A calcium-aluminum-based carbon dioxide capture material and preparation method

Abstract

The present invention belongs to the technical field of preparation of environmental energy materials, and specifically relates to a calcium-aluminum-based carbon dioxide capture material and a preparation method. The calcium-aluminum composite material includes CaO and γ-, δ- and α-Al2O3. CaO is used as an active material for carbon dioxide capture, and Al2O3 is used as a structural support material for CaO, which further improves the stability of the CaO material during repeated carbon dioxide capture. The problem of the prior art calcium-aluminum materials being extremely prone to failure, poor cycle performance, and high requirements for raw materials in the carbon dioxide capture process is solved. The preparation method of the present invention is simple and controllable, has low equipment requirements, low energy consumption, simple steps, and excellent performance of the obtained product, and is easy to industrialize and apply.

Description

Technical Field

[0001] The present invention belongs to the technical field of preparation of environmental energy materials, and specifically relates to a calcium-aluminum-based carbon dioxide capture material and a preparation method thereof. Background Art

[0002] To achieve the "dual carbon" goals and promote green, low-carbon development, research on various materials in the energy system is crucial. Although significant progress has been made in various energy system research areas, the use of fossil fuels will not be completely replaced in the foreseeable future. The combustion of fossil fuels undoubtedly emits large amounts of CO2 into the atmosphere. As a result, atmospheric CO2 concentrations have continued to increase over the past few decades, leading to global climate change, the most challenging issue of the 21st century. The problem of excessive atmospheric CO2 concentrations requires effective measures to address it. CO2 capture and utilization (CCU) technology is considered one of the most promising technologies for achieving temperature goals. The CO2 capture process accounts for 70% of the total CCU cost, making front-end carbon capture crucial for achieving breakthroughs in CCU technology. Carbon capture provides a truly green source of carbon for subsequent utilization. CCU technology can be used to reduce CO2 emissions in industries with significant CO2 emissions, such as steel and coal combustion.

[0003] Common CO2 capture materials include alkali metal oxide composites (such as CaO and MgO), amines, zeolites, and MOFs. Alkali metal oxide composites are common CO2 adsorption materials. Calcium-based materials, among others, have the advantages of high theoretical adsorption capacity (0.78 g CO2 / g), wide raw material availability (such as limestone and various shells), and low cost. In recent years, they have become the subject of research as solid CO2 adsorbents. Ideal CO2 capture materials should possess suitable adsorption heat, stable cyclic performance, good thermochemical stability, fast kinetics, and strong sensitivity. The adsorption process of CaO can be divided into two steps: chemical reaction and internal diffusion. First, CO2 reacts chemically with the CaO surface, then gradually diffuses into the CaO interior through its pores. As the reaction progresses, newly formed calcium carbonate increases on the sample surface, eventually blocking the CaO surface pores and preventing further CO2 diffusion. At present, the research strategies for CaO-based materials mainly include reducing the size of CaO itself, designing the material structure (shell-core, porous, defective structure), CaO composite materials (CaO-SiO2, CaO-Al2O3), etc., to further improve the CO2 adsorption cyclic stability of the composite materials.

[0004] Due to its higher melting point and stable structure, Al2O3 is considered to be one of the best supports for CaO as a carbon capture material and a better performing adsorbent. However, Al2O3 has multiple phases (γ-, δ- and α-Al2O3), each with its own unique structure and formation energy. γ-Al2O3 is the most important phase, but other high-temperature Al2O3 derived from γ-Al2O3 also play a vital role in many fields. Compared with γ-Al2O3, they have smaller surface area, less structural disorder and higher thermodynamic stability, which will affect the effectiveness of Al2O3 as a stable support for CaO in the CO2 capture process.

[0005] The innovation of this invention is that it is the first to explore the CO2 capture performance, especially the carbon dioxide cyclic capture performance, of various phases of Al2O3 when combined with CaO; this fills the gap in this research in the field of carbon dioxide capture. Summary of the Invention

[0006] In order to solve the problem of material deactivation of calcium-aluminum-based composite materials in the CO2 capture cycle in the existing technology, the present invention attempts for the first time to combine x-Al2O3 with CaO and prepare a calcium-aluminum-based CO2 capture composite material with excellent CO2 capture cycle performance through sintering.

