A CO2 absorbent, enhanced amine flue gas decarbonization method and decarbonization device

Abstract

The present invention provides a CO2 absorbent, an enhanced amine-based flue gas decarbonization method, and a decarbonization device, wherein the absorbent is primarily composed of a shuttling agent and a proton receptor; preferably, the molar ratio of the shuttling agent to the proton receptor is 1:1-1:5; preferably, the molar ratio of the shuttling agent to the proton receptor is 1:3. The present invention configures the absorbent and introduces flue gas broken into microbubbles into the absorbent. The microbubbles, influenced by drag, can advance synchronously with the liquid phase, forming a uniform gas-liquid mixture. This increases the absorbent's circulating load, thereby reducing the total energy consumption of the decarbonization process and improving the CO2 removal efficiency.

Description

Technical Field

[0001] The present invention belongs to the technical field of flue gas purification, and in particular to a CO2 absorbent, an enhanced amine-based flue gas decarbonization method, and a decarbonization device. Background Art

[0002] In the field of carbon capture, utilization, and storage (CCUS), amine / ammonia-based decarbonization technologies are widely used, playing a particularly important role in capturing and utilizing large-scale flue gas carbon sources. However, in practice, most decarbonization methods have a slow carbon dioxide capture rate, poor CO2 capture efficiency, and high regeneration energy consumption. Therefore, effectively reducing regeneration energy consumption and achieving high CO2 capture efficiency and rate are key to achieving widespread application of this technology.

[0003] In view of this, the present invention is proposed. Summary of the Invention

[0004] The first object of the present invention is to provide a CO2 absorbent that combines a shuttle agent with a proton receiver, thereby accelerating the CO2 capture rate by using the shuttle agent, and by combining with the proton receiver, thereby increasing the shuttle agent capture rate while also having a higher CO2 absorption capacity.

[0005] The second object of the present invention is to provide an enhanced amine-based flue gas decarbonization method, which configures an absorbent and introduces flue gas that is broken into microbubbles into the absorbent. The microbubbles are affected by the drag force and can move forward synchronously with the liquid phase to form a uniform gas-liquid mixture. In this way, the circulation load of the absorbent is increased, thereby reducing the total energy consumption of the decarbonization process and improving the CO2 removal effect.

[0006] The third object of the present invention is to provide a decarbonization device corresponding to the enhanced amine flue gas decarbonization method, which has low construction cost and simple operation.

[0007] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are adopted:

[0008] A CO2 absorbent, the absorbent mainly consisting of a shuttle agent and a proton receiving agent;

[0009] Preferably, the molar ratio of the shuttle agent to the proton acceptor is 1:1-1:5;

[0010] Preferably, the molar ratio of the shuttling agent to the proton acceptor is 1:3.

[0011] In the present invention, the configuration of the absorbent is very important for the present invention. This is because in the process of preliminary decarbonization of flue gas, the shuttle agent itself acts as a rate accelerator and also has a certain carbon dioxide capture effect. It can also enhance the activity of the proton receiver, which can accelerate the capture rate of CO2 and further improve the reaction rate during the preliminary decarbonization of flue gas. Then, after the flue gas is introduced into the rich liquid obtained after the preliminary decarbonization, the flue gas is broken into microbubbles. The microbubbles are affected by the drag force and can move forward synchronously with the rich liquid, thereby forming a uniform gas-liquid mixture. At this time, the presence of the shuttle agent can further enhance the activity of the proton receiver. This is because the reduction in bubble size will produce a free radical effect, causing the chemical bonds in the solution to break to form hydroxyl radicals and hydrogen radicals. Hydrogen radicals promote the chemical dissolution of CO2 and form protons. Due to the presence of the proton acceptor, the protons and hydroxyl radicals formed after these fragmentations interact with the proton acceptor, preventing them from binding to the shuttle agent and occupying sites on the shuttle agent that belong to carbon dioxide, reducing its carbon dioxide capture efficiency. During the initial decarburization of flue gas, the presence of the shuttle agent can cause carbonic acid to be present in the rich liquid obtained after the initial decarburization. Due to the instability of carbonic acid itself, it will decompose to produce hydrogen ions and bicarbonate ions. These hydrogen ions can also bind to the proton acceptor, thereby enhancing the activity of the proton acceptor. Moreover, due to the presence of the proton acceptor, during the initial decarburization of flue gas, hydrogen ions will not bind to the shuttle agent and occupy carbon dioxide sites, thereby reducing its carbon dioxide capture efficiency. Therefore, in the present invention, by combining the shuttle agent and the proton acceptor, the activity of the proton acceptor is enhanced by the shuttle agent, while the presence of the proton acceptor also ensures that the carbon dioxide capture efficiency of the shuttle agent is not affected. In summary, for the present invention, the molar ratio of the shuttle agent to the proton acceptor is very important. In the decarbonization method of the present invention, if there is too much shuttle agent, the amount of proton acceptor will be correspondingly reduced, so that the sites on the shuttle agent belonging to carbon dioxide are occupied by a portion of hydrogen ions, which affects the shuttle agent's carbon dioxide capture effect and also affects the reaction rate. If there is too little shuttle agent, there will be too much proton acceptor, and the activity of a portion of the proton acceptor cannot be enhanced. In addition, too little shuttle agent will reduce the reaction rate of the initial decarbonization, and its capture of carbon dioxide in the flue gas will also be correspondingly reduced.

