Preparation method of carbon dioxide solid adsorbent and carbon dioxide solid adsorbent

Abstract

The invention relates to a carbon dioxide solid adsorbent preparation method and a carbon dioxide solid adsorbent, and belongs to the technical field of carbon dioxide adsorption. The method comprises the following steps: preparing an alkali metal salt solution with the concentration of 0.2-0.6 mol / L by adopting metal salt, wherein the metal salt is selected from lithium nitrate and potassium acetate; adding 15-20 parts by mass of magnesium oxide powder into 100 parts by mass of alkali metal salt solution, and stirring to obtain a mixed solution; pre-dried biomass powder is added into the mixed solution to obtain biomass powder impregnation liquid, the biomass powder impregnation liquid is mixed and stirred, and 30-40 g of biomass powder is added into every 100 ml of the mixed solution; drying the biomass powder impregnation liquid to obtain a solid intermediate material, and pyrolyzing the solid intermediate material at 500-700 DEG C to obtain a solid adsorption material; and mixing the solid adsorption material, deionized water and an adhesive, and carrying out shaping treatment on the obtained mixture to obtain the carbon dioxide solid adsorbent.

Description

Technical Field

[0001] The present application relates to the technical field of carbon dioxide adsorption, and particularly to a preparation method of a solid carbon dioxide adsorbent and a solid carbon dioxide adsorbent. Background Art

[0002] Carbon dioxide adsorbents are a key link in the technology of carbon capture, utilization and storage (CCUS).

[0003] At present, carbon dioxide adsorbents are mainly divided into two categories: solid adsorbents and liquid adsorbents. Solid adsorbents include zeolites, molecular sieves, activated carbon, metal organic frameworks (MOFs), etc. These adsorbents have good stability, are easy to regenerate and have low corrosion to equipment, so they have been widely used. Among many solid carbon dioxide adsorbents, magnesium oxide is considered an ideal solid adsorption material because of its high adsorption capacity, low cost, low regeneration energy consumption and wide availability.

[0004] However, in the prior art, the adsorption amount of magnesium oxide solid adsorbent for carbon dioxide is small, and there is room for further improvement. Summary of the Invention

[0005] Embodiments of the present application provide a preparation method of a solid carbon dioxide adsorbent and a solid carbon dioxide adsorbent, so as to at least solve the problem that the adsorption amount of magnesium oxide solid adsorbent for carbon dioxide in the related art is small.

[0006] In a first aspect, embodiments of the present application provide a preparation method of a solid carbon dioxide adsorbent, and the method includes:

[0007] Prepare an alkali metal salt solution with a concentration of 0.2 - 0.6 mol / L using a metal salt, and the metal salt is selected from lithium nitrate and potassium acetate;

[0008] Add 15 - 20 parts by mass of magnesium oxide powder to 100 parts by mass of the alkali metal salt solution, and stir to obtain a mixed solution;

[0009] Add pre-dried biomass powder to the mixed solution to obtain a biomass powder impregnation solution, and mix and stir the biomass powder impregnation solution, wherein 30 - 40 g of the biomass powder is added to every 100 ml of the mixed solution;

[0010] Dry the biomass powder impregnation solution to obtain a solid intermediate material, and pyrolyze the solid intermediate material at 500 - 700 °C to obtain a solid adsorption material;

[0011] Mix the solid adsorbent material, deionized water, and binder, and shape the resulting mixture to obtain the carbon dioxide solid adsorbent.

[0012] In one example, preparing the alkali metal salt solution with a concentration of 0.2 - 0.6 mol / L using a metal salt includes:

[0013] Prepare a lithium nitrate solution and a potassium acetate solution with a concentration of 0.2 - 0.6 mol / L respectively using deionized water;

[0014] Mix the lithium nitrate solution and the potassium acetate solution in equal volumes to obtain the alkali metal salt solution;

[0015] In one example, the pre-dried biomass powder is prepared through the following steps:

[0016] Crush the biomass raw material with a crusher and sieve it using a 60 - 80 mesh sieve to obtain biomass powder; dry the biomass powder at 100 - 120 °C for 4 - 6 hours to obtain the pre-dried biomass powder.

[0017] In one example, drying the biomass powder impregnation solution to obtain a solid intermediate material includes:

[0018] Dry the biomass powder impregnation solution at 100 - 110 °C for at least 12 hours;

[0019] Crush the dried solid material and screen it through 60 and 80 mesh sieves, and use the 60 - 80 mesh sieve fraction as the solid intermediate material.

