Application of aluminum oxide-based catalyst in regeneration of carbon dioxide-rich amine solution

Abstract

The invention belongs to the technical field of carbon dioxide capture, and particularly relates to application of an aluminum oxide-based catalyst in regeneration of a carbon dioxide-rich amine solution. The invention provides an application of an aluminum oxide-based catalyst in regeneration of a carbon dioxide-rich amine solution. Active components of the aluminum oxide-based catalyst comprise an aluminum oxide matrix and a transition metal oxide embedded in the aluminum oxide matrix. The aluminum oxide-based catalyst is used for catalytic regeneration of carbon dioxide in the carbon dioxide-rich amine solution, so that the regeneration temperature can be reduced, the regeneration efficiency can be improved, the regeneration energy consumption is reduced, the cost of capturing carbon dioxide by the organic amine solution is reduced, and the purposes of energy conservation and emission reduction are achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of carbon dioxide capture, and in particular relates to the application of an aluminum oxide-based catalyst in the regeneration of a carbon dioxide-rich amine solution. Background Art

[0002] Excessive carbon dioxide emissions can lead to severe climate change, ocean acidification, and global temperature rise. Carbon dioxide capture and storage (CCS) technology is considered a key strategic measure for controlling CO2 emissions and achieving carbon neutrality. Chemical absorption is currently the predominant flue gas carbon capture method. To ensure the absorbent's absorption rate and capacity for CO2, existing absorbents are mostly based on primary / secondary and tertiary amines. However, due to the strong bonding between the absorbent and CO2, the absorbent must be regenerated at high temperatures (greater than 100°C) to achieve regeneration and recycling. High-temperature regeneration is not only energy-intensive (the cost of carbon capture exceeds 350 yuan per ton of CO2), but also prone to amine degradation, ammonia slip, and corrosion of regeneration equipment due to the high-temperature alkaline environment. To improve regeneration efficiency, a catalyst is added during the regeneration process. Existing catalytic amine liquid regeneration primarily utilizes the surface active sites of solid acid catalysts to rapidly induce the decomposition of carbamates, thereby accelerating the CO2 release rate and improving regeneration efficiency. Under the conditions of achieving the same degree of regeneration, solid acid catalysts can reduce the regeneration time and required temperature, which is beneficial to reducing sensible heat, vaporization heat and regeneration tower operating pressure, and can make full use of low-grade steam as a regeneration energy source, thereby significantly reducing the investment and operating costs of carbon capture equipment.

[0003] Existing catalysts used for catalytic amine regeneration primarily include molecular sieve-supported catalysts, metal oxide-supported SBA-15 solid acid catalysts, and metal-organic framework-supported transition metal catalysts. However, the catalytically active components in these catalysts exhibit weak interactions with the matrix, making them susceptible to loss during the catalytic reaction, leading to structural damage and deactivation, which compromises the catalytic effect. Therefore, developing a catalyst with excellent activity and stability in high-temperature alkaline environments is a key task in improving carbon capture efficiency and reducing production costs. Summary of the Invention

[0004] In view of this, the present invention provides an application of an aluminum oxide-based catalyst in the regeneration of a carbon dioxide-rich amine solution. The present invention utilizes an aluminum oxide-based catalyst to catalytically regenerate carbon dioxide from a carbon dioxide-rich amine solution, which can achieve efficient regeneration of the amine solution at a relatively low temperature (below 100°C), and the catalyst has a stable structure and can be recycled.

[0005] In order to solve the above technical problems, the present invention provides an application of an alumina-based catalyst in the regeneration of a carbon dioxide-rich amine solution, wherein the active components of the alumina-based catalyst include an alumina matrix and a transition metal oxide embedded in the alumina matrix.

[0006] Preferably, the mass percentage of the transition metal element in the alumina-based catalyst is 0.21 to 0.44%;

[0007] The alumina-based catalyst includes an alumina-based powder catalyst or an alumina-based shaped catalyst; the alumina-based shaped catalyst is obtained by further shaping the alumina-based powder catalyst;

[0008] The aluminum oxide-based shaped catalyst is in the shape of a sphere or a cylinder, and the diameter of the cylinder is 3 to 5 mm and the height is 3 to 5 cm;

[0009] The specific surface area of ​​the aluminum oxide-based shaped catalyst is 150 to 200 m 2 / g, pore volume is 0.4~0.7m 3 / g, mechanical strength is 80~130N / mm 2 .

