Composite solution capable of selectively removing carbonyl sulfide in airflow and application of composite solution

Abstract

The invention belongs to the technical field of gas desulfurization and purification, and relates to a composite solution capable of selectively removing carbonyl sulfide in gas flow and application of the composite solution, the composite solution comprises an amide compound, alkyl alcohol amine and a solvent, and the mass ratio of the amide compound to the alkyl alcohol amine is 2: 3-3: 2; the structural formula of the amide compound is as follows: # imgabs0 #, wherein R1 is an alkane branched chain of which the carbon number is greater than or equal to 2; r2 is an alkane branched chain with an element O or N; and R3 is a substituent group with an aromatic structure. The composite solution is used for selectively removing carbonyl sulfide in a gas flow containing carbon dioxide. Compared with the prior art, the composite solution disclosed by the invention can be used for inhibiting the absorption of carbon dioxide while realizing efficient removal of carbonyl sulfide, so that the regeneration energy consumption is greatly reduced, and deep desulfurization requirements under special occasions can be met.

Description

Technical Field

[0001] The present invention belongs to the technical field of gas desulfurization and purification, and relates to a composite solution capable of selectively removing carbonyl sulfide in a gas stream and its application. Background Art

[0002] Sulfides contained in natural gas, associated oilfield gas, refinery gas and other logistics include hydrogen sulfide, carbonyl sulfide, and organic sulfides such as carbon disulfide; hydrogen sulfide not only corrodes downstream equipment, but also seriously endangers the health of operators; carbonyl sulfide not only has toxicity and can harm human health, groundwater, and organisms, but may also react with oxygen in the atmosphere to generate harmful substances such as ozone and sulfur dioxide. The "Opinions on Promoting the Implementation of Ultra-Low Emissions in the Iron and Steel Industry" clearly requires that the hourly average emission concentrations of particulate matter, SO2, and NO x in the flue gas of blast furnace hot stoves shall not be higher than 10, 50, and 200 mg / Nm 3 respectively, and proposes to "strengthen source control, and fine desulfurization should be implemented for blast furnace gas and coke oven gas". According to the emission requirements, the total sulfur content in blast furnace gas, coke oven gas, and converter gas needs to be reduced to ≤20 mg / Nm 3 .

[0003] Compared with hydrogen sulfide, the efficient removal of carbonyl sulfide faces significant challenges, mainly due to the dual limitations of its solubility and reactivity. How to efficiently remove carbonyl sulfide has become an urgent problem to be solved in the gas purification process. At present, in the process of source treatment, there are mainly hydrolysis methods, adsorption methods, absorption methods, etc. The hydrolysis method mainly hydrolyzes carbonyl sulfide in the gas into hydrogen sulfide and carbon dioxide by using a catalyst, and then hydrogen sulfide is removed by methods such as alkali washing, oxidation, or adsorption to achieve the purpose of fine desulfurization. However, the operation is complex, the equipment energy consumption is high, and the water consumption is large. The adsorption method uses active adsorption materials to adsorb inorganic sulfur and organic sulfur therein to achieve the purpose of desulfurization. This method has high requirements for operating conditions and high energy consumption. The absorption method uses chemical solvents or physical solvents, mainly alkyl alkanolamines, including monoethanolamine (MEA), diethanolamine (DEA), methylmonoethanolamine (MMEA), diethylethanolamine (DEEA), triethanolamine (TEA), diisopropanolamine (DIPA), diglycolamine (DGA), and N-methyldiethanolamine (MDEA), etc., to absorb hydrogen sulfide and carbonyl sulfide through chemical reactions. However, alkanolamines have a good absorption effect on hydrogen sulfide and a poor effect on carbonyl sulfide. Physical solvents absorb hydrogen sulfide and carbonyl sulfide through physical dissolution, but have high requirements for operating conditions. Although there have been research reports on solvents that can significantly improve the removal efficiency of carbonyl sulfide, since carbonyl sulfide is very similar in structure to carbon dioxide and carbon dioxide has higher reactivity, these solvents will preferentially absorb carbon dioxide while absorbing carbonyl sulfide. While maintaining the removal efficiency of carbonyl sulfide, the solvent circulation volume and regeneration energy consumption are very high, increasing the desulfurization cost.

[0004] Patent CN114250088A, considering that the absorption effect of traditional alkanolamine solvents on carbonyl sulfide is not good, in order to effectively remove carbonyl sulfide, provides a composite solvent for removing carbonyl sulfide in blast furnace gas. This composite solvent can effectively promote the reaction of alkanolamine compounds to remove organic sulfur, especially promote the removal of carbonyl sulfide by alkanolamine compounds, and its removal rate of carbonyl sulfide can be as high as over 90%.

