Preparation method and application of a carbon dioxide capture absorbent for ship exhaust gas

Abstract

The present invention relates to the technical field of carbon dioxide separation from waste gas, and discloses a preparation method and application of a carbon dioxide capture absorbent for ship exhaust gas. The preparation method includes: mixing the absorbent main agent with seawater for reaction, followed by solid-liquid separation 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; introducing carbon dioxide-containing gas into the liquid-phase solution, fully mixing and reacting, and then removing the solid components. By using the method of the present invention, the CO2 capture absorbent can be directly prepared from seawater without using fresh water resources, the energy consumption in the preparation process is low, and the prepared CO2 capture absorbent can be recycled and regenerated when used for separating CO2 in ship exhaust gas, and can achieve a high CO2 capture absorption 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 technical means for ship carbon emission reduction. The chemical absorption process based on the circulation of liquid absorbents is a currently commonly used tail gas carbon dioxide capture technology and has been widely used for the capture of 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, and the absorbent that has absorbed carbon dioxide desorbs carbon dioxide gas at high temperature, thereby realizing the separation of carbon dioxide from the flue gas, and the absorbent that has desorbed 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%), which requires a large amount of fresh water. Since seawater contains a high concentration of inorganic salts, it 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 with 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 cause the absorption effect of carbon dioxide to weaken after operating for a period of time.

[0004] Patent CN114804455A discloses a method for producing alkali and fixing carbon by bipolar membrane electrodialysis coupled with hollow fiber membrane treatment of concentrated seawater. First, the seawater is pretreated by a 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 utilize 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] To solve the above technical problems, that is, the existing method for preparing a CO2 absorbent using seawater has high energy consumption, and the prepared CO2 absorbent cannot be recycled, which is not conducive to large-scale application and long-term operation on ships. The present invention provides a method for preparing and applying a carbon dioxide capture absorbent for ship exhaust gas. By using the method of the present invention, a CO2 capture absorbent can be directly prepared from seawater without using fresh water resources, the energy consumption in the preparation process is low, and the prepared CO2 capture absorbent can be recycled when used to separate CO2 in ship exhaust gas, and a relatively high CO2 capture and absorption efficiency can be achieved.

[0006] The specific technical solution of the present invention is as follows:

[0007] In the first aspect, the present invention provides a method for preparing a carbon dioxide capture absorbent for ship exhaust gas, comprising:

[0008] 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;

[0009] S2: Carbon dioxide-containing gas is introduced into the liquid-phase solution, and after sufficient mixing and reaction, the solid components are removed to obtain a carbon dioxide capture absorbent containing the absorbent main agent.

[0010] In the present invention, specific absorbent main agents are used to react with magnesium ions and calcium ions in seawater and CO2 in the CO2-containing gas in sequence to form precipitates, and after removing these precipitates, a CO2 capture absorbent is obtained. The specific process is as follows:

[0011] (1) In step S1, when seawater is mixed with the absorbent main agent, the following reaction can occur:

[0012] A + H2O ↔ AH + + OH - (Absorbent main agent-water balance reaction ①);

[0013] 2 A + H2O + Mg 2+ → 2 AH + + Mg(OH)2;

[0014] Wherein, A represents the absorbent main agent, AH + is the protonated absorbent main agent, and Mg(OH)2 is the precipitate.

[0015] (2) In step S2, after introducing CO2, the following reaction can occur:

[0016] 2A + H2O + CO2 → AH + + ACOO - (Main reaction of the absorbent main agent with CO2);

[0017] A + H2O + CO2 → AH + + HCO3 - ;

[0018] ACOO - + H2O ↔ AH + + HCO3 - (Equilibrium reaction ②);

[0019] A + HCO3 - ↔ AH + + CO3 2- (Equilibrium reaction ③);

[0020] Ca 2+ + CO3 2- → CaCO3 (Reaction involving calcium ions in seawater);

[0021] Among them, ACOO - is the carbamate ion, and CaCO3 is the precipitate;

[0022] In the above process, as the precipitation reaction occurs, the equilibrium reaction ③ shifts to the right, consuming HCO3 - , which in turn causes the equilibrium reaction ② to shift to the right until all the calcium ions in the seawater are precipitated and a new equilibrium is reached.