[0010] Preferably, the preparation method of the aluminum oxide-based powder catalyst comprises the following steps:

[0011] The inorganic aluminum salt, sucrose, transition metal salt and water are mixed, the pH value is adjusted to 6.8 to 7.2, and the mixture is concentrated and degassed to obtain a gel;

[0012] Separating the gel into solid and liquid, and sequentially performing a first drying and a first calcination on the solid obtained by the solid-liquid separation to obtain an aluminum oxide-based powder catalyst;

[0013] The preparation method of the aluminum oxide-based shaped catalyst comprises the following steps:

[0014] The aluminum oxide-based powder catalyst, a binder, a peptizing agent, a lubricant, a pore-forming agent, a structural aid and water are mixed and then extruded into a mold. The molded green body is sequentially subjected to a second drying and a second calcination to obtain the aluminum oxide-based molded catalyst.

[0015] Preferably, the inorganic aluminum salt includes aluminum nitrate, aluminum chloride or aluminum sulfate; the transition metal salt includes transition metal nitrate, transition metal sulfate, transition metal acetate or transition metal chloride; the transition metal includes one or more of cobalt, zirconium, manganese, cobalt, nickel and cerium;

[0016] The molar ratio of the inorganic aluminum salt to sucrose is 1 to 1.3:1;

[0017] The molar ratio of the inorganic aluminum salt to the transition metal salt is 336-1353:1.

[0018] Preferably, the pH regulator for adjusting the pH value includes ammonia water or sodium hydroxide solution;

[0019] The concentration and degassing are carried out under stirring conditions, the stirring temperature is 60-80° C., and the stirring time is 2-12 hours.

[0020] Preferably, the first drying temperature is 60-100°C and the time is 2-4 hours;

[0021] The temperature of the first calcination is 500-550° C., and the holding time is 4-6 hours; the heating rate for heating to the temperature required for the first calcination is 4.5-5.5° C. / min.

[0022] Preferably, the mixing of the aluminum oxide-based powder catalyst, binder, peptizing agent, lubricant, pore former, structural additive and water comprises the following steps:

[0023] Firstly, an aluminum oxide-based powder catalyst, a binder, a peptizing agent, a lubricant, a pore former and a structural additive are mixed to obtain a dry material;

[0024] mixing the dry materials and water for a second time;

[0025] The binder is one or more of pseudo-boehmite, silica sol, kaolin, hydrotalcite, cellulose, starch and polyvinyl alcohol;

[0026] The peptizing agent is one or more of nitric acid, hydrochloric acid, acetic acid and citric acid;

[0027] The lubricant is glycerin;

[0028] The pore-forming agent is one or more of starch, activated carbon, sesbania powder, polyethylene glycol and methyl cellulose;

[0029] The structural additive is one or more of glass fiber, carbon fiber, graphite fiber, whisker, quartz fiber and ceramic fiber.

[0030] Preferably, the mass percentage of the aluminum oxide-based powder catalyst in the dry material is 40 to 75%;

[0031] The binder accounts for 8 to 15% of the dry material by mass;

[0032] The mass percentage of the peptizing agent in the dry material is 6 to 8%;

[0033] The mass percentage of the lubricant in the dry material is 7 to 12%;

[0034] The mass percentage of the pore-forming agent in the dry material is 8 to 10%;

[0035] The mass percentage of the structural additive in the dry material is 8 to 15%;

[0036] The mass ratio of the water to the dry material is 0.9 to 1.2:1.

[0037] Preferably, before the extrusion molding, the process further comprises: aging the mixed material, wherein the aging temperature is 15 to 25° C., and the aging time is 18 to 24 hours.

[0038] Preferably, the second drying temperature is 110-120°C and the time is 2-4 hours;

[0039] The temperature of the second calcination is 500-550° C., and the holding time is 4-6 hours.

[0040] The present invention provides an application of an aluminum oxide-based catalyst in the regeneration of a carbon dioxide-rich amine solution, wherein the active components of the aluminum oxide-based catalyst include an aluminum oxide matrix and a transition metal oxide embedded in the aluminum oxide matrix. The present invention utilizes an aluminum oxide-based catalyst to catalytically regenerate carbon dioxide from a carbon dioxide-rich amine solution, thereby reducing the regeneration temperature and improving the regeneration efficiency, thereby reducing the regeneration energy consumption and the cost of capturing carbon dioxide with an organic amine solution, thereby achieving the goal of energy conservation and emission reduction. At the beginning of the regeneration process, due to the high load of CO2 during the absorption process, the system tends to be acidic; if the pH value of the system is lower than pH PZC (PZC stands for point of zero charge), the surface of aluminum oxide will be positively charged (Al 3+ , Lewis acid site), as the regeneration process proceeds, the pH value of the system is greater than pH PZC Since the CO2 release system tends to be alkaline, the surface of aluminum oxide will be negatively charged (AlO2 - , Lewis base); under this alkaline condition, AlO2 is generated - As a Lewis base, it promotes the deprotonation reaction of protonated amines and converts protons (H + ) is transferred from the protonated amine to water to form H3O + ; Then, the generated H3O + It can participate in the decomposition reaction of carbamate, thereby promoting the regeneration process of amine solution. In addition, under certain conditions, the hydroxyl groups (OH - ) can interact with free CO2 to generate HCO3 - ,HCO3 -It can also participate in the regeneration process of the above-mentioned amine solution. In the present invention, aluminum oxide exhibits excellent catalytic activity, and its Lewis acid sites can further promote the decomposition reaction of carbamate, while the Lewis base sites and a small amount of HCO3 - The presence of can accelerate the deprotonation reaction of protonated amine. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is an SEM image of the aluminum oxide-based powder catalyst prepared in Example 2;

