A monolithic co2 adsorbent and its preparation method and application

Abstract

The application discloses a monolithic CO2 adsorbent and a preparation method and application thereof. The preparation method comprises the following steps: (1) mixing a carbon precursor and an auxiliary I solution under a mixing condition, introducing a silicon precursor, adjusting the pH value of a reaction system, and obtaining material I through drying and calcination treatment; (2) uniformly mixing a calcium-containing compound, the material I and a solvent, then introducing an auxiliary II to obtain a slurry; (3) adding polyurethane foam into the slurry obtained in the step (2) to perform impregnation treatment, and further performing heat treatment under a microwave condition to obtain the monolithic CO2 adsorbent. The application further provides the monolithic CO2 adsorbent obtained by using the preparation method. The monolithic CO2 adsorbent has the advantages of low medium pressure, adjustable porosity, high adsorption capacity, high sintering resistance, high strength, microwave heating, and long-term cyclic use.

Description

TECHNICAL FIELD

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

[0002] The target of carbon neutralization requires capturing and storing carbon dioxide gas in flue gas or tail gas of a coal-fired power plant or other industrial processes, and directly adsorbing CO2 in flue gas or tail gas using a high-temperature solid CO2 adsorbent, which has an operating temperature close to the temperature of flue gas or tail gas, is convenient for design and operation, does not require a high-temperature gas cooling process, and saves costs. Calcium-based CO2 adsorbents, as a high-temperature solid adsorbent with fast adsorption rate and high theoretical capacity, have always attracted much attention.

[0003] The monolithic adsorbent has uniform airflow distribution, low bed pressure drop, fast heat transfer speed, small radial and axial temperature gradient, and is not easy to be blocked by external dust, has high internal surface utilization rate, is suitable for high airspeed reaction, and is simple to install and can be installed horizontally or vertically. Therefore, the monolithic calcium-based CO2 adsorbent has great advantages in application to CO2 capture in flue gas or tail gas, but it faces a relatively complex process environment, and the porosity and active component content of the monolithic adsorbent need to be adjustable within a large range. At the same time, researchers often use the method of doping high-Taman temperature inert components to solve the problems of easy sintering and fusion, pore collapse, and rapid reduction of adsorption capacity of calcium-based CO2 adsorbents, but the traditional high-Taman temperature inert components have limited effect on improving the strength of the adsorbent, and it is difficult to meet the mechanical strength requirements when applied to the monolithic adsorbent. The coating preparation method can solve the problem of monolithic mechanical strength, but there is also the problem of loose and easy-to-fall coating.

[0004] CN102500310A discloses a high-temperature and high-activity calcium-based CO2 adsorbent prepared by generating Al(OH)3 wrapped on the surface of calcium citrate particles through a sol-gel method, and then aging, washing, drying, and calcining. CN102784630A discloses a preparation method of a calcium-based CO2 adsorbent, which dries a mixed solution containing calcium precursors and inert carrier precursors by using a spray dryer, and calcines to obtain the adsorbent. However, the above-mentioned patents have not proposed a preparation method of the monolithic adsorbent, and the unique advantages of the monolithic adsorbent cannot be brought into play. SUMMARY

[0005] In view of the deficiencies in the prior art, the present application aims to provide a silicon carbide-doped monolithic CO2 adsorbent and a preparation method thereof. The adsorbent has low pressure drop, adjustable porosity, high adsorption capacity, sintering resistance, high strength, can be heated by microwaves, and can be used for long-term cyclic use.

[0006] The application provides a preparation method of a monolithic CO2 adsorbent, comprising the following steps:

[0007] (1) mixing a carbon precursor and an auxiliary I solution under mixing conditions, introducing a silicon precursor, adjusting the pH value of the reaction system, and obtaining material I after drying and calcination;

[0008] (2) mixing a calcium-containing compound, the material I and a solvent under mixing conditions, and then introducing an auxiliary II to obtain a slurry;

[0009] (3) adding polyurethane foam into the slurry obtained in step (2) for impregnation treatment, and further performing heat treatment under microwave conditions to obtain the monolithic CO2 adsorbent.

[0010] In some specific embodiments, in the preparation method of the monolithic CO2 adsorbent, the carbon precursor in step (1) can be one or more of monosaccharides, disaccharides, water-soluble polysaccharides, phenolic aldehyde resins, water-soluble starches, dextrins, glycerol, furfural, furfuryl alcohol, preferably one or more of sucrose, water-soluble starches and phenolic aldehyde resins.

