Preparation method and application of carbon dioxide trapping absorbent for ship tail gas

Abstract

The invention relates to the technical field of separation of carbon dioxide in waste gas, and discloses a preparation method and application of a carbon dioxide trapping absorbent for ship tail gas. The preparation method comprises the following steps: mixing and reacting an absorbent main agent with seawater, and performing solid-liquid separation to obtain a liquid-phase solution; the absorbent main agent comprises hydroxyethyl ethylenediamine and 2, 6-dimethyl-1, 4-dihydro-3, 5-dipyridinedicarboxylic acid diethyl ester, or comprises diethylenetriamine and 2, 2, 6, 6-tetramethylpiperidine, or comprises 2-amino-2-methyl-1-propanol and 1-methyl-4-piperidinol, and the absorbent main agent comprises 2, 6-dimethyl-1, 4-dihydro-3, 5-dipyridinedicarboxylic acid diethyl ester, or comprises diethylenetriamine and 2, 2, 6, 6-tetramethylpiperidine, or comprises 2-amino-2-methyl-1-propanol and 1-methyl-4-piperidinol. Introducing gas containing carbon dioxide into the liquid phase solution, fully mixing and reacting, and removing solid components; by adopting the method disclosed by the invention, the CO2 trapping absorbent can be directly prepared from seawater, fresh water resources are not needed, the energy consumption in the preparation process is low, and the prepared CO2 trapping absorbent can be recycled and regenerated when being used for separating CO2 in ship tail gas, and can realize higher CO2 trapping and absorbing efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of carbon dioxide separation from waste gas, and particularly to a preparation method and application of a carbon dioxide capture absorbent for ship exhaust gas. Background Art

[0002] The shipping industry, which mainly consumes fossil fuels such as heavy oil, is a major emitter of carbon dioxide. The capture of carbon dioxide in ship exhaust gas is an important technology for ship carbon emission reduction. The chemical absorption process based on the circulation of liquid absorbents is a commonly used technology for capturing carbon dioxide in exhaust gas at present, and has been widely used for capturing carbon dioxide in flue gas from fixed sources such as coal-fired and gas-fired power plants. The main process is as follows: an alkaline absorbent reacts with carbon dioxide in the flue gas through an acid-base neutralization reaction. The absorbent that has absorbed carbon dioxide desorbs carbon dioxide gas at high temperature, so as to realize the separation of carbon dioxide from the flue gas. The absorbent that desorbs carbon dioxide is recycled to capture carbon dioxide again. The absorbent is the core of this technology.

[0003] Most of the existing carbon dioxide absorbents are prepared using water (for example, in patent CN118491261A, a composite absorbent is mixed with water to form an aqueous solution for capturing carbon dioxide in ship exhaust gas, where the mass percentage of water is 50 - 85%). A large amount of fresh water is consumed, and seawater contains a high concentration of inorganic salts and cannot be directly used to prepare carbon dioxide absorbents. Due to the lack of fresh water resources on ships (especially ocean-going ships), the carbon dioxide absorbents prepared using water are difficult to be applied on a large scale and operate for a long period on ships. The water consumption loss of the absorption system is large, which will lead to a weakened carbon dioxide absorption effect after it operates for a period of time.

[0004] Patent CN114804455A discloses a method for producing alkali and fixing carbon by coupling bipolar membrane electrodialysis with hollow fiber membrane to treat concentrated seawater. First, the seawater is pretreated by the double-alkali method, and calcium and magnesium ions and other high-valent metal ions in the concentrated seawater are removed by adding sodium hydroxide and sodium carbonate. Then, an acid solution and an alkali solution are prepared by bipolar membrane electrodialysis, and the alkali solution can be used to absorb carbon dioxide. This patent can use seawater to prepare a carbon dioxide absorbent, but the alkali solution cannot be recycled and regenerated, and it needs to be continuously prepared from seawater through "double-alkali method pretreatment - bipolar membrane electrodialysis". The bipolar membrane electrodialysis process has high energy consumption, resulting in that this method is also not conducive to large-scale application and long-term operation on ships. Summary of the Invention

[0005] In order to solve the above technical problems, that is, the existing method for preparing a CO 2 absorbent using seawater has high energy consumption, and the prepared CO 2The absorbent cannot be recycled, which is not conducive to large-scale application and long-term operation on ships. The present invention provides a preparation method and application of a carbon dioxide capture absorbent for ship exhaust gas. By using the method of the present invention, the CO 2 capture absorbent can be directly prepared from seawater without using fresh water resources, and the energy consumption in the preparation process is low. Moreover, the prepared CO 2 capture absorbent can be recycled when used to separate CO 2 from ship exhaust gas, and a high CO 2 capture absorption efficiency can be achieved.

[0006] The specific technical solution of the present invention is as follows: In the first aspect, the present invention provides a preparation method of a carbon dioxide capture absorbent for ship exhaust gas, including: S1: After mixing the absorbent main agent with seawater and reacting, solid-liquid separation is carried out to obtain a liquid-phase solution; the absorbent main agent includes hydroxyethyl ethylenediamine and diethyl 2,6-dimethyl-1,4-dihydro-3,5-pyridinedicarboxylate, or includes diethylenetriamine and 2,2,6,6-tetramethylpiperidine, or includes 2-amino-2-methyl-1-propanol and 1-methyl-4-piperidinol; S2: Carbon dioxide-containing gas is introduced into the liquid-phase solution. After sufficient mixing and reaction, the solid components are removed to obtain a carbon dioxide capture absorbent containing the absorbent main agent.

[0007] In the present invention, specific absorbent main agents are successively reacted with magnesium ions and calcium ions in seawater and CO 2 in the CO 2 -containing gas to generate precipitates. After removing these precipitates, the CO 2 capture absorbent is obtained. The specific process is as follows: (1) In step S1, when seawater is mixed with the absorbent main agent, the following reactions can occur: A + H 2 O ↔ AH + + OH - (absorbent main agent-water balance reaction ①); 2 A + H 2 O + Mg 2+ → 2 AH + + Mg(OH) 2 ; Among them, A represents the absorbent main agent, AH + is the protonated absorbent main agent, and Mg(OH) 2 is the precipitate.

