A co2 complex capture system and a method of capturing co2

Abstract

The application belongs to the technical field of CO2 desorption and relates to a CO2 composite capture system and a method for capturing CO2.The CO2 composite capture system comprises a ZrO2 / MCM-41 catalyst, the ZrO2 / MCM-41 catalyst comprises a MCM-41 molecular sieve carrier and ZrO2 loaded on the MCM-41 molecular sieve carrier, and further comprises a composite amine absorbent, the composite amine absorbent comprises 3-7 parts of piperazine, 3-7 parts of N-methyldiethanolamine and 20-40 parts of a third amine component by weight, and the third amine component is diethylenetriamine or hexamethylenediamine.The total desorption amount of the CO2 composite capture system is increased by about 24.7%, and the relative heat load is reduced to 18.5%, so that the CO2 desorption amount is higher and the desorption heat load is lower.

Description

Technical Field

[0001] This invention belongs to the field of CO2 desorption technology, and relates to a CO2 composite capture system and a method for capturing CO2. Background Technology

[0002] Among CO2 capture technologies, chemical absorption based on organic amine solutions has become the most widely used post-combustion CO2 capture technology in industry due to its high capture efficiency and applicability to low partial pressure flue gas conditions. However, this technology has long faced a core bottleneck: the energy consumption of the CO2-rich amine solution regeneration process is too high, typically accounting for more than 60% of the total operating cost of the CO2 capture process. This energy consumption problem severely restricts the economic feasibility and large-scale application of amine-based CO2 capture technology.

[0003] To reduce the energy consumption of amine liquid regeneration, researchers have carried out extensive work in two main directions: first, developing novel composite amine absorbent formulations to improve the overall absorption-desorption performance of amine liquid; and second, introducing solid acid catalysts to promote the release of CO2 from amine-rich liquid through catalysis, thereby reducing desorption temperature and energy consumption.

[0004] Regarding catalysts, existing research has shown that SO4 is supported on MCM-41 molecular sieves. 2- ZrO2 solid superacid catalyst is used for the CO2 desorption process of amine liquid. Based on this, Hunan University has disclosed a Fe2O3 / ZrO2 / SO4 catalyst. 2- -MCM-41 composite molecular sieve catalyst (CN109453801A), through the modification of Fe2O3 into the ultra-strong solid acid ZrO2 / SO4 2- Supported on MCM-41, this catalyst is used for the catalytic desorption of CO2-rich amine solutions. China Datang Corporation Technology Innovation Co., Ltd. has proposed a bimetallic catalyst (CN202511513776) to promote the CO2 absorption-desorption cycle in alkanolamine solutions. Using MCM-41 as the support, it simultaneously supports Zr-based and Cu-based compounds as bimetallic active components. This catalyst can increase the desorption capacity by 21% and reduce the relative heat load by approximately 26% in 30% MEA solution. However, the above catalysts are mainly designed for traditional MEA monoamine systems or water-deficient amine solutions, and all employ secondary metal components such as Fe and Cu, or SO4. 2- The catalyst composition is relatively complex due to the modification with acidic groups.

[0005] Regarding compound amine absorbents, existing technologies have disclosed various ternary compound organic amine formulations. For example, an anhydrous CO2 absorbent ternary compound organic amine agent (CN109758871A) uses DETA combined with MDEA or PZ. However, its technical solution is an anhydrous system, which differs significantly from the aqueous amine liquid system commonly used in industry, limiting its industrial applicability. An existing technology entitled "An Organic Amine Compound Absorbent for Removing CO2 from Coal-fired Flue Gas" (CN103394277A) lists DETA, MDEA, and PZ as usable components. However, this existing technology still has relatively high desorption energy consumption. Summary of the Invention

[0006] The purpose of this invention is to provide a CO2 composite capture system and a method for capturing CO2 that improves the CO2 desorption rate.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A CO2 composite capture system includes a ZrO2 / MCM-41 catalyst, wherein the ZrO2 / MCM-41 catalyst comprises an MCM-41 molecular sieve support and ZrO2 supported on the MCM-41 molecular sieve support. And a complex amine absorbent, which, by weight, comprises 3-7 parts piperazine, 3-7 parts N-methyldiethanolamine and 20-40 parts a third amine component, wherein the third amine component is diethylenetriamine or hexamethylenediamine.