[0012] Preferably, as a further feasible solution, the shuttling agent is one or more of 2-amino-2-methyl-1-propanol, monoethanolamine, piperazine, N-methylpiperazine, benzylamine and piperidine.

[0013] Preferably, as a further feasible solution, the shuttling agent is a mixture of N-methylpiperazine and monoethanolamine.

[0014] In the present invention, by selecting one or more of 2-amino-2-methyl-1-propanol, monoethanolamine, piperazine, N-methylpiperazine, benzylamine and piperidine as a shuttling agent, and preferably selecting a mixture of N-methylpiperazine and monoethanolamine as the shuttling agent, the absorbent thus configured has a more excellent carbon dioxide capture effect, and by mixing the two, the reaction rate of the initial decarbonization reaction can be further improved. Among them, monoethanolamine is used as a shuttling agent to capture carbon dioxide. It has the characteristics of high capture efficiency, large solubility, and the ability to efficiently capture carbon dioxide, and can allow carbon dioxide to be adsorbed on its surface to form a solution. However, for the process of monoethanolamine absorbing carbon dioxide, it is generally necessary to select a high concentration of monoethanolamine to ensure the absorption rate and reaction stability, so that the solution formed by monoethanolamine and carbon dioxide is not easy to be absorbed. Desorption occurs in subsequent operations. However, since high-concentration monoethanolamine has certain toxicity and the process technology for absorbing carbon dioxide with high-concentration monoethanolamine is relatively high, it is necessary to control multiple conditions and parameters to achieve a better capture effect of carbon dioxide. The operation is difficult and not easy to control. The presence of N-methylpiperazine can reduce the usage concentration of monoethanolamine and improve the stability of the solution formed after monoethanolamine combines with carbon dioxide, so that the solution formed after monoethanolamine combines with carbon dioxide is not easy to desorb in the subsequent operation process, thereby affecting the capture effect of the absorbent on carbon dioxide; and N-methylpiperazine itself also has a certain capture effect on carbon dioxide. Therefore, the combination of the two can further enhance the removal of carbon dioxide by absorption and maintain stability, and is not easy to desorb in the subsequent operation process.

[0015] Preferably, as a further feasible solution, the molar ratio of N-methylpiperazine to monoethanolamine in the shuttle agent is (2:1)-(1:3).

[0016] Preferably, as a further feasible solution, the molar ratio of N-methylpiperazine to monoethanolamine in the shuttle agent is 1:1.

[0017] In the present invention, the molar ratio of N-methylpiperazine to monoethanolamine in the shuttling agent is crucial. This is because when the molar ratio of N-methylpiperazine to monoethanolamine is between (2:1) and (1:3), preferably 1:1, the absorbent produced by mixing the two exhibits excellent carbon dioxide capture efficiency. This mixture also maximizes the rate of the decarbonization reaction. Furthermore, the rich solution formed after carbon dioxide capture is more stable and less susceptible to desorption during subsequent operations. Therefore, excessive amounts of N-methylpiperazine in the absorbent compromise the carbon dioxide capture efficiency of the resulting absorbent. Excessive amounts of monoethanolamine render the resulting solution unstable, making it susceptible to desorption during subsequent operations, leading to premature carbon dioxide release.

[0018] Preferably, as a further feasible solution, the proton acceptor is one or more of diethanolamine, diisopropanolamine, triethanolamine and methyldiethanolamine.

[0019] Preferably, as a further feasible solution, the proton acceptor is methyldiethanolamine.

