A method and device for capturing and fixing carbon dioxide in ship exhaust

Abstract

The present invention relates to the field of carbon dioxide separation technology, and discloses a method and apparatus for capturing and fixing carbon dioxide from ship exhaust. The method comprises the following steps: passing seawater, an amine catalyst, and ship exhaust gas into a CO2 capture tower to complete a CO2 absorption reaction, discharging decarbonized exhaust gas and a mixed liquid I; passing the mixed liquid I into a CO2 fixation reactor to complete a CO2 fixation precipitation reaction, followed by solid-liquid separation, and discharging a CO2 fixation product and a mixed liquid II; passing the mixed liquid II into a catalyst regenerator to complete a catalyst regeneration reaction, followed by solid-liquid separation, discharging a CO2 fixation product and a mixed liquid III, and concentrating the mixed liquid III for reuse in S1. The method of the present invention can reduce the regeneration energy consumption of the amine catalyst, and the CO2 is directly fixed to form a solid-phase product after capture, eliminating the subsequent CO2 compression, liquefaction, and tank storage processes, thereby reducing the device footprint.

Description

Technical Field

[0001] The present invention relates to the technical field of carbon dioxide separation, and in particular to a method and device for capturing and fixing carbon dioxide in ship exhaust gas. Background Art

[0002] The shipping industry is a significant source of CO2 emissions, particularly ocean-going vessels that rely primarily on fossil fuels such as heavy oil. Capturing CO2 from ship exhaust is a key technological approach to reducing carbon emissions. Currently, chemical absorption is the most common process for capturing CO2 from ship exhaust. This technology utilizes an alkaline absorbent to react with CO2 to produce an acid-base neutralization reaction, thereby separating the CO2 from the exhaust. CO2 capture processes can be categorized as either cyclic or non-cyclic, depending on whether the alkaline absorbent is recycled in the CO2 capture process.

[0003] Non-cyclic absorption processes generally use strongly alkaline absorbents, which undergo an irreversible reaction with CO2 in ship exhaust. Since the absorbent is non-renewable, this results in high costs for carbon capture from ship exhaust. In comparison, cyclic absorption processes typically use regenerative weakly alkaline organic amine absorbents, which undergo a reversible reaction with CO2. The carbon dioxide is then desorbed by heating, allowing the absorbent to be regenerated (e.g., patent CN113828120A). This approach can reduce absorbent costs, but it also suffers from high energy consumption for absorbent regeneration. Furthermore, the captured CO2 is not fixed, and the separated gaseous CO2 requires additional equipment for compression, liquefaction, and storage, resulting in a large footprint for the entire device and limiting its application on ships. Summary of the Invention

[0004] To address the technical issues mentioned above, namely, the high energy consumption of absorbent regeneration in existing carbon dioxide cyclic absorption processes, the unfixed capture of carbon dioxide, and the need for additional CO2 compression and liquefaction equipment and CO2 storage tanks, the present invention provides a method and apparatus for capturing and fixing carbon dioxide from ship exhaust. This method reduces the regeneration energy consumption of amine catalysts, and the CO2 is directly fixed to form a solid product after capture, eliminating the subsequent CO2 compression, liquefaction, and tank storage processes, thereby reducing the equipment footprint.

[0005] The specific technical solutions of the present invention are:

[0006] In a first aspect, the present invention provides a method for capturing and fixing carbon dioxide in ship exhaust, comprising the following steps:

[0007] S1: Pass seawater, amine catalyst and ship exhaust gas into the CO2 capture tower to complete the CO2 absorption reaction and discharge the decarbonized exhaust gas and mixed liquid I; the CO2 absorption reaction includes:

[0008] ,

[0009] ,

[0010] ,

[0011] Among them, CA is an amine catalyst;

[0012] S2: The mixed solution I is introduced into the CO2 fixation reactor. After the CO2 fixation precipitation reaction is completed, the solid and liquid are separated, and the CO2 fixation product and the mixed solution II are discharged. The CO2 fixation precipitation reaction includes:

[0013] ,

[0014] ;

[0015] S3: The mixed liquid II is passed into the catalyst regenerator. After the catalyst regeneration reaction is completed, the solid and liquid are separated, and the CO2 fixed product and the mixed liquid III are discharged. The mixed liquid III is concentrated and then reused in S1. The catalyst regeneration reaction includes:

[0016] ,

[0017] .

[0018] The principles of capturing and fixing carbon dioxide in the present invention are as follows:

[0019] (1) First, under the action of the amine catalyst, CO2 is absorbed by the mixture of seawater and the amine catalyst through the CO2 absorption reaction. The above CO2 absorption reaction is as follows:

[0020] ;

[0021] ;

[0022] .

[0023] (2) Under the action of calcium ions and magnesium ions in seawater, CO2 is absorbed by the mixture of seawater and amine catalysts to form CO3 2− The CO2 fixation precipitation reaction occurs and is converted into precipitate. The above CO2 fixation precipitation reaction is as follows:

[0024] ;

[0025] .

[0026] (3) Through the catalyst regeneration reaction, the amine catalyst can be regenerated after absorbing CO2. At the same time, the released carbon-containing substances are precipitated under the action of calcium ions and magnesium ions in seawater. The above catalyst regeneration reaction is as follows:

[0027] ;

[0028] .