[0008] According to embodiments of the present invention, the present invention can be further optimized, and the optimized technical solution is as follows: In one preferred embodiment, the mass-to-volume ratio of the ZrO2 / MCM-41 catalyst to the composite amine absorbent is 1-20 g / L; preferably 5-15 g / L; and more preferably 10-15 g / L.

[0009] In one preferred embodiment, the composite amine absorbent further includes a solvent.

[0010] In one preferred embodiment, the solvent is water.

[0011] In one preferred embodiment, the composite amine absorbent comprises 3-7 parts piperazine, 3-7 parts N-methyldiethanolamine, 20-40 parts a third amine component, and 40-60 parts a solvent.

[0012] In one preferred embodiment, the composite amine absorbent comprises, by weight, 3-7 parts piperazine, 3-7 parts N-methyldiethanolamine, and 20-30 parts diethylenetriamine.

[0013] In one preferred embodiment, the composite amine absorbent comprises, by weight, 3-7 parts piperazine, 3-7 parts N-methyldiethanolamine and 20-35 parts diethylenetriamine.

[0014] In one preferred embodiment, the composite amine absorbent comprises, by weight, 3-7 parts piperazine, 3-7 parts N-methyldiethanolamine, and 25-35 parts diethylenetriamine.

[0015] In one preferred embodiment, the composite amine absorbent comprises, by weight, 3-7 parts piperazine, 3-7 parts N-methyldiethanolamine and 25-40 parts hexamethylenediamine.

[0016] In one preferred embodiment, the composite amine absorbent comprises, by weight, 3-7 parts piperazine, 3-7 parts N-methyldiethanolamine and 25-35 parts hexamethylenediamine.

[0017] In one preferred embodiment, the composite amine absorbent comprises, by weight, 3-7 parts piperazine, 3-7 parts N-methyldiethanolamine and 25-30 parts hexamethylenediamine.

[0018] In one preferred embodiment, the composite amine absorbent comprises, by weight, 3-7 parts piperazine, 3-7 parts N-methyldiethanolamine and 30-35 parts hexamethylenediamine.

[0019] In one preferred embodiment, the ZrO2 / MCM-41 catalyst is a powdered solid catalyst.

[0020] In one preferred embodiment, the method for preparing the ZrO2 / MCM-41 catalyst includes the following steps: Disperse the MCM-41 molecular sieve and adjust the pH to 9-10 to obtain a suspension; The zirconium precursor solution was added dropwise to the suspension, and stirring was continued after the addition was complete. After the reaction was completed, the product was collected, washed, dried, and calcined to obtain the ZrO2 / MCM-41 catalyst.

[0021] In one preferred embodiment, the zirconium precursor solution is one or more of ZrCl4, ZrOCl2, and Zr(NO3)4.

[0022] In one preferred embodiment, the concentration of the zirconium precursor solution is 1-5 g / 100 mL.

[0023] In one preferred embodiment, the reaction time is 2-8 hours.

[0024] In one preferred embodiment, the concentration of the suspension is 5-15 g / 100 mL.

[0025] In one preferred embodiment, the calcination temperature is 500-800℃, the time is 1-4h, and the heating rate is 1-4℃ / min.

[0026] Based on the same inventive concept, this invention also claims protection for the application of the CO2 composite capture system in the amine-based CO2 capture process.

[0027] In one preferred embodiment, the desorption temperature during the trapping process is 60-120°C; more preferably 70-95°C.

[0028] In one preferred embodiment, the ZrO2 / MCM-41 catalyst is added to the composite amine absorbent, stirred evenly, and then used for desorption.

