A silicon carbide doped calcium-based co2 adsorbent and a method of making the same

Abstract

The application provides a silicon carbide doped calcium-based CO2 adsorbent and a preparation method thereof. The preparation method comprises the following steps: (1) mixing a carbon source and a first additive solution, then introducing a silicon source, and further drying and calcining to obtain a first material; (2) mixing a calcium source, a solvent and the first material, then introducing a second additive, and drying to obtain a second material; and (3) treating the second material under microwave conditions to obtain the silicon carbide doped calcium-based CO2 adsorbent. The application also provides a silicon carbide doped calcium-based CO2 adsorbent obtained by using the above preparation method. The adsorbent is resistant to wear, has high adsorption capacity, high microwave absorption rate, is resistant to sintering and carbon deposition, and can be used for a long time.

Description

TECHNICAL FIELD

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

[0002] Calcium-based CO2 adsorbent, as a high-temperature adsorbent with fast adsorption rate, high capacity, low price and convenient operation, has been concerned. It is not only the most promising adsorbent in the current CO2 capture technology, but also can be applied to various chemical processes involving CO2 generation or participation, to affect the reaction equilibrium and change the reaction path by using the absorption or release of CO2. For example, in the processes of biomass gasification, hydrogen production from methane and hydrogen production from ethanol reforming, the application of calcium-based CO2 adsorbent can improve the concentration of hydrogen, improve the quality of gas, reduce the cost and energy consumption.

[0003] Calcium-based CO2 adsorbent completes the adsorption and desorption cycle of CO2 through the carbonation / calcination regeneration process. Since the Tammann temperature of CaCO3 is lower than the regeneration temperature of calcium-based adsorbent, after multiple cycles, the adsorbent particles begin to sinter and fuse, causing a significant decrease in specific surface area and a rapid decrease in adsorption capacity. At the same time, the molar volume of CaCO3 is 36.9 cm 3 / mol, while that of CaO is 16.7 cm 3 / mol, so the pores of calcium-based adsorbent are prone to collapse due to local volume change during the cycle, and the structural stability is destroyed. Based on the above reasons, the carbonation conversion rate of calcium-based adsorbent rapidly decays with the increase of cycle number. To solve this problem, researchers mainly modify the adsorbent by doping inert components with high Tammann temperature such as Zr, to provide a supporting skeleton for the adsorbent and relieve its sintering, and meanwhile, adopt hollow structure and other ways to regulate its morphology and maintain its structural properties. After the above modification, the adsorption stability and structural stability of calcium-based adsorbent are improved, but its strength is improved limitedly, far from meeting the requirements of application in gasification or hydrogen production processes, especially in mobile bed and fluidized bed.

[0004] CN109012008A discloses a method of mixing and grinding rare earth dopant powder obtained by pretreatment and calcined calcium-based precursor to obtain calcium-based adsorbent, to prepare calcium-based CO2 adsorbent doped with rare earth waste. CN108499515A discloses a method of preparing calcium-based adsorbent by mixing and pre-sintering Li4SiO4 prepared by using Li2CO3 and fly ash or SiO2 as raw materials by high-temperature solid-phase method and calcium-based precursor, to prepare calcium-based adsorbent doped with Li4SiO4. The above patents use the method of direct mixing and doping to prepare calcium-based adsorbent, and the mechanical strength, especially the high-temperature wear resistance, is weak. SUMMARY

[0005] In view of the deficiencies in the prior art, the present application aims to provide a silicon carbide-doped calcium-based CO2 adsorbent and a preparation method thereof. The adsorbent is resistant to wear, has high adsorption capacity, high microwave absorption rate, and is resistant to sintering and carbon deposition, and can be used for a long time.

[0006] The present application provides a preparation method of a silicon carbide-doped calcium-based CO2 adsorbent, which comprises the following steps:

[0007] (1) Under contact conditions, mix a carbon source and a first additive solution, then introduce a silicon source, and further dry and calcine to obtain a first material;

[0008] (2) Under contact conditions, mix a calcium source, a solvent, and the first material obtained in step (1), then introduce a second additive, and dry to obtain a second material;

[0009] (3) Under microwave conditions, treat the second material obtained in step (2) to obtain a silicon carbide-doped calcium-based CO2 adsorbent.

