Method for catalytic absorption of low concentration co2 and its application

Abstract

The application discloses a kind of low concentration CO2 catalytic absorption method, belong to gas separation technical field;The low concentration CO2 catalytic absorption method of the application, including the preparation of Lewis base catalyst in the surface of activated carbon loading alkali earth metal oxide MgO, CaO or BaO, and the absorption of low concentration CO2 by combining organic amine solvent with Lewis base catalyst;Compared with the existing CO2 absorption method, the application improves the amine-based solution absorption CO2 system, prepares the Lewis base catalyst with low cost, high catalytic activity, recyclable, improves CO2 absorption capacity and capture rate, speeds up CO2 absorption rate, can effectively reduce the investment cost of capture system, provides guidance and reference for the engineering design and construction of carbon capture link.

Description

TECHNICAL FIELD

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

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

[0003] Currently, 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 corrosion, and easy degradation, which affects the absorption performance of the absorbent and increases the operating cost of the device. Since the absorption process of the absorbent for CO2 is an acid-base reaction, the reaction kinetics is slow, and the introduction of a catalyst to enhance the absorption effect of the absorbent for CO2 becomes a high-efficiency and energy-saving solution. The catalyst can increase the mass transfer interface area in physics, and provide a reaction path with lower activation energy in chemistry to speed up the chemical absorption process of CO2.

[0004] Chinese patent CN113332855A discloses a packing absorption tower for organic amine carbon dioxide capture and a carbon capture absorption system, which comprises an absorption tower shell. A lean liquid nozzle, a plurality of packing layers and a slurry pool are sequentially arranged in the absorption tower shell from top to bottom. The active components in the catalytic layer between adjacent packing layers are one or more of K ions, Na ions and Mg ions. The absorption tower and system can accelerate the absorption speed of CO2, but still have problems of small absorption capacity and low capture rate. Therefore, in order to further accelerate the absorption rate of CO2 and improve the absorption performance of the absorbent, thereby reducing the cost of CO2 capture, a low-concentration CO2 catalytic absorption method is developed, which has good industrial application prospects. SUMMARY

[0005] The present application aims at 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 application thereof, wherein a Lewis base catalyst with high catalytic activity is prepared, and the Lewis base catalyst is combined with an organic amine solvent to absorb low-concentration CO2, so as to accelerate the absorption rate of CO2 and improve the capture rate and absorption capacity of CO2.

[0006] To solve the above technical problems, the present application provides a low-concentration CO2 catalytic absorption method in the first aspect, 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 in S1, making flue gas react with the organic amine solvent provided in S2.

[0010] According to some embodiments of the present application, 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, nutshell-based activated carbon, wood-based activated carbon and coal-based activated carbon; preferably, the carrier is coconut shell-based activated carbon.

[0012] According to some embodiments of the present application, 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 application have unsaturated coordinated O 2- , which can provide rich electrons as Lewis basic sites, and strengthen the absorption effect of the absorbent on CO2; but the alkaline earth metal oxides are easy to dissolve in long-time operation, and can be loaded on the carrier to improve the stability and the dispersity of the metal oxides; activated carbon is a kind 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 carrier of a catalyst, so that the activated carbon can be used as a carrier to load different alkaline earth metal oxides MgO, CaO or BaO on the surface thereof to prepare a Lewis base catalyst, and improve the service life and activity of the catalyst.

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

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

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

[0017] According to some embodiments of the present application, in S2, the organic amine solvent is an aqueous organic amine solution; and / or, in the organic amine solvent, the total amine concentration is 2mol / L~7mol / L, preferably 3mol / L~6mol / L, for example 3mol / L, 4mol / L, 5mol / L, 6mol / L. In the present application, the total amine concentration is the ratio of the sum of the amounts of substances of each organic amine in the aqueous organic amine solution to the volume of the aqueous organic amine solution, i.e. total amine concentration = sum of amounts of substances of each organic amine / aqueous organic amine solution volume.

[0018] According to some embodiments of the present application, 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%~35%, preferably 10%~25%, for example 15%.