[0020] In one example, mixing and stirring the biomass powder impregnation solution includes:

[0021] Place the biomass powder impregnation solution in an ultrasonic device for ultrasonic oscillation and magnetic stirring for 60 - 90 minutes;

[0022] After ultrasonic oscillation, place the biomass powder impregnation solution in a constant temperature water bath with a water temperature of 50 - 60 °C for magnetic stirring and impregnation for at least 20 hours.

[0023] In one example, pyrolyzing the solid intermediate material at 500 - 700 °C to obtain a solid adsorbent material includes:

[0024] Use a tube furnace, with a target temperature of 550 - 650 °C, a nitrogen flow rate of 300 - 400 mL / min, a heating rate of 5 - 10 °C / min, and a constant temperature for 30 min.

[0025] In one example, the binder is selected from alumina and silica. Mixing the solid adsorbent material, deionized water, and the binder includes:

[0026] Mix in a ratio of the mass ratio of the solid adsorbent material, deionized water, and the binder of 15 - 20:6 - 10:1, and stir for 4 - 8 hours, then let it stand for at least 10 hours.

[0027] In one example, the mass ratio of the solid adsorbent material, deionized water, and the binder is 18:10:1.

[0028] In one example, before adding 15 - 20 parts by mass of magnesium oxide powder to 100 parts by mass of the alkali metal salt solution, the method further includes:

[0029] Calcine magnesium carbonate under the conditions of a target temperature of 500 - 700 °C and a heating rate of 5 °C / min. After reaching the target temperature, calcine for 2 - 3 hours, and then cool to obtain the magnesium oxide powder.

[0030] In a second aspect, the present application provides a carbon dioxide solid adsorbent, which is prepared by using the preparation method provided in the first aspect above.

[0031] Compared with the related art, the carbon dioxide solid adsorbent preparation method and the carbon dioxide solid adsorbent provided by the embodiments of the present application at least have the following technical effects:

[0032] The solid carbon dioxide adsorbent preparation method provided by the embodiments of the present application utilizes the biomass char obtained by low - temperature pyrolysis of biomass materials. The finally prepared solid adsorbent has a well - developed pore structure, a large specific surface area, and a strong alkaline metal loading capacity, effectively improving the carbon dioxide adsorption capacity of the adsorbent. In addition, biomass materials with wide sources and low prices are used, effectively reducing the production cost of the solid adsorbent material.

[0033] Details of one or more embodiments of the present application are set forth in the following drawings and description to make other features, objects, and advantages of the present application more comprehensible. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The drawings described herein are used to provide a further understanding of the present application and form a part of the present application. The illustrative embodiments and descriptions thereof are used to explain the present application and do not constitute an improper limitation of the present application. In the drawings:

[0035] Figure 1 is a flowchart of a carbon dioxide solid adsorbent preparation method shown according to an exemplary embodiment;

[0036] Figure 2It is a scanning electron microscope image of biomass semicoke shown according to an exemplary embodiment;

[0037] Figure 3 It is a scanning electron microscope image of the carbon dioxide solid adsorption material prepared according to Example 1;

[0038] Figure 4 It is a transmission electron microscope image of the carbon dioxide solid adsorption material prepared according to Example 1.

[0039] Figure 5 It is a scanning electron microscope image of the carbon dioxide solid adsorption material prepared according to Example 2;

[0040] Figure 6 It is a transmission electron microscope image of the carbon dioxide solid adsorption material prepared according to Example 2. Detailed implementation manners

[0041] In order to make the objectives, technical solutions and advantages of the present application clearer and more understandable, the present application will be described and explained below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application. Based on the embodiments provided in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present application.

[0042] Obviously, the accompanying drawings in the following description are only some examples or embodiments of the present application. For those of ordinary skill in the art, without creative efforts, the present application can also be applied to other similar scenarios based on these drawings. In addition, it can also be understood that although the efforts made in this development process may be complex and lengthy, for those of ordinary skill in the art related to the content disclosed in the present application, some designs, manufacturing or production changes based on the technical content disclosed in the present application are only conventional technical means and should not be understood as the content disclosed in the present application being insufficient.

[0043] Referring to "embodiment" in the present application means that the specific features, structures or characteristics described in combination with the embodiment can be included in at least one embodiment of the present application. The phrase appears in various positions in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those of ordinary skill in the art explicitly and implicitly understand that the embodiments described in the present application can be combined with other embodiments without conflict.