[0042] Figure 2 The XRD spectra of the powder catalysts of Examples 1 to 3 and Comparative Example 1 are shown;

[0043] Figure 3 This is a regeneration curve diagram of the aluminum oxide-based powder catalyst prepared in Examples 1 to 3 and regenerated at 102°C;

[0044] Figure 4 This is a regeneration curve diagram of the aluminum oxide-based powder catalyst prepared in Example 2 regenerated at 98°C;

[0045] Figure 5 This is a comparison diagram of the regeneration curves of the aluminum oxide-based powder catalyst prepared in Example 2 and cyclically regenerated at 98°C;

[0046] Figure 6 This is a regeneration curve of the aluminum oxide-based powder catalyst prepared in Example 2, which was regenerated at 98° C. under low CO2 loading conditions;

[0047] Figure 7 This is a comparison chart of regeneration curves of the alumina-based shaped catalyst prepared in Example 2 when regenerated at 98°C with different addition amounts. DETAILED DESCRIPTION

[0048] The present invention provides an application of an aluminum oxide-based catalyst in the regeneration of a carbon dioxide-rich amine solution. The active components of the aluminum oxide-based catalyst include an aluminum oxide matrix and a transition metal oxide embedded in the aluminum oxide matrix.

[0049] As a specific embodiment of the present invention, the mass percentage of the transition metal element in the alumina-based catalyst is 0.21-0.44%; the alumina-based catalyst may include an alumina-based powder catalyst or an alumina-based shaped catalyst; the alumina-based shaped catalyst is obtained by further shaping the alumina-based powder catalyst; the shape of the alumina-based shaped catalyst may be spherical or cylindrical, the diameter of the cylinder may be 3-5 mm, specifically 3.5 mm, 4 mm, 4.5 mm or 5 mm; the height of the cylinder may be 3-5 cm, specifically 3.5 mm, 4 mm, 4.5 mm or 5 mm. In the present invention, the alumina-based shaped catalyst with a certain shape can be directly used as filler in the packed tower.

[0050] As a specific embodiment of the present invention, the specific surface area of ​​the aluminum oxide-based shaped catalyst can be 150 to 200 m 2 / g, the pore volume of the aluminum oxide-based shaped catalyst can be 0.4 to 0.7 m 3 / g, the mechanical strength of the aluminum oxide-based shaped catalyst can be 80-130N / mm 2 .

[0051] In the present invention, the alumina-based shaped catalyst has good activity and can be used as a monolithic filler in an existing CO2 capture device, thereby reducing the regeneration temperature and effectively alleviating the problems of thermal degradation loss of the regenerated collector and equipment corrosion.

[0052] As a specific embodiment of the present invention, the preparation method of the aluminum oxide-based powder catalyst may include the following steps:

[0053] The inorganic aluminum salt, sucrose, transition metal salt and water are mixed, the pH value is adjusted to 6.8 to 7.2, and the mixture is concentrated and degassed to obtain a gel;

[0054] The gel is separated into solid and liquid, and the solid obtained by the solid-liquid separation is sequentially subjected to a first drying and a first calcination to obtain an aluminum oxide-based powder catalyst.

[0055] The present invention comprises mixing an inorganic aluminum salt, sucrose, a transition metal salt, and water, adjusting the pH to 6.8-7.2, concentrating, and degassing to obtain a gel. In a specific embodiment of the present invention, the inorganic aluminum salt may include aluminum nitrate, aluminum chloride, or aluminum sulfate, and the aluminum nitrate may be aluminum nitrate nonahydrate; the transition metal salt may include a transition metal nitrate, a transition metal sulfate, a transition metal acetate, or a transition metal chloride; the transition metal may include one or more of cobalt, zirconium, manganese, cobalt, nickel, and cerium, and may also be one of these, more specifically cobalt; and the transition metal salt may be cobalt nitrate hexahydrate. In a specific embodiment of the present invention, the molar ratio of the inorganic aluminum salt to sucrose may be 1-1.3:1, specifically 1:1, 1:1.1, 1:1.2, or 1:1.3; and the molar ratio of the inorganic aluminum salt to the transition metal salt may be 336-1353:1, specifically 1353:1, 676:1, or 336:1. As a specific embodiment of the present invention, the water can be deionized water. The present invention has no special limitation on the amount of the water as long as it can be completely dissolved.

