Phase change absorbent and integrated trapping method for desulfurization and decarburization of flue gas

Abstract

The invention provides a phase change absorbent and an integrated trapping method for desulfurization and decarburization of flue gas, the flue gas containing CO2 and SO2 is treated based on the phase change absorbent, and particularly, the flue gas is treated by adopting the integrated trapping method disclosed by the invention, so that CO2 and SO2 can be synchronously absorbed, and selective regeneration is realized. The phase change absorbent is an aqueous solution containing 5-80 wt% of organic amine and 5-80 wt% of ionic liquid; the ionic liquid comprises anions and cations; the positive ions are selected from one or more of imidazole positive ions, pyrrolidine positive ions, quaternary amine positive ions, pyridine positive ions, piperidine positive ions, piperazine positive ions and pyrrole positive ions; the anions are selected from one or more of hydrophobic fluorine-containing anions, hydrophobic sulfonate-containing anions and hydrophobic fatty acid anions.

Description

TECHNICAL FIELD

[0001] The present application relates to a flue gas desulfurization and decarburization technology, in particular to a phase change type absorbent and an integrated capture method for flue gas desulfurization and decarburization. BACKGROUND

[0002] CO2 as a greenhouse gas, excessive emission will cause global warming problem; and the emission of SO2 will cause harm to human body, and also form acid rain with water, causing soil acidification. CN113244761B reports a solvent composed of an absorbent and an organosilicon for capturing CO2, SO2, H2S and other acid gases in flue gas, and the absorption product can be desorbed by high temperature or chemical reaction, realizing the reduction of desorption energy consumption, and the recycling of the absorbent and the solvent. The solvent in the scheme is separated into two phases, the organosilicon solvent as a phase in the upper layer, and has no function of absorbing any one of CO2, SO2 and H2S gas, and for the mixed gas of two or three of CO2, SO2 and H2S, only the absorbent phase can be enriched, and the selective regeneration cannot be realized. SUMMARY

[0003] The present application provides a phase change type absorbent and an integrated capture method for flue gas desulfurization and decarburization, based on the phase change type absorbent of the present application, the flue gas containing CO2 and SO2 is treated, especially using the integrated capture method of the present application to treat the flue gas, CO2 and SO2 can be absorbed synchronously, and CO2 and SO2 can be well separated in the desorption process, realizing selective regeneration.

[0004] To achieve the purpose of the present application, the following technical solutions are provided:

[0005] The present application provides a phase change type absorbent for flue gas desulfurization and decarburization, the phase change type absorbent is an aqueous solution containing 5-80wt% of an organic amine and 5-80wt% of an ionic liquid;

[0006] The ionic liquid includes anions and cations;

[0007] The cation is selected from one or more of imidazole cation, pyrrolidine cation, quaternary amine cation, pyridine cation, piperidine cation, piperazine cation and pyrrole cation;

[0008] The anion is selected from one or more of hydrophobic fluorine-containing anion, hydrophobic sulfonate-containing anion and hydrophobic fatty acid anion.

[0009] Further, the cation in the ionic liquid is selected from one or more of the cations having the following structural formula (II)-(VIII):

[0010] Further, the cation in the ionic liquid is selected from one or more of the cations having the following structural formula (II)-(VIII):

[0012] R1-R8 in the structural formulae (II)-(VIII) are each independently selected from H, hydroxyl or C1-C8 alkyl; optionally, some of the groups R1-R8 form a ring; preferably, the C1-C8 alkyl contains a hydroxyl and / or amine substituent. 48 each independently H or C1-C8 alkyl; preferably, the C1-C8 alkyl contains an ether group, a hydroxyl group, a nitrile group and / or an amine group.

[0013] Preferably, the cation carries a C1-C8 alkyl group containing an ether group, a hydroxyl group, a nitrile group and / or an amine group.

[0014] Preferably, the cation in the ionic liquid is selected from pyridinium cations.

[0015] Preferably, the anion in the ionic liquid is selected from one or more of BF4 - , PF6 - , CH3(CH2) p COO - , C8H 17 SO4 - , C4F9SO3 - , CF3SO3 - , CF3(CF2) q SO3 - , (CF3SO2)3C - , (C2F5SO2)2N - , (CF3SO2)2N - , CH3CH(OH)COO - , dodecylsulfonate, benzenesulfonate and p-toluenesulfonate, wherein p, q are each independently an integer from 0 to 12.

[0016] Further, the organic amine is selected from one or more of the compounds having the following structural formula (I):

[0017]

[0018] R1-R5 in the structural formula (I) are each independently selected from H, hydroxyl or C1-C8 alkyl; optionally, some of the groups R1-R5 form a ring; preferably, the C1-C8 alkyl contains a hydroxyl and / or amine substituent.

[0019] Preferably, in the phase change type absorbent, the mass percentage of the organic amine is 15-50 wt%, and the mass percentage of the ionic liquid is 15-50 wt%, preferably 25-45 wt%.

[0020] More preferably, the cation in the ionic liquid is selected from pyridinium cations.

[0021] Further, the phase change type absorbent optionally further comprises an organic solvent and / or an auxiliary component;

[0022] Preferably, in the phase change type absorbent, the mass percentage of the organic solvent is 0-70%;

[0023] Preferably, in the phase change type absorbent, the mass percentage of the auxiliary component is 0-30%;

[0024] Preferably, the organic solvent comprises one or more of acetonitrile, ethanol, ethylene glycol, glycerol, propanol, isopropanol, n-butanol, isobutanol, amyl alcohol, dimethyl ether, diethyl ether, dipropyl ether, dibutyl ether, methyl ethyl ether, ethyl propyl ether, propyl butyl ether, polyethylene glycol dimethyl ether, ethyl acetate, butyl acetate, N-methyl-2-pyrrolidone, 2-pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide and sulfolane;

[0025] Preferably, the auxiliary component comprises one or more of corrosion inhibitors, degradation inhibitors, antifoaming agents.

