CO2 absorbent, enhanced amine method flue gas decarburization method and decarburization device

Abstract

The invention provides a CO2 absorbent, an enhanced amine method flue gas decarburization method and a decarburization device. The absorbent is mainly composed of a shuttling agent and a proton receiving agent. Preferably, the molar ratio of the shuttle agent to the proton receiving agent is (1: 1)-(1: 5); preferably, the molar ratio of the shuttle agent to the proton receiving agent is 1: 3. According to the invention, the absorbent is configured, the flue gas broken into the microbubbles is introduced into the absorbent, and the microbubbles can advance synchronously with the liquid phase under the influence of drag force so as to form a uniform gas-liquid mixture, so that the cyclic load of the absorbent is improved, the total energy consumption in the decarburization process is reduced, and the removal effect of CO2 is improved.

Description

Technical Field

[0001] The 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 CCUS (carbon capture, utilization and storage), amine / ammonia decarbonization technology is widely used, especially in the capture and utilization of large-scale flue gas carbon sources. However, in actual operation, most decarbonization methods have a slow capture rate for carbon dioxide and their CO 2 The capture effect is poor and the regeneration energy consumption is high. Therefore, how to effectively reduce the regeneration energy consumption and achieve higher CO 2 Capture effect and capture rate are the 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 CO 2 The absorbent is a combination of a shuttle agent and a proton acceptor, which accelerates the CO 2 The capture rate of the shuttle agent can be increased by combining it with a proton acceptor, thereby increasing the capture rate of the shuttle agent and achieving higher CO 2 absorption capacity.

[0005] The second object of the present invention is to provide an enhanced amine flue gas decarbonization method, which comprises configuring an absorbent and introducing flue gas 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 circulating load of the absorbent is increased, thereby reducing the total energy consumption of the decarbonization process and improving CO 2 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 particularly adopted: A CO 2 An absorbent, wherein the absorbent is mainly composed of a shuttle agent and a proton receiving agent; Preferably, the molar ratio of the shuttling agent to the proton acceptor is 1:1-1:5; Preferably, the molar ratio of the shuttling agent to the proton acceptor is 1:3.

[0008] In the present invention, the configuration of the absorbent is very important for the present invention. This is because in the process of the present invention of the initial decarbonization of flue gas, the shuttle agent itself acts as a rate accelerator and also has a certain carbon dioxide capture effect, and can also enhance the activity of the proton receiving agent, which can accelerate the CO 2 The capture speed is increased to further improve the reaction rate during the initial decarbonization of the flue gas. Then, the rich liquid obtained after the initial decarbonization is introduced into the flue gas. At this time, the flue gas is broken into microbubbles. Under the influence of drag force, the microbubbles can move forward synchronously with the rich liquid to form a uniform gas-liquid mixture. At this time, the presence of the shuttle agent can further improve the activity of the proton receiver. This is because the reduction of the bubble size will produce a free radical effect, which causes the chemical bonds in the solution to break to form hydroxyl radicals and hydrogen radicals. Hydrogen radicals promote CO 2 Chemical dissolution and forming protons, due to the presence of the proton receiver, these protons and hydroxyl radicals formed after the fracture will interact with the proton receiver, thereby preventing it from combining with the shuttle agent, occupying the sites of carbon dioxide on the shuttle agent, and reducing its capture effect on carbon dioxide. When the flue gas is initially decarbonized, the presence of the shuttle agent can make carbonic acid exist in the rich liquid obtained after the initial decarbonization, and due to the instability of carbonic acid itself, it will decompose to produce hydrogen ions and bicarbonate ions, and the hydrogen ions can also combine with the proton receiver to enhance the activity of the proton receiver, and due to the presence of the proton receiver, when the flue gas is initially decarbonized, the hydrogen ions will not combine with the shuttle agent to occupy the sites of carbon dioxide, reducing its capture effect on carbon dioxide. Therefore, in the present invention, the shuttle agent and the proton receiver are matched, the activity of the proton receiver is enhanced by the shuttle agent, and the presence of the proton receiver can also make the capture effect of the shuttle agent on carbon dioxide unaffected. In summary, for the present invention, the molar ratio of the shuttling agent and the proton acceptor is very important. In the decarbonization method of the present invention, if there is too much shuttling agent, the amount of the proton acceptor will be reduced accordingly, so that the sites belonging to carbon dioxide on the shuttling agent are occupied by a part of hydrogen ions, which affects the capture effect of the shuttling agent on carbon dioxide and also affects the reaction rate. If there is too little shuttling agent, there will be too much proton acceptor, and the activity of a part of the proton acceptor cannot be improved. In addition, too little shuttling agent will reduce the reaction rate of the initial decarbonization, and its capture of carbon dioxide in the flue gas will also be reduced accordingly.