[0023] In the CO2 capture absorbent prepared by the above method, the absorbent main agent contained therein can capture and absorb CO2, thus being used for the separation of CO2 in ship exhaust gas. Moreover, in the process of preparing the CO2 capture absorbent of the present invention, magnesium ions and calcium ions in seawater can be removed, avoiding blockage of the carbon dioxide capture system caused by precipitates formed by magnesium ions and calcium ions when using the CO2 capture absorbent to separate CO2 in ship exhaust gas.

[0024] Using the method of the present invention to prepare a CO2 capture absorbent has the following advantages: 1) The present invention can directly utilize seawater to prepare a CO2 capture absorbent without using the fresh water resources on the ship and without the need for complex operations to desalinate seawater or perform bipolar membrane electrodialysis to produce alkali. 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 the ship; 2) Compared with using fresh water to prepare a CO2 capture absorbent, the CO2 capture absorbent prepared by the method of the present invention has better CO2 capture and absorption 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 CO2; 3) When the CO2 capture absorbent prepared by the present invention is used for the separation of CO2 in ship exhaust gas, CO2 can be desorbed by heating after absorbing CO2, realizing the cyclic regeneration of the CO2 capture absorbent; 4) Using the method of the present invention to prepare a CO2 capture absorbent can also reduce the equipment size. Taking the preparation of 1 ton of CO2 capture absorbent containing 30 wt% absorbent main agent and 70 wt% water as an example, when using the conventional method (using fresh water to prepare), an absorbent storage tank of about 1 m 3 is required on the ship, while using the method of the present invention, only 300 kg of absorbent main agent needs to be stored, and the storage tank size is about 0.3 m 3 , which can greatly reduce the equipment footprint and thus save space for the ship.

[0025] In addition, the present invention specially designs the formula of the absorbent main agent, which can improve the CO2 capture and absorption effect of the CO2 capture absorbent on the CO2 in ship exhaust gas:

[0026] (1) Hydroxyethyl ethylenediamine and diethyl 2,6-dimethyl-1,4-dihydro-3,5-pyridinedicarboxylate: Hydroxyethyl ethylenediamine has a large CO2 absorption capacity, 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, convert them into stable substances, thereby terminating the free radical chain reaction, improving the degradation problem of hydroxyethyl ethylenediamine, and thus improving the CO2 capture and absorption efficiency of the CO2 capture absorbent during use and enhancing its stability during long-term operation.

[0027] (2) Diethylenetriamine and 2,2,6,6 - tetramethylpiperidine: Similar to the coordination mechanism between hydroxyethyl ethylenediamine and diethyl 2,6 - dimethyl - 1,4 - dihydropyridine - 3,5 - dicarboxylate, diethylenetriamine has strong CO2 absorption capacity, but it is prone to degradation when used alone. While 2,2,6,6 - tetramethylpiperidine can improve the degradation problem of diethylenetriamine through conjugate effect and steric effect, thereby enhancing the CO2 capture and absorption efficiency and the long - term operation stability of the CO2 capture absorbent.

[0028] (3) 2 - Amino - 2 - methyl - 1 - propanol and 1 - methyl - 4 - piperidinol: When 2 - amino - 2 - methyl - 1 - propanol is used alone, the volatilization loss is large and the CO2 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 CO2. Therefore, it can improve the CO2 absorption reaction rate and the long - term operation stability of the CO2 capture absorbent.

[0029] Preferably, in step S1, the mass ratio of hydroxyethyl ethylenediamine to diethyl 2,6 - dimethyl - 1,4 - dihydropyridine - 3,5 - dicarboxylate 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.

[0030] Under the above ratios, good pairwise synergistic effects can be generated between the main absorbent components, thereby achieving higher CO2 capture and absorption efficiency and long - term operation stability.

[0031] Preferably, in step S1, the mass ratio of the main absorbent to seawater is 1:0.25 - 4.

[0032] Preferably, in step S1, the temperature of the mixing reaction is 20 - 70 °C and the time is 30 - 120 min.

[0033] Preferably, in step S1, the solid - liquid separation method is suction filtration, pressure filtration or centrifugal filtration; the conditions for suction filtration are: filter membrane pore size 0.1 - 0.25 μm, absolute pressure 0.1 - 1 kPa, temperature 20 - 50 °C; the conditions for pressure filtration are: absolute pressure 0.1 - 1 MPa, temperature 20 - 50 °C; the conditions for centrifugal filtration are: rotational speed 6000 - 10000 r / min, temperature 20 - 50 °C.