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

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

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

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

[0023] Advantages:

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

[0025] The catalytic absorption method of low-concentration CO2 solves the problems of low absorption rate, small absorption capacity, and low capture rate when using the organic amine solvent alone to absorb CO2. In addition, the Lewis base catalyst with low cost, high catalytic activity, and repeated use is used in the present application, and the Lewis base catalyst is combined with the organic amine solvent to absorb CO2, which can effectively improve the absorption capacity and capture rate of CO2 and speed up the absorption rate of CO2, thereby reducing the investment cost of the CO2 absorption system. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 It is a flowchart of the CO2 catalytic absorption reaction of the present application.

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

[0028] The present application will be further described below in conjunction with examples. However, the present application is not limited by these examples.

[0029] In the present application, the absorption capacity of CO2 (mol / mol) is the ratio of the amount of substance of CO2 to the sum of the amount of substance of each organic amine in the organic amine solvent, which is calculated by measuring the mass change of the four flasks before and after CO2 absorption or acid-base titration analysis. The CO2 absorption rate is the ratio of the change of CO2 absorption capacity to time within 10 min before the reaction. 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 inlet simulated flue gas, %;

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

[0034] In the present application, the infrared CO2 gas analyzer is purchased from Beijing Huanyun Instrument Company, the model number is GHX-3010E1, and the range is 0-20%.

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

[0036] In the present application, the monoethanolamine is purchased from Aladdin Reagent Co., Ltd., and the specification is analytical pure.

[0037] In the present application, the piperazine is purchased from Aladdin Reagent Co., Ltd., and the specification is analytical pure.

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

[0039] Example 1

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

[0041] An organic amine aqueous solution MEA-PZ with a total amine concentration of 6 mol / L is prepared, in which the molar ratio of MEA to PZ is 4:1, and the organic amine aqueous solution is added to a four-necked flask; (simulated flue gas) N2 and CO2 are mixed and then introduced into the four-necked flask by controlling the reaction temperature at 40℃ through a water bath, and the CO2 volume fraction in the mixed gas is controlled at 15% by a mass flow meter; the mixed gas discharged after the reaction is condensed by a spiral condenser and then vented, and the outlet CO2 concentration is determined by an infrared CO2 gas analyzer; the organic amine solvent absorption CO2 reaction is terminated after 4 h; the organic amine aqueous solution after the reaction is sampled to detect the CO2 absorption capacity, absorption rate and capture rate, and the results are shown in Table 2.

[0042] Example 2

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

[0044] (1) Preparation of Lewis base catalyst

[0045] Dissolve 57.6 g of Mg(N03)2-6H20 in 40 mL of deionized water, then add 30 g of coconut shell-based activated carbon, stir and soak for 10 h, and then air dry overnight, and then dry at a temperature of 110°C for 6 h; place the dried sample in a muffle furnace and calcine at a temperature of 600°C for 5 h to obtain a Lewis base catalyst MgO-AC, wherein the mass fraction of MgO is 30 wt%. Analyze the pore structure characteristics of the Lewis base catalyst MgO-AC by the N2 adsorption method, and the results are shown in Table 1. Figure 2 and Table 1.

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

[0047] Prepare 400 mL of an aqueous organic amine solution MEA-PZ with a total amine concentration of 6 mol / L, wherein the molar ratio of MEA to PZ is 4:1, and add the aqueous organic amine solution to a four-necked flask, and add 31.68 g of the above Lewis base catalyst MgO-AC (the amount of Lewis base catalyst added accounts for 20 wt% of the aqueous organic amine solution); control the reaction temperature at 40°C by water bath, pass the mixed gas of N2 and CO2 (simulated flue gas) into the four-necked flask, and control the volume fraction of CO2 in the mixed gas to be 15% by mass flow meter; after the reaction, the mixed gas discharged after condensation by a spiral condenser is vented, and the outlet CO2 concentration is determined by an infrared CO2 gas analyzer; the catalytic organic amine solvent absorption of CO2 reaction is terminated after 4 h; sample the aqueous organic amine solution after the reaction 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] Comparative Example 1 differs from Example 2 in 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, and the statistical absorption results are shown in Table 2.

[0050] Comparative Example 2

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

[0052] Example 3

[0053] This example provides a method for catalytic absorption of low-concentration CO2.