[0011] In some specific embodiments, in the preparation method of the monolithic CO2 adsorbent, the auxiliary I solution in step (1) comprises component A and water, wherein component A is one or more of nitrate, carbonate, phosphate, organic acid salt and 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; component A 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, zirconium acetate, and the like, and is more preferably one or more of aluminum nitrate, iron nitrate, magnesium nitrate, copper nitrate, silver nitrate, nickel nitrate and zirconium nitrate; the mass concentration of component A is 0.1wt%-15wt% based on the mass of the auxiliary I solution.

[0012] In some specific embodiments, in the preparation method of the monolithic CO2 adsorbent, the auxiliary I solution in step (1) comprises component B, which can be one or more of silicone oil, hexamethylenetetramine, formamide, N,N-dimethylformamide and polyethylene glycol (molecular weight: 200-20000). The auxiliary I solution further preferably comprises an organic solvent, which is preferably an alcohol solvent, and specifically can be one or more of ethanol, methanol, propanol, butanol, ethylene glycol, propylene glycol, glycerol and butylene glycol, and is further preferably ethanol. The concentration of the organic solvent is 1wt%-80wt% based on the mass of the auxiliary I solution.

[0013] In some embodiments, the preparation method of the monolithic CO2 adsorbent, the pH value in step (1) is controlled to be 1-12, preferably 1-10; the pH value of the material can be adjusted by adding acid or ammonia water, and the acid can be one or more of nitric acid, hydrochloric acid, phosphoric acid, oxalic acid, and citric acid.

[0014] In some embodiments, the preparation method of the monolithic CO2 adsorbent, the silicon precursor in step (1) can be one or more of soluble silicate, alkoxysilane, and silicon tetrachloride; the soluble silicate can be at least one of sodium silicate, lithium silicate, potassium silicate, and ammonium silicate; the alkoxysilane can be at least one 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.

[0015] In some embodiments, the preparation method of the monolithic CO2 adsorbent, the mass ratio of the carbon precursor to the silicon precursor is 0.3:1-10:1, the dry basis content of component A is 0.01wt%-10.0wt%, and the dry basis content of component B is preferably 1wt%-50wt%.

[0016] In some embodiments, the preparation method of the monolithic CO2 adsorbent, the drying temperature in step (1) is 100-150°C.

[0017] In some embodiments, the preparation method of the monolithic CO2 adsorbent, the calcination temperature in step (1) is 350-900°C, and the calcination time is 0.2-10 hours; the calcination in step (1) is carried out under an inert atmosphere and / or a reducing atmosphere, and is preferably carried out 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, a mixture of a reducing gas and an inert gas; the reducing gas is one or more of hydrogen, carbon monoxide, methane, and C2-C4 gas, and is preferably hydrogen and / or methane; in the mixture, the volume content of the reducing gas is 0.5%-99.5%.

[0018] In some embodiments, the preparation method of the monolithic CO2 adsorbent, the solid-liquid separation is preferably carried out before drying in step (1), and the separated solid material is dried.

[0019] In some embodiments, the calcium-containing compound in step (2) is one or more of calcium oxide, calcium hydroxide, and calcium salts, and the calcium-containing compound can be 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 is further preferably one or more of calcium oxalate, calcium oxide, and calcium nitrate.

[0020] In some embodiments, the solvent in step (2) is water and / or an organic solvent, and the organic solvent is an alcohol solvent, which can be one or more of ethanol, methanol, propanol, butanol, ethylene glycol, propylene glycol, glycerol, and butylene glycol, and is further preferably ethanol, and when the solvent is a mixture of water and an organic solvent, the concentration of the organic solvent is 1wt% to 80wt%.

[0021] In some embodiments, the auxiliary II 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.

[0022] In some embodiments, the mass ratio of the solvent to the calcium-containing compound in step (2) is 2:1 to 20:1, and the weight ratio of the material I to the calcium-containing compound is 0.01:1 to 2:1, and the dry content of the auxiliary II is 0.5wt% to 10wt%.

[0023] In some embodiments, the polyurethane foam in step (3) is a soft polyurethane foam having interconnected pores with a pore size of 5 to 200 ppi (pores per inch).

[0024] In some embodiments, the preparation method of the monolithic CO2 adsorbent, the polyurethane foam is preferably modified by treating the polyurethane foam in an acid solution or a base solution, followed by washing to obtain. The acid can be one or more of hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, oxalic acid, citric acid, and the mass concentration of the acid solution is 1wt%-20wt%; the base can be one or more of sodium hydroxide, potassium hydroxide, lithium hydroxide, and the mass concentration of the base solution is 1wt%-20wt%, and the treatment time is 1-10 hours. The washing is preferably performed under ultrasonic conditions.