[0029] In the above process, the CO2 absorption reaction is completed in the CO2 capture tower. At the same time, the CO2 capture tower will also undergo partial CO2 fixation precipitation reaction; in the CO2 fixation reactor, the CO2 fixation precipitation reaction will be completed, and at the same time, partial catalyst regeneration reaction will occur, and the CO2 fixation products (CaCO3 and MgCO3) can be separated through solid-liquid separation; in the catalyst regenerator, the catalyst regeneration reaction will be completed, and the CO2 fixation products (CaCO3 and MgCO3) can be separated through solid-liquid separation.

[0030] Through the above method, the present invention can directly use seawater to capture and fix carbon dioxide in ship exhaust gas, without consuming freshwater resources on the ship or performing a complex desalination process on the seawater; moreover, after being captured, CO2 is directly fixed to form solid-phase products (CaCO3 and MgCO3), which can save the subsequent CO2 compression, liquefaction, and tank storage processes, thereby reducing the footprint of the entire device and lowering energy consumption, making it particularly suitable for ship conditions; in addition, through the process of the present invention, the recycling of amine catalysts can be achieved, thereby enabling the entire device to operate for a long period of time and reducing catalyst costs, and the present invention utilizes calcium ions and magnesium ions in seawater to regenerate the amine catalyst, which can reduce the energy consumption of catalyst regeneration.

[0031] In addition, the present invention separates the CO2 absorption reaction, CO2 fixation precipitation reaction and catalyst regeneration reaction into three reaction devices (CO2 capture tower, CO2 fixation reactor and catalyst regenerator). This design has the following effects: the CO2 absorption reaction is an exothermic reaction, which easily increases the temperature in the CO2 capture tower, and the temperature at the top of the CO2 capture tower may reach a relatively high level. Separating the CO2 fixation precipitation reaction and the catalyst regeneration reaction from the CO2 absorption reaction and carrying them out in different devices is beneficial to temperature control during the CO2 fixation precipitation reaction and the catalyst regeneration reaction, thereby promoting the progress of these two reactions.

[0032] Preferably, in step S1, the amine catalyst is the following a) or b):

[0033] a) comprising diethylenetriamine and 2,2,6,6-tetramethylpiperidine in a mass ratio of 1:0.0033-0.2;

[0034] b) comprising 2-amino-2-methyl-1-propanol and 1-methyl-4-piperidinol in a mass ratio of 1:0.15-1.6.

[0035] Both amine catalysts a) and b) are liquid-phase catalysts, enabling homogeneous catalysis and high CO2 capture efficiency. Furthermore, the two amine catalysts a) and b) are each formulated with two specific components, which, when combined in the present invention, produce a synergistic effect, enhancing the catalytic effect. The specific mechanism is as follows:

[0036] In step a), by combining diethylenetriamine and 2,2,6,6-tetramethylpiperidine in a mass ratio of 1:0.0033-0.2, diethylenetriamine can achieve higher CO2 capture efficiency. Simultaneously, the conjugation and steric effects between diethylenetriamine and 2,2,6,6-tetramethylpiperidine enhance their stability. This approach achieves higher CO2 capture efficiency and reduces degradation and loss of the amine catalyst during long-term operation.

[0037] In step b), by compounding 2-amino-2-methyl-1-propanol and 1-methyl-4-piperidinol in a mass ratio of 1:0.15-1.6, the intermolecular hydrogen bonding between the two components can be utilized to reduce the volatilization loss of 2-amino-2-methyl-1-propanol. At the same time, 1-methyl-4-piperidinol can provide hydrogen protons for the reaction between 2-amino-2-methyl-1-propanol and CO2, thereby improving the CO2 capture efficiency. In this way, 2-amino-2-methyl-1-propanol and 1-methyl-4-piperidinol can synergistically improve the CO2 capture efficiency and reduce the loss of amine catalysts during long-term operation.

[0038] Preferably, in step S1, the CO2 capture tower is a packed tower, a plate tower or a hollow fiber membrane contactor.

[0039] Preferably, in step S1, the operating temperature of the CO2 capture tower is 20-80°C.

[0040] Preferably, in step S2, the operating temperature of the CO2 fixation reactor is 20-50°C.

[0041] Preferably, in step S3, the operating temperature of the catalyst regenerator is 20-50°C.

[0042] Preferably, in step S1, the specific process of passing seawater, amine catalyst and ship exhaust gas into the CO2 capture tower includes: mixing seawater and amine catalyst in a mass ratio of 1:0.05~4, passing the obtained mixture of seawater and amine catalyst into the CO2 capture tower, and simultaneously passing ship exhaust gas into the CO2 capture tower.

[0043] Preferably, in step S1, the flow rate of the mixture of seawater and amine catalyst and the ship exhaust gas into the CO2 capture tower is 15-30m 3 / h and 4000~6000m 3 / h, the flow rate of the ship exhaust gas in the CO2 capture tower is 1~3m / s, and the residence time of the mixture of seawater and amine catalyst in the CO2 capture tower is 5~45min (that is, after passing into the CO2 capture tower, it stays for 5~45min and then is discharged); in step S2, the residence time of the mixed liquid I in the CO2 fixed reactor is 0~20min (that is, after passing into the CO2 fixed reactor, it stays for 0~20min and then is discharged); in step S3, the residence time of the mixed liquid II in the catalyst regenerator is 30~120min (that is, after passing into the catalyst regenerator, it stays for 30~120min and then is discharged).

[0044] Preferably, in step S3, the mixed solution III is concentrated to a content of the amine catalyst of not less than 85 wt %, and then recycled to step S1.