[0005] Patent CN116478739A, aiming at the deficiencies of the existing gas purification process, proposes a method for decarbonization and desulfurization of blast furnace gas in coordination. Decarbonization is carried out first before fine desulfurization, and hydrogen sulfide is also removed at the same time. The rich liquid after decarbonization can be regenerated; then it passes through an organic sulfur hydrolysis tower to hydrolyze carbonyl sulfide into hydrogen sulfide, which is then absorbed by an adsorption tower to achieve the purpose of fine desulfurization, and a waste heat recovery device is set up to reduce the operating cost while improving the desulfurization effect.

[0006] Patent CN112011372A proposes a blast furnace gas desulfurization circulation system based on ultraviolet light. The blast furnace gas first passes through an ultraviolet photolysis oxygen device to oxidize the blast furnace gas and obtain sulfur oxides; subsequently, the sulfur oxides are absorbed by an organic solvent to achieve the purpose of desulfurization.

[0007] In summary, it is urgent to develop a new solvent with good carbonyl sulfide removal effect and low regeneration energy consumption. Summary of the Invention

[0008] The purpose of the present invention is to provide a composite solution capable of selectively removing carbonyl sulfide in a gas stream and its application. By compounding an amide compound with an alkyl alkanolamine, it promotes the hydrolysis of carbonyl sulfide or the reaction of carbonyl sulfide with primary and secondary amines, and inhibits the reaction of carbon dioxide with primary and secondary amines, thereby increasing the reaction rate difference between carbonyl sulfide, carbon dioxide and the solution, and realizing the preferential removal of carbonyl sulfide in the coexistence of carbon dioxide. Compared with the publicly disclosed gas desulfurization technologies, the composite solution of the present invention can achieve efficient removal of carbonyl sulfide while inhibiting the absorption of carbon dioxide, thus greatly reducing the regeneration energy consumption and meeting the deep desulfurization requirements in special occasions.

[0009] The purpose of the present invention can be achieved by the following technical solutions:

[0010] The first aspect of the present invention provides a composite solution, comprising an amide compound and an alkyl alkanolamine in a mass ratio of 2:3 to 3:2, and a solvent;

[0011] The structural formula of the amide compound is as follows

[0012]

[0013] In the formula, R1 is an alkane branched chain with a carbon number greater than or equal to 2;

[0014] R2 is an alkane side chain with O or N element;

[0015] R3 is a substituent with an aromatic structure.

[0016] In some preferred embodiments, R2 is a hydrocarbon side chain with a hydroxyl group, a primary amino group, a secondary amino group or an ether group, and R3 is an aromatic substituent such as a benzene ring, pyridine, thiophene or furan.

[0017] In some specific embodiments, the amide compound is one or a combination of two of phenylacetamide and phenylpropionamide.

[0018] In some preferred embodiments, the physical and chemical properties of the amide compound should meet the requirements of industrial solvents, including melting point, boiling point, stability, toxicity, etc. Generally, the melting point is required to be <40 °C, the boiling point is >150 °C, it has good water solubility, good chemical stability and low toxicity.

[0019] In some more preferred embodiments, the amide compound is selected from at least one of N-ethyl-2-methylamino-2-phenylacetamide, N-ethyl-2-hydroxymethyl-2-phenylacetamide, and N-isopropyl-3-amino-3-hydroxy-2-phenylpropionamide.

[0020] In some specific embodiments, the alkyl alkanolamine is selected from at least one of ethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine or diisopropanolamine.

[0021] In some specific embodiments, the solvent is water.

[0022] In some specific embodiments, the composite solution further includes an inhibitor and a regulator;

[0023] The inhibitor is used to assist in reducing the carbon dioxide absorption rate, preferably polypropylene glycol ether, and the dosage is ≤3 wt% of the total dosage of the amide compound and the alkyl alkanolamine;

[0024] The regulator is used to adjust the surface tension and hydrodynamic properties of the solvent, and promote the absorption mass transfer of carbonyl sulfide by the solvent. Preferably, it is polysiloxane, and the dosage is ≤3 wt% of the total dosage of the amide compound and the alkyl alkanolamine.

[0025] In some preferred embodiments, the dosage of the inhibitor is 0.01-0.3 wt% of the total dosage of the amide compound and the alkyl alkanolamine.

[0026] In some preferred embodiments, the dosage of the regulator is 0.01-0.3 wt% of the total dosage of the amide compound and the alkyl alkanolamine.

[0027] In some specific embodiments, the preparation method of the composite solution includes: first mixing the amide compound with alkyl alkanolamine, adding an inhibitor and a regulator, and then mixing with water to prepare an aqueous solution as an absorption solution.

[0028] In some specific embodiments, the total mass concentration of the amide compound, alkyl alkanolamine, inhibitor, and regulator in the composite solution is 5-75%.

[0029] In some preferred embodiments, the total mass concentration of the amide compound, alkyl alkanolamine, inhibitor, and regulator in the composite solution is 30-50%.

