Preparation method of CaO-based bifunctional material, CaO-based bifunctional material and application thereof
By preparing CaO-based bifunctional materials and adding acidic metal oxides as additives, the problem of insufficient CO2 adsorption and desorption capacity of CaO adsorbents at low temperatures was solved, achieving efficient CO2 capture and conversion to meet the needs of industrial applications.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CHONGQING UNIV
- Filing Date
- 2023-11-17
- Publication Date
- 2026-07-24
AI Technical Summary
Existing CaO adsorbents have insufficient CO2 adsorption and desorption capacity at low temperatures, resulting in a mismatch between CO2 capture and in-situ conversion times, which increases equipment cost and complexity.
CaO-based bifunctional materials are prepared by blending or reacting carbon-capturing metal precursors, catalyst metal precursors, auxiliary metal precursors, xylose, glycine, and urea to form a mixture, which is then calcined at 400-900℃. Acidic metal oxides are added as auxiliary agents to improve the reactivity.
It improves CO2 adsorption capacity and conversion rate, with a CO2 adsorption capacity greater than 48 wt.%, a maximum methane generation rate of 1.3 mmol/min, a CO2 conversion rate of over 99%, and stable cycle performance, meeting the needs of industrial applications.
Smart Images
Figure CN117504577B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of CO2 capture / conversion technology, specifically to a method for preparing CaO-based bifunctional materials and the CaO-based bifunctional materials themselves. Background Technology
[0002] Carbon capture, utilization, and storage (CCUS) technology is one of the necessary technical means to curb global warming in the medium and long term. However, its high cost and energy consumption have hindered its practical industrial application. To reduce the cost and energy consumption caused by the resistance to large-scale application, integrated carbon capture and utilization (ICCU) technology has been proposed based on CCUS. It uses bifunctional materials (DFM) to capture emitted CO2 in the same reactor and directly convert it into value-added chemical products or fuels, thereby reducing the cost and energy consumption of CCUS in the purification, compression, storage, and intermediate transportation processes.
[0003] Currently, ICCUs primarily convert captured CO2 directly into corresponding carbon compounds via the following CO2 conversion pathways, as shown in equations (1-5). As can be seen from equations (1-5), methanation in equation (1) is the only exothermic reaction. Compared to other CO2 conversion reactions, methanation can provide the heat required for adsorbent desorption of CO2, reducing energy supply. For current CO2 adsorbents, the greatest energy consumption comes from the energy required for CO2 desorption, while other CO2 conversion pathways undoubtedly exacerbate the energy required for CO2 desorption and in-situ conversion stages, especially with the CaO adsorbent widely used in ICCUs (equation 6).
[0004] CO2 + 4H2 → CH4 + 2H2O, ΔH (r，298K) = -164kJ·mol -1 (1)
[0005] CO2 + H2 → CO + H2O, ΔH (r，298K) = +41.2kJ·mol -1 (2)
[0006] CO2 + CH4 → 2CO + 2H2, ΔH (r，298K) = +247kJ·mol -1 (3)
[0007] 2CO2 + C2H6 → 4CO + 3H2, ΔH (r，298K) = +428.1 kJ·mol -1 (4)
[0008] CO2 + C2H6 → C2H4 + CO + H2O, ΔH (r298K) = +149kJ·mol -1 (5)
[0009] CaCO3→CO2+CaO,H2O→CO2+CaO,H2O 298K = +178kJ·mol -1 (6)
[0010] Meanwhile, ICCU-methanation offers another hydrogen storage method, a very attractive "electro-to-gas" technology. Therefore, in terms of cost and energy consumption, ICCU-methanation undoubtedly has the greatest potential for widespread application as hydrogen technology develops.
[0011] Ideally, when the in-situ conversion time is close to the CO2 capture time, two reaction devices can be used alternately to achieve continuous CO2 capture and in-situ conversion of industrial waste gas. CaO adsorbent is low in cost and has a large CO2 capacity, but its operation is limited by low operating temperature. When the temperature of CaO and ICCU methanation reaction is matched, the CO2 desorption reaction kinetics are slow. The in-situ conversion time is much longer than the CO2 capture time, which means that multiple reaction devices need to be added in practical applications to balance the CO2 capture time and the in-situ conversion time. This not only increases construction costs but also increases equipment space volume and operational complexity.