[0029] Based on the same inventive concept, this invention also claims a method for capturing CO2, comprising the following steps: S1. The composite amine absorbent absorbs CO2 to a predetermined load to obtain a CO2-rich composite amine absorbent solution. S2. Add the ZrO2 / MCM-41 catalyst to the CO2-rich composite amine absorption solution to obtain the desorption solution; S3. Desorb the desorbent solution by heating.

[0030] In one preferred embodiment, in S1, the composite amine absorbent absorbs CO2 from the flue gas to a predetermined load to obtain a CO2-rich composite amine absorbent liquid.

[0031] In one preferred embodiment, in S1, the composite amine absorbent is saturated with CO2.

[0032] In one preferred embodiment, the temperature for heating and desorption is 60-120°C; more preferably 70-95°C.

[0033] Compared with the prior art, the beneficial effects of the present invention are: This invention utilizes the ZrO2 / MCM-41 catalyst in the desorption process of CO2-rich amine solutions using a preferred composite amine absorbent, further enhancing the CO2 desorption performance of the composite amine absorbent, which already possesses good desorption capabilities. Specifically, in the 5PZ+30DETA+5MDEA system, the addition of the ZrO2 / MCM-41 catalyst increases the total desorption capacity by approximately 24.7% and reduces the relative heat load to 18.5%, exhibiting higher CO2 desorption capacity and lower desorption heat load. In the 5PZ+25HMDA+5MDEA system, the addition of the ZrO2 / MCM-41 catalyst increases the maximum desorption rate by approximately 31.4% and reduces the relative heat load by approximately 26.0%, exhibiting a faster CO2 desorption rate. This demonstrates that the ZrO2 / MCM-41 catalyst, used in conjunction with a preferred composite amine system, can further enhance the desorption performance of CO2-rich amine solutions, making it suitable for rich-liquid desorption and regeneration in amine-based CO2 capture processes. Attached Figure Description

[0034] Figure 1 The image shows the XRD pattern of the ZrO2 / MCM-41 catalyst in Example 1.

[0035] Figure 2 The image shows the BET plot of the ZrO2 / MCM-41 catalyst in Example 1.

[0036] Figure 3 The SEM-EDS characterization results of the ZrO2 / MCM-41 catalyst in Example 1 are shown below. (a) is the SEM morphology of the catalyst, (b) is the EDS surface distribution of Zr, (c) is the EDS surface distribution of Si, and (d) is the EDS surface distribution of O.

[0037] Figure 4 This is a schematic diagram of a CO2 desorption performance testing device. Detailed Implementation

[0038] This invention is not limited to the specific embodiments listed below. Those skilled in the art can implement this invention using various other specific embodiments based on the content disclosed herein. Any modifications or alterations made to the design structure and concept of this invention fall within the protection scope of this invention. It should be noted that, unless otherwise specified, the embodiments and features described in this invention can be combined with each other.

[0039] Example 1 Preparation of ZrO2 / MCM-41 catalyst: 10g of MCM-41 molecular sieve was dispersed in 100mL of deionized water. Ammonia was added under magnetic stirring to adjust the pH of the suspension to 9-10, and stirring was continued at room temperature for 30min to obtain an MCM-41 suspension. 4g of ZrCl4 was dissolved in 50mL of deionized water to obtain a zirconium precursor solution. The zirconium precursor solution was slowly added dropwise to the MCM-41 suspension under magnetic stirring. After the addition was complete, stirring was continued at room temperature for 4h. After the reaction was completed, the solid product was collected by vacuum filtration and washed with deionized water until the pH of the filtrate was neutral. The obtained solid was vacuum dried at 80℃ for 12h, then placed in an air atmosphere and heated to 550℃ at a heating rate of 2℃ / min for 2h. After cooling to room temperature, a ZrO2 / MCM-41 catalyst was obtained.

