Layered porous TiO2 catalyst for regeneration of carbon dioxide absorbent as well as preparation method and application of layered porous TiO2 catalyst

Abstract

The invention belongs to the technical field of carbon dioxide capture, and particularly relates to a layered porous TiO2 catalyst for regeneration of a carbon dioxide absorbent and a preparation method and application of the layered porous TiO2 catalyst. The preparation method of the catalyst comprises the following steps: (1) dissolving P123 in an HCl ethanol solution, stirring and adding titanate, stirring for 0.5 h, slowly adding PMMA, and continuously stirring for 3 h to obtain a mixed solution; (2) putting the mixed solution into a high-pressure kettle, reacting for more than 2 hours at the temperature of 300 DEG C, and cooling to room temperature after the reaction is finished; and (3) washing the solution prepared in the step (2), centrifuging to obtain a precipitate, drying, and calcining to obtain the layered porous TiO2 catalyst. The layered porous TiO2 prepared by the invention is used as a catalyst, and in a reaction system with an MEA solution as an absorbent, a large amount of CO2 can be desorbed at low temperature, and the reaction rate during the desorption period can be effectively improved.

Description

Technical Field

[0001] This invention belongs to the field of carbon dioxide capture technology, specifically relating to a layered porous TiO2 catalyst for carbon dioxide absorbent regeneration, its preparation method, and its application. Background Technology

[0002] The extensive use of fossil fuels generates large amounts of carbon dioxide (CO2), leading to global warming and exacerbating the greenhouse effect. Currently, CO2 capture, transport, and storage (CCUS) technology has become an effective means of controlling industrial CO2 emissions, and it has profound significance for solving prominent environmental problems such as global warming and the greenhouse effect. Among various CO2 capture technologies, chemical absorption is currently the most mature method for capturing CO2 from industrial and power plant flue gas. Its core lies in using alkanolamine solutions (such as MEA, DEA, etc.) as absorbents. Among these, the technology using ethanolamine (MEA) solution is the most widely studied and has been widely applied in industry, often serving as a reference benchmark for various CO2 capture technologies. However, the bottleneck of this technology lies in the fact that its reverse reaction (i.e., the CO2 desorption process) requires a large amount of energy: the desorption reaction itself is a strongly endothermic process, requiring high-temperature (usually 100–120°C) steam heating of the rich liquid to release CO2, resulting in this step accounting for 70%–80% of the total energy consumption of the entire capture process. This high energy consumption significantly increases operating costs, becoming a major obstacle to the large-scale application of chemical absorption methods.

[0003] Currently, existing literature reports that using appropriate catalysts can lower the activation energy of CO2 desorption and increase the reaction rate, allowing the desorption reaction to proceed under mild conditions below 100℃. This significantly reduces energy consumption and amine solution loss to a certain extent. Previous literature has mentioned the application of solid catalysts in CO2 absorption and desorption, and results show that solid catalysts have demonstrated improvements in low-temperature CO2 desorption from amine solutions. Solid catalysts revolutionize traditional desorption technologies with three major advantages: reduced energy consumption, improved stability, and enhanced process flexibility. In terms of energy consumption, solid catalysts, through active site regulation, can reduce the desorption temperature from 120-140℃ to 80-100℃, reducing energy consumption by 20%-40%. Regarding stability, their heterogeneous characteristics avoid the degradation and equipment corrosion problems associated with traditional amine solutions, maintaining high activity even during recycling, thus reducing maintenance costs. In terms of process flexibility, solid catalysts can operate over a wide temperature range of 60-200℃, adapting to various exhaust gas conditions. Their porous structure supports multi-component reaction modes and can be coupled with renewable energy and other carbon capture technologies. However, due to problems such as insufficient catalytic activity, slow reaction kinetics at low temperatures, and weak resistance to poisoning, the practical application of some solid catalysts is still limited by performance bottlenecks and cost pressures. Therefore, in order to improve the application of solid catalysts in low-temperature CO2 desorption, it is urgent to develop novel solid catalysts with high stability, insolubility, significant reduction in activation energy, and high efficiency in improving low-temperature desorption efficiency. Summary of the Invention

