Low-concentration CO2 catalytic absorption method and application thereof

Abstract

The invention discloses a low-concentration CO2 catalytic absorption method, and belongs to the technical field of gas separation. The low-concentration CO2 catalytic absorption method comprises the following steps: loading alkaline earth metal oxide MgO, CaO or BaO on the surface of activated carbon to prepare a Lewis base catalyst, and combining an organic amine solvent with the Lewis base catalyst to absorb low-concentration CO2, compared with an existing CO2 absorption method, the method has the advantages that an amino solution CO2 absorption system is improved, the recyclable Lewis base catalyst which is low in cost and high in catalytic activity is prepared, the CO2 absorption capacity and capture rate are improved, the CO2 absorption rate is increased, the investment cost of a capture system can be effectively reduced, and the method is suitable for industrial production. And guidance and reference are provided for engineering design and construction of a carbon capture link.

Description

Technical Field

[0001] The present invention relates to the technical field of gas separation, and in particular to a low-concentration CO2 catalytic absorption method and application thereof. Background Art

[0002] As global energy demand continues to increase, greenhouse gas CO2 produced by industry and power plants can lead to global warming and climate change. The Intergovernmental Panel on Climate Change (IPCC) report pointed out that by the middle of this century, global temperature rise should be controlled at 1.5°C. In order to reduce the concentration of CO2 in the atmosphere, carbon capture, utilization and storage (CCUS) technology is considered to be a promising solution for CO2 emission control. CO2 capture refers to the process of separating CO2 from industrial production, energy utilization or the atmosphere. Chemical absorption is currently the most technically mature and most widely used CO2 capture method in industry. It has good flue gas adaptability and high capture efficiency, accounting for more than 60% of the carbon capture market.

[0003] At present, the absorption effect of the existing chemical absorption method mainly depends on the performance of the absorbent, but the absorbent has problems such as low absorption rate, small absorption capacity, low capture rate, strong corrosiveness, and easy degradation, which affects the absorption performance of the absorbent and increases the operating cost of the device. Since the absorption process of CO2 by the absorbent is an acid-base reaction with slow reaction kinetics, the introduction of catalysts to enhance the absorption effect of CO2 by the absorbent has become an efficient and energy-saving solution. The catalyst can physically increase the mass transfer interface area and chemically provide a reaction pathway with lower activation energy to accelerate the chemical absorption process of CO2.

[0004] Chinese patent CN113332855A discloses a packed absorption tower and carbon capture absorption system for organic amine carbon dioxide capture, including an absorption tower shell; a lean liquid nozzle, a plurality of packing layers and a slurry pool are sequentially arranged from top to bottom in the absorption tower shell, wherein a catalytic layer is arranged between adjacent packing layers, a flue gas inlet is arranged on the side of the bottom of the absorption tower shell, and a clean flue gas outlet is arranged on the top of the absorption tower shell, and the active components in the catalytic layer are one or more of K ions, Na ions and Mg ions. The absorption tower and system can accelerate the absorption rate of CO2, but there are still problems of small absorption capacity and low capture rate. Therefore, in order to further accelerate the CO2 absorption rate, improve the absorption performance of the absorbent, and thus reduce the CO2 capture cost, a low-concentration CO2 catalytic absorption method is developed, which has good industrial application prospects. Summary of the invention

[0005] The present invention aims at solving the problems of low CO2 absorption rate, small absorption capacity and low capture rate in the existing chemical absorption method, and provides a low-concentration CO2 catalytic absorption method and its application. By preparing a Lewis base catalyst with high catalytic activity and combining the Lewis base catalyst with an organic amine solvent to absorb low-concentration CO2, the purpose of accelerating the CO2 absorption rate and improving the CO2 capture rate and absorption capacity is achieved.