[0056] As a specific embodiment of the present invention, the mixing can be performed under stirring. As a specific embodiment of the present invention, the pH adjuster for adjusting the pH value can include ammonia water or sodium hydroxide solution, specifically ammonia water; the adjusted pH value can be specifically 7. As a specific embodiment of the present invention, the pH value can be adjusted with stirring, and the stirring time can be 0.8 to 1.2 hours, specifically 1 hour. During the mixing process, the present invention utilizes hydration between inorganic aluminum salts and water, where the hydroxyl groups of sucrose react with aluminum ions to form a macromolecular network structure, thereby accelerating the transformation of sol into gel. The present invention uses ammonia water (alkaline solution) as a precipitant to prepare hydrated aluminum oxide, known as pseudo-boehmite. Pseudo-boehmite (AlOOH·nH2O, n is 0.08 to 0.62) generally converts to γ-Al2O3 upon dehydration by heating above 450°C (at 200°C, pseudo-boehmite converts to boehmite; at 450°C, boehmite converts to γ-Al2O3).

[0057] As a specific embodiment of the present invention, the concentration and degassing can be carried out under stirring conditions. The stirring temperature can be 60-80°C, specifically 60°C, 65°C, 70°C, 75°C or 80°C; the stirring time can be 2-12 hours, specifically 3 hours, 5 hours, 7 hours, 9 hours or 11 hours. The present invention gradually evaporates the solvent in the sol through heating and stirring, thereby increasing the sol concentration and facilitating the subsequent gelation process. During the heating and stirring process, the gas in the sol (such as dissolved air or other volatile components) is released, avoiding the formation of bubbles during the gelation process or affecting the uniformity of the final material.

[0058] After obtaining the gel, the present invention separates the gel into solid and liquid, and sequentially performs a first drying and a first calcination on the solid obtained by the solid-liquid separation to obtain an alumina-based powder catalyst. As a specific embodiment of the present invention, the solid-liquid separation method can be centrifugation; the solid obtained by the solid-liquid separation is a powder. As a specific embodiment of the present invention, the temperature of the first drying can be 60-100°C, specifically 60°C, 70°C, 80°C, 90°C, or 100°C; the time of the first drying can be 2-4 hours, specifically 2.5 hours, 3 hours, or 3.5 hours; the temperature of the first calcination can be 500-550°C, specifically 510°C, 520°C, 530°C, or 540°C; the holding time of the first calcination can be 4-6 hours, specifically 4.5 hours, 5 hours, or 5.5 hours; the heating rate to the required temperature for the first calcination can be 4.5-5.5°C / min, specifically 4.8°C / min, 5°C / min, or 5.2°C / min. The present invention can pyrolyze sucrose to generate char through the first calcination. The char can serve as a template or skeleton for porous alumina. By releasing carbon dioxide gas, the specific surface area and pore structure of the porous alumina can be regulated. Simultaneously, the first calcination converts the transition metal salt into a transition metal oxide.

[0059] As a specific embodiment of the present invention, the preparation method of the alumina-based shaped catalyst may include the following steps:

[0060] The aluminum oxide-based powder catalyst, a binder, a peptizing agent, a lubricant, a pore-forming agent, a structural aid and water are mixed and then extruded into a mold. The molded green body is sequentially subjected to a second drying and a second calcination to obtain the aluminum oxide-based molded catalyst.

[0061] As a specific embodiment of the present invention, mixing the aluminum oxide-based powder catalyst, binder, peptizing agent, lubricant, pore former, structural additive and water may include the following steps:

[0062] Firstly, an aluminum oxide-based powder catalyst, a binder, a peptizing agent, a lubricant, a pore former and a structural additive are mixed to obtain a dry material;

[0063] The dry materials and water are mixed a second time.

[0064] As a specific embodiment of the present invention, the mass percentage of the aluminum oxide-based powder catalyst in the dry material can be 40-75%, and can be specifically 45%, 50%, 55%, 60%, 65% or 70%.

[0065] In a specific embodiment of the present invention, the binder can be one or more of pseudo-boehmite, silica sol, kaolin, hydrotalcite, cellulose, starch, and polyvinyl alcohol, specifically one of these, and more specifically pseudo-boehmite. The binder can comprise 8-15% by weight of the dry material, specifically 10%, 12%, or 14%. In the present invention, the binder primarily bonds the active components of the catalyst together, forming catalyst particles with a certain strength and shape. It enhances the mechanical strength of the catalyst and prevents particle breakage during use, thereby ensuring the long-term stability and activity of the catalyst.