[0008] (2) In step S2, after introducing CO 2 , the following reactions can occur: 2A + H 2 O + CO 2 → AH + + ACOO - (Absorbent main agent and CO 2 main reaction); A + H 2 O + CO 2 → AH + + HCO 3 - ; ACOO - + H 2 O ↔ AH + + HCO 3 - (Equilibrium reaction ②); A + HCO 3 - ↔ AH + + CO 3 2- (Equilibrium reaction ③); Ca 2+ + CO 3 2- → CaCO 3 (Reaction involving calcium ions in seawater); Among them, ACOO - is the carbamate ion, and CaCO 3 is the precipitate; In the above process, as the precipitation reaction occurs, the equilibrium reaction ③ shifts to the right, and HCO 3 - is consumed, which in turn causes the equilibrium reaction ② to shift to the right until the calcium ions in seawater are completely precipitated and a new equilibrium is reached.

[0009] In the CO 2 capture absorbent prepared by the above method, using the absorbent main agent contained therein, can capture and absorb CO 2 , so as to be used for the separation of CO 2 in ship exhaust gas. Moreover, in the process of preparing the CO 2 capture absorbent of the present invention, magnesium ions and calcium ions in seawater can be removed, avoiding the blockage of the carbon dioxide capture system caused by the precipitates formed by magnesium ions and calcium ions when using the CO 2 capture absorbent to separate CO 2 in ship exhaust gas.

[0010] Using the method of the present invention to prepare the CO 2 capture absorbent has the following advantages: 1) The present invention can directly use seawater to prepare CO2 The capture absorbent does not require the use of fresh water resources on ships, nor does it require complex operations for seawater desalination or bipolar membrane electrodialysis for alkali production. The entire preparation process is simple in operation and low in energy consumption, and can be applied on a large scale and operated for a long period on ships; 2) Compared with the CO 2 capture absorbent prepared with fresh water, the CO 2 capture absorbent prepared by the method of the present invention has better CO 2 capture ability. The reason may be that seawater contains sodium, potassium ions, chloride ions, sulfate ions, etc., which can increase the polarity of the absorbent system. In a strong polar system, due to molecular-ion interactions and hydrogen bond interactions, etc., the molecular activity of the main absorbent of the present invention can be improved, thereby promoting the capture and absorption of CO 2 ; 3) When the CO 2 capture absorbent prepared by the present invention is used for the separation of CO 2 in ship exhaust gas, after absorbing CO 2 , CO 2 can be desorbed by heating, realizing the cyclic regeneration of the CO 2 capture absorbent; 4) When the method of the present invention is used to prepare the CO 2 capture absorbent, the equipment size can also be reduced. Taking the preparation of 1 ton of CO 2 capture absorbent containing 30 wt% of the main absorbent and 70 wt% of water as an example, when the conventional method (using fresh water preparation) is used, an absorbent storage tank of about 1 m 3 needs to be set on the ship, while when the method of the present invention is used, only 300 kg of the main absorbent needs to be stored, and the storage tank size is about 0.3 m 3 , which can greatly reduce the equipment floor area and thus save space for the ship.

[0011] In addition, the present invention specially designs the formula of the main absorbent, which can improve the CO 2 capture absorption effect of the capture absorbent on CO 2 in ship exhaust gas: (1) Hydroxyethyl ethylenediamine and diethyl 2,6-dimethyl-1,4-dihydro-3,5-pyridinedicarboxylate: The CO 2 absorption capacity of hydroxyethyl ethylenediamine is large, but it is prone to degradation when used alone. In the present invention, hydroxyethyl ethylenediamine and diethyl 2,6-dimethyl-1,4-dihydro-3,5-pyridinedicarboxylate are used in combination. The conjugated effect and steric effect generated by diethyl 2,6-dimethyl-1,4-dihydro-3,5-pyridinedicarboxylate can be utilized to capture the active free radicals generated by hydroxyethyl ethylenediamine in the carbon dioxide capture process flow, convert them into stable substances, thereby terminating the free radical chain reaction, improving the degradation problem of hydroxyethyl ethylenediamine, and thus improving the CO 2The capture absorption efficiency of the capture absorbent for CO 2 is improved, and its stability during long-term operation is enhanced.

[0012] (2) Diethylenetriamine and 2,2,6,6-tetramethylpiperidine: Similar to the coordination mechanism between hydroxyethyl ethylenediamine and diethyl 2,6-dimethyl-1,4-dihydro-3,5-pyridinedicarboxylate, diethylenetriamine has strong CO 2 absorption capacity, but it is prone to degradation when used alone. However, 2,2,6,6-tetramethylpiperidine can improve the degradation problem of diethylenetriamine through conjugation effect and steric effect, thereby enhancing the CO 2 capture absorption efficiency and the long-term operation stability of the CO 2 capture absorbent.

[0013] (3) 2-Amino-2-methyl-1-propanol and 1-methyl-4-piperidinol: When 2-amino-2-methyl-1-propanol is used alone, there is a large volatilization loss and the CO 2 absorption mass transfer rate is slow. After compounding 2-amino-2-methyl-1-propanol with 1-methyl-4-piperidinol, intermolecular hydrogen bonding occurs between them, which can effectively reduce the volatilization loss of 2-amino-2-methyl-1-propanol. Moreover, 1-methyl-4-piperidinol can also provide hydrogen protons for the reaction between 2-amino-2-methyl-1-propanol and CO 2 , thus enhancing the CO 2 absorption reaction rate and the long-term operation stability of the CO 2 capture absorbent.

[0014] Preferably, in step S1, the mass ratio of hydroxyethyl ethylenediamine to diethyl 2,6-dimethyl-1,4-dihydro-3,5-pyridinedicarboxylate is 1:0.0019 - 0.1, the mass ratio of diethylenetriamine to 2,2,6,6-tetramethylpiperidine is 1:0.0033 - 0.2, and the mass ratio of 2-amino-2-methyl-1-propanol to 1-methyl-4-piperidinol is 1:0.15 - 1.6.