[0010] Further, in the above preparation method of the silicon carbide-doped calcium-based CO2 adsorbent, as a specific embodiment, the first additive in step (1) is one or more of a nitrate, a carbonate, a phosphate, an organic acid salt, and a chloride of a first metal, wherein the first metal can be selected from one or more of aluminum, iron, magnesium, copper, silver, nickel, zirconium, cerium, lanthanum, yttrium, manganese, titanium, ytterbium, and neodymium; the first additive is further preferably 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, and is more preferably one or more of aluminum nitrate, iron nitrate, magnesium nitrate, copper nitrate, silver nitrate, nickel nitrate, and zirconium nitrate.

[0011] Further, in the above preparation method of the silicon carbide-doped calcium-based CO2 adsorbent, as a specific embodiment, the solvent of the first additive solution in step (1) is water and / or an organic solvent; the organic solvent is preferably an alcohol solvent, and can be selected from one or more of ethanol, methanol, propanol, butanol, ethylene glycol, propylene glycol, glycerol, and butylene glycol, and is further preferably ethanol; when the solvent is a mixed solvent of water and an organic solvent, the concentration of the organic solvent is 1wt% to 80wt%.

[0012] Further, in the preparation method of the silicon-doped calcium-based CO2 adsorbent, as a specific embodiment, the pH value of the mixture of the carbon source and the first additive solution can be adjusted to 1-10 before the silicon source is introduced in step (1), and the pH value can be adjusted by adding acid or ammonia water. The acid can be one or more of nitric acid, hydrochloric acid, phosphoric acid, oxalic acid, and citric acid.

[0013] Further, in the preparation method of the silicon-doped calcium-based CO2 adsorbent, as a specific embodiment, the carbon source in step (1) can be one or more of monosaccharide, disaccharide, water-soluble polysaccharide, phenolic resin, water-soluble starch, dextrin, glycerol, furfural, and furfuryl alcohol, and preferably sucrose and / or phenolic resin.

[0014] Further, in the preparation method of the silicon-doped calcium-based CO2 adsorbent, as a specific embodiment, the silicon source in step (1) can be one or more of diatomite, white carbon black, mesoporous silica, nano-silicon dioxide, and silica fume.

[0015] Further, in the preparation method of the silicon-doped calcium-based CO2 adsorbent, as a specific embodiment, the dry content of the first additive is 0.01wt%-10.0wt% based on the mass of the silicon source, and the mass ratio of the carbon source to the silicon source is 0.3:1-10:1.

[0016] Further, in the preparation method of the silicon-doped calcium-based CO2 adsorbent, as a specific embodiment, the drying temperature in step (1) is 100-150°C.

[0017] Further, in the preparation method of the silicon-doped calcium-based CO2 adsorbent, as a specific embodiment, the calcination temperature in step (1) is 350-900°C, and the calcination time is 0.2-10 hours.

[0018] Further, in the preparation method of the silicon-doped calcium-based CO2 adsorbent, as a specific embodiment, the calcination in step (1) is carried out under an inert atmosphere and / or a reducing atmosphere, and preferably under a reducing 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. The reducing atmosphere is any one of a reducing gas and a mixture of a reducing gas and an inert atmosphere. The reducing gas is one or more of hydrogen, carbon monoxide, methane, and C2-C4 gas, and preferably hydrogen and / or methane. In the mixture, the volume content of the reducing gas is 0.5-100%. 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.

[0019] Further, in the preparation method of the silicon carbide-doped calcium-based CO2 adsorbent, as a specific embodiment, the solid-liquid separation is preferably performed before drying in step (1), and the separated solid material is dried.

[0020] Further, in the preparation method of the silicon carbide-doped calcium-based CO2 adsorbent, as a specific embodiment, the calcium source in step (2) is one or more of calcium oxide, calcium hydroxide, and calcium salt, preferably one or more of calcium oxalate, calcium gluconate, calcium hydroxide, calcium oxide, calcium carbonate, calcium acetate, calcium propionate, calcium acetylacetonate, calcium lactate, calcium formate, calcium citrate, and calcium nitrate, and further preferably one or more of calcium oxalate, calcium oxide, and calcium nitrate.

