Preparation method of mesoporous nano-β-Bi2O3 and its application in direct air capture of CO2

Abstract

The present invention relates to the technical field of carbon dioxide capture, and particularly to a preparation method of mesoporous nano-β-Bi2O3 and its application in direct air capture of CO2. The preparation of mesoporous nano-β-Bi2O3 includes the following steps: A. Mix bismuth acetate solution and citric acid to obtain a first solution, and prepare a sodium hydroxide solution without carbon dioxide; B. Mix the first solution and the sodium hydroxide solution, let it stand, filter by suction, wash, dry and calcine to obtain mesoporous nano-β-Bi2O3; The nano-β-Bi2O3 directly captures CO2 in the air and is converted into Bi2O2CO3 through a chemical reaction, and then the adsorption and desorption recycling of CO2 are realized through the decomposition of Bi2O2CO3, and the product gas concentration is greater than 90%. The prepared β-Bi2O3 of the present invention has the advantages of stable physical and chemical properties, greenness, no solvent loss, wide sources of raw materials, etc. At the same time, the present invention can also be used for the synthesis of Bi2O2CO3. The present invention provides a method for preparing nano-β-Bi2O3 and using it for direct air capture of CO2, providing a new way for the direct air capture of CO2 technology.

Description

Technical Field

[0001] The present invention relates to the technical field of carbon dioxide capture, and in particular to a preparation method of mesoporous nano-β-Bi2O3 and its application in direct air capture of CO2. Background Art

[0002] At present, the methods that can effectively achieve carbon capture are divided into CCS technology for fixed emission sources and direct air capture DAC technology. Compared with CCS technology, DAC technology has a lower concentration of captured CO2, so it requires higher energy consumption and cost. Since Professor Lackner proposed DAC technology in 1999, its development has been in its early stages for more than 20 years. The comparison between DAC technology and CCS (carbon capture and storage) technology is shown in Table 1.

[0003] Table 1 Comparison between DAC technology and CCS (carbon capture and storage) technology

[0004]

[0005] At present, DAC technology includes alkaline hydroxide solution DAC technology, amine solution DAC technology, amino acid solution / BIGs technology, solid amine adsorbent DAC technology, MOFs material DAC technology, and variable humidity adsorption technology. The DAC technology currently used on a large scale in industry is mainly alkaline hydroxide DAC technology, which absorbs CO2 through KOH or NaOH and converts it into Na2CO3, then adds Ca(OH)2 to generate precipitated CaCO3, and finally decomposes at high temperature to produce CO2 and CaO. In the entire DAC technology, the adsorbent can be recycled. The advantages and disadvantages of various DAC technologies are shown in Table 2.

[0006] Table 2 Comparison of various DAC technologies

[0007] Summary of the invention

[0008] In order to solve the above technical problems, the embodiments of the present invention provide a method for preparing mesoporous nano-β-Bi2O3 and its application in direct air capture of CO2 to achieve the capture of carbon dioxide.

[0009] To achieve the above object, the embodiments of the present invention adopt the following technical solutions:

[0010] In one aspect, the present invention provides a method for preparing mesoporous nano-β-Bi2O3, comprising the following steps:

[0011] A. mixing bismuth acetate solution and citric acid to obtain a first solution, and preparing a sodium hydroxide solution without carbon dioxide;

[0012] B. Mix the first solution and the sodium hydroxide solution, let stand, filter, wash, dry and calcine to obtain mesoporous nano-β-Bi2O3.

[0013] In some embodiments, in step A, the mixing temperature of the bismuth acetate solution and citric acid is 80°C.

[0014] In some embodiments, in step A, the concentration of the bismuth acetate solution is 0.1 mol / L to 1 mol / L.

[0015] In some embodiments, in step A, the concentration of citric acid is 0.2 mol / L to 1 mol / L.

[0016] In some embodiments, in step A, the concentration of the sodium hydroxide solution is 0.1 mol / L to 1 mol / L.

[0017] In some embodiments, in step B, the volume ratio of the first solution to the sodium hydroxide solution is 1:1.

[0018] In some embodiments, in step B, the drying temperature is 60° C. and the drying time is 1 hour.

[0019] In some embodiments, in step B, the calcination temperature is 380° C., and the calcination time is 1 h.

