Method and system for compounding ionic liquid prepared by electrochemical method and alkylol amine to absorb carbon dioxide

Abstract

The invention discloses a method and a system for compounding ionic liquid and chain alcohol amine prepared by an electrochemical method to absorb carbon dioxide. The method comprises the following steps: S1, pretreating to-be-treated waste gas containing carbon dioxide, and conveying the pretreated waste gas to a carbon dioxide absorption tower; s2, preparing an ionic liquid-chain alcohol amine composite absorbent; S3, introducing the composite absorbent into a carbon dioxide absorption tower, and carrying out carbon dioxide absorption treatment; s4, the residual ionic liquid-chain alcohol amine composite absorbent in the carbon dioxide absorption tower is output for regeneration and then enters the carbon dioxide absorption tower again. The composite absorbent is good in absorption capacity and high in absorption rate, the viscosity of a system is reduced, equipment corrosion can be avoided to a certain extent, and the CO2 loading capacity limited by corrosion / degradation is improved; the regeneration temperature is reduced; by separating the CO2 capture product, the regeneration volume can be reduced, and the regeneration energy can be reduced.

Description

Technical Field

[0001] The invention relates to the technical field of waste gas treatment, and in particular to a method and system for preparing ionic liquid by electrochemical method and compounding with chain alcohol amine to absorb carbon dioxide. Background Art

[0002] Among the existing CO2 capture technologies, the most commonly used is chemical absorption, which uses organic amines such as monoethanolamine (MEA), diethanolamine, N-methyldiethanolamine, etc. as absorbents. It has the advantages of low cost, mature technology, and high capture efficiency, but it also has problems such as low gas load, high capture energy consumption, solvent degradation / evaporation, and equipment corrosion. One of the main disadvantages of the technology based on water-chain alcohol amines is the high regeneration requirements. In power plants, carbon dioxide capture and storage (CCS) requires up to 40% additional energy, of which about 50% is consumed in the regeneration step.

[0003] Ionic liquids have excellent properties such as negligible vapor pressure, low heat capacity, adjustable structure and good affinity for CO2. However, compared with traditional organic amine solutions, the CO2 absorption capacity of physically absorbed ionic liquids is lower and they have higher viscosity after absorbing CO2, which limits the application of functionalized ionic liquids.

[0004] The synthesis of ionic liquids mostly adopts two-step and one-step synthesis methods. In the two-step and one-step synthesis methods, a large amount of solvent is generally required to prepare ionic liquids. Since the reaction needs to be heated and refluxed, the heating time is relatively long. The auxiliary synthesis method has the microwave radiation method. The advantage of the auxiliary method is that it does not require organic solvents, can significantly shorten the reaction time of ionic liquids, improve the yield, and effectively avoid environmental pollution. The biggest disadvantage is that the reaction is not easy to control, there are side reactions, and microwave radiation may also cause harm to the human body. The traditional synthesis method inevitably contains a small amount (about 5%) of halogen ions, and will produce by-products of equal mass, affecting its normal use.

[0005] Therefore, it is necessary to improve the existing technology to provide a more reliable solution. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a method and system for preparing ionic liquid and chain alcohol amine by electrochemical method to absorb carbon dioxide in view of the deficiencies in the above-mentioned prior art.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is as follows: In the first aspect of the present invention, a method for preparing an ionic liquid and a chain alcohol amine for absorbing carbon dioxide by an electrochemical method is provided, comprising the following steps:

[0008] S1, transporting the waste gas containing carbon dioxide to be treated to a carbon dioxide absorption tower after pretreatment;

[0009] S2. Preparation of ionic liquid-alkanolamine composite absorbent:

[0010] The anode raw material containing the target cation is put into the anode of the electrolytic cell, and the cathode raw material containing the target anion is put into the cathode of the electrolytic cell. The target cation passes through the cation exchange membrane and forms an ionic liquid with the target anion passing through the anion exchange membrane under electrolysis. The ionic liquid is then mixed with the introduced chain alcohol amine solution to obtain a liquid ionic liquid-chain alcohol amine composite absorbent for absorbing carbon dioxide;

[0011] S3, passing the ionic liquid-alkanolamine composite absorbent into a carbon dioxide absorption tower to absorb the carbon dioxide;

[0012] S4, the ionic liquid-alkanolamine composite absorbent in the carbon dioxide absorption tower forms a solid urethane product with carbon dioxide, and the residual ionic liquid-alkanolamine composite absorbent in the carbon dioxide absorption tower is separated from the solid urethane product and then output for regeneration, and then mixed with the new ionic liquid-alkanolamine composite absorbent prepared in step S2 and re-enters the carbon dioxide absorption tower.

[0013] Preferably, the pretreatment method of the waste gas to be treated is: the waste gas to be treated is first sprayed through a spray tower, and then dusted.

[0014] Preferably, the residual ionic liquid-alkanolamine composite absorbent in step S4 is transported to an absorbent regeneration device for heating to achieve regeneration, and the regeneration temperature is 80-120°C.

