A method for highly selective adsorption of low partial pressure CO2 using ultraporous azole ionic liquid materials

Abstract

This invention relates to a method for highly selective adsorption of low partial pressure CO2 using an ultraporous azole ionic liquid material, belonging to the field of gas separation and purification technology. The ultraporous ionic liquid material is an ionic adsorbent with selective CO2 adsorption sites and an ultraporous pore distribution, formed by modifying the surface and pore structure of a porous support with multi-site azole ionic liquids. This method is simple to synthesize and easy to scale up. Furthermore, due to the strong chemical interaction between the electronegative sites on the ionic liquid anions and CO2, as well as the ultraporous effect, it synergistically enhances the efficient capture and separation of low partial pressure CO2. Simultaneously, CO2 can be completely desorbed by heating or depressurization. The regenerated ultraporous ionic liquid material is recyclable and exhibits stable performance. This method has advantages such as high capacity and selectivity for low partial pressure CO2, good stability, and recyclability, and has great potential for application in CO2 capture and purification separation.

Description

Technical Field

[0001] This invention relates to the field of gas separation and purification technology, and in particular to a method for highly selectively capturing low partial pressure CO2 using an ultraporous azole ionic liquid material. The ultraporous azole ionic liquid material is a novel adsorbent material formed by loading an azole functional ionic liquid onto a microporous or mesoporous solid material. It achieves highly selective capture and separation of low partial pressure CO2 through the synergistic enhancement of the multi-site interaction of the ionic liquid and the ultraporous effect of the material. Background Technology

[0002] Excessive CO2 emissions are one of the main causes of the greenhouse effect and global warming. To mitigate the environmental problems caused by climate change, countries around the world have formulated a series of carbon reduction measures. Therefore, finding an efficient method for carbon reduction is of great importance.

[0003] Currently, common CO2 capture methods can be divided into absorption, adsorption, and membrane separation. In industry, solvent chemical absorption is widely used and its application technology is relatively mature. However, the amine solutions commonly used in chemical absorption not only corrode equipment during the capture process but also suffer from problems such as excessive regeneration energy consumption and severe degradation. Ionic liquids, as a newly emerging class of absorbents, have lower vapor pressures, higher thermal stability, and designable structures compared to traditional organic solvents. Since Blanchard et al. (Nature, 1999, 399, 28) first reported the high solubility of CO2 in 1-butyl-3-methylimidazolium hexafluorophosphate ([Bmim][PF6]), i.e., 0.72 mol CO2 / mol IL at 40℃ and 93 bar, ionic liquids have received widespread attention as a green CO2 capture medium. Furthermore, novel functional ionic liquids can be designed and synthesized by introducing more CO2 interaction sites into the anions and cations. For example, Bates et al. (J Am Chem Soc, 2002, 124, 926) first synthesized the amino-functional ionic liquid [NH2pbim][BF4] and proposed the reaction mechanism between this ionic liquid and CO. The CO2 absorption capacity of [NH2pbim][BF4] is close to the theoretical maximum value (0.5 mol CO2 / mol IL, i.e., a 1:2 absorption mechanism). However, this functional ionic liquid not only has a high viscosity, but its viscosity also increases dramatically after absorbing CO2, affecting the mass transfer effect and significantly increasing the cost of use. To avoid the problems caused by the high viscosity of ionic liquids, the method of physically or chemically loading ionic liquids onto porous materials to form novel ionic liquid hybrid materials has emerged. Mirzaei et al. (Chemtech, 2018, 1272) prepared a new imidazole ionic liquid material by loading imidazole ionic liquids onto silica and measured the CO2 adsorption capacity of the support and ionic liquid material under different conditions. Compared to silica as the support (CO2 / CH4 selectivity 3.41), this ionic liquid material (50 wt% ionic liquid content) achieves a CO2 / CH4 selectivity of 18.67 at 45 °C and 2.3 MPa. Furthermore, higher ionic liquid content corresponds to lower CO2 adsorption capacity and higher CO2 / CH4 selectivity. Most ionic liquid adsorbents reported to date still suffer from a bottleneck where selectivity and CO2 adsorption capacity are mutually constrained.

