Calcium-based carbon dioxide adsorbent and method of making and using same

Abstract

This application discloses a calcium-based carbon dioxide adsorbent, its preparation method, and its application, relating to the field of adsorbent technology. The preparation method of the calcium-based carbon dioxide adsorbent includes the following steps: obtaining calcium hydroxide, an unsaturated organic compound, magnesium oxide, and aluminum oxide; mixing the calcium hydroxide, unsaturated organic compound, magnesium oxide, and aluminum oxide and adding them to a solvent; heating and stirring to obtain a mixed suspension, wherein the unsaturated organic compound is an organic acid or an organic aldehyde; drying the mixed suspension to obtain a dried powder; subjecting the dried powder to medium-temperature combustion to obtain a calcium-based carbon dioxide adsorbent precursor, wherein the medium-temperature combustion temperature is 400–600°C; and subjecting the calcium-based carbon dioxide adsorbent precursor to a first high-temperature calcination to obtain the calcium-based carbon dioxide adsorbent, wherein the first high-temperature calcination temperature is 700–1000°C. This application solves the technical problem of poor adsorption performance of existing calcium-based carbon dioxide adsorbents.

Description

Technical Field

[0001] This application relates to the field of adsorbent technology, and in particular to a calcium-based carbon dioxide adsorbent, its preparation method, and its application. Background Technology

[0002] In recent years, with the massive consumption of fossil fuels and the impact of human activities, the production of greenhouse gases, especially carbon dioxide, has increased significantly. Climate change has become one of the most severe challenges facing human sustainable development, making carbon dioxide emission reduction a crucial task in the field of environmental protection. Currently, my country's main sources of carbon dioxide emissions are concentrated in the power and industrial production sectors (such as flue gas emissions from coal-fired power plants) and the transportation sector (such as exhaust emissions from mobile sources like ships and automobiles). Among these, the transportation industry is a vital sector supporting national economic development and also one of the fastest-growing sectors in terms of energy consumption and carbon emissions, accounting for approximately 10% of the country's total carbon emissions. In the near future, this proportion will further increase with the continued growth in transportation demand.

[0003] Among current carbon dioxide capture technologies, post-combustion carbon dioxide capture technology is more suitable for capturing carbon dioxide from vehicle exhaust. Calcium-based carbon dioxide adsorbents have many advantages, such as: wide availability and abundant natural reserves (e.g., limestone, dolomite), low cost, non-toxicity, high operating temperature (600-700℃), fast reaction kinetics, and high theoretical adsorption capacity (0.786g carbon dioxide / g adsorbent). However, the adsorption performance of calcium-based carbon dioxide adsorbents prepared in related technologies is relatively poor; their capture performance declines rapidly during use, and they may even become inactive, resulting in a short service life. Summary of the Invention

[0004] The main objective of this application is to provide a calcium-based carbon dioxide adsorbent, its preparation method, and its application, aiming to solve the technical problem of poor adsorption performance of existing calcium-based carbon dioxide adsorbents.

[0005] To achieve the above objectives, this application provides a method for preparing a calcium-based carbon dioxide adsorbent, the method comprising the following steps:

[0006] Calcium hydroxide, unsaturated organic compounds, magnesium oxide, and aluminum oxide are obtained. The calcium hydroxide, unsaturated organic compounds, magnesium oxide, and aluminum oxide are mixed and added to a solvent. The mixture is heated and stirred to obtain a mixed suspension. The unsaturated organic compounds are organic acids or organic aldehydes.

[0007] The mixed suspension was dried to obtain dried powder.

[0008] The dried powder is subjected to medium-temperature combustion to obtain a calcium-based carbon dioxide adsorbent precursor, wherein the medium-temperature combustion temperature is 400-600℃.

[0009] The calcium-based carbon dioxide adsorbent precursor is subjected to a first high-temperature calcination to obtain the calcium-based carbon dioxide adsorbent, wherein the temperature of the first high-temperature calcination is 700-1000℃.

[0010] The step of subjecting the calcium-based carbon dioxide adsorbent precursor to a first high-temperature calcination to obtain the calcium-based carbon dioxide adsorbent includes:

[0011] The calcium-based carbon dioxide adsorbent precursor was subjected to a first high-temperature calcination to obtain calcium-based carbon dioxide adsorbent powder.

[0012] The calcium-based carbon dioxide adsorbent powder is mixed with a binder and a solvent, and the mixture is granulated to form mixture particles;

[0013] The mixture particles are subjected to a second high-temperature calcination to obtain granular calcium-based carbon dioxide adsorbent, wherein the temperature of the first high-temperature calcination is 700-1000℃.

[0014] Optionally, the adhesive comprises at least one of polyvinylpyrrolidone and hydroxypropyl methylcellulose;

[0015] And / or, the amount of the adhesive added is 2 to 5% of the mass of the calcium-based carbon dioxide adsorbent powder;

[0016] And / or, the amount of solvent added is 40-60% of the mass of the calcium-based carbon dioxide adsorbent powder.

[0017] Optionally, the step of subjecting the mixture particles to a second high-temperature calcination to obtain granular calcium-based carbon dioxide adsorbent includes:

[0018] The mixture particles are dried at 80–110°C for 8–24 h. After drying, they are subjected to a second high-temperature calcination at 700–1000°C under nitrogen purging to obtain granular calcium-based carbon dioxide adsorbent. The second high-temperature calcination time is 60–180 min, and the nitrogen flow rate during nitrogen purging is 10–30 L / min.

[0019] Optionally, the sum of the masses of the magnesium oxide and the aluminum oxide in the calcium-based carbon dioxide adsorbent accounts for less than 19% of the total mass.

[0020] And / or, the mass ratio of the unsaturated organic compound to the calcium hydroxide is (0.6–1.2):1;

[0021] And / or, the organic acid includes citric acid;

[0022] And / or, the organic aldehyde includes glucose.

[0023] Optionally, the intermediate-temperature combustion is carried out under a first air purging, wherein the air flow rate of the first air purging is 1 to 5 L / min;

[0024] And / or, the combustion time of the medium-temperature combustion is 30 to 150 minutes.

[0025] Optionally, the first high-temperature calcination is carried out under a second air purging, wherein the air flow rate of the second air purging is 10-30 L / min;

[0026] And / or, the calcination time of the first high-temperature calcination is 60 to 180 minutes.

[0027] Optionally, the calcium-based carbon dioxide adsorbent includes calcium oxide, and also includes at least one of magnesium oxide, aluminum oxide, calcium aluminum oxide, aluminum magnesium oxide, and calcium magnesium oxide, wherein the mass percentage of calcium oxide in the calcium-based carbon dioxide adsorbent is greater than or equal to 80%.

[0028] This application also provides a calcium-based carbon dioxide adsorbent, which is prepared by the method described above.

[0029] This application also provides the calcium-based carbon dioxide adsorbent prepared by the method described above, or the application of the calcium-based carbon dioxide adsorbent described above in capturing carbon dioxide in the exhaust gas of methanol-fueled vehicles.