[0034] Preferably, the molar ratio between the absorbent main agent in step S1 and the carbon dioxide contained in the liquid-phase solution after introducing the carbon dioxide-containing gas in step S2 is 1:0.1 to 0.5.

[0035] 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 to 2 m 3 / h / kg liquid-phase solution, and the temperature is 20 to 70 °C.

[0036] Preferably, in step S2, the method of sufficient mixing and reaction is one or more of stirring, standing still, and ultrasonic oscillation; the rotation speed of the stirring is 500 to 2000 r / min, the temperature is 20 to 50 °C, and the time is 0.5 to 10 h; the temperature of the standing still is 20 to 50 °C, and the time is 0.5 to 10 hours; the frequency of the ultrasonic oscillation is 20 to 100 Hz, the temperature is 20 to 50 °C, the total duration is 0.5 to 2 h, and there is an intermittent period of 5 to 10 min after each ultrasonic treatment for 20 to 50 min.

[0037] Preferably, in step S2, the method of removing the solid components is suction filtration, pressure filtration, or centrifugal filtration; the conditions for the suction filtration are: the pore size of the filter membrane is 0.2 to 0.5 μm, the absolute pressure is 0.1 to 10 kPa, and the temperature is 20 to 50 °C; the conditions for the pressure filtration are: the absolute pressure is 0.1 to 1 MPa, and the temperature is 20 to 50 °C; the conditions for the centrifugal filtration are: the rotation speed is 5000 to 10000 r / min, and the temperature is 20 to 50 °C.

[0038] In the second aspect, the present invention provides an application of the 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.

[0039] Compared with the prior art, the present invention has the following advantages:

[0040] (1) By using the method of the present invention, it is possible to directly prepare a CO2 capture absorbent from seawater, avoiding the blockage of the carbon dioxide capture system caused by the precipitation of calcium ions and magnesium ions existing in seawater. During the whole preparation process of the CO2 capture absorbent, fresh water resources are not required, and the energy consumption is relatively low. The prepared CO2 capture absorbent has good capture and absorption ability for CO2 during use and can be recycled, which is beneficial to large-scale application and long-term operation on ships.

[0041] (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, and 2-amino-2-methyl-1-propanol and 1-methyl-4-piperidinol can produce a good coordination effect, so that the prepared CO2 capture absorbent has a higher CO2 capture and absorption efficiency when used, and has better stability in long-term operation. DETAILED DESCRIPTION

[0042] The present invention will be further described below in conjunction with the embodiments.

[0043] A method for preparing a carbon dioxide capture absorbent for ship exhaust gas, comprising:

[0044] 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;

[0045] 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.

[0046] 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.

[0047] In some specific embodiments, in step S1, the mass ratio of the absorbent main agent to seawater is 1:0.25~4.

[0048] In some specific embodiments, in step S1, the temperature of the mixing reaction is 20-70° C., and the time is 30-120 min.

[0049] 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 pore size of the filter membrane 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.

[0050] In some specific embodiments, the molar ratio between the absorbent main agent in step S1 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.

[0051] 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.

[0052] In some specific embodiments, in step S2, the carbon dioxide-containing gas is introduced into the liquid-phase solution by means of bubbling 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.

[0053] In some specific embodiments, 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 after each ultrasonic treatment for 20-50 min, there is an intermittent period of 5-10 min.

[0054] 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 pore size of the filter membrane 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.

[0055] 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 preparation method described above.

[0056] 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 scope of protection of the present invention is defined by the appended claims and any equivalents thereof.

[0057] Example 1

[0058] The CO2 capture absorbent for ship exhaust gas was prepared according to the following steps:

[0059] S1: Using 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, adding the main absorbent to seawater according to a mass ratio of 3:7, and stirring at 20 °C for 120 min to obtain a mixed solution A.

[0060] S2: Centrifugally filter the mixed solution A to remove solid components. The centrifugal speed is 6000 r / min and the temperature is 20 °C to obtain a liquid-phase solution.