[0006] In order to solve the above technical problems, the first aspect of the present invention provides a low-concentration CO2 catalytic absorption method, comprising the following steps:

[0007] S1, providing a supported catalyst; the supported catalyst comprises a carrier and an active component; the active component is an alkaline earth metal oxide;

[0008] S2, providing an organic amine solvent;

[0009] S3, under the action of the supported catalyst provided by S1, the flue gas is reacted with the organic amine solvent provided by S2.

[0010] According to some embodiments of the present invention, in S1, the supported catalyst is a Lewis base catalyst;

[0011] And / or, the carrier is selected from at least one of coconut shell-based activated carbon, fruit shell-based activated carbon, wood-based activated carbon, and coal-based activated carbon; preferably coconut shell-based activated carbon.

[0012] According to some embodiments of the present invention, the alkaline earth metal oxide is selected from at least one of MgO, CaO, and BaO; preferably, the precursor of the rare earth metal oxide is selected from at least one of Mg(NO3)2·6H2O, Ca(NO3)2·4H2O, and Ba(NO3)2.

[0013] The alkaline earth metal oxides such as MgO, CaO, and BaO used in the present invention have unsaturated coordinated O 2- , which can provide rich electrons as Lewis basic sites to enhance the absorption effect of the absorbent on CO2; however, alkaline earth metal oxides are easy to dissolve during long-term operation, and can be loaded onto a carrier to improve the stability and dispersibility of the metal oxides; activated carbon is a type of carbon material with high chemical stability, high thermal stability, developed pore structure, large specific surface area and low cost, and can be used as a catalyst carrier. Therefore, activated carbon can be used as a carrier, and different alkaline earth metal oxides MgO, CaO or BaO can be loaded on its surface to prepare Lewis base catalysts, thereby improving the service life and activity of the catalyst.

[0014] According to some embodiments of the present invention, in S1, the mass fraction of the active component in the supported catalyst is 15 wt% to 35 wt%, preferably 15 wt% to 30 wt%, for example 30 wt%.

[0015] According to some embodiments of the present invention, in S2, the organic amine solvent includes at least two organic amines; preferably, the organic amine is selected from monoethanolamine (MEA), diethanolamine (DEA), triethanolamine (TEA), diisopropanolamine (DIPA), N-methyl-diethanolamine (MDEA), 2-amino-2-methyl-1-propanol (AMP), and piperazine (PZ).

[0016] According to some embodiments of the present invention, the organic amine solvent includes monoethanolamine (MEA) and piperazine (PZ); wherein the molar ratio of monoethanolamine to piperazine is (1:1) to (6:1), preferably (2:1) to (4:1), for example 2:1, 3:1, 4:1.

[0017] According to some embodiments of the present invention, in S2, the organic amine solvent is an organic amine aqueous solution; and / or, in the organic amine solvent, the total amine concentration is 2 mol / L to 7 mol / L, preferably 3 mol / L to 6 mol / L, such as 3 mol / L, 4 mol / L, 5 mol / L, 6 mol / L. In the present invention, the total amine concentration is the ratio of the sum of the amounts of each organic amine substance in the organic amine aqueous solution to the volume of the organic amine aqueous solution, that is, the total amine concentration = the sum of the amounts of each organic amine substance / the volume of the organic amine aqueous solution.

[0018] According to some embodiments of the present invention, in S3, the flue gas is a mixture of N2 and CO2; and / or the volume fraction of CO2 in the flue gas is 5% to 35%, preferably 10% to 25%, for example 15%.

[0019] According to some embodiments of the present invention, in S3, the added amount of the supported catalyst accounts for 10 wt% to 30 wt% of the organic amine solvent, preferably 10 wt% to 20 wt%, for example 10 wt%, 15 wt%, 20 wt%.

[0020] According to some embodiments of the present invention, in S3, the reaction conditions include: temperature of 20°C to 55°C, preferably 30°C to 45°C, for example 40°C; time of 1h to 6h, preferably 1h to 4h, for example 4h.