[0045] In a second aspect, the present invention provides a device for capturing and fixing carbon dioxide in ship exhaust gas using the method, comprising a mixing tank, a CO2 capture tower, a CO2 fixation reactor and a catalyst regenerator connected in sequence; the mixing tank is provided with a seawater inlet and a catalyst inlet; the CO2 capture tower is provided with a ship exhaust gas inlet and a decarbonized exhaust gas outlet; the CO2 fixation reactor and the catalyst regenerator are provided with a solid-liquid separator and a CO2 fixation product outlet; the catalyst regenerator is connected to the mixing tank.

[0046] Compared with the prior art, the present invention has the following advantages:

[0047] (1) By using the method and apparatus of the present invention, CO2 in ship exhaust gas can be captured and fixed directly using seawater, without consuming fresh water resources on the ship or undergoing a complicated desalination process on the seawater in advance.

[0048] (2) The method and apparatus of the present invention can fix the captured CO2 into a solid phase product without the need for additional CO2 compression, liquefaction equipment and CO2 storage tanks, thereby reducing the footprint of the device and lowering the energy consumption of the device.

[0049] (3) In the method and apparatus of the present invention, Ca in seawater is used 2+ and Mg 2+ Realizing the regeneration of amine catalysts can reduce the energy consumption of catalyst regeneration. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 This is a flow chart of capturing and fixing carbon dioxide in ship exhaust gas in Example 1.

[0051] Figure 2 This is a flow chart for capturing carbon dioxide from ship exhaust in Comparative Example 1.

[0052] Figure 3 This is a flow chart for capturing carbon dioxide from ship exhaust gas in Comparative Example 2. DETAILED DESCRIPTION

[0053] The present invention will be further described below with reference to the embodiments.

[0054] First, the present invention relates to a method for capturing and fixing carbon dioxide in ship exhaust gas, comprising the following steps:

[0055] S1: Pass seawater, amine catalyst and ship exhaust gas into the CO2 capture tower to complete the CO2 absorption reaction and discharge the decarbonized exhaust gas and mixed liquid I; the CO2 absorption reaction includes:

[0056] ,

[0057] ,

[0058] ,

[0059] Among them, CA is an amine catalyst;

[0060] S2: The mixed solution I is introduced into the CO2 fixation reactor. After the CO2 fixation precipitation reaction is completed, the solid and liquid are separated, and the CO2 fixation product and the mixed solution II are discharged. The CO2 fixation precipitation reaction includes:

[0061] ,

[0062] ;

[0063] S3: The mixed liquid II is passed into the catalyst regenerator. After the catalyst regeneration reaction is completed, the solid and liquid are separated, and the CO2 fixed product and the mixed liquid III are discharged. The mixed liquid III is concentrated and then reused in S1. The catalyst regeneration reaction includes:

[0064] ,

[0065] .

[0066] In some specific embodiments, in step S3, the mixed solution III is concentrated to a content of the amine catalyst of not less than 85 wt%, and then recycled to step S1.

[0067] In some specific embodiments, in step S1, the amine catalyst is the following a) or b):

[0068] a) comprising diethylenetriamine and 2,2,6,6-tetramethylpiperidine in a mass ratio of 1:0.0033-0.2;

[0069] b) comprising 2-amino-2-methyl-1-propanol and 1-methyl-4-piperidinol in a mass ratio of 1:0.15-1.6.

[0070] In some specific embodiments, in step S1, the specific process of passing seawater, amine catalyst and ship exhaust gas into the CO2 capture tower includes: mixing seawater and amine catalyst in a mass ratio of 1:0.05~4, passing the obtained mixture of seawater and amine catalyst into the CO2 capture tower, and simultaneously passing ship exhaust gas into the CO2 capture tower; the flow rate of the mixture of seawater and amine catalyst and the ship exhaust gas into the CO2 capture tower is 15~30m 3 / h and 4000~6000m 3 / h, the flow rate of ship exhaust gas in the CO2 capture tower is 1~3m / s, and the residence time of the mixture of seawater and amine catalyst in the CO2 capture tower is 5~45min.

[0071] In some specific embodiments, in step S1, the CO2 capture tower is a packed tower, a plate tower or a hollow fiber membrane contactor.

[0072] In some specific embodiments, in step S1, the operating temperature of the CO2 capture tower is 20-80°C.

[0073] In some specific embodiments, in step S2, the operating temperature of the CO2 fixation reactor is 20-50°C, and the residence time of the mixed solution I in the CO2 fixation reactor is 0-20 min.

[0074] In some specific embodiments, in step S3, the operating temperature of the catalyst regenerator is 20-50° C., and the residence time of the mixed solution II in the catalyst regenerator is 30-120 min.

[0075] Second, the present invention relates to a device for capturing and fixing carbon dioxide in ship exhaust gas using the method, comprising a mixing tank, a CO2 capture tower, a CO2 fixation reactor and a catalyst regenerator connected in sequence; the mixing tank is provided with a seawater inlet and a catalyst inlet; the CO2 capture tower is provided with a ship exhaust gas inlet and a decarbonized exhaust gas outlet; the CO2 fixation reactor and the catalyst regenerator are provided with a solid-liquid separator and a CO2 fixation product outlet; the catalyst regenerator is connected to the mixing tank.

[0076] The present invention is described below by way of specific examples. It should be understood that these examples are intended only to illustrate the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit and scope of the inventive concept, any changes and advantages that can be imagined 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.

