Calcium-based co2 adsorbent and preparation method and application thereof

Abstract

The application discloses a calcium-based CO2 adsorbent and a preparation method and application thereof, and the preparation method comprises the following steps: (1) a silicon-containing compound is mixed with a solvent A, and then the pH value of the system is regulated to obtain a material flow A; (2) the material flow A, an additive A and a carbon source are mixed, and after heat treatment, a material flow B is obtained; (3) the material flow B, a calcium source and a solvent B are uniformly mixed, then an additive B is introduced, and after drying, a material flow C is obtained, and the calcium-based CO2 adsorbent is obtained by further processing under the condition that microwaves exist. Meanwhile, the application also provides the calcium-based CO2 adsorbent obtained by using the above preparation method. The provided adsorbent preparation method is simple and easy to implement, the obtained adsorbent has the advantages of wear resistance, high adsorption capacity, sintering resistance, microwave heating and the like, and long-period cyclic use can be realized.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of adsorption separation technology, and particularly relates to an adsorbent material for adsorption and separation of carbon dioxide and a preparation method thereof. BACKGROUND

[0002] High-temperature solid CO2 adsorbents can directly capture CO2 in flue gas or tail gas of coal-fired power plants or other industrial processes without the need for prior cooling of high-temperature gas, which is simple and easy to operate. Calcium-based CO2 adsorbents have become a high-temperature solid CO2 adsorbent with the most industrialization prospects because of their fast adsorption rate and high theoretical capacity. At the same time, calcium-based CO2 adsorbents can also be applied to other processes to capture CO2 in situ or to complete the transfer of CO2 in the process by using the adsorption and desorption processes of CO2. For example, in chemical processes such as biomass gasification, ethanol reforming to produce hydrogen, and methane to produce hydrogen, the application of calcium-based CO2 adsorbents can affect the reaction equilibrium, change the reaction path, and improve the product quality. In the above treatment processes, calcium-based CO2 adsorbents often need to move in different reactors or even be mixed directly with the material, and higher requirements are also put forward for their wear resistance and stability.

[0003] Due to the low Tamman temperature of CaCO3, the large difference in molar volume between CaCO3 and CaO, and other reasons, the effective components of calcium-based CO2 adsorbents are easy to sinter and fuse, and the pore channels are easy to collapse during the adsorption / desorption cycle process of CO2 in the carbonation / calcination regeneration, resulting in rapid decay of the carbonation conversion rate of the adsorbent, rapid reduction of the adsorption capacity, and significant decrease of the specific surface area. In view of the above problems, researchers provide skeleton support to alleviate the sintering of the adsorbent and maintain its structural properties through methods such as doping high-Tamman-temperature inert components containing Zr and morphology control. However, after the above modification, the mechanical strength of the calcium-based adsorbent is limited, and in process scenarios where the adsorbent needs to move, especially in moving bed, fluidized bed and other processes, its strength is far from meeting the requirements. At the same time, traditional high-Tamman-temperature inert components are relatively stable when adsorbing CO2 in flue gas of coal-fired power plants, but they may react in some process scenarios where they are mixed with materials, thereby affecting the stability of the calcium-based adsorbent.

[0004] CN102671618A discloses a preparation method of microspherical nano-CaO-based CO2 adsorbent for circulating fluidized bed, which mixes nano-CaCO3 suspension, additives and aluminum sol uniformly, then sprays and granulates to obtain microspherical particles, and then calcines to obtain the adsorbent. However, the adsorbent prepared by the above patent still has relatively large wear, and it still has difficulties in process scenarios where it is mixed with materials. SUMMARY

[0005] In view of the problems existing in the use of the existing CO2 adsorbents, the core purpose of the present application is to provide a calcium-based CO2 adsorbent and a preparation method and application thereof, the preparation method is simple and easy to implement, the obtained adsorbent has the advantages of wear resistance, high adsorption capacity, sintering resistance, microwave heating, etc., and can realize long-period cyclic use.

[0006] The technical scheme of the present application mainly includes the following aspects:

[0007] The first aspect of the present application provides a preparation method of a calcium-based CO2 adsorbent, comprising the following steps:

[0008] (1) mixing a silicon-containing compound with a solvent A, then adjusting the pH value of the system to obtain a stream A;

[0009] (2) mixing the stream A, an additive A and a carbon source, and then performing heat treatment to obtain a stream B;

[0010] (3) uniformly mixing the stream B, a calcium source and a solvent B, then introducing an additive B, and then performing drying to obtain a stream C, and further treating the stream C in the presence of microwaves to obtain the calcium-based CO2 adsorbent.

[0011] Preferably, in the preparation method of the calcium-based CO2 adsorbent, the silicon-containing compound in step (1) is selected from one or more of soluble silicate, alkoxysilane and silicon tetrachloride; further specifically, the soluble silicate can be one or more of sodium silicate, lithium silicate, potassium silicate and ammonium silicate, and the alkoxysilane can be one or more of methyl orthosilicate, ethyl orthosilicate, propyl orthosilicate, isopropyl orthosilicate, dimethyldiethoxysilane, methyltriethoxysilane, methyltrimethoxysilane, vinyltriethoxysilane and n-octyltriethoxysilane; preferably, one or more of sodium silicate, ethyl orthosilicate and dimethyldiethoxysilane.