[0021] The second aspect of the present invention provides an application of the above-mentioned low-concentration CO2 catalytic absorption method in carbon capture.

[0022] According to some embodiments of the present invention, the low-concentration CO2 catalytic absorption method is used for coal-fired flue gas or gas flue gas, and the volume fraction of CO2 in the coal-fired flue gas or gas flue gas is 5% to 35%, preferably 10% to 25%.

[0023] Beneficial effects:

[0024] In the low-concentration CO2 catalytic absorption method of the present invention, since the absorption process of CO2 by the organic amine solvent is an acid-base reaction with slow reaction kinetics, a Lewis base catalyst is introduced to enhance the CO2 absorption effect of the absorbent. The Lewis base catalyst can increase the mass transfer interface area at the physical level and provide a reaction pathway with lower activation energy at the chemical level to accelerate the chemical absorption process of CO2. The use of the Lewis base catalyst in the low-concentration CO2 catalytic absorption method can effectively improve the CO2 loading capacity of the organic amine solvent and improve the capture rate.

[0025] The low-concentration CO2 catalytic absorption method of the present invention solves the problems of low absorption rate, small absorption capacity and low capture rate when using organic amine solvent alone to absorb CO2; and the present invention utilizes a Lewis base catalyst with low cost, high catalytic activity and repeatable recycling, and combines the Lewis base catalyst with an organic amine solvent to absorb CO2, which can effectively improve the CO2 absorption capacity and capture rate, accelerate the CO2 absorption rate, and thus reduce the investment cost of the CO2 absorption system. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the CO2 catalytic absorption reaction process of the present invention.

[0027] Figure 2 It is the N2 adsorption-desorption isotherm diagram of the Lewis base catalysts MgO-AC, CaO-AC and BaO-AC prepared in Examples 2-4 of the present invention. DETAILED DESCRIPTION

[0028] The present invention will be further described below in conjunction with the embodiments, but the present invention is not limited by these embodiments.

[0029] In the present invention, the absorption capacity of CO2 (mol / mol) is the ratio of the amount of CO2 to the sum of the amounts of the organic amines in the organic amine solvent, which is calculated by measuring the mass change of the four-necked flask before and after CO2 absorption or by acid-base titration analysis. The CO2 absorption rate is the ratio of the change in the CO2 absorption capacity within the first 10 minutes of the reaction to the time. The CO2 capture rate refers to the ratio of the amount of absorbed CO2 to the amount of CO2 in the original simulated flue gas, and the expression is:

[0030]

[0031] η-CO2 capture rate, %;

[0032] C in -CO2 volume fraction in the simulated flue gas at the inlet, %;

[0033] C out -CO2 volume fraction in the simulated flue gas at the outlet, %.

[0034] In the present invention, the infrared CO2 gas analyzer is purchased from Beijing Huayun Instrument Co., Ltd., the model is GHX-3010E1, and the measuring range is 0-20%.

[0035] In the present invention, the muffle furnace, four-necked flask, spiral condenser and mass flow meter are all common commercially available products unless otherwise specified.

[0036] In the present invention, monoethanolamine was purchased from Aladdin Reagent Co., Ltd. and the specification was analytical grade.

[0037] In the present invention, piperazine was purchased from Aladdin Reagent Co., Ltd. and the specification was analytical grade.

[0038] In the present invention, coconut shell-based activated carbon was purchased from Nanjing Zhengsen Environmental Technology Co., Ltd., model QH-1200, size 4.0 mm, and apparent density 0.52 g / cm 3 , with a specific surface area of ​​980m 2 / g, with a total pore volume of 0.89 cm 3 / g, and the average pore size is 3.5nm.

[0039] Example 1

[0040] This embodiment provides a low-concentration CO2 absorption method.