[0025] In some embodiments, the preparation method of the monolithic CO2 adsorbent, the impregnation treatment in step (3) is to immerse the polyurethane foam into the slurry obtained in step (2), roll and squeeze the excess slurry after taking out, and then place in a vacuum drying machine at 60-150°C for 5-35min to take out, and preferably repeat the above process for several times, such as 3-10 times.

[0026] In some embodiments, the preparation method of the monolithic CO2 adsorbent, after the impregnation treatment in step (3), the material can be optionally calcined, the calcination temperature is 350-900°C, the calcination time is 1-10 hours, and 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.

[0027] In some embodiments, the preparation method of the monolithic CO2 adsorbent, the microwave power for the heat treatment in step (3) is 10-1000W / (g of material), preferably 100-500W / (g of material); the treatment time is 0.1-10 hours, preferably 0.1-1 hour; and the heat treatment is preferably performed in the presence of an inert gas, the inert gas is one or more of helium, neon, argon, krypton, and xenon.

[0028] In some embodiments, the preparation method of the monolithic CO2 adsorbent, the preparation method of the monolithic CO2 adsorbent further comprises step (4), and the step (4) is to heat treat the material obtained in step (3) in an oxygen-containing atmosphere. The oxygen-containing atmosphere can be any one of air, oxygen, and a mixture of oxygen and an inert atmosphere, in the mixture, the volume content of oxygen is 5%-99.99%; 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 heat treatment temperature is 500-1300°C, preferably 500-800°C, and the heat treatment time is 0.5-8 hours.

[0029] The second aspect of the present application provides a monolithic CO2 adsorbent obtained by the preparation method provided above.

[0030] The application also provides the use of the monolithic CO2 adsorbent described above and / or obtained by the preparation method described above in adsorbing CO2.

[0031] Compared with the prior art, the monolithic CO2 adsorbent and the preparation method thereof provided by the present application have the following advantages:

[0032] 1. The monolithic CO2 adsorbent provided by the present application has uniform pores, and the shape and porosity thereof can be controlled by selecting polyurethane foams with different shapes and pore sizes, and the permeability is good, which is conducive to reducing the bed pressure drop and the probability of channeling, and is more suitable for capturing CO2 in flue gas or tail gas with high dust and high air speed. At the same time, the adsorbent has a three-dimensional network continuous structure that penetrates each other, which is conducive to transferring reaction heat.

[0033] 2. In the preparation method of the monolithic CO2 adsorbent provided by the present application, silicon carbide is introduced in situ by a sol-gel method. Silicon carbide has excellent mechanical strength, thermal stability and chemical inertness, and effectively prevents CaO sintering while providing sufficient strength to the monolithic adsorbent, thereby avoiding the pulverization of the adsorbent and the increase of the pressure drop after multiple cycles, and ensuring long-term cyclic use. The support framework formed by the sol-gel method can regulate the surface morphology and pore structure of the adsorbent to some extent, and ensure the structure and adsorption stability of the adsorbent. At the same time, the three-dimensional network structure of silicon carbide can make microwaves continuously dissipate in the structure, thereby making the adsorbent have better microwave absorption properties.

[0034] 3. In the preparation method of the monolithic CO2 adsorbent provided by the present application, the use of microwaves can solve the contradiction between the high temperature of silicon carbide formation and the easy sintering of CaO active particles. In a microwave field, the dielectric properties of carbon, metal particles formed by component B, silicon carbide and calcium oxide are quite different. Compared with calcium oxide, the former three have a large heating rate, and the metal particles can even produce Joule heating effect and even cause microwave discharge phenomenon. This intensified microwave hot spot effect and selective heating effect can promote the formation of silicon carbide and the formation of the support framework while preventing the sintering of CaO active particles. At the same time, the introduction of part of the metals in component B can also reduce the synthesis difficulty of silicon carbide or form inert components with high Tamman temperature, further alleviating and preventing the sintering of CaO active particles. DETAILED DESCRIPTION

[0035] The present application will be further described in details by specific examples, but the scope of the present application is not limited by the examples. In the present application, the molecular weight of the polyvinyl alcohol is the viscosity average molecular weight.

[0036] The specific embodiments of the present application will be described in details below, but it should be noted that the scope of the present application is not limited by these specific embodiments, but is determined by the claims attached herewith.