[0004] In view of the problems and shortcomings of the existing technology, the purpose of this invention is to provide a layered porous TiO2 catalyst for carbon dioxide absorbent regeneration, its preparation method and application.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] The first aspect of this invention provides a method for preparing a layered porous TiO2 catalyst for carbon dioxide absorbent regeneration, comprising the following steps:

[0007] (1) Dissolve P123 in HCl ethanol solution, add titanate ester with stirring, stir for 0.5 hours, slowly add PMMA and continue stirring for 3 hours to obtain a mixed solution; the titanate ester is any one of tetrabutyl titanate, tetraethyl titanate, and tetraisopropyl titanate.

[0008] (2) Place the mixed solution in a high-pressure reactor and react at 300°C for more than 2 hours. After the reaction is completed, cool to room temperature.

[0009] (3) The solution obtained in step (2) is washed, centrifuged to obtain a precipitate, dried and calcined to obtain a layered porous TiO2 catalyst.

[0010] Preferably, in step (1), the mass ratio of P123, titanate and PMMA is 6:(2.5~20):15.

[0011] Preferably, in step (1), the HCl concentration in the HCl ethanol solution is 1 to 3 mol / L.

[0012] Preferably, in step (2), the reaction time is 3 to 24 hours.

[0013] Preferably, in step (3), the washing is performed three times each with deionized water and ethanol.

[0014] Preferably, in step (3), the drying temperature is 80-120°C and the drying time is 8-36 hours.

[0015] Preferably, in step (3), the calcination temperature is 550-800℃ and the calcination time is 4-6h.

[0016] A second aspect of the present invention provides a layered porous TiO2 catalyst prepared by the method described in the first aspect.

[0017] The third aspect of the present invention provides the application of the layered porous TiO2 catalyst described in the second aspect in the regeneration of carbon dioxide absorbent.

[0018] The fourth aspect of this invention provides a method for regenerating a carbon dioxide absorbent, wherein the layered porous TiO2 catalyst described in the second aspect is added to a carbon dioxide-rich amine solvent, and carbon dioxide is catalytically desorbed at 75-95°C to complete the regeneration of the carbon dioxide absorbent; the amount of the layered porous TiO2 catalyst is 20wt%-35wt% of the carbon dioxide-rich amine solvent.

[0019] Preferably, the amine solvent is any one of ethanolamine, methyldiethanolamine, diethanolamine, and triethanolamine.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] (1) The method of this invention uses titanate ester as the titanium source to synthesize a layered porous TiO2 catalyst in an acidic ethanol system. The acidic environment inhibits rapid hydrolysis and promotes the formation of a uniform sol; low-temperature crystallization directly generates a high-purity anatase phase, avoiding pore collapse caused by high-temperature calcination; the product has a high specific surface area, interconnected channels, and abundant surface hydroxyl groups, significantly improving the catalytic desorption and mass transfer efficiency of CO2. This invention simplifies the steps, reduces the risk of impurities, and is suitable for the green preparation of high-performance layered porous TiO2 catalysts. The layered porous TiO2 catalyst plays a synergistic role in CO2 desorption through its multi-level pore structure: mesopores provide abundant active sites and high specific surface area to enhance CO2 adsorption, macropores act as fast gas transport channels to promote CO2 diffusion, and micropores reduce the desorption activation energy through confinement effect; at the same time, the hydroxyl groups and anatase crystal phase on the material surface further optimize the CO2 adsorption-desorption balance, making the entire desorption process efficient and recyclable. This combination of multi-scale pore structure and surface properties significantly improves CO2 desorption kinetics and material stability.