[0012] Therefore, it is necessary to improve CaO-based adsorbents to enhance their ability to absorb and desorb CO2 at low temperatures in order to achieve efficient and convenient ICCU-methanation. Summary of the Invention
[0013] To address the aforementioned shortcomings of existing technologies, the present invention aims to provide a method for preparing CaO-based bifunctional materials, the CaO-based bifunctional materials and their applications, which have the advantages of high CO2 adsorption capacity and fast conversion rate, and can basically maintain the capture time, thereby achieving efficient and convenient ICCU-methanation.
[0014] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:
[0015] A method for preparing a CaO-based bifunctional material, comprising,
[0016] A mixture is obtained by blending or reacting carbon capture metal precursor, catalyst metal precursor, auxiliary metal precursor, xylose, glycine and urea.
[0017] The mixture was calcined in air at 400-900℃ for 2-6 hours to obtain the CaO-based bifunctional material.
[0018] The molar ratio of the carbon capture metal precursor, catalyst metal precursor, auxiliary metal precursor, xylose, glycine and urea is (80-95):(1-10):(2.5-10):(80-240):(10-70):(30-210).
[0019] Preferably, the carbon-capturing metal precursor comprises a nitrate or a soluble organic acid salt containing Ca.
[0020] In specific implementation, the catalyst metal precursor is a nitrate or a soluble organic acid salt containing a catalytic metal element.
[0021] Preferably, the catalytic metal element includes Ni or Ru.
[0022] In practice, the auxiliary metal precursor includes nitrates or soluble organic acid salts containing auxiliary metal elements.
[0023] Preferably, the auxiliary metal element includes Ti, Zr, Cr, Zn, V, or W.
[0024] In practice, the mixture is prepared by impregnation, hydrothermal synthesis, or sol-gel methods.
[0025] Preferably, the mixture is prepared by hydrothermal synthesis, which involves mixing a carbon trapping metal precursor, a catalyst metal precursor, an auxiliary metal precursor, xylose, glycine, and urea evenly and completely dissolving them in deionized water, storing them at 100-200℃ for 24-72 hours, and then washing and drying them to obtain the mixture.
[0026] The present invention also discloses a CaO-based bifunctional material, characterized in that the CaO-based bifunctional material is prepared by the same method used for preparing CaO-based bifunctional materials.
[0027] The present invention also discloses an application of a CaO-based bifunctional material, which is used for CO2 capture and conversion.
[0028] Compared with the prior art, the present invention has the following advantages:
[0029] 1. The method for preparing CaO-based bifunctional materials provided by this invention involves blending or reacting a carbon trapping metal precursor, a catalyst metal precursor, an auxiliary metal precursor, xylose, glycine, and urea to form a mixture using impregnation, hydrothermal synthesis, or sol-gel methods. The mixture is then calcined to obtain the CaO-based bifunctional material. This method is simple and easy to operate.
[0030] 2. The CaO-based bifunctional material provided by this invention, due to the addition of acidic metal oxides as auxiliaries, enhances the adsorption and activity of *H, thereby facilitating its reaction with carbonates and accelerating the reaction rate. This CaO-based bifunctional material exhibits a CO2 adsorption capacity greater than 48 wt.%, demonstrating high CO2 adsorption capacity. Its highest methane formation rate is 1.3 mmol / min, which is six times the conversion rate of traditional Ni / CaO, essentially maintaining the same capture time. After five integrated CO2 capture / methanation processes, its adsorption performance does not decline, with a CO2 conversion rate exceeding 99% and a methane selectivity exceeding 99%. It possesses advantages such as rapid and stable cyclic adsorption-desorption / in-situ conversion performance, high conversion rate, and good product selectivity. Furthermore, this CaO-based bifunctional material maintains a high CO2 adsorption capacity even at low CO2 concentrations, meeting the needs of industrial applications. Attached Figure Description
[0031] Figure 1 This is a flowchart illustrating the preparation of CaO-based bifunctional materials using a hydrothermal method in an embodiment of the present invention.