[0004] To address the challenges of CO2 adsorption in ionic liquid hybrid materials, this invention proposes modifying the surface and pore structure of a porous support with multi-site azole ionic liquids to prepare an ionic adsorbent with selective CO2 adsorption sites and an ultramicroporous distribution. Due to the strong chemical interaction between the electronegative sites on the anions of the ionic liquid and CO2, along with the ultramicroporous effect, the efficient capture and separation of low-partial-pressure CO2 can be synergistically enhanced. Summary of the Invention

[0005] The purpose of this invention is to provide a method for highly selectively capturing low partial pressure CO2 using an ultraporous azole ionic liquid material. The method is characterized in that the ultraporous azole ionic liquid material is a porous adsorbent formed by loading an azole functional ionic liquid onto a microporous or mesoporous solid material, wherein the general formula of the anion structure in the azole ionic liquid is as follows:

[0006]

[0007] Where K1 and K2 are H, NH2, and C, respectively. n H 2n+1 C n H 2n OH, C n H 2n NH2 (n is an integer, 1≤n≤6), cations are not limited, the mass fraction of ionic liquid in the ultraporous azole ionic liquid material is 5-90wt%, and the microporous or mesoporous structure material is molecular sieve (MCM-41, MCM-48, SBA-15, 13X, ZSM-5, ZSM-22, CMK-3), silica gel, activated carbon, and porous resin.

[0008] According to claim 1, the adsorption temperature of the ultraporous azole ionic liquid material is 10-80℃, and the adsorption pressure is 0.001-10.0 bar. The ultraporous azole ionic liquid material can be regenerated by heating or depressurization, with regeneration conditions of 60-120℃ and regeneration pressure of 0.001-1.0 bar.

[0009] The method according to claim 1 is applicable to the capture and separation of low partial pressure CO2 from flue gas from thermal power plants and chemical tail gas.

[0010] The method described in claim 1 is applicable to the adsorption, separation and removal of extremely low concentrations of NH3 under different conditions such as enclosed spaces, automobile exhaust, and hydrogen fuel cells.

[0011] Compared with existing ionic liquid-modified porous materials, the ultraporous azole ionic liquid material involved in this invention is a novel adsorbent material obtained by loading azole functional ionic liquids onto porous solid materials and modifying them. It primarily enhances CO2 capture and separation under low pressure conditions through the strong chemical interaction between the electronegative sites on the ionic liquid anions and CO2, combined with the ultraporous effect. Furthermore, this ultraporous azole ionic liquid material can be completely desorbed and regenerated by heating or reducing pressure, exhibiting stable recycling performance. This method offers advantages such as simple adsorbent synthesis, high selective separation under low partial pressure CO2 conditions, good stability, and recyclability, overcoming the challenge of the mutual constraint between selectivity and adsorption capacity, and providing a new approach for capture and separation under low partial pressure CO2 conditions. Detailed Implementation

[0012] The technical solution of the present invention will be described in more detail below through specific embodiments. However, the present invention is not limited to the following embodiments. Any variations are included within the technical scope of the present invention without departing from the scope described above.

[0013] Example 1

[0014] 1) Dissolve 0.2 mol of 1,2,4-triazole in 100 mL of deionized water, and add the solution to a round-bottom flask placed in an ice bath. Slowly add 0.2 mol of choline hydroxide solution, and stir the reaction at room temperature for 48 h. After the reaction is complete, rotary evaporate at 65 °C for 4 h to remove most of the water, and dry in a vacuum drying oven at 60 °C for 48 h to remove trace amounts of water, thus obtaining the ionic liquid [Cho][Triz], with a water content of less than 2000 ppm. Dissolve 3 g of [Cho][Triz] in anhydrous ethanol, and then slowly add 7 g of SBA-15 to the solution. Stir at room temperature for 24 h, rotary evaporate at 45 °C to remove most of the ethanol, then sonicate the sample at 45 °C for 2 h, and finally vacuum dry at 60 °C for 48 h to obtain the porous azole ionic liquid material [Cho][Triz]@SBA-15 (ionic liquid content of 30 wt%). With other conditions remaining unchanged, by taking the masses of [Cho][Triz] and SBA-15 as 4g and 6g, 5g and 5g, 6g and 4g, and 7g and 3g respectively, we can obtain porous azole ionic liquid materials [Cho][Triz]@SBA-15 with different ionic liquid contents, namely 40wt%, 50wt%, 60wt%, and 70wt%.