[0026] The present application also provides an integrated capture method for desulfurization and decarbonization of flue gas, which comprises the following steps:

[0027] (1) contacting the flue gas to be treated containing CO2 and SO2 with the phase change type absorbent according to any one of claims 1-8, so that the CO2 and SO2 in the flue gas to be treated are absorbed by the phase change type absorbent, to obtain treated flue gas;

[0028] (2) the phase change type absorbent having absorbed the CO2 and SO2 is phase-separated to form an upper CO2-rich phase and a lower SO2-rich phase;

[0029] The CO2-rich phase and the SO2-rich phase are separately heated and regenerated, to release a gas mainly containing CO2 from the CO2-rich phase and obtain a first regenerated solution, and to release a gas mainly containing SO2 from the SO2-rich phase and obtain a second regenerated solution;

[0030] Preferably, the first regenerated solution and the second regenerated solution are recycled for use in preparing the phase change type absorbent in step (1);

[0031] Preferably, the CO2 volume concentration in the flue gas to be treated is 5-20%, and the SO2 volume concentration is 0.02-5%.

[0032] Preferably, in step (1), the contacting is carried out at a temperature of 10-60℃;

[0033] Preferably, in step (2), the temperature of the CO2-rich phase for the heating regeneration is 80-130℃, and the pressure is 30-190kPa.

[0034] Preferably, in step (2), the temperature of the SO2-rich phase for the heating regeneration is 80-120℃, and the pressure is 10-150kPa.

[0035] The technical solution provided by the present application has the following beneficial effects:

[0036] The phase-change type absorbent provided by the present application is a homogeneous solution before contacting with CO2 and SO2, and is separated into an upper CO2-rich phase and a lower SO2-rich phase by standing after contacting with flue gas containing CO2 and SO2 for absorption of CO2 and SO2. By separating the upper and lower layers and individually performing heating regeneration, CO2 and SO2 can be better desorbed and enriched, and good separation and collection of the two gases can be achieved. Moreover, the required regeneration conditions are mild, and the regeneration energy consumption is low. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 It is a schematic diagram of the action principle of the phase-change type absorbent.

[0038] Figure 2 It is a schematic diagram of the absorption bottle used in the examples. DETAILED DESCRIPTION

[0039] In order to facilitate the understanding of the present application, the present application will be further described below in conjunction with examples. It should be understood that the following examples are only for better understanding of the present application, and do not mean that the present application is limited to the following examples only.

[0040] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The term "and / or" as can be used herein includes any and all combinations of one or more of the associated listed items.

[0041] If the specific experimental steps or conditions are not specified in the examples, the corresponding conventional experimental steps can be operated or the conditions can be used. If the reagents or instruments used are not specified by the manufacturer, they are all conventional products that can be obtained by purchase.

[0042] In one aspect, the present application provides a phase-change type absorbent for flue gas desulfurization and decarburization, which is an aqueous solution containing 5-80wt% of an organic amine and 5-80wt% of an ionic liquid.

[0043] The ionic liquid includes an anion and a cation.

[0044] the cation is selected from one or more of imidazolium cations, pyrrolidinium cations, quaternary ammonium cations, pyridinium cations, piperidinium cations, piperazinium cations, and pyrrolium cations;

[0045] the anion is selected from one or more of hydrophobic fluorine-containing anions, hydrophobic sulfonate-containing anions, and hydrophobic fatty acid anions.

[0046] The phase change absorbent provided by the present application is a homogeneous solution before being contacted with CO2 and SO2, and after being contacted with flue gas containing CO2 and SO2 for CO2 and SO2 absorption treatment, the phase is separated into an upper CO2-rich phase and a lower SO2-rich phase by standing, wherein the upper layer is an organic amine phase that has mainly absorbed CO2 and part of SO2; and the lower layer is an ionic liquid phase that has mainly absorbed SO2. By separating the upper layer and the lower layer and individually heating and regenerating, CO2 and SO2 can be better desorbed and enriched, and good separation and collection of the two gases can be achieved. Moreover, the required regeneration conditions are mild, and the regeneration energy consumption is low.

[0047] In a preferred embodiment, the cation in the ionic liquid is selected from one or more of cations having the following structural formulae (II)-(VIII):

[0048]

[0049]

[0050] R1-R8 in the structural formulae (II)-(VIII) are independently selected from H and C1-C8 alkyl groups; preferably, the C1-C8 alkyl groups contain ether groups, hydroxyl groups, nitrile groups, and / or amine groups. 48 are independently selected from H and C1-C8 alkyl groups; preferably, the C1-C8 alkyl groups contain ether groups, hydroxyl groups, nitrile groups, and / or amine groups.

[0051] In a more preferred embodiment, the cation in the ionic liquid has C1-C8 alkyl groups containing ether groups, hydroxyl groups, nitrile groups, and / or amine groups, wherein the number of ether groups, hydroxyl groups, nitrile groups, and / or amine groups can be one or more. Preferably, the ionic liquid with the cation containing these groups is used to facilitate better absorption effect and phase separation effect when absorbing sulfur dioxide and carbon dioxide simultaneously.

[0052] In a more preferred embodiment, the cation in the ionic liquid is selected from pyridinium cations. Preferably, the ionic liquid is used to further improve the loading rate of sulfur dioxide in the lower layer obtained by phase separation. Further preferably, the pyridinium cation has C1-C8 alkyl groups containing ether groups, hydroxyl groups, nitrile groups, and / or amine groups, wherein the number of ether groups, hydroxyl groups, nitrile groups, and / or amine groups can be one or more. Preferably, the ionic liquid is used to facilitate better absorption effect and phase separation effect when absorbing sulfur dioxide and carbon dioxide simultaneously.

[0053] In preferred embodiments, the anion in the ionic liquid is selected from one or more of BF4 - , PF6 - , CH3(CH2) p COO - , C8H 17 SO4 - , C4F9SO3 - , CF3SO3 - , CF3(CF2) q SO3 - , (CF3SO2)3C - , (C2F5SO2)2N - , (CF3SO2)2N - , CH3CH(OH)COO - , dodecylsulfonate, benzenesulfonate and p-toluenesulfonate, wherein p, q are each independently an integer from 0 to 12.