[0066] As a specific embodiment of the present invention, the peptizing agent can be one or more of nitric acid, hydrochloric acid, acetic acid, and citric acid, specifically one of nitric acid, hydrochloric acid, acetic acid, and citric acid, and more specifically nitric acid; the mass concentration of the peptizing agent can be 8-12%, specifically 9%, 10%, or 11%; the mass percentage of the peptizing agent in the dry material can be 6-8%, specifically 6.5%, 7%, or 7.5%. In the present invention, the peptizing agent is used together with the binder to bond the materials by forming a sol, etc. This can improve the molding properties of the catalyst, making the catalyst easier to handle during the molding process, and also helps to improve the physical properties of the catalyst.

[0067] In one embodiment of the present invention, the lubricant may be glycerol; its mass percentage of the dry material may be 7-12%, specifically 8%, 9%, 10%, or 11%. In the present invention, the lubricant reduces friction during the catalyst molding process and facilitates demolding. It facilitates pressure transfer within the powder layer, preventing material from "holding the rod" and enabling continuous extrusion, thereby improving production efficiency and catalyst quality.

[0068] In a specific embodiment of the present invention, the pore-forming agent can be one or more of starch, activated carbon, sesbania powder, polyethylene glycol, and methylcellulose, and can specifically be one of starch, activated carbon, sesbania powder, polyethylene glycol, and methylcellulose, and can further be sesbania powder. The mass percentage of the pore-forming agent in the dry material can be 8-10%, and can specifically be 8.5%, 9%, or 9.5%. In the present invention, the pore-forming agent is primarily used to increase the specific surface area and pore structure of the catalyst, thereby improving the activity of the catalyst.

[0069] As a specific embodiment of the present invention, the structural additive can be one or more of glass fiber, carbon fiber, graphite fiber, whisker, quartz fiber, and ceramic fiber, specifically one of glass fiber, carbon fiber, graphite fiber, whisker, quartz fiber, and ceramic fiber, and more specifically glass fiber; the weight percentage of the structural additive in the dry material can be 8-15%, specifically 9%, 10%, 11%, 12%, 13%, or 14%. In the present invention, the structural additive is mainly used to improve the structural stability of the catalyst, enhance the thermal stability and mechanical strength of the catalyst, increase the specific surface area, improve the thermal stability of the catalyst and the structural stability of the main active component, thereby enhancing the durability and service life of the catalyst.

[0070] As a specific embodiment of the present invention, the mass ratio of the aluminum oxide-based powder catalyst, the binder, the peptizing agent, the lubricant, the pore former and the structural additive in the dry material can be specifically 55:10:8:9:8:10.

[0071] As a specific embodiment of the present invention, the mass ratio of water to dry material can be 0.9 to 1.2:1, and can be specifically 1:1 or 1.1:1.

[0072] As a specific embodiment of the present invention, the mixing of the aluminum oxide-based powder catalyst, binder, peptizing agent, lubricant, pore-forming agent, structural additive and water can be carried out under stirring conditions, and the stirring time can be 3 to 6 hours, specifically 3.5 hours, 4 hours, 4.5 hours or 5 hours.

[0073] As a specific embodiment of the present invention, the extrusion molding may also include: aging the mixed material, the aging temperature may be 15 to 25°C, specifically 18°C, 20°C or 23°C; the aging time may be 18 to 24h, specifically 19h, 20h, 21h or 22h.

[0074] As a specific embodiment of the present invention, the extrusion molding can be performed using an extruder to extrude cylindrical products. The speed of the extruder can be 40 to 60 r / min, specifically 45 r / min, 50 r / min or 55 r / min.

[0075] As a specific embodiment of the present invention, the temperature of the second drying can be 110-120°C, specifically 113°C, 115°C or 118°C; the time of the second drying can be 2-4h, specifically 2.5h, 3h or 3.5h; the temperature of the second calcination can be 500-550°C, specifically 510°C, 520°C, 530°C or 540°C; the holding time of the second calcination can be 4-6h, specifically 4.5h, 5h or 5.5h.

[0076] As a specific embodiment of the present invention, when the carbon dioxide-rich amine solution is catalytically regenerated using an aluminum oxide-based powder catalyst, the amount of the aluminum oxide-based powder catalyst added to the carbon dioxide-rich amine solution can be 0.2-0.3%, specifically 0.2%, 0.25% or 0.3%; when the carbon dioxide-rich amine solution is catalytically regenerated using an aluminum oxide-based shaped catalyst, the amount of the aluminum oxide-based shaped catalyst added to the carbon dioxide-rich amine solution can be 1-5%, specifically 1%, 2% or 5%.