[0020] In order to achieve the above-mentioned object of the present invention, the present invention also provides a flue gas decarbonization method matched with the above-mentioned absorbent:

[0021] A method for enhanced amine-based flue gas decarbonization, comprising the following steps:

[0022] Prepare absorbent and preheat the absorbent;

[0023] Flue gas is introduced into the preheated absorbent to carry out decarbonization reaction to obtain rich liquid;

[0024] The flue gas that has been broken into microbubbles is introduced into the rich liquid again to obtain a gas-liquid mixture;

[0025] The supersaturated rich liquid is subjected to gas-liquid separation and regeneration to obtain high-purity CO2.

[0026] In the scheme of the present invention, firstly, an absorbent is configured, and then flue gas is passed into the absorbent to carry out a preliminary decarbonization reaction. In this preliminary decarbonization process, the absorbent can enrich the CO2 present in the flue gas. In this preliminary decarbonization process, there is a certain limit to the enrichment of CO2 by the absorbent. Therefore, the present invention has discovered through a series of creative work that after preliminary decarbonization of CO2 using the absorbent provided by the present invention, the load of the absorbed rich liquid generated at this time is the load of the traditional production process. The present invention passes flue gas broken into microbubbles into the rich liquid. The microbubbles are affected by the drag force and can move forward synchronously with the liquid phase, thereby forming a uniform gas-liquid mixture. In this way, the circulating load of the absorbent is increased, thereby reducing the total energy consumption of the decarbonization process and improving the CO2 removal effect. The diameter of the microbubbles is in the range of 100-300 μm. In this way, the activity of the absorbent can be further improved, the circulating load of the reaction solution can be increased, and its enrichment effect on CO2 can be improved, so that it has more excellent decarbonization performance and can further reduce the regeneration energy consumption. The load of the supersaturated rich liquid obtained is at least 1.2 times the load of the rich liquid obtained after the initial decarbonization. This is because the rich liquid obtained by the present invention after the initial decarbonization of the flue gas is mixed with the saturated absorbent and the flue gas that is broken into microbubbles in a new round to form a uniform gas-liquid mixture. The microbubbles are used to generate free radical effects and interfacial electric field effects in the formed microbubbles. Reducing the size of the bubbles can break the hydrogen bonds and hydroxyl bonds in the solution, thereby forming hydrogen radicals and hydroxyl radicals. The hydrogen radicals can promote the dissolution of CO2, and the hydroxyl radicals will interact with the absorbent. The combination of the two can improve the activity of the proton receiver, so that the proton receiver can further accept more dissolved carbon dioxide, and ultimately achieve an increase in the load.

[0027] Preferably, as a further feasible solution, the diameter of the microbubbles is micron-sized bubbles of 100-300 μm;

[0028] Preferably, the diameter of the microbubbles is 300 μm.

[0029] In the present invention, the size of the microbubbles is very important. This is because only when the size of the microbubbles is within an appropriate range can the gas-liquid mixture formed by the flue gas and the rich liquid produce a free radical effect and an interfacial electric field effect by reducing the bubble size, thereby enabling the absorbent to reach a higher load. The free radical effect can increase the activity of the absorbent and thus reduce the total energy consumption of the process. Therefore, for the present invention, when the diameter of the microbubbles is 100-300 μm, the free radical effect generated by the microbubbles is excellent for increasing the activity of the absorbent, thereby achieving a better absorption effect of carbon dioxide through the absorbent. If the diameter of the microbubbles is too large, the bubbles will be too large to produce the free radical effect and the interfacial electric field effect, so that the activity of the absorbent cannot be increased, thereby affecting the decarbonization effect of the flue gas; if the microbubbles are too small, the flue gas and the rich liquid will not be able to form a stable gas-liquid mixture after mixing.

[0030] In order to achieve the above-mentioned object of the present invention, the present invention also provides a flue gas decarbonization system used in the above-mentioned flue gas decarbonization method:

[0031] The process comprises a gas washing tower, a micro-interface reaction tower, a gas-liquid separation tank and a regeneration tower which are connected in sequence.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] (1) The present invention provides an absorbent that combines a shuttle agent with a proton receiver, thereby accelerating the CO2 capture rate by using the shuttle agent, and combining with the proton receiver to increase the shuttle agent capture rate while also having a higher CO2 absorption capacity.

[0034] (2) The present invention provides an enhanced amine-based flue gas decarbonization method, which comprises preparing an absorbent and then introducing flue gas that has been broken into microbubbles into the absorbent to form a uniform gas-liquid mixture, thereby enhancing the activity of the absorbent and increasing the circulating load of the absorbent, thereby reducing the total energy consumption of the decarbonization process and improving the CO2 removal effect.