[0021] Further, in the preparation method of the silicon carbide-doped calcium-based CO2 adsorbent, as a specific embodiment, the solvent in step (2) is water and / or an organic solvent; the organic solvent is preferably an alcohol solvent, and can be one or more of ethanol, methanol, propanol, butanol, ethylene glycol, propylene glycol, glycerol, and butylene glycol, and is further preferably ethanol; when the solvent is a mixed solvent of water and an organic solvent, the concentration of the organic solvent is 1wt% to 80wt%.

[0022] Further, in the preparation method of the silicon carbide-doped calcium-based CO2 adsorbent, as a specific embodiment, the second additive in step (2) can be one or more of carboxymethyl cellulose, hydroxyethyl cellulose, microcrystalline cellulose, chitosan, sesbania gum, hydroxypropyl methyl cellulose, polyvinyl alcohol (molecular weight 0.5 to 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 to 150,000), and silica sol and solutions thereof.

[0023] Further, in the preparation method of the silicon carbide-doped calcium-based CO2 adsorbent, as a specific embodiment, in step (2), the mass ratio of the solvent to the calcium source is 0.2:1 to 20:1, the weight ratio of the first material to the calcium source is 0.01:1 to 2:1, and the dry basis content of the second additive is 0.5wt% to 10wt%, based on the mass of the calcium source.

[0024] Furthermore, in the above-mentioned method for preparing silicon carbide-doped calcium-based CO2 adsorbent, as a specific embodiment, step (2) preferably involves a molding process 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. It can be any shape such as cylindrical strip, clover shape, four-leaf clover shape, or sphere, preferably sphere. The spherical molding method can be one or more of extrusion ball-throwing molding, rolling molding, and spray drying molding.

[0025] Furthermore, in the above-mentioned method for preparing silicon carbide-doped calcium-based CO2 adsorbent, as a specific embodiment, the drying temperature in step (2) is 100-150°C.

[0026] Furthermore, in the above-mentioned method for preparing silicon carbide-doped calcium-based CO2 adsorbent, as a specific embodiment, after drying in step (2), a calcination treatment can be performed. The calcination temperature is 350-900℃, the calcination time is 1-10 hours, and the calcination is carried out in the presence of an inert atmosphere, wherein 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.

[0027] Furthermore, in the above-mentioned method for preparing silicon carbide-doped calcium-based CO2 adsorbent, as a specific embodiment, the microwave heating power in step (3) is 10-1000W / (g material), preferably 100-500W / (g material); the treatment time is 0.1-10 hours, preferably 0.1-1 hours; the microwave treatment is further preferably carried out in the presence of an inert gas, wherein the inert gas is one or more of helium, neon, argon, krypton, and xenon.

[0028] Furthermore, in the above-mentioned method for preparing silicon carbide-doped calcium-based CO2 adsorbent, as a specific embodiment, the preparation method further includes step (4), which involves heat-treating the material obtained in step (3) under an oxygen-containing atmosphere. The oxygen-containing atmosphere can be any one of air, oxygen, or a mixture of oxygen and an inert atmosphere, wherein the oxygen volume content in the mixture is 5-99.99%; the inert atmosphere is nitrogen and / or an inert gas, wherein the inert gas is one or more of helium, neon, argon, krypton, and xenon. The heat treatment temperature is 500-1300℃, preferably 500-800℃, and the heat treatment time is 0.5-8 hours.

[0029] A second aspect of the present invention provides a silicon carbide-doped calcium-based CO2 adsorbent, wherein the silicon carbide-doped calcium-based CO2 adsorbent is obtained by the preparation method provided above.

[0030] Further, as a specific embodiment of the above-mentioned silicon carbide-doped calcium-based CO2 adsorbent, the silicon carbide-doped calcium-based CO2 adsorbent comprises calcium oxide, silicon carbide, a compound of a first metal, and silicon dioxide, the content of the silicon carbide is 0.1-45 wt%, the content of the compound of the first metal is 0.01-5 wt%, and the content of the silicon dioxide is 0.01-5 wt% based on the weight of the adsorbent.