[0032] Figure 2 This is a scan image of the bifunctional material prepared in Example 1 of the present invention.
[0033] Figure 3 This is a scan image of the bifunctional material prepared in Comparative Example 1.
[0034] Figure 4 This is a scan image of the bifunctional material prepared in Comparative Example 2.
[0035] Figure 5 This is a scan image of the bifunctional material prepared in Comparative Example 3.
[0036] Figure 6 The graphs show the CO2 capture / methanation integrated performance test results of the bifunctional materials prepared in Example 1 and Comparative Examples 1-3 of this invention.
[0037] Figure 7 This is a carbon capture cycle diagram of the bifunctional material prepared in Example 1 of the present invention when CO2 capture / methanation is integrated at 550°C.
[0038] Figure 8 The reaction curve of ICCU-methanation of the bifunctional material 2 prepared in Example 2 at 600 °C.
[0039] Figure 9 The adsorption diagrams of bifunctional material 1 prepared in Example 1, bifunctional material 2 prepared in Example 2, and NH3 prepared in Comparative Example 1 are shown.
[0040] Figure 10Comparison of ICCU-methanation performance of bifunctional material 1 prepared in Example 1 and bifunctional materials 3-5 prepared in Examples 3-5 at 600℃. Detailed Implementation
[0041] This invention discloses a method for preparing CaO-based bifunctional materials, comprising:
[0042] A mixture is obtained by blending or reacting carbon capture metal precursor, catalyst metal precursor, auxiliary metal precursor, xylose, glycine and urea.
[0043] The mixture was calcined in air at 400-900℃ for 2-6 hours to obtain the CaO-based bifunctional material.
[0044] The molar ratio of the carbon capture metal precursor, catalyst metal precursor, auxiliary metal precursor, xylose, glycine and urea is (80-95):(1-10):(2.5-10):(80-240):(10-70):(30-210).
[0045] This invention also discloses a CaO-based bifunctional material, characterized in that the CaO-based bifunctional material is prepared using the same preparation method as the CaO-based bifunctional material.
[0046] This invention also discloses an application of a CaO-based bifunctional material, which is used for CO2 capture and conversion.
[0047] I. Preparation of bifunctional materials
[0048] Example 1
[0049] This embodiment uses a hydrothermal synthesis method to prepare the mixture, and the preparation process is as follows: Figure 1 As shown. The following powder materials were weighed: carbon capture metal precursor Ca(NO3)2·4H2O, catalyst metal precursor Ni(NO3)2·6H2O, auxiliary metal precursor Zr(NO3)4·5H2O, xylose, glycine, and urea, with concentrations of 54.4 mmol, 6.8 mmol, 6.8 mmol, 160 mmol, 26.4 mmol, and 72 mmol, respectively. 100 mL of deionized water was added until the mixture was completely dissolved. The solution was transferred to a stainless steel autoclave lined with polytetrafluoroethylene and subjected to hydrothermal reaction at 180°C for 24 hours. After cooling to room temperature, the hydrothermal sample was repeatedly washed and filtered with anhydrous ethanol and deionized water, and then dried in an 80°C oven to obtain a mixture. The mixture was then calcined at 700°C for 6 hours to obtain a CaO-based bifunctional material, designated as bifunctional material 1. The scanning electron microscope image of the bifunctional material prepared in this example is shown below. Figure 2 .from Figure 2As can be seen from the image, the CaO-based bifunctional material has a prismatic structure. Further elemental scanning diagrams confirm that Zr and Ni elements were successfully loaded onto CaO.
[0050] Comparative Example 1
[0051] The bifunctional material prepared in this comparative example differs from that in Example 1 in that, during the preparation process, the carbon-capturing metal precursor Ca(NO3)2·4H2O was 61.2 mmol, and no auxiliary metal precursor Zr(NO3)4·5H2O was added. The rest is the same as in Example 1, and it is referred to as Comparative Example 1.