[0012] Preferably, in the preparation method of the calcium-based CO2 adsorbent, the solvent A in step (1) is water or a mixture of water and an organic solvent, and the organic solvent is alcohol selected from one or more of ethanol, methanol, propanol, butanol, ethylene glycol, propylene glycol, glycerol and butanediol; further preferably, the alcohol is ethanol. When the solvent A is a mixture of water and alcohol, the concentration of the alcohol is 1wt%-80wt%.

[0013] Preferably, in the preparation method of the calcium-based CO2 adsorbent, the solvent A in step (1) further comprises component A, wherein the component A can be one or more of silicone oil, hexamethylenetetramine, formamide, N,N-dimethylformamide and polyethylene glycol (molecular weight: 200-20000); and the content of the component A is 1wt%-50wt% based on the weight of the silicon-containing compound.

[0014] Preferably, in the preparation method of the calcium-based CO2 adsorbent, the pH value of the system in step (1) is controlled to 1-12, preferably 1-10; the pH value of the system can be controlled by introducing acid or ammonia water, and the acid can be one or more of nitric acid, hydrochloric acid, phosphoric acid, oxalic acid, and citric acid.

[0015] Preferably, in the preparation method of the calcium-based CO2 adsorbent, the auxiliary A in step (2) is one or more of metal nitrate, metal carbonate, metal phosphate, metal organic acid salt, and metal chloride, wherein the corresponding metal cation in the salt can be one or more of aluminum, iron, magnesium, copper, silver, nickel, zirconium, cerium, lanthanum, yttrium, manganese, titanium, ytterbium, and neodymium; preferably, the auxiliary A is one or more of aluminum nitrate, iron nitrate, magnesium nitrate, copper nitrate, silver nitrate, nickel nitrate, zirconium nitrate, cerium nitrate, lanthanum nitrate, yttrium nitrate, manganese nitrate, titanium tetrachloride, ytterbium nitrate, neodymium nitrate, basic aluminum acetate, magnesium acetate, magnesium oxalate, and zirconium acetate; more preferably, the auxiliary A is one or more of aluminum nitrate, iron nitrate, magnesium nitrate, copper nitrate, silver nitrate, and nickel nitrate.

[0016] Preferably, in the preparation method of the calcium-based CO2 adsorbent, the carbon source in step (2) can be one or more of activated carbon, carbon black, and semi-coke, preferably activated carbon, and further preferably the specific surface area of the activated carbon is greater than 200 m 2 / g; the activated carbon can be one or more of biomass-based activated carbon, coal-based activated carbon, and petroleum-based activated carbon, preferably biomass-based activated carbon. The carbon source can be a commercially available product or prepared according to the method disclosed in the prior art.

[0017] Preferably, in the preparation method of the calcium-based CO2 adsorbent, the carbon source in step (2) can be prepared by the following method: uniformly mixing biomass and an activating agent, and then performing heat treatment and washing to obtain the carbon source.

[0018] Further, the biomass can be one or more of sawdust, coconut shell, straw, bamboo chips, rice husk, tung oil shell, pomelo peel, starch, lignin, and cellulose.

[0019] Further, the activating agent can be one or more of potassium hydroxide, sodium hydroxide, potassium carbonate, zinc chloride, phosphoric acid, and sulfuric acid.

[0020] Further, the heat treatment temperature is 350-900°C, the heat treatment time is 0.5-10 hours, and the heat treatment is performed in the presence of nitrogen or an inert gas, which can be one or more of helium, neon, argon, krypton, and xenon.

[0021] Further, the washing is washing with an acid solution or an alkali solution and then washing with deionized water until no activated agent ions are detected, the acid can be one or more of hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, oxalic acid, citric acid, and the alkali can be one or more of sodium hydroxide, potassium hydroxide, lithium hydroxide.

[0022] Further, the mass ratio of the activated agent to the biomass is 0.2:1-5:1.

[0023] Preferably, in the preparation method of the calcium-based CO2 adsorbent, the dry basis content of the auxiliary A is 0.01wt%-10.0wt% based on the mass of the silicon-containing compound, and the mass ratio of the carbon source to the silicon-containing compound is 0.1:1-10:1.

[0024] Preferably, in the preparation method of the calcium-based CO2 adsorbent, the heat treatment in step (2) includes two steps of drying and calcination, the drying temperature is 100-150°C, the calcination temperature is 350-900°C, the calcination time is 0.2-10 hours, and the calcination is carried out in the presence of a reducing atmosphere; the reducing atmosphere is any one of a reducing gas, a mixed gas of a reducing gas and an inert atmosphere; the reducing gas is one or more of hydrogen, carbon monoxide, methane, C2-C4 gas, preferably hydrogen and / or methane; and the volume content of the reducing gas in the mixed gas is 0.5%-99.5%. The inert atmosphere is nitrogen and / or an inert gas, and the inert gas is one or more of helium, neon, argon, krypton, and xenon.

