Carbon dioxide adsorbents, preparation methods and applications

Abstract

This application relates to the technical field of carbon dioxide treatment in hydrocarbon materials, specifically to carbon dioxide adsorbents, preparation methods, and applications. The preparation method includes: preparing microspheres formed from alkali metal or alkali metal solution, alumina precursor, and silica; loading the microspheres with organic amines and / or subjecting them to a first calcination. The carbon dioxide adsorbent prepared using this method can be applied to the removal of high-content CO2 in the ethylene product section of the MTO olefin separation process, exhibiting advantages such as high selectivity, large capacity, high adsorption precision, and strong cycle stability.

Description

Technical Field

[0001] This application relates to the technical field of carbon dioxide treatment in hydrocarbon materials, specifically to carbon dioxide adsorbents, preparation methods, and applications. Background Technology

[0002] Currently, olefins are mainly produced via MTO (Made-to-Oxygen) process, but the product gas inevitably contains carbon dioxide, with concentrations reaching as high as 500 ppm. The industry currently primarily uses alkaline washing to remove carbon dioxide from the product gas in the olefin separation section of MTO units. Because the product gas contains a large amount of oxygen-containing compounds such as aldehydes and ketones, these compounds undergo aldol condensation during alkaline washing, producing a yellow-red polymer commonly known as "butter." This butter is generally discharged from the alkaline washing tower with the waste alkaline solution. The generation of butter negatively impacts the long-term stable operation of the unit, potentially leading to substandard alkaline washing and consequently affecting downstream production. Large amounts of butter can clog tower internals, shortening the tower's operating cycle. Furthermore, the generated butter is classified as hazardous waste, resulting in high treatment costs. The waste alkaline solution is rich in oils and fats, with a COD value as high as 20,000–60,000 mg / L and a pH of 14. It also contains a large amount of carbonates, making it a difficult-to-treat waste liquid. It is typically incinerated in an incinerator, requiring a large amount of fuel gas, resulting in high operating costs and significant carbon dioxide emissions.

[0003] In addition to alkaline washing to remove carbon dioxide from product gas, developing a new type of fixed-bed adsorbent suitable for carbon dioxide removal from product gas in MTO units to replace the traditional wet alkaline washing technology is an effective way to solve carbon dioxide removal and save energy.

[0004] Patent document CN113680334A discloses a carbon dioxide adsorbent, its preparation method, and its application. This adsorbent consists of a support and acid radicals attached to the support. The support is composed of natural biomaterials, a covalent organic framework material, activated carbon, and polyvinyl chloride. This adsorbent has the advantages of low energy consumption and high adsorption efficiency. However, the covalent organic framework material in the support has certain stability issues, and the preparation of the covalent organic framework is a complex process. Furthermore, tetrahydrofuran is used as a solvent in the adsorbent preparation process, which is harmful to human health.

[0005] Patent document CN107376826B discloses a calcium oxide-based high-temperature CO2 adsorbent and its preparation method. This adsorbent uses alumina, silica, magnesium aluminum spinel, and molecular sieves as carriers, with calcium oxide as the main active component and the addition of certain structural stabilizing agents. The preparation method is simple, produces no wastewater, is environmentally friendly, and is easily reproducible, exhibiting high activity. However, it suffers from low adsorption precision and exhibits poor stability after multiple adsorption-desorption cycles, with a significant decrease in adsorption capacity that increases with the number of adsorption-desorption cycles.

[0006] Patent document CN107970877A discloses a method for preparing a modified porous alumina decarburizing agent. It employs a co-precipitation method to decarburize Al... 3+ A composite colloid was prepared by mixing the colloid with soluble salts of alkaline earth metals and transition metals. Then, alkali metal salts and molecular sieves were added as additives and directly mixed in solution. After centrifugation, washing, drying, and calcination, a powder was obtained, which was then shaped with a binder. This adsorbent exhibits high breakthrough adsorption capacity, high decarbonization selectivity, and high removal precision. However, waste liquid was inevitably generated during the preparation process, requiring post-treatment and increasing treatment costs.