[0077] Example 1

[0078] The device for capturing and fixing carbon dioxide in ship exhaust gas in this embodiment comprises a mixing tank, a CO2 capture tower, a CO2 fixation reactor and a catalyst regenerator connected in sequence, wherein the catalyst regenerator is connected to the mixing tank; the mixing tank is provided with a seawater inlet and a catalyst inlet, the CO2 capture tower is provided with a ship exhaust gas inlet and a decarbonized exhaust gas outlet, and the CO2 fixation reactor and the catalyst regenerator are provided with a solid-liquid separator and a CO2 fixation product outlet. The device is used to capture and fix carbon dioxide in ship exhaust gas, and the process is as follows: Figure 1 The specific steps are as follows:

[0079] S1: introducing seawater and an amine catalyst into a mixing tank and mixing them to obtain a seawater / amine catalyst mixture, wherein the content of the amine catalyst is 30 wt %. The amine catalyst is a two-component catalyst composed of diethylenetriamine and 2,2,6,6-tetramethylpiperidine in a mass ratio of 1:0.0033.

[0080] S2: The seawater / amine catalyst mixture and ship exhaust gas were respectively 3 / h and 5000m 3 The CO2 capture tower is fed with a flow rate of 1 / h. The operating temperature of the CO2 capture tower is 40°C, the flow rate of the ship's exhaust gas in the CO2 capture tower is 1 m / s, and the residence time of the seawater / amine catalyst mixture in the CO2 capture tower is 15 minutes. Within the CO2 capture tower, the CO2 absorption reaction is completed, and a partial CO2 fixation and precipitation reaction occurs simultaneously. The decarbonized exhaust gas and mixed liquid I are discharged from the CO2 capture tower.

[0081] S3: Mixed liquor I discharged from the CO2 capture tower is passed into the CO2 fixation reactor. The CO2 fixation reactor operates at 50°C and has a residence time of 5 minutes. Within the CO2 fixation reactor, CO2 fixation precipitation reactions are completed, while a partial catalyst regeneration reaction also occurs. Solid-liquid separation is performed at the outlet of the CO2 fixation reactor to separate the CO2 fixation products (CaCO3 and MgCO3), and the remaining mixed liquor II is discharged.

[0082] S4: Mixed liquid II is passed into a catalyst regenerator at an operating temperature of 50°C. Mixed liquid II resides in the regenerator for 60 minutes. Catalyst regeneration is completed within the regenerator. Solid-liquid separation is performed at the regenerator outlet to separate the CO2 fixed products (CaCO3 and MgCO3). Mixed liquid III is then discharged and concentrated to a 90wt% amine catalyst content. The mixture is then passed into a mixing tank for reuse, achieving the recycling of the amine catalyst.

[0083] Example 2

[0084] The device for capturing and fixing carbon dioxide in ship exhaust gas in this embodiment is the same as that in embodiment 1. The device is used to capture and fix carbon dioxide in ship exhaust gas. The process is as follows: Figure 1 The specific steps are as follows:

[0085] S1: introducing seawater and an amine catalyst into a mixing tank and mixing them to obtain a seawater / amine catalyst mixture, wherein the content of the amine catalyst is 30 wt %. The amine catalyst is a two-component catalyst composed of diethylenetriamine and 2,2,6,6-tetramethylpiperidine in a mass ratio of 1:0.2.

[0086] S2: The seawater / amine catalyst mixture and ship exhaust gas were respectively 3 / h and 5000m 3 The CO2 capture tower is fed with a flow rate of 1 / h. The operating temperature of the CO2 capture tower is 40°C, the flow rate of the ship's exhaust gas in the CO2 capture tower is 1 m / s, and the residence time of the seawater / amine catalyst mixture in the CO2 capture tower is 15 minutes. Within the CO2 capture tower, the CO2 absorption reaction is completed, and a partial CO2 fixation and precipitation reaction occurs simultaneously. The decarbonized exhaust gas and mixed liquid I are discharged from the CO2 capture tower.

[0087] S3: Mixed liquor I discharged from the CO2 capture tower is passed into the CO2 fixation reactor. The CO2 fixation reactor operates at 50°C and has a residence time of 5 minutes. Within the CO2 fixation reactor, CO2 fixation precipitation reactions are completed, while a partial catalyst regeneration reaction also occurs. Solid-liquid separation is performed at the outlet of the CO2 fixation reactor to separate the CO2 fixation products (CaCO3 and MgCO3), and the remaining mixed liquor II is discharged.

[0088] S4: Mixed liquid II is passed into a catalyst regenerator at an operating temperature of 50°C. Mixed liquid II resides in the regenerator for 60 minutes. Catalyst regeneration is completed within the regenerator. Solid-liquid separation is performed at the regenerator outlet to separate the CO2 fixed products (CaCO3 and MgCO3). Mixed liquid III is then discharged and concentrated to a 90wt% amine catalyst content. The mixture is then passed into a mixing tank for reuse, achieving the recycling of the amine catalyst.

[0089] Example 3

[0090] The device for capturing and fixing carbon dioxide in ship exhaust gas in this embodiment is the same as that in embodiment 1. The device is used to capture and fix carbon dioxide in ship exhaust gas. The process is as follows: Figure 1 The specific steps are as follows:

[0091] S1: introducing seawater and an amine catalyst into a mixing tank and mixing them to obtain a seawater / amine catalyst mixture, wherein the amine catalyst content is 30 wt %. The amine catalyst is a two-component catalyst composed of 2-amino-2-methyl-1-propanol and 1-methyl-4-piperidinol in a mass ratio of 1:0.15.