[0030] This application provides a calcium-based carbon dioxide adsorbent, its preparation method, and its application. The preparation method of the calcium-based carbon dioxide adsorbent includes the following steps: obtaining calcium hydroxide, an unsaturated organic compound, magnesium oxide, and aluminum oxide; mixing the calcium hydroxide, unsaturated organic compound, magnesium oxide, and aluminum oxide and adding them to a solvent; heating and stirring to obtain a mixed suspension, wherein the unsaturated organic compound is an organic acid or an organic aldehyde; drying the mixed suspension to obtain a dried powder; subjecting the dried powder to medium-temperature combustion to obtain a calcium-based carbon dioxide adsorbent precursor, wherein the medium-temperature combustion temperature is 400–600°C; and subjecting the calcium-based carbon dioxide adsorbent precursor to a first high-temperature calcination to obtain the calcium-based carbon dioxide adsorbent, wherein the first high-temperature calcination temperature is 700–1000°C. First, calcium hydroxide reacts with organic acids or organic aldehydes to form calcium organic acid. This calcium organic acid decomposes during subsequent high-temperature calcination, forming carbon dioxide and water vapor that flow out from the matrix. This results in a large number of porous structures on the surface and inside the calcium-based carbon dioxide adsorbent, increasing the contact area between the adsorbent and carbon dioxide during subsequent use, thus significantly improving the capture rate. Second, by adding magnesium oxide and aluminum oxide, two inert metal oxides with high stability during the preparation and use of calcium-based carbon dioxide adsorbents, a spinel-structured calcium-based carbon dioxide adsorbent can be formed. Magnesium oxide and aluminum oxide act as an atomic framework in the adsorbent, effectively blocking calcium particles, delaying sintering, and improving the cycle stability. Third, during medium-temperature combustion and high-temperature calcination, magnesium oxide, aluminum oxide, and calcium hydroxide can form a metal composite oxide, effectively improving the mechanical properties of the calcium-based carbon dioxide adsorbent, resulting in higher particle strength and wear resistance. Fourth, the preparation method provided in this application is simple, has a short preparation cycle, and uses safe and controllable raw materials. Therefore, this invention overcomes the technical shortcomings of calcium-based carbon dioxide adsorbents prepared in related technologies, such as poor adsorption performance, rapid decline in capture performance or even deactivation during use, and short service life. By improving the raw material composition and preparation method, this invention can simply and efficiently prepare calcium-based carbon dioxide adsorbents that are more resistant to sintering, have higher cycle stability, and possess superior mechanical properties. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0032] Figure 1 This is a schematic flowchart of an embodiment of the preparation method of the calcium-based carbon dioxide adsorbent of the present invention;

[0033] Figure 2 The infrared spectrum of Example 1 in this application;

[0034] Figure 3 The infrared spectrum of Example 2 in this application;

[0035] Figure 4 The infrared spectrum of Example 3 in this application;

[0036] Figure 5 The infrared spectrum of Example 4 in this application;

[0037] Figure 6 The curves showing the change of carbon dioxide adsorption capacity over time in Example 1 and the comparative example of this application during the first cycle are shown.

[0038] Figure 7 The curves showing the change of carbon dioxide adsorption capacity over time in Example 2 and the comparative example of this application during the first cycle are shown.

[0039] Figure 8 The curves showing the change of carbon dioxide adsorption capacity over time in Example 3 and the comparative example of this application during the first cycle are shown.

[0040] Figure 9 The curves showing the change of carbon dioxide adsorption capacity over time in Example 4 and the comparative example of this application during the first cycle are shown.

[0041] Figure 10 The curves showing the change of carbon dioxide adsorption capacity with the number of cycles in Example 1 and the comparative example of this application are shown.

[0042] Figure 11 The curves showing the change of carbon dioxide adsorption capacity with the number of cycles in Example 2 and the comparative example of this application are shown.

[0043] Figure 12 The curves showing the change of carbon dioxide adsorption capacity with the number of cycles in Example 3 and the comparative example of this application are shown.

[0044] Figure 13 The graphs show the change in carbon dioxide adsorption capacity as a function of cycle number for Examples 4 and the comparative examples in this application.

[0045] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0046] To make the above-mentioned objectives, features, and advantages of the present invention more apparent and understandable, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0047] This application provides a method for preparing a calcium-based carbon dioxide adsorbent, referring to... Figure 1 The preparation method of the calcium-based carbon dioxide adsorbent includes the following steps:

[0048] Step S10: Obtain calcium hydroxide, unsaturated organic compound, magnesium oxide and aluminum oxide. Mix calcium hydroxide, unsaturated organic compound, magnesium oxide and aluminum oxide and add to solvent. Heat and stir to obtain a mixed suspension. The unsaturated organic compound is an organic acid or an organic aldehyde.

[0049] In this embodiment, it should be noted that calcium-based carbon dioxide adsorbents possess numerous advantages, such as: wide availability and abundant natural reserves (e.g., limestone, dolomite); low cost; non-toxic and harmless; high operating temperature (600-700℃); fast reaction kinetics; and high theoretical adsorption capacity (0.786 g carbon dioxide / g adsorbent). The basic principle of calcium-based carbon dioxide adsorbents in capturing carbon dioxide is the reversible reaction of calcium oxide with carbon dioxide to form calcium carbonate, and its reaction equation is:

[0050]

[0051] The forward reaction, known as carbonation, proceeds rapidly within a temperature range of 600-700℃, capturing carbon dioxide to obtain clean gas suitable for emission. Calcium oxide is converted to calcium carbonate after carbonation. The reverse reaction, known as calcination, typically occurs above 900℃. During this process, calcium carbonate decomposes into calcium oxide and carbon dioxide, regenerating the calcium-based carbon dioxide adsorbent and obtaining high-concentration carbon dioxide that is easy to separate, compress, store, and utilize. The carbonation and calcination reactions cycle repeatedly, constituting the basic process of the calcium cycle (CaL).

[0052] Calcium-based carbon dioxide adsorbents in related technologies have some unavoidable problems: First, as the carbonation reaction proceeds, a calcium carbonate product layer forms on the surface of the adsorbent, clogging its pores. Carbon dioxide gas must diffuse through this product layer to continue reacting with the internal calcium oxide. This manifests as a sudden shift in the carbonation reaction from a fast-reaction, chemically controlled phase to a slower, product-layer diffusion phase, significantly reducing the carbon dioxide capture rate. Second, the Taman temperature of calcium carbonate (i.e., the temperature at which sintering occurs) is approximately 533°C, far lower than that of the calcination reaction (i.e., the temperature at which calcium dioxide is sintered). The regeneration reaction of the carbon adsorbent takes place at a temperature greater than 900℃. Therefore, after multiple calcium cycles, the sintering effect accumulates continuously, causing the adsorbent crystals or particles to aggregate, resulting in the collapse of the channels between particles, pore closure, and a decrease in the specific surface area of ​​the calcium-based carbon dioxide adsorbent. This manifests as a rapid decline in the collection performance of the calcium-based carbon dioxide adsorbent with the increase of the number of cycles. Thirdly, the mechanical properties of the calcium-based carbon dioxide adsorbent in related technologies are poor. In practical applications, it is easy to break and pulverize due to bumps, collisions, etc., resulting in the calcium-based carbon dioxide adsorbent having too small a particle size, which can easily lead to reactor blockage or even accidents.