[0035] (3) The present invention provides a decarbonization device corresponding to the enhanced amine flue gas decarbonization method, which has low construction cost and simple operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiment below. The accompanying drawings are for illustration purposes only and are not to be considered as limiting the present invention. The same reference symbols are used throughout the drawings to represent the same components. In the drawings:

[0037] Figure 1This is a graph drawn based on the measurement results of Experimental Example 3 of the present invention;

[0038] Figure 2 This is a graph drawn based on the measurement results of Experimental Example 4 of the present invention. DETAILED DESCRIPTION

[0039] The technical scheme of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and specific embodiments, but it will be understood by those skilled in the art that the following described embodiments are part of embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention, and should not be considered as limiting the scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of protection of the present invention. Those who do not specify specific conditions in the embodiments are carried out according to normal conditions or the conditions recommended by the manufacturer. Those whose reagents or instruments are not specified by the manufacturer are conventional products that can be purchased commercially.

[0040] In the description of the present invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate and simplify the description of the present invention. They are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation, and therefore should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0041] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0042] In order to more clearly illustrate the technical solutions of the present invention, specific embodiments are provided below for illustration.

[0043] Example 1

[0044] The implementation steps of the decarbonization method are as follows:

[0045] 2-Amino-2-methyl-1-propanol and diethanolamine are prepared as an absorbent in a molar ratio of 1:1, and then the prepared absorbent is preheated to 40°C and introduced into a gas scrubber for a preliminary decarbonization reaction;

[0046] The flue gas after the initial decarbonization will be discharged from the upper part of the scrubber, and the absorbent will undergo the initial decarbonization reaction in the scrubber to obtain rich liquid;

[0047] A new round of flue gas is introduced into the rich liquid and then into the micro-interface generator. Micro bubbles with a diameter of 100 μm are produced by adjusting the micro-interface generator tower to form a stable gas-liquid mixture.

[0048] The gas-liquid mixture naturally overflows into the micro-interface reaction tower for further flue gas decarbonization reaction to generate supersaturated rich liquid;

[0049] The supersaturated rich liquid is introduced into the gas-liquid separation tank and the regeneration tower in sequence to separate and regenerate the flue gas and the reaction liquid to obtain high-purity CO2 gas.

[0050] Example 2

[0051] The implementation steps of the decarbonization method are as follows:

[0052] 2-Amino-2-methyl-1-propanol and diethanolamine are prepared as an absorbent in a molar ratio of 1:5, and the prepared absorbent is then preheated to 40°C and introduced into a gas scrubber for a preliminary decarbonization reaction;

[0053] The flue gas after the initial decarbonization will be discharged from the upper part of the scrubber, and the absorbent will undergo the initial decarbonization reaction in the scrubber to obtain rich liquid;

[0054] A new round of flue gas is introduced into the rich liquid and then into the micro-interface generator. Microbubbles with a diameter of 600 μm are produced by adjusting the micro-interface generator tower to form a stable gas-liquid mixture.

[0055] The gas-liquid mixture naturally overflows into the micro-interface reaction tower for further flue gas decarbonization reaction to generate supersaturated rich liquid;

[0056] The supersaturated rich liquid is introduced into the gas-liquid separation tank and the regeneration tower in sequence to separate and regenerate the flue gas and the reaction liquid to obtain high-purity CO2 gas.

[0057] Example 3

[0058] The implementation steps of the decarbonization method are as follows:

[0059] 2-Amino-2-methyl-1-propanol and diethanolamine are prepared as an absorbent in a molar ratio of 1:3, and the prepared absorbent is then preheated to 40°C and introduced into a gas scrubber for a preliminary decarbonization reaction;

[0060] The flue gas after the initial decarbonization will be discharged from the upper part of the scrubber, and the absorbent will undergo the initial decarbonization reaction in the scrubber to obtain rich liquid;

[0061] A new round of flue gas is introduced into the rich liquid and then into the micro-interface generator. Microbubbles with a diameter of 500 μm are produced by adjusting the micro-interface generator tower to form a stable gas-liquid mixture.

[0062] The gas-liquid mixture naturally overflows into the micro-interface reaction tower for further flue gas decarbonization reaction to generate supersaturated rich liquid;

[0063] The supersaturated rich liquid is introduced into the gas-liquid separation tank and the regeneration tower in sequence to separate and regenerate the flue gas and the reaction liquid to obtain high-purity CO2 gas.