[0007] In conclusion, developing a carbon dioxide adsorbent with both high capacity and high precision is of great significance for the application of solid carbon dioxide adsorbents in the MTO olefin separation process for CO2 removal. Summary of the Invention

[0008] In view of this, the carbon dioxide adsorbent, preparation method, and application provided in the embodiments of this application at least solve one of the above-mentioned technical problems to a certain extent. Therefore, the embodiments of this application disclose at least the following technical solutions:

[0009] In a first aspect, embodiments of this application disclose a method for preparing a carbon dioxide adsorbent, wherein the carbon dioxide adsorbent is used to adsorb carbon dioxide from hydrocarbon materials, and the preparation method includes:

[0010] Microspheres formed from alkali metal or alkali metal solution, alumina precursor and silicon oxide were prepared.

[0011] The microspheres are loaded with organic amines and / or subjected to a first calcination.

[0012] Secondly, embodiments of this application disclose a carbon dioxide adsorbent prepared by the preparation method described in the first aspect.

[0013] Thirdly, embodiments of this application disclose the application of the carbon dioxide adsorbent prepared by the preparation method described in the first aspect in the adsorption of carbon dioxide in hydrocarbon materials.

[0014] The carbon dioxide adsorbent provided in this application embodiment can be applied to the removal of high CO2 content in the ethylene product section of the MTO olefin separation process, and has the advantages of high selectivity, large capacity, high adsorption accuracy and strong cycle stability.

[0015] The raw materials used in the preparation method provided in this application are readily available, the production process is simple and applicable, it has high market competitiveness, and it is suitable for large-scale industrial production and application.

[0016] The preparation method provided in this application achieves zero waste liquid generation during the preparation process, is environmentally friendly, avoids water pollution, and solves the problem of waste liquid treatment.

[0017] The embodiments of this application employ a mechanical mixing method, in which alumina and silicon oxide are in a mechanically mixed state, without producing a molecular sieve morphology. This solves the problem of adsorption heat generated by molecular sieves during the adsorption of high-content carbon dioxide, ensuring safety during use.

[0018] In this application, the adsorbent is calcined at high temperature with ammonia gas. Nitrogen species gradually replace oxygen atoms in the oxides of the adsorbent, resulting in an adsorbent containing basic nitrogen oxides. The presence of nitrogen enhances the adsorption of carbon dioxide on the surface, effectively adsorbing carbon dioxide and improving the adsorption precision of the adsorbent. In another application, the adsorbent is modified with organic amines to obtain a CO2 adsorbent material with a high density of adsorption sites. The content of acidic functional groups in the adsorbent decreases, while the content of basic functional groups increases, enhancing chemisorption and improving the adsorption precision and capacity of the adsorbent. Attached Figure Description

[0019] Figure 1 A schematic diagram of the fixed-bed simulated reactor provided in the embodiments of this application. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application. Reagents not specifically described in detail herein are all conventional reagents and are commercially available; methods not specifically described in detail are all conventional experimental methods and can be learned from the prior art.

[0021] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence, nor do they substantially limit the technical features thereafter. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0022] For the purpose of better understanding this application and not limiting its scope, all figures indicating quantities, percentages, and other numerical values ​​used herein should, in all cases, be understood to be modified by the word "approximately." Therefore, unless otherwise stated, the numerical parameters listed in the specification and appended claims are approximate values ​​and may vary depending on the desired properties being sought. Each numerical parameter should at least be considered as obtained based on reported significant figures and through conventional rounding methods.

[0023] In a first aspect, embodiments of this application disclose a method for preparing a carbon dioxide adsorbent, wherein the carbon dioxide adsorbent is used to adsorb carbon dioxide from hydrocarbon materials, and the preparation method includes:

[0024] Microspheres formed from alkali metal or alkali metal solution, alumina precursor and silicon oxide were prepared.