[0022] (2) The layered porous TiO2 catalyst prepared in this invention can effectively reduce the desorption temperature to 75-95℃, thereby reducing the energy requirement of the reaction and reducing energy consumption during the desorption process. In addition, in the reaction system with amine solution as absorbent, the catalyst of this invention can not only desorb a large amount of CO2 at low temperature, but also effectively improve the reaction rate during desorption. The maximum CO2 desorption amount can reach 98.69 mmol CO2 / mol amine, and the maximum CO2 desorption rate can reach 3.06 mmol CO2 / min.

[0023] (3) The layered porous TiO2 of the present invention is more stable and insoluble in amine solution, which makes the catalyst easy to separate and regenerate. Attached Figure Description

[0024] Figure 1 The XRD characterization images are of the samples prepared in Examples 1 to 8 of this invention.

[0025] Figure 2 These are electron microscope images of the samples prepared in Examples 2 to 5 of the present invention. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0027] Example 1:

[0028] A method for preparing a layered porous TiO2 catalyst for carbon dioxide absorbent regeneration, the specific preparation steps are as follows:

[0029] (1) Add a small amount of ethanol to a 100ml beaker, add 4.17ml of concentrated hydrochloric acid to it using a pipette, then add more ethanol and bring the volume to 50ml. Dissolve 6g of P123 in 50ml of 1mol / L HCl ethanol solution and stir vigorously at room temperature to obtain a homogeneous solution. While stirring, add 20g of tetrabutyl titanate to the solution. After stirring for half an hour, slowly add 15g of polymethyl methacrylate (PMMA) to the solution and continue stirring for 3 hours to obtain a mixed solution.

[0030] (2) Transfer the mixed solution obtained in step (1) to a stainless steel-lined polytetrafluoroethylene autoclave with a capacity of 100 mL, keep the autoclave at 300 °C for 3 h, and cool the solution to room temperature after the reaction is completed.

[0031] (3) Wash the solution obtained in step (2) with deionized water and ethanol respectively, centrifuge, collect the precipitate after centrifugation, dry the precipitate in an oven at 120℃ for 24h, and finally heat the dried solid to 600℃ at a heating rate of 1℃ / min and calcine for 4h to obtain the layered porous TiO2 catalyst.

[0032] Example 2:

[0033] The content of Example 2 is basically the same as that of Example 1, except that the reaction time in step (2) is 4 hours.

[0034] Example 3:

[0035] The content of Example 3 is basically the same as that of Example 1, except that the reaction time in step (2) is 8 hours.

[0036] Example 4:

[0037] The content of Example 4 is basically the same as that of Example 1, except that the reaction time in step (2) is 12 hours.

[0038] Example 5:

[0039] The content of Example 5 is basically the same as that of Example 1, except that the reaction time in step (2) is 24 hours.

[0040] Catalyst performance testing experiment:

[0041] A constant flow rate of CO2 gas was introduced into 300 ml of a 5 mol / L ethanolamine (MEA) solution. The CO2 was absorbed to saturation at a constant temperature of 40°C and 300 r / min, resulting in a CO2-rich solution with an initial loading of 0.5 ± 0.03 mol CO2 / mol MEA. Subsequently, 3 g of the catalyst prepared in Examples 1 to 5 was added to the CO2-rich solution. The oil bath temperature was raised to different temperatures (75°C, 78°C, 80°C, 85°C, 90°C, 95°C) at 300 r / min and maintained at a constant temperature. The solution was purged with N2 at a flow rate of 65 mL / min. After condensation and drying, the desorbed CO2 was continuously measured online using a TCD thermal conductivity detector. A blank experiment without catalyst was also performed. The catalytic performance of the layered porous TiO2 catalyst was calculated using a gas-phase method. The calculation methods for CO2 desorption amount and desorption rate are shown in equations (1) and (2), respectively.

[0042]

[0043] In the formula, n is the amount of CO2 desorbed, in mmol; F N2 N2 flow rate, mL / min; t represents the volume fraction of CO2 in the gas mixture, %; t represents time, min; v represents the CO2 desorption rate, mmol CO2 / min.

[0044] The CO2 desorption amounts of Examples 1 to 5 and the blank experiment of this invention are shown in Table 1.