[0092] S2: The seawater / amine catalyst mixture and ship exhaust gas were respectively 3 / h and 5000m 3 The CO2 capture tower is fed with a flow rate of 1 / h. The operating temperature of the CO2 capture tower is 40°C, the flow rate of the ship's exhaust gas in the CO2 capture tower is 1 m / s, and the residence time of the seawater / amine catalyst mixture in the CO2 capture tower is 15 minutes. Within the CO2 capture tower, the CO2 absorption reaction is completed, and a partial CO2 fixation and precipitation reaction occurs simultaneously. The decarbonized exhaust gas and mixed liquid I are discharged from the CO2 capture tower.

[0093] S3: Mixed liquor I discharged from the CO2 capture tower is passed into the CO2 fixation reactor. The CO2 fixation reactor operates at 50°C and has a residence time of 5 minutes. Within the CO2 fixation reactor, CO2 fixation precipitation reactions are completed, while a partial catalyst regeneration reaction also occurs. Solid-liquid separation is performed at the outlet of the CO2 fixation reactor to separate the CO2 fixation products (CaCO3 and MgCO3), and the remaining mixed liquor II is discharged.

[0094] S4: Mixed liquid II is passed into a catalyst regenerator at an operating temperature of 50°C. Mixed liquid II resides in the regenerator for 60 minutes. Catalyst regeneration is completed within the regenerator. Solid-liquid separation is performed at the regenerator outlet to separate the CO2 fixed products (CaCO3 and MgCO3). Mixed liquid III is then discharged and concentrated to a 90wt% amine catalyst content. The mixture is then passed into a mixing tank for reuse, achieving the recycling of the amine catalyst.

[0095] Example 4

[0096] The device for capturing and fixing carbon dioxide in ship exhaust gas in this embodiment is the same as that in embodiment 1. The device is used to capture and fix carbon dioxide in ship exhaust gas. The process is as follows: Figure 1 The specific steps are as follows:

[0097] S1: introducing seawater and an amine catalyst into a mixing tank and mixing them to obtain a seawater / amine catalyst mixture, wherein the amine catalyst content is 30 wt %. The amine catalyst is a two-component catalyst composed of 2-amino-2-methyl-1-propanol and 1-methyl-4-piperidinol in a mass ratio of 1:1.6.

[0098] S2: The seawater / amine catalyst mixture and ship exhaust gas were respectively 3 / h and 5000m 3 The CO2 capture tower is fed with a flow rate of 1 / h. The operating temperature of the CO2 capture tower is 40°C, the flow rate of the ship's exhaust gas in the CO2 capture tower is 1 m / s, and the residence time of the seawater / amine catalyst mixture in the CO2 capture tower is 15 minutes. Within the CO2 capture tower, the CO2 absorption reaction is completed, and a partial CO2 fixation and precipitation reaction occurs simultaneously. The decarbonized exhaust gas and mixed liquid I are discharged from the CO2 capture tower.

[0099] S3: Mixed liquor I discharged from the CO2 capture tower is passed into the CO2 fixation reactor. The CO2 fixation reactor operates at 50°C and has a residence time of 5 minutes. Within the CO2 fixation reactor, CO2 fixation precipitation reactions are completed, while a partial catalyst regeneration reaction also occurs. Solid-liquid separation is performed at the outlet of the CO2 fixation reactor to separate the CO2 fixation products (CaCO3 and MgCO3), and the remaining mixed liquor II is discharged.

[0100] S4: Mixed liquid II is passed into a catalyst regenerator at an operating temperature of 50°C. Mixed liquid II resides in the regenerator for 60 minutes. Catalyst regeneration is completed within the regenerator. Solid-liquid separation is performed at the regenerator outlet to separate the CO2 fixed products (CaCO3 and MgCO3). Mixed liquid III is then discharged and concentrated to a 90wt% amine catalyst content. The mixture is then passed into a mixing tank for reuse, achieving the recycling of the amine catalyst.

[0101] Comparative Example 1

[0102] In this comparative example, the process of capturing carbon dioxide from ship exhaust is as follows: Figure 2 As shown, the absorbent used is a 30wt% monoethanolamine (MEA) solution (the solvent is deionized water), the residence time in the CO2 capture tower is 15min; the flow rate of the ship's exhaust gas into the CO2 capture tower is 5000m 3 / h, the flow rate in the CO2 capture tower is 1m / s; the operating temperature of the CO2 capture tower is 40℃, and the temperature of the CO2 desorption tower is 100℃.

[0103] Comparative Example 2

[0104] In this comparative example, the process of capturing carbon dioxide from ship exhaust is as follows: Figure 3 As shown, the total salt concentration of seawater is 3.5wt%, the total salt concentration of concentrated seawater is 7wt%; the concentration of sodium hydroxide solution obtained by bipolar membrane electrodialysis is 1mol / L, the residence time in the CO2 capture tower is 15min; the flow rate of ship exhaust gas into the CO2 capture tower is 5000m 3 / h, the flow rate in the CO2 capture tower is 1m / s; the operating temperature of the CO2 capture tower is 40℃.

[0105] Comparative Example 3

[0106] The device for capturing and fixing carbon dioxide in ship exhaust gas of this comparative example is the same as that in Example 1. The device is used to capture and fix carbon dioxide in ship exhaust gas. The process is as follows: Figure 1 The specific steps are as follows:

[0107] S1: introducing seawater and diethylenetriamine (as an amine catalyst) into a mixing tank and mixing them to obtain a seawater / diethylenetriamine mixture, wherein the diethylenetriamine content is 30 wt%.