[0025] Preferably, in the preparation method of the calcium-based CO2 adsorbent, the carbon source in step (2) can be crushed and sieved as needed before mixing, and the carbon source with a particle size of 10-80 mesh is preferred.

[0026] Preferably, in the preparation method of the calcium-based CO2 adsorbent, the separation treatment is preferably carried out before the heat treatment in step (2), and the solid-phase material obtained by the separation is subjected to the heat treatment.

[0027] Preferably, in the preparation method of the calcium-based CO2 adsorbent, the calcium source in step (3) can be one or more of calcium oxide, calcium hydroxide, and calcium salt, preferably the calcium source is one or more of calcium oxide, calcium oxalate, calcium gluconate, calcium hydroxide, calcium carbonate, calcium acetate, calcium propionate, calcium acetylacetonate, calcium lactate, calcium formate, calcium citrate, and calcium nitrate, and further preferably the calcium source is one or more of calcium oxide, calcium oxalate, and calcium nitrate.

[0028] Preferably, in the preparation method of the calcium-based CO2 adsorbent, the solvent B in step (3) is water and / or an organic solvent; the organic solvent is preferably an alcohol solvent, and the alcohol solvent is a small molecule (1-4 carbon atoms) alcohol solvent, which can be selected from one or more of ethanol, methanol, propanol, butanol, ethylene glycol, propylene glycol, glycerol, and butanediol, and is further preferably ethanol; when the solvent B is a mixed solvent of water and an organic solvent, the concentration of the organic solvent is 1wt%-80wt%.

[0029] Preferably, in the preparation method of the calcium-based CO2 adsorbent, the additive B in step (3) can be selected from one or more of carboxymethyl cellulose, hydroxyethyl cellulose, microcrystalline cellulose, chitosan, sesbania gum, hydroxypropyl methyl cellulose, polyvinyl alcohol (molecular weight 0.5-150,000), silica sol, aluminum dihydrogen phosphate, and solutions thereof, and is preferably one or more of carboxymethyl cellulose, sesbania gum, polyvinyl alcohol (molecular weight 0.5-150,000), silica sol, and solutions thereof.

[0030] Preferably, in the preparation method of the calcium-based CO2 adsorbent, in step (3), the mass ratio of the solvent B to the calcium source is 0.2:1-20:1, the mass ratio of the calcium source to the flow B is 0.01:1-2:1, and the dry basis content of the additive B is 0.5wt%-10wt%.

[0031] Preferably, in the preparation method of the calcium-based CO2 adsorbent, in step (3), a molding process is preferably performed before drying. The molding technology is a prior art known to those skilled in the art, and the specific molding operation can be selected by those skilled in the art according to actual needs, which can be any shape such as a cylindrical bar, a three-leaf clover shape, a four-leaf clover shape, a spherical shape, and the like, and is preferably a spherical shape. The balling molding method can be one or more of extrusion balling molding, rolling molding, and spray drying molding.

[0032] Preferably, in the preparation method of the calcium-based CO2 adsorbent, the drying temperature in step (3) is 100-150°C.

[0033] Preferably, in the preparation method of the calcium-based CO2 adsorbent, after drying in step (3), a calcination process can be further performed, the calcination temperature is 350-900°C, the calcination time is 1-10 hours, the calcination is performed in the presence of an inert atmosphere, the inert atmosphere is nitrogen and / or an inert gas, and the inert gas is one or more of helium, neon, argon, krypton, and xenon.

[0034] Preferably, in the preparation method of the calcium-based CO2 adsorbent, the microwave power in step (3) is 10-1000 W / (g of material), preferably 100-500 W / (g of material); the microwave treatment time is 0.1-10 hours, preferably 0.1-1 hour; the microwave treatment is further preferably carried out in the presence of an inert gas, which is one or more of helium, neon, argon, krypton and xenon.

[0035] Preferably, in the preparation method of the calcium-based CO2 adsorbent, the preparation method of the calcium-based CO2 adsorbent further comprises step (4), which is heat treatment of the material obtained in step (3) in an oxygen-containing atmosphere, the heat treatment temperature is 500-1300℃, preferably 500-800℃, and the heat treatment time is 0.5-8 hours. The oxygen-containing atmosphere can be any one of air, oxygen, and a mixed gas of oxygen and an inert atmosphere, wherein the oxygen content in the mixed gas is 5-99.99%; the inert atmosphere is nitrogen and / or an inert gas, which is one or more of helium, neon, argon, krypton and xenon.

[0036] The second aspect of the present application provides a calcium-based CO2 adsorbent obtained by the above preparation method.