[0015] Under the above ratios, good pairwise synergistic effects can be generated among the main components of each absorbent, thereby achieving higher CO 2 capture absorption efficiency and long-term operation stability.

[0016] Preferably, in step S1, the mass ratio of the main absorbent to seawater is 1:0.25 - 4.

[0017] Preferably, in step S1, the temperature of the mixing reaction is 20 - 70 °C and the time is 30 - 120 min.

[0018] Preferably, in step S1, the solid-liquid separation method is suction filtration, pressure filtration or centrifugal filtration; the conditions for suction filtration are: the filter membrane pore size is 0.1 - 0.25 μm, the absolute pressure is 0.1 - 1 kPa, and the temperature is 20 - 50 °C; the conditions for pressure filtration are: the absolute pressure is 0.1 - 1 MPa, and the temperature is 20 - 50 °C; the conditions for centrifugal filtration are: the rotation speed is 6000 - 10000 r / min, and the temperature is 20 - 50 °C.

[0019] Preferably, in step S1, the molar ratio between the absorbent main agent and the carbon dioxide contained in the liquid-phase solution after introducing the carbon dioxide-containing gas in step S2 is 1:0.1 - 0.5.

[0020] Preferably, in step S2, the carbon dioxide-containing gas is one or more of pure carbon dioxide gas, desulfurized ship exhaust gas, and a mixture of carbon dioxide and inert gas; the carbon dioxide-containing gas is introduced into the liquid-phase solution by means of bubble contact with an aeration head, and the gas flow rate is 0.2 - 2 m 3 / h / kg liquid-phase solution, and the temperature is 20 - 70 °C.

[0021] Preferably, in step S2, the method of fully mixing and reacting is one or more of stirring, standing still, and ultrasonic oscillation; the rotation speed of the stirring is 500 - 2000 r / min, the temperature is 20 - 50 °C, and the time is 0.5 - 10 h; the temperature for standing still is 20 - 50 °C, and the time is 0.5 - 10 hours; the frequency of the ultrasonic oscillation is 20 - 100 Hz, the temperature is 20 - 50 °C, the total duration is 0.5 - 2 h, and there is an intermittent period of 5 - 10 min after each ultrasonic treatment for 20 - 50 min.

[0022] Preferably, in step S2, the method of removing solid components is suction filtration, pressure filtration or centrifugal filtration; the conditions for suction filtration are: the filter membrane pore size is 0.2 - 0.5 μm, the absolute pressure is 0.1 - 10 kPa, and the temperature is 20 - 50 °C; the conditions for pressure filtration are: the absolute pressure is 0.1 - 1 MPa, and the temperature is 20 - 50 °C; the conditions for centrifugal filtration are: the rotation speed is 5000 - 10000 r / min, and the temperature is 20 - 50 °C.

[0023] In a second aspect, the present invention provides the application of a carbon dioxide capture absorbent in separating carbon dioxide in ship exhaust gas, and the carbon dioxide capture absorbent is prepared by the preparation method described above.

[0024] Compared with the prior art, the present invention has the following advantages: (1) By using the method of the present invention, it is possible to directly prepare a CO 2 capture absorbent from seawater, avoiding the blockage of the carbon dioxide capture system caused by the formation of precipitates of calcium ions and magnesium ions existing in seawater. CO 2The entire preparation process of the capture absorbent does not require the use of fresh water resources and has low energy consumption. 2 The capture absorbent is used to capture CO 2 It has good capture and absorption capabilities and can be recycled, which is conducive to large-scale application and long-term operation on ships.

[0025] (2) In the absorbent main agent used in the present invention, hydroxyethylethylenediamine and 2,6-dimethyl-1,4-dihydro-3,5-pyridinedicarboxylic acid diethyl ester, diethylenetriamine and 2,2,6,6-tetramethylpiperidine, 2-amino-2-methyl-1-propanol and 1-methyl-4-piperidinol can produce a good coordination effect, so that the obtained CO 2 The capture absorbent has a high CO 2 The capture and absorption efficiency is high and it has good stability in long-term operation. DETAILED DESCRIPTION

[0026] The present invention will be further described below in conjunction with the embodiments.

[0027] A method for preparing a carbon dioxide capture absorbent for ship exhaust gas, comprising: S1: After mixing the absorbent main agent with seawater for reaction, solid-liquid separation is performed to obtain a liquid phase solution; the absorbent main agent includes hydroxyethylethylenediamine and 2,6-dimethyl-1,4-dihydro-3,5-pyridinedicarboxylic acid diethyl ester, or includes diethylenetriamine and 2,2,6,6-tetramethylpiperidine, or includes 2-amino-2-methyl-1-propanol and 1-methyl-4-piperidinol; S2: introducing a carbon dioxide-containing gas into the liquid phase solution, mixing and reacting the solution thoroughly, and then removing the solid components to obtain a carbon dioxide capture absorbent containing an absorbent main agent.

[0028] In some specific embodiments, in step S1, the mass ratio of hydroxyethylethylenediamine to diethyl 2,6-dimethyl-1,4-dihydro-3,5-pyridinedicarboxylate is 1:0.0019~0.1, the mass ratio of diethylenetriamine to 2,2,6,6-tetramethylpiperidine is 1:0.0033~0.2, and the mass ratio of 2-amino-2-methyl-1-propanol to 1-methyl-4-piperidinol is 1:0.15~1.6.

[0029] In some specific embodiments, in step S1, the mass ratio of the absorbent main agent to seawater is 1:0.25~4.

[0030] In some specific embodiments, in step S1, the temperature of the mixing reaction is 20-70° C., and the time is 30-120 min.

[0031] In some specific embodiments, in step S1, the solid-liquid separation method is suction filtration, pressure filtration or centrifugal filtration; the conditions for suction filtration are: the filter membrane pore size is 0.1-0.25 μm, the absolute pressure is 0.1-1 kPa, and the temperature is 20-50 °C; the conditions for pressure filtration are: the absolute pressure is 0.1-1 MPa, and the temperature is 20-50 °C; the conditions for centrifugal filtration are: the rotation speed is 6000-10000 r / min, and the temperature is 20-50 °C.