[0041] 400 mL of an organic amine aqueous solution MEA-PZ with a total amine concentration of 6 mol / L was prepared, wherein the molar ratio of MEA to PZ was 4:1, and the organic amine aqueous solution was added into a four-necked flask; the reaction temperature was controlled at 40°C by a water bath, (simulated flue gas) N2 and CO2 were mixed and introduced into the four-necked flask, and the volume fraction of CO2 in the mixed gas was controlled to be 15% by a mass flow meter; the mixed gas discharged after the reaction was condensed by a spiral condenser and then discharged, and the outlet CO2 concentration was measured by an infrared CO2 gas analyzer; the organic amine solvent absorbed CO2 for 4 hours and then the reaction was terminated; the organic amine aqueous solution after the reaction was sampled to detect the CO2 absorption capacity, absorption rate and capture rate. The results are shown in Table 2.

[0042] Example 2

[0043] This embodiment provides a low-concentration CO2 catalytic absorption method.

[0044] (1) Preparation of Lewis base catalyst

[0045] 57.6g Mg(NO3)2·6H2O was dissolved in 40mL deionized water, and then 30g coconut shell-based activated carbon was added, stirred and impregnated for 10h, dried overnight, and then dried at 110°C for 6h; the dried sample was placed in a muffle furnace and calcined at 600°C for 5h to obtain a Lewis base catalyst MgO-AC, in which the mass fraction of MgO was 30wt%. The pore structure characteristics of the Lewis base catalyst MgO-AC were analyzed by N2 adsorption method, and the results are shown in Figure 2 And Table 1.

[0046] (2) Catalytic enhancement of CO2 absorption by organic amine solvents

[0047] 400 mL of an organic amine aqueous solution MEA-PZ with a total amine concentration of 6 mol / L was prepared, wherein the molar ratio of MEA to PZ was 4:1, the organic amine aqueous solution was added to a four-necked flask, and 1.68 g of the above-mentioned Lewis base catalyst MgO-AC3 was added (the amount of the Lewis base catalyst added accounted for 20 wt% of the organic amine aqueous solution); the reaction temperature was controlled to 40°C by a water bath, (simulated flue gas) N2 and CO2 were mixed and passed into the four-necked flask, and the volume fraction of CO2 in the mixed gas was controlled to be 15% by a mass flow meter; the mixed gas discharged after the reaction was condensed by a spiral condenser and then discharged, and the outlet CO2 concentration was measured by an infrared CO2 gas analyzer; the catalytic organic amine solvent absorbed CO2 for 4 hours and then the reaction was terminated; the organic amine aqueous solution after the reaction was sampled to detect the CO2 absorption capacity, absorption rate and capture rate, and the statistical absorption results are shown in Table 2.

[0048] Comparative Example 1

[0049] The difference between Comparative Example 1 and Example 2 is that in step (2), 31.68 g of coconut shell-based activated carbon is added instead of the Lewis base catalyst MgO-AC, and other conditions remain unchanged. The statistical absorption results are shown in Table 2.

[0050] Comparative Example 2

[0051] The difference between Comparative Example 2 and Example 2 is that in step (2), 31.68 g of MgO is added instead of the Lewis base catalyst MgO-AC, and other conditions remain unchanged. The statistical absorption results are shown in Table 2.

[0052] Example 3

[0053] This embodiment provides a low-concentration CO2 catalytic absorption method.

[0054] (1) Preparation of Lewis base catalyst

[0055] 37.92gCa(NO3)2·4H2O was dissolved in 40mL deionized water, and then 30g coconut shell-based activated carbon was added, stirred and impregnated for 10h, and then dried overnight, and then dried at 110℃ for 6h. The dried sample was placed in a muffle furnace and calcined at 600℃ for 5h to obtain a Lewis base catalyst CaO-AC, in which the mass fraction of CaO was 30wt%. The pore structure characteristics of the Lewis base catalyst CaO-AC were analyzed by N2 adsorption method, and the results are shown in Figure 2 And Table 1.