[0054] The preferred ionic liquid is used in the phase change absorbent of the present application, and the capture effect is better, and the required conditions for regeneration are mild, which is particularly beneficial to reduce the regeneration energy consumption of the SO2-rich phase.

[0055] In the phase change absorbent of the present application, the organic amine used can be one or more of primary amine, secondary amine and tertiary amine.

[0056] In some embodiments, the organic amine is selected from one or more of the compounds having the following structural formula (I):

[0057]

[0058] R1-R5 in the structural formula (I) are each independently selected from H, hydroxyl or C1-C8 alkyl, and optionally, some of R1-R5 form a ring; preferably, in the structural formula (I), the C1-C8 alkyl contains a hydroxyl and / or amine group substituent, and the number of the hydroxyl and / or amine group substituent can be one or more.

[0059] In preferred embodiments, the C1-C8 alkyl in the organic amine contains a hydroxyl and / or amine group substituent. The use of the preferred organic amine is beneficial to obtain a better capture effect.

[0060] In preferred embodiments, the mass percentage of the organic amine in the phase change type absorbent is 15-50 wt% (e.g., 15 wt%, 20 wt%, 25 wt%, 30 wt%, 40 wt%, 45 wt%, 50 wt%, etc.), and the mass percentage of the ionic liquid is 15-50 wt% (e.g., 15 wt%, 20 wt%, 25 wt%, 30 wt%, 40 wt%, 45 wt%, 50 wt%, etc.). In the phase change type absorbent of the present application, the preferred amounts of the organic amine and the ionic liquid are used in combination, which is conducive to better achieving two-phase separation in the process of simultaneously absorbing carbon dioxide and sulfur dioxide, while taking into account better carbon dioxide and sulfur dioxide capture effects and better total sulfur dioxide capture amounts. When the amounts of the organic amine and the ionic liquid are higher than the preferred amounts, the difficulty of subsequent phase separation and other operations will be increased, and it is not easy to take into account better total sulfur dioxide capture amounts. Further preferably, the mass percentage of the ionic liquid is 25-45%. Using a more preferred ionic liquid proportion is conducive to further improving the sulfur dioxide loading amount in the ionic liquid phase, while taking into account relatively good carbon dioxide loading amounts in the organic amine phase and relatively good total sulfur dioxide capture amounts. More preferably, in the phase change type absorbent, the mass percentage of the organic amine is 15-50 wt%, the mass percentage of the ionic liquid is 15-50 wt%, and the cation in the ionic liquid is selected from pyridine-based cations. Using this preferred scheme can take into account good carbon dioxide loading amounts in the organic amine phase and good total sulfur dioxide capture amounts, while obtaining better sulfur dioxide loading amounts in the ionic liquid phase.

[0061] In some embodiments, the phase change type absorbent further optionally includes an organic solvent and / or an auxiliary component.

[0062] In some embodiments, in the phase change type absorbent, the mass percentage of the organic solvent is 0-70%.

[0063] In some embodiments, in the phase change type absorbent, the mass percentage of the auxiliary component is 0-30%.

[0064] In some embodiments, the organic solvent includes one or more of acetonitrile, ethanol, ethylene glycol, glycerol, propanol, isopropanol, n-butanol, isobutanol, pentanol, dimethyl ether, diethyl ether, dipropyl ether, dibutyl ether, methyl ethyl ether, ethyl propyl ether, propyl butyl ether, polyethylene glycol dimethyl ether, ethyl acetate, butyl acetate, N-methyl-2-pyrrolidone, 2-pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, and sulfolane.

[0065] In some embodiments, the auxiliary components include one or more of corrosion inhibitors, degradation inhibitors, antifoaming agents, and the like, which can employ corresponding components known in the art, for example, the corrosion inhibitors can be copper carbonate, sodium thiosulfate, sodium sulfite, methionine, 2-mercaptobenzimidazole, etc., the degradation inhibitors can be sodium metavanadate, potassium dichromate, ethylenediaminetetraacetic acid, acetaldoxime, sodium sulfite, etc., the antifoaming agents can be organosilicon, etc.

[0066] The present application also provides an integrated capture method for desulfurization and decarbonization of flue gas, which comprises the following steps:

[0067] (1) contacting the flue gas containing CO2 and SO2 to be treated with the phase-change absorbent as described above to allow the CO2 and SO2 in the flue gas to be treated to be absorbed by the phase-change absorbent, thereby obtaining treated flue gas;

[0068] (2) the phase-change absorbent having absorbed the CO2 and SO2 is separated into an upper CO2-rich phase and a lower SO2-rich phase;

[0069] the CO2-rich phase and the SO2-rich phase are heated and regenerated respectively, thereby releasing a gas mainly containing CO2 from the CO2-rich phase and obtaining a first regenerated solution, and releasing a gas mainly containing SO2 from the SO2-rich phase and obtaining a second regenerated solution;

[0070] The phase-change absorbent is as described above, and the description of the phase-change absorbent is specifically described above and will not be repeated here.

[0071] By using the method of the present application to treat the flue gas containing CO2 and SO2, the present inventors have found that, after the phase-change absorbent used in the present application is contacted with the flue gas containing both CO2 and SO2, the phase-change absorbent will undergo phase change from a homogeneous phase to two layers by absorbing CO2 and SO2, and after separation (for example, separation after standing), the upper layer is a CO2-rich phase, which is an organic amine phase mainly absorbing CO2 and part of SO2, and the lower layer is a SO2-rich phase, which is an ionic liquid phase mainly absorbing SO2. The method of the present application can realize the physical separation of the SO2-rich phase and the CO2-rich phase, and the two phases can be regenerated separately. In the process of heating and regeneration, the organic amine phase in the upper layer desorbs CO2, and the ionic liquid phase in the lower layer desorbs SO2, which can realize good regeneration and separation of CO2 and SO2, and compared with the traditional process, the energy consumption for regeneration, especially the energy consumption for regeneration of the SO2-rich phase, will be greatly reduced. By using the method of the present application in combination with the phase-change absorbent of the present application, high-purity carbon dioxide gas and sulfur dioxide gas can be obtained by treating the flue gas.