[0015] 2) Dissolve 0.1 mol of 1,2,4-triazole sodium in 100 mL of anhydrous ethanol, and add the solution to a round-bottom flask and place it in an ice bath. Then, dissolve 0.1 mol of 1-ethyl-3-methylimidazolium chloride ([Emim]Cl) in 100 mL of anhydrous ethanol until completely dissolved. Add the solution dropwise slowly and stir at room temperature for 12 h. After the reaction is complete, filter to remove solid NaCl. Remove ethanol and water by rotary evaporation at 65 °C to obtain a pale yellow turbid liquid. Wash with anhydrous ethanol, filter, and rotary evaporate repeatedly to obtain a pale yellow transparent liquid. Dry under vacuum at 60 °C for 48 h to obtain the ionic liquid [Emim][Triz], which has a water content of less than 2000 ppm. Dissolve 3g of [Emim][Triz] in anhydrous ethanol, then slowly add 7g of SBA-15 to the solution. Stir at room temperature for 24h, remove most of the ethanol by rotary evaporation at 45℃, then sonicate the sample at 45℃ for 2h, and finally vacuum dry at 60℃ for 48h to obtain the porous azole ionic liquid material [Emim][Triz]@SBA-15 (ionic liquid content of 30wt%). Keeping other conditions unchanged, take 4g and 6g of [Emim][Triz] and 5g and 5g, 6g and 4g, and 7g and 3g of SBA-15, respectively, to obtain porous azole ionic liquid materials [Emim][Triz]@SBA-15 with different ionic liquid contents of 40wt%, 50wt%, 60wt%, and 70wt%.

[0016] 3) Dissolve 0.2 mol of 1,2,4-triazole in 100 mL of deionized water, add the solution to a round-bottom flask and place it in an ice bath. Slowly add 0.2 mol of tetraethylammonium hydroxide ([N... 2222 The [OH]) solution was stirred at room temperature for 48 hours. After the reaction was complete, most of the water was removed by rotary evaporation at 65°C for 4 hours, and then vacuum dried at 60°C for 48 hours to obtain the ionic liquid [N]. 2222 [Triz], its water content is less than 2000 ppm. 3g of [N] 2222 [Triz] was dissolved in anhydrous ethanol, and then 7g of SBA-15 was slowly added to the solution. The mixture was stirred at room temperature for 24h, and most of the ethanol was removed by rotary evaporation at 45℃. The sample was then sonicated at 45℃ for 2h, and finally vacuum dried at 60℃ for 48h to obtain the porous azole ionic liquid material [N]. 2222 [Triz]@SBA-15 (ionic liquid content 30wt%). Other conditions remain unchanged, take [N 2222 By combining [Triz] with SBA-15 at masses of 4g and 6g, 5g and 5g, 6g and 4g, and 7g and 3g, porous azole ionic liquid materials with different ionic liquid contents can be obtained. 2222[Triz]@SBA-15, with ionic liquid contents of 40wt%, 50wt%, 60wt%, and 70wt%, respectively.

[0017] Example 2

[0018] 1) Using a physical adsorption apparatus, the CO2 adsorption isotherm of 0.10 g of the porous azole ionic liquid material [Cho][Triz]@SBA-15 (ionic liquid content of 30 wt%) synthesized in Example 1 was tested at 25 °C. The CO2 adsorption capacity was 3.06 and 13.44 mg CO2 / g adsorbent at CO2 partial pressures of 0.1 bar and 1 bar, respectively.

[0019] 2) Using a physical adsorption apparatus, the CO2 adsorption isotherm of 0.10 g of the porous azole ionic liquid material [Cho][Triz]@SBA-15 (ionic liquid content of 40 wt%) synthesized in Example 1) was tested at 25 °C. The CO2 adsorption capacity was 25.67 mg CO2 / g adsorbent at CO2 partial pressures of 0.1 bar and 1 bar, respectively.