[0037] The third aspect of the present application provides the use of the calcium-based CO2 adsorbent obtained by the above preparation method in adsorbing CO2.

[0038] The calcium-based CO2 adsorbent and the preparation method thereof provided by the present application have the following technical effects and advantages:

[0039] 1. In the preparation method of the calcium-based CO2 adsorbent, the carbon source plays a role of a template and a pore-forming agent to a certain extent, which guides the control of the surface morphology of the adsorbent, promotes the generation of pore structures, buffers the local volume change in the adsorption / desorption cycle process, ensures the structural stability, and is beneficial to the diffusion and adsorption of CO2.

[0040] 2. In the preparation method of the calcium-based CO2 adsorbent, the additive A can form metal particles on the surface of the precursor particles, which have a strong interaction with microwaves, produce Joule heating effect, and even can cause microwave discharge phenomenon, causing local intense heating and strengthening the microwave selective heating effect; in addition, the metal particles can also generate high Tamman temperature inert components to alleviate the sintering of CaO particles. The introduction of metal active components (such as nickel, iron and cobalt) can also reduce the difficulty of silicon carbide synthesis.

[0041] 3. In the preparation method of the calcium-based CO2 adsorbent provided by the application, the material is heated under microwave conditions, and the different components are heated selectively by taking advantage of the great difference in dielectric characteristics, so that hot spots are formed by carbon, metal particles and newly generated silicon carbide, thereby strengthening the hot spot effect and selective heating effect of the microwaves, promoting the rapid generation of silicon carbide and the formation of a support skeleton, and preventing the sintering of CaO active particles, thereby solving the problem of in-situ generation of silicon carbide.

[0042] 4. In the preparation method of the calcium-based CO2 adsorbent provided by the application, silicon carbide with excellent mechanical strength and thermal stability is introduced by in-situ reaction, and is used as a support skeleton, which can effectively alleviate and prevent the sintering of CaO, improve the wear resistance, ensure the adsorption capacity and cycle stability, and ensure the chemical stability of the adsorbent in the process of direct mixing with materials, thereby facilitating the long-term cyclic use of the adsorbent. DETAILED DESCRIPTION

[0043] The specific content and effects of the method of the application will be further described below through specific examples, but the scope of the application is not limited by this. In the application, the molecular weight of the polyvinyl alcohol is the viscosity average molecular weight.

[0044] The specific embodiments of the application will be described in detail below, but it should be pointed out that the protection scope of the application is not limited by these specific embodiments, but is determined by the claims in the appendix.

[0045] All publications, patent applications, patents and other references mentioned in this specification are hereby incorporated by reference. Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as commonly understood by one of ordinary skill in the art. In case of conflict, the definition in this specification prevails.

[0046] When the specification derives materials, substances, methods, steps, devices or components, etc. with the word head "known to those skilled in the art", "prior art" or similar terms, the objects derived by the word head cover those commonly used in the art at the time of the application, but also include those not commonly used at present, but will be recognized as suitable for similar purposes in the art.

[0047] Unless otherwise explicitly stated, throughout the specification and claims, the term "comprise" or its variants such as "contain" or "include" will be understood to include the stated elements or components, but not exclude other elements or components. In this text, all numerical values of parameters (for example, quantities or conditions) should be understood as being modified by the term "about" in all cases, whether the term "about" actually appears before the numerical value or not.

[0048] All percentages, parts, ratios, etc., mentioned in the present description are by weight, unless otherwise indicated, and pressures are at or near atmospheric pressure, unless otherwise indicated.

[0049] In the context of the present description, any two or more embodiments of the present application can be combined, and the resulting technical solutions thus formed are part of the original disclosure of the present description and also fall within the scope of protection of the present application.

[0050] The following examples and comparative examples were prepared under conventional conditions or under conditions recommended by the manufacturer, unless otherwise specified. The reagents or instruments used, when not specified by the manufacturer, are conventional products that can be obtained by commercial means.

[0051] Example 1

[0052] The bamboo charcoal powder was mixed with potassium hydroxide uniformly, and then was kept at a constant temperature of 800°C for 4 hours under a nitrogen atmosphere, the mass ratio of potassium hydroxide to bamboo charcoal powder being 0.8:1. After washing with hydrochloric acid solution and then with deionized water, a carbon source was obtained. N,N-dimethylformamide was added to deionized water containing 1% methanol, and was stirred rapidly. Sodium silicate was added slowly, and the pH was adjusted to 1-2 with hydrochloric acid to obtain a stream A. The carbon source and nickel nitrate were slowly added to the stream A, the content of N,N-dimethylformamide being 50% and the content of nickel nitrate being 0.2% based on the mass of sodium silicate, and the mass ratio of carbon source to sodium silicate being 2:1. Drying was performed at 150°C, and then the material was kept at a constant temperature of 900°C for 0.2 hours under a nitrogen atmosphere to obtain a stream B.