[0044] Unless otherwise defined, the technical terms or scientific terms involved in this application shall have the ordinary meanings understood by those with ordinary skills in the technical field to which this application belongs. The words such as "a", "an", "one kind", "the" and the like involved in this application do not indicate a limitation in quantity and may represent singular or plural. The terms "comprising", "including", "having" and any variations thereof involved in this application are intended to cover non-exclusive inclusion; for example, a process, method, system, product or device comprising a series of steps or modules (units) is not limited to the listed steps or units, but may further include unlisted steps or units, or may further include other steps or units inherent to these processes, methods, products or devices. The words such as "connected", "linked", "coupled" and the like involved in this application are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. The "plurality" involved in this application means two or more. "And / or" describes the association relationship of associated objects and indicates that three relationships may exist. For example, "A and / or B" may represent: A exists alone, A and B exist simultaneously, and B exists alone. The character " / " generally represents an "or" relationship between the associated objects before and after. The terms "first", "second", "third" and the like involved in this application are only used to distinguish similar objects and do not represent a specific order for the objects.

[0045] In a first aspect, an embodiment of the present application provides a method for preparing a carbon dioxide solid adsorbent. Figure 1 It is a flowchart of a method for preparing a carbon dioxide solid adsorbent shown according to an exemplary embodiment, as Figure 1 shown, the method includes:

[0046] Step S1: Prepare an alkali metal salt solution with a concentration of 0.2 - 0.6 mol / L using a metal salt, and the metal salt is selected from lithium nitrate and potassium acetate.

[0047] In one example, in step S1, a lithium nitrate solution and a potassium acetate solution with a concentration of 0.2 - 0.6 mol / L are respectively prepared using deionized water. Then, the lithium nitrate solution and the potassium acetate solution are mixed in equal volume to obtain an alkali metal salt solution. Lithium nitrate and potassium acetate are used to provide more basic sites for the subsequently prepared solid adsorbent material to optimize the adsorption performance of the adsorbent material.

[0048] Among them, the concentrations of the lithium nitrate solution and the potassium acetate solution are preferably 0.3 - 0.5 mol / L to ensure the uniformity of the dispersion of solid substances in the mixed solution and reduce agglomeration after the subsequent mixing of the alkali metal solution with other substances, thereby optimizing the mechanical properties and stability of the finally prepared carbon dioxide solid adsorbent.

[0049] Step S2: Add 15 - 20 parts by mass of magnesium oxide powder to 100 parts by mass of the alkali metal salt solution, and stir to obtain a mixed solution.

[0050] Among them, the magnesium oxide powder can be 16, 17, 18, or 19 parts by mass, without specific limitation. The dosage of magnesium oxide in step S2 is related to the surface morphology and carbon dioxide adsorption performance of the finally prepared adsorbent. By the specific ratio in step S2, surface agglomeration of the finally prepared reagent is avoided, ensuring the adsorption performance. In addition, the mass ratio of magnesium oxide to the alkali metal solution ensures that the prepared carbon dioxide adsorbent material has sufficient mechanical properties and does not affect the use of the adsorbent.

[0051] As an alternative, the magnesium oxide powder is prepared in the following way: Under the conditions of a target temperature of 500 - 700 °C (such as 550 °C, 600 °C, 650 °C) and a heating rate of 5 °C / min, calcine magnesium carbonate in a muffle furnace. After reaching the target temperature, calcine for 2 - 3 hours, and then cool to obtain the magnesium oxide powder. The method of obtaining magnesium oxide powder by calcination is used to ensure the purity of the prepared powder and avoid impurities affecting the adsorption effect of the final adsorbent.

[0052] Step S3: Add the pre - dried biomass powder to the mixed solution to obtain a biomass powder impregnation solution, and mix and stir the biomass powder impregnation solution.

[0053] Among them, 30 - 40 g of biomass powder is added to every 100 ml of the mixed solution. For example, the mass of biomass powder added to every 100 ml of the mixed solution can be selected as 32, 34, 35, 36, 38 g of biomass powder, or the intermediate value of any two values. The biomass powder is used to form biomass semi - coke in subsequent treatment. The biomass semi - coke has a porous structure, providing an attachment framework for magnesium oxide, alkali metals, etc., thereby increasing the specific surface area of the overall carbon dioxide solid adsorbent and increasing the basic sites on the adsorbent.