[0025] The microspheres are loaded with organic amines and / or subjected to a first calcination.

[0026] In this application, "hydrocarbon materials" refers to product gas prepared by the MTO process, and the main products in the product gas include various olefins such as ethylene and propylene, as well as carbon dioxide.

[0027] In the embodiments of this application, the microspheres are loaded with organic amines or the microspheres are calcined at high temperature in ammonia to obtain a CO2 adsorption material with high density of adsorption sites or an adsorbent containing basic nitrogen oxides. The content of acidic functional groups in the adsorbent is reduced and the content of basic functional groups is increased, thereby enhancing chemical adsorption and improving the adsorption precision and adsorption capacity of the adsorbent.

[0028] The raw materials used in the preparation method provided in this application are readily available, the production process is simple and applicable, it has high market competitiveness, and it is suitable for large-scale industrial production and application.

[0029] The preparation method provided in this application achieves zero waste liquid generation during the preparation process, is environmentally friendly, avoids water pollution, and solves the problem of waste liquid treatment.

[0030] The embodiments of this application employ a mechanical mixing method, in which alumina and silicon oxide are in a mechanically mixed state, without producing a molecular sieve morphology. This solves the problem of adsorption heat generated by molecular sieves during the adsorption of high-content carbon dioxide, ensuring safety during use.

[0031] In some embodiments, the conditions for the first calcination include at least one of the following: an atmosphere of ammonia, a stability of 600–800°C, and a time of 2–3 hours. In some embodiments, the conditions for the first calcination include: an atmosphere of ammonia, a stability of 600–800°C, and a time of 2–3 hours. In some embodiments, the conditions for the first calcination include: an atmosphere of ammonia, a stability of 600°C, and a time of 2 hours.

[0032] In some embodiments, the step of loading the microspheres with organic amines includes:

[0033] The microspheres are subjected to a second calcination;

[0034] The organic amine solution is loaded onto the microspheres;

[0035] drying.

[0036] In some embodiments, the calcination conditions include at least one of the following: an atmosphere of air, a temperature of 500–900°C, and a time of 2–3 hours. In some embodiments, the second calcination conditions include at least one of the following: an atmosphere of air, a temperature of 500–900°C, and a time of 2–3 hours. In some embodiments, the second calcination conditions include: an atmosphere of air, a temperature of 600°C, and a time of 2 hours.

[0037] In some embodiments, the organic amine is selected from at least one of diethylenetriamine, triethylenetetramine, tetraethylenepentamine, polyethyleneimine, and ethanolamine. In some embodiments, the organic amine is tetraethylenepentamine.

[0038] In some embodiments, the dispersant for the organic amine is selected from at least one of water, methanol, ethanol, ethylene glycol, and glycerol. In some embodiments, the dispersant for the organic amine is ethylene glycol.

[0039] In some embodiments, the drying conditions include at least one of a temperature of 80–120°C and a time of 4–12 hours. In some embodiments, the drying conditions include a temperature of 80–120°C and a time of 4–12 hours. In some embodiments, the drying conditions include a temperature of 100°C and a time of 6 hours.

[0040] In some embodiments, the alumina precursor is selected from either boehmite or fast sintering powder. In some embodiments, the alumina precursor is boehmite.

[0041] In some embodiments, the silica has a mesoporous channel distribution with a specific surface area of ​​700–1100 m². 2 / g, pore volume 0.6~2.2mL / g, average mesopore diameter 2~25nm.

[0042] In some embodiments, the alkali metal is selected from at least one of lithium, sodium, potassium, magnesium, calcium, and barium;

[0043] In some embodiments, the alkali metal solution is selected from at least one of the nitrates, carbonates, bicarbonates, oxalates, acetates, chlorides, and sulfates of lithium, sodium, potassium, magnesium, calcium, and barium. In some embodiments, the alkali metal solution is a deionized aqueous solution containing at least two of sodium nitrate, potassium nitrate, and magnesium nitrate.