[0037] All publications, patent applications, patents and other references mentioned in this specification are herein incorporated by reference. Unless otherwise defined, all technical and scientific terms used in this specification are intended to have the meanings commonly attributed to them by those of ordinary skill in the art. In case of conflict between the definitions in this specification and those in the incorporated references, the definitions in this specification shall control.

[0038] When the specification states that a material, substance, composition, process, step, apparatus or component etc. is "known to those of ordinary skill in the art", it is intended that the disclosure be interpreted to cover those items which are currently known as well as those which become known in the future.

[0039] Unless specifically stated otherwise, throughout this specification and the claims, the terms "comprise", "comprising", "include", "including", "contain", "containing" or the like mean "including but not limited to", and are not intended to (and do not) exclude other moieties, constituents, elements or steps. Throughout this document, all numerical values should be interpreted as being modified in all instances by the term "about", unless otherwise specifically indicated.

[0040] Unless specifically stated otherwise, throughout this specification and the claims, all percentages, parts, ratios, etc. are by weight and all pressures are at or near atmospheric pressure.

[0041] In the context of this document, any two or more embodiments of the application can be combined in any manner to form further embodiments of the application, which are also within the scope of the present application.

[0042] In the following examples and comparative examples, the specific conditions not otherwise specified were carried out under the conventional conditions or the conditions recommended by the manufacturer. The reagents or instruments not otherwise specified were all conventional products which can be obtained by the commercial route.

[0043] Example 1

[0044] Aluminum nitrate, formamide were added into deionized water containing 40% ethanol, stirred rapidly, then sucrose was added, followed by slow addition of tetraethyl orthosilicate, and the pH was adjusted to 8-9 with ammonia water. Among them, the content of aluminum nitrate was 5% and the content of formamide was 20% based on the mass of tetraethyl orthosilicate, and the mass ratio of sucrose to tetraethyl orthosilicate was 2:1. 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 material I.

[0045] Calcium nitrate was slowly added to deionized water, stirred rapidly, then material I was slowly added, and then sesbania powder and silica sol were slowly added to obtain a slurry. Among them, the mass ratio of solvent to calcium nitrate was 10:1 based on the mass of calcium nitrate, the weight ratio of material I to calcium nitrate was 0.2:1, the dry basis content of sesbania powder was 5%, and the dry basis content of silica sol was 0.5%.

[0046] A soft polyurethane foam with a pore size of 100 ppi (pores per inch) and interconnected pores was selected as a template. The polyurethane foam was soaked in a 20% NaOH solution for 5 hours, then washed with deionized water. The above polyurethane foam was immersed in the slurry, and after taking it out, the excess slurry was rolled and squeezed off, and placed in a vacuum drying machine at 120°C for drying. After 35 minutes, it was taken out, and the above process was repeated 5 times. Then constant temperature was maintained 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 500 W / (g of material) for 1 hour in an argon atmosphere. The above material was constant temperature maintained at 500°C for 4 hours in an air atmosphere to obtain a monolithic CO2 adsorbent.

[0047] Example 2

[0048] Nickel nitrate, zirconium nitrate, N,N-dimethylformamide were added into deionized water containing 1% methanol, stirred rapidly, then glucose was added, followed by slow addition of sodium silicate, and the pH was adjusted to 1-2 with hydrochloric acid. Among them, the content of nickel nitrate was 0.5% and the content of zirconium nitrate was 8% based on the mass of sodium silicate, the content of N,N-dimethylformamide was 50%, and the mass ratio of glucose to sodium silicate was 10:1. Drying was carried out at 150°C, and then constant temperature was maintained at 700°C for 7 hours in a hydrogen atmosphere to obtain material I.

[0049] Calcium oxide was slowly added to deionized water containing 5% ethanol, stirred rapidly, then material I was slowly added, and then carboxymethyl cellulose and silica sol were slowly added to obtain a slurry. Among them, the mass ratio of solvent to calcium oxide was 20:1 based on the mass of calcium oxide, the weight ratio of material I to calcium oxide was 2:1, the dry basis content of carboxymethyl cellulose was 5%, and the dry basis content of silica sol was 1%.

[0050] A soft polyurethane foam with interconnected pores having a pore size of 150 ppi (pores per inch) was chosen as a template. The polyurethane foam was soaked in a 20 wt% oxalic acid solution for 7 hours, and then washed with deionized water. The polyurethane foam was immersed in the slurry, and after being taken out, the excess slurry was squeezed out by rolling, and then placed in a vacuum drying machine for drying at 120°C. After 35 minutes, the polyurethane foam was taken out, and the above process was repeated 6 times. Then, the polyurethane foam was kept at a constant temperature of 600°C for 1 hour in a nitrogen atmosphere. The material was put into a microwave calcination furnace, and treated at a power of 400 W / (g of material) for 1 hour in an argon atmosphere. The material was kept at a constant temperature of 400°C for 8 hours in an air atmosphere, and a monolithic CO2 adsorbent was obtained.