[0030] In some preferred embodiments, the preparation method of the composite solution includes: mixing the amide compound with alkyl alkanolamine first, adding an inhibitor and a regulator, and then mixing with water to prepare an aqueous solution as an absorption solution.

[0031] The second aspect of the present invention provides an application of the composite solution as described above, including using the composite solution for selectively removing carbonyl sulfide in a carbon dioxide-containing gas stream.

[0032] In some specific embodiments, while the composite solution selectively removes hydrogen sulfide in logistics such as natural gas, associated oilfield gas, and refinery gas, it can efficiently and selectively remove carbonyl sulfide.

[0033] In some specific embodiments, in the carbon dioxide-containing gas stream, the content of carbonyl sulfide is 95-280 mg / Nm 3 .

[0034] In some specific embodiments, in the carbon dioxide-containing gas stream, the content of carbon dioxide is 1.5-25 mol%.

[0035] In some specific embodiments, in the carbon dioxide-containing gas stream, the content of hydrogen sulfide is 4.5-55 mol%.

[0036] In some specific embodiments, in the carbon dioxide-containing gas stream, the content of methanethiol is 650-700 mg / Nm 3 .

[0037] In some specific embodiments, the used removal system includes:

[0038] An absorption tower for selectively removing carbonyl sulfide in the raw gas containing carbon dioxide and carbonyl sulfide through the composite solution; the purified gas obtained is discharged from the top of the tower, and the rich liquid discharged from the absorption tower is discharged from the bottom of the tower;

[0039] Rich liquid flash tank, used for flashing the rich liquid discharged from the absorption tower, and the flashed gas is rich in hydrocarbons that are easy to dissolve;

[0040] Regeneration tower, used for rectifying the rich liquid discharged from the flash tank, and the acidic gas rich in carbonyl sulfide is discharged from the top of the tower; the regenerated lean liquid is discharged from the bottom of the tower, and after heat exchange with the rich liquid discharged from the flash tank, it is used as the absorption liquid and circulated to the absorption tower.

[0041] As Figure 4 shown, the specific mechanism of the present invention is: (1) According to the organic sulfur removal principle that "carbonyl sulfide (COS) can react with primary and secondary amines to form zwitterions; it can also undergo base-catalyzed hydrolysis reaction to generate hydrogen sulfide and carbon dioxide", it is determined that the absorption of carbonyl sulfide should be achieved through reaction with primary and secondary amines or base-catalyzed hydrolysis reaction.

[0045] (2) According to the carbon dioxide removal principle that "carbon dioxide (CO2) can be physically absorbed and dissolved in a physical solvent; it can also react with primary and secondary amines to form zwitterions". It is determined that the absorption of carbon dioxide should be achieved through reaction with primary and secondary amines or dissolution in a physical solvent.

[0046] (3) According to the reaction activity that "carbon dioxide has a higher acidity than carbonyl sulfide and reacts faster with alkanolamines", the path for selective removal of COS / CO2 is determined. Carbonyl sulfide and carbon dioxide cannot be absorbed through the same reaction path and need to be absorbed through different reaction paths.

[0047] (4) According to the principle that "adding an active substance affects the reaction rate of different reactions", the regulation mechanism for selective removal of COS / CO2 is determined. By adding an amide compound, the hydrolysis of carbonyl sulfide or the reaction of carbonyl sulfide with primary and secondary amines is promoted, and the reaction of carbon dioxide with primary and secondary amines is inhibited, thereby increasing the difference in reaction rates.

[0048] According to the mechanism of the COS / CO2 absorption selectivity regulation method designed above, within a limited reaction time, carbonyl sulfide is reacted completely as much as possible, and the reaction of carbon dioxide is reduced to achieve selective absorption of carbonyl sulfide.

[0049] Compared with the prior art, the present invention has the following characteristics:

[0050] The present invention mixes an amide compound with an alkyl alkanolamine to increase the difference in reaction rates between carbonyl sulfide and carbon dioxide, so as to preferentially and efficiently remove trace carbonyl sulfide (95 - 280 mg / Nm 3Meanwhile, it inhibits the absorption of carbon dioxide. Specifically, it can control the carbon dioxide removal rate at about 50% under the condition that the carbonyl sulfide removal rate is close to 100%; or it can control the carbon dioxide removal rate below 5% and achieve a carbonyl sulfide removal rate of more than 80%. It is applicable to the deep desulfurization in special occasions such as natural gas, associated gas in oil fields, and refinery gas.