[0054] In step S3, by stirring the biomass powder impregnation solution, it is ensured that different solid components are fully mixed in the solution, ensuring uniform distribution of each component. At the same time, the diffusion rate of substances is accelerated and solid agglomeration is reduced. Optionally, the following method is used for stirring:

[0055] First, place the biomass powder impregnation solution in an ultrasonic device for ultrasonic oscillation and magnetic stirring for 60 - 90 minutes (such as 65 minutes, 70 minutes, 75 minutes, 80 minutes, 85 minutes). Second, the ultrasonic - oscillated biomass powder impregnation solution is placed in a constant - temperature water bath at a water temperature of 50 - 60 °C for magnetic stirring and impregnation for at least 20 hours (such as 21 hours, 22 hours, 23 hours, 24 hours).

[0056] Ultrasonic oscillation and magnetic stirring can generate strong mechanical vibration and cavitation effect, making solid particles more evenly dispersed in the liquid.

[0057] Before step S3, it also includes the step of obtaining dry biomass powder. Optionally, the pre-dried biomass powder is prepared through the following steps:

[0058] Crush the biomass raw material with a crusher and screen it with a 60-mesh to 80-mesh sieve to obtain biomass powder; dry the biomass powder at 90 - 120 °C for 4 - 6 hours to obtain the pre-dried biomass powder. The dried biomass powder is more easily and evenly dispersed in the mixed solution, and the biomass powder screened by a 60-mesh to 80-mesh sieve is not prone to agglomeration when dispersed in the mixed solution, and the biomass powder with this particle size can also ensure the mechanical properties of the subsequent prepared adsorbent material. Among them, the biomass raw material can be selected as rice husk, corn cob, log, sawed wood, etc., and corn cob with rich sources and low price is preferred.

[0059] Step S4: Dry the biomass powder impregnating solution to obtain a solid intermediate material, and pyrolyze the solid intermediate material at 500 - 700 °C to obtain a solid adsorbent material.

[0060] By pyrolyzing at 500 - 700 °C, the biomass powder in the biomass powder impregnating solution is pyrolyzed into biomass semi-coke. Figure 2 It is a scanning electron microscope image of biomass semi-coke shown according to an exemplary embodiment. Combining Figure 2 , the biomass semi-coke has a loose porous structure. Furthermore, solid substances such as magnesium oxide, lithium nitrate, and potassium acetate are evenly attached to the surface of the biomass semi-coke, and the porous structure is utilized to increase the attachment points of magnesium oxide and basic sites. Among them, when the pyrolysis temperature is set in the range of 500 - 700 °C, the biomass powder can form biomass semi-coke as much as possible.

[0061] Among them, drying the biomass powder impregnating solution to obtain a solid intermediate material includes: drying in an oven at 100 - 110 °C for 12 hours. Crush the dried solid material and screen it through 60- and 80-mesh sieves, and use the 60 - 80-mesh sieve fraction as the solid intermediate material. Then, pyrolyze the solid intermediate material using a tube furnace, specifically with a target temperature of 550 - 650 °C (such as 580 °C, 600 °C, 620 °C), a nitrogen flow rate of 300 - 400 mL / min, a heating rate of 5 - 10 °C / min, and an isothermal period of 30 min.

[0062] Step S5: Mix the solid adsorbent material, deionized water, and binder, and perform shaping treatment on the obtained mixture to obtain a carbon dioxide solid adsorbent.

[0063] Specifically, mix according to the mass ratio of solid adsorption material, deionized water, and binder of 15 - 20:6 - 10:1, stir with a stirrer for 4 - 8 hours (such as 5 hours, 6 hours, 7 hours, etc.), and let stand for at least 10 hours (such as 12 hours, 14 hours, 16 hours, etc.). In this way, ensure the uniform mixing of deionized water, binder, and adsorption material. The mass ratio of solid adsorption material, deionized water, and binder is 18:10:1.

[0064] Among them, the binder is preferably high-temperature resistant alumina and silica. The prepared solid carbon dioxide adsorbent can be reused through high-temperature desorption, and the structural damage of the adsorbent during high-temperature desorption can be reduced.

[0065] In addition, there is no limitation on the shaping process. For example, the mixture can be shaped into a hollow columnar structure, a honeycomb structure, a hollow spherical structure, etc. It should be noted that the advantage of the dosage of magnesium oxide in step S2 is reflected during the shaping process. Using the ratio in step S2 (that is, adding 15 - 20 parts by mass of magnesium oxide powder to 100 parts by mass of the alkali metal salt solution) ensures the physical properties and forming effect of the final adsorbent.