[0009] Preferably, as a further feasible scheme, the shuttling agent is one or more of 2-amino-2-methyl-1-propanol, monoethanolamine, piperazine, N-methylpiperazine, benzylamine and piperidine.

[0010] Preferably, as a further feasible solution, the shuttling agent is a mixture of N-methylpiperazine and monoethanolamine.

[0011] In the present invention, by selecting one or more of 2-amino-2-methyl-1-propanol, monoethanolamine, piperazine, N-methylpiperazine, benzylamine and piperidine as the shuttling agent, and preferably selecting a mixture of N-methylpiperazine and monoethanolamine as the shuttling agent, the configured absorbent has a better carbon dioxide capture effect, and through the mixture of the two, the reaction rate of the initial decarbonization reaction can be further improved. 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 make carbon dioxide 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 in the 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 conditions and parameters in multiple aspects in order 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 concentration of monoethanolamine used 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. In addition, 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.

[0012] Preferably, as a further implementable solution, the molar ratio of N-methylpiperazine to monoethanolamine in the shuttling agent is (2:1)-(1:3).

[0013] Preferably, as a further implementable scheme, the molar ratio of N-methylpiperazine to monoethanolamine in the shuttling agent is 1:1.

[0014] In the present invention, the molar ratio of N-methylpiperazine and monoethanolamine in the shuttle agent is crucial, because when the molar ratio of N-methylpiperazine to monoethanolamine is (2:1)-(1:3), preferably 1:1, the absorbent obtained by mixing the two has an excellent carbon dioxide capture effect, and the mixture of the two is also the best for increasing the rate of the decarbonization reaction, and the rich liquid formed after capturing carbon dioxide has a more stable property, and is not easy to decompose in subsequent operations. Therefore, if there is too much N-methylpiperazine in the absorbent, the absorbent prepared by it affects the carbon dioxide capture effect, and if there is too much monoethanolamine, the solution formed by it and carbon dioxide will be unstable, and decomposition will easily occur in subsequent operations, thereby causing carbon dioxide to be released prematurely.

[0015] Preferably, as a further feasible solution, the proton acceptor is one or more of diethanolamine, diisopropanolamine, triethanolamine and methyldiethanolamine.

[0016] Preferably, as a further feasible solution, the proton acceptor is methyldiethanolamine.

[0017] 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: A method for enhanced amine-based flue gas decarbonization comprises the following steps: Prepare absorbent and preheat the absorbent; Flue gas is introduced into the preheated absorbent to perform a decarbonization reaction to obtain a rich liquid; The flue gas 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 CO 2 .

[0018] In the scheme of the present invention, an absorbent is first prepared, and then flue gas is introduced into the absorbent for a preliminary decarbonization reaction. In this preliminary decarbonization process, the absorbent can react with CO in the flue gas. 2 During this initial decarbonization process, the absorbent 2 There is a certain limit to the enrichment of CO. Therefore, the present invention has found through a series of creative work that by using the absorbent provided by the present invention, CO 2 After the initial decarbonization, the load of the extra absorbent rich liquid is the load of the traditional production process. In the present invention, the flue gas broken into microbubbles is introduced into the rich liquid. 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 circulating load of the absorbent is increased, thereby reducing the total energy consumption of the decarbonization process and improving CO 2The diameter of the microbubbles ranges from 100 to 300 μm. This method can further enhance the activity of the absorbent, increase the circulating load of the reaction solution, and improve its efficiency in removing CO. 2 The enrichment effect makes it have a more excellent decarbonization performance and can further reduce the regeneration energy consumption. The load of the supersaturated rich liquid finally obtained is at least 1.2 times the load of the rich liquid obtained after the initial decarbonization. This is because, in the present invention, the rich liquid obtained 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 free radicals and hydroxyl free radicals. The hydrogen free radicals can promote CO 2 The hydroxyl radicals will interact with the absorbent through the dissolution. The combination of the two can enhance the activity of the proton receiver, so that the proton receiver can further accept more dissolved carbon dioxide, and finally achieve the increase of load.

[0019] Preferably, as a further implementable solution, the diameter of the microbubbles is a micron-sized bubble of 100-300 μm; Preferably, the diameter of the microbubbles is 300 μm.