[0061] S3: Using a bubbling contact method with an aeration head, pure CO2 gas is introduced 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 CO2 contained in the mixed solution B to the main absorbent added in step S1 is 0.1:1.

[0062] 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.

[0063] 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 CO2 capture absorbent.

[0064] Example 2

[0065] The CO2 capture absorbent for ship exhaust gas was prepared according to the following steps:

[0066] S1: Using diethylenetriamine and 2,2,6,6-tetramethylpiperidine with a mass ratio of 1:0.2 as the main absorbent, adding the main absorbent to seawater according to a mass ratio of 3:7, and stirring at 70 °C for 30 min to obtain a mixed solution A.

[0067] 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.

[0068] S3: Adopt the bubble contact method with an aeration head to introduce pure CO2 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. The molar ratio of CO2 contained in the mixture B to the absorbent main agent added in step S1 is 0.5:1.

[0069] S4: Let the mixture B stand for 2 hours at 20 °C to obtain a mixture C.

[0070] S5: Filter the mixture 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 a CO2 capture absorbent.

[0071] Example 3

[0072] Prepare a CO2 capture absorbent for ship exhaust gas according to the following steps:

[0073] 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.

[0074] 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.

[0075] S3: Adopt the bubble contact method with an aeration head to introduce a mixture of CO2 and N2 (where the volume fraction of CO2 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. The molar ratio of CO2 contained in the mixture B to the absorbent main agent added in step S1 is 0.5:1.

[0076] 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.

[0077] S5: Filter the mixture 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 a CO2 capture absorbent.

[0078] Example 4

[0079] Prepare a CO₂ capture absorbent for ship exhaust gas according to the following steps:

[0080] S1: Use hydroxyethyl ethylenediamine and diethyl 2,6-dimethyl-1,4-dihydro-3,5-pyridinedicarboxylate 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 a mixed solution A.

[0081] 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.

[0082] S3: Adopt the bubbling contact method with an aeration head to introduce a mixed gas of CO₂ and N₂ (where the volume fraction of CO₂ is 10%) into the liquid-phase solution. 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 CO₂ contained in the mixed solution B to the main absorbent added in step S1 is 0.2:1.

[0083] S4: Mechanically stir the mixed solution B at a speed of 2000 r / min for 2 hours at 20 °C, then let it stand for 10 hours at 20 °C, 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 a mixed solution C.

[0084] S5: Centrifuge and filter the mixed solution C to remove solid components. The centrifuge speed is 8000 r / min and the temperature is 20 °C to obtain a CO₂ capture absorbent.

[0085] Example 5

[0086] Prepare a CO₂ capture absorbent for ship exhaust gas according to the following steps:

[0087] 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 a mixed solution A.

[0088] 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.

[0089] S3: Adopt the bubbling contact method with an aeration head to introduce pure CO₂ gas into the liquid-phase solution. The gas flow rate is 0.5 m 3A liquid phase solution of / h / kg, at a temperature of 20 °C, to obtain a mixed solution B. The molar ratio of CO₂ contained in the mixed solution B to the absorbent main agent added in step S1 is 0.5:1.

[0090] S4: Leave the mixed solution B to stand at 20 °C for 2 hours to obtain a mixed solution C.

[0091] S5: Filter the mixed solution 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 CO₂ capture absorbent.

[0092] Example 6

[0093] Prepare a CO₂ capture absorbent for ship exhaust gas according to the following steps:

[0094] 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. 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 mixed solution A.

[0095] S2: Centrifuge and filter the mixed solution A to remove the solid components. The centrifuge speed is 10000 r / min and the temperature is 20 °C to obtain a liquid phase solution.

[0096] S3: Adopt a bubbling contact method with an aeration head to introduce a mixed gas of CO₂ and N₂ (where the volume fraction of CO₂ is 10%) into the liquid phase solution. The gas flow rate is 2 m 3 / h / kg liquid phase solution, at a temperature of 20 °C, to obtain a mixed solution B. The molar ratio of CO₂ contained in the mixed solution B to the absorbent main agent added in step S1 is 0.5:1.

[0097] S4: Perform intermittent ultrasonic oscillation on the mixed solution B. The ultrasonic frequency is 40 Hz and the temperature is 20 °C. Each ultrasonic oscillation lasts for 30 min and then there is an intermittent period of 10 min. The total duration is 2 hours to obtain a mixed solution C.