[0053] Calcium oxide was slowly added to deionized water containing 5% ethanol, and was stirred rapidly. Then stream B was slowly added, followed by the slow addition of carboxymethyl cellulose and silica sol. The mass ratio of solvent to calcium oxide was 20:1 based on the mass of calcium oxide, the weight ratio of stream B to calcium oxide was 1.5:1, the dry basis content of carboxymethyl cellulose was 5%, and the dry basis content of silica sol was 1%. The above materials were prepared into microspheres, and were dried at 150°C. Then the material was kept at a constant temperature of 500°C for 5 hours under a nitrogen atmosphere. The material was put into a microwave calcination furnace, and was treated at a power of 400W / (g of material) for 1 hour under an argon atmosphere. The material was kept at a constant temperature of 850°C for 0.5 hours under a nitrogen atmosphere containing 5% oxygen to obtain a calcium-based CO2 adsorbent.

[0054] Example 2

[0055] Potassium silicate was slowly added to deionized water with rapid stirring and the pH was adjusted to 2-3 with nitric acid to obtain stream A. Activated carbon, nickel nitrate, and zirconium nitrate were slowly added to stream A, with the content of hexamethylenetetramine being 15%, the content of nickel nitrate being 0.15%, and the content of zirconium nitrate being 9%, based on the mass of tetraethyl orthosilicate, and the mass ratio of activated carbon to tetraethyl orthosilicate being 1:1. Drying was performed at 120°C, and then the material was kept at a constant temperature of 350°C in a hydrogen atmosphere for 10 hours to obtain stream B.

[0056] Calcium lactate was slowly added to deionized water containing 80% butanol with rapid stirring, then stream B was slowly added, and then microcrystalline cellulose and aluminum dihydrogen phosphate were slowly added. The mass ratio of solvent to calcium lactate was 7:1, the weight ratio of stream B to calcium lactate was 0.5:1, the dry basis content of microcrystalline cellulose was 9%, and the dry basis content of aluminum dihydrogen phosphate was 1%, based on the mass of calcium lactate. The material was prepared into microspheres, dried at 120°C, and then kept at a constant temperature of 800°C in a nitrogen atmosphere for 1 hour. The material was placed in a microwave calcination furnace and treated at a power of 1000 W / (g of material) in an argon atmosphere for 0.5 hours. The material was kept at a constant temperature of 450°C in an oxygen atmosphere for 8 hours to obtain a calcium-based CO2 adsorbent.

[0057] Example 3

[0058] Hexamethylenetetramine was added to deionized water containing 50% propanol with rapid stirring, tetraethyl orthosilicate was slowly added, and the pH was adjusted to 8-9 with ammonia water to obtain stream A. Activated carbon (specific surface area of about 700 m 2 / g), nickel nitrate, and zirconium nitrate were slowly added to stream A, with the content of hexamethylenetetramine being 15%, the content of nickel nitrate being 0.15%, and the content of zirconium nitrate being 9%, based on the mass of tetraethyl orthosilicate, and the mass ratio of activated carbon to tetraethyl orthosilicate being 1:1. Drying was performed at 120°C, and then the material was kept at a constant temperature of 350°C in a hydrogen atmosphere for 10 hours to obtain stream B.

[0059] Calcium nitrate was slowly added to deionized water with rapid stirring, then stream B was slowly added, and then silica sol was slowly added. The mass ratio of solvent to calcium nitrate was 15:1, the weight ratio of stream B to calcium nitrate was 0.35:1, and the dry basis content of silica sol was 0.5%, based on the mass of calcium nitrate. The material was prepared into microspheres, dried at 120°C, and then kept at a constant temperature of 600°C in a nitrogen atmosphere for 2 hours. The material was placed in a microwave calcination furnace and treated at a power of 500 W / (g of material) in an argon atmosphere for 1 hour. The material was kept at a constant temperature of 650°C in an air atmosphere for 1 hour to obtain a calcium-based CO2 adsorbent.

[0060] Example 4

[0061] Formamide was added to deionized water containing 70% ethanol, stirred rapidly, and tetrapropyl orthosilicate was added slowly, and the pH was adjusted to 9-10 with ammonia water to obtain stream A. Semi-coke, aluminum nitrate were added slowly to stream A, and the formamide content was 10% and the aluminum nitrate content was 5% based on the mass of tetrapropyl orthosilicate, and the mass ratio of semi-coke to tetrapropyl orthosilicate was 0.3:1. Solid-liquid separation was performed, and drying was performed at 100°C, and then constant temperature was maintained at 750°C for 3 hours in a propane atmosphere to obtain stream B.

[0062] Calcium gluconate was added slowly to deionized water containing 10% glycerol, stirred rapidly, and then stream B was added slowly, and then sesbania powder and carboxymethyl cellulose were added slowly. The mass ratio of solvent to calcium gluconate was 3:1 based on the mass of calcium gluconate, the weight ratio of stream B to calcium gluconate was 0.25:1, the dry basis content of sesbania powder was 5%, and the dry basis content of carboxymethyl cellulose was 5%. The above materials were prepared into microspheres, and drying was performed at 100°C. The above materials were placed in a microwave calcination furnace, and treated at a power of 150 W / (g of materials) for 3 hours in an argon atmosphere. The above materials were placed in a nitrogen atmosphere containing 75% oxygen, and constant temperature was maintained at 600°C for 0.5 hours to obtain a calcium-based CO2 adsorbent.