[0044] In some embodiments, the microspheres have also undergone a curing and solidification step.

[0045] Secondly, embodiments of this application disclose a carbon dioxide adsorbent prepared by the method described in the first aspect. The carbon dioxide adsorbent provided in these embodiments can be applied to the removal of high-content CO2 in the ethylene product section of the MTO olefin separation process, and has the advantages of high selectivity, large capacity, high adsorption precision, and strong cycle stability.

[0046] Secondly, embodiments of this application disclose the application of the carbon dioxide adsorbent prepared by the preparation method described in the first aspect in the adsorption of carbon dioxide in hydrocarbon materials.

[0047] The present application will be further described below with reference to non-limiting embodiments. Those skilled in the art will understand that although the following embodiments point to preferred embodiments of the present application, they are given by way of example only, and all reagents used are commercially available.

[0048] Example 1

[0049] Weigh 200g of boehmite and 56g of silica and mechanically mix them. Part of the mixture is then placed in a ball rolling machine for later use.

[0050] Weigh out 0.1 mol of sodium nitrate and 0.2 mol of potassium nitrate, dissolve them in deionized water to prepare solution A, and pour it into a spray bottle for later use;

[0051] Start the ball rolling machine and spray solution A evenly onto the mixed powder to obtain mother balls of 1-2 mm. Then, perform constant temperature curing at 60℃ for 12 hours.

[0052] After curing, the mother ball is placed in a ball rolling machine, the remaining mixed powder is added and the ball rolling continues. Solution A is sprayed evenly to obtain microspheres with a diameter of 2-4 mm. Then, the microspheres are cured at 70℃ for 10 hours. After curing, they are baked at 200℃ for 2 hours.

[0053] The dried microspheres were placed in a tube furnace and calcined at 600°C for 2 hours under an ammonia atmosphere to obtain a nitrogen-doped carbon dioxide adsorbent.

[0054] Example 2

[0055] Weigh 200g of boehmite and 56g of silica and mechanically mix them. Part of the mixture is then placed in a ball rolling machine for later use.

[0056] Weigh out 0.1 mol of sodium nitrate and 0.2 mol of magnesium nitrate, dissolve them in deionized water to prepare solution A, and pour it into a spray bottle for later use;

[0057] Start the ball rolling machine and spray solution A evenly onto the mixed powder to obtain mother balls of 1-2 mm. Then, perform constant temperature curing at 60℃ for 12 hours.

[0058] After curing, the mother ball is placed in a ball rolling machine, the remaining mixed powder is added and the ball rolling continues. Solution A is sprayed evenly to obtain microspheres with a diameter of 2-4 mm. Then, the microspheres are cured at 70℃ for 10 hours. After curing, they are baked at 200℃ for 2 hours.

[0059] The dried microspheres were placed in a tube furnace and calcined at 600°C for 2 hours under an ammonia atmosphere to obtain a nitrogen-doped carbon dioxide adsorbent.

[0060] Example 3

[0061] Weigh 200g of boehmite and 56g of silica and mechanically mix them. Part of the mixture is then placed in a ball rolling machine for later use.

[0062] Weigh out 0.1 mol of sodium nitrate and 0.2 mol of potassium nitrate, dissolve them in deionized water to prepare solution A, and pour it into a spray bottle for later use;

[0063] Start the ball rolling machine and spray solution A evenly onto the mixed powder to obtain mother balls of 1-2 mm. Then, perform constant temperature curing at 60℃ for 12 hours.

[0064] After curing, the mother ball is placed in a ball rolling machine, the remaining mixed powder is added and the ball rolling continues. Solution A is sprayed evenly to obtain microspheres with a diameter of 2-4 mm. Then, the microspheres are cured at 70℃ for 10 hours. After curing, they are baked at 200℃ for 2 hours.

[0065] The dried microspheres were placed in a muffle furnace and calcined at 600℃ for 2 hours.