[0051] Example 3

[0052] Zirconium nitrate was added to deionized water containing 80% methanol, and stirred rapidly. Phenolic resin was added, and then tetramethyl orthosilicate was added slowly. The pH was adjusted to 5-6 using phosphoric acid. The content of zirconium nitrate was 4% based on the mass of tetramethyl orthosilicate. The mass ratio of phenolic resin to tetramethyl orthosilicate was 3:1. Drying was performed at 150°C, and then the material was kept at a constant temperature of 800°C for 3 hours in a methane atmosphere. Material I was obtained.

[0053] Calcium oxalate was slowly added to deionized water containing 1% glycerol, and then stirred rapidly. Material I was slowly added, and then polyvinyl alcohol (average molecular weight of 22000) and aluminum dihydrogen phosphate were slowly added to obtain a slurry. The mass ratio of solvent to calcium oxalate was 5:1 based on the mass of calcium oxalate. The weight ratio of material I to calcium oxalate was 0.6:1. The dry basis content of polyvinyl alcohol (average molecular weight of 22000) was 0.5%. The dry basis content of aluminum dihydrogen phosphate was 0.5%.

[0054] A soft polyurethane foam with interconnected pores having a pore size of 200 ppi (pores per inch) was chosen as a template. The polyurethane foam was soaked in a 1% nitric acid solution for 10 hours, and then washed with deionized water. The polyurethane foam was immersed in the slurry, and after being taken out, the excess slurry was squeezed out by rolling, and then placed in a vacuum drying machine for drying at 140°C. After 10 minutes, the polyurethane foam was taken out, and the above process was repeated 7 times. Then, the polyurethane foam was kept at a constant temperature of 650°C for 4 hours in a nitrogen atmosphere. The material was put into a microwave calcination furnace, and treated at a power of 1000 W / (g of material) for 0.5 hour in an argon atmosphere. The material was kept at a constant temperature of 650°C for 2 hours in a nitrogen atmosphere containing 50% oxygen, and a monolithic CO2 adsorbent was obtained.

[0055] Example 4

[0056] Magnesium nitrate, polyethylene glycol (molecular weight 200) were added into deionized water, stirred rapidly, then added dextrin, slowly added potassium silicate, and adjusted pH to 2-3 with nitric acid. Among them, based on the mass of potassium silicate, the content of magnesium nitrate was 1%, the content of polyethylene glycol (molecular weight 200) was 10%, and the mass ratio of dextrin to potassium silicate was 1.5:1. Solid-liquid separation was carried out, dried at 120°C, then kept at 900°C for 2 hours in an ethane atmosphere to obtain material I.

[0057] Calcium lactate was slowly added into deionized water containing 80% methanol, stirred rapidly, then slowly added material I, then slowly added microcrystalline cellulose and aluminum dihydrogen phosphate to obtain a slurry. Among them, based on the mass of calcium lactate, the mass ratio of solvent to calcium lactate was 2:1, the weight ratio of material I to calcium lactate was 0.1:1, the dry basis content of microcrystalline cellulose was 9%, and the dry basis content of aluminum dihydrogen phosphate was 1%.

[0058] A soft polyurethane foam with a pore size of 20 ppi (pores per inch) and interconnected pores was selected as a template. The polyurethane foam was soaked in a 10% hydrochloric acid solution for 1 hour, then washed with deionized water. The above polyurethane foam was immersed in the slurry, and after taking it out, the excess slurry was rolled and squeezed off, and placed in a vacuum drying machine at 60°C for drying. After 35 minutes, it was taken out, and the above process was repeated 10 times. Then, it was kept at 800°C for 0.5 hours in a nitrogen atmosphere. The above material was sent into a microwave calcination furnace, treated at a power of 100 W / (g material) for 1.5 hours in an argon atmosphere. The above material was kept at 800°C for 1 hour in an oxygen atmosphere to obtain a monolithic CO2 adsorbent.