[0063] Comparative Example 1

[0064] Hexamethylenetetramine was added to deionized water containing 50% propanol, stirred rapidly, and tetraethyl orthosilicate was added slowly, and the pH was adjusted to 8-9 with ammonia water to obtain stream A. Activated carbon (specific surface area of about 700 m 2 / g) was added slowly to stream A, and the hexamethylenetetramine content was 15% and the mass ratio of activated carbon to tetraethyl orthosilicate was 1:1 based on the mass of tetraethyl orthosilicate. Drying was performed at 120°C, and then constant temperature was maintained at 350°C for 10 hours in a hydrogen atmosphere to obtain stream B.

[0065] Calcium nitrate was added slowly to deionized water, stirred rapidly, and then stream B was added slowly, and then silica sol was added slowly. The mass ratio of solvent to calcium nitrate was 15:1 based on the mass of calcium nitrate, the weight ratio of stream B to calcium nitrate was 0.35:1, and the dry basis content of silica sol was 0.5%. The above materials were prepared into microspheres, and drying was performed at 120°C, and then constant temperature was maintained at 600°C for 2 hours in a nitrogen atmosphere. The above materials were placed in a microwave calcination furnace, and treated at a power of 500 W / (g of materials) for 1 hour in an argon atmosphere. The above materials were placed in an air atmosphere, and constant temperature was maintained at 650°C for 1 hour to obtain a calcium-based CO2 adsorbent.

[0066] Comparative Example 2

[0067] SiC powder, alumina, yttria, carbon black were mixed and ground to obtain stream A. Among them, based on the mass of SiC powder, alumina was 5%, yttria was 2%, and carbon black was 10%.

[0068] Calcium nitrate was slowly added to deionized water, stirred rapidly, then stream A was slowly added, and then silica sol was slowly added. Among them, based on the mass of calcium nitrate, the mass ratio of solvent to calcium nitrate was 5:1, the weight ratio of stream A to calcium nitrate was 0.1:1, and the dry basis content of silica sol was 0.5%. The above materials were prepared into microspheres, dried at 120°C, and then kept at 600°C for 2 hours in a nitrogen atmosphere. The above materials were put into a microwave calcination furnace and treated at a power of 500W / (g of material) for 3 hours in an argon atmosphere. The above materials were kept at 650°C for 1 hour in an air atmosphere to obtain a calcium-based CO2 adsorbent.

[0069] Comparative Example 3

[0070] Hexamethylenetetramine was added to deionized water containing 50% propanol, stirred rapidly, and then tetraethyl orthosilicate was slowly added. The pH was adjusted to 8-9 with ammonia water to obtain stream A. Activated carbon (specific surface area about 700m 2 / g), nickel nitrate, and zirconium nitrate were slowly added to stream A. Based on the mass of tetraethyl orthosilicate, the content of hexamethylenetetramine was 15%, the content of nickel nitrate was 0.15%, the content of zirconium nitrate was 9%, and the mass ratio of activated carbon to tetraethyl orthosilicate was 1:1. Drying was carried out at 120°C, and then stream B was obtained by keeping at 350°C for 10 hours in a hydrogen atmosphere.

[0071] Calcium nitrate was slowly added to deionized water, stirred rapidly, then stream B was slowly added, and then silica sol was slowly added. Among them, based on the mass of calcium nitrate, the mass ratio of solvent to calcium nitrate was 15:1, the weight ratio of stream B to calcium nitrate was 0.35:1, and the dry basis content of silica sol was 0.5%. The above materials were prepared into microspheres, dried at 120°C, and then kept at 1700°C for 7 hours in an argon atmosphere. The above materials were kept at 650°C for 1 hour in an air atmosphere to obtain a calcium-based CO2 adsorbent.

[0072] Comparative Example 4

[0073] Hexamethylenetetramine was added to deionized water containing 50% propanol, stirred rapidly, and then tetraethyl orthosilicate was slowly added. The pH was adjusted to 8-9 with ammonia water to obtain stream A. Nickel nitrate and zirconium nitrate were slowly added to stream A. Based on the mass of tetraethyl orthosilicate, the content of hexamethylenetetramine was 15%, the content of nickel nitrate was 0.15%, and the content of zirconium nitrate was 9%. Then stream B was obtained by keeping at 350°C for 10 hours in a hydrogen atmosphere.