[0040] CO2 desorption performance test method: like Figure 4 As shown, 100 mL of CO2-rich amine solution was placed in a three-necked flask. Depending on the specific examples or comparative examples, 1.0 g of the ZrO2 / MCM-41 catalyst prepared in Example 1 was added or not added. All CO2-rich amine solutions were pre-saturated with CO2 to ensure that each amine system was at its maximum CO2 loading. When adding the catalyst, the catalyst dosage was 10 g / L of CO2-rich amine solution. The oil bath temperature was adjusted to 90°C, and magnetic stirring was turned on. Before the experiment, N2 was purged at a flow rate of 300 mL / min to remove any CO2 present in the pipeline. During the subsequent desorption process, N2 was continuously introduced as a carrier gas. The carrier gas mixed with the desorbed CO2 and then entered the CO2 analyzer for measurement. The experiment included a heating phase and an isothermal phase, with a desorption time of 50 min. The heating phase was used to gradually increase the amine solution temperature from the initial temperature to the preset temperature of 90°C, while the isothermal phase maintained a constant temperature of 90°C. Throughout the desorption phase, the signal detected by the CO2 analyzer showed a trend of first rising and then falling. Based on the data recorded by the CO2 analyzer, the total CO2 desorption amount, the desorption amount in the first 750 seconds, and the maximum desorption rate were calculated; the relative heat load was calculated based on the relationship between the input heat and the amount of CO2 desorbed during the desorption process. After the desorption experiment, the amine liquid system containing the catalyst was centrifuged to recover the solid catalyst and collect the supernatant.

[0041] The CO2 desorption rate and relative heat load were determined using the following methods: The CO2 desorption rate is calculated based on the CO2 concentration and carrier gas flow rate detected in real time by the CO2 analyzer. The CO2 desorption rate at each time point during the desorption process is denoted as... r The amount of CO2 desorbed in the gas phase is obtained by integrating the change in desorption rate over time, as shown in the following formula: (1) In the formula, n CO2 desorption amount, in mol; r The desorption rate of CO2 is expressed in mol / s. t Let be the desorption time, in seconds.

[0042] The heat load from CO2 desorption was estimated using a heat transfer model. The steady-state heat transferred from the oil bath to the amine solution in the flask was calculated using the Fourier heat transfer equation. (2) In the formula, q The steady-state heat transfer rate is J / s; k is the thermal conductivity, W / (m·K); and A is the heat transfer area, m². 2 ; dT Let K be the temperature difference between the oil bath and the inner wall of the flask. dx Let be the flask wall thickness, in meters (m).

[0043] The heat load per unit of CO2 desorption is calculated using the following formula: (3) In the formula, Q q is the CO2 desorption heat load, J / mol; q is the steady-state heat transfer rate, J / s; r is the CO2 desorption rate, mol / s.

[0044] To facilitate comparison of desorption energy consumption in different amine systems and catalytic systems, a relative heat load is introduced, and the calculation formula is as follows: (4) In the formula, R This refers to the relative heat load. Q sample The heat load for CO2 desorption in the amine system or catalytic amine system to be tested; Q MEA This represents the heat load for CO2 desorption in a saturated MEA system. A lower relative heat load indicates a lower heat load required for CO2 desorption under the same evaluation conditions.

[0045] Example 2 Catalytic desorption of the 5PZ+30DETA+5MDEA complex amine system: A 5PZ + 30DETA + 5MDEA composite amine absorbent was prepared, comprising, by mass percentage, 5% piperazine (PZ), 30% diethylenetriamine (DETA), 5% N-methyldiethanolamine (MDEA), and the remainder being water. The composite amine absorbent was used to absorb CO2 until saturation, yielding a CO2-rich composite amine absorbent solution. 100 mL of the CO2-rich composite amine absorbent solution was taken, and 1.0 g of the ZrO2 / MCM-41 catalyst prepared in Example 1 was added. A desorption experiment was conducted according to the CO2 desorption performance testing method described above, and the total CO2 desorption amount, the desorption amount in the first 750 seconds, the maximum desorption rate, and the relative heat load were recorded.