[0059] Comparative Example 1

[0060] Formamide was added into deionized water containing 40% ethanol, stirred rapidly, then added sucrose, slowly added tetraethyl orthosilicate, and adjusted pH to 8-9 with ammonia water. Among them, based on the mass of tetraethyl orthosilicate, the content of formamide was 20%, and the mass ratio of sucrose to tetraethyl orthosilicate was 2:1. Dried at 120°C, then kept at 600°C for 2 hours in a hydrogen atmosphere to obtain material I.

[0061] Calcium nitrate was slowly added into deionized water, stirred rapidly, then slowly added material I, then slowly added sesbania powder and silica sol to obtain a slurry. Among them, based on the mass of calcium nitrate, the mass ratio of solvent to calcium nitrate was 10:1, the weight ratio of material I to calcium nitrate was 0.2:1, the dry basis content of sesbania powder was 5%, and the dry basis content of silica sol was 0.5%.

[0062] A soft polyurethane foam with interconnected pores of 100 ppi (pores per inch) was chosen as a template. The polyurethane foam was soaked in 20% NaOH solution for 5 hours, and then washed with deionized water. The polyurethane foam was immersed in the slurry, and after being taken out, the excess slurry was squeezed out by rolling, and then placed in a vacuum drying machine at 120°C for drying. After 35 minutes, the above process was repeated 5 times. Then, the above material was placed in a microwave calcination furnace under an argon atmosphere at 350°C for 10 hours. The above material was placed in a microwave calcination furnace under an argon atmosphere at a power of 500 W / (g of material) for 1 hour. The above material was placed in an air atmosphere at 500°C for 4 hours to obtain a monolithic CO2 adsorbent.

[0063] Comparative Example 2

[0064] SiC micro powder, alumina, yttrium oxide, and carbon black were mixed and finely ground to obtain material I. Among them, based on the mass of SiC micro powder, the content of alumina was 5%, the content of yttrium oxide was 2%, and the content of carbon black was 10%.

[0065] Calcium nitrate was slowly added to deionized water, and then quickly stirred. Then, material I was slowly added, and then sesbania powder and silica sol were slowly added to obtain a slurry. Among them, based on the mass of calcium nitrate, the mass ratio of solvent to calcium nitrate was 5:1, the weight ratio of material I to calcium nitrate was 0.1:1, the dry basis content of sesbania powder was 5%, and the dry basis content of silica sol was 0.5%.

[0066] A soft polyurethane foam with interconnected pores of 100 ppi (pores per inch) was chosen as a template. The polyurethane foam was soaked in 20% NaOH solution for 5 hours, and then washed with deionized water. The polyurethane foam was immersed in the slurry, and after being taken out, the excess slurry was squeezed out by rolling, and then placed in a vacuum drying machine at 120°C for drying. After 35 minutes, the above process was repeated 5 times. Then, the above material was placed in a microwave calcination furnace under an argon atmosphere at 350°C for 10 hours. The above material was placed in a microwave calcination furnace under an argon atmosphere at a power of 500 W / (g of material) for 3 hours. The above material was placed in an air atmosphere at 500°C for 4 hours to obtain a monolithic CO2 adsorbent.

[0067] Comparative Example 3

[0068] Aluminum nitrate and formamide were added to deionized water containing 40% ethanol, and then quickly stirred. Then, sucrose was added, and then tetraethyl orthosilicate was slowly added, and the pH was adjusted to 8-9 with ammonia water. Among them, based on the mass of tetraethyl orthosilicate, the content of aluminum nitrate was 5%, the content of formamide was 20%, and the mass ratio of sucrose to tetraethyl orthosilicate was 2:1. Drying was performed at 120°C, and then the material I was obtained by placing it in a hydrogen atmosphere at 600°C for 2 hours.

[0069] The calcium nitrate was slowly added into deionized water, stirred rapidly, then material I was slowly added, then the pearl millet powder and silica sol were slowly added to obtain the slurry. The mass ratio of solvent to calcium nitrate was 10:1, the weight ratio of material I to calcium nitrate was 0.2:1, the dry basis content of pearl millet powder was 5%, and the dry basis content of silica sol was 0.5% based on the mass of calcium nitrate.

[0070] The soft polyurethane foam with a pore size of 100 ppi (pores per inch) and interconnected pores was selected as a template. The polyurethane foam was soaked in a 20% NaOH solution for 5 hours, and then washed with deionized water. The polyurethane foam was immersed in the slurry, and after being taken out, the excess slurry was rolled and squeezed off, and then placed in a vacuum drying machine for drying at 120°C. After 35 minutes, the polyurethane foam was taken out, and the above process was repeated 5 times. Then, the polyurethane foam was kept at a constant temperature of 1700°C for 7 hours in an argon atmosphere. The above material was kept at a constant temperature of 500°C for 4 hours in an air atmosphere to obtain the monolithic CO2 adsorbent.