[0032] In some specific embodiments, in step S1, the molar ratio between the absorbent main agent and the carbon dioxide contained in the liquid-phase solution after introducing the carbon dioxide-containing gas in step S2 is 1:0.1-0.5.

[0033] In some specific embodiments, in step S2, the carbon dioxide-containing gas is one or more of pure carbon dioxide gas, desulfurized ship exhaust gas, and a mixture of carbon dioxide and inert gas.

[0034] In some specific embodiments, in step S2, the carbon dioxide-containing gas is introduced into the liquid-phase solution by the bubbling contact method using an aeration head, and the gas flow rate is 0.2-2 m 3 / h / kg liquid-phase solution, and the temperature is 20-70 °C.

[0035] In some specific embodiments, in step S2, the method of sufficient mixing and reaction is one or more of stirring, standing, and ultrasonic oscillation; the rotation speed of the stirring is 500-2000 r / min, the temperature is 20-50 °C, and the time is 0.5-10 h; the temperature for standing is 20-50 °C, and the time is 0.5-10 hours; the frequency of the ultrasonic oscillation is 20-100 Hz, the temperature is 20-50 °C, the total duration is 0.5-2 h, and there is an intermittent period of 5-10 min after each ultrasonic treatment for 20-50 min.

[0036] In some specific embodiments, in step S2, the method of removing solid components is suction filtration, pressure filtration or centrifugal filtration; the conditions for suction filtration are: the filter membrane pore size is 0.2-0.5 μm, the absolute pressure is 0.1-10 kPa, and the temperature is 20-50 °C; the conditions for pressure filtration are: the absolute pressure is 0.1-1 MPa, and the temperature is 20-50 °C; the conditions for centrifugal filtration are: the rotation speed is 5000-10000 r / min, and the temperature is 20-50 °C.

[0037] Application of a carbon dioxide capture absorbent in separating carbon dioxide in ship exhaust gas, wherein the carbon dioxide capture absorbent is prepared by the described preparation method.

[0038] The present invention will be described below through specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. Without departing from the spirit and scope of the inventive concept, changes and advantages that can be conceived by those skilled in the art are included in the present invention, and the protection scope of the present invention is defined by the appended claims and any equivalents thereof.

[0039] Example 1 Prepare a CO capture absorbent for ship exhaust gas according to the following steps: 2 Capture absorbent: S1: Use hydroxyethyl ethylenediamine and diethyl 2,6-dimethyl-1,4-dihydropyridine-3,5-dicarboxylate with a mass ratio of 1:0.0019 as the main absorbent. Add the main absorbent to seawater according to a mass ratio of 3:7, and stir at 20 °C for 120 min to obtain a mixed solution A.

[0040] S2: Centrifuge and filter the mixed solution A to remove solid components. The centrifuge speed is 6000 r / min and the temperature is 20 °C to obtain a liquid-phase solution.

[0041] S3: Adopt the bubbling contact method with an aeration head to introduce pure CO gas into the liquid-phase solution. The gas flow rate is 0.2 m³ / h / kg of the liquid-phase solution, and the temperature is 20 °C to obtain a mixed solution B. The molar ratio of CO contained in the mixed solution B to the main absorbent added in step S1 is 0.1:1. 2 gas, 3 / h / kg liquid-phase solution, 2 and the temperature is 20 °C to obtain a mixed solution B. The molar ratio of CO contained in the mixed solution B to the main absorbent added in step S1 is 0.1:1.

[0042] S4: Mechanically stir the mixed solution B at a speed of 500 r / min at 20 °C for 2 hours, then perform intermittent ultrasonic oscillation. The ultrasonic frequency is 20 Hz and the temperature is 20 °C. After each 20-min ultrasonic oscillation, there is an intermittent period of 5 min, and the total duration is 1 hour to obtain a mixed solution C.

[0043] S5: Filter the mixed solution C by suction to remove solid components. The pore size of the filter membrane is 0.22 μm, the suction filtration pressure is 0.1 Pa (absolute pressure), and the temperature is 20 °C to obtain a CO capture absorbent. 2 Capture absorbent.

[0044] Example 2 Prepare a CO capture absorbent for ship exhaust gas according to the following steps: 2 Capture absorbent: S1: Use diethylenetriamine and 2,2,6,6-tetramethylpiperidine with a mass ratio of 1:0.2 as the main absorbent. Add the main absorbent to seawater according to a mass ratio of 3:7, and stir at 70 °C for 30 min to obtain a mixed solution A.

[0045] S2: Centrifuge and filter the mixture A to remove the solid components at a centrifuge speed of 10,000 r / min and a temperature of 20 °C to obtain a liquid-phase solution.

[0046] S3: Adopt the bubbling contact method with an aeration head to introduce pure CO 2 gas into the liquid-phase solution at a gas flow rate of 0.5 m 3 / h / kg of the liquid-phase solution and a temperature of 20 °C to obtain a mixture B, and the molar ratio of CO 2 contained in the mixture B to the absorbent main agent added in step S1 is 0.5:1.

[0047] S4: Let the mixture B stand for 2 hours at 20 °C to obtain a mixture C.

[0048] S5: Filter the mixture C by suction to remove the solid components. The pore size of the filter membrane is 0.45 μm, the suction filtration pressure is 10 kPa (absolute pressure), and the temperature is 20 °C to obtain a CO 2 capturing absorbent.

[0049] Example 3 Prepare a CO 2 capturing absorbent for ship exhaust gas according to the following steps: S1: Use 2-amino-2-methyl-1-propanol and 1-methyl-4-piperidinol with a mass ratio of 1:0.15 as the absorbent main agent, and add the absorbent main agent to seawater according to a mass ratio of 3:7, and stir at 20 °C for 30 min to obtain a mixture A.

[0050] S2: Centrifuge and filter the mixture A to remove the solid components at a centrifuge speed of 10,000 r / min and a temperature of 20 °C to obtain a liquid-phase solution.

[0051] S3: Adopt the bubbling contact method with an aeration head to introduce a mixture of CO 2 and N 2 (where the volume fraction of CO 2 is 10%) into the liquid-phase solution at a gas flow rate of 2 m 3 / h / kg of the liquid-phase solution and a temperature of 20 °C to obtain a mixture B, and the molar ratio of CO 2 contained in the mixture B to the absorbent main agent added in step S1 is 0.5:1.