[0098] S5: Filter the mixed solution 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 CO₂ capture absorbent.

[0099] Comparative Example 1

[0100] This comparative example uses deionized water to prepare a CO₂ capture absorbent. Specifically, the steps for preparing a CO₂ capture absorbent for ship exhaust gas in this comparative example are as follows:

[0101] Using hydroxyethyl ethylenediamine and diethyl 2,6-dimethyl-1,4-dihydro-3,5-pyridinedicarboxylate with a mass ratio of 1:0.0019 as the main absorbents, adding the main absorbents to deionized water according to a mass ratio of 3:7, and stirring at 25 °C for 60 min to obtain a CO2 capture absorbent.

[0102] Comparative Example 2

[0103] 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 CO2 capture absorbent for ship exhaust gas in this comparative example are as follows:

[0104] S1: Adding hydroxyethyl ethylenediamine to seawater according to a mass ratio of 3:7, and stirring at 20 °C for 120 min to obtain a mixed solution A.

[0105] S2: Centrifugally filtering the mixed solution A to remove solid components, with a centrifugal speed of 6000 r / min and a temperature of 20 °C, to obtain a liquid-phase solution.

[0106] S3: Using a bubbling contact method with an aeration head, introducing pure CO2 gas into the liquid-phase solution, with a gas flow rate of 0.2 m 3 / h / kg liquid-phase solution and a temperature of 20 °C to obtain a mixed solution B, and the molar ratio of CO2 contained in the mixed solution B to the hydroxyethyl ethylenediamine added in step S1 is 0.1:1.

[0107] S4: Mechanically stirring the mixed solution B at a speed of 500 r / min at 20 °C for 2 hours, then performing intermittent ultrasonic oscillation, with an ultrasonic frequency of 20 Hz and a temperature of 20 °C, oscillating for 20 min each time and then pausing for 5 min, with a total duration of 1 hour, to obtain a mixed solution C.

[0108] S5: Filtering the mixed solution C by suction to remove solid components, with a filter membrane pore size of 0.22 μm, a suction filtration pressure of 0.1 Pa (absolute pressure), and a temperature of 20 °C, to obtain a CO2 capture absorbent.

[0109] Comparative Example 3

[0110] 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 CO2 capture absorbent for ship exhaust gas in this comparative example are as follows:

[0111] S1: Adding diethyl 2,6-dimethyl-1,4-dihydro-3,5-pyridinedicarboxylate to seawater according to a mass ratio of 3:7, and stirring at 20 °C for 120 min to obtain a mixed solution A.

[0112] S2: Centrifuge and filter the mixture A to remove solid components at a centrifuge speed of 6000 r / min and a temperature of 20 °C to obtain a liquid-phase solution.

[0113] S3: Adopt the bubbling contact method with an aeration head to introduce pure CO2 gas into the liquid-phase solution at a gas flow rate of 0.2 m 3 / h / kg liquid-phase solution and a temperature of 20 °C to obtain a mixture B. The molar ratio of CO2 contained in the mixture B to diethyl 2,6-dimethyl-1,4-dihydro-3,5-pyridinedicarboxylate added in step S1 is 0.1:1.

[0114] S4: Mechanically stir the mixture B at a speed of 500 r / min for 2 hours at 20 °C, 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 a 5-min interval, and the total duration is 1 hour to obtain a mixture C.

[0115] S5: Filter the mixture 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 CO2 capture absorbent.

[0116] Comparative Example 4

[0117] 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 CO2 capture absorbent for ship exhaust gas in this comparative example are as follows:

[0118] S1: Add diethylenetriamine to seawater according to a mass ratio of 3:7, and stir at 70 °C for 30 min to obtain a mixture A.

[0119] S2: Centrifuge and filter the mixture A to remove solid components at a centrifuge speed of 10000 r / min and a temperature of 20 °C to obtain a liquid-phase solution.

[0120] S3: Adopt the bubbling contact method with an aeration head to introduce pure CO2 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. The molar ratio of CO2 contained in the mixture B to diethylenetriamine added in step S1 is 0.5:1.

[0121] S4: Let the mixture B stand at 20 °C for 2 hours to obtain a mixture C.