[0071] Adsorbent performance evaluation:

[0072] The CO2 adsorption capacity of the monolithic CO2 adsorbent prepared in Examples 1-4 and Comparative Examples 1-3 was determined by a thermogravimetric analyzer (TGA). The determination conditions were as follows: the adsorption temperature was 650°C, the desorption temperature was 800°C, the number of cycles was 100, and the average value was taken. The results are shown in Table 1.

[0073] Table 1 CO2 adsorption capacity of adsorbent

[0074] Catalyst Adsorption capacity / g CO2 / g 吸附剂 ]] Example 1 0.43 Example 2 0.37 Example 3 0.40 Example 4 0.42 Comparative Example 1 0.33 Comparative Example 2 0.13 Comparative Example 3 0.03

Claims

1. A method for preparing a monolithic CO2 adsorbent, comprising the following steps: (1) under mixing conditions, mixing the carbon precursor with the solution of aid I, introducing the silicon precursor, adjusting the pH value of the reaction system, and after drying and calcination, obtaining material I; the solution of aid I includes component A and water, wherein component A 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, neodymium; the carbon precursor is one or more of monosaccharide, disaccharide, water-soluble polysaccharide, phenolic resin, glycerol, furfural, furfuryl alcohol; the auxiliary I solution comprises component B, and the component B is one or more of silicone oil, hexamethylenetetramine, formamide, N, N-dimethylformamide, polyethylene glycol; the silicon precursor is one or more of soluble silicate, alkoxysilane, silicon tetrachloride; the calcination is performed under a reducing atmosphere; (2) under mixing conditions, the calcium-containing compound, the material I and the solvent are uniformly mixed, then the auxiliary II is introduced to obtain a slurry; the auxiliary II 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) the polyurethane foam is added to the slurry obtained in step (2) for impregnation treatment, and further heat treatment is performed under microwave conditions; the heat treatment is performed in the presence of an inert gas, and the microwave power of the heat treatment is 100-1000 W / (g of the material); the polyurethane foam is a soft polyurethane foam with a pore size of 5-200 ppi and interconnected pores; (4) the material obtained in step (3) is subjected to heat treatment in an oxygen-containing atmosphere to obtain the monolithic CO2 adsorbent.

2. The method of making a monolithic CO2 adsorbent of claim 1, wherein, The carbon precursor in step (1) is one or more of water-soluble starch and dextrin.

3. The method of making a monolithic CO2 adsorbent of claim 1, wherein, The carbon precursor in step (1) is one or more of sucrose, water-soluble starch and phenolic resin.

4. The method of making a monolithic CO2 adsorbent of claim 1, wherein, The component A 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.

5. The method of making a monolithic CO2 adsorbent of claim 1, wherein, The component A is one or more of aluminum nitrate, iron nitrate, magnesium nitrate, copper nitrate, silver nitrate, nickel nitrate and zirconium nitrate.

6. The method of making a monolithic CO2 adsorbent of claim 1, wherein, The auxiliary I solution comprises an organic solvent, and the organic solvent is an alcohol solvent.

7. The method of making a monolithic CO2 adsorbent of claim 6, wherein, The alcohol solvent is one or more of ethanol, methanol, propanol, butanol, ethylene glycol, propylene glycol, glycerol and butanediol.

8. The method of making a monolithic CO2 adsorbent of claim 7, wherein, The alcohol solvent is ethanol.

9. The method of making a monolithic CO2 adsorbent of claim 1, wherein, In step (1), the pH value of the system is controlled to be 1-12; the pH value of the material is adjusted by adding acid or ammonia water, and the acid is one or more of nitric acid, hydrochloric acid, phosphoric acid, oxalic acid and citric acid.

10. The method of making a monolithic CO2 adsorbent of claim 9, wherein, In step (1), the pH value of the system is controlled to be 1-10.

11. The method of making a monolithic CO2 adsorbent of claim 1, wherein, The soluble silicate is at least one of sodium silicate, lithium silicate, potassium silicate and ammonium silicate; the alkoxysilane is at least one of methyl orthosilicate, ethyl orthosilicate, propyl orthosilicate, isopropyl orthosilicate, dimethyldiethoxysilane, methyltriethoxysilane, methyltrimethoxysilane, vinyltriethoxysilane and n-octyltriethoxysilane.

12. The method of making a monolithic CO2 adsorbent of claim 1, wherein, The silicon precursor is one or more of sodium silicate, ethyl orthosilicate and dimethyldiethoxysilane.