[0052] S4: Perform intermittent ultrasonic oscillation on the mixture B at an ultrasonic frequency of 40 Hz and a temperature of 20 °C. After each ultrasonic oscillation for 30 min, there is an intermittent period of 10 min, and the total duration is 2 hours to obtain a mixture C.

[0053] S5: Filter the liquid mixture C to remove the solid components. The pore size of the filter membrane is 0.45 μm, the filtration pressure is 10 kPa (absolute pressure), and the temperature is 20 °C to obtain the CO 2 Capture absorbent.

[0054] Example 4 Prepare the CO 2 capture absorbent for ship exhaust gas according to the following steps: S1: Use hydroxyethyl ethylenediamine and diethyl 2,6-dimethyl-1,4-dihydropyridine-3,5-dicarboxylate with a mass ratio of 1:0.1 as the main absorbent. Add the main absorbent to seawater according to a mass ratio of 3:7 and stir at 30 °C for 60 min to obtain the liquid mixture A.

[0055] S2: Centrifuge and filter the liquid mixture A to remove the solid components. The centrifuge speed is 10000 r / min and the temperature is 20 °C to obtain the liquid phase solution.

[0056] S3: Adopt the bubbling contact method with an aeration head to introduce a gas mixture of CO 2 and N 2 into the liquid phase solution (the volume fraction of CO 2 is 10%), the gas flow rate is 2 m 3 / h / kg liquid phase solution, and the temperature is 20 °C to obtain the liquid mixture B. The molar ratio of CO 2 contained in the liquid mixture B to the main absorbent added in step S1 is 0.2:1.

[0057] S4: Mechanically stir the liquid mixture B at a speed of 2000 r / min for 2 hours at 20 °C, then let it stand at 20 °C for 10 hours, and then perform intermittent ultrasonic oscillation. The ultrasonic frequency is 100 Hz and the temperature is 20 °C. After each 20-min ultrasonic oscillation, there is an intermittent period of 5 min, and the total duration is 1 hour to obtain the liquid mixture C.

[0058] S5: Centrifuge and filter the liquid mixture C to remove the solid components. The centrifuge speed is 8000 r / min and the temperature is 20 °C to obtain the CO 2 capture absorbent.

[0059] Example 5 Prepare the CO 2 capture absorbent for ship exhaust gas according to the following steps: S1: Use diethylenetriamine and 2,2,6,6-tetramethylpiperidine with a mass ratio of 1:0.0033 as the main absorbent. Add the main absorbent to seawater according to a mass ratio of 3:7 and stir at 40 °C for 30 min to obtain the liquid mixture A.

[0060] S2: Centrifuge and filter the mixture A to remove solid components at a centrifuge speed of 10,000 r / min and a temperature of 20 °C to obtain a liquid-phase solution.

[0061] S3: Adopt the bubbling contact method with an aeration head to introduce pure CO 2 gas into the liquid-phase solution at a gas flow rate of 0.5 m 3 / h / kg liquid-phase solution and a temperature of 20 °C to obtain a mixture B, and the molar ratio of CO 2 contained in the mixture B to the absorbent main agent added in step S1 is 0.5:1.

[0062] S4: Let the mixture B stand for 2 hours at 20 °C to obtain a mixture C.

[0063] S5: Carry out suction filtration on the mixture C to remove solid components, with a filter membrane pore size of 0.45 μm and a suction filtration pressure of 10 kPa (absolute pressure) at a temperature of 20 °C to obtain a CO 2 capturing absorbent.

[0064] Example 6 Prepare a CO 2 capturing absorbent for ship exhaust gas according to the following steps: S1: Use 2-amino-2-methyl-1-propanol and 1-methyl-4-piperidinol with a mass ratio of 1:1.6 as the absorbent main agent, and add the absorbent main agent to seawater according to a mass ratio of 3:7, and stir at 25 °C for 60 min to obtain a mixture A.

[0065] S2: Centrifuge and filter the mixture A to remove solid components at a centrifuge speed of 10,000 r / min and a temperature of 20 °C to obtain a liquid-phase solution.

[0066] S3: Adopt the bubbling contact method with an aeration head to introduce a mixture of CO 2 and N 2 (where the volume fraction of CO 2 is 10%) into the liquid-phase solution at a gas flow rate of 2 m 3 / h / kg liquid-phase solution and a temperature of 20 °C to obtain a mixture B, and the molar ratio of CO 2 contained in the mixture B to the absorbent main agent added in step S1 is 0.5:1.

[0067] S4: Carry out intermittent ultrasonic oscillation on the mixture B at an ultrasonic frequency of 40 Hz and a temperature of 20 °C. After each 30-min ultrasonic oscillation, there is an intermittent period of 10 min, and the total duration is 2 hours to obtain a mixture C.

[0068] S5: Filter the mixture C to remove solid components. The pore size of the filter membrane is 0.45 μm, the filtration pressure is 10 kPa (absolute pressure), and the temperature is 20 °C to obtain CO 2 Capture absorbent.

[0069] Comparative Example 1 In this comparative example, deionized water was used to prepare the CO 2 Capture absorbent. Specifically, the steps for preparing the CO 2 Capture absorbent for ship exhaust are as follows: Use hydroxyethyl ethylenediamine and diethyl 2,6-dimethyl-1,4-dihydro-3,5-pyridinedicarboxylate with a mass ratio of 1:0.0019 as the main absorbent. Add the main absorbent to deionized water according to a mass ratio of 3:7, and stir at 25 °C for 60 min to obtain the CO 2 Capture absorbent.

[0070] Comparative Example 2 The difference between this comparative example and Example 1 is only that: hydroxyethyl ethylenediamine is used as the main absorbent; the remaining steps are the same as those in Example 1. Specifically, the steps for preparing the CO 2 Capture absorbent for ship exhaust are as follows: S1: Add hydroxyethyl ethylenediamine to seawater according to a mass ratio of 3:7, and stir at 20 °C for 120 min to obtain mixture A.