[0072] Preferably, the first and second regeneration solutions are recycled for use in the preparation of the phase change absorbent in step (1). After mixing, the first and second regeneration solutions become homogeneous again and can be recycled for use in the treatment of flue gas containing CO2 and SO2, thereby reducing the consumption of absorbent and lowering the cost.

[0073] The phase change absorbent and integrated capture method provided by the present application are particularly suitable for the treatment of flue gas containing 5-20% CO2 and 0.02-5% SO2. After treatment by the capture method of the present application, the flue gas containing relatively low levels of SO2 can be treated to obtain flue gas with a low SO2 content, which can meet the ultra-low emission standard (i.e., less than 35 mg / m 3 ).

[0074] Preferably, in step (1), the contacting is carried out at a temperature of 10-60°C.

[0075] Preferably, in step (2), the CO2-rich phase is subjected to the heating regeneration at a temperature of 80-130°C and a pressure of 30-190 kPa. In some embodiments, after regeneration, the CO2-rich phase has a CO2 loading of 0.001-4 mol CO2 / L and a regeneration rate of >60%, and a SO2 loading of 0.001-5 mol SO2 / L and a regeneration rate of <1%.

[0076] Preferably, in step (2), the SO2-rich phase is subjected to the heating regeneration at a temperature of 80-120°C and a pressure of 10-150 kPa. In some embodiments, after regeneration, the SO2-rich phase has a SO2 loading of 0.0001-0.5 mol SO2 / L and a regeneration rate of >90%.

[0077] In some embodiments, by the method of the present application, the phase change absorbent provided by the present application is used to absorb flue gas containing CO2 and SO2, and the volume ratio of the organic amine phase to the ionic liquid phase formed by phase separation is 1:(0.05-10). In some embodiments, the CO2 loading of the organic amine phase (CO2-rich phase) formed by phase separation is 0.01-10 mol CO2 / L, the SO2 loading is 0.001-5 mol SO2 / L, and the CO2 loading is higher than the SO2 loading; the CO2 loading of the ionic liquid phase (SO2-rich phase) formed by phase separation is 0.001-1 mol CO2 / L, the SO2 loading is 0.01-10 mol SO2 / L, and the SO2 loading is higher than the CO2 loading.

[0078] The present application will be further illustrated by the following examples, but should not be construed as limiting the present application to the examples.

[0079] Raw material description:

[0080] Raw materials such as 1-butylpyridine tetrafluoroborate ([C4Py][BF4]), 1-cyanobutylpyridine tetrafluoroborate ([C4CNPy][BF4]), and 1-butyl-3-methylimidazolium trifluoromethanesulfonate ([Bmim][Tfo]) can all be purchased on the market, for example from manufacturers such as Aladdin, Sinopharm, and TCI.

[0081] Example 1:

[0082] Preparation of phase change absorbent: Weigh 30g of ethanolamine, 50g of water, and 20g of 1-butylpyridine tetrafluoroborate ([C4Py][BF4]) into a 250mL beaker, and stir magnetically for 30 minutes at room temperature to obtain a homogeneous phase change absorbent A (hereinafter referred to as "absorbent A").

[0083] Absorbent absorption gas experiment: The simulated flue gas composition was CO2 12%, SO2 1%, and the balance was N2, all of which were volume concentrations.

[0084] Weigh 20g of absorbent A and place it in a gas absorption bottle, as follows: Figure 2 As shown, the mass of the absorption bottle was accurately weighed before the experiment began. The absorption bottle was placed in a 40℃ water bath, with the absorbent A liquid level 3 cm below the water bath surface. It was kept at a constant temperature and allowed to stabilize for 30 minutes. Simulated flue gas was then introduced into the absorption bottle in the direction of the arrow, with a flow rate set at 0.5 L / min. The tail gas was absorbed using a 1 mol / L NaOH aqueous solution. Every 10 minutes, the absorption bottle was removed, dried, and weighed until absorption saturation was achieved, with the weight remaining constant. The total time required for the above tail gas absorption was 100 minutes. After standing for 10 minutes, the absorbent showed obvious phase separation, with a volume ratio of approximately 4:1 between the upper and lower layers. The upper layer was an organic amine solution phase, and the lower layer was an ionic liquid phase.

[0085] CO2 and SO2 loading titration experiments: The loadings of CO2 and SO2 in the upper and lower layers were determined using an automatic potentiometric titrator (Leici ZDJ-4A). (CO2 was titrated with a dilute sulfuric acid solution with a H ion concentration of 0.1 mol / L, and SO2 was titrated with a 0.1 M I2 solution; subsequent titration operations were performed in accordance with this method). After titration, the CO2 loading in the upper organic amine solution phase was 0.35 mol CO2 / L upper solution volume, and the SO2 loading was 0.02 mol SO2 / L upper solution volume. The CO2 loading in the lower ionic liquid phase was negligible, and the SO2 loading was 0.5 mol SO2 / L lower solution volume.

[0086] Absorbent regeneration experiment: The upper organic amine solution phase and the lower ionic liquid phase obtained from phase separation were transferred to separate absorption bottles. Figure 2The upper solution and the lower solution were heated and desorbed under reduced pressure, respectively. The desorption conditions for the upper solution were 100°C, a system pressure of 50 kPa maintained by a vacuum pump, condensation of the evaporated solvent at the outlet and reflux into the absorption bottle, a regeneration time of 30 min, and a first regenerated solution.

[0087] The desorption conditions for the lower solution were 90°C, a system pressure of 50 kPa maintained by a vacuum pump, condensation of the evaporated solvent at the outlet and reflux into the absorption bottle, a regeneration time of 30 min, and a second regenerated solution.

[0088] The first regenerated solution and the second regenerated solution were titrated by an automatic potentiometric titrator (Lei Magnet ZDJ-4A), and the CO2 loading in the first regenerated solution was 0.11 mol CO2 / L first regenerated solution, and the SO2 loading was 0.02 mol SO2 / L first regenerated solution; the CO2 loading in the second regenerated solution was negligible, and the SO2 loading was 0.05 mol SO2 / L second regenerated solution.