[0056] (2) Catalytic organic amine solvent absorption of CO2

[0057] 400 mL of an organic amine aqueous solution MEA-PZ with a total amine concentration of 6 mol / L was prepared, wherein the molar ratio of MEA to PZ was 4:1, the organic amine aqueous solution was added into a four-necked flask, and 1.68 g of the above-mentioned Lewis base catalyst CaO-AC3 was added (the amount of the Lewis base catalyst added accounted for 20 wt% of the organic amine aqueous solution); the reaction temperature was controlled at 40°C by a water bath, (simulated flue gas) N2 and CO2 were mixed and passed into the four-necked flask, and the volume fraction of CO2 in the mixed gas was controlled to be 15% by a mass flow meter; the mixed gas discharged after the reaction was condensed by a spiral condenser and then discharged, and the outlet CO2 concentration was measured by an infrared CO2 gas analyzer; the catalytic organic amine solvent absorbed CO2 for 4 hours and then the reaction was terminated; the organic amine aqueous solution after the reaction was sampled to detect the CO2 absorption capacity, absorption rate and capture rate, and the statistical absorption results are shown in Table 2.

[0058] Comparative Example 3

[0059] The difference between Comparative Example 3 and Example 3 is that in step (2), 31.68 g of CaO is added instead of the Lewis base catalyst CaO-AC, and other conditions remain unchanged. The statistical absorption results are shown in Table 2.

[0060] Example 4

[0061] This embodiment provides a low-concentration CO2 catalytic absorption method.

[0062] (1) Preparation of Lewis base catalyst

[0063] 15.33g Ba(NO3)2 was dissolved in 40mL deionized water, and then 30g coconut shell-based activated carbon was added, stirred and impregnated for 10h, and then dried overnight, and then dried at 110℃ for 6h. The dried sample was placed in a muffle furnace and calcined at 600℃ for 5h to obtain a Lewis base catalyst BaO-AC, in which the mass fraction of BaO was 30wt%. The pore structure characteristics of the Lewis base catalyst BaO-AC were analyzed by N2 adsorption method, and the results are shown in Figure 2 And Table 1.

[0064] (2) Catalytic organic amine solvent absorption of CO2

[0065] 400 mL of an organic amine aqueous solution MEA-PZ with a total amine concentration of 6 mol / L was prepared, wherein the molar ratio of MEA to PZ was 4:1, the organic amine aqueous solution was added to a four-necked flask, and 1.68 g of the above-mentioned Lewis base catalyst BaO-AC3 was added (the amount of the Lewis base catalyst added accounted for 20 wt% of the organic amine aqueous solution); the reaction temperature was controlled to 40°C by a water bath, (simulated flue gas) N2 and CO2 were mixed and passed into the four-necked flask, and the volume fraction of CO2 in the mixed gas was controlled to be 15% by a mass flow meter; the mixed gas discharged after the reaction was condensed by a spiral condenser and then discharged, and the outlet CO2 concentration was measured by an infrared CO2 gas analyzer; the catalytic organic amine solvent absorbed CO2 for 4 hours and then the reaction was terminated; the organic amine aqueous solution after the reaction was sampled to detect the CO2 absorption capacity, absorption rate and capture rate, and the statistical absorption results are shown in Table 2.

[0066] Comparative Example 4

[0067] The difference between Comparative Example 4 and Example 4 is that in step (2), 31.68 g of BaO is added instead of the Lewis base catalyst BaO-AC, and other conditions remain unchanged. The statistical absorption results are shown in Table 2.

[0068] Table 1

[0069]

[0070] It can be seen from Table 1 that the specific surface area, total pore volume and average pore diameter of the Lewis base catalyst prepared by coconut shell-based activated carbon loaded with alkaline earth metal oxide in Examples 2-4 are all decreased to a certain extent compared with coconut shell-based activated carbon, indicating that the active components will block part of the pore structure of the activated carbon; in addition, the specific surface area, total pore volume and average pore diameter of the Lewis base catalyst MgO-AC prepared in Example 2 are higher than those of the Lewis base catalysts CaO-AC and BaO-AC prepared in Examples 3 and 4, indicating that the Lewis base catalyst MgO-AC has a porous structure with more developed pores.