[0020] On the other hand, the present invention provides an application of mesoporous nano-β-Bi2O3 prepared by the above-mentioned preparation method in direct air capture of CO2, as follows:

[0021] Place mesoporous nano-β-Bi2O3 in the capture device, inject deionized water into the device at a mass ratio of 1:500 between mesoporous nano-β-Bi2O3 and deionized water, turn on the air compressor, set the flow meter flow rate to 150mL / min, and pass air into the capture device. Stir at 300rpm and add aeration devices during the ventilation process to make the air fully contact with the mesoporous nano-β-Bi2O3, and detect the CO2 concentration in the air after adsorption at the outlet. Stop adsorption when the CO2 at the outlet is consistent with the air. Open the valve to discharge the water, open the Ar gas cylinder, discharge the air in the reaction chamber, and detect CO2 at the outlet with an infrared CO2 analyzer, and analyze the CO2 content with a gas chromatograph. When the outlet concentration is zero, close the inlet and outlet valves. The temperature of the device was raised to 450°C and kept warm for 3 hours. The CO2 produced by the decomposition was collected in a gas storage tank, and the CO2 concentration at the outlet was detected. When there was no carbon dioxide at the outlet, the desorption was completed. The mesoporous nano-β-Bi2O3 was used to directly capture CO2 from the air. The CO2 capture amount was 1.99 mmol / g, and the product gas concentration was greater than 90%.

[0022] The process of capturing CO2 by mesoporous nano-β-Bi2O3 of the present invention includes two parts. The first step is to convert CO2 in the air into Bi2O2CO3: CO2(g)+Bi2O3(s)→Bi2O2CO3(s). The second step is to directly heat the Bi2O2CO3 solution to 450°C in the reaction chamber for decomposition after the water in the solution is discharged, and the decomposition reaction is: Bi2O2CO3(s)→CO2(g)+Bi2O3(s).

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] (1) The reaction conditions for preparing mesoporous nano-β-Bi2O3 in the present invention are relatively mild and the product purity is high.

[0025] (2) The preparation of mesoporous nano-β-Bi2O3 by the present invention produces fewer by-products and wastes, is easy to handle, reduces environmental pollution, and complies with the development trend of green chemistry.

[0026] (3) The present invention uses mesoporous nano-β-Bi2O3 to directly capture CO2 from air. Compared with other capture technologies, the capture process of the present invention can be adsorbed at room temperature and pressure, with no pollution, no solvent loss, no corrosion to equipment, high adsorption capacity, and excellent cyclic capture performance.

[0027] (4) The mesoporous nano-β-Bi2O3 of the present invention can be recycled in the adsorption and desorption process of direct air capture of CO2, and has excellent recycling performance. The direct air capture of CO2 concentration is greater than 90%, and the CO2 capture amount is 1.99mmol g -1 . BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is the X-ray diffraction analysis spectrum of β-Bi2O3 prepared in Example 1 of the present invention;

[0029] Figure 2 This is an electron scanning microscope image of β-Bi2O3 prepared in Example 1 of the present invention;

[0030] Figure 3 is the isothermal adsorption curve of β-Bi2O3 prepared in Example 1 of the present invention;

[0031] Figure 4 This is the SEM analysis spectrum of the CO2 adsorption process of β-Bi2O3 directly captured in air prepared in Example 1 of the present invention;

[0032] Figure 5 The XRD analysis spectrum of the CO2 adsorption process of β-Bi2O3 directly captured in air prepared in Example 1 of the present invention;

[0033] Figure 6The XRD analysis spectrum of the product of the direct CO2 capture and desorption process of β-Bi2O3 in air prepared in Example 1 of the present invention;

[0034] Figure 7 This is the TG diagram of the CO2 capture and desorption process of β-Bi2O3 directly in air prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0035] The following will be combined with the accompanying drawings to clearly and completely describe the technical solutions in some embodiments of the present disclosure. Obviously, the described embodiments are only part of the embodiments of the present disclosure, rather than all the embodiments. Based on the embodiments provided by the present disclosure, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the present disclosure.

[0036] Example 1

[0037] (1) 0.1 mol of bismuth acetate powder was added to 1 L of deionized water, and 6 mL of 0.5 mol / L citric acid was added to form a mixed solution, which was magnetically stirred for 1 h and ultrasonically vibrated for 1 h;

[0038] (2) adding sodium hydroxide with a concentration of 0.1 mol / L to the solution in step (1), stirring magnetically for 1 hour, and standing for 24 hours. The volume ratio of bismuth acetate solution to sodium hydroxide is 1:1;

[0039] (3) The mixed solution in step (2) was stirred at 200 rpm for 1 hour, then allowed to stand for 24 hours and filtered, and the obtained precipitate was repeatedly rinsed with deionized water and then dried at 60° C. for 1 hour;

[0040] (4) placing the precipitate in step (3) in a high temperature decomposition furnace, heating to 380° C. and calcining for 1 h to obtain yellow solid bismuth oxide.

[0041] The XRD analysis diagram of β-Bi2O3 prepared in Example 1 is as follows Figure 1 As shown in the scanning electron microscope image Figure 2 As shown by Figure 1 Compared with the XRD spectrum of commercial bismuth oxide, the product prepared by the present invention is β-Bi2O3; Figure 2 The SEM image shows that the β-Bi2O3 prepared by the present invention is in block form, and its N2 isotherm adsorption curve is as follows: Figure 3 As shown, it can be concluded through BJH calculation that the pore size of β-Bi2O3 prepared by the present invention is 20-50nm, with a large specific surface area and pore size, which is conducive to the adsorption of bismuth oxide and CO2.