[0031] Compared with the prior art, the silicon carbide-doped calcium-based CO2 adsorbent and the preparation method thereof have the following advantages:

[0032] 1. In the preparation method of the silicon carbide-doped calcium-based CO2 adsorbent, silicon carbide is introduced through in-situ reaction. Silicon carbide has excellent mechanical strength, chemical stability and thermal stability, and is an inert component with a high Tamman temperature. The silicon carbide is used for doping and modifying CaO. In the subsequent high-temperature regeneration process, the silicon carbide can effectively alleviate and prevent the sintering of CaO, so that the CaO can maintain good structural properties, improve the strength and wear resistance, and improve the CO2 adsorption performance, which is beneficial to the long-term cyclic use of the adsorbent.

[0033] 2. In the preparation method of the silicon carbide-doped calcium-based CO2 adsorbent, the silicon source plays a role of a template to a certain extent, guides the formation of the surface morphology of the adsorbent, and inhibits the growth of CaO active particles. The carbon source plays a role of a pore-forming agent to a certain extent, promotes the formation of a developed pore structure of the adsorbent, buffers the local volume change of the adsorbent in the adsorption and desorption cycle to a certain extent, ensures the structural stability of the adsorbent, and is beneficial to improving the specific surface area and the diffusion of CO2, and thus promoting the adsorption of CO2.

[0034] 3. In the preparation method of the silicon carbide-doped calcium-based CO2 adsorbent, the metal particles are formed on the surface of the silicon source by the first additive. Firstly, the metal particles can have a strong interaction with microwaves, the electromagnetic field can cause the movement of electrons to generate an induced eddy current, the eddy current is limited in the medium, and thus a Joule heating effect is generated, and even a microwave discharge phenomenon is caused, which all cause the metal particles to be heated sharply, and the microwave selective heating effect is strengthened. Secondly, the metal particles can be oxidized to generate an inert component with a high Tamman temperature, which further alleviates and prevents the sintering of CaO particles. Moreover, the introduction of the metal active components (such as nickel, iron and cobalt) can catalyze the reaction between the carbon source and the silicon source, reduce the synthesis difficulty of the silicon carbide, and control the structure and morphology of the silicon carbide.

[0035] 4、The preparation method of the silicon carbide doped calcium-based CO2 adsorbent provided by the application, the material is heated under microwave conditions, the hot spot effect, selective heating effect and other non-thermal effects of the microwave are used to solve the contradiction between the high generation temperature of silicon carbide, the difficulty in processing and molding and the maintenance of CaO particle activity, and the silicon carbide is generated in situ. In the preparation process, the carbon, metal particles and newly generated silicon carbide form hot spots, reduce the reaction temperature, and promote the rapid generation of silicon carbide and the formation of the support skeleton. The dielectric properties of carbon, metal particles, silicon carbide and calcium oxide are very different. Carbon, metal particles and silicon carbide belong to wave-absorbing substances, while calcium oxide belongs to wave-transparent substances. The heating rate of the former three is much higher than that of the latter in the microwave field. This selective heating helps to overcome the problem of CaO active particle growth caused by the high generation temperature of silicon carbide. DETAILED DESCRIPTION

[0036] The specific content and effects of the method of the application are further illustrated by specific embodiments, but the scope of the application is not limited by the embodiments. In the application, the molecular weight of the polyvinyl alcohol is the viscosity average molecular weight.

[0037] The specific embodiments of the application are 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.

[0038] 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.

[0039] 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.

[0040] 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 element or component, but not exclude other elements or components. In this text, all numerical values of parameters (such as quantities or conditions) should be understood to be modified by the term "about" in all cases, whether the term "about" actually appears before the numerical value or not.

[0041] Unless otherwise explicitly stated, all percentages, parts, ratios, etc. mentioned in the specification are based on weight, and the pressure is gauge pressure.

[0042] In the context of the present specification, any two or more embodiments of the present application can be combined in an arbitrary manner, and the technical solutions thus formed are part of the original disclosure of the present specification and also fall within the protection scope of the present application.

[0043] In the following examples and comparative examples, the specific conditions not specified are carried out according to the conventional conditions or the conditions recommended by the manufacturer. The reagents or instruments used are not specified by the manufacturer, and are all conventional products that can be obtained by market purchase.

[0044] Example 1

[0045] Sucrose, aluminum nitrate were slowly added into deionized water containing 5% ethanol, stirred rapidly, and adjusted to pH 1 with nitric acid, and then nano-silica was slowly added. Among them, the content of aluminum nitrate was 10% based on the mass of nano-silica, and the mass ratio of sucrose to nano-silica was 6:1. Drying was carried out at 120°C, and then constant temperature was maintained at 600°C for 2 hours in a hydrogen atmosphere to obtain a first material.