[0054] (1) Preparation of Lewis base catalyst

[0055] Dissolve 37.92 g of Ca(NO3)2·4H2O in 40 mL of deionized water, then add 30 g of coconut shell-based activated carbon, stir and impregnate for 10 h, then air dry overnight, and then dry at a temperature of 110°C for 6 h. Place the dried sample in a muffle furnace and calcine at a temperature of 600°C for 5 h to obtain a Lewis base catalyst CaO-AC, wherein the mass fraction of CaO is 30 wt%. Analyze the pore structure characteristics of the Lewis base catalyst CaO-AC by N2 adsorption method, and the results are shown in Table 1. Figure 2 and Table 1.

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

[0057] Prepare 400 mL of an organic amine aqueous solution MEA-PZ with a total amine concentration of 6 mol / L, wherein the molar ratio of MEA to PZ is 4:1. Add the organic amine aqueous solution to a four-necked flask, and add 31.68 g of the Lewis base catalyst CaO-AC (the amount of Lewis base catalyst added accounts for 20 wt% of the organic amine aqueous solution). Control the reaction temperature at 40°C by water bath, pass the mixed gas of N2 and CO2 (simulated flue gas) into the four-necked flask, and control the volume fraction of CO2 in the mixed gas to be 15% by mass flow meter. The mixed gas discharged after the reaction is condensed by a spiral condenser and vented, and the outlet CO2 concentration is determined by an infrared CO2 gas analyzer. The reaction is terminated after 4 h of catalytic absorption of CO2 by the organic amine solvent. Sample the organic amine aqueous solution after the reaction 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] Comparative Example 3 differs from Example 3 in that 31.68 g of CaO is added instead of the Lewis base catalyst CaO-AC in step (2), and the other conditions remain unchanged. The statistical absorption results are shown in Table 2.

[0060] Example 4

[0061] This example provides a method for catalytic absorption of low-concentration CO2.

[0062] (1) Preparation of Lewis base catalyst

[0063] Dissolve 15.33 g of Ba(NO3)2 in 40 mL of deionized water, then add 30 g of coconut shell-based activated carbon, stir and impregnate for 10 h, then air dry overnight, and then dry at a temperature of 110°C for 6 h. Place the dried sample in a muffle furnace and calcine at a temperature of 600°C for 5 h to obtain a Lewis base catalyst BaO-AC, wherein the mass fraction of BaO is 30 wt%. Analyze the pore structure characteristics of the Lewis base catalyst BaO-AC by N2 adsorption method, and the results are shown in Table 1. Figure 2 and Table 1.

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

[0065] Prepare 400 mL of an organic amine aqueous solution (MEA-PZ) with a total amine concentration of 6 mol / L, where the molar ratio of MEA to PZ is 4:1. Add the organic amine aqueous solution to a four-necked flask, and add 1.68 g of the Lewis base catalyst BaO-AC3 (the amount of Lewis base catalyst added accounts for 20 wt% of the organic amine aqueous solution). Control the reaction temperature at 40 °C using a water bath. Mix N2 and CO2 (simulated flue gas) and introduce them into the four-necked flask, controlling the volume fraction of CO2 in the mixture to 15% using a mass flow meter. After the reaction, condense the mixed gas through a spiral condenser and release it into the atmosphere. Measure the outlet CO2 concentration using an infrared CO2 gas analyzer. Terminate the reaction after 4 h of catalytic organic amine solvent absorption of CO2. Samples of the organic amine aqueous solution after the reaction were taken to detect the CO2 absorption capacity, absorption rate, and capture rate. The 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), 31.68g of BaO was added to replace the Lewis base catalyst BaO-AC, while other conditions remained unchanged. The statistical absorption results are shown in Table 2.

[0068] Table 1

[0069]

[0070] As shown in Table 1, the specific surface area, total pore volume, and average pore size of the Lewis base catalysts prepared by supporting alkaline earth metal oxides on coconut shell activated carbon in Examples 2-4 are all lower than those of coconut shell activated carbon, indicating that the active components can block part of the pore structure of the activated carbon. In addition, the specific surface area, total pore volume, and average pore size 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, respectively, indicating that the Lewis base catalyst MgO-AC has a more developed porous structure.