[0066] 60g of tetraethylenepentamine was weighed and dispersed in ethylene glycol, and the organic amine solution was loaded into the calcined microspheres.

[0067] Microspheres loaded with organic amines were dried at 100°C for 6 hours to obtain an organic amine-modified carbon dioxide adsorbent.

[0068] Example 4

[0069] Weigh 200g of boehmite and 56g of silica and mechanically mix them. Part of the mixture is then placed in a ball rolling machine for later use.

[0070] Weigh out 0.1 mol of sodium nitrate and 0.2 mol of potassium nitrate, dissolve them in deionized water to prepare solution A, and pour it into a spray bottle for later use;

[0071] Start the ball rolling machine and spray solution A evenly onto the mixed powder to obtain mother balls of 1-2 mm. Then, perform constant temperature curing at 60℃ for 12 hours.

[0072] After curing, the mother ball is placed in a ball rolling machine, the remaining mixed powder is added and the ball rolling continues. Solution A is sprayed evenly to obtain microspheres with a diameter of 2-4 mm. Then, the microspheres are cured at 70℃ for 10 hours. After curing, they are baked at 200℃ for 2 hours.

[0073] The dried microspheres were placed in a muffle furnace and calcined at 600℃ for 2 hours.

[0074] 100g of tetraethylenepentamine was weighed and dispersed in ethylene glycol, and the organic amine solution was loaded into the calcined microspheres.

[0075] Microspheres loaded with organic amines were dried at 100°C for 6 hours to obtain an organic amine-modified carbon dioxide adsorbent.

[0076] Comparative Example 1

[0077] Weigh 200g of boehmite and 56g of silica and mechanically mix them. Part of the mixture is then placed in a ball rolling machine for later use.

[0078] Weigh out 0.1 mol of sodium nitrate and 0.2 mol of potassium nitrate, dissolve them in deionized water to prepare solution A, and pour it into a spray bottle for later use;

[0079] Start the ball rolling machine and spray solution A evenly onto the mixed powder to obtain mother balls of 1-2 mm. Then, perform constant temperature curing at 60℃ for 12 hours.

[0080] After curing, the mother ball is placed in a ball rolling machine, the remaining mixed powder is added and the ball rolling continues. Solution A is sprayed evenly to obtain microspheres with a diameter of 2-4 mm. Then, the microspheres are cured at 70℃ for 10 hours. After curing, they are baked at 200℃ for 2 hours.

[0081] The dried microspheres were placed in a muffle furnace and calcined at 600°C for 2 hours to obtain a carbon dioxide adsorbent.

[0082] Comparative Example 2

[0083] Weigh 200g of boehmite and 56g of silica and mix them mechanically, then place them in a ball rolling machine for later use;

[0084] Weigh out 0.1 mol of sodium nitrate and 0.2 mol of potassium nitrate, dissolve them in deionized water to prepare solution A, and pour it into a spray bottle for later use;

[0085] Start the ball rolling machine and spray solution A evenly onto the mixed powder to obtain microspheres with a diameter of 2-4 mm. Dry them at 200℃ for 2 hours.

[0086] The dried microspheres were placed in a tube furnace and calcined at 600°C for 2 hours under an ammonia atmosphere to obtain a nitrogen-doped carbon dioxide adsorbent.

[0087] Comparative Example 3

[0088] Weigh 200g of boehmite and 56g of silica and mechanically mix them. Part of the mixture is then placed in a ball rolling machine for later use.

[0089] Start the ball rolling machine and spray deionized water evenly onto the mixed powder to obtain mother balls of 1-2 mm. Then, perform constant temperature curing at 60℃ for 12 hours.

[0090] After curing, the mother ball is placed in a ball rolling machine, the remaining mixed powder is added and the ball rolling continues. Deionized water is sprayed evenly to obtain microspheres with a diameter of 2-4 mm. Then, the microspheres are cured at 70℃ for 10 hours. After curing, they are baked at 200℃ for 2 hours.