[0046] Calcium oxalate was slowly added into deionized water containing 1% ethanol, stirred rapidly, and then the first material was slowly added, and then amaranth powder and silica sol were slowly added. Among them, the mass ratio of solvent to calcium oxalate was 10:1 based on the mass of calcium oxalate, the weight ratio of the first material to calcium oxalate was 0.25:1, the dry basis content of amaranth powder was 5%, and the dry basis content of silica sol was 0.5%. The above materials were prepared into microspheres, dried at 120°C, and then constant temperature was maintained at 600°C for 3 hours in a nitrogen atmosphere. The above material was sent into a microwave calcination furnace and treated at a power of 500W / (g of material) for 1 hour in an argon atmosphere. The above material was constant temperature maintained at 600°C for 2 hours in an air atmosphere to obtain a calcium-based CO2 adsorbent.

[0047] Example 2

[0048] Starch, iron nitrate was slowly added into deionized water containing 20% methanol, stirred rapidly, and adjusted to pH 3 with phosphoric acid, and then mesoporous silica was slowly added. Among them, the content of iron nitrate was 1% based on the mass of mesoporous silica, and the mass ratio of starch to mesoporous silica was 2:1. Solid-liquid separation was carried out, dried at 150°C, and then constant temperature was maintained at 900°C for 1 hour in an ethane atmosphere to obtain a first material.

[0049] Calcium acetylacetonate was slowly added to deionized water containing 80% methanol, stirred rapidly, then the first material was slowly added, and then aluminum dihydrogen phosphate was slowly added. Among them, the mass ratio of solvent to calcium acetylacetonate was 20:1, the weight ratio of the first material to calcium acetylacetonate was 0.1:1, and the dry basis content of aluminum dihydrogen phosphate was 0.5% based on the mass of calcium acetylacetonate. The above material was prepared into microspheres, dried at 150°C, and then kept at 350°C for 10 hours in a nitrogen atmosphere. The above material was put into a microwave calcination furnace and treated at a power of 1000W / (g of material) for 0.5 hours in an argon atmosphere. The above material was kept at 650°C for 1 hour in a nitrogen atmosphere containing 50% oxygen to obtain a calcium-based CO2 adsorbent.

[0050] Example 3

[0051] Fructose and magnesium nitrate were slowly added to deionized water, stirred rapidly, and then white carbon black was slowly added. Among them, the content of magnesium nitrate was 3% based on the mass of white carbon black, and the mass ratio of fructose to white carbon black was 10:1. Drying was carried out at 100°C, and then the first material was obtained by keeping at 600°C for 4 hours in a methane atmosphere.

[0052] Calcium nitrate was slowly added to deionized water, stirred rapidly, then the first material was slowly added, and then the first material was slowly added. Among them, the mass ratio of solvent to calcium nitrate was 5:1, the weight ratio of the first material to calcium nitrate was 0.5:1, the dry basis content of sesbania powder was 2%, and the dry basis content of polyvinyl alcohol (average molecular weight 22000) was 2% based on the mass of calcium nitrate. The above material was prepared into microspheres, dried at 120°C, and then kept at 700°C for 1 hour in a nitrogen atmosphere. The above material was put into a microwave calcination furnace and treated at a power of 800W / (g of material) for 0.5 hours in an argon atmosphere. The above material was kept at 800°C for 1 hour in an air atmosphere to obtain a calcium-based CO2 adsorbent.

[0053] Example 4

[0054] Phenolic resin and zirconium nitrate were slowly added to deionized water containing 65% ethanol, stirred rapidly, and then adjusted to pH 5 with oxalic acid, and then diatomite was slowly added. Among them, the content of zirconium nitrate was 5% based on the mass of diatomite, and the mass ratio of phenolic resin to diatomite was 6:1. Drying was carried out at 120°C, and then the first material was obtained by keeping at 600°C for 8 hours in a hydrogen atmosphere.