[0015] Preferably, the anode raw material is a [bmim]Cl solution, the cathode raw material is a bistrifluoromethanesulfonyl imide solution, the molar ratio of [bmim]Cl to bistrifluoromethanesulfonyl imide in the added anode raw material and cathode raw material is 2:3, and the ionic liquid formed by electrolysis is 1-butyl-3-methylimidazolium bistrifluoromethanesulfonyl imide salt;

[0016] The chain alcohol amine is ethanolamine, and the mass ratio of the added ethanolamine to the ionic liquid is 3:1.

[0017] Preferably, the anode raw material is a [bmim]Cl solution, the cathode raw material is a hexafluorophosphoric acid solution, the molar ratio of [bmim]Cl to hexafluorophosphoric acid in the added anode raw material and cathode raw material is 2.5:3, and the ionic liquid formed by electrolysis is 1-butyl-3-methylimidazolium hexafluorophosphate;

[0018] The chain alcohol amine is diethanolamine, and the mass ratio of the added diethanolamine to the ionic liquid is 2:1.

[0019] Preferably, the anode raw material is [emim]Cl solution, the cathode raw material is tetrafluoroboric acid solution, the molar ratio of [emim]Cl to tetrafluoroboric acid in the added anode raw material and cathode raw material is 1:1, and the ionic liquid formed by electrolysis is 1-ethyl-3-methylimidazolium tetrafluoroborate;

[0020] The chain alcohol amine is ethanolamine, and the mass ratio of the added ethanolamine to the ionic liquid is 3:1.

[0021] In a second aspect of the present invention, there is provided a system for preparing ionic liquid by electrochemical method and compounding with chain alcohol amine to absorb carbon dioxide, which uses the above method to treat waste gas containing carbon dioxide, and the system comprises:

[0022] An exhaust gas pretreatment device, comprising a spray tower and a dust removal device connected to the spray tower;

[0023] A carbon dioxide absorption tower, wherein the bottom is provided with an air inlet connected to the dust removal device, the upper side is provided with a liquid inlet for the ionic liquid-alkanolamine composite absorbent to enter, the bottom side is provided with a regeneration liquid discharge port for discharging the ionic liquid-alkanolamine composite absorbent remaining in the tower, and the regeneration liquid discharge port is provided with a filter screen;

[0024] An absorbent preparation device, comprising a three-chamber electrolytic cell for electrolytically preparing an ionic liquid and a liquid inlet pipe for conveying a chain alcohol amine solution into the three-chamber electrolytic cell, wherein the upper portion of the three-chamber electrolytic cell is connected to the liquid inlet of the carbon dioxide absorption tower through the absorbent conveying pipe;

[0025] And an absorbent regeneration device, which includes a regeneration kettle connected to the regeneration liquid discharge port of the spray tower and a regeneration absorbent delivery pipe connected to the regeneration kettle and the liquid inlet pipe.

[0026] Preferably, the three-chamber electrolytic cell is provided with an anode chamber, a middle chamber and a cathode chamber in sequence, the anode chamber is provided with an anode and a cation exchange membrane in sequence from the outside to the inside, the cathode chamber is provided with a cathode and an anion exchange membrane in sequence from the outside to the inside, the middle chamber is provided with a compounding chamber, the compounding chamber is provided with a plurality of one-way liquid inlets, the one-way liquid inlet is provided with a one-way valve that only allows the ionic liquid in the middle chamber to enter the compounding chamber in one direction, and the bottom of the compounding chamber is connected to the liquid inlet pipe.

[0027] Preferably, the first side of the three-chamber electrolytic cell is connected to an anode raw material delivery pipe, and the anode raw material delivery pipe is provided with an anode raw material delivery pump;

[0028] The second side of the three-chamber electrolytic cell is connected to a cathode raw material delivery pipe, and a cathode raw material delivery pump is provided on the cathode raw material delivery pipe;

[0029] The liquid inlet pipe is provided with a liquid inlet delivery pump, and the absorbent delivery pipe is provided with an absorbent delivery pump.

[0030] The regenerative absorbent delivery pipe is provided with a regenerative absorbent delivery pump.

[0031] Preferably, the anode raw material enters the anode chamber through the anode raw material delivery pipe, the target cation reaches the middle compartment after passing through the cation exchange membrane, the cathode raw material enters the cathode chamber through the cathode raw material delivery pipe, the target anion reaches the middle compartment after passing through the anion exchange membrane, and the ionic liquid generated by the reaction of the target cation and the target anion in the middle compartment flows into the compounding chamber through the one-way liquid inlet, and is mixed with the chain alcohol amine solution input into the compounding chamber through the liquid inlet pipe to form an ionic liquid-chain alcohol amine composite absorbent, which is then transported to the liquid inlet of the carbon dioxide absorption tower through the absorbent delivery pipe;

[0032] The waste gas to be treated passes through the spray tower and the dust removal device in sequence and then enters the air inlet of the carbon dioxide absorption tower, where it is absorbed by the ionic liquid-alkanolamine composite absorbent inside to form solid urethane products; the ionic liquid-alkanolamine composite absorbent remaining in the carbon dioxide absorption tower is separated from the solid urethane products by the filter screen on the regeneration discharge port and then transported to the regeneration kettle; the regenerated ionic liquid-alkanolamine composite absorbent obtained in the regeneration kettle is transported to the liquid inlet pipe through the regeneration absorbent transport pipe, enters the compounding chamber together with the alkanolamine solution, and finally re-enters the carbon dioxide absorption tower.