[0089] The gas desorbed from the upper solution contained >99% CO2 by volume and <1% SO2 by volume;

[0090] The gas desorbed from the lower solution contained <1% CO2 by volume and >99% SO2 by volume.

[0091] Example 2 (compared with Example 1, the ionic liquid is different):

[0092] The phase change type absorbent was prepared by weighing 30 g of ethanolamine, 50 g of water, and 20 g of 1-cyanobutylpyridine tetrafluoroborate ([C4CNPy][BF4]) into a 250 mL beaker, and magnetically stirring at room temperature for 30 minutes to obtain a homogeneous phase of phase change type absorbent B (hereinafter referred to as "absorbent B").

[0093] The absorbent gas absorption experiment was performed by weighing 20 g of absorbent B into a gas absorption bottle, and

[0094] The absorbent gas absorption experiment was performed by weighing 20 g of absorbent B into a gas absorption bottle, and Figure 2As shown, the mass of the absorption bottle was accurately weighed before starting the experiment. The absorption bottle was placed in a 40℃ water bath, with the absorbent B liquid level 3 cm below the water bath surface. It was kept at a constant temperature and allowed to stabilize for 30 minutes. Simulated flue gas was then introduced into the absorption bottle in the direction of the arrow, with a flow rate set at 0.5 L / min. The tail gas was absorbed using a 1 mol / L NaOH aqueous solution. Every 10 minutes, the absorption bottle was removed, dried, and weighed until absorption saturation was achieved, with the weight remaining constant. The total time required for the above tail gas absorption was 100 minutes. After standing for 10 minutes, the absorbent showed obvious phase separation, with a volume ratio of approximately 4:1 between the upper and lower layers. The upper layer was an organic amine solution phase, and the lower layer was an ionic liquid phase.

[0095] CO2 and SO2 loading titration experiment: The loading of CO2 and SO2 in the upper and lower layers was determined using an automatic potentiometric titrator (Leici ZDJ-4A). After titration, the CO2 loading in the upper organic amine solution phase was 0.34 mol CO2 / L upper solution volume, and the SO2 loading was 0.015 mol SO2 / L upper solution volume. The CO2 loading in the lower ionic liquid phase was negligible, and the SO2 loading was 0.65 mol SO2 / L lower solution volume.

[0096] Absorbent regeneration experiment: The upper organic amine solution phase and the lower ionic liquid phase obtained from phase separation were transferred to separate absorption bottles. Figure 2 The absorption bottles shown were subjected to heating and desorption under reduced pressure. The desorption conditions for the upper layer solution were 100°C, and the system pressure was maintained at 50 kPa using a vacuum pump. The evaporated solvent was condensed at the outlet and refluxed back into the absorption bottle. The regeneration time was 30 min, and the resulting regenerated solution was the first regenerated solution.

[0097] The desorption conditions of the lower layer solution are 90℃, the system pressure is maintained at 50kPa using a vacuum pump, the evaporated solvent is condensed and refluxed back into the absorption bottle at the outlet, the regeneration time is 30min, and the resulting regenerated solution is the second regenerated solution.

[0098] The first and second regenerated solutions were titrated using an automatic potentiometric titrator (Leici ZDJ-4A). The CO2 loading in the first regenerated solution was 0.11 mol CO2 / L, and the SO2 loading was 0.015 mol SO2 / L. The CO2 loading in the second regenerated solution was negligible, and the SO2 loading was 0.12 mol SO2 / L.

[0099] The gas obtained from the desorption of the upper solution has a CO2 volume concentration of >99% and an SO2 volume concentration of <1%.

[0100] The gas obtained from the desorption of the lower layer solution has a CO2 volume concentration of <1% and an SO2 volume concentration of >99%.

[0101] Compared with Example 1, the preferred ionic liquid is used in this example, and the sulfur dioxide loading in the lower ionic liquid phase is significantly improved.

[0102] Example 3 (ionic liquid content is 40wt% compared with Example 1)

[0103] Refer to Example 1, except that the components and amounts of the phase change absorbent are as follows: ethanolamine 15g, water 45g, 1-butylpyridine tetrafluoroborate ([C4Py][BF4]) 40g. The same is not described.

[0104] 20g of the absorbent was weighed into a gas absorption bottle, and the mass of the absorption bottle was accurately weighed before the experiment started as shown below. Figure 2 The absorption bottle was placed in a 40℃ water bath, the liquid surface of the absorbent was 3cm lower than the water bath surface, and it was kept constant and stable for 30min. The simulated flue gas was introduced into the absorption bottle from the arrow direction, the flow rate was set to 0.5L / min, and the tail gas was absorbed by 1mol / L NaOH aqueous solution. Every 10min, the absorption bottle was taken out, wiped dry and weighed, until the absorption was saturated and the weight was unchanged. The time required for the above tail gas absorption was 100min. After standing for 10min, the absorbent showed obvious phase separation, and the volume ratio of the upper and lower layers was about 3:1. The upper layer was an organic amine solution phase, and the lower layer was an ionic liquid phase.

[0105] CO2, SO2 loading titration experiment: An automatic potentiometric titrator (Lei magnet ZDJ-4A) was used to titrate the CO2 and SO2 loadings in the upper and lower layers. After titration, the CO2 loading in the upper organic amine solution phase was 0.21mol CO2 / L of the upper solution volume, and the SO2 loading was 0.01mol SO2 / L of the upper solution volume; the CO2 loading in the lower ionic liquid phase was negligible, and the SO2 loading was 0.66mol SO2 / L of the lower solution volume.

[0106] Absorbent regeneration experiment: The upper organic amine solution phase and the lower ionic liquid phase obtained by phase separation were heated and decompressed desorption according to Example 1. An automatic potentiometric titrator (Lei magnet ZDJ-4A) was used to titrate the first and second regeneration solutions, respectively. The CO2 loading in the first regeneration solution was 0.11mol CO2 / L of the first regeneration solution, and the SO2 loading was 0.01mol SO2 / L of the first regeneration solution. The CO2 loading in the second regeneration solution was negligible, and the SO2 loading was 0.12mol SO2 / L of the second regeneration solution.