[0055] Calcium oxide was slowly added into deionized water containing 15% ethanol, stirred rapidly, then the first material was slowly added, then carboxymethyl cellulose and silica sol were slowly added. Among them, the mass ratio of solvent to calcium oxide was 15:1, the weight ratio of the first material to calcium oxide was 1.8:1, the dry basis content of carboxymethyl cellulose was 5%, and the dry basis content of silica sol was 0.5% based on the mass of calcium oxide. The above materials were prepared into microspheres, dried at 120°C, then kept at 800°C for 1 hour in a nitrogen atmosphere. The above materials were put into a microwave calcination furnace, treated at a power of 100W / (g of material) for 3 hours in an argon atmosphere. The above materials were kept at 350°C for 8 hours in an oxygen atmosphere to obtain a calcium-based CO2 adsorbent.

[0056] Comparative Example 1

[0057] Sucrose was slowly added into deionized water containing 5% ethanol, stirred rapidly, and the pH was adjusted to 1 with nitric acid, then nano-silicon dioxide was slowly added. Among them, the mass ratio of sucrose to nano-silicon dioxide was 6:1 based on the mass of nano-silicon dioxide. Dried at 120°C, then kept at 600°C for 2 hours in a hydrogen atmosphere to obtain the first material.

[0058] Calcium oxalate was slowly added into deionized water containing 1% ethanol, stirred rapidly, then the first material was slowly added, then amaranth powder and silica sol were slowly added. Among them, the mass ratio of solvent to calcium oxalate was 10:1, the weight ratio of the first material to calcium oxalate was 0.25:1, the dry basis content of amaranth powder was 5%, and the dry basis content of silica sol was 0.5% based on the mass of calcium oxalate. The above materials were prepared into microspheres, dried at 120°C, then kept at 600°C for 3 hours in a nitrogen atmosphere. The above materials were put into a microwave calcination furnace, treated at a power of 500W / (g of material) for 1 hour in an argon atmosphere. The above materials were kept at 600°C for 2 hours in an air atmosphere to obtain a calcium-based CO2 adsorbent.

[0059] Comparative Example 2

[0060] SiC micro powder, alumina, yttrium oxide, and carbon black were mixed and ground to obtain the first material. Among them, the mass ratio of alumina to SiC micro powder was 5%, the mass ratio of yttrium oxide to SiC micro powder was 2%, and the mass ratio of carbon black to SiC micro powder was 10%.

[0061] The calcium oxalate was slowly added into deionized water containing 1% ethanol, stirred rapidly, then the first material was slowly added, then the sesbania powder and silica sol were slowly added. Among them, the mass ratio of solvent to calcium oxalate was 5:1, the weight ratio of the first material to calcium oxalate was 0.15:1, the dry basis content of sesbania powder was 5%, and the dry basis content of silica sol was 0.5% based on the mass of calcium oxalate. The above materials were prepared into microspheres, dried at 120°C, then kept constant temperature at 600°C for 3 hours in a nitrogen atmosphere. The above materials were put into a microwave calcination furnace, treated at a power of 500W / (g of material) for 3 hours in an argon atmosphere. The above materials were kept constant temperature at 600°C for 2 hours in an air atmosphere, to obtain a calcium-based CO2 adsorbent.

[0062] Comparative Example 3

[0063] The sucrose and aluminum nitrate were slowly added into deionized water containing 5% ethanol, stirred rapidly, and the pH was adjusted to 1 with nitric acid, then the nanosilica was slowly added. Among them, the aluminum nitrate content was 10%, and the mass ratio of sucrose to nanosilica was 6:1 based on the mass of nanosilica. Dried at 120°C, then kept constant temperature at 600°C for 2 hours in a hydrogen atmosphere, to obtain a first material.

[0064] The calcium oxalate was slowly added into deionized water containing 1% ethanol, stirred rapidly, then the first material was slowly added, then the sesbania powder and silica sol were slowly added. Among them, the mass ratio of solvent to calcium oxalate was 10:1, the weight ratio of the first material to calcium oxalate was 0.25:1, the dry basis content of sesbania powder was 5%, and the dry basis content of silica sol was 0.5% based on the mass of calcium oxalate. The above materials were prepared into microspheres, dried at 120°C, then kept constant temperature at 1700°C for 7 hours in an argon atmosphere. The above materials were kept constant temperature at 600°C for 2 hours in an air atmosphere, to obtain a calcium-based CO2 adsorbent.