[0077] The present invention embeds transition metals on the surface and / or within alumina, dispersing active sites. Furthermore, the present invention utilizes an alkaline co-precipitation method to combine the transition metals and alumina. Compared to supported catalysts prepared using acid etching, the present invention exhibits higher reactivity and stability (the transition metals are firmly embedded in the alumina). The metal leaching rate after eight regeneration cycles was 0.0001 wt.%, and the catalytic performance was stable. The preparation method of the alumina-based shaped catalyst is simple and easy, and the raw materials are readily available, making it suitable for mass production.

[0078] In order to further illustrate the present invention, the technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0079] Example 1

[0080] 17.26 g (0.046 mol) of aluminum nitrate nonahydrate, 13.69 g (0.04 mol) of sucrose, and 0.01 g (0.034 mmol) of cobalt nitrate hexahydrate were dissolved in 200 mL of deionized water under stirring, 25% ammonia water was added, stirred for 1 h, the pH value was adjusted to 7, and then stirred at 70° C. for 10 h to obtain a gel;

[0081] The gel was centrifuged to collect the powder, which was dried at 60°C for 3 h. The temperature was then increased to 550°C at a heating rate of 5°C / min and kept in air for 5 h for the first calcination to obtain a cobalt-doped alumina-based powder catalyst, designated as f-Al2O3-Co-1.

[0082] An alumina-based powder catalyst, pseudo-boehmite (binder), nitric acid (peptizing agent) with a mass concentration of 10%, glycerol (lubricant), sesbania powder (pore-forming agent) and glass fiber (structural additive) are mixed in a mass ratio of 55:10:8:9:8:10 to obtain a dry material. The dry material and water are stirred in a mass ratio of 1:0.9 for 4 hours, aged at 25°C for 20 hours and stirred evenly to form a sticky mass. The sticky mass is then added to the feeding trough of an extruder and extruded at a speed of 50 r / min to obtain a strip product. After drying at 120°C for 3 hours, it is calcined at 500°C for a second time for 5 hours. The calcined product is cut into a cylindrical alumina-based catalyst with a diameter of 4 mm and a length of 4 cm and is recorded as c-Al2O3-Co-1.

[0083] Example 2

[0084] An aluminum oxide-based powder catalyst was prepared according to the method of Example 1, except that the amount of cobalt nitrate hexahydrate used was 0.02 g (0.068 mmol). The prepared powder catalyst was recorded as f-Al2O3-Co-2;

[0085] An alumina-based shaped catalyst was prepared according to the method of Example 1, except that the powder catalyst (f-Al2O3-Co-2) prepared in Example 2 was used as raw material, and the prepared shaped catalyst was recorded as c-Al2O3-Co-2.

[0086] Example 3

[0087] An aluminum oxide-based powder catalyst was prepared according to the method of Example 1, except that the amount of cobalt nitrate hexahydrate used was 0.04 g (0.137 mmol). The prepared powder catalyst was recorded as f-Al2O3-Co-3;

[0088] An alumina-based shaped catalyst was prepared according to the method of Example 1, except that the powder catalyst (f-Al2O3-Co-3) prepared in Example 3 was used as raw material, and the prepared shaped catalyst was recorded as c-Al2O3-Co-3.

[0089] Comparative Example 1

[0090] Taking aluminum oxide powder catalyst as a comparative example, the specific preparation method includes the following steps:

[0091] 17.26 g (0.046 mol) of aluminum nitrate nonahydrate and 13.69 g (0.04 mol) of sucrose were dissolved in 200 mL of deionized water under stirring, 25% ammonia water was added, stirred for 1 h, the pH value was adjusted to 7, and then stirred at 70°C for 10 h to obtain a gel;

[0092] The gel was centrifuged to collect the powder, which was dried at 60°C for 3 h, and then heated to 550°C at a heating rate of 5°C / min and kept in an air atmosphere for 5 h for the first calcination to obtain an aluminum oxide powder catalyst, which was recorded as f-Al2O3-0.

[0093] The elemental compositions of the catalysts of Examples 1 to 3 and Comparative Example 1 were determined by X-ray photoelectron spectroscopy (XPS), and the results are listed in Table 1.

[0094] Table 1 Elemental composition of the powder catalysts of Examples 1 to 3 and Comparative Example 1

[0095]

[0096] The f-Al2O3-Co-2 prepared in Example 2 was examined by scanning electron microscopy to obtain a SEM image, as shown in FIG. Figure 1 As shown. Figure 1 It can be seen that the sample morphology of the alumina-based catalyst prepared by the present invention is irregular block-shaped with irregular connected pores on the surface, which is related to the carbonization of sucrose to generate a large amount of carbon dioxide gas, making the catalyst have advantages such as better specific surface area and pore volume.