[0053] In one feasible embodiment, the calcium-based carbon dioxide adsorbent is used to capture carbon dioxide from the exhaust gas of methanol-fueled vehicles. However, three issues affect the effectiveness of the calcium-based carbon dioxide adsorbent in on-board carbon dioxide capture devices. The first issue affects the duration for which the exhaust gas remains at a low or near-zero concentration of carbon dioxide after passing through the capture device. Because the exhaust gas from methanol-fueled vehicles flows at a relatively high velocity, and the size of on-board carbon dioxide capture devices is limited by vehicle space, the calcium-based carbon dioxide adsorbent needs to be able to rapidly capture carbon dioxide from the exhaust gas within seconds. This requires the calcium-based carbon dioxide adsorbent to have a high carbonation reaction rate and a long reaction control phase. The second issue affects the cycle life of the calcium-based carbon dioxide adsorbent product, thus impacting cost and economics. Specifically, after multiple carbon dioxide capture and adsorbent regeneration cycles, the calcium-based carbon dioxide adsorbent is prone to sintering, leading to a significant reduction in the carbon dioxide adsorption capacity per unit mass of adsorbent. To maintain the previous carbon capture effect of the capture device, it is necessary to remove the deactivated adsorbent and add fresh adsorbent. The more frequent this adsorbent replacement operation, the higher the material cost of the adsorbent. The third issue directly determines whether granular calcium-based carbon dioxide adsorbents can be used to fill reactors and capture carbon dioxide from methanol-fueled vehicle exhaust. If the particle strength is low, meaning the particles can withstand less pressure, the mass of particles that can be filled into the reactor will be small, resulting in a poorer carbon dioxide capture effect for methanol-fueled vehicle exhaust. In addition, if the particles have poor abrasion resistance, they will suffer severe wear when the methanol-fueled vehicle is bumpy during operation, leading to particle pulverization. In severe cases, this may clog the reactor pipeline and cause an accident.

[0054] Magnesium oxide and aluminum oxide exhibit high stability during the preparation and use of calcium-based carbon dioxide adsorbents, thus acting as an atomic framework to form a spinel-structured calcium-based carbon dioxide adsorbent. This has two main advantages: firstly, it effectively blocks calcium particles, improving their dispersibility and increasing the contact area between the particles and carbon dioxide gas, thereby increasing the adsorption capacity and extending the reaction control phase; secondly, the atomic framework formed by magnesium oxide and aluminum oxide effectively inhibits the aggregation of adsorbent crystals or particles, preventing pore collapse and closure, thus delaying the sintering of the calcium-based carbon dioxide adsorbent. This not only extends the reaction control phase but also slows down the rate of performance degradation after multiple calcium cycles, improving the cycle stability of the calcium-based carbon dioxide adsorbent. Furthermore, during medium-temperature combustion and high-temperature calcination, magnesium oxide and aluminum oxide can form metal composite oxides with calcium hydroxide, effectively improving the mechanical properties of the calcium-based carbon dioxide adsorbent. Particle strength and wear resistance are significantly enhanced, leading to better practicality.

[0055] Unsaturated organic compounds are organic acids or organic aldehydes that contain unsaturated carbon-oxygen bonds in their molecules and can react with calcium hydroxide to produce calcium organic acid. Organic acids include citric acid and lactic acid, while organic aldehydes include glucose.

[0056] Optionally, the sum of the masses of the magnesium oxide and the aluminum oxide in the calcium-based carbon dioxide adsorbent accounts for less than 19% of the total mass.

[0057] And / or, the mass ratio of the unsaturated organic compound to the calcium hydroxide is (0.6–1.2):1;

[0058] And / or, the organic acid includes citric acid;

[0059] And / or, the organic aldehyde includes glucose.

[0060] In this embodiment, it should be noted that the magnesium oxide and aluminum oxide act as a framework. If the amount added is too high, the proportion of the calcium-based component actually used to capture carbon dioxide in the calcium-based carbon dioxide adsorbent will be low, resulting in a lower carbon dioxide capture rate and adsorption capacity. Therefore, the total mass of the magnesium oxide and aluminum oxide in the calcium-based carbon dioxide adsorbent is determined to be less than 19%. The mass ratio of the unsaturated organic compound to the calcium hydroxide ensures that the greater the amount of calcium organic acid generated by the reaction, the better the adsorption performance of the calcium-based carbon dioxide adsorbent. Therefore, the mass ratio of the unsaturated organic compound to the calcium hydroxide is determined to be (0.6~1.2):1, for example, 0.6:1, 0.8:1, 1:1, 1.2:1, etc.

[0061] As an example, step S10 includes: weighing calcium hydroxide, unsaturated organic compound, magnesium oxide, and aluminum oxide in a certain proportion. The calcium hydroxide, unsaturated organic compound, magnesium oxide, and aluminum oxide are mixed evenly and added to a solvent. The mixture is heated and stirred simultaneously to form a viscous suspension. During the heating and stirring process, magnesium oxide and aluminum oxide are further evenly dispersed, subsequently forming a stable framework structure. At least some calcium hydroxide reacts with at least some of the unsaturated organic compound to form calcium organic acid. Calcium organic acid is evenly and alternately distributed with magnesium oxide and aluminum oxide, and can be blocked by the framework structure of magnesium oxide and aluminum oxide, thereby delaying sintering. Unreacted calcium hydroxide and unsaturated organic compound may exist. These unreacted calcium hydroxide and unsaturated organic compound can also be further evenly dispersed and can continue to react or decompose in subsequent reactions, ultimately still converting into calcium oxide and gas. The raw material ratios of calcium hydroxide, unsaturated organic compound, magnesium oxide, aluminum oxide, and solvent can be determined according to actual needs and test results; this embodiment does not impose any limitations on this. The specific process conditions for heating and stirring are sufficient to allow calcium hydroxide to react with unsaturated organic compounds to form calcium organic acid, which are similar to existing technologies. Therefore, this embodiment will not elaborate further.

[0062] For example, the step of mixing calcium hydroxide, unsaturated organic compounds, magnesium oxide, and aluminum oxide and then adding them to a solvent, heating and stirring to obtain a mixed suspension includes: weighing calcium hydroxide, unsaturated organic compounds, magnesium oxide, and aluminum oxide into container A and mixing them evenly; measuring a certain amount of deionized water into container B, the molar amount of deionized water being 30 to 40 times the molar amount of calcium hydroxide; heating container B under a constant temperature water bath at 80°C to bring the temperature of the deionized water to 70-90°C; then slowly adding the evenly mixed material from container A into container B, maintaining the constant temperature water bath at 70-90°C, and stirring at a speed of 100-150 rpm until there are no visible dry powder particles; increasing the speed to 200-300 rpm and stirring for 1 to 3 hours, allowing the water in container B to continuously evaporate, the viscosity of the material to increase, and the fluidity to decrease, until a paste with a texture close to yogurt is formed; stopping stirring and heating to obtain a mixed suspension.