[0020] 3) Using a physical adsorption apparatus, the CO2 adsorption isotherm of 0.10 g of the porous azole ionic liquid material [Cho][Triz]@SBA-15 (ionic liquid content of 50 wt%) synthesized in Example 1) was tested at 25 °C. The CO2 adsorption capacity was 31.36 and 60.67 mg CO2 / g adsorbent at CO2 partial pressures of 0.1 bar and 1 bar, respectively.

[0021] 4) Using a physical adsorption apparatus, the CO2 adsorption isotherm of 0.10 g of the porous azole ionic liquid material [Cho][Triz]@SBA-15 (ionic liquid content of 60 wt%) synthesized in Example 1) was tested at 25 °C. The CO2 adsorption capacity was 49.33 mg CO2 / g adsorbent at CO2 partial pressures of 0.1 bar and 1 bar, respectively.

[0022] 5) Using a physical adsorption apparatus, the CO2 adsorption isotherm of 0.10 g of the porous azole ionic liquid material [Cho][Triz]@SBA-15 (ionic liquid content of 70 wt%) synthesized in Example 1) was tested at 25 °C. The CO2 adsorption capacity was 62.28 mg CO2 / g adsorbent at CO2 partial pressures of 0.1 bar and 1 bar, respectively.

[0023] Example 3

[0024] 1) Using a physical adsorption apparatus, the CO2 adsorption isotherm of 0.10 g of the porous azole ionic liquid material [Emim][Triz]@SBA-15 (ionic liquid content of 30 wt%) synthesized in Example 1 (2) was tested at 25 °C. The CO2 adsorption capacity was 7.36 and 27.97 mg CO2 / g adsorbent at CO2 partial pressures of 0.1 bar and 1 bar, respectively.

[0025] 2) Using a physical adsorption apparatus, the CO2 adsorption isotherm of 0.10 g of the porous azole ionic liquid material [Emim][Triz]@SBA-15 (ionic liquid content of 40 wt%) synthesized in Example 1 (2) was tested at 25 °C. The CO2 adsorption capacity was 18.90 and 37.63 mg CO2 / g adsorbent at CO2 partial pressures of 0.1 bar and 1 bar, respectively.

[0026] 3) Using a physical adsorption apparatus, the CO2 adsorption isotherm of 0.10 g of the porous azole ionic liquid material [Emim][Triz]@SBA-15 (ionic liquid content of 50 wt%) synthesized in Example 1 (2) was tested at 25 °C. The CO2 adsorption capacity was 32.33 mg CO2 / g adsorbent at CO2 partial pressures of 0.1 bar and 1 bar, respectively.

[0027] 4) Using a physical adsorption apparatus, the CO2 adsorption isotherm of 0.10 g of the porous azole ionic liquid material [Emim][Triz]@SBA-15 (ionic liquid content of 60 wt%) synthesized in Example 1 (2) was tested at 25 °C. The CO2 adsorption capacity was 49.77 mg CO2 / g adsorbent at CO2 partial pressures of 0.1 bar and 1 bar, respectively.

[0028] 5) Using a physical adsorption apparatus, the CO2 adsorption isotherm of 0.10 g of the porous azole ionic liquid material [Emim][Triz]@SBA-15 (ionic liquid content of 70 wt%) synthesized in Example 1 (2) was tested at 25 °C. The CO2 adsorption capacity was 59.51 mg CO2 / g adsorbent at CO2 partial pressures of 0.1 bar and 1 bar, respectively.

[0029] Example 4

[0030] 1) Using a physical adsorption apparatus, the porous azole ionic liquid material [N] synthesized in Example 1, 3) was tested. 2222The CO2 adsorption isotherm of [Triz]@SBA-15 (ionic liquid content of 30wt%) at 25℃ shows that the CO2 adsorption capacity is 2.22 and 11.45 mg CO2 / g adsorbent at CO2 partial pressures of 0.1 bar and 1 bar, respectively.

