tower top temperature is 45°C, the reflux ratio is 3, the tower bottom temperature is 110°C, and the regeneration pressure is 120kPa. The H2S content in the purified gas is less than 5mg / Nm 3 , CO2 content is less than 0.01mol%, COS content is 13.6ppm, and regeneration energy consumption is 2.78GJ / tCO2.

[0056] Example 6

[0057] The raw gas composition is as follows: H2S content is 5.0 mol%, CO2 content is 15.0 mol%, COS content is 100 mg / Nm 3 , and the rest is N2.

[0058] The absorption solution has the following composition (all in mass fraction): 25% bis(dimethylaminoethyl)ether, 8% piperazine, 7% diisopropanolamine, 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 101.325kPa, the raw gas flow rate is 40.0L / h, and the absorption liquid circulation volume is 0.20L / h. The flash tank temperature is 55°C, the pressure is 101.325kPa, the regeneration tower top temperature is 45°C, the reflux ratio is 3, the tower bottom temperature is 110°C, and the regeneration pressure is 120kPa. The H2S content of the purified gas is less than 5mg / Nm 3 , CO2 content is less than 0.01mol%, COS content is 8.9ppm, and regeneration energy consumption is 2.68GJ / tCO2.

[0059] Example 7

[0060] The raw gas composition is as follows: H2S content is 5.0 mol%, CO2 content is 15.0 mol%, COS content is 100 mg / Nm 3 , and the rest is N2.

[0061] The absorption solution with the following composition (all in mass fraction) is used: 25% 1,3-bis(dimethylamino)-2-propanol, 8% piperazine, 7% diisopropanolamine, and the rest is water. The total content of each component is 1. The absorption temperature is 25°C, the absorption pressure is 101.325kPa, the raw gas flow rate is 40.0L / h, and the absorption liquid circulation volume is 0.20L / h. The flash tank temperature is 55°C and the pressure is 101.325kPa. The regeneration tower top temperature is 45°C, the reflux ratio is 3, the tower bottom temperature is 110°C, and the regeneration pressure is 120kPa. The H2S content in the purified gas is less than 5mg / Nm 3 , CO2 content is less than 0.01mol%, COS content is 9.3ppm, and regeneration energy consumption is 2.61GJ / tCO2.

[0062] Comparative Example 1

[0063] At 25°C, the absorption capacity of monoethanolamine calculated using Gaussian 09 is 0.54 mol CO2 / molamine, and the reaction enthalpy change is 70.85 kJ / mol; the absorption capacity of hexamethylenediamine is 0.83 mol CO2 / molamine, and the reaction enthalpy change is 68.13 kJ / mol.

[0064] Comparative Example 2

[0065] The raw gas composition is as follows: H2S content is 5.0 mol%, CO2 content is 15.0 mol%, COS content is 100 mg / Nm 3 .

[0066] The absorption solution has the following composition (all in mass fraction): 40% monoethanolamine, the rest water, and the sum of the contents of each component is 1. The absorption temperature is 25°C, the absorption pressure is 101.325kPa, the feed gas flow rate is 40.0L / h, and the absorption liquid circulation volume is 0.20L / h. The flash tank temperature is 55°C and the pressure is 101.325kPa. The regeneration tower top temperature is 45°C, the reflux ratio is 3, the tower bottom temperature is 110°C, and the regeneration pressure is 120kPa. The H2S content of the purified gas is less than 5mg / Nm 3 , CO2 content is less than 0.01 mol%, COS content is 33.7 ppm, and regeneration energy consumption is 3.80 GJ / tCO2.

[0067] Comparative Example 3

[0068] The raw gas composition is as follows: H2S content is 5.0 mol%, CO2 content is 15.0 mol%, COS content is 100 mg / Nm 3 .

[0069] The absorption solution has the following composition (all in mass fraction): monoethanolamine 20%, piperazine 10%, diisopropanolamine 10%, 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 101.325kPa, the raw gas flow rate is 40.0L / h, and the absorption liquid circulation volume is 0.20L / h. The flash tank temperature is 55°C and the pressure is 101.325kPa. The regeneration tower top temperature is 45°C, the reflux ratio is 3, the tower bottom temperature is 110°C, and the regeneration pressure is 120kPa. The H2S content of the purified gas is less than 5mg / Nm 3 , CO2 content is less than 0.01mol%, COS content is 16.3ppm, and regeneration energy consumption is 3.52GJ / tCO2.

[0070] Comparative Example 4

[0071] The raw gas composition is as follows: H2S content is 5.0 mol%, CO2 content is 15.0 mol%, COS content is 100 mg / Nm 3 .

[0072] The absorption solution has the following composition (all in mass fraction): 20% hexamethylenediamine, 10% piperazine, 10% diisopropanolamine, and the rest is water, with the sum of the contents of each component being 1. The absorption temperature is 25°C, the absorption pressure is 101.325kPa, the feed gas flow rate is 40.0L / h, and the absorption liquid circulation volume is 0.20L / h. The flash tank temperature is 55°C and the pressure is 101.325kPa. The regeneration tower top temperature is 45°C, the reflux ratio is 3, the tower bottom temperature is 110°C, and the regeneration pressure is 120kPa. The H2S content in the purified gas is less than 5mg / Nm 3 , CO2 content is less than 0.01mol%, COS content is 29.2ppm, and regeneration energy consumption is 3.50GJ / tCO2.