[0091] The dried microspheres were placed in a muffle furnace and calcined at 600℃ for 2 hours.

[0092] 100g of tetraethylenepentamine was weighed and dispersed in ethylene glycol, and the organic amine solution was loaded into the calcined microspheres.

[0093] Microspheres loaded with organic amines were dried at 100°C for 6 hours to obtain an organic amine-modified carbon dioxide adsorbent.

[0094] The physicochemical properties and CO2 adsorption performance of the adsorbents prepared in the specific embodiments 1-4 and comparative examples 1-3 of this application were tested. The main physicochemical properties and application operating conditions of the adsorbents are shown in Table 1, and the evaluation results are shown in Table 2.

[0095] Table 1. Main physicochemical properties and application conditions of the adsorbent.

[0096]

[0097] Test conditions: In this experiment, a self-designed and assembled tubular gas-phase fixed-bed CO2 adsorption reaction system was used. A simplified diagram of the apparatus is attached. Figure 1 This experiment evaluated the adsorption performance of carbon dioxide in ethylene feedstock. The CO2 content at the inlet of the feedstock gas (CO2 / ethylene) was controlled at approximately 1000–3000 ppm, and the space velocity was 1000–3000 h⁻¹. -1 The adsorption temperature was 30℃. The adsorption bed was filled with the original particle size. After the prepared adsorbent was sieved through a sample sieve, 30 ml of catalyst was measured with a graduated cylinder and added in small amounts multiple times to a self-made stainless steel microreactor with a diameter of 20 mm. The height-to-diameter ratio of the catalyst bed was controlled to be 2-5. The flow rate of the simulated gas was controlled by a mass flow meter, and the adsorption-desorption temperature was controlled by a heater. At the same time, the CO2 concentration at the inlet and outlet of the fixed bed reactor was measured online by a gas chromatograph. The outlet CO2 concentration was tested every 10 min, and the detection limit was 0.02 ppm.

[0098] By analyzing the CO2 content C at the inlet and outlet 进 C 出 The adsorption performance of the adsorbent for CO2 is comprehensively evaluated by measuring parameters such as the real-time space velocity (Sv) of the feed gas, the CO2 absorption time (t), and the bulk density (d) of the adsorbent bed. When 0.1 ppm of CO2 is detected in the reactor tail gas three consecutive times, the adsorbent is considered deactivated, and the adsorption capacity (S) at this point is calculated using the following formula:

[0099]

[0100] Wherein, S represents the adsorption capacity;

[0101] m s —The mass of CO2 adsorbed by the catalyst during the experiment, in grams;

[0102] M—mass of catalyst loaded, in grams;

[0103] C 进 C 出 —CO2 content at the inlet and outlet of the experimental apparatus, g / m 3 ;

[0104] S v —Gas space velocity during the experiment, h -1 ;

[0105] t — Time required for experimental penetration, in hours;

[0106] d——catalyst bulk density, g / ml.

[0107] Under the above test conditions, the adsorbents prepared in Examples 1-4 and Comparative Examples 1-3 were subjected to... Figure 1 The adsorption performance was evaluated under the evaluation procedure, and the radial compressive strength of the prepared adsorbent was tested according to HG / T2782-2011. The test results are shown in Table 2.

[0108] Table 2. Test results of adsorbent samples from Examples 1-4 and Comparative Examples 1-3.

[0109]

[0110]

[0111] As shown in Table 2, the adsorption capacity of the carbon dioxide adsorbents provided in Examples 1-4 is significantly higher than that in Comparative Examples 1-3. This indicates that the carbon dioxide adsorbents prepared by the method provided in the embodiments of this application can improve the adsorption capacity of carbon dioxide and are more conducive to the removal of carbon dioxide from hydrocarbon materials.