[0108] S2: The seawater / diethylenetriamine mixture and ship exhaust gas were respectively 3 / h and 5000m 3The CO2 capture tower is fed with a flow rate of 1 / h. The operating temperature of the CO2 capture tower is 40°C, the flow rate of the ship's exhaust gas in the CO2 capture tower is 1 m / s, and the residence time of the seawater / diethylenetriamine mixture in the CO2 capture tower is 15 minutes. Within the CO2 capture tower, the CO2 absorption reaction is completed, and a partial CO2 fixation and precipitation reaction occurs simultaneously. The decarbonized exhaust gas and mixed liquid I are discharged from the CO2 capture tower.

[0109] S3: Mixed liquor I discharged from the CO2 capture tower is passed into the CO2 fixation reactor. The CO2 fixation reactor operates at 50°C and has a residence time of 5 minutes. Within the CO2 fixation reactor, CO2 fixation precipitation reactions are completed, while a partial catalyst regeneration reaction also occurs. Solid-liquid separation is performed at the outlet of the CO2 fixation reactor to separate the CO2 fixation products (CaCO3 and MgCO3), and the remaining mixed liquor II is discharged.

[0110] S4: Mixed liquid II is passed into a catalyst regenerator at an operating temperature of 50°C. Mixed liquid II resides in the regenerator for 60 minutes. Catalyst regeneration is completed within the regenerator. Solid-liquid separation is performed at the regenerator outlet to separate the CO2 fixed products (CaCO3 and MgCO3). Mixed liquid III is then discharged and concentrated to a 90wt% amine catalyst content. The mixture is then passed into a mixing tank for reuse, achieving the recycling of the amine catalyst.

[0111] Comparative Example 4

[0112] The device for capturing and fixing carbon dioxide in ship exhaust gas of this comparative example is the same as that in Example 1. The device is used to capture and fix carbon dioxide in ship exhaust gas. The process is as follows: Figure 1 The specific steps are as follows:

[0113] S1: introducing seawater and 2,2,6,6-tetramethylpiperidine (as an amine catalyst) into a mixing tank and mixing them to obtain a seawater / 2,2,6,6-tetramethylpiperidine mixture, wherein the content of 2,2,6,6-tetramethylpiperidine is 30 wt%.

[0114] S2: The seawater / 2,2,6,6-tetramethylpiperidine mixture and ship exhaust gas were respectively 3 / h and 5000m 3The CO2 capture tower is fed with a flow rate of 1 / h. The operating temperature of the CO2 capture tower is 40°C, the flow rate of the ship's exhaust gas in the CO2 capture tower is 1 m / s, and the residence time of the seawater / 2,2,6,6-tetramethylpiperidine mixture in the CO2 capture tower is 15 minutes. Within the CO2 capture tower, the CO2 absorption reaction is completed, and a partial CO2 fixation and precipitation reaction occurs simultaneously. The decarbonized exhaust gas and mixed liquid I are discharged from the CO2 capture tower.

[0115] S3: Mixed liquor I discharged from the CO2 capture tower is passed into the CO2 fixation reactor. The CO2 fixation reactor operates at 50°C and has a residence time of 5 minutes. Within the CO2 fixation reactor, CO2 fixation precipitation reactions are completed, while a partial catalyst regeneration reaction also occurs. Solid-liquid separation is performed at the outlet of the CO2 fixation reactor to separate the CO2 fixation products (CaCO3 and MgCO3), and the remaining mixed liquor II is discharged.

[0116] S4: Mixed liquid II is passed into a catalyst regenerator at an operating temperature of 50°C. Mixed liquid II resides in the regenerator for 60 minutes. Catalyst regeneration is completed within the regenerator. Solid-liquid separation is performed at the regenerator outlet to separate the CO2 fixed products (CaCO3 and MgCO3). Mixed liquid III is then discharged and concentrated to a 90wt% amine catalyst content. The mixture is then passed into a mixing tank for reuse, achieving the recycling of the amine catalyst.

[0117] Comparative Example 5

[0118] The device for capturing and fixing carbon dioxide in ship exhaust gas of this comparative example is the same as that in Example 1. The device is used to capture and fix carbon dioxide in ship exhaust gas. The process is as follows: Figure 1 The specific steps are as follows:

[0119] S1: Seawater and 2-amino-2-methyl-1-propanol (as an amine catalyst) are introduced into a mixing tank and mixed to obtain a seawater / 2-amino-2-methyl-1-propanol mixture, wherein the content of 2-amino-2-methyl-1-propanol is 30 wt%.

[0120] S2: The seawater / 2-amino-2-methyl-1-propanol mixture and ship exhaust gas were respectively 3 / h and 5000m 3The CO2 capture tower is fed with a flow rate of 1 / h. The operating temperature of the CO2 capture tower is 40°C, the flow rate of the ship's exhaust gas in the CO2 capture tower is 1 m / s, and the residence time of the seawater / 2-amino-2-methyl-1-propanol mixture in the CO2 capture tower is 15 minutes. Within the CO2 capture tower, the CO2 absorption reaction is completed, and a partial CO2 fixation and precipitation reaction occurs simultaneously. The decarbonized exhaust gas and mixed liquid I are discharged from the CO2 capture tower.