[0042] Example 2: A preparation method of β-Bi2O3 for direct air capture of CO2, the specific steps are:

[0043] (1) 0.2 mol of commercial bismuth acetate powder was added to 500 mL of deionized water, and 6 mL of 0.5 mol / L citric acid was added to form a mixed solution, which was magnetically stirred for 1 h and ultrasonically vibrated for 1 h;

[0044] (2) adding 0.2 mol / L sodium hydroxide to the solution in step (1), stirring magnetically for 1 hour, and standing for 24 hours. The volume ratio of bismuth acetate solution to sodium hydroxide is 1:1;

[0045] (3) The mixed solution in step (2) was stirred at 800 rpm for 1 hour, then allowed to stand for 24 hours and filtered, and the obtained precipitate was repeatedly rinsed with deionized water and then dried at 60° C. for 1 hour;

[0046] (4) placing the precipitate in step (3) in a high temperature decomposition furnace, heating to 380° C. and calcining for 1 h to obtain yellow solid bismuth oxide.

[0047] Test example

[0048] The β-Bi2O3 prepared by the method of Example 1 is used to capture CO2 directly from air. The specific steps are:

[0049] (1) Take 1 g of β-Bi2O3 prepared in Example 1 and put it into a capture device, and inject 500 mL of deionized water into the device.

[0050] (2) Turn on the air compressor, set the flow meter flow rate to 150mL / min, and pass air into the capture device. During the ventilation process, stirring and adding aeration devices are required to allow the air to fully contact with β-Bi2O3, and detect the CO2 concentration in the air after adsorption at the tail end. Stop the adsorption when the CO2 concentration at the outlet is consistent with that of the air. The SEM image of the product after adsorption is shown in Figure 2. Figure 4 As shown, combined Figure 2 It can be found that as the reaction proceeds, the blocky bismuth oxide is gradually transformed into a flake product, and the XRD pattern of the sample after adsorption is completed (i.e. Figure 5 ) was compared with the XRD pattern of commercial Bi2O2CO3, and it was determined that the adsorbed product was Bi2O2CO3. It was thus inferred that the chemical reaction involved in the adsorption of CO2 by bismuth oxide is: CO2(g)+Bi2O3(s)→Bi2O2CO3(s).

[0051] (3) After the adsorption is completed, open the valve to discharge the water. At the same time, open the Ar gas cylinder and continuously introduce Ar into the reaction chamber to exhaust the air in the reaction chamber. Detect CO2 at the outlet. When there is no CO2 at the outlet, close the inlet and outlet valves.

[0052] (4) Turn on the heating device and raise the temperature to 450°C, keep it warm for 3 hours, use a chromatographic needle to sample and analyze the amount of CO2 decomposition, and use a CO2 analyzer to detect the concentration of CO2 produced by decomposition. The XRD pattern of the solid product after desorption is shown in Figure 6 As shown, it was found that it was consistent with the XRD of β-Bi2O3 before adsorption, so it was judged that the solid product after desorption was β-Bi2O3, and the reaction involved in the desorption process was: Bi2O2CO3(s)→CO2(g)+Bi2O3(s).

[0053] (5) Results: The carbon dioxide capture process of Example 1 was completed by adsorption after air was introduced at room temperature. After decomposition, the captured amount of CO2 in the product gas was 1.99 mmol g -1 , Figure 7 This is the TG diagram of the synthesized Bi2O2CO3. The decomposition amount of the product gas CO2 is 2.02mmol g according to the loss of decomposition products in the thermogravimetric curve. -1， , basically the same. Detected by CO2 analyzer, the CO2 concentration of the product gas is> 90%.

[0054] In the description of this specification, specific features, structures, materials or characteristics may be combined in an appropriate manner in any one or more embodiments or examples.

[0055] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for preparing mesoporous nano-β-Bi2O3, characterized in that: The following steps are involved: A. mixing bismuth acetate solution and citric acid to obtain a first solution, and preparing a sodium hydroxide solution without carbon dioxide; B. Mixing the first solution and the sodium hydroxide solution, standing, filtering, washing, drying and calcining to obtain mesoporous nano-β-Bi2O3; the calcination temperature is 380° C., and the calcination time is 1 hour; In step A, the mixing temperature of the bismuth acetate solution and citric acid is 80° C.; In step A, the concentration of the bismuth acetate solution is 0.1 mol / L to 1 mol / L; In step A, the concentration of citric acid is 0.2 mol / L to 1 mol / L; In step A, the concentration of the sodium hydroxide solution is 0.1 mol / L to 1 mol / L; In step B, the volume ratio of the first solution to the sodium hydroxide solution is 1:1; In step B, the drying temperature is 60° C. and the drying time is 1 hour.

2. Application of mesoporous nano-β-Bi2O3 prepared by the preparation method as claimed in claim 1 in direct air capture of CO2.

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