[0107] The gas desorbed from the upper solution: CO2 volume concentration is >99%, SO2 volume concentration is <1%;

[0108] The gas desorbed from the lower solution contains: CO2 volume concentration < 1%, SO2 volume concentration > 99%.

[0109] Compared with Example 1, the preferred proportion of ionic liquid in the absorbent is used, and the sulfur dioxide loading in the lower ionic liquid phase is significantly increased.

[0110] Example 4 (5% organic amine in the absorbent)

[0111] Refer to Example 1, except that the components and amounts of the phase change type absorbent are as follows: ethanolamine 5 g, water 50 g, 1-butylpyridine tetrafluoroborate ([C4Py][BF4]) 45 g.

[0112] Weigh 20 g of absorbent into a gas absorption bottle, as shown below Figure 2 The mass of the absorption bottle is accurately weighed before the experiment starts. The absorption bottle is placed in a 40°C water bath, with the liquid surface of the absorbent being 3 cm lower than the water bath surface. After constant temperature and stable standing for 30 min, the simulated flue gas is introduced into the absorption bottle from the arrow direction, with a flow rate of 0.5 L / min. The tail gas is absorbed by 1 mol / L NaOH aqueous solution. Every 10 min, the absorption bottle is taken out, wiped dry and weighed, until the weight remains unchanged, which indicates that the absorption is saturated. The time required for the above tail gas absorption is 100 min. After standing for 10 min, the absorbent is obviously separated into two phases, with a volume ratio of about 3:1. The upper layer is an organic amine solution phase, and the lower layer is an ionic liquid phase.

[0113] CO2 and SO2 loading titration experiment: An automatic potentiometric titrator (Lei magnet ZDJ-4A) is used to titrate the CO2 and SO2 loadings in the upper and lower layers. After titration, the CO2 loading in the upper organic amine solution phase is 0.13 mol CO2 / L of the upper solution volume, and the SO2 loading is 0.01 mol SO2 / L of the upper solution volume. The CO2 loading in the lower ionic liquid phase can be ignored, and the SO2 loading is 0.65 mol SO2 / L of the lower solution volume.

[0114] Absorbent regeneration experiment: The upper organic amine solution phase and the lower ionic liquid phase obtained by phase separation are heated and desorbed under reduced pressure, according to Example 1. An automatic potentiometric titrator (Lei magnet ZDJ-4A) is used to titrate the first and second regeneration solutions, respectively. The CO2 loading in the first regeneration solution is 0.08 mol CO2 / L of the first regeneration solution, and the SO2 loading is 0.01 mol SO2 / L of the first regeneration solution. The CO2 loading in the second regeneration solution can be ignored, and the SO2 loading is 0.12 mol SO2 / L of the second regeneration solution.

[0115] The gas desorbed from the upper solution contains: CO2 volume concentration > 99%, SO2 volume concentration < 1%;

[0116] The gas desorbed from the lower layer solution: CO2 volume concentration < 1%, SO2 volume concentration > 99%.

[0117] Example 5 (6% of the ionic liquid in the absorbent)

[0118] Refer to Example 1, except that the components and amounts of the phase change type absorbent are as follows: ethanolamine 30 g, water 64 g, 1-butylpyridine tetrafluoroborate ([C4Py][BF4]) 6 g. The same is not described.

[0119] 20 g of absorbent was weighed into a gas absorption bottle, as shown below Figure 2 The mass of the absorption bottle was accurately weighed before the experiment started. The absorption bottle was placed in a 40°C water bath, the liquid level of the absorbent was 3 cm lower than the water bath surface, and it was kept constant for 30 min. The simulated flue gas was introduced into the absorption bottle from the arrow direction, the flow rate was set to 0.5 L / min, and the tail gas was absorbed by 1 mol / L NaOH aqueous solution. Every 10 min, the absorption bottle was taken out, wiped dry and weighed, until the absorption was saturated and the weight was constant. The time required for the above tail gas absorption was 100 min. After 10 min of standing, the absorbent showed obvious phase separation, with a volume ratio of about 12:1 between the upper and lower layers. The upper layer was an organic amine solution phase, and the lower layer was an ionic liquid phase.

[0120] CO2 and SO2 loading titration experiment: An automatic potentiometric titrator (Lei magnet ZDJ-4A) was used to titrate the CO2 and SO2 loadings in the upper and lower layers. After titration, the CO2 loading in the upper organic amine solution phase was 0.34 mol CO2 / L of upper layer solution volume, and the SO2 loading was 0.02 mol SO2 / L of upper layer solution volume; the CO2 loading in the lower ionic liquid phase was negligible, and the SO2 loading was 0.65 mol SO2 / L of lower layer solution volume.

[0121] Absorbent regeneration experiment: The upper organic amine solution phase and the lower ionic liquid phase obtained by phase separation were heated and desorbed under reduced pressure, according to Example 1. An automatic potentiometric titrator (Lei magnet ZDJ-4A) was used to titrate the first and second regeneration solutions, respectively. The CO2 loading in the first regeneration solution was 0.11 mol CO2 / L of first regeneration solution, and the SO2 loading was 0.02 mol SO2 / L of first regeneration solution. The CO2 loading in the second regeneration solution was negligible, and the SO2 loading was 0.12 mol SO2 / L of second regeneration solution.

[0122] The gas desorbed from the upper layer solution: CO2 volume concentration > 99%, SO2 volume concentration < 1%;

[0123] The gas desorbed from the lower solution contains <1% CO2 and >99% SO2 by volume.

[0124] Compared with Example 1, the preferred proportion of ionic liquid is not adopted in the absorbent of the present example, the volume of ionic liquid phase is significantly reduced after phase separation, and the total sulfur dioxide capture amount is reduced.