[0046] Example 3 Catalytic desorption of the 5PZ+25HMDA+5MDEA complex amine system: A 5PZ + 25HMDA + 5MDEA composite amine absorbent was prepared, comprising, by mass percentage, 5% PZ, 25% hexamethylenediamine (HMDA), 5% MDEA, and the remainder being water. The composite amine absorbent was used to absorb CO2 until saturation, yielding a CO2-rich composite amine absorbent solution. 100 mL of the CO2-rich composite amine absorbent solution was taken, and 1.0 g of the ZrO2 / MCM-41 catalyst prepared in Example 1 was added. A desorption experiment was conducted according to the CO2 desorption performance testing method described above, and the total CO2 desorption amount, the desorption amount in the first 750 seconds, the maximum desorption rate, and the relative heat load were recorded.

[0047] Comparative Example 1 Desorption in saturated MEA systems: CO2 was absorbed to saturation using 5M MEA (30.2% by mass) to obtain a saturated MEA-rich solution. Desorption experiments were conducted without the addition of a catalyst, following the CO2 desorption performance testing method described above. The total CO2 desorption amount, the desorption amount in the first 750 seconds, the maximum desorption rate, and the relative heat load were recorded.

[0048] Comparative Example 2 Catalytic desorption of saturated MEA systems: Comparative Example 1 was repeated, except that 1.0 g of the ZrO2 / MCM-41 catalyst prepared in Example 1 was added.

[0049] Comparative Example 3 Catalyst-free desorption of the 5PZ+30DETA+5MDEA complex amine system: Repeat Experiment 2, except that no catalyst was added.

[0050] Comparative Example 4 Catalyst-free desorption of the 5PZ+25HMDA+5MDEA complex amine system: Repeat Example 3, except that no catalyst is added.

[0051] The CO2 desorption performance results of the composite amine systems in Comparative Examples 2-3 and Comparative Examples 1-4 are shown in Table 1.

[0052] Table 1. Comparison of desorption performance of the complex amine systems in Examples 2-3 and Comparative Examples 1-4 The relative heat loads in Table 1 are relative to the relative heat loads in Comparative Example 1.

[0053] As shown in Table 1, compared with the saturated MEA system of Comparative Example 1, the 5PZ+30DETA+5MDEA composite amine system of Comparative Example 3 and the 5PZ+25HMDA+5MDEA composite amine system of Comparative Example 4 both exhibited higher CO2 desorption capacity and desorption rate, while the relative heat load was significantly reduced. This indicates that both composite amine absorbents have better CO2 desorption and regeneration performance than the traditional MEA system.

[0054] Compared to Comparative Example 3, in Example 2, after adding ZrO2 / MCM-41 catalyst to the 5PZ+30DETA+5MDEA composite amine system, the total desorption capacity increased from 89.42 mmol to 111.52 mmol, an increase of approximately 24.7%; the 750s desorption capacity increased from 55.40 mmol to 75.72 mmol; and the maximum desorption rate increased from 11.6 × 10⁻⁶. -5 The mol / s increased to 12.4 × 10⁻⁶. -5 The relative heat load decreased from 25.2% to 18.5%. Compared with Comparative Example 4, in Example 3, after adding ZrO2 / MCM-41 catalyst to the 5PZ+25HMDA+5MDEA composite amine system, the desorption capacity at 750s increased from 33.35 mmol to 45.12 mmol, and the maximum desorption rate increased from 10.5 × 10⁻⁶ mol / s; the relative heat load decreased from 25.2% to 18.5%. -5 The mol / s increased to 13.8 × 10⁻⁶. -5 The CO2 desorption capacity increased by approximately 31.4% from mol / s; the relative heat load decreased from 41.9% to 31.0%. This indicates that the ZrO2 / MCM-41 catalyst can further improve the CO2 desorption capacity of the composite amine system and reduce the desorption heat load.

[0055] Example 4 Based on Example 2, the amount of ZrO2 / MCM-41 catalyst added was adjusted to 5 g / L.

[0056] Example 5 Based on Example 2, the amount of ZrO2 / MCM-41 catalyst added was adjusted to 15 g / L.

[0057] Example 6 Based on Example 2, the amounts of PZ, DETA, and MDEA were adjusted to 3%, 30%, and 7%, respectively.

[0058] Example 7 Based on Example 2, the amounts of PZ, DETA, and MDEA were adjusted to 5%, 25%, and 5%, respectively.