[0065] Evaluation of adsorbent performance:

[0066] The mass attrition rate of the calcium-based CO2 adsorbents prepared from Examples 1-4 and Comparative Examples 1-3 was determined by a KM-5A type particle abrasion tester, the rotation speed was 25r / min, and the test time was 10h, and the results are shown in Table 1:

[0067] Table 1 Mass attrition rate of adsorbent

[0068] Catalyst Mass attrition rate / % Example 1 0.62 Example 2 0.51 Example 3 0.43 Example 4 0.39 Comparative Example 1 2.35 Comparative Example 2 0.49 Comparative Example 3 0.57

[0069] The CO2 adsorption capacity of the calcium-based CO2 adsorbents prepared in Examples 1 to 4 and Comparative Examples 1 to 3 was measured using a thermogravimetric analyzer (TGA) under the following conditions: adsorption temperature of 650°C, desorption temperature of 800°C, and 100 cycles, and the average value was obtained, and the results are shown in Table 2.

[0070] Table 2 CO2 adsorption capacity of adsorbents

[0071] Catalyst Adsorption capacity / g CO2 / g 吸附剂 ]] Example 1 0.41 Example 2 0.38 Example 3 0.36 Example 4 0.39 Comparative Example 1 0.31 Comparative Example 2 0.17 Comparative Example 3 0.04

Claims

1. A method for preparing a silicon carbide-doped calcium-based CO2 adsorbent, the method comprising the following steps: (1) under the contacting condition, mixing the carbon source with the first additive solution, then introducing the silicon source, and further drying and calcining to obtain the first material; the first additive is one or more of nitrate, carbonate, phosphate, organic acid salt, and chloride of the first metal, wherein, the first metal is selected from one or more of aluminum, iron, magnesium, copper, silver, nickel, zirconium, cerium, lanthanum, yttrium, manganese, titanium, ytterbium, and neodymium; the solvent of the first additive solution is water and / or an organic solvent; the carbon source is one or more of a monosaccharide, a disaccharide, a water-soluble polysaccharide, a phenolic resin, glycerol, furfural, and furfuryl alcohol; the silicon source is one or more of diatomite, white carbon black, mesoporous silica, nano-silica, and silica fume; and the calcination is performed under a reducing atmosphere; (2) under contact conditions, the calcium source, the solvent, and the first material obtained in step (1) are mixed, then a second additive is introduced, and a second material is obtained after drying; the second additive is selected from one or more of carboxymethyl cellulose, hydroxyethyl cellulose, microcrystalline cellulose, chitosan, sesbania gum, hydroxypropyl methyl cellulose, polyvinyl alcohol, silica sol, aluminum dihydrogen phosphate, and solutions thereof; (3) under microwave conditions, the second material obtained in step (2) is treated; the microwave treatment is performed in the presence of an inert gas, and the microwave heating treatment power is 10-1000 W / (g of the material); (4) the material obtained in step (3) is heat-treated under an oxygen-containing atmosphere to obtain the silicon carbide-doped calcium-based CO2 adsorbent.

2. The method of making a silicon carbide doped calcium-based CO2 adsorbent according to claim 1, characterized in that: The first additive in step (1) 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 making a silicon carbide doped calcium-based CO2 adsorbent of claim 1, characterized by: The first additive in step (1) is selected from one or more of aluminum nitrate, iron nitrate, magnesium nitrate, copper nitrate, silver nitrate, nickel nitrate, and zirconium nitrate.

4. The method of making a calcium-based CO2 adsorbent doped with silicon carbide according to claim 1, characterized in that: The organic solvent in step (1) is an alcohol solvent, and the alcohol solvent is one or more of ethanol, methanol, propanol, butanol, ethylene glycol, propylene glycol, glycerol, and butylene glycol.

5. The method of making a silicon carbide doped calcium-based CO2 adsorbent according to claim 4, characterized in that: The alcohol solvent is ethanol.

6. The method of making a calcium-based CO2 adsorbent doped with silicon carbide according to claim 1, characterized in that: The carbon source in step (1) is sucrose and / or a phenolic resin.

7. The method of making a calcium-based CO2 adsorbent doped with silicon carbide according to claim 1, characterized in that: The carbon source in step (1) is one or more of a water-soluble starch and dextrin.