[0033] The beneficial effects of the present invention are:

[0034] The present invention provides an ionic liquid-chain alcohol amine composite absorbent as a CO2 treatment material, which has good absorption capacity and fast absorption rate, reduces the viscosity of the system, can avoid equipment corrosion to a certain extent, increase the CO2 load capacity limited by corrosion / degradation; reduce the regeneration temperature; and reduce the regeneration volume and regeneration energy by separating the CO2 capture product.

[0035] The present invention further provides a system for absorbing carbon dioxide based on the ionic liquid-alkanolamine composite absorbent. The system has a simple overall structure and can realize the online preparation and supply of the ionic liquid-alkanolamine composite absorbent. At the same time, the absorbent can be regenerated at a relatively low temperature, which can effectively reduce the regeneration energy consumption and the consumption of the absorbent. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a schematic diagram of the structure of a system for preparing an ionic liquid and a chain alcohol amine for absorbing carbon dioxide by an electrochemical method in Example 1.

[0037] Description of reference numerals:

[0038] 1—waste gas pretreatment device; 11—spray tower; 12—dust removal device;

[0039] 2—Carbon dioxide absorption tower; 21—air inlet; 22—liquid inlet; 23—regeneration liquid outlet;

[0040] 3—absorbent preparation device; 31—liquid inlet pipe; 32—three-chamber electrolytic cell; 33—liquid inlet delivery pump; 34-absorbent delivery pipe; 35—absorbent delivery pump; 36—anode raw material delivery pipe; 37—anode raw material delivery pump; 38—cathode raw material delivery pipe; 39—cathode raw material delivery pump; 321—anode chamber; 322—anode, 323—cation exchange membrane, 324—middle compartment, 325—cathode chamber, 326—cathode, 327—anion exchange membrane, 328—compounding chamber, 329—one-way liquid inlet;

[0041] 4—absorbent regeneration device; 41—regeneration kettle; 42—regeneration absorbent delivery pipe 34; 43—regeneration absorbent delivery pump 35. DETAILED DESCRIPTION

[0042] The present invention is further described in detail below in conjunction with embodiments so that those skilled in the art can implement the invention with reference to the description.

[0043] It should be understood that the terms such as “having”, “including” and “comprising” used herein do not exclude the existence or addition of one or more other elements or combinations thereof.

[0044] The test methods used in the following examples are conventional methods unless otherwise specified. The materials and reagents used in the following examples are all commercially available unless otherwise specified. In the following examples, if no specific conditions are specified, the experiments were carried out under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used, if the manufacturer is not specified, are all conventional products that can be purchased commercially.

[0045] The present invention provides a method for preparing an ionic liquid and a chain alcohol amine by an electrochemical method for absorbing carbon dioxide, comprising the following steps:

[0046] S1, transporting the waste gas containing carbon dioxide to be treated to the carbon dioxide absorption tower 2 after pretreatment;

[0047] S2. Preparation of ionic liquid-alkanolamine composite absorbent:

[0048] The anode raw material containing the target cation is put into the anode 322 of the electrolytic cell, and the cathode raw material containing the target anion is put into the cathode 326 of the electrolytic cell. The target cation passes through the cation exchange membrane 323 and the target anion passes through the anion exchange membrane 327 to form an ionic liquid under electrolysis. The ionic liquid is then mixed with the introduced chain alcohol amine solution to obtain a liquid ionic liquid-chain alcohol amine composite absorbent for absorbing carbon dioxide;

[0049] S3, passing the ionic liquid-alkanolamine composite absorbent into the carbon dioxide absorption tower 2 to absorb the carbon dioxide;

[0050] S4, the ionic liquid-alkanolamine composite absorbent in the carbon dioxide absorption tower 2 forms a solid urethane product with carbon dioxide, and the residual ionic liquid-alkanolamine composite absorbent in the carbon dioxide absorption tower 2 is separated from the solid urethane product and then output for regeneration, and then mixed with the new ionic liquid-alkanolamine composite absorbent prepared in step S2 and re-enters the carbon dioxide absorption tower 2.

[0051] In a preferred embodiment, the pretreatment method of the waste gas to be treated is: the waste gas to be treated is first sprayed through a spray tower 11, and then dusted. The spray tower 11 can use a conventional spray liquid for waste gas treatment, which is not specifically limited in the present invention.

[0052] Preferably, the residual ionic liquid-alkanolamine composite absorbent in step S4 is transported to the absorbent regeneration device 4 for heating to achieve regeneration, and the regeneration temperature is 80-120° C., more preferably 100° C. The absorbent regeneration device 4 mainly provides a heating function, and a conventional container capable of providing this function can be used, such as a regeneration kettle 41 with a heating function.

[0053] Preferably, the anode raw material is a [bmim]Cl solution, the cathode raw material is a bistrifluoromethanesulfonyl imide solution, the molar ratio of [bmim]Cl to bistrifluoromethanesulfonyl imide in the added anode raw material and cathode raw material is 2:3, and the ionic liquid formed by electrolysis is 1-butyl-3-methylimidazolium bistrifluoromethanesulfonyl imide salt;

[0054] The chain alcohol amine is ethanolamine, and the mass ratio of the added ethanolamine to the ionic liquid is 3:1.