[0059] The CO2 desorption performance of the composite amine systems in Examples 2 and 4-7 was compared, and the results are shown in Table 2.

[0060] Table 2 Comparison of desorption performance of the complex amine systems in Examples 2 and 4-7 The relative heat loads in Table 2 are relative to the relative heat loads in Comparative Example 1.

[0061] Table 2 shows that in the 5PZ+30DETA+5MDEA composite amine system, the ZrO2 / MCM-41 catalyst maintained good CO2 desorption performance at dosages of 5-15 g / L. Among them, Example 4 showed the highest maximum desorption rate, reaching 12.7 × 10⁻⁶, when the catalyst dosage was 5 g / L. -5 The total desorption capacity of Example 5 was the highest at 15 g / L catalyst, reaching 113.40 mmol, but its 750s desorption capacity decreased to 69.05 mmol, and its relative heat load increased to 20.23%. Example 2 had the highest 750s desorption capacity of 75.72 mmol at 10 g / L catalyst, and the lowest relative heat load of 18.5%. Considering the total desorption capacity, desorption rate, and energy consumption, the optimal catalyst dosage is 5-15 g / L. After adjusting the ratio of the composite amine, Examples 6 and 7 still obtained total desorption capacities of 105.39 mmol and 104.67 mmol, respectively, indicating that within the tested ratio range, the PZ, DETA, and MDEA composite system can achieve good CO2 desorption, with the 5PZ+30DETA+5MDEA system exhibiting superior overall performance.

[0062] Comparative Example 5 Based on Example 2, the ZrO2 / MCM-41 catalyst in S2 was adjusted to blank MCM-41 without ZrO2 loading.

[0063] Comparative Example 6 Based on Example 2, the ZrO2 / MCM-41 catalyst in S2 was replaced with a catalyst ZrO2 / ZSM5 supported on another carrier. The preparation method of the ZrO2 / ZSM5 catalyst is the same as in Example 1, except that 10g of MCM-41 molecular sieve was replaced with 10g of ZSM5.

[0064] The CO2 desorption performance of the composite amine system in Comparative Example 2 and Comparative Examples 5-6 is shown in Table 3.

[0065] Table 3. Comparison of desorption performance of the complex amine systems in Example 2 and Comparative Examples 5-6 The relative heat loads in Table 3 are relative to the relative heat loads in Example 2.

[0066] As shown in Table 3, compared with Comparative Example 5 which used blank MCM-41, Example 2, using the ZrO2 / MCM-41 catalyst, saw an increase in total desorption capacity from 103.75 mmol to 111.52 mmol, an increase of approximately 7.5%; a 750s desorption capacity from 63.18 mmol to 75.72 mmol, an increase of approximately 19.8%; and a maximum desorption rate from 11.8 × 10⁻⁶ mmol / L. -5 The mol / s increased to 12.4 × 10⁻⁶. -5 The relative heat load was significantly reduced. This indicates that loading ZrO2 can improve the desorption capacity and rate of CO2-rich composite amine solutions, especially enhancing CO2 release in the initial stage of desorption and reducing the desorption heat load. Compared with Comparative Example 6, which used a ZrO2 / ZSM5 catalyst, Example 2 showed an increase of approximately 21.2% in total desorption capacity, approximately 30.3% in desorption capacity at 750 s, and approximately 4.2% in maximum desorption rate, with a significant reduction in relative heat load. This indicates that under the same ZrO2 active component and preparation conditions, MCM-41 as the support has a better catalytic desorption enhancement effect. This demonstrates that the loading of the ZrO2 active component and the selection of the MCM-41 support both contribute to improving CO2 desorption performance. The ZrO2 / MCM-41 catalyst can balance CO2 desorption capacity, desorption rate, and desorption heat load, exhibiting superior overall desorption performance.

[0067] Comparative Example 7 Based on Experiment 2, PZ was not added, but only DETA and MDEA of equal mass were added.

[0068] Comparative Example 8 Based on Experiment 2, DETA was not added, but only equal amounts of PZ and MDEA were added.