[0074] The calcium nitrate was slowly added into deionized water, stirred rapidly, then slowly added into stream B, and then slowly added into silica sol. Among them, the mass ratio of solvent to calcium nitrate was 15:1, the weight ratio of stream B to calcium nitrate was 0.1:1, and the dry basis content of silica sol was 0.5% based on the mass of calcium nitrate. The above materials were prepared into microspheres, dried at 120°C, and then kept at 600°C for 2 hours in a nitrogen atmosphere. The above materials were put into a microwave calcination furnace and treated at a power of 500W / (g of material) for 1 hour in an argon atmosphere. The above materials were kept at 650°C for 1 hour in an air atmosphere to obtain a calcium-based CO2 adsorbent.

[0075] Evaluation of adsorbent performance:

[0076] The mass attrition rate of the calcium-based CO2 adsorbents prepared from Examples 1-4 and Comparative Examples 1-4 was determined using a KM-5A type particle attrition tester, the determination rotation speed was 25r / min, and the test time was 10h. The results are shown in Table 1.

[0077] The CO2 adsorption capacity of the calcium-based CO2 adsorbents prepared from Examples 1-4 and Comparative Examples 1-4 was determined using a thermal gravimetric analyzer (TGA), the determination conditions were: adsorption temperature was 650°C, desorption temperature was 800°C, cycle number was 100 times, and the average value was taken. The CO2 adsorption capacity of the adsorbent is shown in Table 1.

[0078] Table 1 Mass attrition rate of adsorbent and CO2 adsorption capacity of adsorbent

[0079] No. Mass wear rate / % Adsorption capacity / g CO2 / g 吸附剂 ]] Example 1 0.33 0.37 Example 2 0.59 0.41 Example 3 0.56 0.42 Example 4 0.47 0.39 Comparative Example 1 2.16 0.30 Comparative Example 2 0.46 0.12 Comparative Example 3 0.52 0.06 Comparative Example 4 9.85 0.16

Claims

1. A method for preparing a calcium-based CO2 adsorbent, comprising the following steps: (1) mixing a silicon-containing compound with a solvent A, and then adjusting the pH value of the system to obtain a stream A; the silicon-containing compound is selected from one or more of soluble silicate, alkoxysilane, and silicon tetrachloride; the solvent A is water or a mixture of water and an organic solvent; the solvent A further comprises component A, wherein the component A is one or more of silicone oil, hexamethylenetetramine, formamide, N,N-dimethylformamide, and polyethylene glycol; the polyethylene glycol has a molecular weight of 200-20,000; (2) adding a metal cation to the stream A to obtain a stream B; the metal cation is selected from one or more of aluminum, iron, magnesium, copper, silver, nickel, zirconium, cerium, lanthanum, yttrium, manganese, titanium, ytterbium, and neodymium; the carbon source is one or more of activated carbon, carbon black, and semi-coke; the heat treatment comprises two steps of drying and calcination, and the calcination is performed in the presence of a reducing atmosphere; (3) mixing the stream B, a calcium source, and a solvent B uniformly, then introducing an additive B, and drying to obtain a stream C, which is further treated in the presence of microwaves; the additive B is selected from one or more of carboxymethyl cellulose, hydroxyethyl cellulose, microcrystalline cellulose, chitosan, sesbania gum, hydroxypropyl methyl cellulose, polyvinyl alcohol, silica sol, and aluminum dihydrogen phosphate; the microwave treatment is performed in the presence of an inert gas, and the microwave power is 10-1,000 W / (g of material); and (4) heat-treating the material obtained in step (3) in the presence of an oxygen-containing atmosphere to obtain the calcium-based CO2 adsorbent. The soluble silicate in step (1) is one or more of sodium silicate, lithium silicate, potassium silicate, and ammonium silicate; and the alkoxysilane is one or more of methyl orthosilicate, ethyl orthosilicate, propyl orthosilicate, isopropyl orthosilicate, dimethyldiethoxysilane, methyltriethoxysilane, methyltrimethoxysilane, vinyltriethoxysilane, and n-octyltriethoxysilane. (2) mixing the stream A, the additive A, and the carbon source, and obtaining the stream B after heat treatment; the additive A is one or more of metal nitrate, metal carbonate, metal phosphate, metal organic acid salt, and metal chloride, wherein, The silicon-containing compound in step (1) is selected from one or more of sodium silicate, ethyl orthosilicate, and dimethyldiethoxysilane. The organic solvent in step (1) is an alcohol selected from one or more of ethanol, methanol, propanol, butanol, ethylene glycol, propylene glycol, glycerol, and butanediol; and when the solvent A is a mixture of water and an alcohol, the concentration of the alcohol is 1wt%-80wt%. The alcohol is ethanol.

2. The method of producing a calcium-based CO2 adsorbent according to claim 1, wherein, The additive A in step (2) is selected from one or more of aluminum nitrate, iron nitrate, magnesium nitrate, copper nitrate, silver nitrate, nickel nitrate, zirconium nitrate, cerium nitrate, lanthanum nitrate, yttrium nitrate, manganese nitrate, titanium tetrachloride, ytterbium nitrate, neodymium nitrate, basic aluminum acetate, magnesium acetate, magnesium oxalate, and zirconium acetate.