[0097] The powder catalysts of Examples 1 to 3 and Comparative Example 1 were subjected to XRD detection to obtain XRD spectra, as shown in FIG. Figure 2 As shown. Figure 2 It can be seen that the Al2O3 catalyst and the Al2O3-based catalysts with different cobalt doping amounts are all amorphous, and 46° and 66° are the characteristic diffraction peaks of γ-Al2O3, corresponding to the crystal planes (400) and (440), respectively.

[0098] The CO2 catalytic regeneration performance of the catalysts of Examples 1 to 3 and Comparative Example 1 was tested according to the following method:

[0099] Detection method 1: CO2 and N2 are introduced into a three-necked flask containing 200 mL of a composite amine solution at a volume ratio of 12:88 to prepare an amine solution with a CO2 absorption load of 2.6 mol CO2 / L. The aluminum oxide-based powder catalyst prepared in Examples 1 to 3 is added (the amount of the powder catalyst added is 0.25% by mass of the amine solution) and the amine solution is heated to 102°C for regeneration. The released CO2 flow rate is monitored by a mass flow meter. The results are as follows: Figure 3 shown.

[0100] Depend on Figure 3 It can be seen that the catalyst provided by the present invention has a good catalytic effect on carbon dioxide regeneration, among which f-Al2O3-Co-2 has the best catalytic effect, and the CO2 loading amount in 2000s is reduced by 0.42 mol CO2 / L compared with the blank condition.

[0101] Detection method 2: The aluminum oxide-based powder catalyst (f-Al2O3-Co-2) prepared in Example 2 was tested according to the method of detection method 1, except that the temperature of the heated amine solution was adjusted from 102°C to 98°C, and the flow rate of CO2 released by regeneration was monitored by a mass flow meter. The results are as follows: Figure 4 shown.

[0102] Depend on Figure 4 It can be seen that the catalyst provided by the present invention can reduce the CO2 loading in 2000s by 0.38 mol CO2 / L as compared with the blank condition, and successfully reduce the regeneration temperature to below 100°C.

[0103] Detection method 3: The alumina-based powder catalyst (f-Al2O3-Co-2) prepared in Example 2 was subjected to a cyclic regeneration performance test. The specific method is as described in Detection Method 2. The amine solution was heated to 98°C, and the flow rate of CO2 released by regeneration was monitored by a mass flow meter. The first test was the original data, the second test result was the first cycle data, and so on. The ninth test result was the eighth cycle data result. After each experiment, the amine solution and the catalyst were allowed to stand at room temperature. After cooling, they were washed three times with deionized water at 8000r / min, washed once with ethanol, dried at 60°C for 12h, and weighed. Then, a fresh catalyst (alumina-based powder catalyst, f-Al2O3-Co-2) of the same mass as the catalyst after drying in the eighth cycle test was used for regeneration test under the same CO2-loaded amine solution. The test results are as follows. Figure 5 shown.

[0104] Depend on Figure 5 It can be seen that after the eighth cycle, the CO2 loading in 2000s decreased by 0.02 molCO2 / L compared with the original data, which proves that the catalyst effect is stable and the active sites are not easily lost.

[0105] Detection method 4: Simulate the low-load working condition of CO2 in the real analytical tower to detect the catalytic regeneration performance of the alumina-based powder catalyst (f-Al2O3-Co-2) prepared in Example 2. First, CO2 and N2 are introduced into a three-necked flask containing 200mL of a composite amine solution at a volume ratio of 12:88 to prepare an absorption-saturated amine solution. Regenerate at 90°C for 2h to prepare a low-load 1.4mol CO2 / L amine solution, cool to room temperature for use. Then, heat the standby amine solution to 98°C, and monitor the flow rate of CO2 released by regeneration with a mass flow meter. The results are as follows: Figure 6 shown.

[0106] Depend on Figure 6It can be seen that the catalyst provided by the present invention can reduce the low CO2 loading amount in 2000s by 0.2 mol CO2 / L compared with the blank condition to the maximum extent, indicating that the catalyst still has significant activity at low loading and the effect is stable.

[0107] Detection method 5: CO2 and N2 were introduced into a three-necked flask containing 200 mL of a composite amine solution in a volume ratio of 12:88 to prepare an absorption-saturated amine solution. The aluminum oxide-based shaped catalyst (c-Al2O3-Co-2) prepared in Example 2 was added thereto (the amount of the shaped catalyst added was 1%, 2%, and 5% by mass of the amine solution, respectively). The amine solution was heated to 98°C for regeneration. The released CO2 flow rate was monitored using a mass flow meter. The results were as follows: Figure 7 shown.

[0108] Depend on Figure 7 It can be seen that the molded catalyst of the present invention can effectively reduce the CO2 load of the complex amine when the mass addition amount is 1wt%, 2wt% and 5wt%. Among them, when the mass addition amount is 5wt%, the low CO2 load of 2000s can be reduced by 0.26mol CO2 / L compared with the non-catalytic condition. The molded catalyst successfully reduces the regeneration temperature to below 100°C.