[0121] S3: Mixed liquor I discharged from the CO2 capture tower is passed into the CO2 fixation reactor. The CO2 fixation reactor operates at 50°C and has a residence time of 5 minutes. Within the CO2 fixation reactor, CO2 fixation precipitation reactions are completed, while a partial catalyst regeneration reaction also occurs. Solid-liquid separation is performed at the outlet of the CO2 fixation reactor to separate the CO2 fixation products (CaCO3 and MgCO3), and the remaining mixed liquor II is discharged.

[0122] S4: Mixed liquid II is passed into a catalyst regenerator at an operating temperature of 50°C. Mixed liquid II resides in the regenerator for 60 minutes. Catalyst regeneration is completed within the regenerator. Solid-liquid separation is performed at the regenerator outlet to separate the CO2 fixed products (CaCO3 and MgCO3). Mixed liquid III is then discharged and concentrated to a 90wt% amine catalyst content. The mixture is then passed into a mixing tank for reuse, achieving the recycling of the amine catalyst.

[0123] Comparative Example 6

[0124] The device for capturing and fixing carbon dioxide in ship exhaust gas of this comparative example is the same as that in Example 1. The device is used to capture and fix carbon dioxide in ship exhaust gas. The process is as follows: Figure 1 The specific steps are as follows:

[0125] S1: introducing seawater and 1-methyl-4-piperidinol (as an amine catalyst) into a mixing tank and mixing to obtain a seawater / 1-methyl-4-piperidinol mixture, wherein the content of 1-methyl-4-piperidinol is 30 wt%.

[0126] S2: The seawater / 1-methyl-4-piperidinol mixture and ship exhaust gas were respectively 3 / h and 5000m 3The CO2 capture tower is fed with a flow rate of 1 / h. The operating temperature of the CO2 capture tower is 40°C, the flow rate of the ship's exhaust gas in the CO2 capture tower is 1 m / s, and the residence time of the seawater / 1-methyl-4-piperidinol mixture in the CO2 capture tower is 15 minutes. Within the CO2 capture tower, the CO2 absorption reaction is completed, and a partial CO2 fixation and precipitation reaction occurs simultaneously. The decarbonized exhaust gas and mixed liquid I are discharged from the CO2 capture tower.

[0127] S3: Mixed liquor I discharged from the CO2 capture tower is passed into the CO2 fixation reactor. The CO2 fixation reactor operates at 50°C and has a residence time of 5 minutes. Within the CO2 fixation reactor, CO2 fixation precipitation reactions are completed, while a partial catalyst regeneration reaction also occurs. Solid-liquid separation is performed at the outlet of the CO2 fixation reactor to separate the CO2 fixation products (CaCO3 and MgCO3), and the remaining mixed liquor II is discharged.

[0128] S4: Mixed liquid II is passed into a catalyst regenerator at an operating temperature of 50°C. Mixed liquid II resides in the regenerator for 60 minutes. Catalyst regeneration is completed within the regenerator. Solid-liquid separation is performed at the regenerator outlet to separate the CO2 fixed products (CaCO3 and MgCO3). Mixed liquid III is then discharged and concentrated to a 90wt% amine catalyst content. The mixture is then passed into a mixing tank for reuse, achieving the recycling of the amine catalyst.

[0129] Test Example 1: Performance comparison of different devices and methods

[0130] In Example 1, Comparative Example 1 and Comparative Example 2, the ship exhaust gas used in the tests was the same, and the CO2 concentration was 4.5 mol%. The energy consumption, CO2 capture capacity and absorbent or catalyst loss of each device and method are shown in Table 1, where:

[0131] (1) “CO2 capture rate” is the percentage of CO2 captured by the CO2 capture tower to the CO2 content in the inlet ship exhaust gas. The calculation formula is as follows: CO2 capture rate = (flue gas inlet flow rate × inlet CO2 concentration - flue gas flow rate after decarbonization × outlet CO2 concentration) / (flue gas inlet flow rate × inlet CO2 concentration).

[0132] (2) The energy consumption of absorbent regeneration in Example 1 is "0 to 0.5 GJ / ton CO2 (heating steam)", which means: insulation measures can be adopted to rely on the heat released by the CO2 absorption reaction to provide heat for the catalyst regeneration reaction. In this case, the energy consumption of absorbent regeneration is 0 and no additional heat is required; or no protective measures can be adopted and heating steam can be used to provide heat for the catalyst regenerator. In this case, the energy consumption of absorbent regeneration is 0.5 GJ / ton CO2 (heating steam).

[0133] (3) The absorbent loss in Comparative Example 2 is 1 kg / ton CO2. This is because: the theoretical reaction is that sodium hydroxide (absorbent) reacts with CO2 to produce sodium carbonate, but the actual product is a mixture of sodium hydroxide and sodium carbonate, that is, the product contains absorbent, thus causing "absorbent loss".

[0134] Table 1 Performance comparison of different devices and methods

[0135]

[0136] According to Table 1, we can see that:

[0137] Compared to Comparative Examples 1 and 2, Example 1 employs the apparatus and method of the present invention, effectively reducing the overall operating energy consumption of the apparatus. Furthermore, only an additional solid product storage tank is required, which occupies less floor space than CO2 compression, liquefaction, and liquid product storage tanks. Furthermore, both Comparative Example 1 and the apparatus and method of the present invention achieve cyclic regeneration of the absorbent or catalyst, with the catalyst loss of the present invention being significantly lower than the absorbent loss in Comparative Example 1.