[0020] In the present invention, the size of microbubbles is very important, because only when the size of microbubbles is within a suitable range can the gas-liquid mixture formed by flue gas and rich liquid produce free radical effect and interfacial electric field effect by reducing the bubble size, so that the absorbent can reach a higher load, and the activity of the absorbent is improved 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, and then the absorbent achieves a better absorption effect of carbon dioxide. If the diameter of the microbubbles is too large, the bubbles will be too large to produce free radical effect and 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 rich liquid will not be able to form a stable gas-liquid mixture after mixing.

[0021] 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: It includes a gas washing tower, a micro-interface reaction tower, a gas-liquid separation tank and a regeneration tower which are connected in sequence.

[0022] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention provides an absorbent which combines a shuttle agent and a proton acceptor, and accelerates the CO 2 The capture rate of the shuttle agent can be increased by combining it with a proton acceptor, thereby increasing the capture rate of the shuttle agent and achieving higher CO 2 absorption capacity.

[0023] (2) The present invention provides an enhanced amine flue gas decarbonization method, which comprises preparing an absorbent, and then introducing flue gas broken into microbubbles into the absorbent to form a uniform gas-liquid mixture, thereby improving the activity of the absorbent, and increasing the circulating load of the absorbent, reducing the total energy consumption of the decarbonization process, and improving CO 2 removal effect.

[0024] (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

[0025] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Moreover, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings: Figure 1 The present invention is a curve chart drawn according to the measurement results of Experimental Example 3; Figure 2 This is a curve chart drawn according to the measurement results of Experimental Example 4 of the present invention. DETAILED DESCRIPTION

[0026] 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. If specific conditions are not specified in the embodiments, they are carried out according to normal conditions or conditions recommended by the manufacturer. If the manufacturer is not specified in the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0027] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0028] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0029] In order to more clearly explain the technical solution of the present invention, it is described in the form of specific embodiments below.

[0030] Example 1 The implementation steps of the decarbonization method are as follows: 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, the temperature is increased to 40° C., the absorbent is preheated, and then introduced into a gas scrubber for a preliminary decarbonization reaction; After the initial decarbonization, the flue gas 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; A new round of flue gas is introduced into the rich liquid and then into the micro-interface generator, and micro-bubbles with a diameter of 100 μm are produced by adjusting the micro-interface generator tower to form a stable gas-liquid mixture; The gas-liquid mixture naturally overflows into the micro-interface reaction tower for further flue gas decarbonization reaction to generate supersaturated rich liquid; 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 CO 2 gas.

[0031] Example 2 The implementation steps of the decarbonization method are as follows: 2-amino-2-methyl-1-propanol and diethanolamine are prepared as an absorbent in a molar ratio of 1:5, and then the prepared absorbent is preheated, the temperature is increased to 40° C., the absorbent is preheated, and then introduced into a gas scrubber for a preliminary decarbonization reaction; After the initial decarbonization, the flue gas 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; A new round of flue gas is introduced into the rich liquid and then into the micro-interface generator, and micro-bubbles with a diameter of 600 μm are produced by adjusting the micro-interface generator tower to form a stable gas-liquid mixture; The gas-liquid mixture naturally overflows into the micro-interface reaction tower for further flue gas decarbonization reaction to generate supersaturated rich liquid; 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 CO 2 gas.

[0032] Example 3 The implementation steps of the decarbonization method are as follows: 2-amino-2-methyl-1-propanol and diethanolamine are prepared as an absorbent in a molar ratio of 1:3, and then the prepared absorbent is preheated, the temperature is increased to 40° C., the absorbent is preheated, and then introduced into a gas scrubber for a preliminary decarbonization reaction; After the initial decarbonization, the flue gas 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; A new round of flue gas is introduced into the rich liquid and then into the micro-interface generator, and micro-bubbles with a diameter of 500 μm are produced by adjusting the micro-interface generator tower to form a stable gas-liquid mixture; The gas-liquid mixture naturally overflows into the micro-interface reaction tower for further flue gas decarbonization reaction to generate supersaturated rich liquid; 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 CO 2 gas.

[0033] Example 4 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 to the proton acceptor diethanolamine remains unchanged.

[0034] Example 5 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 N-methylpiperazine.

[0035] Example 6 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.

[0036] Example 7 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.

[0037] Example 8 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.

[0038] Example 9 The specific implementation steps are the same as those in Example 8, except that the proton acceptor diethanolamine is replaced by diisopropanolamine.