[0063] Step S20: After drying the mixed suspension, dried powder is obtained;

[0064] As an example, step S20 includes drying the mixed suspension to obtain dried powder. The drying method and temperature can be determined according to actual conditions or experimental test results, and this embodiment does not impose any restrictions on them.

[0065] For example, the mixed suspension can be transferred together with the container to a forced-air drying oven, or the mixed suspension can be transferred to a flat-bottomed container, and then the flat-bottomed container can be transferred to a forced-air drying oven, where it can be dried at 110-130°C for 20-26 hours to completely evaporate the moisture and form a block material.

[0066] In one feasible embodiment, the mixed suspension will form a block material after drying. The block material can be further crushed into powder and further sieved to collect the powder with a particle size of less than 150 μm as dried powder, so as to improve the reaction rate of subsequent combustion and calcination and ensure that the subsequent combustion and calcination reaction is complete.

[0067] Step S30: The dried powder is subjected to medium-temperature combustion to obtain a calcium-based carbon dioxide adsorbent precursor, wherein the medium-temperature combustion temperature is 400-600℃.

[0068] As an example, step S30 includes: placing the dried powder in an environment of 400-600°C for medium-temperature combustion, so as to decompose the unreacted or incompletely reacted unsaturated organic compounds in the dried powder to obtain a calcium-based carbon dioxide adsorbent precursor, wherein the temperature of the medium-temperature combustion can be 400°C, 500°C, 600°C, etc.

[0069] Optionally, the intermediate-temperature combustion is carried out under a first air purging, wherein the air flow rate of the first air purging is 1 to 5 L / min;

[0070] And / or, the combustion time of the medium-temperature combustion is 30 to 150 minutes.

[0071] In this embodiment, the intermediate-temperature combustion process can be carried out under a relatively small flow rate of first air purging to ensure complete combustion and decomposition. The flow rate of the first air purging is 1 to 5 L / min, such as 1 L / min, 3 L / min, 5 L / min, etc., and the combustion time of the intermediate-temperature combustion is 30 to 150 min, such as 30 min, 60 min, 90 min, 120 min, 150 min, etc.

[0072] Step S40: The calcium-based carbon dioxide adsorbent precursor is subjected to a first high-temperature calcination to obtain the calcium-based carbon dioxide adsorbent, wherein the temperature of the first high-temperature calcination is 700-1000℃.

[0073] In this embodiment, it should be noted that organic acid calcium, unreacted calcium hydroxide, and unburned incompletely unsaturated organic compounds all decompose at temperatures of 700–1000°C, forming calcium oxide and gases such as carbon dioxide and water. Magnesium oxide and aluminum oxide may react with the calcium-based components at temperatures of 700–1000°C to form metal composite oxides, thereby effectively improving the mechanical properties of the calcium-based carbon dioxide adsorbent, resulting in higher particle strength and wear resistance. The metal composite oxide can be at least one of calcium aluminum oxide, aluminum magnesium oxide, calcium magnesium oxide, etc., such as Ca3Al2O6, Ca... 12 Al 14 O 33 MgAl2O4, etc.

[0074] Optionally, the calcium-based carbon dioxide adsorbent includes calcium oxide, and also includes at least one of magnesium oxide, aluminum oxide, calcium aluminum oxide, aluminum magnesium oxide, and calcium magnesium oxide, wherein the mass percentage of calcium oxide in the calcium-based carbon dioxide adsorbent is greater than or equal to 80%.

[0075] In this embodiment, an appropriate amount of metal oxides and metal composite oxides can improve the mechanical properties and adsorption performance of calcium-based carbon dioxide adsorbents. However, if the proportion of metal oxides and metal composite oxides is too high, the proportion of calcium oxide actually used for adsorbing carbon dioxide will be too low, which will lead to a decrease in the adsorption performance of calcium-based carbon dioxide adsorbents. Therefore, it is determined that the mass proportion of calcium oxide in the calcium-based carbon dioxide adsorbent should be greater than or equal to 80%, such as 80%, 85%, 90%, 95%, etc.

[0076] As an example, step S40 includes: raising the temperature to 700-1000℃ to subject the calcium-based carbon dioxide adsorbent precursor to a first high-temperature calcination, causing the organic acid calcium to decompose into calcium oxide and gases such as carbon dioxide and water. These gases flow out from the carbon dioxide adsorbent matrix, thereby forming a large number of pore structures on the surface and inside of the calcium-based carbon dioxide adsorbent, resulting in a calcium-based carbon dioxide adsorbent with a porous surface. These seven-pore structures can increase the contact area between the calcium-based carbon dioxide adsorbent and carbon dioxide during subsequent use, thus significantly improving the capture rate of the calcium-based carbon dioxide adsorbent. The temperature of the first high-temperature calcination can be 700℃, 800℃, 900℃, 1000℃, etc.

[0077] Optionally, the first high-temperature calcination is carried out under a second air purging, wherein the air flow rate of the second air purging is 10-30 L / min;

[0078] And / or, the calcination time of the first high-temperature calcination is 60 to 180 minutes.

[0079] In this embodiment, the first high-temperature calcination process can be carried out under a second air purging with a relatively large flow rate to ensure sufficient calcination and decomposition. The air flow rate of the second air purging is 10-30 L / min, such as 10 L / min, 20 L / min, 30 L / min, etc., and the calcination time of the first high-temperature calcination is 60-180 min, such as 60 min, 90 min, 120 min, 150 min, 180 min, etc.

[0080] Optionally, the step of subjecting the calcium-based carbon dioxide adsorbent precursor to a first high-temperature calcination to obtain the calcium-based carbon dioxide adsorbent includes:

[0081] Step S41: The calcium-based carbon dioxide adsorbent precursor is subjected to a first high-temperature calcination to obtain calcium-based carbon dioxide adsorbent powder.

[0082] Step S42: The calcium-based carbon dioxide adsorbent powder is mixed with a binder and a solvent, and the mixture is granulated to form mixture particles;

[0083] Step S43: The mixture particles are subjected to a second high-temperature calcination to obtain granular calcium-based carbon dioxide adsorbent, wherein the temperature of the first high-temperature calcination is 700-1000℃.

[0084] In this embodiment, it should be noted that the calcium-based carbon dioxide adsorbent obtained after the first high-temperature calcination has a small particle size. Direct application to carbon dioxide capture in methanol fuel vehicles can easily cause reactor blockage. Therefore, it can be made into granules through a molding and granulation process before being filled into the reactor.

[0085] The types and amounts of adhesives and solvents, as well as the specific process conditions for granulation, can be determined based on actual conditions and experimental test results; this embodiment does not impose any limitations on these aspects. For example, the molding granulation process can be extrusion granulation, rounding granulation, etc.

[0086] Optionally, the adhesive comprises at least one of polyvinylpyrrolidone and hydroxypropyl methylcellulose;

[0087] And / or, the amount of the adhesive added is 2 to 5% of the mass of the calcium-based carbon dioxide adsorbent powder, for example, 2%, 3%, 4%, 5%, etc.;

[0088] And / or, the amount of solvent added is 40% to 60% of the mass of the calcium-based carbon dioxide adsorbent powder, for example, 40%, 50%, 60%, etc.