[0066] In summary, the method for preparing a solid carbon dioxide adsorbent provided in the embodiment of the present application uses biomass semicoke obtained by low-temperature pyrolysis of biomass materials. The finally prepared solid adsorbent has a developed pore structure, a large specific surface area, and a strong alkaline metal loading capacity, effectively improving the carbon dioxide adsorption capacity of the adsorbent. In addition, biomass materials with wide sources and low prices are used, effectively reducing the production cost of solid adsorption materials.

[0067] In the second aspect, the present application provides a solid carbon dioxide adsorbent, which is prepared by the above preparation method.

[0068] The solid carbon dioxide adsorbent uses semicoke as the skeleton, increasing the contact area between the overall adsorbent and the gas. At the same time, under the action of lithium nitrate and potassium acetate, the surface of the adsorbent has more basic sites to improve the carbon dioxide adsorption capacity.

[0069] Based on the above description of the solution, specific embodiments are provided below.

[0070] Example 1

[0071] Step 1: Dissolve lithium nitrate (LiNO 3 ) and potassium acetate (CH 3 COOK) in demineralized water respectively to prepare solutions with a concentration of 0.3 mol / L, and mix the two solutions in equal volume to obtain an alkali metal salt solution;

[0072] Step 2: Calcinate magnesium carbonate in a muffle furnace at a temperature of 600 °C, with a programmed heating rate of 5 °C / min. After reaching the target temperature, calcine for 2.5 hours, and then obtain magnesium oxide powder after cooling;

[0073] Step 3: Add the magnesium oxide powder obtained in Step 2 to the alkali metal salt solution prepared in Step 1 and stir evenly to obtain a mixed solution. The mass ratio of magnesium oxide powder to alkali metal salt solution is 15:100;

[0074] Step 4: Crush and grind the biomass raw material, then screen it through 60-mesh and 80-mesh sieves. Take the biomass powder with a particle size of 60 - 80 mesh and dry it in an oven at 105 °C for 6 hours to obtain dried biomass powder;

[0075] Step 5: Add the dried biomass powder to the mixed solution obtained in Step 3 (35 g of biomass sample per 100 mL of the mixed solution B) to obtain a biomass powder impregnation solution. Seal the biomass powder impregnation solution with plastic wrap, then shake it in an ultrasonic device and stir magnetically for 70 min, and then transfer it to a constant temperature water bath (water temperature 55 °C) and stir magnetically and impregnate for 24 hours;

[0076] Step 6: Dry the biomass powder impregnation solution after stirring in Step 5 in an oven at 105 °C for 12 hours. After drying, crush it and screen it through 60-mesh and 80-mesh sieves. Take the fraction with a particle size of 60 - 80 mesh and pyrolyze it at low temperature in a tubular furnace to prepare a solid adsorption material. Tubular furnace settings: N 2 The flow rate is 300 mL / min, the heating rate is 5 °C / min, the target temperature is 600 °C, and keep the temperature constant for 30 min.

[0077] Step 7: Add the solid adsorption material prepared in Step 6, deionized water and silica, and stir with a stirrer for 5 - 7 hours, then let it stand for 12 hours, and press it into a hollow columnar shape with a mold. The mass ratio of the solid adsorption material, deionized water and silica in the carbon dioxide solid adsorbent is 18:10:1.

[0078] Figure 3 is the scanning electron microscope image of the carbon dioxide solid adsorbent prepared according to Example 1, Figure 4 is the transmission electron microscope image of the carbon dioxide solid adsorbent prepared according to Example 1. Table 1 is the performance comparison table of the carbon dioxide solid adsorbent prepared in Example 1 and the conventional magnesium oxide adsorbent.

[0079] Table 1

[0080]

[0081] Combined with Figure 3 、 Figure 4As shown in Table 1, it can be seen that the specific surface area and pore volume of the carbon dioxide adsorbent prepared by the process provided in the embodiments of the present application are significantly improved, and its adsorption capacity for CO 2 also increases significantly.

[0082] Among them, the specific surface area and pore volume are measured and obtained by a nitrogen physical adsorption instrument (BET); the adsorption capacity of CO 2 is measured by a thermogravimetric analyzer. The measurement method is as follows: Weigh 5 mg of the sample and place it in the crucible of the thermogravimetric analyzer. Under the atmosphere of high-purity nitrogen (N 2 with a flow rate of 20 mL / min), heat it to 110 °C at a rate of 10 °C·min -1 , keep it at a constant temperature for 30 min, and then heat it to 300 °C at a rate of 10 °C·min -1 , keep it at a constant temperature for 30 min, and then switch the gas path to high-purity CO 2 , and keep it at a constant temperature for 1 h.