[0071] S2: Centrifuge and filter the mixture A to remove solid components. The centrifuge speed is 6000 r / min, and the temperature is 20 °C to obtain a liquid-phase solution.

[0072] S3: Use a bubble contact method with an aeration head to introduce pure CO 2 gas. The gas flow rate is 0.2 m 3 / h / kg liquid-phase solution, and the temperature is 20 °C to obtain mixture B. The molar ratio of CO 2 contained in mixture B to the hydroxyethyl ethylenediamine added in step S1 is 0.1:1.

[0073] S4: Mechanically stir mixture B at a speed of 500 r / min at 20 °C for 2 hours, then perform intermittent ultrasonic oscillation. The ultrasonic frequency is 20 Hz, and the temperature is 20 °C. After each 20 min of ultrasonic oscillation, there is an intermittent period of 5 min, and the total duration is 1 hour to obtain mixture C.

[0074] S5: Filter the mixture C to remove solid components. The pore size of the filter membrane is 0.22 μm, the filtration pressure is 0.1 Pa (absolute pressure), and the temperature is 20 °C to obtain the CO 2 Capture absorbent.

[0075] Comparative Example 3 The difference between this comparative example and Example 1 is only that: diethyl 2,6-dimethyl-1,4-dihydro-3,5-pyridinedicarboxylate is used as the main absorbent; the remaining steps are the same as those in Example 1. Specifically, the steps for preparing the CO 2 capture absorbent for ship exhaust gas are as follows: S1: Add diethyl 2,6-dimethyl-1,4-dihydro-3,5-pyridinedicarboxylate to seawater according to a mass ratio of 3:7, and stir at 20 °C for 120 min to obtain a mixed solution A.

[0076] S2: Centrifuge and filter the mixed solution A to remove solid components. The centrifugation speed is 6000 r / min and the temperature is 20 °C to obtain a liquid-phase solution.

[0077] S3: Adopt the bubbling contact method with an aeration head to introduce pure CO 2 gas into the liquid-phase solution. The gas flow rate is 0.2 m 3 / h / kg liquid-phase solution, and the temperature is 20 °C to obtain a mixed solution B. The molar ratio of CO 2 contained in the mixed solution B to diethyl 2,6-dimethyl-1,4-dihydro-3,5-pyridinedicarboxylate added in step S1 is 0.1:1.

[0078] S4: Mechanically stir the mixed solution B at a speed of 500 r / min at 20 °C for 2 hours, and then perform intermittent ultrasonic oscillation. The ultrasonic frequency is 20 Hz and the temperature is 20 °C. After each 20-min ultrasonic oscillation, there is an intermittent period of 5 min, and the total duration is 1 hour to obtain a mixed solution C.

[0079] S5: Filter the mixed solution C by suction to remove solid components. The pore size of the filter membrane is 0.22 μm, the suction filtration pressure is 0.1 Pa (absolute pressure), and the temperature is 20 °C to obtain the CO 2 capture absorbent.

[0080] Comparative Example 4 The difference between this comparative example and Example 2 is only that: diethylenetriamine is used as the main absorbent; the remaining steps are the same as those in Example 2. Specifically, the steps for preparing the CO 2 capture absorbent for ship exhaust gas are as follows: S1: Add diethylenetriamine to seawater according to a mass ratio of 3:7, and stir at 70 °C for 30 min to obtain a mixed solution A.

[0081] S2: Centrifuge and filter the mixed solution A to remove solid components. The centrifugation speed is 10000 r / min and the temperature is 20 °C to obtain a liquid-phase solution.

[0082] S3: Adopt the bubbling contact method with an aeration head to introduce pure CO into the liquid-phase solution. 2 The gas flow rate is 0.5 m 3 / h / kg of the liquid-phase solution, and the temperature is 20 °C to obtain the mixed liquid B. The molar ratio of CO contained in the mixed liquid B to the diethylenetriamine added in step S1 is 0.5:1. 2

[0083] S4: Let the mixed liquid B stand still at 20 °C for 2 hours to obtain the mixed liquid C.

[0084] S5: Perform suction filtration on the mixed liquid C to remove the solid components. The pore size of the filter membrane is 0.45 μm, the suction filtration pressure is 10 kPa (absolute pressure), and the temperature is 20 °C to obtain the CO 2 capture absorbent.

[0085] Comparative Example 5 The difference between this comparative example and Example 2 is only that: 2,2,6,6-tetramethylpiperidine is used as the main absorbent; the remaining steps are the same as those in Example 2. Specifically, the steps for preparing the CO 2 capture absorbent for ship exhaust gas are as follows: S1: Add 2,2,6,6-tetramethylpiperidine to seawater according to a mass ratio of 3:7, and stir at 70 °C for 30 min to obtain the mixed liquid A.

[0086] S2: Perform centrifugal filtration on the mixed liquid A to remove the solid components. The centrifugal speed is 10000 r / min, and the temperature is 20 °C to obtain the liquid-phase solution.

[0087] S3: Adopt the bubbling contact method with an aeration head to introduce pure CO into the liquid-phase solution. 2 The gas flow rate is 0.5 m 3 / h / kg of the liquid-phase solution, and the temperature is 20 °C to obtain the mixed liquid B. The molar ratio of CO contained in the mixed liquid B to the 2,2,6,6-tetramethylpiperidine added in step S1 is 0.5:1. 2

[0088] S4: Let the mixed liquid B stand still at 20 °C for 2 hours to obtain the mixed liquid C.

[0089] S5: Perform suction filtration on the mixed liquid C to remove the solid components. The pore size of the filter membrane is 0.45 μm, the suction filtration pressure is 10 kPa (absolute pressure), and the temperature is 20 °C to obtain the CO 2 capture absorbent.

[0090] Comparative Example 6 The difference between this comparative example and Example 3 is only that 2-amino-2-methyl-1-propanol is used as the main absorbent; the remaining steps are the same as those in Example 3. Specifically, the steps for preparing the CO 2 capture absorbent for ship exhaust gas are as follows: S1: Add 2-amino-2-methyl-1-propanol to seawater according to a mass ratio of 3:7, and stir at 20 °C for 30 min to obtain a mixed solution A.