[0089] As an example, steps S41-S43 include: raising the temperature to 700-1000℃ to subject the calcium-based carbon dioxide adsorbent precursor to a first high-temperature calcination, causing the organic acid calcium to decompose into calcium oxide and gases such as carbon dioxide and water. These gases flow out from the carbon dioxide adsorbent matrix, thereby forming a large number of porous structures on the surface and inside of the calcium-based carbon dioxide adsorbent, resulting in calcium-based carbon dioxide adsorbent powder with a porous surface; then, uniformly mixing the calcium-based carbon dioxide adsorbent powder with a certain amount of binder and solvent, and subjecting the mixture to a molding and granulation process to form granular mixture particles; the granular mixture particles can be pre-dried and then transferred to a temperature of 700-1000℃ for a second high-temperature calcination, so that the binder and other additives are fully decomposed, resulting in granular calcium-based carbon dioxide adsorbent. The temperature of the second high-temperature calcination can be 700℃, 800℃, 900℃, 1000℃, etc.

[0090] Optionally, the step of subjecting the mixture particles to a second high-temperature calcination to obtain granular calcium-based carbon dioxide adsorbent includes:

[0091] The mixture particles are dried at 80–110°C for 8–24 h. After drying, they are subjected to a second high-temperature calcination at 700–1000°C under nitrogen purging to obtain granular calcium-based carbon dioxide adsorbent. The second high-temperature calcination time is 60–180 min, and the nitrogen flow rate during nitrogen purging is 10–30 L / min.

[0092] As an example, the mixture particles can be first dried in a forced-air drying oven to allow the solvent to evaporate, thus initially forming the calcium-based carbon dioxide adsorbent. Then, it is transferred to an environment of 700–1000°C and subjected to a second high-temperature calcination under nitrogen purging to obtain granular calcium-based carbon dioxide adsorbent. Specifically, the drying temperature is 80–110°C, for example, 80°C, 90°C, 100°C, or 110°C; the drying time is 8–24 hours, for example, 8 hours, 16 hours, or 24 hours; the second high-temperature calcination temperature is 700–1000°C, for example, 700°C, 800°C, 900°C, or 1000°C; the second high-temperature calcination time is 60–180 minutes, for example, 60 minutes, 120 minutes, or 180 minutes; and the nitrogen flow rate for nitrogen purging is 10–30 L / min, for example, 10 L / min, 20 L / min, or 30 L / min.

[0093] In one feasible embodiment, the particle size of the granular calcium-based carbon dioxide adsorbent is 5-6 mm. If the particle size is too large, the adsorption performance is low and the carbon dioxide capture rate is low. If the particle size is too small, it is easy to cause reactor blockage.

[0094] In this embodiment, firstly, calcium hydroxide reacts with organic acids or organic aldehydes to form calcium organic acid. During subsequent high-temperature calcination, the calcium organic acid decomposes to form carbon dioxide and water vapor, which flow out from the matrix. This results in a large number of porous structures forming on the surface and inside the calcium-based carbon dioxide adsorbent, increasing the contact area between the adsorbent and carbon dioxide during subsequent use, thus significantly improving the capture rate. Secondly, by adding magnesium oxide and aluminum oxide, two inert metal oxides with high stability during the preparation and use of calcium-based carbon dioxide adsorbents, a spinel-structured calcium-based carbon dioxide adsorbent can be formed. Magnesium oxide and aluminum oxide act as an atomic framework in the calcium-based carbon dioxide adsorbent, effectively blocking calcium particles, delaying sintering, and improving the cycle stability of the adsorbent. Thirdly, during medium-temperature combustion and high-temperature calcination, magnesium oxide, aluminum oxide, and calcium hydroxide can form a metal composite oxide, effectively improving the mechanical properties of the calcium-based carbon dioxide adsorbent, resulting in higher particle strength and wear resistance. Fourthly, the preparation method provided in this application is simple, has a short preparation cycle, and uses safe and controllable raw materials. Therefore, this invention overcomes the technical shortcomings of calcium-based carbon dioxide adsorbents prepared in related technologies, such as poor adsorption performance, rapid decline in capture performance or even deactivation during use, and short service life. By improving the raw material composition and preparation method, this invention can simply and efficiently prepare calcium-based carbon dioxide adsorbents that are more resistant to sintering, have higher cycle stability, and possess superior mechanical properties.

[0095] Furthermore, the present invention also provides a calcium-based carbon dioxide adsorbent, which is prepared by the method described above.

[0096] The calcium-based carbon dioxide adsorbent provided by this invention is prepared using the method described above, thus solving the technical problem of poor adsorption performance of existing calcium-based carbon dioxide adsorbents. Compared with the prior art, the beneficial effects of the calcium-based carbon dioxide adsorbent provided in this invention are the same as those of the preparation method described above, and other technical features of this calcium-based carbon dioxide adsorbent are the same as those disclosed in the methods described above, and will not be repeated here.

[0097] Furthermore, the present invention also provides the application of the calcium-based carbon dioxide adsorbent prepared by the method described above, or the calcium-based carbon dioxide adsorbent described above, in capturing carbon dioxide in the exhaust gas of methanol-fueled vehicles.

[0098] The calcium-based carbon dioxide adsorbent prepared by the method described above, or the calcium-based carbon dioxide adsorbent described above, in the capture of carbon dioxide in methanol-fueled vehicle exhaust provided by this invention, solves the technical problem of poor adsorption performance of existing calcium-based carbon dioxide adsorbents. Compared with the prior art, the beneficial effects of the calcium-based carbon dioxide adsorbent provided by the embodiments of this invention in the capture of carbon dioxide in methanol-fueled vehicle exhaust are the same as the beneficial effects of the preparation method of the calcium-based carbon dioxide adsorbent provided in the above embodiments, and other technical features of the calcium-based carbon dioxide adsorbent in the capture of carbon dioxide in methanol-fueled vehicle exhaust are the same as those disclosed in the methods of the above embodiments, and will not be repeated here.

[0099] The present invention will now be described in detail with reference to specific embodiments and comparative examples. It is to be understood that the following description is merely exemplary and not intended to limit the specific scope of the invention.

[0100] Example 1

[0101] Take 296g of quicklime powder, 840g of citric acid monohydrate powder, 12.4g of magnesium oxide powder, and 12.4g of aluminum oxide powder, and mix them evenly. The resulting powder mixture will be used in the next step. Add 2.2L of deionized water to a stirred reactor and raise the temperature to 80℃. Slowly add the powder mixture obtained in the previous step to the stirred reactor and react at a stirring rate of 300r / min for 2 hours to generate a viscous suspension. Transfer the viscous suspension to a flat container and dry it in a forced-air drying oven at 110℃ for 18 hours to obtain a dried block. Use a pulverizer to crush the dried block into solid powder and sieve it to below 300 mesh. The mixture was then transferred to a medium-temperature atmosphere furnace for combustion at 400°C. The combustion process was carried out using compressed air at a rate of 3 L / min for 150 minutes. After combustion, the calcium-based carbon dioxide adsorbent precursor was transferred to a high-temperature atmosphere furnace for high-temperature calcination at 700°C. The combustion process was carried out using compressed air at a rate of 25 L / min for 180 minutes. After calcination, steam was introduced for cooling at a flow rate of 3 L / min, yielding calcium-based carbon dioxide adsorbent powder. This powder was then uniformly mixed with 2% (w / w) polyvinylpyrrolidone and 50% (w / w) deionized water, extruded, and cut into columnar particles with a diameter of 5-6 mm and a height of 5-6 mm. The columnar particles were then dried in a forced-air drying oven at 85°C for 24 hours, and then transferred to a high-temperature atmosphere furnace for high-temperature calcination under high-flow-rate nitrogen purging conditions. The furnace temperature range was 700°C, the nitrogen flow rate was 15 L / min, and the calcination time was 180 min. After calcination, calcium-based carbon dioxide adsorbent particles were obtained.