[0055] Preferably, the anode raw material is a [bmim]Cl solution, the cathode raw material is a hexafluorophosphoric acid solution, the molar ratio of [bmim]Cl to hexafluorophosphoric acid in the added anode raw material and cathode raw material is 2.5:3, and the ionic liquid formed by electrolysis is 1-butyl-3-methylimidazolium hexafluorophosphate;

[0056] The chain alcohol amine is diethanolamine, and the mass ratio of the added diethanolamine to the ionic liquid is 2:1.

[0057] Preferably, the anode raw material is [emim]Cl solution, the cathode raw material is tetrafluoroboric acid solution, the molar ratio of [emim]Cl to tetrafluoroboric acid in the added anode raw material and cathode raw material is 1:1, and the ionic liquid formed by electrolysis is 1-ethyl-3-methylimidazolium tetrafluoroborate;

[0058] The chain alcohol amine is ethanolamine, and the mass ratio of the added ethanolamine to the ionic liquid is 3:1.

[0059] In a second aspect of the present invention, a system for preparing ionic liquid and chain alcohol amine by electrochemical method to absorb carbon dioxide is provided, which uses the above method to treat waste gas containing carbon dioxide, and the system comprises:

[0060] An exhaust gas pretreatment device 1, comprising a spray tower 11 and a dust removal device 12 connected to the spray tower 11;

[0061] The carbon dioxide absorption tower 2 has an air inlet 21 connected to the dust removal device 12 at the bottom, a liquid inlet 22 for the ionic liquid-alkanolamine composite absorbent to enter the upper side, and a regeneration liquid discharge port 23 for discharging the ionic liquid-alkanolamine composite absorbent remaining in the tower at the bottom side, and a filter screen is arranged on the regeneration liquid discharge port 23;

[0062] An absorbent preparation device 3, which includes a three-chamber electrolytic cell 32 for electrolytically preparing an ionic liquid and a liquid inlet pipe 31 for conveying a chain alcohol amine solution into the three-chamber electrolytic cell 32, wherein the upper portion of the three-chamber electrolytic cell 32 is connected to the liquid inlet 22 of the carbon dioxide absorption tower 2 through an absorbent delivery pipe 34;

[0063] And an absorbent regeneration device 4, which includes a regeneration tank 41 connected to the regeneration liquid discharge port 23 of the spray tower 11 and a regeneration absorbent delivery pipe 42 connecting the regeneration tank 41 to the liquid inlet pipe 31.

[0064] Preferably, the three-chamber electrolytic cell 32 is provided with an anode chamber 322, a middle chamber 324 and a cathode chamber 325 in sequence, the anode chamber 321 is provided with an anode 322 and a cation exchange membrane 323 in sequence from the outside to the inside, the cathode chamber 325 is provided with a cathode 326 and an anion exchange membrane 327 in sequence from the outside to the inside, the middle chamber 324 is provided with a compounding chamber 328, the compounding chamber 328 is provided with a plurality of one-way liquid inlets 329, the one-way liquid inlet 329 is provided with a one-way valve that only allows the ionic liquid in the middle chamber 324 to enter the compounding chamber 328 in one direction, and the bottom of the compounding chamber 328 is connected to the liquid inlet pipe 31.

[0065] Preferably, the first side of the three-chamber electrolytic cell 32 is connected to an anode raw material delivery pipe 36, and an anode raw material delivery pump 37 is provided on the anode raw material delivery pipe 36;

[0066] A cathode raw material delivery pipe 38 is connected to the second side of the three-chamber electrolytic cell 32, and a cathode raw material delivery pump 39 is provided on the cathode raw material delivery pipe 38;

[0067] The liquid inlet pipe 31 is provided with a liquid inlet delivery pump 33 , and the absorbent delivery pipe 34 is provided with an absorbent delivery pump 35 .

[0068] The regenerated absorbent delivery pipe 42 is provided with a regenerated absorbent delivery pump 43 .

[0069] Preferably, the anode raw material enters the anode chamber 321 through the anode raw material delivery pipe 36, and the target cations reach the middle compartment 324 after passing through the cation exchange membrane 323, and the cations therein can be reduced by electrolysis; the cathode raw material enters the cathode chamber 325 through the cathode raw material delivery pipe 38, and the target anions reach the middle compartment 324 after passing through the anion exchange membrane 327, and the anions therein can be oxidized by electrolysis; the ionic liquid (the gas formed by electrolysis is discharged) generated by the reaction of the target cations and the target anions in the middle compartment 324 flows into the compounding chamber 328 through the one-way liquid inlet 329, and is mixed with the chain alcohol amine solution input into the compounding chamber 328 through the liquid inlet pipe 31 to form an ionic liquid-chain alcohol amine composite absorbent, and then is transported to the liquid inlet 22 of the carbon dioxide absorption tower 2 through the absorbent delivery pipe 34; in the electrolytic cell, the raw materials can be flexibly adjusted as needed to prepare different ionic liquids, and a variety of carbon dioxide absorbents can also be obtained with different chain alcohol amine solutions and compounding ratios.