[0091] S2: Centrifuge and filter the mixed solution A to remove solid components. The centrifuge speed is 10000 r / min and the temperature is 20 °C to obtain a liquid-phase solution.

[0092] S3: Adopt a bubble contact method with an aeration head to introduce a mixed gas of CO 2 and N 2 into the liquid-phase solution (where the volume fraction of CO 2 is 10%), the gas flow rate is 2 m 3 / h / kg liquid-phase solution, and the temperature is 20 °C to obtain a mixed solution B. The molar ratio of CO 2 contained in the mixed solution B to 2-amino-2-methyl-1-propanol added in step S1 is 0.5:1.

[0093] S4: Perform intermittent ultrasonic oscillation on the mixed solution B. The ultrasonic frequency is 40 Hz and the temperature is 20 °C. After each ultrasonic oscillation for 30 min, there is an intermittent period of 10 min, and the total duration is 2 hours to obtain a mixed solution C.

[0094] S5: Filter the mixed solution C by suction to remove solid components. The pore size of the filter membrane is 0.45 μm, the suction filtration pressure is 10 kPa (absolute pressure), and the temperature is 20 °C to obtain the CO 2 capture absorbent.

[0095] Comparative Example 7 The difference between this comparative example and Example 3 is only that 1-methyl-4-piperidinol is used as the main absorbent; the remaining steps are the same as those in Example 3. Specifically, the steps for preparing the CO 2 capture absorbent for ship exhaust gas are as follows: S1: Add 1-methyl-4-piperidinol to seawater according to a mass ratio of 3:7, and stir at 20 °C for 30 min to obtain a mixed solution A.

[0096] S2: Centrifuge and filter the mixed solution A to remove solid components. The centrifuge speed is 10000 r / min and the temperature is 20 °C to obtain a liquid-phase solution.

[0097] S3: Adopt a bubble contact method with an aeration head to introduce CO 2 and N 2The mixed gas (where the volume fraction of CO 2 is 10%), the gas flow rate is 2 m 3 / h / kg liquid-phase solution, the temperature is 20 °C, to obtain the mixed liquid B. The molar ratio between the CO 2 contained in the mixed liquid B and the 1-methyl-4-piperidinol added in step S1 is 0.5:1.

[0098] S4: Perform intermittent ultrasonic oscillation on the mixed liquid B, the ultrasonic frequency is 40 Hz, the temperature is 20 °C, each ultrasonic oscillation lasts for 30 min and then there is an intermittent period of 10 min, and the total duration is 2 hours, to obtain the mixed liquid C.

[0099] S5: Perform suction filtration on the mixed liquid C to remove the solid components, the pore size of the filter membrane is 0.45 μm, the suction filtration pressure is 10 kPa (absolute pressure), the temperature is 20 °C, to obtain the CO 2 capturing absorbent.

[0100] Test example Take the CO 2 capturing absorbents prepared in each of the examples and comparative examples, and conduct CO 2 capturing absorption performance tests. The test conditions are as follows: the gas temperature is 40 °C, the CO 2 equilibrium partial pressure (the thermodynamic equilibrium corresponding to the liquid phase of the CO 2 capturing absorbent) is 70 Pa, the gas flow rate is 4 L / min, and the driving force of the partial pressure of the gas-phase CO 2 is 0.5 - 5 kPa (multiple tests are carried out within this range, and the CO 2 absorption rate results are obtained by fitting calculations based on multiple experimental points). The measured CO 2 absorption rate is shown in Table 1.

[0101] Place the prepared absorbent in the degradation experimental device, control the temperature at 65 °C, the pressure is controlled at 0.5 MPa, an O 2 and CO 2 mixed gas (the gas molar concentration ratio is 85%:15%), the stirring speed is 800 r / min, sample and analyze the main agent concentration at the 0th week, 1st week, 2nd week, 3rd week, and 4th week respectively, and test the degradation rate of the absorbent. The absorbent degradation rate measured after 4 weeks is shown in Table 1.

[0102] Table 1 CO 2 Absorption rate and degradation rate test results

[0103] According to the detection results in Table 1, it can be seen that: (1) The CO of Example 1 2The absorption rate is significantly higher than that of Comparative Example 1, indicating that compared with the prior art of using fresh water (deionized water) to prepare the CO 2 capture absorbent, the CO 2 capture absorbent obtained by the method of the present invention can achieve better CO 2 capture absorption effect. The reason for the analysis is as follows: Since seawater contains sodium, potassium ions, chloride ions, sulfate ions, etc., when added to the absorbent, it can increase the polarity of the absorbent system. In the strong polar system of the absorbent main agent of the present invention, due to molecular-ion interaction and hydrogen bond interaction, etc., the molecular activity of the main agent can be improved, thereby increasing the chemical reaction rate.

[0104] (2) When diethyl 2,6-dimethyl-1,4-dihydro-3,5-pyridinedicarboxylate is used as the absorbent main agent in Comparative Example 3, the absorption effect on CO 2 is very weak. The degradation rate of the absorbent main agent in Comparative Example 2 is significantly higher than that in Example 1. It shows that in the absorbent main agent, diethyl 2,6-dimethyl-1,4-dihydro-3,5-pyridinedicarboxylate can improve the stability of hydroxyethyl ethylenediamine, and the compounding of the two can make the CO 2 capture absorbent have better use effect. The reason for the analysis is as follows: The CO 2 absorption capacity of hydroxyethyl ethylenediamine is large, but it is prone to degradation when used alone. When hydroxyethyl ethylenediamine and diethyl 2,6-dimethyl-1,4-dihydro-3,5-pyridinedicarboxylate are compounded and used, the conjugated effect and steric effect generated by diethyl 2,6-dimethyl-1,4-dihydro-3,5-pyridinedicarboxylate can be utilized to capture the active free radicals generated by hydroxyethyl ethylenediamine in the carbon dioxide capture process flow, convert them into stable substances, thereby terminating the free radical chain reaction and improving the degradation problem of hydroxyethyl ethylenediamine.