[0102] Example 2

[0103] Take 296g of quicklime powder, 840g of citric acid monohydrate powder, 13.2g of magnesium oxide powder, and 26.4g of alumina powder, and mix them evenly. The resulting powder mixture will be used in the next step. Add 2.2L of deionized water to a stirred reactor and raise the temperature to 80℃. Slowly add the powder mixture obtained in the previous step to the stirred reactor and react at a stirring rate of 300r / min for 2 hours to generate a viscous suspension. Transfer the viscous suspension to a flat container and dry it in a forced-air drying oven at 110℃ for 18 hours to obtain dried solid blocks. The dried material was crushed into solid powder using a pulverizer and sieved to below 300 mesh. The powder was then transferred to a medium-temperature atmosphere furnace for combustion at 500°C. The furnace was purged with compressed air at a rate of 5 L / min for 60 minutes. After combustion, the calcium-based carbon dioxide adsorbent precursor was transferred to a high-temperature atmosphere furnace for high-temperature calcination at 800°C. The furnace was purged with compressed air at a rate of 20 L / min for 120 minutes. After calcination, steam was introduced for cooling at a flow rate of 5 L / min, yielding calcium-based carbon dioxide adsorbent powder. This powder was then uniformly mixed with 3% (w / w) polyvinylpyrrolidone and 55% (w / w) deionized water, extruded, and cut into columnar particles with a diameter of 5-6 mm and a height of 5-6 mm. The columnar particles were then dried in a forced-air drying oven at 105°C for 8 hours, and then transferred to a high-temperature atmosphere furnace for high-temperature calcination under high-flow-rate nitrogen purging conditions. The furnace temperature range was 900°C, the nitrogen flow rate was 20 L / min, and the calcination time was 60 min. After calcination, calcium-based carbon dioxide adsorbent particles were obtained.

[0104] Example 3

[0105] Take 296g of quicklime powder, 840g of citric acid monohydrate powder, 26.4g of magnesium oxide powder, and 13.2g of alumina powder, and mix them evenly. The resulting powder mixture will be used in the next step. Add 2.2L of deionized water to a stirred reactor and raise the temperature to 80℃. Slowly add the powder mixture obtained in the previous step to the stirred reactor and react at a stirring rate of 300r / min for 2 hours to generate a viscous suspension. Transfer the viscous suspension to a flat container and dry it in a forced-air drying oven at 110℃ for 18 hours to obtain dried solid blocks. The dried material was crushed into solid powder using a pulverizer and sieved to below 300 mesh. The powder was then transferred to a medium-temperature atmosphere furnace for combustion at 550°C. The furnace was purged with compressed air at a rate of 1 L / min for 90 minutes. After combustion, the calcium-based carbon dioxide adsorbent precursor was transferred to a high-temperature atmosphere furnace for calcination at 900°C. The furnace was purged with compressed air at a rate of 15 L / min for 90 minutes. After calcination, steam was introduced for cooling at a flow rate of 8 L / min, yielding calcium-based carbon dioxide adsorbent powder. This powder was then uniformly mixed with 4% (w / w) polyvinylpyrrolidone and 60% (w / w) deionized water, extruded, and cut into columnar particles with a diameter of 5-6 mm and a height of 5-6 mm. The columnar particles were then dried in a forced-air drying oven at 95°C for 18 hours, and then transferred to a high-temperature atmosphere furnace for high-temperature calcination under high-flow-rate nitrogen purging conditions. The furnace temperature range was 800°C, the nitrogen flow rate was 25 L / min, and the calcination time was 90 min. After calcination, calcium-based carbon dioxide adsorbent particles were obtained.

[0106] Example 4

[0107] Take 296g of quicklime powder, 840g of citric acid monohydrate powder, 26.4g of magnesium oxide powder, and 26.4g of aluminum oxide powder, and mix them evenly. The resulting powder mixture will be used in the next step. Add 2.2L of deionized water to a stirred reactor and raise the temperature to 80℃. Slowly add the powder mixture obtained in the previous step to the stirred reactor and react at a stirring rate of 300r / min for 2 hours to generate a viscous suspension. Transfer the viscous suspension to a flat container and dry it in a forced-air drying oven at 110℃ for 18 hours to obtain dried solid blocks. The dried material was crushed into solid powder using a pulverizer and sieved to below 300 mesh. The powder was then transferred to a medium-temperature atmosphere furnace for combustion at 600°C. The furnace was purged with compressed air at a rate of 4 L / min for 30 minutes. After combustion, the calcium-based carbon dioxide adsorbent precursor was transferred to a high-temperature atmosphere furnace for high-temperature calcination at 950°C. The furnace was purged with compressed air at a rate of 10 L / min for 60 minutes. After calcination, steam was introduced for cooling at a flow rate of 10 L / min to obtain calcium-based carbon dioxide adsorbent powder. This powder was then uniformly mixed with 5% polyvinylpyrrolidone and 45% deionized water, extruded, and cut into columnar particles with a diameter of 5-6 mm and a height of 5-6 mm. The columnar particles were then dried in a forced-air drying oven at 80°C for 18 hours, and then transferred to a high-temperature atmosphere furnace for high-temperature calcination under high-flow-rate nitrogen purging conditions. The furnace temperature range was 850°C, the nitrogen flow rate was 30 L / min, and the calcination time was 120 min. After calcination, calcium-based carbon dioxide adsorbent particles were obtained.

[0108] Comparative Example

[0109] Commercially available calcium oxide was used as raw material to granulate calcium-based carbon dioxide adsorbent particles of the same size as those in the example.

[0110] The above embodiments and comparative examples underwent infrared spectroscopy analysis, carbon dioxide capture performance testing, carbon dioxide adsorption capacity, carbon dioxide capture performance, particle compressive strength, and particle wear resistance testing on a simultaneous thermal analyzer. The test results are shown in Table 1 and... Figure 2-13 As shown.