[0071] Furthermore, the N2 adsorption-desorption isotherms of the Lewis base catalysts MgO-AC, CaO-AC, and BaO-AC prepared in Examples 2-4 of this invention are shown below. 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 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, the CO2 absorption capacity of Example 1 is 0.67 mol / mol, the CO2 absorption rate is 4.35 mmol / mol·min, and the CO2 capture rate is 81.58% in the presence of the organic amine solvent only, indicating that the use of the organic amine solvent alone has a general effect on CO2 absorption. The CO2 absorption capacity, absorption rate, and capture rate are increased in the presence of a single coconut shell-based activated carbon (AC) or alkaline earth metal oxide (MgO, CaO, BaO) as a catalyst in Comparative Examples 1 to 4. The CO2 absorption capacity and capture rate are significantly improved, and the CO2 absorption rate is accelerated in Examples 2 to 4 in which a Lewis base catalyst (MgO-AC, CaO-AC, BaO-AC) is added to the organic amine solvent, indicating that the catalytic performance of the Lewis base catalyst prepared in Examples 2 to 4 is superior to that of a single catalyst. In particular, the CO2 absorption capacity is increased by 18%, the CO2 absorption rate is increased by 43%, and the CO2 capture rate is increased by 16% in Example 2 in which the Lewis base catalyst (MgO-AC) is added to the organic amine solvent.

[0075] In the above, the Lewis base catalyst prepared in Examples 2 to 4 has excellent electron-donating ability, a porous surface structure, and a large specific surface area, and thus exhibits excellent catalytic activity, which is helpful to improve the CO2 absorption process and promote the formation of carbamate and bicarbonate products.

[0076] Examples 5 to 6

[0077] Examples 5 to 6 differ from Example 2 in that different amounts of MgO-AC catalyst are used. Specifically, the amount of MgO-AC catalyst is used as a variable, and the amount of MgO-AC catalyst added to the catalytic absorption system is 10 wt% and 15 wt% of the organic amine solvent, respectively, and the other conditions are not changed. The statistical results are shown in Table 3.

[0078] Table 3

[0079] Example Example 5 Example 6 MgO-AC catalyst loading (wt%) 10 15 CO2absorption capacity (mol / mol) 0.71 0.74 CO2absorption rate (mmol / mol min) 5.94 6.03 CO2 capture rate (%) 90.85 91.57

[0080] From Table 3, it can be seen that when the amount of MgO-AC catalyst is in the range of 10wt%-15wt%, the CO2 absorption capacity can reach 0.71mol / mol-0.74mol / mol, the CO2 absorption rate can reach 5.94mmol / mol·min-6.03mmol / mol·min, and the CO2 capture rate can reach 90.85%-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, and thus improve the absorption rate, absorption capacity and capture rate of the organic amine solvent for CO2.

[0081] Examples 7-9

[0082] Examples 7-9 differ from Example 2 in that different concentrations of aqueous organic amine MEA-PZ are used. Specifically, the total amine concentration of the organic amine solvent MEA-PZ is used as a variable, and the total amine concentration of the organic amine solvent MEA-PZ in the catalytic absorption system is set to 3mol / L, 4mol / L and 5mol / L, respectively, and other conditions remain unchanged. The effect of the total amine concentration on the 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 CO2absorption capacity (mol / mol) 0.69 0.72 0.75 CO2absorption rate (mmol / mol min) 4.85 5.56 6.07 CO2 capture rate (%) 89.74 91.37 92.24

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

[0086] Examples 10-11

[0087] Examples 10-12 differ from Example 2 in 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, 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 Example 11 MEA to PZ molar ratio 2：1 3：1 CO2absorption capacity (mol / mol) 0.72 0.75 CO2absorption rate (mmol / mol min) 5.74 5.98 CO2 capture rate (%) 91.15 92.74

[0090] From Table 5, it can be seen 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%; thus, it is shown that the organic amine solvent MEA-PZ has good absorption effect on low-concentration CO2 and has high CO2 capture rate in the molar ratio range.

[0091] Examples 12-19

[0092] Examples 12-16 differ from Example 2 in 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 set as a variable for experiments, and the volume fraction of CO2 in the simulated flue gas is set to be 2%, 5%, 10%, 20%, 25%, 30%, 35%, and 40%, respectively, and other experimental conditions remain unchanged, and the effects of the volume fraction of CO2 in the simulated flue gas on the CO2 absorption capacity, absorption rate, and capture rate are shown in Table 6.