[0064] Example 4

[0065] The specific implementation steps are the same as those in Example 3, except that the shuttling agent 2-amino-2-methyl-1-propanol is replaced by monoethanolamine, and the molar ratio of monoethanolamine to the proton acceptor diethanolamine remains unchanged.

[0066] Example 5

[0067] The specific implementation steps are the same as those in Example 3, except that the shuttle agent 2-amino-2-methyl-1-propanol is replaced by N-methylpiperazine.

[0068] Example 6

[0069] The specific implementation steps are the same as those in Example 3, except that the shuttling agent is replaced by N-methylpiperazine and monoethanolamine mixed in a molar ratio of 2:1.

[0070] Example 7

[0071] The specific implementation steps are the same as those in Example 6, except that the shuttling agent is replaced by N-methylpiperazine and monoethanolamine mixed in a molar ratio of 2:3.

[0072] Example 8

[0073] The specific implementation steps are the same as those in Example 6, except that the shuttling agent is replaced by N-methylpiperazine and monoethanolamine mixed in a molar ratio of 1:1.

[0074] Example 9

[0075] The specific implementation steps are the same as those in Example 8, except that the proton acceptor diethanolamine is replaced by diisopropanolamine.

[0076] Example 10

[0077] The specific implementation steps are the same as those in Example 8, except that the proton acceptor diethanolamine is replaced by triethanolamine.

[0078] Example 11

[0079] The specific implementation steps are the same as those in Example 8, except that the proton acceptor diethanolamine is replaced by methyldiethanolamine.

[0080] Comparative Example 1

[0081] The specific implementation steps are the same as those in Example 11, except that N-methylpiperazine and monoethanolamine in the shuttling agent are mixed at a molar ratio of 0.5:1.

[0082] Comparative Example 2

[0083] The specific implementation steps are the same as those in Example 11, except that N-methylpiperazine and monoethanolamine in the shuttling agent are mixed at a molar ratio of 1:6.

[0084] Comparative Example 3

[0085] The specific implementation steps are the same as those in Example 11, except that the molar ratio of the mixture of the shuttling agent N-methylpiperazine and monoethanolamine to the proton acceptor methyldiethanolamine is adjusted to 0.5:1.

[0086] Comparative Example 4

[0087] The specific implementation steps are the same as those in Example 11, except that the molar ratio of the mixture of the shuttling agent N-methylpiperazine and monoethanolamine to the proton acceptor methyldiethanolamine is adjusted to 3:1.

[0088] Comparative Example 5

[0089] The specific implementation steps are the same as those in Example 11, except that the diameter of the microbubbles is adjusted to 50 μm.

[0090] Comparative Example 6

[0091] The specific implementation steps are the same as those in Example 11, except that the diameter of the microbubbles is adjusted to 800 μm.

[0092] Comparative Example 7

[0093] The specific implementation steps are the same as those in Example 11, except that a new round of flue gas is introduced into the rich liquid without breaking it into microbubbles, but is directly introduced into the microinterface reaction tower for decarbonization reaction.

[0094] Experimental Example 1 CO2 absorption rate measurement

[0095] The preset feed gas was treated according to the implementation scheme of Examples 1-11 and Comparative Examples 1-7, and the CO2 absorption rate was finally measured by gas chromatography, wherein the micro-interface generator used was a gas-liquid follower micro-interface generator, and the specific measurement method was as follows;

[0096] Chromatographic conditions: the detector was a thermal conductivity detector (TCD); the chromatographic column was an activated carbon column; the detection current was 140 mA; and the detection temperature was 220°C.

[0097] Test absorbent: The absorbent shown in Example 1 was used, and 7.5 L of the absorbent was used to carry out the reaction at the microinterface.

[0098] Detection steps: The decarbonized flue gas after the reaction is passed into the gas chromatograph at a rate of 100 ml / min every 1 minute to determine the CO2 concentration in the decarbonized flue gas, and then estimate the absorption rate of the absorbent per minute according to the formula.

[0099] The calculation formula is as follows:

[0100]

[0101] Where, is the amount of CO2 absorbed in 1 min; is the total amount of flue gas introduced; is the total amount of inert components in the incoming flue gas; is the proportion of inert components detected by gas chromatography.

[0102] Experimental Example 2 Measurement of CO2 load, regeneration rate, cycle capacity and regeneration energy consumption

[0103] The supersaturated rich solution obtained after treatment according to Examples 1-11 and Comparative Examples 1-7 was titrated to determine the final CO2 absorption load. The specific determination method is as follows:

[0104] Detection steps: Take 1g of supersaturated rich liquid and add it to 30g of water for absorption. Add the diluted liquid into a closed reactor connected to a gas measuring tube. Add dilute sulfuric acid to the reactor to release the absorbed CO2 from the liquid phase, and measure the change in the total gas volume in the gas measuring tube. The total CO2 load a is determined by the formula.