[0069] Comparative Example 9 Based on Experiment 2, without adding MDEA, only adding equal amounts of PZ and DETA.

[0070] The CO2 desorption performance of the composite amine system in Comparative Example 2 and Comparative Examples 7-9 is shown in Table 4.

[0071] Table 4. Comparison of desorption performance of the complex amine systems in Example 2 and Comparative Examples 7-9 The relative heat loads in Table 4 are relative to the relative heat loads in Example 2.

[0072] As shown in Table 4, based on the 5PZ+30DETA+5MDEA ternary complex amine system of Example 2, the CO2 desorption performance of Comparative Examples 7 and 8 decreased after removing one of the amine components. Specifically, the total desorption capacity of Comparative Example 7 decreased from 111.52 mmol to 105.80 mmol, a decrease of approximately 5.13%; the desorption capacity at 750 s decreased from 75.72 mmol to 65.56 mmol, a decrease of approximately 13.42%; and the maximum desorption rate decreased from 12.4 × 10⁻⁶ mmol / L. -5 mol / s decreased to 11.5 × 10 -5 The relative heat load increased to 115.50%. In Comparative Example 8, the total desorption capacity decreased to 103.46 mmol / s, a decrease of approximately 7.23%; the desorption capacity at 750 s decreased to 66.22 mmol, a decrease of approximately 12.55%; and the maximum desorption rate decreased to 11.7 × 10⁻⁶ mol / s. -5 The relative heat load increased to 114.36% (mol / s). This indicates that the combined use of each amine component in the ternary complex amine system is beneficial for increasing CO2 desorption capacity and desorption rate, while reducing the desorption heat load. In Comparative Example 9, using the 5PZ+5DETA system, the total desorption capacity was only 25.72 mmol, the desorption capacity at 750 s was 20.45 mmol, and the maximum desorption rate was 5.4 × 10⁻⁶ mol / s. -5 The CO2 loading and desorption capacity of the system were reduced by approximately 76.94%, 72.99%, and 56.45% compared to Example 2, respectively, while the relative heat load increased to 370.27%. This indicates that, under conditions of low total amine concentration and absence of MDEA, the CO2 loading and desorption capacity of the system were significantly insufficient. In summary, the 5PZ+30DETA+5MDEA ternary composite amine system used in Example 2 can achieve a balance between high total desorption capacity, large initial desorption capacity, fast desorption rate, and low relative heat load, exhibiting superior overall CO2 desorption and regeneration performance.

[0073] Comparative Example 10 Based on Experiment 2, PZ, DETA, and MDEA were adjusted to 5%AMP + 20%AEP + 15%MMEA.

[0074] Comparative Example 11 Based on Experiment 2, PZ, DETA, and MDEA were adjusted to 10%AMP + 20%AEP + 5%MDEA.

[0075] Comparative Example 12 Based on Experiment 2, PZ, DETA, and MDEA were adjusted to 10%AMP + 20%HMDA + 5%MMEA.

[0076] Comparative Example 13 Based on Experiment 2, PZ, DETA, and MDEA were adjusted to 10%AMP + 20%HMDA + 5%MDEA.

[0077] The CO2 desorption performance of the composite amine system in Comparative Example 2 and Comparative Examples 10-13 is shown in Table 5.

[0078] Table 5. Comparison of desorption performance of the complex amine systems in Example 2 and Comparative Examples 10-13. The relative heat loads in Table 5 are relative to the relative heat loads in Comparative Example 1.

[0079] As shown in Table 5, when comparative examples 10-13 were formulated with other composite amine formulations, the total CO2 desorption capacity and the 750s desorption capacity were significantly reduced, while the relative heat load increased. Although some comparative examples had higher maximum desorption rates, their cumulative desorption capacity was lower and their energy consumption was higher. Considering the total desorption capacity, 750s desorption capacity, maximum desorption rate, and relative heat load, the 5PZ+30DETA+5MDEA composite amine system used in Example 2 can achieve higher cumulative CO2 desorption capacity and lower desorption heat load while maintaining a higher desorption rate, exhibiting superior overall CO2 desorption performance. This indicates that the specific combination and ratio of PZ, DETA, and MDEA play an important role in improving the desorption and regeneration performance of the composite amine system.