[0112] Specifically, compared with Comparative Example 1, the adsorption properties of the modified adsorbents in Examples 1-4 were significantly improved. The adsorption precision (comparing the outlet carbon dioxide content, the unmodified Comparative Example 1 had a content of less than 0.5 ppm, while the modified Examples 1-4 had a content of less than 0.1 ppm) and adsorption capacity were both increased, indicating that the modification of the adsorbent was effective. The adsorbent was calcined with ammonia (first calcination), gradually replacing oxygen atoms in the oxides with nitrogen species, resulting in an adsorbent containing basic nitrogen oxides. The adsorbent was modified with organic amines to obtain a CO2 adsorbent material with a high density of adsorption sites. The content of acidic functional groups decreased while the content of basic functional groups increased, enhancing chemisorption and improving the adsorption precision and capacity.

[0113] Specifically, compared with Example 1, the nitrogen-doped carbon dioxide adsorbent obtained in Comparative Example 2, which did not undergo constant temperature curing and solidification, showed significantly worse adsorption capacity and radial compressive strength than that of Example 1. This indicates that the constant temperature curing and solidification process is beneficial to the adsorption performance and compressive strength of the adsorbent.

[0114] Specifically, compared with Example 4, Comparative Example 3 did not load metal ions, and its adsorption capacity decreased significantly. Metal ions containing strong attraction for outer electrons can coordinate with CO2, which improves the adsorption performance of the adsorbent for CO2. In addition, introducing metal ions into the adsorbent can change the specific surface area and pore volume of the material, thereby affecting its physical adsorption.

[0115] An experimental example also investigated the process conditions such as space velocity, concentration, and reaction temperature of the carbon dioxide adsorbent provided in Example 1. The results of different process conditions and adsorption capacity are shown in Tables 3, 4, and 5.

[0116] Table 3 Adsorption capacity of adsorbent under different feed gas concentrations

[0117]

[0118] Table 4 Adsorption capacity at different space velocities

[0119]

[0120] Table 5 Adsorption capacity at different reaction temperatures

[0121]

[0122] The above experimental evaluation results show that the adsorbent provided in the examples has a high adsorption capacity under different operating conditions, indicating that the adsorbent has strong resistance to fluctuations in raw material impurity content, space velocity, and reaction temperature, and can adapt to complex and variable operating conditions and impurity content. It is especially suitable for the purification of high carbon dioxide content in MTO olefin separation units.

[0123] The regeneration activity evaluation test of the adsorbent provided in the examples:

[0124] The saturated adsorbent was placed in a tubular regeneration reactor, and the CO2 content at the outlet was tested online using gas chromatography. Heated N2 was introduced into the adsorbent bed, and the N2 flow rate and heating temperature were controlled to maintain the N2 temperature at the outlet of the regeneration reactor above 240°C for 2 hours. After regeneration was completed, heating was stopped, and N2 was continuously introduced until the temperature dropped to room temperature to obtain the regenerated adsorbent. The N2 was then switched to a mixed gas for adsorption experiments. This adsorption-desorption process was repeated multiple times to examine the cyclic regeneration performance of the adsorbent.

[0125] The regenerated adsorbent was subjected to multiple experiments using a "reaction-regeneration-reaction-regeneration" method, and its activity and radial compressive strength were tested. The results are shown in Table 6.

[0126] Table 6. Results of Catalyst Sample Regeneration Activity Evaluation Tests

[0127] Number of regenerations 100 200 300 400 500 Initial adsorption capacity / % 6.89 6.89 6.89 6.89 6.89 <![CDATA[Raw gas concentration CO2 / ppm]]> 1523 1578 1469 1486 1542 <![CDATA[CO2 content at the outlet / ppm]]> ＜0.1 ＜0.1 ＜0.1 ＜0.1 ＜0.1 Regeneration adsorption capacity / % 6.82 6.67 6.54 6.03 5.56 Adsorption retention rate / % 98.8 96.8 95 87.5 80.8 Radial compressive strength / N / particle 82.1 75.8 72.3 67.8 60.8