[0007] The present invention provides a calcium-aluminum-based composite material, comprising aluminum oxide (x-Al2O3) and CaO of different phases; the composite material is obtained by mixing a CaO precursor and x-Al2O3 and then calcining; the mass ratio of the obtained CaO to x-Al2O3 is 7-9:3-1; the calcination temperature is greater than the decomposition temperature of the precursor and less than the temperature at which gamma aluminum oxide (γ-Al2O3) is converted into alpha aluminum oxide (α-Al2O3).

[0008] Preferably, the composite material includes γ-Al2O3 and CaO; the composite material is obtained by mixing a CaO precursor and x-Al2O3 and then calcining; the mass ratio of the prepared calcium oxide to Al2O3 is 7-9:3-1; the calcination temperature is greater than the decomposition temperature of the precursor and less than the temperature at which γ-Al2O3 is converted into alpha alumina.

[0009] The present invention provides a calcium-aluminum-based composite material, wherein the precursor used is at least one selected from calcium acetate, calcium carbonate and calcium nitrate.

[0010] The calcium-aluminum-based composite material of the present invention is preferably calcined at a temperature of 700-950°C, more preferably 820-900°C.

[0011] The invention discloses a calcium-aluminum-based composite material, and the calcination time is 1-3 hours.

[0012] In the present invention, the calcination temperature cannot be too high and the calcination time cannot be too long, otherwise the composite material will be over-sintered and deactivated; the calcination temperature cannot be too low and the calcination time cannot be too short, otherwise the CaO precursor will not be decomposed or will be completely decomposed.

[0013] The present invention provides a method for preparing a calcium-aluminum-based composite material, comprising the following steps:

[0014] The raw materials are taken according to the designed composition ratio, and then mixed evenly. After mixing evenly, they are calcined at 700-950° C., preferably 850-900° C. to obtain the product. The raw materials include a CaO precursor and x-Al2O3.

[0015] In the present invention, x-Al2O3 is selected from γ-Al2O 3、 At least one of δ-Al2O3 and α-Al2O3. The composite material is prepared using x-Al2O3, which reacts with calcium oxide to generate different calcium aluminates after sintering.

[0016] The invention discloses a preparation method of a calcium-aluminum-based composite material. The method comprises the following steps: uniformly mixing the materials through ball milling; controlling the rotation speed to be 600-800 r / min during ball milling; carrying out the ball milling for 4-8 hours; and achieving a ball-to-material mass ratio of 8:1.

[0017] The invention discloses a preparation method of a calcium-aluminum-based composite material, wherein the calcination time is 1-3 hours.

[0018] The present invention provides a method for preparing a calcium-aluminum-based composite material, wherein the γ-Al2O3 used is commercial γ-Al2O3 with a particle size of less than or equal to 1 μm.

[0019] The present invention provides a method for preparing a calcium-aluminum-based composite material. In the composite material, the mass ratio of CaO to Al2O3 is 7-9:3-1, preferably 7.5-8.5:1.5-2.5.

[0020] As a preferred embodiment, the present invention sintered γ-Al2O3 at 900°C to obtain δ-Al2O; then, δ-Al2O and calcium acetate precursor were ball-milled and mixed, and sintered at high temperature to obtain CaO@γ-Al2O3 composite material; wherein,

[0021] The ball milling conditions were 800 r / min, the ball milling time was 6 h, and the ball-to-material mass ratio was 8:1;

[0022] The high-temperature sintering temperature was 900°C, and the sintering schedule was 0-500°C at 5°C / min, 500-800°C at 10°C / min, and 800-900°C at 5°C / min, with a 2-hour hold. After high-temperature sintering, the mass ratio of calcium oxide to aluminum oxide was 8:2. This method demonstrated significantly higher cyclic performance and higher total carbon dioxide absorption over 20 cycles than other methods, achieving unexpected results.

[0023] The calcium-aluminum-based composite material designed and prepared by the present invention has an initial carbon dioxide capture capacity of 0.52g CO2 / g adsorbent after optimization. After 20 cycles, the carbon dioxide capture capacity is 0.46g CO2 / g adsorbent, and the cycle retention rate is 88.5%.