[0125] Example 6 (using imidazole ionic liquid)

[0126] Refer to Example 1, except that the ionic liquid used is 1-butyl-3-methylimidazolium triflate ([Bmim][Tfo]); the same is not repeated.

[0127] 20 g of absorbent was weighed and placed in a gas absorption bottle, as shown below Figure 2 The mass of the absorption bottle was accurately weighed before the experiment started. The absorption bottle was placed in a 40°C water bath, the liquid surface of the absorbent was 3 cm lower than the water bath surface, and it was kept constant and stable for 30 min. The simulated flue gas was introduced into the absorption bottle from the arrow direction, the flow rate was set to 0.5 L / min, and the tail gas was absorbed by 1 mol / L NaOH aqueous solution. Every 10 min, the absorption bottle was taken out, wiped dry and weighed, until the absorption was saturated and the weight was constant. The time required for the above tail gas absorption was 100 min. After 10 min of standing, the absorbent showed obvious phase separation, and the volume ratio of the upper and lower layers was about 6:1. The upper layer was an organic amine solution phase, and the lower layer was an ionic liquid phase.

[0128] CO2 and SO2 loading titration experiment: An automatic potentiometric titrator (Lei magnet ZDJ-4A) was used to titrate the CO2 and SO2 loadings in the upper and lower layers. After titration, the CO2 loading in the upper organic amine solution phase was 0.35 mol CO2 / L of upper solution volume, and the SO2 loading was 0.01 mol SO2 / L of upper solution volume; the CO2 loading in the lower ionic liquid phase was negligible, and the SO2 loading was 0.46 mol SO2 / L of lower solution volume.

[0129] Absorbent regeneration experiment: Refer to Example 1 to perform heating and reduced pressure desorption of the upper organic amine solution phase and the lower ionic liquid phase obtained by phase separation. Figure 2The absorption bottle shown was used to perform heating and desorption on the upper and lower solution phases, respectively. The upper layer was desorbed at 100℃, with a vacuum pump maintaining the system pressure at 50 kPa. The evaporated solvent was condensed at the outlet and refluxed back into the absorption bottle. The regeneration time was 30 min, and the resulting regenerated solution was the first regenerated solution. The lower layer was desorbed at 90℃, with a vacuum pump maintaining the system pressure at 50 kPa. The evaporated solvent was condensed at the outlet and refluxed back into the absorption bottle. The regeneration time was 30 min, and the resulting regenerated solution was the second regenerated solution. The first and second regenerated solutions were titrated using an automatic potentiometric titrator (Leici ZDJ-4A). The CO2 loading in the first regenerated solution was measured to be 0.11 mol CO2 / L, and the SO2 loading was measured to be 0.01 mol SO2 / L. The CO2 loading in the second regenerated solution was negligible, and the SO2 loading was 0.11 mol SO2 / L.

[0130] The gas obtained from the desorption of the upper solution has a CO2 volume concentration of >99% and an SO2 volume concentration of <1%.

[0131] The gas obtained from the desorption of the lower layer solution has a CO2 volume concentration of <1% and an SO2 volume concentration of >99%.

[0132] Compared with Example 1, this example does not use the preferred ionic liquid, and the sulfur dioxide loading in the lower ionic liquid phase is inferior to that in Example 1.

[0133] Comparative Example 1 (non-ionic liquid):

[0134] Preparation of absorbent: Weigh 30g of ethanolamine and 70g of water into a 250mL beaker, and stir magnetically for 30 minutes at room temperature to form absorbent a.

[0135] Absorbent absorption gas experiment: The simulated flue gas composition was CO2 12%, SO2 1%, and the balance was N2, all of which were volume concentrations.

[0136] Weigh 20g of absorbent a and place it in a gas absorption bottle, such as... Figure 2 As shown, accurately weigh the absorption bottle before starting the experiment. Place the absorption bottle in a 40℃ water bath, with the absorbent a liquid level 3cm below the water bath surface. Maintain the temperature and allow it to stand for 30 minutes to stabilize. Then, introduce simulated flue gas into the absorption bottle in the direction of the arrow, setting the flow rate to 0.5L / min. The tail gas is absorbed using a 1mol / L NaOH aqueous solution. Remove the absorption bottle every 10 minutes, wipe it dry, and weigh it until absorption is saturated and the weight remains constant. The total time required for the above tail gas absorption is 100 minutes. The absorbent does not separate into phases after standing.

[0137] CO2, SO2 loading titration experiment: Automatic potentiometric titrator (Lei magnet ZDJ-4A) was used to titrate the CO2, SO2 loading of the absorption saturated absorbent a. After titration, the CO2 loading was 0.25 mol CO2 / L solvent, and the SO2 loading was 0.2 mol SO2 / L solvent.

[0138] Absorbent regeneration experiment: The absorption bottle shown in Fig. 1 was used to heat and desorb the absorption saturated absorbent a. The solvent desorption conditions were 100 ℃, and the system pressure was maintained at 50 kPa by using a vacuum pump. The evaporated solvent was condensed at the outlet and returned to the absorption bottle. The regeneration time was 30 min. The automatic potentiometric titrator (Lei magnet ZDJ-4A) was used to titrate the regenerated absorbent. The CO2 loading of the regenerated absorbent was 0.11 mol CO2 / L regenerated absorbent, and the SO2 loading was 0.2 mol SO2 / L regenerated absorbent. From the experimental results, it can be seen that under the above regeneration conditions, SO2 is almost not regenerated. Figure 2

[0139] The gas obtained by desorption: the CO2 volume concentration was > 99%, and the SO2 volume concentration was < 1%.

[0140] Comparative Example 2:

[0141] Reference was made to Comparative Example 1, except that the regeneration conditions of the absorption saturated absorbent a were different. Only the regeneration process is described below, and the other processes are the same as those in Comparative Example 1.