[0071] Further, the N2 adsorption-desorption isotherms of the Lewis base catalysts MgO-AC, CaO-AC and BaO-AC prepared in Examples 2-4 of the present invention are shown in FIG. Figure 2 ) It can be seen that the N2 adsorption-desorption isotherms of the Lewis base catalysts prepared in Examples 2-4 are all type IV isotherms. When the P / P0 value is greater than 0.4, the adsorption branch and the desorption branch of the catalyst sample form a hysteresis loop, indicating that the Lewis base catalysts prepared in Examples 2-4 contain a mesoporous structure.

[0072] Table 2

[0073]

[0074] As shown in Table 2, in Example 1, only under the action of organic amine solvent, the CO2 absorption capacity is 0.67 mol / mol, the CO2 absorption rate is 4.35 mmol / mol·min, and the CO2 capture rate is 81.58%, indicating that the CO2 absorption effect of using organic amine solvent alone is general; in Comparative Examples 1-4, after adding a single coconut shell-based activated carbon (AC) or alkaline earth metal oxide (MgO, CaO, BaO) as a catalyst to the organic amine solvent, the CO2 absorption capacity, absorption rate and capture rate are increased; in Examples 2-4 After adding Lewis base catalysts MgO-AC, CaO-AC and BaO-AC to the organic amine solvent respectively, the absorption capacity and capture rate of CO2 were significantly improved, and the CO2 absorption rate was accelerated, which shows that the catalytic performance of the Lewis base catalysts prepared in Examples 2-4 is better than that of a single catalyst; in particular, after adding Lewis base catalyst MgO-AC to the organic amine solvent in Example 2, the reaction system has the best absorption effect on CO2, the CO2 absorption capacity can be increased by 18%, the CO2 absorption rate can be increased by 43%, and the CO2 capture rate can be increased by 16%.

[0075] Among the above, the Lewis base catalysts prepared in Examples 2-4 exhibit excellent catalytic activity due to their excellent electron donating ability, porous surface structure and large specific surface area, which helps to improve the CO2 absorption process and promote the formation of carbamate and bicarbonate products.

[0076] Embodiment 5-6

[0077] The difference between Example 5-6 and Example 2 is that different amounts of MgO-AC catalyst are used: specifically, the amount of MgO-AC catalyst is used as a variable for the experiment, and the amount of MgO-AC catalyst added to the catalytic absorption system is 10wt% and 15wt% of the organic amine solvent, respectively, and other conditions remain unchanged. The statistical results are shown in Table 3 below.

[0078] Table 3

[0079] Example Example 5 Example 6 MgO-AC catalyst dosage (wt%) 10 15 <![CDATA[CO2 absorption capacity (mol / mol)]]> 0.71 0.74 <![CDATA[CO2 absorption rate (mmol / mol·min)]]> 5.94 6.03 <![CDATA[CO2 capture rate (%)]]> 90.85 91.57

[0080] It can be seen from Table 3 that when the dosage of MgO-AC catalyst is in the range of 10wt% to 15wt%, the absorption capacity of CO2 can reach 0.71mol / mol to 0.74mol / mol, the absorption rate of CO2 can reach 5.94mmol / mol·min to 6.03mmol / mol·min, and the CO2 capture rate can reach 90.85% to 91.57%; this shows that the Lewis base catalyst MgO-AC can provide a porous surface and abundant active sites, promote the formation of carbamate and bicarbonate, thereby improving the absorption rate, absorption capacity and capture rate of CO2 by the organic amine solvent.