[0024] Beneficial effects of the embodiments of the present invention

[0025] 1. The calcium-aluminum-based composite material designed and prepared by the present invention explored the influence of x-Al2O3 on the calcium-aluminum-based composite material for the first time. After optimization, a composite material with the best performance was obtained. Its initial carbon dioxide capture capacity was 0.52g CO2 / g adsorbent. After 20 cycles, the carbon dioxide capture capacity could still be 0.46g CO2 / g adsorbent, and the cycle retention rate was 88.5%.

[0026] 2. The present invention has low requirements on equipment, low energy consumption, simple steps, high controllability, and is easy for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is the XRD pattern of x-Al2O3 prepared in Example 1.

[0028] Figure 2 This is the XRD pattern of the pure CaO material prepared in Example 2.

[0029] Figure 3 3 is an XRD pattern of the CaO / γ-Al2O3 composite material prepared when the mass ratio of calcium oxide prepared from calcium acetate to aluminum oxide is 8:2 in Example 3.

[0030] Figure 4 3 is an XRD pattern of the CaO / δ-Al2O3 composite material prepared when the mass ratio of calcium oxide prepared from calcium acetate to aluminum oxide is 8:2 in Example 3.

[0031] Figure 5 3 is an XRD pattern of the CaO / α-Al2O3 composite material prepared when the mass ratio of calcium oxide prepared from calcium acetate to aluminum oxide is 8:2 in Example 3.

[0032] Figure 6This is a graph of the carbon dioxide capture performance of the pure CaO material prepared in Example 4, Performance Test Example 1 (20 times).

[0033] Figure 7 This is a graph of the carbon dioxide capture performance (20 times) of the CaO / α-Al2O3 composite material (the mass ratio of the obtained calcium oxide to aluminum oxide is 8:2) in Performance Test Example 2, Example 4.

[0034] Figure 8 This is a graph of the carbon dioxide capture performance (20 times) of the CaO / γ-Al2O3 composite material (the mass ratio of the obtained calcium oxide to aluminum oxide is 8:2) prepared in Example 4, Performance Test Example 3.

[0035] Figure 9 This is a graph of the carbon dioxide capture performance (20 times) of the CaO / δ-Al2O3 composite material (the mass ratio of the obtained calcium oxide to aluminum oxide is 8:2) in Example 4, Performance Test Example 4.

[0036] Figure 10 This is a graph of the carbon dioxide capture performance (20 times) of the CaO / δ-Al2O3 composite material (the mass ratio of the obtained calcium oxide to aluminum oxide is 7:3) in Example 4, Performance Test Example 5.

[0037] Figure 11 This is a graph of the carbon dioxide capture performance (20 times) of the CaO / δ-Al2O3 composite material (the mass ratio of the obtained calcium oxide to aluminum oxide is 9:1) in Performance Test Example 6 of Example 4.

[0038] Figure 12 4 is a scanning electron microscope image of the CaO / δ-Al2O3 composite material in performance test example 4 (the mass ratio of the obtained calcium oxide to aluminum oxide is 8:2). DETAILED DESCRIPTION

[0039] On one hand, embodiments of the present invention provide a calcium-aluminum-based composite material comprising CaO and x-Al2O3. The x-Al2O3 serves as a structural support material for the CaO, further enhancing the stability of the material during repeated carbon dioxide capture. This addresses a gap in existing research and technology, which has not yet compared the stabilizing effects of different phases of aluminum oxide on CaO during carbon dioxide capture. Another embodiment of the present invention provides a method for preparing the aforementioned calcium-aluminum-based composite material.

[0040] In order to better understand the above technical solution, the above technical solution will be described in detail below in conjunction with specific embodiments.

[0041] Example 1

[0042] This embodiment provides a method for preparing x-Al2O3:

[0043] The x-Al2O3 in the present invention includes γ-, α- and δ-Al2O3. The specific preparation methods of α- and δ-Al2O3 are as follows:

[0044] S1: Commercial γ-Al2O3 (particle size less than or equal to 1 micron) is sintered at 1200℃ to produce α-Al2O3;

[0045] S2: Commercial γ-Al2O3 is sintered at 900℃ to produce δ-Al2O3;

[0046] from Figure 1 It can be seen from the XRD patterns of Al2O3 with different phases prepared.