[0142] Absorbent regeneration experiment: The absorption bottle shown in Fig. 1 was used to heat and desorb the absorption saturated absorbent a. The solvent desorption conditions were 100 ℃, and the system pressure was maintained at 50 kPa by using a vacuum pump. The evaporated solvent was condensed at the outlet and returned to the absorption bottle. The regeneration time was 30 min. The automatic potentiometric titrator (Lei magnet ZDJ-4A) was used to titrate the regenerated absorbent. The CO2 loading of the regenerated absorbent was 0.11 mol CO2 / L regenerated absorbent, and the SO2 loading was 0.2 mol SO2 / L regenerated absorbent. From the experimental results, it can be seen that under the above regeneration conditions, SO2 is almost not regenerated. Figure 2

[0143] The gas obtained by desorption: the CO2 volume concentration was 85%, and the SO2 volume concentration was 15%.

[0144] Table 1 summarizes the experimental results

[0145]

[0146]

[0147] ​​Note: "Negligible" in Table 1 means below the lower limit of detection of the method and cannot be detected. In the event of any discrepancy between the data in Table 1 and the written description of the preceding examples and comparative examples, the written description of the preceding examples and comparative examples shall prevail.

[0148] It is readily understood that the above-described embodiments are only illustrative of the application, and not intended to limit the present application thereto. Other variations and modifications of the embodiments disclosed herein can be made based on the description disclosed herein, and such changes and modifications are also to be included within the scope of the application. It is therefore not intended to limit the present application to the exact embodiments described above.

Claims

1. A phase change absorbent for flue gas desulfurization and decarbonization, characterized in that, The phase change absorbent is an aqueous solution containing 5-80 wt% organic amine and 5-80 wt% ionic liquid; The ionic liquid includes anions and cations; The cation is selected from one or more of imidazole cations, pyrrolidine cations, quaternary ammonium cations, pyridine cations, piperidine cations, piperazine cations, and pyrrole cations; The anion is selected from one or more of hydrophobic fluorine-containing anions, hydrophobic sulfonate-containing anions, and hydrophobic fatty acid anions.

2. The phase change absorbent according to claim 1, characterized in that, The cation in the ionic liquid is selected from one or more cations having the following structural formulas (II)-(VIII): In the structural formulas (II)-(VIII), R1 to R... 48 Each is independently H or C1-C8 alkyl; preferably, the C1-C8 alkyl contains an ether group, a hydroxyl group, a nitrile group and / or an amino group.

3. The phase change absorbent according to claim 1 or 2, characterized in that, The cation has a C1-C8 alkyl group containing an ether group, a hydroxyl group, a nitrile group and / or an amino group.

4. The phase change absorbent according to any one of claims 1-3, characterized in that, The cations in the ionic liquid are selected from pyridine cations.

5. The phase change absorbent according to any one of claims 1-3, characterized in that, The anion in the ionic liquid is selected from BF4. - PF6 - CH3(CH2) p COO - C8H 17 SO4 - C4F9SO3 - CF3SO3 - CF3 (CF2) q SO3 - (CF3SO2)3C - (C2F5SO2)2N - (CF3SO2)2N - CH3CH(OH)COO - One or more of dodecyl sulfonate, benzene sulfonate and p-toluene sulfonate, wherein p and q are each independently integers from 0 to 12.

6. The phase change absorbent according to any one of claims 1-3, characterized in that, The organic amine is selected from one or more compounds having the following structural formula (I): In the structural formula (I), R1-R5 are each independently selected from H, hydroxyl, or C1-C8 alkyl groups; optionally, some groups in R1-R5 are cyclic; preferably, the C1-C8 alkyl groups contain hydroxyl and / or amino substituents.

7. The phase change absorbent according to any one of claims 1-6, characterized in that, In the phase change absorbent, the organic amine has a mass percentage of 15-50 wt%, and the ionic liquid has a mass percentage of 15-50 wt%, preferably 25-45%. More preferably, the cation in the ionic liquid is selected from pyridine cations.

8. The phase change absorbent according to any one of claims 1-3, characterized in that, The phase change absorbent may also optionally include an organic solvent and / or auxiliary components; Preferably, in the phase change absorbent, the organic solvent accounts for 0-70% by mass; Preferably, in the phase change absorbent, the auxiliary component has a mass percentage of 0-30%; Preferably, the organic solvent includes one or more of acetonitrile, ethanol, ethylene glycol, glycerol, propanol, isopropanol, n-butanol, isobutanol, pentanol, dimethyl ether, diethyl ether, dipropyl ether, dibutyl ether, methyl ethyl ether, ethyl propyl ether, propyl butyl ether, polyethylene glycol dimethyl ether, ethyl acetate, butyl acetate, N-methyl-2-pyrrolidone, 2-pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, and sulfolane. Preferably, the auxiliary components include one or more of corrosion inhibitors, degradation inhibitors, and defoamers.

9. An integrated method for capturing flue gas for desulfurization and decarbonization, characterized in that, The capture method includes the following steps: (1) The flue gas containing CO2 and SO2 is contacted with the phase change absorbent according to any one of claims 1-8, so that the CO2 and SO2 in the flue gas to be treated are absorbed by the phase change absorbent, and the treated flue gas is obtained; (2) The phase change absorbent that has absorbed the CO2 and SO2 is separated into an upper CO2-rich phase and a lower SO2-rich phase; The CO2-rich phase and the SO2-rich phase are respectively heated and regenerated. A gas mainly containing CO2 is released from the CO2-rich phase to obtain a first regeneration solution, and a gas mainly containing SO2 is released from the SO2-rich phase to obtain a second regeneration solution. Preferably, the first regenerated solution and the second regenerated solution are recycled for the preparation of the phase change absorbent in step (1); Preferably, the CO2 volume concentration in the flue gas to be treated is 5-20%, and the SO2 volume concentration is 0.02-5%.

10. The integrated capture method according to claim 9, characterized in that, In step (1), the contact is carried out at a temperature of 10–60°C; And / or, in step (2), the temperature at which the CO2-rich phase is heated and regenerated is 80°C to 130°C, and the pressure is 30 kPa to 190 kPa; And / or, in step (2), the temperature at which the SO2-rich phase is heated for regeneration is 80°C to 120°C, and the pressure is 10 kPa to 150 kPa.

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