[0081] Embodiment 7-9

[0082] The difference between Examples 7-9 and Example 2 is that different concentrations of organic amine aqueous solutions MEA-PZ are used; specifically, the total amine concentration of the organic amine solvent MEA-PZ is used as a variable for the experiment, and the total amine concentration of the organic amine solvent MEA-PZ in the catalytic absorption system is set to 3 mol / L, 4 mol / L, and 5 mol / L, respectively, while other conditions remain unchanged. The effect of total amine concentration on CO2 absorption capacity, absorption rate and capture rate is shown in Table 4.

[0083] Table 4

[0084] Example Example 7 Example 8 Example 9 MEA concentration (mol / L) 2.4 3.2 4 PZ concentration (mol / L) 0.6 0.8 1 <![CDATA[CO2 absorption capacity (mol / mol)]]> 0.69 0.72 0.75 <![CDATA[CO2 absorption rate (mmol / mol·min)]]> 4.85 5.56 6.07 <![CDATA[CO2 capture rate (%)]]> 89.74 91.37 92.24

[0085] It can be seen from Table 4 that when the total amine concentration of the organic amine solvent MEA-PZ is in the range of 3 mol / L to 5 mol / L, the absorption capacity of CO2 can reach 0.69 mol / mol to 0.75 mol / mol, the absorption rate of CO2 can reach 4.85 mmol / mol·min to 6.07 mmol / mol·min, and the CO2 capture rate can reach 89.74% to 92.24%. This shows that increasing the total amine concentration of the organic amine solvent MEA-PZ can increase the absorbent concentration at the liquid membrane interface and increase the driving force for CO2 mass transfer, thereby accelerating the reaction rate of the organic amine and CO2 and improving the absorption capacity and capture rate of CO2.

[0086] Embodiment 10-11

[0087] The difference between Examples 10-12 and Example 2 is that the molar ratio of MEA to PZ in the organic amine solvent is different; specifically, the molar ratio of MEA to PZ is used as a variable for experiment, and the molar ratio of MEA to PZ is set to 2:1 and 3:1 respectively, and other experimental conditions remain unchanged. The effect of the molar ratio of MEA to PZ on the CO2 absorption capacity, absorption rate and capture rate is shown in Table 5.

[0088] Table 5

[0089] Example Example 10 Embodiment 11 MEA to PZ molar ratio 2：1 3：1 <![CDATA[CO2 absorption capacity (mol / mol)]]> 0.72 0.75 <![CDATA[CO2 absorption rate (mmol / mol·min)]]> 5.74 5.98 <![CDATA[CO2 capture rate (%)]]> 91.15 92.74

[0090] It can be seen from Table 5 that when the molar ratio of MEA to PZ is in the range of (2:1) to (3:1), the absorption capacity of CO2 can reach 0.72 mol / mol to 0.75 mol / mol, the absorption rate of CO2 can reach 5.74 mmol / mol·min to 5.98 mmol / mol·min, and the CO2 capture rate can reach 91.15% to 92.74%. This shows that within this molar ratio range, the organic amine solvent MEA-PZ has a good absorption effect on low-concentration CO2 and has a high CO2 capture rate.

[0091] Examples 12-19

[0092] The difference between Examples 12-16 and Example 2 is that the volume fraction of CO2 in the simulated flue gas is different; specifically, the volume fraction of CO2 in the simulated flue gas is used as a variable for experiments, and the volume fraction of CO2 in the simulated flue gas is set to 2%, 5%, 10%, 20%, 25%, 30%, 35%, and 40%, respectively. The other experimental conditions remain unchanged. The effect of the volume fraction of CO2 in the simulated flue gas on the CO2 absorption capacity, absorption rate and capture rate is shown in Table 6.