[0039] Example 10 The specific implementation steps are the same as those in Example 8, except that the proton acceptor diethanolamine is replaced by triethanolamine.

[0040] Embodiment 11 The specific implementation steps are the same as those in Example 8, except that the proton acceptor diethanolamine is replaced by methyldiethanolamine.

[0041] Comparative Example 1 The specific implementation steps are the same as those in Example 11, except that the N-methylpiperazine and monoethanolamine in the shuttling agent are mixed at a molar ratio of 0.5:1.

[0042] Comparative Example 2 The specific implementation steps are the same as those in Example 11, except that the N-methylpiperazine and monoethanolamine in the shuttling agent are mixed at a molar ratio of 1:6.

[0043] Comparative Example 3 The specific implementation steps are the same as those of Example 11, except that the molar ratio of the mixture of the shuttling agent N-methylpiperazine and monoethanolamine and the proton acceptor methyldiethanolamine is adjusted to 0.5:1.

[0044] Comparative Example 4 The specific implementation steps are the same as those of Example 11, except that the molar ratio of the mixture of the shuttling agent N-methylpiperazine and monoethanolamine and the proton acceptor methyldiethanolamine is adjusted to 3:1.

[0045] Comparative Example 5 The specific implementation steps are the same as those in Example 11, except that the diameter of the microbubbles is adjusted to 50 μm.

[0046] Comparative Example 6 The specific implementation steps are the same as those in Example 11, except that the diameter of the microbubbles is adjusted to 800 μm.

[0047] Comparative Example 7 The specific implementation steps are consistent with Example 11, except that after a new round of flue gas is introduced into the rich liquid, it is not broken into microbubbles, that is, it is not used, but is directly introduced into the microinterface reaction tower for decarbonization reaction.

[0048] Experimental Example 1 CO 2 Absorption rate determination The preset feed gas was processed according to the implementation scheme of Examples 1-11 and Comparative Examples 1-7, and finally CO 2 The absorption rate is measured by gas chromatography, wherein the micro-interface generator used is a gas-liquid follower micro-interface generator, and the specific measurement method is as follows; Chromatographic conditions: the detector is a thermal conductivity detector (TCD); the chromatographic column is an activated carbon column; the detection current is 140 mA; and the detection temperature is 220°C.

[0049] 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.

[0050] Detection steps: The decarbonized flue gas after the reaction was passed into the gas chromatograph at a rate of 100 ml / min every 1 minute to determine the CO 2 Concentration, and then estimate the absorption rate of the absorbent per minute according to the formula.

[0051] The calculation formula is as follows:

[0052] In the formula, is the CO absorbed in 1 min 2 quantity; is the total amount of flue gas introduced; is the total amount of inert components in the incoming flue gas; It is the ratio of inert components detected by gas chromatography.

[0053] Experimental Example 2 CO 2 Determination of load, regeneration rate, cycle capacity and regeneration energy consumption The supersaturated rich solution obtained after treatment according to Examples 1-11 and Comparative Examples 1-7 was titrated to determine the final CO 2 The specific determination method of the absorption load is as follows: Detection steps: Take 1g of supersaturated rich liquid and add it into 30g of water for absorption. Add the diluted liquid into a closed reactor connected to a gas measuring pipe, and drop dilute sulfuric acid into the reactor to make the absorbed CO 2 Released from the liquid phase, and the total gas volume change in the gas tube is measured, and the CO is determined by the formula 2 The total load a.

[0054] The calculation formula is as follows:

[0055] 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.

[0056] The above test method is not only applicable to CO 2 The absorption process can also be applied to CO 2 Regeneration process. The regeneration rate is determined by the difference ratio of the absorbent load before and after regeneration; the circulation capacity is determined by the difference between the supersaturated rich liquid and the regeneration lean liquid.

[0057] 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.

[0058] Test 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 ammeter.

[0059] The final measured results are shown in Table 1 below:

[0060] Experimental Example 3 Determination of the molar ratio of the shuttle agent and the proton acceptor The specific implementation steps are consistent with Example 11, and absorbent 1, absorbent 2 and absorbent 3 are prepared according to the molar ratio of the shuttle agent to the proton receiving agent of 1:1, 1:3 and 1:5 respectively, and the prepared absorbents are used to decarbonize the flue gas according to the implementation steps in Example 11; Then, according to Experimental Example 1, CO 2 The absorption rate is measured, and the curve graph drawn according to the measurement results is as follows Figure 1 shown.