[0105] (3) The CO 2 absorption rate of Example 2 is higher than that of Comparative Example 5, and the degradation rate is lower than that of Comparative Example 4 and Comparative Example 5, indicating that in the absorbent main agent, a synergistic effect can be generated between diethylenetriamine and 2,2,6,6-tetramethylpiperidine, improving the CO 2 capture absorbent stability and enabling it to have better CO 2 capture absorption capacity. The reason for the analysis is as follows: Diethylenetriamine has strong CO 2 absorption ability, but it is prone to degradation when used alone, while 2,2,6,6-tetramethylpiperidine can improve the degradation problem of diethylenetriamine through conjugated effect and steric effect, and may also have a stabilizing effect on 2,2,6,6-tetramethylpiperidine.

[0106] (4) Compared with Comparative Example 6 and Comparative Example 7, the CO 2The absorption rate is relatively high and the degradation rate is relatively low, indicating that a synergistic effect can be generated between 2-amino-2-methyl-1-propanol and 1-methyl-4-piperidinol in the main absorbent, improving the 2 use effect of the CO capture absorbent. The reason for the analysis is as follows: when 2-amino-2-methyl-1-propanol is used alone, the volatilization loss is relatively large, and the 2 CO absorption and mass transfer rate is relatively slow. After compounding 2-amino-2-methyl-1-propanol with 1-methyl-4-piperidinol, an intermolecular hydrogen bond is formed between the two, which can effectively reduce the volatilization loss of 2-amino-2-methyl-1-propanol. Moreover, 1-methyl-4-piperidinol can also provide a hydrogen proton for the reaction between 2-amino-2-methyl-1-propanol and CO 2 , thereby increasing the 2 CO absorption reaction rate.

[0107] Unless otherwise defined, all technical terms and scientific terms used in the present invention have the same meaning as commonly understood by those of ordinary skill in the art to which the present disclosure belongs. The raw materials and equipment used in the present invention are conventional raw materials and equipment in the art and can be obtained from conventional commercial channels unless otherwise specified; the methods used in the present invention are conventional methods in the art unless otherwise specified.

[0108] The above are only preferred embodiments of the present invention and do not impose any limitation on the present invention. Any simple modification, change, and equivalent transformation made to the above embodiments according to the technical essence of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A method for preparing a carbon dioxide capture absorbent for ship exhaust gas, characterized in that: include: S1: After mixing the absorbent main agent with seawater for reaction, solid-liquid separation is performed to obtain a liquid phase solution; the absorbent main agent includes hydroxyethylethylenediamine and 2,6-dimethyl-1,4-dihydro-3,5-pyridinedicarboxylic acid diethyl ester, or includes diethylenetriamine and 2,2,6,6-tetramethylpiperidine, or includes 2-amino-2-methyl-1-propanol and 1-methyl-4-piperidinol; S2: introducing a carbon dioxide-containing gas into the liquid phase solution, mixing and reacting the solution thoroughly, and then removing the solid components to obtain a carbon dioxide capture absorbent containing an absorbent main agent.

2. The preparation method according to claim 1, characterized in that: In step S1, the mass ratio of hydroxyethylethylenediamine to diethyl 2,6-dimethyl-1,4-dihydro-3,5-pyridinedicarboxylate is 1:0.0019-0.1, the mass ratio of diethylenetriamine to 2,2,6,6-tetramethylpiperidine is 1:0.0033-0.2, and the mass ratio of 2-amino-2-methyl-1-propanol to 1-methyl-4-piperidinol is 1:0.15-1.

6.

3. The preparation method according to claim 1 or 2, characterized in that: In step S1, the mass ratio of the absorbent main agent to seawater is 1:0.25-4.

4. The preparation method according to claim 1, characterized in that: In step S1, the temperature of the mixed reaction is 20-70° C., and the time is 30-120 min.

5. The preparation method according to claim 1, characterized in that: In step S1, the solid-liquid separation method is suction filtration, pressure filtration or centrifugal filtration; the conditions of the suction filtration are: membrane pore size 0.1~0.25μm, absolute pressure 0.1~1kPa, temperature 20~50℃; the conditions of the pressure filtration are: absolute pressure 0.1~1MPa, temperature 20~50℃; the conditions of the centrifugal filtration are: rotation speed 6000~10000r / min, temperature 20~50℃.

6. The preparation method according to claim 1, characterized in that: The molar ratio of the absorbent main agent in step S1 to the carbon dioxide contained in the liquid phase solution after the carbon dioxide-containing gas is introduced in step S2 is 1:0.1-0.

5.

7. The preparation method according to claim 1 or 6, characterized in that: In step S2, the carbon dioxide-containing gas is one or more of pure carbon dioxide gas, ship exhaust gas after desulfurization, and a mixture of carbon dioxide and inert gas; the carbon dioxide-containing gas is introduced into the liquid phase solution by bubbling contact with an aeration head, and the gas flow rate is 0.2-2m 3 / h / kg liquid solution, the temperature is 20~70℃.

8. The preparation method according to claim 1, characterized in that: In step S2, the method of fully mixing and reacting is one or more of stirring, standing, and ultrasonic oscillation; the stirring speed is 500~2000r / min, the temperature is 20~50℃, and the time is 0.5~10h; the standing temperature is 20~50℃, and the time is 0.5~10 hours; the frequency of the ultrasonic oscillation is 20~100Hz, the temperature is 20~50℃, and the total time is 0.5~2h, and each ultrasonication is followed by a rest of 5~10min after 20~50min.

9. The preparation method according to claim 1, characterized in that: In step S2, the method for removing solid components is suction filtration, pressure filtration or centrifugal filtration; the conditions for suction filtration are: membrane pore size 0.2~0.5μm, absolute pressure 0.1~10kPa, temperature 20~50℃; the conditions for pressure filtration are: absolute pressure 0.1~1MPa, temperature 20~50℃; the conditions for centrifugal filtration are: rotation speed 5000~10000r / min, temperature 20~50℃.

10. The use of a carbon dioxide capture absorbent in separating carbon dioxide from ship exhaust gas, characterized in that: The carbon dioxide capture absorbent is prepared by the preparation method according to any one of claims 1 to 9.

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