3. The method of producing a calcium-based CO2 adsorbent according to claim 1, wherein, The additive A in step (2) is one or more of aluminum nitrate, iron nitrate, magnesium nitrate, copper nitrate, silver nitrate, and nickel nitrate.

4. The method of producing a calcium-based CO2 adsorbent according to claim 1, wherein, The dry basis content of the additive A is 0.01wt%-10.0wt% based on the mass of the silicon-containing compound; and the mass ratio of the carbon source to the silicon-containing compound is 0.1:1-10:

1.

5. The method of producing a calcium-based CO2 adsorbent according to claim 4, wherein, ​ 6. The method of making a calcium-based CO2 adsorbent according to claim 1, wherein, ​ 7. The method of making a calcium-based CO2 adsorbent according to claim 1, wherein, ​ 8. The method of making a calcium-based CO2 adsorbent according to claim 1, wherein, The carbon source in step (2) is activated carbon having a specific surface area of greater than 200 m 2 / g.

9. The method of making a calcium-based CO2 adsorbent according to claim 1, wherein, ​ 10. The method of making a calcium-based CO2 adsorbent according to claim 1, wherein, The drying temperature in step (2) is 100-150℃, the calcination temperature is 350-900℃, and the calcination time is 0.2-10 hours; the reducing atmosphere is any one of a reducing gas, a mixed gas of a reducing gas and an inert atmosphere; the reducing gas is one or more of hydrogen, carbon monoxide, methane, and C2-C4 gas; the volume content of the reducing gas in the mixed gas is 0.5%-99.5%; and the inert atmosphere is nitrogen and / or an inert gas.

11. The method of making a calcium-based CO2 adsorbent according to claim 10, wherein, The reducing gas is hydrogen and / or methane.

12. The method of making a calcium-based CO2 adsorbent according to claim 1, wherein, The calcium source in step (3) is one or more of calcium oxide, calcium hydroxide, and calcium salt.

13. The method of making a calcium-based CO2 adsorbent according to claim 1, wherein, The calcium source in step (3) is one or more of calcium oxide, calcium oxalate, calcium gluconate, calcium hydroxide, calcium carbonate, calcium acetate, calcium propionate, calcium acetylacetonate, calcium lactate, calcium formate, calcium citrate, and calcium nitrate.

14. The method of making a calcium-based CO2 adsorbent according to claim 1, wherein, The calcium source in step (3) is one or more of calcium oxide, calcium oxalate, and calcium nitrate.

15. The method of making a calcium-based CO2 adsorbent according to claim 1, wherein, The solvent B in step (3) is water and / or an organic solvent, and the organic solvent is an alcohol; the alcohol is an alcohol with 1-4 carbon atoms; and when the solvent B is a mixed solvent of water and an organic solvent, the concentration of the organic solvent is 1wt%-80wt%.

16. The method of making a calcium-based CO2 adsorbent according to claim 15, wherein, The alcohol is selected from one or more of ethanol, methanol, propanol, butanol, ethylene glycol, propylene glycol, glycerol, and butylene glycol.

17. The method of making a calcium-based CO2 adsorbent according to claim 15, wherein, The alcohol is ethanol.

18. The method of making a calcium-based CO2 adsorbent according to claim 1, wherein, The auxiliary B in step (3) is one or more of carboxymethyl cellulose, sesbania powder, polyvinyl alcohol, and silica sol and a solution thereof.

19. The method of making a calcium-based CO2 adsorbent according to claim 1, wherein, In step (3), the mass ratio of the solvent B to the calcium source is 0.2:1-20:1, the mass ratio of the stream B to the calcium source is 0.01:1-2:1, and the dry basis content of the auxiliary B is 0.5wt%-10wt%, based on the mass of the calcium source.

20. The method of making a calcium-based CO2 adsorbent according to claim 1, wherein, The drying temperature in step (3) is 100-150℃.

21. The method of making a calcium-based CO2 adsorbent according to claim 1, wherein, After drying in step (3), calcination is performed at a temperature of 350-900℃ for 1-10 hours in the presence of an inert atmosphere, and the inert atmosphere is nitrogen and / or an inert gas.

22. The method of making a calcium-based CO2 adsorbent according to claim 1, wherein, The microwave power in step (3) is 100-500W / (g of material), and the microwave treatment time is 0.1-10 hours.

23. The method of making a calcium-based CO2 adsorbent of claim 22, wherein, The microwave treatment time is 0.1-1 hour.

24. The method of making a calcium-based CO2 adsorbent according to claim 1, wherein, The heat treatment temperature in step (4) is 500-1300℃, and the heat treatment time is 0.5-8 hours.

25. The method of making a calcium-based CO2 adsorbent according to claim 24, wherein, The heat treatment temperature in step (4) is 500-800℃.

26. A calcium-based CO2 adsorbent obtained by the preparation method of any one of claims 1-25.

27. Use of the calcium-based CO2 adsorbent of claim 26 in adsorbing CO2.