[0122] S5: Filter the mixture 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 a CO2 capture absorbent.

[0123] Comparative Example 5

[0124] 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 CO2 capture absorbent for ship exhaust gas in this comparative example are as follows:

[0125] 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 a mixed solution A.

[0126] 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.

[0127] S3: Adopt the bubbling contact method with an aeration head, and introduce pure CO2 gas into the liquid-phase solution. The gas flow rate is 0.5 m 3 / h / kg liquid-phase solution, and the temperature is 20 °C to obtain a mixed solution B. The molar ratio of CO2 contained in the mixed solution B to 2,2,6,6-tetramethylpiperidine added in step S1 is 0.5:1.

[0128] S4: Let the mixed solution B stand at 20 °C for 2 hours to obtain a mixed solution C.

[0129] 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 pressure is 10 kPa (absolute pressure), and the temperature is 20 °C to obtain the CO2 capture absorbent.

[0130] Comparative Example 6

[0131] 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 CO2 capture absorbent for ship exhaust gas in this comparative example are as follows:

[0132] 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.

[0133] 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.

[0134] S3: Adopt the bubbling contact method with an aeration head, and introduce a mixed gas of CO2 and N2 (where the volume fraction of CO2 is 10%) into the liquid-phase solution. The gas flow rate is 2 m 3 / h / kg liquid phase solution at a temperature of 20 °C to obtain a mixed liquid B, and the molar ratio of CO2 contained in the mixed liquid B to 2-amino-2-methyl-1-propanol added in step S1 is 0.5:1.

[0135] S4: Perform intermittent ultrasonic oscillation on the mixed liquid B, with an ultrasonic frequency of 40 Hz and a temperature of 20 °C. After each 30-minute ultrasonic oscillation, there is an intermittent period of 10 minutes, and the total duration is 2 hours to obtain a mixed liquid C.

[0136] S5: Perform suction filtration on the mixed liquid C 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 a CO2 capture absorbent.

[0137] Comparative Example 7

[0138] 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 CO2 capture absorbent for ship exhaust gas in this comparative example are as follows:

[0139] S1: Add 1-methyl-4-piperidinol to seawater according to a mass ratio of 3:7, and stir at 20 °C for 30 minutes to obtain a mixed liquid A.

[0140] S2: Perform centrifugal filtration on the mixed liquid A to remove solid components. The centrifugal speed is 10,000 r / min and the temperature is 20 °C to obtain a liquid phase solution.

[0141] S3: Adopt a bubbling contact method with an aeration head to introduce a mixed gas of CO2 and N2 (where the volume fraction of CO2 is 10%) into the liquid phase solution, and the gas flow rate is 2 m 3 / h / kg liquid phase solution at a temperature of 20 °C to obtain a mixed liquid B, and the molar ratio of CO2 contained in the mixed liquid B to 1-methyl-4-piperidinol added in step S1 is 0.5:1.

[0142] S4: Perform intermittent ultrasonic oscillation on the mixed liquid B, with an ultrasonic frequency of 40 Hz and a temperature of 20 °C. After each 30-minute ultrasonic oscillation, there is an intermittent period of 10 minutes, and the total duration is 2 hours to obtain a mixed liquid C.

[0143] S5: Perform suction filtration on the mixed liquid C 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 a CO2 capture absorbent.

[0144] Test Example

[0145] Take the CO2 capture absorbents prepared in each example and comparative example, and conduct CO2 capture absorption performance tests. The test conditions are as follows: the gas temperature is 40 °C, the CO2 equilibrium partial pressure (the corresponding thermodynamic equilibrium of the CO2 capture absorbent liquid phase) is 70 Pa, the gas flow rate is 4 L / min, and the driving force of the CO2 partial pressure in the gas phase is 0.5 - 5 kPa (multiple tests are carried out within this range, and the CO2 absorption rate results are obtained by fitting calculations based on multiple experimental points). The measured CO2 absorption rates are shown in Table 1.

[0146] Place the prepared absorbent in a degradation experimental device, control the temperature at 65 °C, the pressure at 0.5 MPa, an O2 and CO2 mixed gas (the molar concentration ratio of the gas is 85%:15%), and the stirring speed at 800 r / min. Samples are taken at the 0th week, 1st week, 2nd week, 3rd week, and 4th week respectively to analyze the main agent concentration and test the degradation rate of the absorbent. The absorbent degradation rates measured after 4 weeks are shown in Table 1.