[0031] 2) Using a physical adsorption apparatus, the porous azole ionic liquid material [N] synthesized in Example 1(3) was tested at 0.10 g. 2222 CO2 adsorption isotherms of [Triz]@SBA-15 (ionic liquid content 40wt%) at 25℃, with CO2 adsorption capacities of 10.69 and 27.90 mg CO2 / g adsorbent at CO2 partial pressures of 0.1 bar and 1 bar, respectively.

[0032] 3) Using a physical adsorption apparatus, the porous azole ionic liquid material [N] synthesized in Example 1(3) was tested at 0.10 g. 2222 CO2 adsorption isotherms of [Triz]@SBA-15 (50wt% ionic liquid content) at 25℃, with CO2 adsorption capacities of 22.19 and 47.48 mg CO2 / g adsorbent at CO2 partial pressures of 0.1 bar and 1 bar, respectively.

[0033] 4) Using a physical adsorption apparatus, the porous azole ionic liquid material [N] synthesized in Example 1, 3) was tested. 2222 The CO2 adsorption isotherm of [Triz]@SBA-15 (60wt% ionic liquid content) at 25℃ showed that the CO2 adsorption capacity was 28.41 and 54.19 mg CO2 / g adsorbent at CO2 partial pressures of 0.1 bar and 1 bar, respectively.

[0034] 5) Using a physical adsorption apparatus, the porous azole ionic liquid material [N] synthesized in Example 1, step 3) was tested. 2222 The CO2 adsorption isotherm of [Triz]@SBA-15 (70wt% ionic liquid content) at 25℃ shows that the CO2 adsorption capacity is 32.12 and 55.78 mg CO2 / g adsorbent at CO2 partial pressures of 0.1 bar and 1 bar, respectively.

[0035] Example 5

[0036] 1) Using a physical adsorption apparatus, the CO2 adsorption isotherm of 0.10 g of the porous azole ionic liquid material [Cho][Triz]@SBA-15 (ionic liquid content 70 wt%) synthesized in Example 1) was tested at 25 °C and 0.001–1.0 bar. After adsorption was complete, N2 was introduced at a flow rate of 100 ml / min, and the desorption temperature was 100 °C. Desorption took approximately 120 min, and CO2 was almost completely released. Following the above steps, adsorption-desorption was repeated 5 times, and the CO2 adsorption performance remained relatively stable. The results are shown in Table 1.

[0037] 2) Using a physical adsorption apparatus, the CO2 adsorption isotherm of 0.10 g of the porous azole ionic liquid material [Emim][Triz]@SBA-15 (ionic liquid content 70 wt%) synthesized in Example 1, 2), was tested at 25 °C and 0.001–1.0 bar. After adsorption was complete, N2 was introduced at a flow rate of 100 ml / min, and the desorption temperature was 100 °C. Desorption took approximately 120 min, and CO2 was almost completely released. Following the above steps, adsorption-desorption was repeated 5 times, and the CO2 adsorption performance remained relatively stable. The results are shown in Table 1.

[0038] Table 1. CO2 adsorption results of porous ionic liquid materials at 25℃ after five cycles

[0039]

[0040] Example 6

[0041] 1) The adsorption breakthrough curves of the binary gas mixture of CO2 and N2 were determined using a multi-component competitive breakthrough adsorption analyzer. Under simulated flue gas mixture (10% CO2 / 90% N2) conditions, 1.0 g of the porous azole ionic liquid material [Cho][Triz]@SBA-15 (ionic liquid content of 70 wt%) synthesized in Example 1) was tested at a temperature of 25 °C, a gas flow rate of 20 mL / min, a pressure of 1.0 bar, a CO2 adsorption capacity of 69.0 mg CO2 / g adsorbent, and a CO2 / N2 selectivity of 588.

[0042] 2) The adsorption breakthrough curves of the CO2 and N2 binary gas mixture were determined using a multi-component competitive breakthrough adsorption analyzer. Under simulated flue gas mixture (20% CO2 / 80% N2) conditions, 1.0 g of the porous azole ionic liquid material [Cho][Triz]@SBA-15 (ionic liquid content of 70 wt%) synthesized in Example 1) was tested at a temperature of 25 °C, a gas flow rate of 20 mL / min, a pressure of 1.0 bar, and the CO2 adsorption capacity was 74.6 mg CO2 / g adsorbent, with a CO2 / N2 selectivity of 245.