[0061] Therefore, Figure 1It 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 acceptor. When the molar ratio between the shuttle agent and the proton acceptor is 1:3, the absorbent prepared by the present invention has a good absorption capacity for CO 2 The absorption effect is optimal.

[0062] Experimental Example 4 Determination of the molar ratio of N-methylpiperazine and monoethanolamine in the shuttling agent The specific implementation steps are consistent with Example 11, wherein N-methylpiperazine and monoethanolamine are configured to form a shuttle agent at a molar ratio of 1:3, 2:1, and 1:1, and then the shuttle agent and the proton receiving agent methyldiethanolamine are configured to form absorbent 4, absorbent 5, and absorbent 6 at a molar ratio of 1:1, respectively, and the configured absorbents are used to decarbonize the flue gas according to the implementation steps in Example 11; Then, according to Experimental Example 2, CO 2 Loading method for CO 2 The load is measured, and the curve graph drawn according to the measurement results is as follows Figure 2 shown.

[0063] Therefore, Figure 2 It can be seen from the figure that the present invention explores the most suitable molar ratio by measuring the molar ratio of the raw materials in the shuttling agent. When the molar ratio of N-methylpiperazine to monoethanolamine in the shuttling agent is 1:1, the absorbent prepared by the method has a good absorption capacity for CO 2 The absorption effect is optimal.

[0064] Experimental Example 5 Determination of the decarburization effect of the micro-interface generator The decarbonized flue gas in Example 11 of the present invention and Comparative Example 7 was taken, and the decarbonized flue gas 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.

[0065] Table 2 Effects of Example 11 and Comparative Example 7

[0066] Therefore, from the experimental data in Table 1, we can know that By comparing Examples 3-6, it can be known 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 by the shuttling agent has excellent absorption effect on carbon dioxide in flue gas. This is because the reaction rate of the initial decarbonization reaction can be further improved by mixing the two. Monoethanolamine is used as a shuttling agent to capture carbon dioxide. It has the characteristics of high capture efficiency, high solubility, and high efficiency in capturing carbon dioxide. It can make carbon dioxide 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 desorb in subsequent operations. However, due to the toxicity of high-concentration monoethanolamine and the high-concentration monoethanolamine absorption of carbon dioxide process technology, it is necessary to control multiple conditions and parameters to achieve a better capture effect of carbon dioxide. The operation is difficult and difficult 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 enhance the removal of carbon dioxide by absorption, and maintain stability, and is not easy to desorb in the subsequent operation process.

[0067] By comparing Examples 6-8 and Comparative Examples 1-2, it can be seen 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 reaction rate of the initial decarbonization reaction is mainly improved by the shuttling agent, and the activity of the proton acceptor can be further improved. The proton acceptor can ensure that the sites belonging to carbon dioxide on the shuttling agent are not occupied by other substances, thereby affecting the capture effect of carbon dioxide by the shuttling agent. Therefore, the molar ratio of N-methylpiperazine to monoethanolamine in the shuttling agent is very important. This is because when the molar ratio of N-methylpiperazine to monoethanolamine is (2:1)-(1:3), preferably 1:1, the absorbent prepared by mixing the two has an excellent carbon dioxide capture effect, and the mixture of the two is also the best for improving the rate of the decarbonization reaction. In addition, the rich liquid formed after capturing carbon dioxide has a more stable property and is not easy to decompose in 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 is easy to decompose in subsequent operations, thereby releasing carbon dioxide prematurely.

[0068] By comparing Examples 9-11, it can be known that the selection of the proton receiver 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. The microbubbles are affected by the drag force and can move forward synchronously with the rich liquid to form a uniform gas-liquid mixture. In this way, a free radical effect will be generated. At this time, in order to avoid the shuttle agent from combining with the generated free radicals, resulting in the occupation of the sites belonging to carbon dioxide on the shuttle agent, affecting its capture effect, it is also necessary to ensure that it has an excellent carbon dioxide capture effect. Therefore, the present invention selects one or more of diethanolamine, diisopropanolamine, triethanolamine and methyldiethanolamine as the proton receiver. When methyldiethanolamine is preferably used, it has a strong ability to combine with free radicals and can absorb more free radicals to avoid free radicals occupying the sites belonging to carbon dioxide on the shuttle agent, so that the combination of the proton receiver and the shuttle agent can further enhance the capture effect of the shuttle agent for carbon dioxide, and the shuttle agent can also play an effect on improving the activity of the proton receiver.