[0083] Example 2

[0084] Step 1: Dissolve lithium nitrate (LiNO 3 ) and potassium acetate (CH 3 COOK) in deionized water to prepare solutions with a concentration of 0.3 mol / L, and mix the two solutions in equal volumes to obtain an alkali metal salt solution;

[0085] Step 2: Calcinate magnesium carbonate in a muffle furnace. Set the temperature to 600 °C, the programmed heating rate to 5 °C / min, and the calcination time to 2.5 hours after reaching the target temperature. After cooling, obtain magnesium oxide powder;

[0086] Step 3: Add the magnesium oxide powder obtained in Step 2 to the alkali metal salt solution prepared in Step 1, and stir evenly to obtain a mixed solution. The mass ratio of the magnesium oxide powder to the alkali metal salt solution is 22:100;

[0087] Step 4: Crush and grind the biomass raw material through a crusher and then screen it through 60- and 80-mesh sieves. Take the 60-80-mesh biomass powder and dry it in an oven at 105 °C for 6 hours to obtain dry biomass powder;

[0088] Step 5: Add the dry biomass powder to the mixed solution obtained in Step 3 (35 g of biomass sample per 100 mL of the B mixed solution) to obtain a biomass powder impregnation solution. Seal the biomass powder impregnation solution with plastic wrap, then shake it in an ultrasonic device and stir magnetically for 70 min, and then transfer it to a constant temperature water bath (water temperature 55 °C) and stir magnetically and impregnate for 24 hours;

[0089] Step 6: The biomass powder impregnation solution after stirring in Step 5 is dried in an oven at 105 °C for 12 hours, crushed after drying, sieved through 60- and 80-mesh sieves, and the 60-80 mesh sieve fraction is taken and pyrolyzed at low temperature in a tube furnace to prepare a solid adsorbent material. Tube furnace settings: N 2 The flow rate is 300 mL / min, the heating rate is 5 °C / min, the target temperature is 600 °C, and the constant temperature is 30 min.

[0090] Step 7: The solid adsorbent material prepared in Step 6 is added with deionized water and silica, stirred with a stirrer for 5-7 hours, left standing for 12 hours, and pressed into a hollow column shape with a mold. The mass ratio of the solid adsorbent material, deionized water and silica in the carbon dioxide solid adsorbent is 18:10:1.

[0091] Figure 5 is the scanning electron microscope image of the carbon dioxide solid adsorbent prepared according to Example 2, Figure 6 is the transmission electron microscope image of the carbon dioxide solid adsorbent prepared according to Example 2. Table 2 is the performance comparison table of the carbon dioxide solid adsorbent prepared in Example 2 and the conventional magnesium oxide adsorbent.

[0092] Table 2

[0093]

[0094] Among them, the specific surface area and pore volume are measured and obtained by a nitrogen physical adsorption instrument (BET); the adsorption capacity of CO 2 is measured by a thermogravimetric analyzer. Measurement method: Weigh 5 mg of the sample and place it in the crucible of the thermogravimetric analyzer. Under the atmosphere of high-purity nitrogen (N 2 with a flow rate of 20 mL / min), heat it to 110 °C at a rate of 10 °C·min -1 , keep the temperature constant for 30 min, and then heat it to 300 °C at a rate of 10 °C·min -1 , keep the temperature constant for 30 min, and then switch the gas path to high-purity CO 2 , and keep the temperature constant for 1 h.

[0095] Combined with Figure 5 , Figure 6 and Table 2, it can be seen that the specific surface area and pore volume of the carbon dioxide adsorbent prepared by the process provided in the embodiment of the present application have been significantly improved compared with magnesium oxide, and its adsorption capacity for CO 2 has also increased significantly.

[0096] However, compared with Example 1, the ratio of magnesium oxide to the alkali metal salt solution was increased in Step 3 of Example 2 (the specific mass parts of magnesium oxide and the alkali metal solution in Example 2 are 22:100), resulting in carrier agglomeration on the surface of the finally prepared adsorbent. Especially when comparing Figure 4 andFigure 6 , through comparison of transmission electron microscope images, it can be seen that Figure 6 in Example 2 of [reference], obvious agglomeration phenomenon appears on the surface of the prepared adsorption reagent. Through comparison of Table 1 and Table 2, from the three aspects of specific surface area, pore volume, and CO 2 adsorption capacity, the adsorbent prepared in Example 1 is superior to the adsorbent prepared in Example 2.