[0105] The calculation formula is as follows:

[0106]

[0107] Where a is the carbon dioxide load (mol / kg), mabs is the sample mass of the absorbent (kg), and are the volume changes of the gas tube and the acid burette, respectively.

[0108] The above test method is applicable not only to CO2 absorption processes, but also to CO2 regeneration processes. The regeneration rate is determined by the difference in absorbent load before and after regeneration; the circulation capacity is determined by the difference in supersaturated rich solution and regeneration lean solution.

[0109] The regeneration energy consumption is measured by an electric meter through a regeneration test on a pilot plant. The measured energy consumption consists of three parts: reaction heat, sensible heat for solution heating, and evaporation heat for water evaporation.

[0110] Testing steps: The regeneration temperature was maintained at 373.15 K, the liquid flow rate was 0 to 100 mL / min, and the gas flow rate was 0 to 30 L / min; the regeneration energy consumption was measured using an electric meter.

[0111] The final measurement results are shown in Table 1 below:

[0112]

[0113] Experimental Example 3 Determination of the molar ratio of the shuttle agent and the proton acceptor

[0114] The specific implementation steps are consistent with those in Example 11. Absorbent 1, absorbent 2, and absorbent 3 are prepared according to the molar ratios of the shuttle agent and the proton receiver of 1:1, 1:3, and 1:5, respectively. The prepared absorbents are used to decarbonize the flue gas according to the implementation steps in Example 11.

[0115] Then, the CO2 absorption rate was measured according to Experimental Example 1, and the curve graph drawn based on the measurement results is as follows: Figure 1 shown.

[0116] Therefore, Figure 1 It can be seen that the present invention explores the most suitable molar ratio by experimenting with the molar ratio between the shuttle agent and the proton receiver. When the molar ratio between the shuttle agent and the proton receiver is 1:3, the absorbent prepared by the present invention has the best absorption effect for CO2.

[0117] Experimental Example 4 Determination of the Molar Ratio of N-methylpiperazine and Monoethanolamine in the Shuttle Agent

[0118] The specific implementation steps are consistent with those of Example 11. N-methylpiperazine and monoethanolamine are prepared into shuttle agents at molar ratios of 1:3, 2:1, and 1:1, and then the shuttle agent and the proton acceptor methyldiethanolamine are prepared into absorbents 4, 5, and 6, respectively, at a molar ratio of 1:1. The prepared absorbents are used to decarbonize the flue gas according to the implementation steps of Example 11.

[0119] Then, the CO2 load was measured according to the method of measuring CO2 load in Experimental Example 2, and the curve graph drawn according to the measurement results is as follows: Figure 2 shown.

[0120] Therefore, Figure 2 It can be seen that the present invention explores the most suitable molar ratio by measuring the molar ratio of the raw materials in the shuttle agent. When the molar ratio of N-methylpiperazine and monoethanolamine in the shuttle agent is 1:1, the absorbent prepared thereby has the best absorption effect for CO2.

[0121] Experimental Example 5: Determination of the Decarburization Effect of Micro-Interface Generator

[0122] The decarbonized flue gas in Example 11 of the present invention and Comparative Example 7 was measured according to the measurement methods in Experimental Examples 1 and 2. It can be seen from the setting method in Comparative Example 7 that the only difference between Comparative Example 7 and Example 11 is that Comparative Example 7 does not introduce a microinterface generator. The specific measurement results are shown in Table 2 below.

[0123] Table 2 Effects of Example 11 and Comparative Example 7

[0124]