[0045] Table 1. Results of CO2 desorption measurement in Examples 1-5 and the blank experiment.

[0046]

[0047] As shown in Table 1, with the extension of reaction time (3h-24h), the CO2 desorption capacity of each embodiment showed a regular increase in the range of 75-95℃. Among them, Example 5 (24h) reached the highest desorption capacity (98.69mmol / mol) at 95℃, which was significantly improved by 18.5% compared with the blank experiment (83.27mmol / mol), indicating that extending the reaction time can effectively enhance the CO2 desorption performance of the catalyst. At the same time, the promoting effect of temperature increase on desorption capacity was consistent in all embodiments, especially in the range of 85-95℃, which confirmed the key influence of the synergistic optimization of temperature and reaction time on CO2 desorption efficiency.

[0048] The CO2 desorption rates of Examples 1 to 5 and the blank experiment of this invention are shown in Table 2.

[0049] Table 2 Results of CO2 desorption rate determination in Examples 1-5 and the blank experiment

[0050]

[0051] As shown in Table 2, the CO2 desorption rate of each example increased significantly with the extension of reaction time (3h-24h) and the increase of desorption temperature (75℃-95℃). Among them, Example 5 (24h) reached the highest rate (3.06mmol / min) at 95℃, which was 101% higher than the blank experiment (1.52mmol / min), confirming the synergistic enhancement effect of extending reaction time and increasing temperature on the desorption rate. At the same time, the rate increase was more significant after the temperature exceeded 85℃, indicating that the promoting effect of high temperature on the kinetic process is particularly critical.

[0052] Example 6:

[0053] The content of Example 6 is basically the same as that of Example 1, except that in step (1), the mass ratio of P123, tetrabutyl titanate and PMMA is 6:10:15.

[0054] Example 7:

[0055] The content of Example 7 is basically the same as that of Example 1, except that in step (1), the mass ratio of P123, tetrabutyl titanate and PMMA is 6:5:15.

[0056] Example 8:

[0057] The content of Example 8 is basically the same as that of Example 1, except that in step (1), the mass ratio of P123, tetrabutyl titanate and PMMA is 6:2.5:15.

[0058] Comparative example:

[0059] The content of the comparative example is basically the same as that of Example 1, except that PMMA is not added in step (1).

[0060] The CO2 desorption amount of Examples 6 to 8 and the comparative examples was determined according to the experimental methods described in the examples, and the results are shown in Table 3.

[0061] Table 3. Results of CO2 desorption measurement in Examples 6-8, comparative examples, and blank experiments.

[0062]

[0063] As shown in Table 3, increasing the amount of PMMA (from 2.5g to 15g) significantly improved the CO2 desorption capacity. In Example 1 (15g PMMA), the highest desorption capacity (96.77mmol / mol) was achieved at 95℃, which was 5.0% higher than that of the control group (without PMMA) and the blank experiment, and 16.2% higher than that of the blank experiment, respectively, confirming that the introduction of PMMA effectively enhanced the catalytic performance. At the same time, the desorption capacity of each example increased significantly after the temperature exceeded 85℃, showing that high temperature significantly promoted the reaction equilibrium.

[0064] The CO2 desorption rates of Examples 6 to 8 and the comparative examples were determined according to the experimental methods described in the examples, and the results are shown in Table 4.

[0065] Table 4. Results of CO2 desorption rate determination in Examples 6-8, comparative examples, and blank experiments.

[0066]

[0067] As shown in Table 4, the increase in PMMA dosage (from 2.5g to 15g) was positively correlated with the CO2 desorption rate. Among them, Example 1 (15g PMMA) reached the highest desorption rate (2.55mmol / min) at 95℃, which was 14.3% and 67.8% higher than the control ratio (without PMMA) and the blank experiment, respectively, proving that the introduction of PMMA significantly improved the kinetic performance of the catalyst. At the same time, the rate increase of each example was more obvious after the temperature exceeded 85℃, indicating that high temperature has a decisive role in improving the reaction rate.