[0097] It can be seen that through the comparison and verification of Example 1 and Example 2, the dosage of magnesium oxide in Step 3 is directly related to the morphology and performance of the finally prepared adsorbent. As the ratio of magnesium oxide to the alkali metal salt solution increases, agglomeration phenomenon is likely to appear on the surface of the finally prepared adsorbent. Even if the mixed material is fully stirred in the steps after Step 3, the surface agglomeration of the finally prepared reagent cannot be avoided.

[0098] Example 3

[0099] Step 1: Dissolve lithium nitrate (LiNO 3 ) and potassium acetate (CH 3 COOK) in demineralized water to prepare solutions with a concentration of 0.3 mol / L, and mix the two solutions in equal volumes to obtain an alkali metal salt solution;

[0100] Step 2: Calcinate magnesium carbonate in a muffle furnace, set the temperature at 600 °C, set the programmed heating rate at 5 °C / min, keep the temperature at the target temperature for 2.5 hours, and obtain magnesium oxide powder after cooling;

[0101] Step 3: Add the magnesium oxide powder obtained in Step 2 to the alkali metal salt solution prepared in Step 1, and stir evenly to obtain a mixed solution. The mass ratio of the magnesium oxide powder to the alkali metal salt solution is 15:100;

[0102] Step 4: Crush and grind the biomass raw material with a crusher, then screen it through 60-mesh and 80-mesh sieves. Take the biomass powder with a particle size of 60 - 80 mesh and dry it in an oven at 105 °C for 6 hours to obtain dry biomass powder;

[0103] Step 5: Add the dry biomass powder to the mixed solution obtained in Step 3 (35 g of biomass sample per 100 mL of the B mixed solution) to obtain a biomass powder impregnation solution. Seal the biomass powder impregnation solution with plastic wrap, then shake it in an ultrasonic device and stir magnetically for 70 min, and then transfer it to a constant temperature water bath (water temperature 55 °C) and stir magnetically and impregnate for 24 hours;

[0104] Step 6: Dry the biomass powder impregnation solution after stirring in Step 5 in an oven at 105 °C for 12 hours, crush it after drying, screen it through 60-mesh and 80-mesh sieves, take the fraction with a particle size of 60 - 80 mesh, and pyrolyze it at low temperature in a tube furnace to prepare a solid adsorption material. Tube furnace settings: N2 The flow rate is 300 mL / min, the heating rate is 5 °C / min, the target temperature is 800 °C, and the constant temperature is 30 min.

[0105] Step 7: Add the solid adsorbent material prepared in Step 6 to deionized water and silica, stir with a stirrer for 5 - 7 hours, let it stand for 12 hours, and press it into a hollow columnar shape with a mold. The mass ratio of the solid adsorbent material, deionized water, and silica in the carbon dioxide solid adsorbent is 18:10:1.

[0106] Table 3 is a performance comparison table of the carbon dioxide solid adsorbent prepared in Example 3 and the conventional magnesium oxide adsorbent.

[0107] Table 3

[0108]

[0109] Among them, the specific surface area and pore volume are measured and obtained by a nitrogen physical adsorption instrument (BET); the adsorption capacity of CO 2 is measured by a thermogravimetric analyzer. The measurement method: Weigh 5 mg of the sample and place it in the crucible of the thermogravimetric analyzer. Under the atmosphere of high-purity nitrogen (N 2 with a flow rate of 20 mL / min), heat it to 110 °C at a rate of 10 °C·min -1 , keep it at a constant temperature for 30 min, and then heat it to 300 °C at a rate of 10 °C·min -1 , keep it at a constant temperature for 30 min, and then switch the gas path to high-purity CO 2 , and keep it at a constant temperature for 1 h.

[0110] Combined with Table 3, it can be seen that the specific surface area and pore volume of the carbon dioxide adsorbent prepared by the process provided in Example 3 of the present application have been significantly improved compared with magnesium oxide, and its adsorption capacity for CO 2 has also increased significantly.

[0111] However, compared with Example 1, in Example 3, since the preparation temperature of the solid adsorbent material in Step 6 is increased to 800 °C, the specific surface area and pore volume of the prepared adsorbent decrease, and the CO 2 adsorption capacity also decreases compared with Example 1. This is mainly because when the pyrolysis temperature is too high, the graphitization degree of the char produced by biomass pyrolysis intensifies, resulting in a reduction in the pore structure of the adsorbent material. Through the comparison of Table 1 and Table 2, from the three aspects of specific surface area, pore volume, and CO 2 adsorption capacity, the adsorbent prepared in Example 1 is better than the adsorbent prepared in Example 3.