[0093] Table 6

[0094]

[0095] It can be seen from Table 6 that when the volume fraction of CO2 in the simulated flue gas is in the range of 5% to 35%, the absorption capacity of CO2 can reach 0.63mol / mol~0.83mol / mol, the absorption rate of CO2 can reach 5.57mmol / mol·min~6.63mmol / mol·min, and the CO2 capture rate can reach 89.73%~96.11%; this shows that in a wider range of CO2 volume fraction (5%~35%), the organic amine solvent MEA-PZ has better absorption performance for CO2, and has a larger absorption capacity, absorption rate and capture rate; in addition, when the volume fraction of CO2 is lower than 5% or higher than 35%, the absorption performance of CO2 by the organic amine solvent MEA-PZ is lower.

[0096] It should be noted that the embodiments described above are only used to explain the present invention and do not constitute any limitation to the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory words, rather than restrictive words. The present invention may be modified as specified within the scope of the claims of the present invention, and the present invention may be revised without departing from the scope and spirit of the present invention. Although the present invention described therein relates to specific methods, materials and embodiments, it does not mean that the present invention is limited to the specific examples disclosed therein, on the contrary, the present invention can be extended to all other methods and applications with the same functions.

Claims

1. A low concentration CO2 catalytic absorption method, characterized in that: The following steps are involved: S1, providing a supported catalyst; the supported catalyst comprises a carrier and an active component; the active component is an alkaline earth metal oxide; S2, providing an organic amine solvent; S3, under the action of the supported catalyst provided by S1, the flue gas is reacted with the organic amine solvent provided by S2.

2. The low concentration CO2 catalytic absorption method according to claim 1, characterized in that: In S1, the supported catalyst is a Lewis base catalyst; And / or, the carrier is selected from at least one of coconut shell-based activated carbon, fruit shell-based activated carbon, wood-based activated carbon, and coal-based activated carbon; And / or, the alkaline earth metal oxide is selected from at least one of MgO, CaO, and BaO; preferably, the precursor of the rare earth metal oxide is selected from at least one of Mg(NO3)2·6H2O, Ca(NO3)2·4H2O, and Ba(NO3)2.

3. The low concentration CO2 catalytic absorption method according to claim 1 or 2, characterized in that: In S1, the mass fraction of the active component in the supported catalyst is 15wt% to 35wt%, preferably 15wt% to 25wt%.

4. The low concentration CO2 catalytic absorption method according to any one of claims 1 to 3, characterized in that: In S2, the organic amine solvent includes at least two organic amines; preferably, the organic amine is selected from monoethanolamine, diethanolamine, triethanolamine, diisopropanolamine, N-methyl-diethanolamine, 2-amino-2-methyl-1-propanol, and piperazine.

5. The low concentration CO2 catalytic absorption method according to any one of claims 1 to 4, characterized in that: In S2, the organic amine solvent is an organic amine aqueous solution; and / or, the total amine concentration in the organic amine solvent is 2 mol / L to 7 mol / L, preferably 3 mol / L to 6 mol / L.

6. The low concentration CO2 catalytic absorption method according to any one of claims 1 to 5, characterized in that: In S3, the flue gas is a mixture of N2 and CO2; and / or the volume fraction of CO2 in the flue gas is 5% to 35%, preferably 10% to 25%.

7. The low concentration CO2 catalytic absorption method according to any one of claims 1 to 6, characterized in that: In S3, the added amount of the supported catalyst accounts for 10 wt% to 30 wt% of the organic amine solvent, preferably 10 wt% to 20 wt%.

8. The low concentration CO2 catalytic absorption method according to any one of claims 1 to 7, characterized in that: In S3, the reaction conditions include: temperature of 20°C to 55°C, preferably 30°C to 45°C; time of 1h to 6h, preferably 1h to 4h.

9. An application of the low-concentration CO2 catalytic absorption method according to any one of claims 1 to 8 in carbon capture, preferably for coal-fired flue gas or gas flue gas; further preferably, the volume fraction of CO2 in the coal-fired flue gas or gas flue gas is 5% to 35%, preferably 10% to 25%.

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