[0068] Catalyst XRD characterization:

[0069] The layered porous TiO2 catalysts prepared in Examples 1 to 8 were characterized by XRD, and the results are as follows: Figure 1 As shown, from Figure 1 It can be seen that the peaks at 2θ = 25.4, 37.6, 48.0, 53.9 and 55.1° are attributed to the (101), (004), (200), (105) and (211) planes of anatase TiO2, which are consistent with the peak positions of the TiO2 standard card, confirming the presence of the anatase phase in the layered porous TiO2 catalyst prepared in this invention.

[0070] Catalyst morphology characterization:

[0071] Figure 2 Scanning electron microscope (SEM) images of the samples prepared in Examples 2 to 5, by Figure 2As can be seen, the layered porous TiO2 catalyst has a uniform pore size distribution, with a pore size of approximately 1 μm, indicating that the material has a highly ordered porous structure. This structure is beneficial for increasing the specific surface area and active sites, and can significantly improve the catalytic desorption and mass transfer efficiency of CO2.

[0072] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit the scope of protection of the present invention. Those skilled in the art can modify or make equivalent substitutions to the technical solutions of the present invention based on the concept of the present invention, without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for the preparation of a layered porous TiO2catalyst for the regeneration of carbon dioxide absorbents, characterized by, The method comprises the following steps: (1) dissolving P123 in a HCl ethanol solution, stirring to add a titanium ester, stirring for 0.5 hours, then slowly adding PMMA and continuing to stir for 3 hours to obtain a mixed solution; the titanium ester is any one of tetrabutyl titanate, tetraethyl titanate, and tetraisopropyl titanate; (2) placing the mixed solution in an autoclave and reacting at 300℃ for more than 2 hours, and then cooling to room temperature; (3) washing and centrifuging the solution obtained in step (2) to obtain a precipitate, drying and calcining the precipitate to obtain a layered porous TiO2 catalyst.

2. The method for preparing a layered porous TiO2 catalyst for regeneration of a carbon dioxide absorbent according to claim 1, characterized by, In step (1), the mass ratio of P123, the titanium ester, and PMMA is 6:(2.5-20):

15.

3. The method for preparing a layered porous TiO2 catalyst for regeneration of a carbon dioxide absorbent according to claim 1, characterized by, In step (1), the HCl concentration in the HCl ethanol solution is 1-3 mol / L.

4. The method for preparing a layered porous TiO2 catalyst for regeneration of a carbon dioxide absorbent according to claim 1, characterized by, In step (2), the reaction time is 3-24 hours.

5. The method for preparing a layered porous TiO2 catalyst for regeneration of a carbon dioxide absorbent according to claim 1, characterized by, In step (3), the washing is performed with deionized water and ethanol, each for 3 times.

6. The method for preparing a layered porous TiO2 catalyst for regeneration of a carbon dioxide absorbent according to claim 1, characterized by, In step (3), the drying temperature is 80-120℃, and the drying time is 8-36 hours; the calcining temperature is 550-800℃, and the calcining time is 4-6 hours.

7. A layered porous TiO2 catalyst prepared by the method of any one of claims 1-6.

8. The use of the layered porous TiO2 catalyst of claim 7 in the regeneration of a carbon dioxide absorbent.

9. A method for regenerating a carbon dioxide absorbent, characterized by, The layered porous TiO2 catalyst of claim 7 is added to an amine solvent rich in carbon dioxide, and the carbon dioxide is catalytically desorbed at 75-95℃ to complete the regeneration of the carbon dioxide absorbent; the amount of the layered porous TiO2 catalyst is 20wt%-35wt% of the amine solvent rich in carbon dioxide.

10. The method of claim 9, wherein the carbon dioxide absorbent is regenerated by, The amine solvent is any one of ethanolamine, methyldiethanolamine, diethanolamine, and triethanolamine. The amine solvent is any one of ethanolamine, methyldiethanolamine, diethanolamine, and triethanolamine.

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