[0125] Therefore, from the experimental data in Table 1, we can know that

[0126] By comparing Examples 3-6, it can be seen that the selection of the shuttling agent is very important for the present invention. When the shuttling agent is a mixture of N-methylpiperazine and monoethanolamine, the absorbent prepared therefrom has an excellent absorption effect on carbon dioxide in the flue gas. This is because the reaction rate of the initial decarbonization reaction can be further improved by the mixture of the two. Monoethanolamine is used as a shuttling agent to capture carbon dioxide. It has the characteristics of high capture efficiency, large solubility, and the ability to efficiently capture carbon dioxide, and can allow carbon dioxide to be adsorbed on its surface to form a solution. However, for the process of monoethanolamine absorbing carbon dioxide, it is generally necessary to select a high concentration of monoethanolamine to ensure the absorption rate and reaction stability, so that the solution formed by monoethanolamine and carbon dioxide is not easily desorbed in subsequent operations. However, due to the certain toxicity of high-concentration monoethanolamine and the high-tech process of absorbing carbon dioxide by high-concentration monoethanolamine, it is necessary to control multiple conditions and parameters to achieve a better capture effect of carbon dioxide. The operation is difficult and not easy to control. The presence of N-methylpiperazine can reduce the use concentration of monoethanolamine and improve the stability of the solution formed by the combination of monoethanolamine and carbon dioxide, so that the solution formed by the combination of monoethanolamine and carbon dioxide is not easy to desorb in the subsequent operation process, thereby affecting the capture effect of the absorbent on carbon dioxide; and N-methylpiperazine itself also has a certain capture effect on carbon dioxide. Therefore, the combination of the two can further improve the removal of carbon dioxide by absorption, and maintain stability, and is not easy to desorb in the subsequent operation process.

[0127] Comparison of Examples 6-8 and Comparative Examples 1-2 also reveals that the molar ratio of N-methylpiperazine to monoethanolamine in the shuttling agent is also very important for the present invention. This is because, in the present invention, the shuttling agent is primarily used to increase the reaction rate of the initial decarbonization reaction and further enhance the activity of the proton acceptor. The proton acceptor ensures that the carbon dioxide sites on the shuttling agent are not occupied by other substances, thereby affecting the shuttling agent's carbon dioxide capture efficiency. Therefore, the molar ratio of N-methylpiperazine to monoethanolamine in the shuttling agent is crucial. This is because when the molar ratio of N-methylpiperazine to monoethanolamine is (2:1) to (1:3), preferably 1:1, the absorbent prepared by mixing the two has excellent carbon dioxide capture efficiency. This mixture also has the best effect on increasing the rate of the decarbonization reaction. In addition, the rich liquid formed after carbon dioxide capture has more stable properties and is less likely to decompose during subsequent operations. If there is too much N-methylpiperazine in the absorbent, the carbon dioxide capture effect of the absorbent prepared will be affected. If there is too much monoethanolamine, the solution formed after it combines with carbon dioxide will be unstable, and it will be easy to decompose in subsequent operations, thereby causing carbon dioxide to be released prematurely.

[0128] Comparison of Examples 9-11 shows that the selection of a proton absorber is also very important for the present invention. This is because when a new round of flue gas is introduced into the rich liquid and enters the micro-interface generator together, the flue gas is broken into microbubbles. Under the influence of drag, the microbubbles can move forward synchronously with the rich liquid to form a uniform gas-liquid mixture. This generates a free radical effect. At this time, in order to prevent the shuttle agent from combining with the generated free radicals, resulting in the occupation of the sites on the shuttle agent belonging to carbon dioxide, which affects its capture efficiency, while also ensuring that it has excellent carbon dioxide capture efficiency, the present invention selects one or more of diethanolamine, diisopropanolamine, triethanolamine, and methyldiethanolamine as the proton absorber. Methyldiethanolamine is preferably used because it has a strong ability to bind to free radicals and can absorb more free radicals, thereby preventing free radicals from occupying the sites on the shuttle agent belonging to carbon dioxide. The combination of the proton absorber and the shuttle agent can further enhance the shuttle agent's carbon dioxide capture efficiency and also enhance the activity of the proton absorber.