13. The method of making a monolithic CO2 adsorbent of claim 1, wherein, The mass ratio of the carbon precursor to the silicon precursor is 0.3:1-10:1 based on the mass of the silicon precursor; the dry basis content of component A is 1wt%-50wt%; and the dry basis content of component B is 0.01wt%-10.0wt%.

14. The method of making a monolithic CO2 adsorbent of claim 1, wherein, The drying temperature in step (1) is 100-150°C.

15. The method of making a monolithic CO2 adsorbent of claim 1, wherein, The calcination temperature in step (1) is 350-900°C, 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, wherein the volume content of the reducing gas in the mixed gas is 0.5-99.5%; the reducing gas is any one or more of hydrogen, carbon monoxide, methane and C2-C4 gas; and the inert atmosphere is nitrogen and / or an inert gas.

16. The method of making a monolithic CO2 adsorbent of claim 15, wherein, The reducing gas is hydrogen and / or methane.

17. The method of making a monolithic CO2 adsorbent of claim 1, wherein, The calcium-containing compound in step (2) is any one or more of calcium oxide, calcium hydroxide and calcium salt.

18. The method of making a monolithic CO2 adsorbent of claim 1 or 17, wherein, The calcium-containing compound in step (2) is any 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.

19. The method of making a monolithic CO2 adsorbent of claim 1 or 17, wherein, The calcium-containing compound in step (2) is any one or more of calcium oxalate, calcium oxide and calcium nitrate.

20. The method of making a monolithic CO2 adsorbent of claim 1, wherein, The solvent in step (2) is water and / or an organic solvent, and the organic solvent is an alcohol solvent; the alcohol solvent is selected from any one or more of ethanol, methanol, propanol, butanol, ethylene glycol, propylene glycol, glycerol and butylene glycol; and when the solvent is a mixed solvent of water and an organic solvent, the concentration of the organic solvent is 1wt%-80wt%.

21. The method of making a monolithic CO2 adsorbent of claim 20, wherein, The alcohol solvent is ethanol.

22. The method of making a monolithic CO2 adsorbent of claim 1, wherein, The auxiliary II in step (2) is selected from any one or more of carboxymethyl cellulose, sesbania powder, polyvinyl alcohol, silica sol and solutions thereof; and the molecular weight of the polyvinyl alcohol is 0.5-150,000.

23. The method of making a monolithic CO2 adsorbent of claim 1, wherein, In step (2), the mass ratio of the solvent to the calcium-containing compound is 2:1-20:1 based on the mass of the calcium-containing compound, the weight ratio of the material I to the calcium-containing compound is 0.01:1-2:1, and the dry basis content of the auxiliary II is 0.5wt%-10wt%.

24. The method of making a monolithic CO2 adsorbent of claim 1, wherein, The polyurethane foam is subjected to a modification treatment, the modification treatment being that the polyurethane foam is treated in an acid solution or an alkali solution and then washed to obtain; the acid is any one or more of hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, oxalic acid and citric acid, and the mass concentration of the acid solution is 1wt%-20wt%; the alkali is any one or more of sodium hydroxide, potassium hydroxide and lithium hydroxide, and the mass concentration of the alkali solution is 1wt%-20wt%; the treatment time is 1-10 hours; and the washing is washing with deionized water and is performed under ultrasonic conditions.

25. The method of making a monolithic CO2 adsorbent of claim 1, wherein, In step (3), the impregnation treatment is followed by a calcination treatment, the calcination temperature is 350-900°C, the calcination time is 1-10 hours, and the calcination is performed in the presence of an inert atmosphere, which is nitrogen and / or an inert gas.

26. The method of making a monolithic CO2 adsorbent of claim 1, wherein, In step (3), the microwave power for the heat treatment is 100-500W / (g of material); and the treatment time is 0.1-10 hours.

27. The method of making a monolithic CO2 adsorbent of claim 26, wherein, In step (3), the treatment time for the heat treatment is 0.1-1 hour.

28. The method of making a monolithic CO2 adsorbent of claim 1, wherein, The heat treatment temperature in step (4) is 500-1300°C, and the heat treatment time is 0.5-8 hours.

29. The method of making a monolithic CO2 adsorbent of claim 1, wherein, The heat treatment temperature in step (4) is 500-800°C.

30. A monolithic CO2 adsorbent obtained by the preparation method of any one of claims 1-29.

31. Use of the monolithic CO2 adsorbent of claim 30 for adsorbing CO2.