[0111] The method for testing carbon dioxide adsorption capacity is as follows: Calcium-based carbon dioxide adsorbent particles are ground into powder and sieved to a size of 300-400 mesh. For each test, approximately 5-6 mg of powder is loaded into a 40 μL alumina crucible, and the test is conducted according to the following procedure: First, the sample is pre-calcined in a nitrogen atmosphere at a rate of 100 mL / min: the temperature is increased from 20℃ to 850℃ at a rate of 30℃ / min and held constant for 20 min to ensure complete decomposition of residual calcium hydroxide and calcium carbonate in the sample. Then, the temperature is decreased from 850℃ to 650℃ at a rate of 30℃ / min. At 650℃, the atmosphere is adjusted to 15 mL / min carbon dioxide + 85 mL / min nitrogen for carbonation testing for 60 min. After the carbonation stage, the atmosphere was adjusted to a nitrogen atmosphere of 100 mL / min, and the temperature was increased from 650℃ to 850℃ at a rate of 30℃ / min to enter the calcination stage, with a holding time of 10 min, to complete the decomposition of calcium carbonate and the regeneration of calcium oxide in the calcium-based carbon dioxide adsorbent. Each cycle consisted of one carbonation stage and one calcination stage. The test was repeated for 25 cycles for each sample, and the carbon dioxide adsorption capacity of the sample in each cycle was calculated.

[0112] Carbon dioxide capture performance test: 200g of calcium-based carbon dioxide adsorbent particles were loaded into a vertical fixed-bed reactor, and simulated tail gas was introduced for performance evaluation. The test operating conditions of the fixed-bed reactor were: simulated tail gas flow rate 1L / min, composition 15% carbon dioxide, 30% water vapor, and the remainder nitrogen, adsorption temperature 650℃, and reaction time 100min. The conversion rate, adsorption capacity, and tail gas carbon dioxide removal rate of the calcium-based carbon dioxide adsorbent particles were determined. As a comparison, 200g of comparative particles with a particle size range of 5-6mm were also loaded into a fixed-bed reactor, and simulated tail gas was introduced for performance evaluation. The test operating conditions of the fixed-bed reactor were: simulated tail gas flow rate 1L / min, composition 15% carbon dioxide, 30% water vapor, and the remainder nitrogen, adsorption temperature 650℃, and reaction time 100min.

[0113] Particle compressive strength test: For each test, a particle is placed sideways on the instrument platform of the particle strength tester. The instrument probe gradually increases the force applied to the particle from zero until the particle breaks. The sensor records the force value when the particle breaks. 20 particles are measured in each group, and the average value is calculated and recorded as the compressive strength of the particle sample.

[0114] Particle wear resistance test: Take 20g of calcium-based carbon dioxide adsorbent particles into the sample tray of the brittleness analyzer. The sample tray rotates at 25rpm to generate friction between the particles. The rotation time is 60min. After the rotation, the sample is sieved, and the mass of particles with a particle size still in the range of 5-6mm is weighed and the ratio of the particle size to the initial mass of the particles is calculated and recorded as the wear test particle size retention rate.

[0115] Table 1 Test Results

[0116]

[0117] The infrared spectra of Examples 1-4 are as follows: Figure 2-5 As shown, the characteristic peak corresponding to calcium oxide in the infrared spectra of Examples 1-4 has the highest intensity, indicating that calcium oxide is the most important phase in these examples. This component is the main component responsible for the carbon dioxide capture function of the calcium-based carbon dioxide adsorbent particles. Meanwhile, a characteristic peak of calcium hydroxide with a lower intensity can also be identified in the infrared spectra. This is because calcium oxide readily reacts with water vapor in the air during the sample preparation stage before infrared testing. Furthermore, the presence of MgAl2O4 (spinel) can also be identified in the infrared spectra, indicating that magnesium oxide reacts with aluminum oxide to form MgAl2O4 during the preparation process of this example. This spinel structure is an inert metal oxide with a high melting point, which can enhance the anti-sintering ability of the calcium-based carbon dioxide adsorbent particles and improve the stability of the circulating carbon dioxide capture performance. In addition, the presence of Ca3Al2O6 (calcium aluminum oxide) can also be identified in the infrared spectra of Example 2, and some unreacted magnesium oxide can be identified in the infrared spectra of Examples 3 and 4. Calcium aluminum oxide and magnesium oxide can also enhance the anti-sintering ability of the calcium-based carbon dioxide adsorbent particles and improve the stability of the circulating carbon dioxide capture performance.

[0118] The carbon dioxide capture performance test was conducted on a synchronous thermal analyzer. Examples 1-4 show the change in carbon dioxide adsorption capacity over time during the first cycle as follows: Figure 6-9 As shown, by Figure 6-9It can be seen that the examples have the highest carbonation reaction rate in the initial stage of the carbonation reaction, that is, in the reaction control stage. By taking the first derivative of the curve, the highest reaction rates of Examples 1-4 in this stage are 0.143 g carbon dioxide / g adsorbent / min, 0.0706 g carbon dioxide / g adsorbent / min, 0.1025 g carbon dioxide / g adsorbent / min, and 0.0878 g carbon dioxide / g adsorbent / min, respectively. Subsequently, with the formation of a calcium carbonate product layer on the outer surface of the calcium-based carbon dioxide adsorbent, the reaction enters the product layer diffusion stage. At this time, the carbonation reaction rate changes significantly, and gradually decreases as the carbonation reaction proceeds. After a 60-minute carbonation reaction stage, the carbon dioxide adsorption capacities achievable in Examples 1-4 are 0.695 g carbon dioxide / g adsorbent, 0.591 g carbon dioxide / g adsorbent, 0.644 g carbon dioxide / g adsorbent, and 0.544 g carbon dioxide / g adsorbent, respectively. Therefore, the average carbonation reaction rates in Examples 1-4 during the 60-minute carbonation reaction stage are 0.0116 g carbon dioxide / g adsorbent / min, 0.0099 g carbon dioxide / g adsorbent / min, 0.076 g carbon dioxide / g adsorbent / min, and 0.0091 g carbon dioxide / g adsorbent / min, respectively. For comparison, the variation curves of the comparative examples are also... Figure 6-9 The results are shown in the figure. It can be seen that the reaction rate of the comparative example is significantly lower than that of Examples 1-4. By taking the first derivative of the curve, the highest reaction rate of the comparative example in this stage is 0.076 g carbon dioxide / g adsorbent / min. After a 60-min carbonation reaction stage, the carbon dioxide adsorption capacity reached by the comparative example is 0.477 g carbon dioxide / g adsorbent. Therefore, the average carbonation reaction rate during the 60-min carbonation reaction stage is 0.0080 g carbon dioxide / g adsorbent / min. As can be seen, the highest carbonation reaction rate of Example 1 in the first cycle was 1.88 times that of the comparative example, and the average carbonation reaction rate during the 60-minute carbonation reaction stage was 1.45 times that of the comparative example. The maximum carbonation reaction rate of Example 2 in the first cycle did not have a significant advantage over the comparative example, because some calcium oxide reacted with the added alumina to generate the inert component Ca3Al2O6, but the average carbonation reaction rate during the 60-minute carbonation reaction stage was 1.24 times that of analytically pure calcium oxide. The highest carbonation reaction rate of Example 3 in the first cycle was 1.35 times that of the comparative example, and the average carbonation reaction rate during the 60-minute carbonation reaction stage was 1.34 times that of the comparative example. The highest carbonation reaction rate of Example 4 in the first cycle was 1.16 times that of the comparative example, and the average carbonation reaction rate during the 60-minute carbonation reaction stage was 1.14 times that of the comparative example.