[0129] By comparing Example 11 with Comparative Examples 3-4, it can be seen that the molar ratio of the shuttle agent and the proton receiver is very important for the present invention. This is because in the present invention, the shuttle agent and the proton receiver are mainly mixed to form an absorbent, and the flue gas is preliminarily decarbonized by the absorbent to form a rich liquid, and then the flue gas is introduced into the rich liquid and enters the micro-interface generator together to form a uniform gas-liquid mixture, thereby further realizing the capture of carbon dioxide in the flue gas. The shuttle agent itself acts as a rate promoter and also has a certain carbon dioxide capture effect, and can also improve the activity of the proton receiver, which can accelerate the capture rate of CO2 and further improve the reaction rate when the flue gas is preliminarily decarbonized. Then, after the preliminarily decarbonized flue gas is introduced into the rich liquid obtained and enters the micro-interface generator together to form a stable gas-liquid mixture. At this time, the presence of the shuttle agent can further improve the proton The activity of the receptor is increased because the reduction in bubble size produces a free radical effect, which causes the chemical bonds in the solution to break and form hydroxyl radicals and protons. Due to the presence of the proton receptor, the protons and hydroxyl radicals formed after these breaks will interact with the proton receptor, thereby preventing them from combining with the shuttle agent and occupying the sites on the shuttle agent that belong to carbon dioxide, reducing its carbon dioxide capture effect. During the initial decarbonization of flue gas, the presence of the shuttle agent can cause carbonic acid to exist in the rich liquid obtained after the initial decarbonization. Due to the instability of carbonic acid itself, it will decompose to produce hydrogen ions and bicarbonate ions. The hydrogen ions can also combine with the proton receptor to enhance the activity of the proton receptor. Moreover, due to the presence of the proton receptor, during the initial decarbonization of flue gas, the hydrogen ions will not combine with the shuttle agent to occupy the sites of carbon dioxide, reducing its carbon dioxide capture effect. Therefore, in the present invention, by combining the shuttle agent and the proton receptor, the activity of the proton receptor is enhanced by the shuttle agent, and the presence of the proton receptor can also ensure that the carbon dioxide capture effect of the shuttle agent is not affected. In summary, for the present invention, the molar ratio of the shuttle agent to the proton acceptor is very important. In the decarbonization method of the present invention, if there is too much shuttle agent, the amount of proton acceptor will be correspondingly reduced, so that the sites on the shuttle agent belonging to carbon dioxide are occupied by a portion of hydrogen ions, which affects the shuttle agent's carbon dioxide capture effect and also affects the reaction rate. If there is too little shuttle agent, there will be too much proton acceptor, and the activity of a portion of the proton acceptor cannot be enhanced. In addition, too little shuttle agent will reduce the reaction rate of the initial decarbonization, and its capture of carbon dioxide in the flue gas will also be correspondingly reduced.

[0130] By comparing Example 1 and Comparative Examples 5-6, it can be seen that the diameter size of the microbubbles is very important for the present invention. This is because only when the size of the microbubbles is within an appropriate range can the flue gas and the rich liquid form a stable gas-liquid mixture by reducing the bubble size to produce a free radical effect and an interfacial electric field effect, thereby enabling the absorbent to reach a higher load, and the activity of the absorbent is increased by the free radical effect, thereby reducing the total energy consumption of the process. Therefore, for the present invention, when the diameter of the microbubbles is 100-300 μm, the free radical effect generated by the microbubbles is excellent for improving the activity of the absorbent, thereby achieving a better absorption effect of carbon dioxide through the absorbent. If the diameter of the microbubbles is too large, the bubbles will be too large to produce the free radical effect and the interfacial electric field effect, so that the activity of the absorbent cannot be improved, thereby affecting the decarbonization effect of the flue gas; if the microbubbles are too small, the flue gas and the rich liquid will not be able to form a stable gas-liquid mixture.

[0131] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A CO2 absorbent, characterized in that The absorbent is mainly composed of a shuttle agent and a proton receiver; the molar ratio of the shuttle agent to the proton receiver is 1:3; The shuttling agent is a mixture of N-methylpiperazine and monoethanolamine; The molar ratio of N-methylpiperazine to monoethanolamine in the shuttle agent is (2:1)-(2:3); The proton acceptor is one of diethanolamine, diisopropanolamine, triethanolamine and methyldiethanolamine.

2. The absorbent according to claim 1, characterized in that The molar ratio of N-methylpiperazine to monoethanolamine in the shuttle agent is 1:

1.

3. The absorbent according to claim 1, characterized in that The proton acceptor is methyldiethanolamine.

4. A method for enhanced amine flue gas decarbonization using the CO2 absorbent according to any one of claims 1 to 3, characterized in that: The following steps are involved: Prepare absorbent and preheat the absorbent; Flue gas is introduced into the preheated absorbent to carry out decarbonization reaction to obtain rich liquid; The flue gas that has been broken into microbubbles is introduced into the rich liquid again to obtain a gas-liquid mixture; The supersaturated rich liquid is subjected to gas-liquid separation and regeneration to obtain high-purity CO2.

5. The decarbonization method according to claim 4, characterized in that The diameter of the microbubbles is micron-sized bubbles of 100-300 μm.

6. The decarbonization method according to claim 5, characterized in that: The diameter of the microbubbles is 300 μm.

7. A flue gas decarbonization system using the CO2 absorbent according to any one of claims 1 to 3 and the flue gas decarbonization method according to claim 4, characterized in that: The process comprises a gas washing tower, a micro-interface reaction tower, a gas-liquid separation tank and a regeneration tower which are connected in sequence.

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