[0052] The scanning image of the bifunctional material prepared in Comparative Example 1 is shown below. Figure 3 ,from Figure 3 As can be seen from the image, the material exhibits a spherical structure, and further elemental scanning diagrams confirm that Ni was successfully loaded onto CaO.
[0053] Comparative Example 2
[0054] The bifunctional material prepared in this comparative example differs from that in Example 1 in that the auxiliary metal precursor Zr(NO3)4·5H2O was replaced with Ce(NO3)3·4H2O during the preparation process, while the molar number remained unchanged. The rest was the same as in Example 1, and this is referred to as Comparative Example 2.
[0055] The scanning image of the bifunctional material prepared in Comparative Example 2 is shown below. Figure 4 ,from Figure 4 As can be seen from the data, the material exhibits a multi-spherical polymer structure, and further elemental scanning plots confirm that Ce and Ni elements were successfully loaded onto CaO.
[0056] Comparative Example 3
[0057] The bifunctional material prepared in this comparative example differs from that in Example 1 in that the auxiliary metal precursor Zr(NO3)4·5H2O was replaced with Mg(NO3)2·6H2O during the preparation process, while the molar number remained unchanged. The rest was the same as in Example 1, and it is referred to as Comparative Example 3.
[0058] The scanning image of the bifunctional material prepared in Comparative Example 3 is shown below. Figure 5 ,from Figure 5 As can be seen from the data, the functional material -3 has a prismatic structure, and further elemental scanning diagrams prove that Mg and Ni elements were successfully loaded onto CaO.
[0059] Example 2
[0060] A CaO-based bifunctional material is prepared using an impregnation method, the specific preparation method of which includes:
[0061] Weigh 54.4 mmol of nano-calcium carbonate and 6.8 mmol of Zr(NO3)4·5H2O into a 100 mL beaker. Add 10 mL of deionized water to dissolve the Zr(NO3)4·5H2O. Stir in an 80 °C water bath until the water in the beaker is completely evaporated, allowing the dissolved Zr(NO3)4·5H2O to precipitate on the nano-calcium carbonate. Then, transfer the mixture to a crucible and place the crucible in a muffle furnace. Heat the crucible to 550 °C in air and hold for 5 hours. After cooling to room temperature, obtain the calcined powder sample. The calcined powder sample and 6.8 mmol of Ni(NO3)2·6H2O were placed in a 100 mL beaker, and 10 mL of deionized water was added to dissolve Zr(NO3)4·5H2O. The mixture was stirred in an 80 °C water bath until the water in the beaker was completely evaporated, allowing the dissolved Ni(NO3)2·6H2O to precipitate on the calcined powder sample. Finally, the mixture was placed in a crucible and heated in a muffle furnace to 550 °C and held for 5 hours. After cooling to room temperature, the sample was removed to obtain a CaO-based bifunctional material, denoted as bifunctional material 2.
[0062] Examples 3-5
[0063] The preparation methods of the bifunctional materials in Examples 3-5 are the same as those in Example 1. Their components and formulations are shown in Table 1 and are respectively referred to as bifunctional material 3, bifunctional material 4 and bifunctional material 5.
[0064] Table 1. Composition and proportions of the bifunctional materials prepared in Examples 3-5, mol.%
[0065] Example 3 85 mol% CaO <![CDATA[5mol.%ZrO2]]> 10 mol.% Ni Example 4 87.5 mol.% CaO <![CDATA[2.5mol.%ZrO2]]> 10 mol.% Ni Example 5 89 mol.% CaO <![CDATA[1mol.%ZrO2]]> 10 mol.% Ni
[0066] II. Performance Testing
[0067] The bifunctional material 1 prepared in Example 1 and the materials prepared in Comparative Examples 1-3 were subjected to integrated CO2 capture / methanation performance tests. The operating temperature was 550℃. For the first 30 minutes, a mixed gas of CO2 / N2 with a concentration of 15 vol.% was introduced to simulate flue gas for carbon capture. After carbon capture, the introduced gas was changed to pure H2 to carry out in-situ methanation reaction. The test results are as follows. Figure 6 As shown.