[0147] Table 1 Test results of CO2 absorption rate and degradation rate

[0148]

[0149] According to the test results in Table 1, it can be seen that:

[0150] (1) The CO2 absorption rate of Example 1 is significantly higher than that of Comparative Example 1, indicating that compared with the existing technology of using fresh water (deionized water) to prepare CO2 capture absorbents, the CO2 capture absorbent obtained by the method of the present invention can achieve better CO2 capture absorption effects. The reason for the analysis is that 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 a strong polar system, due to molecular-ion interactions and hydrogen bond interactions, etc., the molecular activity of the main agent of the absorbent of the present invention can be improved, thereby increasing the chemical reaction rate.

[0151] (2) When diethyl 2,6-dimethyl-1,4-dihydro-3,5-pyridinedicarboxylate was used as the main absorbent in Comparative Example 3, the absorption effect on CO2 was very weak. The degradation rate of the main absorbent in Comparative Example 2 was significantly higher than that in Example 1. It shows that in the main absorbent, diethyl 2,6-dimethyl-1,4-dihydro-3,5-pyridinedicarboxylate can improve the stability of aminoethylethanolamine, and the compounding of the two can make the CO2 capture absorbent have better use effect. The reason for the analysis is as follows: Aminoethylethanolamine has a large CO2 absorption capacity, but it is prone to degradation when used alone. When aminoethylethanolamine 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 aminoethylethanolamine in the carbon dioxide capture process flow, and convert them into stable substances, thereby terminating the free radical chain reaction and improving the degradation problem of aminoethylethanolamine.

[0152] (3) The CO2 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 main absorbent, a synergistic effect can be generated between diethylenetriamine and 2,2,6,6-tetramethylpiperidine, improving the stability of the CO2 capture absorbent and endowing it with better CO2 capture and absorption capacity. The reason for the analysis is as follows: Diethylenetriamine has a strong CO2 absorption capacity, but it is prone to degradation when used alone. 2,2,6,6-Tetramethylpiperidine can improve the degradation problem of diethylenetriamine through the conjugated effect and steric effect, and may also have a stabilizing effect on 2,2,6,6-tetramethylpiperidine at the same time.

[0153] (4) Compared with Comparative Example 6 and Comparative Example 7, the CO2 absorption rate of Example 3 is higher and the degradation rate is lower, indicating that in the main absorbent, a synergistic effect can be generated between 2-amino-2-methyl-1-propanol and 1-methyl-4-piperidinol, improving the use effect of the CO2 capture absorbent. The reason for the analysis is as follows: When 2-amino-2-methyl-1-propanol is used alone, the volatilization loss is large and the CO2 absorption mass transfer rate is slow. After compounding 2-amino-2-methyl-1-propanol and 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, and 1-methyl-4-piperidinol can also provide hydrogen protons for the reaction between 2-amino-2-methyl-1-propanol and CO2, thereby increasing the CO2 absorption reaction rate.

[0154] Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. The raw materials and equipment used in this 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 this invention are conventional methods in the art unless otherwise specified.

[0155] As described above, the above are only the preferred embodiments of the present invention and do not impose any limitation on the present invention. Any simple modifications, changes, and equivalent transformations made to the above embodiments based on the technical essence of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A preparation method of a carbon dioxide capture absorbent for ship exhaust gas, characterized in that, Including: S1: After mixing and reacting the absorbent main agent with seawater, 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: Pass a carbon dioxide-containing gas into the liquid-phase solution. After sufficient mixing and reaction, solid components are removed to obtain a carbon dioxide capture absorbent containing the absorbent main agent.

2. The preparation method according to claim 1, characterized in that, 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.

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, wherein, In step S1, the temperature of the mixing 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 method of solid-liquid separation 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.

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 passing the carbon dioxide-containing gas 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, 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.

8. The preparation method according to claim 1, characterized in that, In step S2, the method of sufficient mixing and reaction is one or more of stirring, standing, and ultrasonic oscillation; the rotation speed of 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 h; the frequency of 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.

9. The preparation method according to claim 1, wherein 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.

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

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