[0047] The sintering program at a sintering temperature of 1200° C. in S1 is 0-500° C., 5° C. / min, 500-800° C., 10° C. / min, 800-1200° C., 5° C. / min, and holding time is 2 h.

[0048] The sintering program at a sintering temperature of 900° C. in S2 is 0-500° C., 5° C. / min, 500-800° C., 10° C. / min, 800-900° C., 5° C. / min, and heat preservation for 2 h.

[0049] Example 2

[0050] This example provides a method for preparing pure CaO material, the steps comprising:

[0051] S1: Calcium acetate is placed in a tube furnace and burned at high temperature to obtain pure CaO material. Figure 2 is the XRD pattern of pure CaO material;

[0052] The sintering temperature in S1 is 900° C., and the sintering program is 0-500° C., 5° C. / min, 500-800° C., 10° C. / min, 800-900° C., 5° C. / min, and holding time is 2 h.

[0053] Example 3

[0054] This example provides a method for preparing a calcium-aluminum-based composite material, the steps comprising:

[0055] S1: Commercial γ-Al2O3 is sintered at high temperature to prepare α- and δ-Al2O3. The sintering system is carried out according to the corresponding steps in Example 1.

[0056] S2: ball milling γ-Al2O3 and calcium acetate precursor to mix evenly, and sintering at high temperature to obtain CaO@γ-Al2O3 composite material; Figure 3The XRD pattern of S2 is shown in Figure 2. In this S2, gamma-alumina reacts with calcium oxide to form calcium aluminate. When it coexists with calcium oxide, there is no gamma-to-delta phase transition.

[0057] S3: The δ-Al2O3 and α-Al2O prepared in step S1 are respectively ball-milled and mixed with the calcium acetate precursor, and then sintered at high temperature to obtain CaO@δ-Al2O3 and CaO@α-Al2O3 composite materials, such as Figure 4 and Figure 5 As shown in the XRD pattern.

[0058] In step S1, the sintering temperature for γ-Al2O3 to transform into α-Al2O3 is 1200°C for 2h, and the sintering temperature for γ-Al2O3 to transform into δ-Al2O3 is 900°C.

[0059] In step S2, the ball milling condition is 800 r / min, the ball milling time is 6 h, and the ball-to-material mass ratio is 8:1.

[0060] In step S2, the mass ratio of calcium oxide prepared from calcium acetate to aluminum oxide is 7-9:3-1.

[0061] In step S2, the high-temperature sintering temperature is 900°C, the sintering program is 0-500°C, 5°C / min, 500-800°C, 10°C / min, 800-900°C, 5°C / min, and the heat preservation is 2h.

[0062] In step S3, the ball milling conditions and high-temperature sintering conditions are the same as those in step S2; in step S3, the mass ratio of CaO prepared from calcium acetate to alumina is 7-9:3-1.

[0063] Example 4

[0064] This example provides a method for testing the CO2 capture performance of calcium-aluminum-based composite materials, including the following steps:

[0065] S1: Take about 10 mg of each of the CaO@γ-Al2O3, CaO@δ-Al2O3 and CaO@α-Al2O3 composite materials in steps S2 and S3 of Example 3 and place them in a platinum crucible.

[0066] S2: The test procedure is designed to raise the temperature from room temperature to 900℃ and keep it at this temperature for 5 minutes.

[0067] Performance test example 1

[0068] Testing calcium-aluminum-based composites for carbon dioxide capture:

[0069] 10.11 mg of pure CaO material (precursor calcium acetate) obtained in step S1 of Example 2 was weighed and placed in a platinum crucible compatible with a thermogravimetric analyzer to test the CO2 capture performance of the pure CaO material.

[0070] like Figure 6 As shown, the initial carbon dioxide capture capacity of pure CaO is 0.70g CO2 / g adsorbent. After 20 cycles, the carbon dioxide capture capacity is 0.11g CO2 / g adsorbent, the cycle retention rate is 16%, and the capture capacity decays seriously.