[0119] The carbon dioxide adsorption capacity of Examples 1-4 as a function of cycle number is shown in the curves. Figure 10-13 As shown. First, the carbon dioxide capture performance degradation rates of Examples 1-4 after 25 cycles were 20.7%, no significant degradation, 15.4%, and 5.15%, respectively. For comparison, the carbon dioxide adsorption capacity of the comparative examples under the same test conditions also changed with the number of cycles. Figure 4 As shown in the figure, the carbon dioxide capture performance of the comparative example decreased by 75.9% after 25 cycles. This is because the comparative example underwent severe sintering under high-temperature conditions during multiple carbonation / calcination cycles. The comparison showed that Example 1 exhibited a 45.7% increase in carbon dioxide adsorption capacity in the first cycle and a 379.1% increase in the 25th cycle compared to the comparative example, with a 72.7% improvement in performance stability over 25 cycles. This indicates that Example 1's carbon dioxide adsorption capacity in the first cycle was 1.46 times that of the comparative example, its carbon dioxide adsorption capacity in the 25th cycle was 4.79 times that of the comparative example, and its performance stability over 25 cycles was 3.51 times that of the comparative example. Example 2 showed a 23.9% increase in carbon dioxide adsorption capacity in the first cycle and a 425.2% increase in the 25th cycle, with a significant improvement in performance stability over 25 cycles. This indicates that Example 2's carbon dioxide adsorption capacity in the first cycle was 1.24 times that of analytical grade calcium oxide, its carbon dioxide adsorption capacity in the 25th cycle was 5.25 times that of analytical grade calcium oxide, and no significant performance degradation was observed over 25 cycles. Compared to the comparative example, Example 3 showed a 35% increase in carbon dioxide adsorption capacity in the first cycle, a 373.9% increase in the 25th cycle, and a 79.7% improvement in performance stability over 25 cycles. Therefore, Example 3's carbon dioxide adsorption capacity in the first cycle was 1.35 times that of the comparative example, its carbon dioxide adsorption capacity in the 25th cycle was 4.74 times that of the comparative example, and its performance stability over 25 cycles was 4.93 times that of the comparative example. Similarly, Example 4 showed a 14% increase in carbon dioxide adsorption capacity in the first cycle, a 348.7% increase in the 25th cycle, and a 93.2% improvement in performance stability over 25 cycles. Therefore, Example 4's carbon dioxide adsorption capacity in the first cycle was 1.14 times that of the comparative example, its carbon dioxide adsorption capacity in the 25th cycle was 4.49 times that of the comparative example, and its performance stability over 25 cycles was 14.7 times that of the comparative example.

[0120] As shown in Table 1, the conversion rate, adsorption capacity and carbon dioxide removal rate of Examples 1-4 are significantly higher than those of the comparative particles, which are 2.0-2.9 times higher. Furthermore, Examples 1-4 have higher compressive strength and wear resistance, which are 2.51-4.29 times higher than those of the comparative particles.

[0121] The above are merely preferred embodiments of this application and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the description of this application, or direct or indirect applications in other related technical fields, are similarly included within the patent scope of this application.

Claims

1. A method for preparing a calcium-based carbon dioxide adsorbent, characterized in that, The preparation method of the calcium-based carbon dioxide adsorbent includes the following steps: Calcium hydroxide, an unsaturated organic compound, magnesium oxide, and aluminum oxide are obtained. The calcium hydroxide, unsaturated organic compound, magnesium oxide, and aluminum oxide are mixed and added to a solvent. The mixture is heated and stirred to obtain a mixed suspension. The unsaturated organic compound is citric acid. The total mass of magnesium oxide and aluminum oxide in the calcium-based carbon dioxide adsorbent is less than 19% of the total mass. The mass ratio of the unsaturated organic compound to calcium hydroxide is (0.6~1.2):

1. During the heating and stirring process, at least a portion of the calcium hydroxide reacts with at least a portion of the unsaturated organic compound to form calcium organic acid; The mixed suspension was dried to obtain dried powder. The dried powder is subjected to medium-temperature combustion to obtain a calcium-based carbon dioxide adsorbent precursor, wherein the medium-temperature combustion temperature is 400~600℃. The calcium-based carbon dioxide adsorbent precursor is subjected to a first high-temperature calcination to obtain calcium-based carbon dioxide adsorbent powder, wherein the temperature of the first high-temperature calcination is 700~1000℃. The calcium-based carbon dioxide adsorbent powder is mixed with a binder and a solvent, and the mixture is granulated to form granular mixture particles; the granular mixture particles are then subjected to a second high-temperature calcination to obtain granular calcium-based carbon dioxide adsorbent. The calcium-based carbon dioxide adsorbent includes calcium oxide, and also includes at least one of calcium aluminum oxide, aluminum magnesium oxide, and calcium magnesium oxide, wherein the calcium oxide accounts for more than or equal to 80% by mass in the calcium-based carbon dioxide adsorbent.

2. The method for preparing the calcium-based carbon dioxide adsorbent as described in claim 1, characterized in that, The adhesive comprises at least one of polyvinylpyrrolidone and hydroxypropyl methylcellulose; And / or, the amount of the adhesive added is 2-5% of the mass of the calcium-based carbon dioxide adsorbent powder; And / or, in the step of mixing the calcium-based carbon dioxide adsorbent powder with a binder and a solvent, and granulating the mixture, the amount of solvent added is 40 to 60% of the mass of the calcium-based carbon dioxide adsorbent powder.

3. The method for preparing the calcium-based carbon dioxide adsorbent as described in claim 1, characterized in that, The step of subjecting the mixture particles to a second high-temperature calcination to obtain granular calcium-based carbon dioxide adsorbent includes: The mixture particles are dried at 80~110℃ for 8~24h. After drying, they are subjected to a second high-temperature calcination at 700~1000℃ under nitrogen purging to obtain granular calcium-based carbon dioxide adsorbent. The second high-temperature calcination time is 60~180min, and the nitrogen flow rate for nitrogen purging is 10~30L / min.

4. The method for preparing the calcium-based carbon dioxide adsorbent as described in claim 1, characterized in that, The intermediate-temperature combustion is carried out under the first air purging, wherein the air flow rate of the first air purging is 1~5L / min; And / or, the combustion time of the medium-temperature combustion is 30~150 min.

5. The method for preparing the calcium-based carbon dioxide adsorbent as described in claim 1, characterized in that, The first high-temperature calcination is carried out under the second air purging, wherein the air flow rate of the second air purging is 10~30L / min; And / or, the calcination time of the first high-temperature calcination is 60~180 min.

6. A calcium-based carbon dioxide adsorbent, characterized in that, The calcium-based carbon dioxide adsorbent is prepared using the method described in any one of claims 1 to 5.

7. The calcium-based carbon dioxide adsorbent prepared by the method of any one of claims 1 to 5, or the calcium-based carbon dioxide adsorbent of claim 6, is used in the capture of carbon dioxide in the exhaust gas of methanol-fueled vehicles.

Images