[0112] It can be seen that through the comparison and verification of Example 1 and Example 3, the preparation temperature of the solid adsorbent material in Step 6 affects the characteristics of the final solid adsorbent material and the CO 2 adsorption capacity.

[0113] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope recorded in this specification.

[0114] The above-described embodiments only represent several implementation manners of the present application. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the appended claims.

Claims

1. A method for preparing a solid carbon dioxide adsorbent, characterized in that: The method comprises: An alkali metal salt solution with a concentration of 0.2-0.6 mol / L is prepared using a metal salt, wherein the metal salt is selected from lithium nitrate and potassium acetate; Adding 15-20 parts by mass of magnesium oxide powder to 100 parts by mass of the alkali metal salt solution, and stirring to obtain a mixed solution; Adding pre-dried biomass powder to the mixed solution to obtain a biomass powder impregnation liquid, and mixing and stirring the biomass powder impregnation liquid, wherein 30-40 g of the biomass powder is added to every 100 ml of the mixed solution; Drying the biomass powder impregnation liquid to obtain a solid intermediate material, and pyrolyzing the solid intermediate material at 500-700° C. to obtain a solid adsorption material; The solid adsorbent material, deionized water and a binder are mixed, and the obtained mixture is subjected to shaping treatment to obtain the solid adsorbent for carbon dioxide.

2. The preparation method according to claim 1, characterized in that: The alkali metal salt solution with a concentration of 0.2-0.6 mol / L using a metal salt comprises: Use deionized water to prepare 0.3-0.5 mol / L lithium nitrate solution and potassium acetate solution respectively; The lithium nitrate solution and the potassium acetate solution are mixed in equal volumes to obtain the alkali metal salt solution.

3. The preparation method according to claim 1, characterized in that: The pre-dried biomass powder is prepared by the following steps: The biomass raw material is crushed by a crusher and sieved with a 60-80 mesh sieve to obtain biomass powder; the biomass powder is dried at 100-120° C. for 4-6 hours to obtain the pre-dried biomass powder.

4. The preparation method according to claim 3, characterized in that: The mixing and stirring of the biomass powder impregnation liquid comprises: The biomass powder impregnation liquid is placed in an ultrasonic device for ultrasonic oscillation and magnetic stirring for 60-90 minutes; The biomass powder impregnation liquid after ultrasonic vibration is placed in a constant temperature water bath pot at a water temperature of 50-60° C. and magnetically stirred and impregnated for at least 20 hours.

5. The preparation method according to claim 1, characterized in that: The step of drying the biomass powder impregnation liquid to obtain a solid intermediate material comprises: Drying the biomass powder impregnation solution at 100-110° C. for at least 12 hours; The dried solid material was crushed and sieved through 60 and 80 mesh sieves, and the 60-80 mesh sieve was used as the solid intermediate material.

6. The preparation method according to claim 5, characterized in that: The solid intermediate material is pyrolyzed at 500-700° C. to obtain a solid adsorption material, comprising: A tubular furnace was used with a target temperature of 550-650°C, a nitrogen flow rate of 300-400 mL / min, a heating rate of 5-10°C / min, and a constant temperature of 30 min.

7. The preparation method according to claim 1, characterized in that: The binder is selected from alumina and silicon oxide, and the solid adsorption material, deionized water and the binder are mixed, comprising: The solid adsorption material, deionized water and adhesive are mixed in a mass ratio of 15-20:6-10:1, stirred for 4-8 hours, and allowed to stand for at least 10 hours.

8. The preparation method according to claim 7, characterized in that: The mass ratio of the solid adsorption material, deionized water and adhesive is 18:10:

1.

9. The preparation method according to any one of claims 1 to 8, characterized in that: Before adding 15-20 parts by mass of magnesium oxide powder to 100 parts by mass of the alkali metal salt solution, the method further comprises: The magnesium carbonate is calcined at a target temperature of 500-700° C. and a heating rate of 5° C. / min. After reaching the target temperature, the magnesium carbonate is calcined for 2-3 hours, and the magnesium oxide powder is obtained after cooling.

10. A solid adsorbent for carbon dioxide, characterized in that: The carbon dioxide solid adsorbent is prepared by the preparation method described in any one of claims 1 to 9.

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