[0070] The waste gas to be treated passes through the spray tower 11 (to remove gases such as SO2, H2S, etc.) and the dust removal device 12 (to remove particulate matter in the gas) in turn and then enters the air inlet 21 of the carbon dioxide absorption tower 2, where it is absorbed by the ionic liquid-chain alcohol amine composite absorbent inside to form a solid urethane product; the ionic liquid-chain alcohol amine composite absorbent remaining in the carbon dioxide absorption tower 2 is separated from the solid urethane product by the filter screen on the regeneration discharge port 23 and then transported to the regeneration kettle 41; the regenerated ionic liquid-chain alcohol amine composite absorbent obtained in the regeneration kettle 41 is transported to the liquid inlet pipe 31 via the regeneration absorbent transport pipe 42, and enters the compounding chamber 328 together with the chain alcohol amine solution, and finally re-enters the carbon dioxide absorption tower 2.

[0071] The present invention provides an ionic liquid-alkanolamine composite absorbent as a CO2 treatment material. Replacing the aqueous phase with a more stable ionic liquid can avoid corrosion and equilibrium limitation problems. More importantly, the presence of the ionic liquid provides a favorable environment for the crystallization of the CO2 capture product, thereby easily separating the solid urethane (CO2 capture product) from the liquid counterpart in addition to completing the reaction to its full stoichiometric potential. Since the solubility of CO2 in imidazole ionic liquids is about 3 times that in water, the new method of absorbing CO2 in an alkanolamine-imidazole ionic liquid mixture can ensure a larger mass transfer capacity, thereby compensating to a certain extent for the disadvantages caused by the higher viscosity of the ionic liquid.

[0072] The improved ionic liquid-chain alcohol amine composite absorbent of the present invention has good absorption capacity and fast absorption rate, reduces the viscosity of the system, can avoid equipment corrosion to a certain extent, increase the CO2 load capacity limited by corrosion / degradation; reduce the regeneration temperature; reduce the regeneration volume by separating the CO2 capture product, and reduce the regeneration energy.

[0073] The present invention further provides a system for absorbing carbon dioxide based on the ionic liquid-alkanolamine composite absorbent. The system has a simple overall structure and can realize the online preparation and supply of the ionic liquid-alkanolamine composite absorbent. At the same time, the absorbent can be regenerated at a relatively low temperature, which can effectively reduce the regeneration energy consumption and the consumption of the absorbent.

[0074] The above is the overall concept of the present invention, and detailed embodiments and comparative examples are provided below on the basis of the overall concept of the present invention to further illustrate the present invention.

[0075] Example 1

[0076] A system for preparing ionic liquid and chain alcohol amine by electrochemical method to absorb carbon dioxide, which uses the above method to treat waste gas containing carbon dioxide, and the system includes:

[0077] An exhaust gas pretreatment device 1, comprising a spray tower 11 and a dust removal device 12 connected to the spray tower 11;

[0078] The carbon dioxide absorption tower 2 has an air inlet 21 connected to the dust removal device 12 at the bottom, a liquid inlet 22 for the ionic liquid-alkanolamine composite absorbent to enter the upper side, and a regeneration liquid discharge port 23 for discharging the ionic liquid-alkanolamine composite absorbent remaining in the tower at the bottom side, and a filter screen (not shown in the figure) is arranged on the regeneration liquid discharge port 23;

[0079] An absorbent preparation device 3, which includes a three-chamber electrolytic cell 32 for electrolytically preparing an ionic liquid and a liquid inlet pipe 31 for conveying a chain alcohol amine solution into the three-chamber electrolytic cell 32, wherein the upper portion of the three-chamber electrolytic cell 32 is connected to the liquid inlet 22 of the carbon dioxide absorption tower 2 through an absorbent delivery pipe 34;

[0080] And an absorbent regeneration device 4, which includes a regeneration tank 41 connected to the regeneration liquid discharge port 23 of the spray tower 11 and a regeneration absorbent delivery pipe 42 connecting the regeneration tank 41 to the liquid inlet pipe 31.

[0081] In this embodiment, the spray tower 11 specifically uses a 30 wt % sodium hydroxide solution for spraying.

[0082] In this embodiment, the three-chamber electrolytic cell 32 is provided with an anode chamber 321, a middle compartment 324 and a cathode chamber 325 in sequence. The anode chamber 321 is provided with an anode 322 and a cation exchange membrane 323 in sequence from the outside to the inside. The cathode chamber 325 is provided with a cathode 326 and an anion exchange membrane 327 in sequence from the outside to the inside. The middle compartment 324 is provided with a compounding chamber 328. The compounding chamber 328 is provided with a plurality of one-way liquid inlets 329. The one-way liquid inlet 329 is provided with a one-way valve (not shown in the figure) that only allows the ionic liquid in the middle compartment 324 to enter the compounding chamber 328 in one direction. The bottom of the compounding chamber 328 is connected to the liquid inlet pipe 31.