[0051] The present invention has significant advantages such as simple operation and low regeneration energy consumption. While meeting the requirements for carbonyl sulfide removal, it can reduce the energy cost of enterprises. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 It is a schematic flow diagram of the absorption and purification process; In the figure: 1 - raw gas; 2 - purified gas; 3 - flash gas; 4 - sour gas; 5 - rich liquid from the absorption tower; 6 - rich liquid from the flash tank; 7 - rich liquid from the heat exchanger; 8 - lean liquid from the regeneration tower; 9 - lean liquid from the heat exchanger; 10 - lean liquid from the cooler; 11 - absorption tower; 12 - rich liquid flash tank; 13 - regeneration tower; 14 - lean liquid cooler for regeneration; 15 - heat exchanger for rich and lean liquids; 16 - condenser at the top of the regeneration tower; 17 - reboiler at the bottom of the regeneration tower.

[0053] Figure 2 It is the pKa results of the aqueous solutions of N-ethyl-2-methylamino-2-phenylacetamide (Compound 1), N-ethyl-2-hydroxymethyl-2-phenylacetamide (Compound 2), and N-isopropyl-3-amino-3-hydroxy-2-phenylpropanamide (Compound 3) calculated using the COSMO thermX software.

[0054] Figure 3 It is the comparison result of the reaction rate constants of Compound 1, Compound 2, and Compound 3 with COS / CO2 calculated using the Gaussian 16W software.

[0055] Figure 4 It is the regulation mechanism diagram for the selective desulfurization achieved by the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0056] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0057] The present invention constructs a composite solution with amide compounds and alkyl alkanolamines as the main components. Based on this composite solution, a new regulation method for selective removal of COS / CO2 in gas is designed, which can effectively remove carbonyl sulfide and inhibit the absorption of carbon dioxide. The amide compounds used are exemplified by N-ethyl-2-methylamino-2-phenylacetamide, N-ethyl-2-hydroxymethyl-2-phenylacetamide, and N-isopropyl-3-amino-3-hydroxy-2-phenylpropanamide.

[0058] Test the alkalinity of the aqueous solutions of three compounds. Based on the COSMO-RS theory, use the COSMO thermX software to calculate the pKa of the aqueous solutions of different compounds, and compare them with monoethanolamine (MEA) and diethanolamine (DEA). Use the Gaussian16W software to calculate the reaction rate constants of the reactions of the molecules of the three compounds with COS / CO2 respectively according to the transition state theory at the theoretical level of B3LYP / 6-311+G*, and compare them with monoethanolamine (MEA) and diethanolamine (DEA).

[0059] N-ethyl-2-methylamino-2-phenylacetamide, the structural formula is as follows:

[0060]

[0061] N-ethyl-2-hydroxymethyl-2-phenylacetamide, the structural formula is as follows:

[0062]

[0063] N-isopropyl-3-amino-3-hydroxy-2-phenylpropanamide, the structural formula is as follows:

[0064]

[0065] The calculation results of the pKa of the aqueous solutions of Compound 1, Compound 2 and Compound 3 are as attached Figure 2 , and the comparison of the reaction rate constants is as attached Figure 3 . It can be seen that the alkalinity of these three compounds is close to that of monoethanolamine and diethanolamine. According to the calculation results of the reaction rate constants, the reaction rate constants of Compound 1, Compound 2 and Compound 3 with COS are all higher than those with CO2; in contrast, the reaction rate constants of monoethanolamine and diethanolamine with COS are lower than those with CO2.

[0066] Test the selective removal effect of the desulfurization solvent on COS / CO2 in the gas. The desulfurization absorption experimental process is as Figure 1 shown. The raw gas 1 contacts with the absorption liquid in the absorption tower 11 in a countercurrent phase to remove the acidic components, and the purified gas 2 obtained is discharged from the top of the tower. The rich liquid 5 from the absorption tower that has absorbed the acidic components comes out from the bottom of the tower and then enters the rich liquid flash tank 12. The flash gas 3 obtained by flashing is rich in hydrocarbons that are easy to dissolve. The rich liquid 6 from the flash tank after flashing exchanges heat with the regenerated lean liquid 8 in the heat exchanger 15, and the rich liquid 7 from the heat exchanger enters the regeneration tower 13 for desorption and regeneration. The acidic gas 4 is discharged from the top of the regeneration tower condenser 16 at the top of the regeneration tower 13 and then sent to the sulfur recovery unit to recover sulfur. The regenerated lean liquid 8 is discharged from the bottom of the regeneration tower reboiler 17 at the bottom of the tower. After being cooled by the rich and lean liquid heat exchanger 15, it enters the regenerated lean liquid cooler 14 as the lean liquid 9 from the heat exchanger for further cooling. The lean liquid 10 from the cooler is used as the liquid returning to the absorption tower 11 for recycling.