[0093] Table 6

[0094]

[0095] From Table 6, it can be seen 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 0.63 mol / mol to 0.83 mol / mol, the absorption rate of CO2 can reach 5.57 mmol / mol·min to 6.63 mmol / mol·min, and the CO2 capture rate can reach 89.73% to 96.11%; this shows that the organic amine solvent MEA-PZ has good absorption performance on CO2 in a wide range of CO2 volume fraction (5% to 35%), has large absorption capacity, absorption rate, and capture rate; in addition, when the volume fraction of CO2 is less than 5% or higher than 35%, the absorption performance of the organic amine solvent MEA-PZ on CO2 is lower.

[0096] It should be noted that the foregoing examples have been provided merely for the purposes of illustration and are not intended to limit the application in any way. Descriptions and examples of materials and processes of the application are intended to be illustrative not limiting. Any modifications of the application and other applications of the application will occur to those skilled in the art to which the application pertains and many options for modification of the application will suggest themselves. The application lies in the broadest aspects of the technological concepts involved. Descriptions and examples of specific chemical materials and processes are intended to be illustrative of the application and it is intended that requests for patent protection be limited to one of the specific embodiments described above, described in the following claims, and any equivalents thereof.

Claims

1. A method for catalytic absorption of low concentrations of CO2, characterized in that, The method comprises the following steps: S1, providing a supported catalyst; the supported catalyst comprises a carrier and an active component; the active component is an alkaline earth metal oxide; the carrier is selected from at least one of coconut shell-based activated carbon, nutshell-based activated carbon, wood-based activated carbon and coal-based activated carbon; S2, providing an organic amine solvent; S3, reacting flue gas with the organic amine solvent provided in S2 under the action of the supported catalyst provided in S1; In S3, the supported catalyst is added in an amount of 10wt%-20wt% of the organic amine solvent. The volume fraction of CO2 in the flue gas is 10%-25%.

2. The low-concentration CO2 catalytic absorption method according to claim 1, characterized by, In S1, the supported catalyst is a Lewis base catalyst. And / or, the alkaline earth metal oxide is selected from at least one of MgO, CaO and BaO.

3. The low-concentration CO2 catalytic absorption method according to claim 2, characterized by, The precursor of the alkaline earth metal oxide is selected from at least one of Mg(NO3)2·6H2O, Ca(NO3)2·4H2O and Ba(NO3)2.

4. The low-concentration CO2 catalytic absorption method according to any one of claims 1 to 3, characterized by, In S1, the mass fraction of the active component in the supported catalyst is 15wt%-35wt%.

5. The low-concentration CO2 catalytic absorption method according to claim 4, characterized by, In S1, the mass fraction of the active component in the supported catalyst is 15wt%-25wt%.

6. The low-concentration CO2 catalytic absorption method according to any one of claims 1 to 3, characterized by, In S2, the organic amine solvent comprises at least two organic amines.

7. The low-concentration CO2 catalytic absorption method according to claim 6, characterized by, The organic amine is selected from monoethanolamine, diethanolamine, triethanolamine, diisopropanolamine, N-methyl-diethanolamine, 2-amino-2-methyl-1-propanol and piperazine.

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

9. The low-concentration CO2 catalytic absorption method according to claim 8, characterized by, In the organic amine solvent, the total amine concentration is 3mol / L-6mol / L.

10. The low-concentration CO2 catalytic absorption method according to any one of claims 1 to 3, characterized by, In S3, the flue gas is a mixture of N2 and CO2.

11. The low-concentration CO2 catalytic absorption method according to any one of claims 1 to 3, characterized by, In S3, the reaction conditions include: a temperature of 20°C-55°C; and a time of 1h-6h.

12. The method of claim 11, wherein the low concentration CO2 catalytic absorption process is characterized by, In S3, the reaction conditions include: a temperature of 30°C-45°C; and a time of 1h-4h.

13. Use of the low-concentration CO2 catalytic absorption method according to any one of claims 1-12 in carbon capture.

14. Use of the low-concentration CO2 catalytic absorption method according to any one of claims 1-12 in flue gas of coal combustion or gas combustion.

Images