[0083] In this embodiment, the first side of the three-chamber electrolytic cell 32 is connected to an anode raw material delivery pipe 36, and an anode raw material delivery pump 37 is provided on the anode raw material delivery pipe 36;

[0084] A cathode raw material delivery pipe 38 is connected to the second side of the three-chamber electrolytic cell 32, and a cathode raw material delivery pump 39 is provided on the cathode raw material delivery pipe 38;

[0085] The liquid inlet pipe 31 is provided with a liquid inlet delivery pump 33 , and the absorbent delivery pipe 34 is provided with an absorbent delivery pump 35 .

[0086] The regenerated absorbent delivery pipe 42 is provided with a regenerated absorbent delivery pump 43 .

[0087] In this embodiment, the working process of the system is as follows:

[0088] The anode raw material enters the anode chamber 321 through the anode raw material delivery pipe 36, and the target cations pass through the cation exchange membrane 323 and reach the middle compartment 324, where the cations can be reduced by electrolysis; the cathode raw material enters the cathode chamber 325 through the cathode raw material delivery pipe 38, and the target anions pass through the anion exchange membrane 327 and reach the middle compartment 324, where the anions can be oxidized by electrolysis; the ionic liquid (the gas formed by electrolysis is discharged) generated by the reaction of the target cations and the target anions in the middle compartment 324 flows into the compounding chamber 328 through the one-way liquid inlet 329, and is mixed with the chain alcohol amine solution input into the compounding chamber 328 through the liquid inlet pipe 31 to form an ionic liquid-chain alcohol amine composite absorbent, and then is transported to the liquid inlet 22 of the carbon dioxide absorption tower 2 through the absorbent delivery pipe 34;

[0089] The waste gas to be treated passes through the spray tower 11 (to remove gases such as SO2, H2S, etc.) and the dust removal device 12 (to remove particulate matter in the gas) in turn and then enters the air inlet 21 of the carbon dioxide absorption tower 2, where it is reversely contacted with the ionic liquid-chain alcohol amine composite absorbent inside and is absorbed to form a solid urethane product; the ionic liquid-chain alcohol amine composite absorbent remaining in the carbon dioxide absorption tower 2 is separated from the solid urethane product by the filter screen on the regeneration discharge port 23 and then transported to the regeneration kettle 41. The regenerated ionic liquid-chain alcohol amine composite absorbent obtained by heating at a temperature of 100°C in the regeneration kettle 41 is transported to the liquid inlet pipe 31 through the regeneration absorbent transport pipe 42, and enters the compounding chamber 328 together with the chain alcohol amine solution, and finally re-enters the carbon dioxide absorption tower 2.

[0090] In this embodiment, the raw materials added to the three-chamber electrolytic cell 32 are as follows:

[0091] A 2 mol / L [bmim]Cl (1-butyl-3-methylimidazolium chloride) solution is added to the anode chamber 321, and a [bmim]Cl solution is continuously added to the anode chamber 321 during the electrolysis process to maintain a concentration of 2 mol / L in the compartment during electrolysis, and a 3 mol / L bistrifluoromethanesulfonyl imide solution is added to the cathode chamber 325. The battery is powered until the pH of the solution in the middle compartment 324 rises to 7.0, and then the electrolysis is stopped. The ionic liquid product: [bmim][Tf2N] (1-butyl-3-methylimidazolium bistrifluoromethanesulfonyl imide salt) is obtained at a yield of 59%. MEA is added to the compounding chamber 328 at a mass ratio of 30 wt% MEA (ethanolamine) and 10 wt% [bmim][Tf2N], and the resulting mixed solution is an ionic liquid-chain alcohol amine composite absorbent.

[0092] In this embodiment, in the carbon dioxide absorption tower 2, waste gas treatment of a steel plant is carried out at 40°C. The waste gas components are mainly about 26wt% of particulate matter, about 10wt% of sulfur dioxide, about 21wt% of carbon oxides (CO, CO2), about 17wt% of nitrogen oxides, about 12wt% of hydrogen sulfide, and the rest are nitrogen, oxygen and other components. The main indicators are as follows: 1g of ionic liquid-chain alcohol amine composite absorbent absorbs 0.23g of CO2, and the viscosity of the solvent before and after absorbing CO2 is 3.17mPa·s and 4.82mPa·s respectively. In the regeneration kettle 41, the absorbent is regenerated at 100°C, the regeneration energy consumption is 45.69kJ / mol, and the regeneration efficiency is 87.43%.

[0093] Example 2

[0094] This example is basically the same as Example 1, and the main differences are listed below.

[0095] In this embodiment, the raw materials added to the three-chamber electrolytic cell 32 are as follows:

[0096] A 2.5 mol / L [bmim]Cl (1-butyl-3-methylimidazolium chloride) solution is added to the anode chamber 321, and a [bmim]Cl solution is continuously added to the anode chamber 321 during the electrolysis process to maintain a concentration of 2.5 mol / L in the compartment during electrolysis, and a 3 mol / L hexafluorophosphoric acid solution is added to the cathode chamber 325. The battery is powered until the pH of the solution in the middle compartment 324 rises to 7.0, and then the electrolysis is stopped. The ionic liquid product: [bmim][PF6] (1-butyl-3-methylimidazolium hexafluorophosphate) is obtained at a yield of 63%. DEA is added to the compounding chamber 328 at a mass ratio of 20 wt% DEA (diethanolamine) and 10 wt% [bmim][PF6], and the resulting mixed solution is an ionic liquid-chain alcohol amine composite absorbent.