[0067] The absorption tower 11 is 1.2 meters high, with 20 theoretical plates, filled with random packing inside. The temperature control accuracy is ±0.2 °C, and the internal gas-liquid contact mode is countercurrent contact. Before the experiment, the tower was washed with deionized water for 40 minutes, and then rinsed with the absorption solvent for 30 minutes. The temperature of the absorption tower and the temperature of the feed preheater of the absorption tower 11 were set. Then, the raw material gas 1 was introduced. After 40 minutes of absorption, the purified gas was taken for detection, compared with the content of the raw material gas, and the removal rates of H2S, COS, and CO2 were calculated. The calculation method of the removal rate α of each component is as follows:

[0068]

[0069] Among them, C1 and C2 are the concentrations of each component in the raw material gas and the purified gas respectively. The contents of H2S and CO2 were detected by using gas detection tubes produced by Hebi Hua'an Gas Detection Technology Co., Ltd., and the content of COS was detected by using a GC920 gas chromatograph produced by Shanghai Haixin Chromatographic Analysis Technology Co., Ltd.

[0070] This embodiment is implemented on the premise of the technical solution of the present invention, and gives detailed implementation methods and specific operation processes, but the protection scope of the present invention is not limited to the following embodiments.

[0071] The following are more detailed implementation cases, which further illustrate the technical solution of the present invention and the technical effects that can be obtained through the following implementation cases.

[0072] In the following embodiments, unless otherwise specified, the raw material reagents or treatment technologies indicate that they are all conventional commercially available products or conventional treatment technologies in the art.

[0073] In the following embodiments, polyethylene glycol ether was purchased from Shandong Xiya Chemical Co., Ltd., with an AR grade purity; polysiloxane was purchased from Jinan Hongli Chemical Co., Ltd., with a purity of ≥99%. The mass fraction of polyethylene glycol ether and polysiloxane is based on the total mass of compound 1, compound 2, or compound 3 and the alkanolamine reagent.

[0074] Example 1

[0075] The raw material gas with the following composition was used: hydrogen sulfide 30.2 mg / Nm 3 , carbonyl sulfide 146 mg / Nm 3 , carbon dioxide 21.58% mol / mol, oxygen 0.201% mol / mol, and the balance is nitrogen.

[0076] An absorption solution with the following composition (all in mass fraction) is used: 60% N-methyl diethanolamine, 40% N-ethyl-2-methylamino-2-phenylacetamide (Compound 1); 0.3% polyglycol ether, 0.01% polysiloxane (relative to N-methyl diethanolamine + Compound 1). A desulfurization solvent is prepared and then formulated into an aqueous solution with water in a mass ratio of 4:6. The absorption temperature is 40 °C, the absorption pressure is 101.3 kPa, the raw gas flow rate is 36 L / h, and the absorption solution flow rate is 0.12 L / h.

[0077] The hydrogen sulfide removal rate is 100%, the carbonyl sulfide removal rate is 68.37%, and the carbon dioxide removal rate is 29.53%.

[0078] Example 2

[0079] The raw gas with the following composition is used: 30.2 mg / Nm hydrogen sulfide 3 , 146 mg / Nm carbonyl sulfide 3 , 21.58% mol / mol carbon dioxide, 0.201% mol / mol oxygen, and the balance is nitrogen.

[0080] An absorption solution with the following composition (all in mass fraction) is used: 40% diethanolamine, 60% N-ethyl-2-hydroxymethyl-2-phenylacetamide (Compound 2), 0.3% polyglycol ether, 0.01% polysiloxane. A desulfurization solvent is prepared and then formulated into an aqueous solution with water in a mass ratio of 4:6. The absorption temperature is 40 °C, the absorption pressure is 101.3 kPa, the raw gas flow rate is 24 L / h, and the absorption solution flow rate is 0.12 L / h.

[0081] The hydrogen sulfide removal rate is 100%, the carbonyl sulfide removal rate is 50.46%, and the carbon dioxide removal rate is 44.19%.

[0082] Example 3

[0083] The raw gas with the following composition is used: 30.2 mg / Nm hydrogen sulfide 3 , 146 mg / Nm carbonyl sulfide 3 , 21.58% mol / mol carbon dioxide, 0.201% mol / mol oxygen, and the balance is nitrogen.

[0084] An absorption solution with the following composition (all in mass fraction) is used: 50% ethanolamine, 50% N-isopropyl-3-amino-3-hydroxy-2-phenylpropanamide (Compound 3), 0.3% polyglycol ether, 0.01% polysiloxane. A desulfurization solvent is prepared and then formulated into an aqueous solution with water in a mass ratio of 4:6. The absorption temperature is 40 °C, the absorption pressure is 101.3 kPa, the raw gas flow rate is 24 L / h, and the absorption solution flow rate is 0.12 L / h.

[0085] The hydrogen sulfide removal rate is 100%, the carbonyl sulfide removal rate is 71.29%, and the carbon dioxide removal rate is 5.37%.