[0128] The experimental results above show that when the number of regenerations is less than 300, the adsorption performance and mechanical properties of the adsorbent remain basically stable, with an adsorption capacity greater than 6.54%, an adsorption retention rate greater than 95%, and a radial compressive strength greater than 72.3 N / particle. When the number of regenerations is greater than 300, the adsorption capacity, adsorption retention rate, and radial compressive strength decrease simultaneously. When the number of regenerations is 500, the adsorption performance decreases by about 20%. According to the technical performance parameters, the adsorbent meets the index requirements in Table 1. The accuracy and adsorption capacity of the adsorbent can also meet the current industry technical requirements, indicating that the carbon dioxide adsorbent provided in this application embodiment can be regenerated more than 500 times.

[0129] Therefore, the carbon dioxide adsorbent provided in this application embodiment exhibits excellent CO2 adsorption performance and stable regeneration performance. It can be recycled multiple times, has a long service life, improves resource utilization, and maintains good mechanical properties, ensuring that the adsorbent does not break during repeated regeneration and is not prone to generating dust that contaminates downstream materials, enabling the adsorbent device to operate stably for a long period of time.

[0130] Furthermore, the carbon dioxide adsorbent regeneration method provided in this application embodiment is simple, has a fast desorption speed, low desorption energy consumption, is non-corrosive to equipment, and can avoid environmental pollution, thus having higher ecological and economic benefits.

[0131] The above description is merely a preferred embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application.

Claims

1. A method for preparing a carbon dioxide adsorbent, wherein the carbon dioxide adsorbent is used to adsorb carbon dioxide from hydrocarbon materials, the preparation method comprising: Microspheres formed from alkali metal or alkaline earth metal solutions, pseudoboehmite, and silica were prepared. The microspheres are loaded with organic amines and / or subjected to a first calcination, wherein the atmosphere of the first calcination is ammonia, the temperature is 600~800℃, and the time is 2~3h; The preparation of microspheres formed from alkali metal or alkaline earth metal solutions, pseudoboehmite, and silica includes: Weigh 200g of boehmite and 56g of silica and mechanically mix them. Part of the mixture is then placed in a ball rolling machine for later use. Weigh out 0.1 mol of sodium nitrate and 0.2 mol of potassium nitrate, dissolve them in deionized water to prepare solution A, and pour it into a spray bottle for later use; Start the ball rolling machine and spray solution A evenly onto the mixed powder to obtain mother balls of 1-2 mm. Then, perform constant temperature curing at 60℃ for 12 hours. After curing, the mother ball is placed in a ball rolling machine, the remaining mixed powder is added and the ball rolling continues. Solution A is sprayed evenly to obtain microspheres with a diameter of 2-4 mm. Then, the microspheres are cured at 70℃ for 10 hours and then baked at 200℃ for 2 hours.

2. The preparation method according to claim 1, wherein, The step of loading organic amines onto the microspheres includes: The microspheres are subjected to a second calcination, wherein the atmosphere of the second calcination is air, the temperature is 500~900℃, and the time is 2~3h; An organic amine solution was loaded onto the microspheres; Drying, wherein the drying temperature is 80~120℃ and the drying time is 4~12h.

3. The preparation method according to claim 1 or 2, wherein, The organic amine is selected from at least one of diethylenetriamine, triethylenetetramine, tetraethylenepentamine, polyethyleneimine, and ethanolamine, and the dispersant for the organic amine is selected from at least one of water, methanol, ethanol, ethylene glycol, and glycerol.

4. The preparation method according to claim 1, wherein the silica has a mesoporous channel distribution, a specific surface area of ​​700~1100 m² / g, a pore volume of 0.6~2.2 mL / g, and an average mesopore diameter of 2~25 nm.

5. The carbon dioxide adsorbent prepared by any one of the preparation methods described in claims 1 to 4.

6. The application of the carbon dioxide adsorbent prepared by any one of claims 1 to 4 in the adsorption of carbon dioxide from hydrocarbon materials.

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