[0043] Example 7

[0044] 1) The adsorption breakthrough curves of the binary gas mixture of CO2 and N2 were determined using a multi-component competitive breakthrough adsorption analyzer. Under simulated flue gas mixture (10% CO2 / 90% N2) conditions, 1.0 g of the porous azole ionic liquid material [Emim][Triz]@SBA-15 (ionic liquid content of 70 wt%) synthesized in Example 1(2) was tested at a temperature of 25 °C, a gas flow rate of 20 mL / min, a pressure of 1.0 bar, a CO2 adsorption capacity of 38.6 mg CO2 / g adsorbent, and a CO2 / N2 selectivity of 8962.

[0045] 2) The adsorption breakthrough curves of the CO2 and N2 binary gas mixture were determined using a multi-component competitive breakthrough adsorption analyzer. Under simulated flue gas mixture (20% CO2 / 80% N2) conditions, 1.0 g of the porous azole ionic liquid material [Emim][Triz]@SBA-15 (ionic liquid content of 70 wt%) synthesized in Example 1 (2) was tested at a temperature of 25 °C, a gas flow rate of 20 mL / min, a pressure of 1.0 bar, and the CO2 adsorption capacity was 79.6 mg CO2 / g adsorbent, with a CO2 / N2 selectivity of 36.

[0046] Example 8

[0047] 1) The adsorption breakthrough curves of the CO2 and N2 binary gas mixture were determined using a multi-component competitive breakthrough adsorption analyzer. Under simulated flue gas mixture conditions (10% CO2 / 90% N2), 1.0 g of the porous azole ionic liquid material [N2] synthesized in Example 1, 3) was tested. 2222 [Triz]@SBA-15 (ionic liquid content 70wt%), temperature 25℃, gas flow rate 20mL / min, pressure 1.0bar, CO2 adsorption capacity 16.8mg CO2 / g adsorbent, CO2 / N2 selectivity 247.

[0048] 2) The adsorption breakthrough curves of the CO2 and N2 binary gas mixture were determined using a multi-component competitive breakthrough adsorption analyzer. Under simulated flue gas mixture conditions (20% CO2 / 80% N2), 1.0 g of the porous azole ionic liquid material [N2] synthesized in Example 1(3) was tested. 2222 [Triz]@SBA-15 (ionic liquid content 70wt%), temperature 25℃, gas flow rate 20mL / min, pressure 1.0bar, CO2 adsorption capacity 32.2mg CO= / g adsorbent, CO2 / N2 selectivity 167.

Claims

1. A method for highly selectively capturing low partial pressure CO2 using an ultraporous azole ionic liquid material, characterized in that... Ultraporous azole ionic liquid materials are multi-site ultraporous adsorbents formed by loading azole functional ionic liquids onto porous solid materials. The general formula of the anion structure in the azole functional ionic liquid is as follows: Where K1 and K2 are H, NH2, and C, respectively. n H 2n+1 C n H 2n OH, C n H 2n NH2 (n is an integer, 1≤n≤6), cations are not limited, the mass fraction of ionic liquid in the ultraporous azole ionic liquid material is 5-90wt%, the solid material is a molecular sieve with microporous or mesoporous structure (MCM-41, MCM-48, SBA-15, 13X, ZSM-5, ZSM-22, CMK-3), silica gel, activated carbon, porous resin.

2. The method according to claim 1, wherein the adsorption temperature of the ultraporous azole ionic liquid material is 10–80 °C, and the adsorption pressure is 0.001–10.0 bar.

3. The method according to claim 1, wherein the ultraporous azole ionic liquid material involved is regenerable and recyclable, with regeneration conditions of 60-120°C and regeneration pressure of 0.001-1.0 bar.

4. The method according to claim 1 is applicable to the capture and separation of low partial pressure CO2 from flue gas from thermal power plants and chemical tail gas.

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