8. The method of making a calcium-based CO2 adsorbent doped with silicon carbide according to claim 1, characterized in that: The dry basis content of the first additive is 0.01wt%-10.0wt% based on the mass of the silicon source, and the mass ratio of the carbon source to the silicon source is 0.3:1-10:

1.

9. The method of making a calcium-based CO2 adsorbent doped with silicon carbide according to claim 1, characterized in that: In step (1), the pH value of the material after the carbon source and the first additive solution are mixed is adjusted to 1-10 before the silicon source is introduced, and the pH value is adjusted by adding an acid or ammonia water; the acid is one or more of nitric acid, hydrochloric acid, phosphoric acid, oxalic acid, and citric acid.

10. The method of making a calcium-based CO2 adsorbent doped with silicon carbide according to claim 1, characterized in that: The drying temperature in step (1) is 100-150°C, and the calcination temperature in step (1) is 350-900°C.

11. The method of making a calcium-based CO2 adsorbent doped with silicon carbide according to claim 1, characterized in that: The reducing atmosphere is any one of a reducing gas, a mixture of a reducing gas and an inert atmosphere; the reducing gas is one or more of hydrogen, carbon monoxide, methane, and C2-C4 gas; and in the mixture, the volume content of the reducing gas is 0.5-100%.

12. The method of making a silicon carbide doped calcium-based CO2 adsorbent according to claim 11, characterized in that: The reducing gas is hydrogen and / or methane.

13. The method of making a calcium-based CO2 adsorbent doped with silicon carbide according to claim 1, characterized in that: The calcium source in step (2) is one or more of calcium oxide, a calcium hydroxide, and a calcium salt.

14. The method of making a silicon carbide doped calcium-based CO2 adsorbent according to claim 1, characterized by: The calcium source in step (2) is one or more of calcium oxalate, calcium gluconate, calcium hydroxide, calcium oxide, calcium carbonate, calcium acetate, calcium propionate, calcium acetylacetonate, calcium lactate, calcium formate, calcium citrate, and calcium nitrate.

15. The method of making a silicon carbide doped calcium-based CO2 adsorbent according to claim 1, characterized by: The calcium source in step (2) is one or more of calcium oxalate, calcium oxide, and calcium nitrate.

16. The method of making a silicon carbide doped calcium-based CO2 adsorbent according to claim 1, characterized by: The solvent in step (2) is water and / or an organic solvent; the organic solvent is an alcohol solvent selected from one or more of ethanol, methanol, propanol, butanol, ethylene glycol, propylene glycol, glycerol, and butylene glycol; when the solvent is a mixture of water and an organic solvent, the concentration of the organic solvent is 1wt%-80wt%.

17. The method of making a silicon carbide doped calcium-based CO2 adsorbent according to claim 16, characterized by: The alcohol solvent is ethanol.

18. The method of making a silicon carbide doped calcium-based CO2 adsorbent according to claim 1, characterized by: The second additive in step (2) is selected from one or more of carboxymethyl cellulose, sesbania powder, polyvinyl alcohol, and silica sol and solutions thereof.

19. The method of making a calcium-based CO2 adsorbent doped with silicon carbide according to claim 1, characterized in that: In step (2), the mass ratio of the solvent to the calcium source is 0.2:1-20:1, the weight ratio of the first material to the calcium source is 0.01:1-2:1, and the dry basis content of the second additive is 0.5wt%-10wt%, based on the mass of the calcium source.

20. The method of making a silicon carbide doped calcium-based CO2 adsorbent according to claim 1, characterized by: The drying temperature in step (2) is 100-150℃.

21. The method of making a calcium-based CO2 adsorbent doped with silicon carbide according to claim 1, characterized in that: After drying in step (2), a calcination treatment is performed, and the calcination temperature is 350-900℃.

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

23. The method of making a silicon carbide doped calcium-based CO2 adsorbent according to claim 1, characterized in that: The heat treatment temperature in step (4) is 500-1300℃.

24. The method of making a silicon carbide doped calcium-based CO2 adsorbent according to claim 1, characterized in that: The heat treatment temperature in step (4) is 500-800℃. 25.A silicon carbide-doped calcium-based CO2 adsorbent obtained by the preparation method of any one of claims 1-24.