[0073] Comparative Example 5

[0074] The raw gas composition is as follows: H2S content is 5.0 mol%, CO2 content is 15.0 mol%, COS content is 100 mg / Nm 3 .

[0075] The absorption solution used had the following composition (all by mass fraction): 20% bis(dimethylaminoethyl)ether, the remainder water, with the sum of the component contents being 1. The absorption temperature was 25°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. The flash tank temperature was 55°C and the pressure was 101.325 kPa. The regeneration tower top temperature was 45°C, the reflux ratio was 3, the tower bottom temperature was 110°C, and the regeneration pressure was 120 kPa. The purified gas had an H2S content of 1.6 mol%, a CO2 content of 5.3 mol%, and a COS content of 63.9 ppm. The regeneration energy consumption was 2.60 GJ / tCO2.

[0076] Comparative Example 6

[0077] The raw gas composition is as follows: H2S content is 5.0 mol%, CO2 content is 15.0 mol%, COS content is 100 mg / Nm 3 .

[0078] The absorption solution used was composed of the following composition (all percentages by mass): 10% piperazine, the remainder water, with the sum of the component contents equal to 1. The absorption temperature was 25°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. The flash tank temperature was 55°C and the pressure was 101.325 kPa. The regeneration tower top temperature was 45°C, the reflux ratio was 3, the bottom temperature was 110°C, and the regeneration pressure was 120 kPa. The purified gas had an H2S content of 1.2 mol%, a CO2 content of 5.9 mol%, and a COS content of 49.2 ppm. The regeneration energy consumption was 3.58 GJ / tCO2.

[0079] Comparative Example 7

[0080] The raw gas composition is as follows: H2S content is 5.0 mol%, CO2 content is 15.0 mol%, COS content is 100 mg / Nm 3 .

[0081] The absorption solution used had the following composition (all by mass fraction): 10% diisopropanolamine, the remainder water, with the sum of the components being 1. The absorption temperature was 25°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. The flash tank temperature was 55°C and the pressure was 101.325 kPa. The regeneration tower top temperature was 45°C, the reflux ratio was 3, the bottom temperature was 110°C, and the regeneration pressure was 120 kPa. The purified gas had an H2S content of 1.8 mol%, a CO2 content of 5.8 mol%, and a COS content of 19.8 ppm. The regeneration energy consumption was 3.16 GJ / tCO2.

[0082] In summary, this diamine compound possesses excellent component adaptability, enabling the synergistic removal of multiple acidic impurities from complex feed gases, such as natural gas, associated oilfield gas, and refinery gas, while significantly reducing regeneration energy consumption. DFT calculations, energy balance analysis, and experimental evaluation of absorption performance demonstrate that the diamine compound exhibits excellent absorption capacity and desulfurization and decarbonization effectiveness, with significantly superior reaction enthalpy and regeneration energy consumption compared to existing solvent systems, demonstrating promising application prospects.

[0083] 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. An application of a diamine compound, characterized in that, Diamine compounds have the following molecular structure: In the formula, R1 is at least one of hydroxyl, amine, carbonyl, ester, thiol or aromatic ring, R2 and R3 are independently C 1～2 alkyl substituent, R4 and R5 are each independently C 1～4 alkyl or hydroxyalkyl substituent, n=1-5; The diamine compound is used to absorb one or more of carbon dioxide, hydrogen sulfide or organic sulfur.

2. The use of the diamine compound according to claim 1, characterized in that: The diamine compound is selected from at least one of bis(dimethylamino)ethyl ether, dimethylaminoethyldimethylaminopropyl ether, 1,3-bis(dimethylamino)-2-propanol, 2-[[2-[2-(dimethylamino)ethoxyethyl]methylamino]-ethanol or 2-[2-(diethylamino)ethoxy]-N,N-dimethylethylamine.

3. The use of the diamine compound according to claim 1, characterized in that: The diamine compound and the organic amine are mixed in water and used together to absorb one or more of carbon dioxide, hydrogen sulfide or organic sulfur.

4. The use of the diamine compound according to claim 3, characterized in that: The organic amine is selected from one or more of alkylamines and their derivatives, alkylolamines and their derivatives, amides and their derivatives, phosphoramides and their derivatives, benzylamine and its derivatives, or nitrogen-containing heterocyclic aromatic compounds.

5. The use of the diamine compound according to claim 3, characterized in that: The mixing mass ratio of the diamine compound to the organic amine is (1-3):

1.

6. The use of the diamine compound according to claim 5, characterized in that: The mass fraction of the mixed aqueous solution obtained by mixing the diamine compound and the organic amine in water is 5-60%.

7. The use of the diamine compound according to claim 4, characterized in that: The alkyl alcohol amine is selected from one or more of monoethanolamine, piperazine, diethanolamine, diisopropanolamine, diglycolamine or N-methyldiethanolamine.

8. The use of the diamine compound according to claim 7, characterized in that: The alkyl alcohol amines are piperazine and diisopropanolamine.

9. The use of the diamine compound according to claim 8, characterized in that: The mass ratio of the diamine compound to piperazine and diisopropanolamine is (1-3):(0.5-1.5):

1.

10. The use of the diamine compound according to claim 9, characterized in that: The mass ratio of the diamine compound to piperazine and diisopropanolamine is 2:1:1.

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