[0071] Performance test example 2

[0072] Weigh 10.63 mg of the CaO@α-Al2O3 composite material prepared in step S3 of Example 3 (the mass ratio of the prepared calcium oxide to aluminum oxide is 8:2) and place it in a platinum crucible compatible with a thermogravimetric analyzer to test the CO2 capture performance of the composite material.

[0073] The carbon dioxide capture performance and cycle performance of the calcium-aluminum-based composite material of this example are shown in FIG. Figure 7 As shown, from Figure 7 As can be seen from the graph, the initial carbon dioxide capture capacity of the CaO@α-Al2O3 composite material is 0.57g CO2 / g adsorbent. After 20 cycles, the carbon dioxide capture capacity is 0.33g CO2 / g adsorbent, and the cycle retention rate is 57.9%. It can be seen that the carbon dioxide capture performance of the CaO@α-Al2O3 composite material prepared by ball milling and sintering in the embodiment of the present invention is improved compared with the pure CaO material. Figure 8 , as shown in the CO2 capture performance test diagram of CaO@α-Al2O3 composite material.

[0074] Performance test example 3

[0075] Weigh 9.77 mg of the CaO@γ-Al2O3 composite material prepared in step S3 of Example 3 (the mass ratio of the prepared calcium oxide to aluminum oxide is 8:2) and place it in a platinum crucible compatible with a thermogravimetric analyzer to test the CO2 capture performance of the composite material.

[0076] The cyclic capture performance of carbon dioxide by the CaO@γ-Al2O3 composite material in Example 3 was tested. Figure 8 As shown, from Figure 8 As can be seen from the graph, the initial carbon dioxide capture capacity of the CaO@γ-Al2O3 composite material is 0.54g CO2 / g adsorbent. After 20 cycles, the carbon dioxide capture capacity is 0.37g CO2 / g adsorbent, and the cycle retention rate is 68.5%. It can be seen that the carbon dioxide capture performance of the CaO@γ-Al2O3 composite material prepared by ball milling and sintering in the embodiment of the present invention is improved compared with that of pure CaO material, and is better than that of the CaO@α-Al2O3 composite material. Figure 8, as shown in the CO2 capture performance test diagram of CaO@γ-Al2O3 composite material.

[0077] Performance test example 4

[0078] 11.12 mg of the CaO@δ-Al2O3 composite material prepared in step S3 of Example 3 (the mass ratio of the prepared calcium oxide to aluminum oxide is 8:2) was weighed and placed in a platinum crucible compatible with a thermogravimetric analyzer to test the CO2 capture performance of the composite material.

[0079] The carbon dioxide capture performance of the CaO@δ-Al2O3 composite material in Example 3 was tested, and the cycle performance was as follows: Figure 9 As shown, from Figure 9 As can be seen from the graph, the initial carbon dioxide capture capacity of the CaO@δ-Al2O3 composite material is 0.52g CO2 / g adsorbent. After 20 cycles, the carbon dioxide capture capacity is 0.46g CO2 / g adsorbent, and the cycle retention rate is 88.5%. It can be seen that the carbon dioxide capture performance of the CaO@δ-Al2O3 composite material prepared by ball milling and sintering in the embodiment of the present invention is improved compared with that of pure CaO material, and is better than that of CaO@α-Al2O3 and CaO@γ-Al2O3 composite materials. Figure 9 , as shown in the CO2 capture performance test diagram of CaO@δ-Al2O3 composite material.

[0080] Performance test example 5

[0081] 10.07 mg of the CaO@δ-Al2O3 composite material prepared in step S3 of Example 3 (the mass ratio of the prepared calcium oxide to aluminum oxide is 7:3) was weighed and placed in a platinum crucible compatible with a thermogravimetric analyzer to test the CO2 capture performance of the composite material.