[0069] By comparing Example 11 with Comparative Examples 3-4, it can be seen that the molar ratio of the shuttling agent and the proton receiving agent is very important for the present invention. This is because in the present invention, the shuttling agent and the proton receiving agent are mixed to form an absorbent, and the flue gas is initially 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 shuttling agent itself acts as a rate accelerator and also has a certain carbon dioxide capture effect, and can also improve the activity of the proton receiving agent, which can accelerate CO 2The capture speed is increased, and the reaction rate of the initial decarbonization of the flue gas is further improved. Then, after the initial decarbonization is completed, the flue gas is introduced into the rich liquid and enters the microinterface generator together to form a stable gas-liquid mixture. At this time, the presence of the shuttle agent can further improve 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 protons. Due to the presence of the proton receiver, the protons and hydroxyl radicals formed after the break will interact with the proton receiver, thereby preventing it from combining with the shuttle agent and occupying The sites on the shuttle agent that belong to carbon dioxide reduce its capture effect on carbon dioxide. When the flue gas is initially decarbonized, 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 receiver to increase the activity of the proton receiver. In addition, due to the presence of the proton receiver, when the flue gas is initially decarbonized, the hydrogen ions will not combine with the shuttle agent to occupy the sites of carbon dioxide, thereby reducing its capture effect on carbon dioxide. Therefore, in the present invention, the shuttle agent and the proton receiver are matched, the activity of the proton receiver is increased by the shuttle agent, and the presence of the proton receiver can also make the capture effect of the shuttle agent on carbon dioxide unaffected. In summary, for the present invention, the molar ratio of the shuttling agent and the proton acceptor is very important. In the decarbonization method of the present invention, if there is too much shuttling agent, the amount of the proton acceptor will be reduced accordingly, so that the sites belonging to carbon dioxide on the shuttling agent are occupied by a part of hydrogen ions, which affects the capture effect of the shuttling agent on carbon dioxide and also affects the reaction rate. If there is too little shuttling agent, there will be too much proton acceptor, and the activity of a part of the proton acceptor cannot be improved. In addition, too little shuttling agent will reduce the reaction rate of the initial decarbonization, and its capture of carbon dioxide in the flue gas will also be reduced accordingly.

[0070] By comparing Example 1 and Comparative Examples 5-6, it can be seen that for the present invention, the diameter size of the microbubbles is very important. This is because only when the size of the microbubbles is within a suitable range can the flue gas and the rich liquid form a stable gas-liquid mixture, which can produce free radical effect and interfacial electric field effect by reducing the bubble size, so that the absorbent can reach a higher load, and the activity of the absorbent is improved 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, and then the absorbent achieves a better absorption effect of carbon dioxide. If the diameter of the microbubbles is too large, the bubbles will be too large to produce free radical effect and 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.

[0071] 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 aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned 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 receiving agent; Preferably, the molar ratio of the shuttling agent to the proton acceptor is 1:1-1:5; Preferably, the molar ratio of the shuttling agent to the proton acceptor is 1:

3.

2. The absorbent according to claim 1, characterized in that The shuttling agent is one or more of 2-amino-2-methyl-1-propanol, monoethanolamine, piperazine, N-methylpiperazine, benzylamine and piperidine.

3. The absorbent according to claim 2, characterized in that The shuttling agent is a mixture of N-methylpiperazine and monoethanolamine.

4. The absorbent according to claim 3, characterized in that The molar ratio of N-methylpiperazine to monoethanolamine in the shuttle agent is (2:1)-(1:3).

5. The absorbent according to claim 4, characterized in that The molar ratio of N-methylpiperazine to monoethanolamine in the shuttling agent is 1:

1.

6. The absorbent according to claim 1, characterized in that The proton acceptor is one or more of diethanolamine, diisopropanolamine, triethanolamine and methyldiethanolamine.

7. The absorbent according to claim 6, characterized in that The proton acceptor is methyldiethanolamine.

8. A method for enhanced amine flue gas decarbonization using the CO2 absorbent according to any one of claims 1 to 7, characterized in that: The following steps are involved: Prepare absorbent and preheat the absorbent; Flue gas is introduced into the preheated absorbent to perform a decarbonization reaction to obtain a rich liquid; The flue gas 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.

9. The decarbonization method according to claim 8, characterized in that: The diameter of the microbubbles is micron-sized bubbles of 100-300 μm; Preferably, the diameter of the microbubbles is 300 μm.

10. A flue gas decarbonization system using the CO2 absorbent according to any one of claims 1 to 7 and the flue gas decarbonization method according to claim 9, characterized in that: It includes 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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