[0097] In this embodiment, waste gas treatment is carried out at 40°C in the carbon dioxide absorption tower 2 (the waste gas source is the same as in Example 1), and the main indicators are as follows: 1g of the composite system absorbs 0.16g of CO2, and the viscosity of the solvent before and after absorbing CO2 is 3.57 and 5.14mPa·s respectively. In the regeneration kettle 41, the absorbent is regenerated at 100°C, the regeneration energy consumption is 63.31kJ / mol, and the regeneration efficiency is 84.76%.

[0098] Example 3

[0099] This example is basically the same as Example 1, and the main differences are listed below.

[0100] In this embodiment, the raw materials added to the three-chamber electrolytic cell 32 are as follows:

[0101] A 3 mol / L [emim]Cl (1-ethyl-3-methylimidazolium chloride) solution is added to the anode chamber 321, and the [emim]Cl solution is continuously added to the anode chamber 321 during the electrolysis process to maintain a concentration of 3 mol / L in the compartment during the electrolysis, and a 3 mol / L tetrafluoroboric acid solution is added to the cathode chamber 325. The battery is powered until the pH of the solution in the middle compartment 324 rises to 7.0, and then the electrolysis is stopped. The ionic liquid product: [emim][BF6] (1-ethyl-3-methylimidazolium tetrafluoroborate) is obtained at a yield of 72%. DEA is added to the compounding chamber 328 at a mass ratio of 30 wt% MEA and 10 wt% [emim][BF6], and the resulting mixed solution is an ionic liquid-chain alcohol amine composite absorbent.

[0102] In this embodiment, waste gas treatment is carried out at 40°C in the carbon dioxide absorption tower 2 (the waste gas source is the same as in Example 1), and the main indicators are as follows: 1g of ionic liquid-chain alcohol amine composite absorbent absorbs 0.23g of CO2, and the viscosity of the solvent before and after absorbing CO2 is 3.13 and 4.57mPa·s respectively. In the regeneration kettle 41, the absorbent is regenerated at 100°C, the regeneration energy consumption is 56.38kJ / mol, and the regeneration efficiency is 91.27%.

[0103] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and the implementation modes. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to specific details.

Claims

1. A method for preparing ionic liquid and chain alcohol amine by electrochemical method to absorb carbon dioxide, characterized in that: The following steps are involved: S1, transporting the waste gas containing carbon dioxide to be treated to a carbon dioxide absorption tower after pretreatment; S2. Preparation of ionic liquid-alkanolamine composite absorbent: The anode raw material containing the target cation is put into the anode of the electrolytic cell, and the cathode raw material containing the target anion is put into the cathode of the electrolytic cell. The target cation passes through the cation exchange membrane and forms an ionic liquid with the target anion passing through the anion exchange membrane under electrolysis. The ionic liquid is then mixed with the introduced chain alcohol amine solution to obtain a liquid ionic liquid-chain alcohol amine composite absorbent for absorbing carbon dioxide; S3, passing the ionic liquid-alkanolamine composite absorbent into a carbon dioxide absorption tower to absorb the carbon dioxide; S4, the ionic liquid-alkanolamine composite absorbent in the carbon dioxide absorption tower forms a solid urethane product with carbon dioxide, and the residual ionic liquid-alkanolamine composite absorbent in the carbon dioxide absorption tower is separated from the solid urethane product and then output for regeneration, and then mixed with the new ionic liquid-alkanolamine composite absorbent prepared in step S2 and re-enters the carbon dioxide absorption tower.

2. The method for preparing ionic liquid and chain alcohol amine by electrochemical method for absorbing carbon dioxide according to claim 1, characterized in that: The pretreatment method of the waste gas to be treated is: the waste gas to be treated is first sprayed through a spray tower, and then dusted.

3. The method for preparing ionic liquid and chain alcohol amine by electrochemical method for absorbing carbon dioxide according to claim 2, characterized in that: The residual ionic liquid-alkanolamine composite absorbent in step S4 is transported to an absorbent regeneration device for heating to achieve regeneration, and the regeneration temperature is 80-120°C.

4. The method for preparing ionic liquid and chain alcohol amine by electrochemical method for absorbing carbon dioxide according to claim 3, characterized in that: The anode raw material is a [bmim]Cl solution, the cathode raw material is a bistrifluoromethanesulfonyl imide solution, the molar ratio of [bmim]Cl to bistrifluoromethanesulfonyl imide in the added anode raw material and cathode raw material is 2:3, and the ionic liquid formed by electrolysis is 1-butyl-3-methylimidazolium bistrifluoromethanesulfonyl imide salt; The chain alcohol amine is ethanolamine, and the mass ratio of the added ethanolamine to the ionic liquid is 3:

1.