[0068] from Figure 6As shown in Figure (a), the methanation time for material 1 (i.e., pure Ni) exceeds 150 min, with a maximum conversion rate of 0.26 mmol / min. When other metals are added, such as material 2 (i.e., CeO2 / CaO bifunctional material) in Figure (c) and material 3 (i.e., MgO / CaO bifunctional material) in Figure (d), the in-situ conversion rate can be effectively improved to some extent by reducing the specific gravity of CaO and increasing its dispersibility. However, the methanation time still exceeds 80 min, and the maximum conversion rate is around 0.44 mmol / min. In contrast, the methanation of bifunctional material 1, which incorporates acidic metal oxide (ZrO2) as an auxiliary agent, is completed within 40 min, as shown in Figure (b). The maximum conversion rate is 1.3 mmol / min, which is 5 times that of the traditional Ni / CaO conversion rate. This essentially matches the capture time, achieving better integration of capture and conversion.
[0069] The carbon capture capacity of the bifunctional material 1 prepared in Example 1 during CO2 capture / methanation integration at 550°C is as follows: Figure 7 As shown. From Figure 7 As can be seen, in real simulated flue gas containing water vapor and oxygen, CaO-based bifunctional materials maintain good carbon capture and recycling performance, which can meet the requirements of actual industrial applications.
[0070] The reaction curve of the bifunctional material 2 prepared in Example 2 at 600℃ using ICCU-methanation is shown below. Figure 8 As shown. The NH3 adsorption of bifunctional material 1, bifunctional material 2, and comparative example 1 is as follows. Figure 9 As shown. From Figure 8 and 9 It is evident that the addition of an acidic metal is key to altering the in-situ methanation rate. Different preparation methods for the same acidic metal oxide result in varying acid strengths and methanation rates. The stronger the acid, the faster the methanation rate.
[0071] The ICCU-methanation properties of the bifunctional material 1 prepared in Example 1 and the bifunctional materials prepared in Examples 3-5 at 600°C are compared. Figure 10 As shown. From Figure 10 As can be seen, with the increase of ZrO2 content, its methanation rate increases significantly until the ZrO2 content reaches 5 mol.%, at which point the methanation rate begins to remain constant.
[0072] As can be seen, the CaO-based bifunctional material provided in this embodiment of the invention has a CO2 adsorption capacity greater than 48 wt.%, exhibiting the advantage of high CO2 adsorption capacity. Its highest conversion rate is 1.3 mmol / min, which is 5 times that of traditional Ni / CaO, essentially maintaining the same capture time. After five integrated CO2 capture / methanation processes, the adsorption performance does not decrease, with a CO2 conversion rate exceeding 99% and a methane selectivity exceeding 99%. It possesses advantages such as rapid and stable cyclic adsorption-desorption / in-situ conversion performance, high conversion rate, and good product selectivity. Furthermore, this CaO-based bifunctional material still exhibits a high CO2 adsorption capacity at low CO2 concentrations, meeting the needs of industrial applications.
[0073] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.
Claims
1. The application of a CaO-based bifunctional material in carbon capture and methanation conversion, characterized in that, include, The mixture was prepared by hydrothermal synthesis. The mixture prepared by hydrothermal synthesis includes mixing carbon trapping metal precursor, catalyst metal precursor, auxiliary metal precursor, xylose, glycine and urea evenly and completely dissolving them in deionized water, storing at 100-200℃ for 24-72h, washing and drying to obtain the mixture. The mixture was calcined in air at 400-900℃ for 2-6 hours to obtain the CaO-based bifunctional material. The molar ratio of the carbon capture metal precursor, catalyst metal precursor, auxiliary metal precursor, xylose, glycine and urea is (80-95):(1-10):(2.5-10):(80-240):(10-70):(30-210). Additive metal precursors include nitrates or soluble organic acid salts containing additive metal elements; The auxiliary metal element is Zr.
2. The application according to claim 1, characterized in that, The carbon-capturing metal precursor includes nitrates or soluble organic acid salts containing Ca.
3. The application according to claim 1, characterized in that, The catalyst metal precursor is a nitrate or a soluble organic acid salt containing a catalytic metal element.
4. The application according to claim 3, characterized in that, The catalytic metal element includes Ni or Ru.