[0082] The carbon dioxide capture performance of the CaO@δ-Al2O3 composite material in Example 3 was tested, and the cycle performance was as follows: Figure 10 As shown, from Figure 10 As can be seen from the graph, the initial carbon dioxide capture capacity of the CaO@δ-Al2O3 composite material is 0.46g CO2 / g adsorbent. After 20 cycles, the carbon dioxide capture capacity is 0.40g CO2 / g adsorbent, and the cycle retention rate is 87.0%. It can be seen that the carbon dioxide capture performance of the CaO@δ-Al2O3 composite material prepared by ball milling and sintering in the embodiment of the present invention is improved compared with that of pure CaO material, and is better than that of CaO@α-Al2O3 and CaO@γ-Al2O3 composite materials. Figure 10 , as shown in the CO2 capture performance test diagram of CaO@δ-Al2O3 composite material.

[0083] Performance test example 6

[0084] 10.63 mg of the CaO@δ-Al2O3 composite material prepared in step S3 of Example 3 (the mass ratio of the prepared calcium oxide to aluminum oxide is 9:1) was weighed and placed in a platinum crucible compatible with a thermogravimetric analyzer to test the CO2 capture performance of the composite material.

[0085] The carbon dioxide capture performance of the CaO@δ-Al2O3 composite material in Example 3 was tested, and the cycle performance was as follows: Figure 11 As shown, from Figure 11 As can be seen from the graph, the initial carbon dioxide capture capacity of the CaO@δ-Al2O3 composite material is 0.58g CO2 / g adsorbent. After 20 cycles, the carbon dioxide capture capacity is 0.41g CO2 / g adsorbent, and the cycle retention rate is 70.7%. It can be seen that the carbon dioxide capture performance of the CaO@δ-Al2O3 composite material prepared by ball milling and sintering in the embodiment of the present invention is improved compared with that of pure CaO material, and is superior to that of CaO@α-Al2O3 and CaO@γ-Al2O3 composite materials. Figure 11 , as shown in the CO2 capture performance test diagram of CaO@δ-Al2O3 composite material.

[0086] By manipulating the transformation of Al2O3 into different phases through high-temperature sintering and combining it with calcium oxide, the CO2 capture performance of the CaO / alumina composite was further modified. The CaO@δ-Al2O3 composite exhibited excellent CO2 capture performance. The initial CO2 capture capacity of the CaO@δ-Al2O3 composite was 0.52g CO2 / g adsorbent. After 20 cycles, the CO2 capture capacity reached 0.46g CO2 / g adsorbent, with a cycle retention rate of 88.5%.

[0087] The above description is only a preferred embodiment of the present invention and does not limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A calcium-aluminum-based composite material, characterized in that: The composite material includes δ-Al2O3 and CaO; the composite material is obtained by mixing a CaO precursor and δ-Al2O3 and then calcining; the mass ratio of the precursor to δ-Al2O3 is 7-9:3-1; The particle size of the γ-Al2O3 used is less than or equal to 1 μm, and the δ-Al2O3 used is obtained by high-temperature sintering of γ-Al2O3; the high-temperature sintering temperature is 900°C; In the composite material, the mass ratio of CaO to δ-Al2O3 is 7.5-8.5:1.5-2.5; The preparation method of the calcium-aluminum-based composite material is as follows: Weigh the raw materials according to the designed composition ratio, mix them evenly, and then sinter them at a high temperature of 900°C to obtain a composite material; The high-temperature sintering temperature is 900°C, and the sintering program is 0-500°C, 5°C / min, 500-800°C, 10°C / min, 800-900°C, 5°C / min, and holding time is 2 h.

2. A calcium-aluminum-based composite material according to claim 1, characterized in that: The precursor used is at least one selected from calcium acetate, calcium carbonate and calcium nitrate.

3. The calcium-aluminum-based composite material according to claim 1, characterized in that: The mixture was mixed evenly by ball milling, the speed was controlled at 600-800 r / min, and the ball milling time was 4-8h.

4. The calcium-aluminum-based composite material according to claim 1, characterized in that: In the obtained calcium-aluminum-based composite material, the mass ratio of calcium oxide to aluminum oxide is 8:

2. The initial carbon dioxide capture capacity is 0.52 g CO2 / g adsorbent. After 20 cycles, the CO2 capture capacity is 0.46 g CO2 / g adsorbent, and the cycle retention rate is 88.5%.

Images