[0086] Example 4

[0087] The feed gas has the following composition: hydrogen sulfide 30.2 mg / Nm 3 , carbonyl sulfide 146 mg / Nm 3 , carbon dioxide 21.58% mol / mol, oxygen 0.201% mol / mol, and the balance is nitrogen.

[0088] The absorption solution has the following composition (all mass fractions): ethanolamine 50%, N-isopropyl-3-amino-3-hydroxy-2-phenylpropanamide (Compound 3) 50%, polyglycol ether 0.3%, and polysiloxane 0.01%. It is formulated into a desulfurization solvent, and then formulated into an aqueous solution with water according to a mass ratio of 4:6. The absorption temperature is 30 °C, the absorption pressure is 101.3 kPa, the feed gas flow rate is 24 L / h, and the absorption solution flow rate is 0.12 L / h.

[0089] The hydrogen sulfide removal rate is 100%, the carbonyl sulfide removal rate is 58.54%, and the carbon dioxide removal rate is 3.49%.

[0090] Example 5

[0091] The feed gas has the following composition: hydrogen sulfide 30.2 mg / Nm 3 , carbonyl sulfide 146 mg / Nm 3 , carbon dioxide 21.58% mol / mol, oxygen 0.201% mol / mol, and the balance is nitrogen.

[0092] The absorption solution has the following composition (all mass fractions): ethanolamine 50%, N-isopropyl-3-amino-3-hydroxy-2-phenylpropanamide (Compound 3) 50%, polyglycol ether 0.3%, and polysiloxane 0.01%. It is formulated into a desulfurization solvent, and then formulated into an aqueous solution with water according to a mass ratio of 4:6. The absorption temperature is 50 °C, the absorption pressure is 101.3 kPa, the feed gas flow rate is 24 L / h, and the absorption solution flow rate is 0.12 L / h.

[0093] The hydrogen sulfide removal rate is 100%, the carbonyl sulfide removal rate is 81.56%, and the carbon dioxide removal rate is 4.65%.

[0094] Example 6

[0095] The feed gas has the following composition: hydrogen sulfide 30.2 mg / Nm 3 , carbonyl sulfide 146 mg / Nm 3 , carbon dioxide 1.95% mol / mol, oxygen 0.201% mol / mol, and the balance is nitrogen.

[0096] An absorption solution with the following composition (all in mass fraction) is used: ethanolamine 50%, N-isopropyl-3-amino-3-hydroxy-2-phenylpropanamide (Compound 3) 50%, polyglycol ether 0.3%, polysiloxane 0.01%. It is formulated into a desulfurization solvent, and then formulated into an aqueous solution with water according to a mass ratio of 4:6. The absorption temperature is 40 °C, the absorption pressure is 101.3 kPa, the raw gas flow rate is 24 L / h, and the absorption solution flow rate is 0.12 L / h.

[0097] The hydrogen sulfide removal rate is 100%, the carbonyl sulfide removal rate is 100%, and the carbon dioxide removal rate is 53.5%.

[0098] Example 7

[0099] The raw gas with the following composition is used: hydrogen sulfide 50.4 mg / Nm 3 , carbonyl sulfide 98.5 mg / Nm 3 , carbon dioxide 2.00% mol / mol, carbon disulfide 190 mg / Nm 3 , oxygen 0.201% mol / mol, and the balance is nitrogen.

[0100] An absorption solution with the following composition (all in mass fraction) is used: ethanolamine 50%, N-isopropyl-3-amino-3-hydroxy-2-phenylpropanamide (Compound 3) 50%, polyglycol ether 0.3%, polysiloxane 0.01%. It is formulated into a desulfurization solvent, and then formulated into an aqueous solution with water according to a mass ratio of 4:6. The absorption temperature is 40 °C, the absorption pressure is 101.3 kPa, the raw gas flow rate is 24 L / h, and the absorption solution flow rate is 0.12 L / h.

[0101] The hydrogen sulfide removal rate is 100%, the carbonyl sulfide removal rate is 100%, the carbon dioxide removal rate is 55.37%, and the carbon disulfide removal rate is 99.8%

[0102] Example 8

[0103] The raw gas with the following composition is used: hydrogen sulfide 4.99% mol / mol, carbonyl sulfide 275.9 mg / Nm 3 , carbon dioxide 5.04% mol / mol, methanethiol 675.1 mg / Nm 3 , and the balance is nitrogen.

[0104] An absorption solution with the following composition (all in mass fractions) is used: 60% N-methyldiethanolamine, 40% N-ethyl-2-methylamino-2-phenylacetamide (Compound 1), 0.3% polyglycol ether, 0.01% polysiloxane. It is formulated into a desulfurization solvent, and then an aqueous solution is prepared by mixing it with water in a mass ratio of 4:6. The absorption temperature is 40 °C, the absorption pressure is 101.3 kPa, the raw gas flow rate is 24 L / h, and the absorption solution flow rate is 0.12 L / h.