[0080] In summary, when the ZrO2 / MCM-41 catalyst is used in the desorption process of CO2-rich amine solutions with a preferred composite amine absorbent, it can further enhance CO2 desorption based on the already good desorption performance of the composite amine absorbent. The CO2 composite capture system of this invention combines high total desorption capacity, 750s desorption capacity, maximum desorption rate, and low heat load, which helps to achieve efficient and low-energy-consumption desorption of carbon dioxide.

[0081] It should be noted that the above embodiments are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is impossible to exhaustively list all possible implementations here. All obvious variations or modifications derived from the technical solutions of this invention are still within the scope of protection of this invention.

Claims

1. A CO2 composite capture system, characterized in that, The catalyst includes a ZrO2 / MCM-41 catalyst, wherein the ZrO2 / MCM-41 catalyst comprises an MCM-41 molecular sieve support and ZrO2 supported on the MCM-41 molecular sieve support; And a complex amine absorbent, which, by weight, comprises 3-7 parts piperazine, 3-7 parts N-methyldiethanolamine and 20-40 parts a third amine component, wherein the third amine component is diethylenetriamine or hexamethylenediamine.

2. The CO2 composite capture system according to claim 1, characterized in that, The mass-to-volume ratio of ZrO2 / MCM-41 catalyst to composite amine absorbent is 1-20 g / L.

3. The CO2 composite capture system according to claim 1, characterized in that, The composite amine absorbent further includes a solvent by weight; preferably, the solvent is water; more preferably, the composite amine absorbent contains 3-7 parts piperazine, 3-7 parts N-methyldiethanolamine and 20-30 parts diethylenetriamine.

4. The CO2 composite capture system according to claim 1, characterized in that, The ZrO2 / MCM-41 catalyst is a powdered solid catalyst.

5. The CO2 composite capture system according to claim 1, characterized in that, The preparation method of the ZrO2 / MCM-41 catalyst includes the following steps: Disperse the MCM-41 molecular sieve and adjust the pH to 9-10 to obtain a suspension; The zirconium precursor solution was added dropwise to the suspension, and stirring was continued after the addition was complete. After the reaction was completed, the product was collected, washed, dried, and calcined to obtain the ZrO2 / MCM-41 catalyst.

6. The CO2 composite capture system according to claim 5, characterized in that, The zirconium precursor solution is one or more of ZrCl4, ZrOCl2, and Zr(NO3)4; the concentration of the zirconium precursor solution is 1-5 g / 100 mL.

7. The CO2 composite capture system according to claim 5, characterized in that, The reaction time is 2-8 hours; the concentration of the suspension is 5-15 g / 100 mL; the calcination temperature is 500-800℃, the time is 1-4 hours, and the heating rate is 1-4℃ / min.

8. The application of the CO2 composite capture system according to any one of claims 1-7 in the amine-based CO2 capture process.

9. The application according to claim 8, characterized in that, In the aforementioned application, the desorption temperature during the capture process is 60-120℃; the ZrO2 / MCM-41 catalyst is added to the composite amine absorbent, stirred evenly, and then used for desorption.

10. A method for capturing CO2, characterized in that, Includes the following steps: S1. The composite amine absorbent absorbs CO2 to a predetermined load to obtain a CO2-rich composite amine absorbent solution. S2. Add ZrO2 / MCM-41 catalyst to CO2-rich composite amine absorbent to obtain desorption solution; S3. Desorb the desorption solution by heating; The composite amine absorbent, by weight, comprises 3-7 parts piperazine, 3-7 parts N-methyldiethanolamine, and 20-40 parts a third amine component, wherein the third amine component is diethylenetriamine or hexamethylenediamine. The ZrO2 / MCM-41 catalyst comprises an MCM-41 molecular sieve support and ZrO2 supported on the MCM-41 molecular sieve support.

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