[0138] Test Example 2: Performance comparison of different amine catalysts

[0139] In Examples 1 to 4 and Comparative Examples 3 to 6, the ship exhaust gas used in the tests was the same, and the CO2 concentration was 4.5 mol%. The CO2 capture capacity and amine catalyst loss of each device and method are shown in Table 2, where the meaning and calculation formula of "CO2 capture rate" are the same as those in Table 1.

[0140] Table 2 Performance comparison of different amine catalysts

[0141]

[0142] According to Table 2, we can see that:

[0143] (1) Compared with Example 1 and Example 2, the amine catalyst loss in Comparative Examples 3 and 4 is higher, and the CO2 capture rate in Comparative Example 4 is lower. This shows that diethylenetriamine and 2,2,6,6-tetramethylpiperidine can produce a synergistic effect, which can improve the stability of the amine catalyst while ensuring the CO2 capture capacity and reduce its loss during long-term operation. The reason for this is that among the two components mentioned above, diethylenetriamine can give the amine catalyst a better CO2 capture capacity, but it has a higher degradation loss when used alone. The conjugation effect and steric effect between diethylenetriamine and 2,2,6,6-tetramethylpiperidine can improve the stability of both.

[0144] (2) Compared with Example 3 and Example 4, the CO2 capture rate of Comparative Examples 5 and 6 is lower, and the loss of amine catalyst is higher. This shows that 2-amino-2-methyl-1-propanol and 1-methyl-4-piperidinol can produce a synergistic effect, which can improve the stability of the amine catalyst while ensuring the CO2 capture capacity and reduce its loss during long-term operation. The reason for this is that 2-amino-2-methyl-1-propanol has a good CO2 capture capacity, but its volatilization loss is high when used alone. When 2-amino-2-methyl-1-propanol and 1-methyl-4-piperidinol are used in combination, the intermolecular hydrogen bond formed between the two can be utilized to reduce the volatilization loss of 2-amino-2-methyl-1-propanol. At the same time, 1-methyl-4-piperidinol can provide hydrogen protons for the reaction between 2-amino-2-methyl-1-propanol and CO2, thereby improving the CO2 capture efficiency.

[0145] Unless otherwise defined, all technical and scientific terms used herein have the same meanings as commonly understood by those skilled in the art to which this disclosure pertains. Unless otherwise specified, the raw materials and equipment used herein are conventional in the art and can be obtained from conventional commercial sources. The methods used herein are conventional in the art, unless otherwise specified.

[0146] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent transformation made to the above embodiment based on the technical essence of the present invention still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A method for capturing and fixing carbon dioxide in ship exhaust, characterized in that: The following steps are involved: S1: Pass seawater, amine catalyst and ship exhaust gas into the CO2 capture tower to complete the CO2 absorption reaction. At the same time, a partial CO2 fixation and precipitation reaction occurs in the CO2 capture tower, and decarbonized exhaust gas and mixed liquid I are discharged. The CO2 absorption reaction includes: ， ， ， Wherein, CA is an amine catalyst; the amine catalyst is the following a) or b): a) a mixture comprising diethylenetriamine and 2,2,6,6-tetramethylpiperidine in a mass ratio of 1:(0.0033-0.2); b) comprising 2-amino-2-methyl-1-propanol and 1-methyl-4-piperidinol in a mass ratio of 1:(0.15-1.6); S2: The mixed solution I is introduced into the CO2 fixation reactor. After the CO2 fixation precipitation reaction is completed and a partial catalyst regeneration reaction occurs, the solid-liquid separation is performed and the CO2 fixation product and the mixed solution II are discharged. The CO2 fixation precipitation reaction includes: ， ； S3: The mixed liquid II is passed into the catalyst regenerator. After the catalyst regeneration reaction is completed, the solid and liquid are separated, and the CO2 fixed product and the mixed liquid III are discharged. The mixed liquid III is concentrated and then reused in S1. The catalyst regeneration reaction includes: ， 。 2. The method according to claim 1, characterized in that In step S1, the CO2 capture tower is a packed tower, a plate tower or a hollow fiber membrane contactor.

3. The method according to claim 1, characterized in that In step S1, the operating temperature of the CO2 capture tower is 20~80℃.

4. The method according to claim 1, wherein In step S2, the operating temperature of the CO2 fixation reactor is 20~50℃.

5. The method according to claim 1, wherein In step S3, the operating temperature of the catalyst regenerator is 20-50°C.

6. The method according to claim 1 or 2, characterized in that In step S1, the specific process of passing seawater, amine catalyst and ship exhaust gas into the CO2 capture tower includes: mixing seawater and amine catalyst in a mass ratio of 1:0.05~4, passing the obtained mixture of seawater and amine catalyst into the CO2 capture tower, and simultaneously passing ship exhaust gas into the CO2 capture tower.

7. The method according to claim 6, characterized in that In step S1, the flow rate of the mixture of seawater and amine catalyst and the ship exhaust gas into the CO2 capture tower is 15~30m 3 / h and 4000~6000m 3 / h, the flow rate of ship exhaust gas in the CO2 capture tower is 1~3m / s, and the residence time of the mixture of seawater and amine catalyst in the CO2 capture tower is 5~45min.

8. The method according to claim 6, characterized in that In step S2, the residence time of the mixed solution I in the CO2 fixation reactor is 5 to 20 minutes.

9. The method according to claim 6, characterized in that In step S3, the residence time of the mixed solution II in the catalyst regenerator is 30 to 120 minutes.

10. The method according to claim 1, characterized in that In step S3, the mixed solution III is concentrated to a content of the amine catalyst of not less than 85 wt %, and then recycled to step S1.

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