[0105] The removal rate of hydrogen sulfide is 100%, the removal rate of carbonyl sulfide is 87.97%, the removal rate of carbon dioxide is 82.14%, and the removal rate of methanethiol is 87.63%.

[0106] Example 9

[0107] The raw gas has the following composition: 4.99% mol / mol hydrogen sulfide, 275.9 mg / Nm carbonyl sulfide 3 , 5.04% mol / mol carbon dioxide, 675.1 mg / Nm methanethiol 3 , with the balance being nitrogen.

[0108] An absorption solution with the following composition (all in mass fractions) is used: 60% N-methyldiethanolamine, 40% N-ethyl-2-hydroxymethyl-2-phenylacetamide (Compound 2), 0.3% polyglycol ether, 0.01% polysiloxane. It is formulated into a desulfurization solvent, and then an aqueous solution is prepared by mixing it with water in a mass ratio of 4:6. The absorption temperature is 40 °C, the absorption pressure is 101.3 kPa, the raw gas flow rate is 24 L / h, and the absorption solution flow rate is 0.12 L / h.

[0109] The removal rate of hydrogen sulfide is 100%, the removal rate of carbonyl sulfide is 68.68%, the removal rate of carbon dioxide is 58.33%, and the removal rate of methanethiol is 72.91%.

[0110] Example 10

[0111] The raw gas has the following composition: 4.99% mol / mol hydrogen sulfide, 275.9 mg / Nm carbonyl sulfide 3 , 5.04% mol / mol carbon dioxide, 675.1 mg / Nm methanethiol 3 , with the balance being nitrogen.

[0112] An absorption solution with the following composition (all in mass fractions) is used: 60% N-methyldiethanolamine, 40% N-isopropyl-3-amino-3-hydroxy-2-phenylpropanamide (Compound 3), 0.3% polyglycol ether, 0.01% polysiloxane. It is formulated into a desulfurization solvent, and then an aqueous solution is prepared by mixing it with water in a mass ratio of 4:6. The absorption temperature is 40 °C, the absorption pressure is 101.3 kPa, the raw gas flow rate is 24 L / h, and the absorption solution flow rate is 0.12 L / h.

[0113] The hydrogen sulfide removal rate is 100%, the carbonyl sulfide removal rate is 51.94%, the carbon dioxide removal rate is 28.57%, and the methanethiol removal rate is 55.04%.

[0114] Comparative Example 1

[0115] The feed gas with the following composition was used: hydrogen sulfide 30.2 mg / Nm 3 , carbonyl sulfide 146 mg / Nm 3 , carbon dioxide 21.58% mol / mol, oxygen 0.201% mol / mol, and the balance being nitrogen.

[0116] The absorption solution with the following composition was used: an aqueous solution of tert-butylaminoethoxyethanol with a mass fraction of 40%, an absorption temperature of 40 °C, an absorption pressure of 101.3 kPa, a feed gas flow rate of 30 L / h, and an absorption solution flow rate of 0.12 L / h.

[0117] The hydrogen sulfide removal rate is 100%, the carbonyl sulfide removal rate is 17.48%, and the carbon dioxide removal rate is 86.05%.

[0118] Comparative Example 2

[0119] The feed gas with the following composition was used: hydrogen sulfide 30.2 mg / Nm 3 , carbonyl sulfide 146 mg / Nm 3 , carbon dioxide 21.58% mol / mol, oxygen 0.201% mol / mol, and the balance being nitrogen.

[0120] The absorption solution with the following composition was used: an aqueous solution of N-methyldiethanolamine with a mass fraction of 40%, an absorption temperature of 40 °C, an absorption pressure of 101.3 kPa, a feed gas flow rate of 30 L / h, and an absorption solution flow rate of 0.12 L / h.

[0121] The hydrogen sulfide removal rate is 100%, the carbonyl sulfide removal rate is 9.60%, and the carbon dioxide removal rate is 46.59%.

[0122] Comparative Example 3

[0123] The feed gas with the following composition was used: hydrogen sulfide 30.2 mg / Nm 3 , carbonyl sulfide 146 mg / Nm 3 , carbon dioxide 21.58% mol / mol, oxygen 0.201% mol / mol, and the balance being nitrogen.

[0124] An absorption solution with the following composition (all in mass fraction) is used: 0.3% of polyethylene glycol ether and 0.01% of polysiloxane are added to N-methyldiethanolamine to prepare a desulfurization solvent, and then an aqueous solution is prepared by mixing it with water in a mass ratio of 4:6. The absorption temperature is 40°C, the absorption pressure is 101.3 kPa, the flow rate of the raw gas is 36 L / h, and the flow rate of the absorption solution is 0.12 L / h.

[0125] The removal rate of hydrogen sulfide is 100%, the removal rate of carbonyl sulfide is 9.68%, and the removal rate of carbon dioxide is 46.95%.