5. The method for preparing ionic liquid and chain alcohol amine by electrochemical method for absorbing carbon dioxide according to claim 3, characterized in that: The anode raw material is a [bmim]Cl solution, the cathode raw material is a hexafluorophosphoric acid solution, the molar ratio of [bmim]Cl to hexafluorophosphoric acid in the added anode raw material and cathode raw material is 2.5:3, and the ionic liquid formed by electrolysis is 1-butyl-3-methylimidazolium hexafluorophosphate; The chain alcohol amine is diethanolamine, and the mass ratio of the added diethanolamine to the ionic liquid is 2:

1.

6. The method for preparing ionic liquid and chain alcohol amine by electrochemical method for absorbing carbon dioxide according to claim 3, characterized in that: The anode raw material is [emim]Cl solution, the cathode raw material is tetrafluoroboric acid solution, the molar ratio of [emim]Cl to tetrafluoroboric acid in the added anode raw material and cathode raw material is 1:1, and the ionic liquid formed by electrolysis is 1-ethyl-3-methylimidazolium tetrafluoroborate; The chain alcohol amine is ethanolamine, and the mass ratio of the added ethanolamine to the ionic liquid is 3:

1.

7. A system for preparing ionic liquid and chain alcohol amine by electrochemical method to absorb carbon dioxide, characterized in that: The method according to any one of claims 1 to 6 is used to treat waste gas containing carbon dioxide, and the system comprises: An exhaust gas pretreatment device, comprising a spray tower and a dust removal device connected to the spray tower; A carbon dioxide absorption tower, wherein the bottom is provided with an air inlet connected to the dust removal device, the upper side is provided with a liquid inlet for the ionic liquid-alkanolamine composite absorbent to enter, the bottom side is provided with a regeneration liquid discharge port for discharging the ionic liquid-alkanolamine composite absorbent remaining in the tower, and the regeneration liquid discharge port is provided with a filter screen; An absorbent preparation device, comprising a three-chamber electrolytic cell for electrolytically preparing an ionic liquid and a liquid inlet pipe for conveying a chain alcohol amine solution into the three-chamber electrolytic cell, wherein the upper portion of the three-chamber electrolytic cell is connected to the liquid inlet of the carbon dioxide absorption tower through the absorbent conveying pipe; And an absorbent regeneration device, which includes a regeneration kettle connected to the regeneration liquid discharge port of the spray tower and a regeneration absorbent delivery pipe connected to the regeneration kettle and the liquid inlet pipe.

8. The system for preparing ionic liquid and chain alcohol amine for absorbing carbon dioxide by electrochemical method according to claim 7, characterized in that: The three-chamber electrolytic cell is provided with an anode chamber, a middle chamber and a cathode chamber in sequence. The anode chamber is provided with an anode and a cation exchange membrane in sequence from the outside to the inside. The cathode chamber is provided with a cathode and an anion exchange membrane in sequence from the outside to the inside. The middle chamber is provided with a compounding chamber. The compounding chamber is provided with a plurality of one-way liquid inlets. The one-way liquid inlet is provided with a one-way valve that only allows the ionic liquid in the middle chamber to enter the compounding chamber in one direction. The bottom of the compounding chamber is connected with the liquid inlet pipe.

9. The system for preparing ionic liquid and chain alcohol amine for absorbing carbon dioxide by electrochemical method according to claim 8, characterized in that: The first side of the three-chamber electrolytic cell is connected to an anode raw material delivery pipe, and the anode raw material delivery pipe is provided with an anode raw material delivery pump; The second side of the three-chamber electrolytic cell is connected to a cathode raw material delivery pipe, and a cathode raw material delivery pump is provided on the cathode raw material delivery pipe; The liquid inlet pipe is provided with a liquid inlet delivery pump, and the absorbent delivery pipe is provided with an absorbent delivery pump; The regenerative absorbent delivery pipe is provided with a regenerative absorbent delivery pump.

10. The system for preparing ionic liquid and chain alcohol amine for absorbing carbon dioxide by electrochemical method according to claim 9, characterized in that: The anode raw material enters the anode chamber through the anode raw material delivery pipe, the target cation passes through the cation exchange membrane and reaches the middle compartment, the cathode raw material enters the cathode chamber through the cathode raw material delivery pipe, the target anion passes through the anion exchange membrane and reaches the middle compartment, the ionic liquid generated by the reaction of the target cation and the target anion in the middle compartment flows into the compounding chamber through the one-way liquid inlet, and is mixed with the chain alcohol amine solution input into the compounding chamber through the liquid inlet pipe to form an ionic liquid-chain alcohol amine composite absorbent, which is then transported to the liquid inlet of the carbon dioxide absorption tower through the absorbent delivery pipe; The waste gas to be treated passes through the spray tower and the dust removal device in sequence and then enters the air inlet of the carbon dioxide absorption tower, where it is absorbed by the ionic liquid-alkanolamine composite absorbent inside to form solid urethane products; the ionic liquid-alkanolamine composite absorbent remaining in the carbon dioxide absorption tower is separated from the solid urethane products by the filter screen on the regeneration discharge port and then transported to the regeneration kettle; the regenerated ionic liquid-alkanolamine composite absorbent obtained in the regeneration kettle is transported to the liquid inlet pipe through the regeneration absorbent transport pipe, enters the compounding chamber together with the alkanolamine solution, and finally re-enters the carbon dioxide absorption tower.

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