[0126] Comparative Example 4

[0127] The raw gas with the following composition is used: 30.2 mg / Nm of hydrogen sulfide 3 , 146 mg / Nm of carbonyl sulfide 3 , 21.58% mol / mol of carbon dioxide, 0.201% mol / mol of oxygen, and the balance is nitrogen.

[0128] An absorption solution with the following composition (all in mass fraction) is used: 0.3% of polyethylene glycol ether and 0.01% of polysiloxane are added to N-ethyl-2-methylamino-2-phenylacetamide (Compound 1) to prepare a desulfurization solvent, and then an aqueous solution is prepared by mixing it with water in a mass ratio of 4:6. The absorption temperature is 40°C, the absorption pressure is 101.3 kPa, the flow rate of the raw gas is 36 L / h, and the flow rate of the absorption solution is 0.12 L / h.

[0129] The removal rate of hydrogen sulfide is 100%, the removal rate of carbonyl sulfide is 41.89%, and the removal rate of carbon dioxide is 2.56%.

[0130] It can be seen that compared with the existing desulfurization solvents, the present invention can efficiently remove hydrogen sulfide, carbonyl sulfide, etc. while reducing the removal rate of carbon dioxide.

[0131] The above description of the embodiments is for the convenience of those of ordinary skill in the art to understand and use the invention. Those skilled in the art can obviously make various modifications to these embodiments easily and apply the general principles described herein to other embodiments without creative labor. Therefore, the present invention is not limited to the above embodiments, and the improvements and modifications made by those skilled in the art without departing from the scope of the present invention should be within the protection scope of the present invention.

Claims

1. A composite solution, characterized in that: The composite solution comprises an amide compound and an alkyl alcohol amine in a mass ratio of 2:3 to 3:2, and a solvent; The structural formula of the amide compound is as follows In the formula, R1 is an alkane branched chain having a carbon number greater than or equal to 2; R2 is an alkane branch with O or N elements; R3 is a substituent having an aromatic structure.

2. The composite solution according to claim 1, characterized in that: The amide compound is one or a combination of phenylacetamide and phenylpropionamide.

3. The composite solution according to claim 2, characterized in that: The amide compound is selected from at least one of N-ethyl-2-methylamino-2-phenylacetamide, N-ethyl-2-hydroxymethyl-2-phenylacetamide, and N-isopropyl-3-amino-3-hydroxy-2-phenylpropionamide.

4. The composite solution according to claim 1, characterized in that: The alkyl alcohol amine is selected from at least one of ethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine or diisopropanolamine.

5. The composite solution according to claim 1, characterized in that: The solvent is water.

6. The composite solution according to claim 1, characterized in that: The composite solution also includes an inhibitor and a regulator; The inhibitor is polypropylene glycol ether, and the amount used is ≤3wt% of the total amount of amide compounds and alkyl alcohol amines; The regulator is polysiloxane, and the amount used is ≤3wt% of the total amount of the amide compound and the alkyl alcohol amine.

7. The composite solution according to claim 6, characterized in that: The total mass concentration of the amide compound, alkyl alcohol amine, inhibitor and regulator in the composite solution is 5-75%.

8. Use of the composite solution according to any one of claims 1 to 7, characterized in that: The composite solution is used for selectively removing carbonyl sulfide from a gas stream containing carbon dioxide.

9. The use of the composite solution according to claim 8, characterized in that: The removal process of carbonyl sulfide includes at least one of the following process conditions: A: The content of carbonyl sulfide in the gas stream containing carbon dioxide is 95-280 mg / Nm 3 ; B: The carbon dioxide content in the carbon dioxide-containing gas stream is 1.5 to 25 mol%; C: The content of hydrogen sulfide in the gas stream containing carbon dioxide is 4.5 to 55 mol%; D: The content of methyl mercaptan in the gas stream containing carbon dioxide is 650-700 mg / Nm 3 .

10. The use of the composite solution according to claim 8, characterized in that: The removal system used includes: An absorption tower (11) is used to selectively remove carbonyl sulfide from a raw gas (1) containing carbon dioxide and carbonyl sulfide by using the composite solution; the obtained purified gas (2) is discharged from the top of the tower, and the rich liquid (5) is discharged from the bottom of the tower; A rich liquid flash tank (12) is used to flash the rich liquid (5) output from the absorption tower, and the obtained flash gas (3) is rich in easily soluble hydrocarbons; The regeneration tower (13) is used to distill the rich liquid (6) from the flash tank, and discharge the acid gas (4) rich in carbonyl sulfide from the top of the tower; the regeneration lean liquid (8) is discharged from the bottom of the tower, and after heat exchange with the rich liquid (6) from the flash tank, it is circulated to the absorption tower (11) as absorption liquid.

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