[0109] Although the above embodiment provides a detailed description of the present invention, it is only a part of the embodiments of the present invention, not all of the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the scope of protection of the present invention.

Claims

1. An application of an aluminum oxide-based catalyst in the regeneration of a carbon dioxide-rich amine solution, characterized in that: The active components of the alumina-based catalyst include an alumina matrix and a transition metal oxide embedded in the alumina matrix.

2. The application according to claim 1, characterized in that The mass percentage of the transition metal element in the alumina-based catalyst is 0.21 to 0.44%; The alumina-based catalyst includes an alumina-based powder catalyst or an alumina-based shaped catalyst; the alumina-based shaped catalyst is obtained by further shaping the alumina-based powder catalyst; The aluminum oxide-based shaped catalyst is in the shape of a sphere or a cylinder, and the diameter of the cylinder is 3 to 5 mm and the height is 3 to 5 cm; The specific surface area of ​​the aluminum oxide-based shaped catalyst is 150 to 200 m 2 / g, pore volume is 0.4~0.7m 3 / g, mechanical strength is 80~130N / mm 2 .

3. The use according to claim 1 or 2, characterized in that: The preparation method of the aluminum oxide-based powder catalyst comprises the following steps: The inorganic aluminum salt, sucrose, transition metal salt and water are mixed, the pH value is adjusted to 6.8 to 7.2, and the mixture is concentrated and degassed to obtain a gel; Separating the gel into solid and liquid, and sequentially performing a first drying and a first calcination on the solid obtained by the solid-liquid separation to obtain an aluminum oxide-based powder catalyst; The preparation method of the aluminum oxide-based shaped catalyst comprises the following steps: The aluminum oxide-based powder catalyst, a binder, a peptizing agent, a lubricant, a pore-forming agent, a structural aid and water are mixed and then extruded into a mold. The molded green body is sequentially subjected to a second drying and a second calcination to obtain the aluminum oxide-based molded catalyst.

4. The application according to claim 3, characterized in that The inorganic aluminum salt includes aluminum nitrate, aluminum chloride or aluminum sulfate; the transition metal salt includes transition metal nitrate, transition metal sulfate, transition metal acetate or transition metal chloride; the transition metal includes one or more of cobalt, zirconium, manganese, cobalt, nickel and cerium; The molar ratio of the inorganic aluminum salt to sucrose is 1 to 1.3:1; The molar ratio of the inorganic aluminum salt to the transition metal salt is 336-1353:

1.

5. The application according to claim 3, characterized in that: The pH regulator for adjusting the pH value includes ammonia water or sodium hydroxide solution; The concentration and degassing are carried out under stirring conditions, the stirring temperature is 60-80° C., and the stirring time is 2-12 hours.

6. The application according to claim 3, characterized in that: The first drying temperature is 60-100° C. and the time is 2-4 hours; The temperature of the first calcination is 500-550° C., and the holding time is 4-6 hours; the heating rate for heating to the temperature required for the first calcination is 4.5-5.5° C. / min.

7. The use according to claim 3, characterized in that: The mixing of the aluminum oxide-based powder catalyst, binder, peptizing agent, lubricant, pore former, structural additive and water comprises the following steps: Firstly, an aluminum oxide-based powder catalyst, a binder, a peptizing agent, a lubricant, a pore former and a structural additive are mixed to obtain a dry material; mixing the dry materials and water for a second time; The binder is one or more of pseudo-boehmite, silica sol, kaolin, hydrotalcite, cellulose, starch and polyvinyl alcohol; The peptizing agent is one or more of nitric acid, hydrochloric acid, acetic acid and citric acid; The lubricant is glycerin; The pore-forming agent is one or more of starch, activated carbon, sesbania powder, polyethylene glycol and methyl cellulose; The structural additive is one or more of glass fiber, carbon fiber, graphite fiber, whisker, quartz fiber and ceramic fiber.

8. The application according to claim 7, characterized in that: The mass percentage of the aluminum oxide-based powder catalyst in the dry material is 40-75%; The binder accounts for 8 to 15% of the dry material by mass; The mass percentage of the peptizing agent in the dry material is 6 to 8%; The mass percentage of the lubricant in the dry material is 7 to 12%; The mass percentage of the pore-forming agent in the dry material is 8 to 10%; The mass percentage of the structural additive in the dry material is 8 to 15%; The mass ratio of the water to the dry material is 0.9 to 1.2:

1.

9. The application according to claim 3, characterized in that: Before the extrusion molding, the mixed material is aged, the aging temperature is 15 to 25° C., and the aging time is 18 to 24 hours.

10. The application according to claim 3, characterized in that: The second drying temperature is 110-120°C and the time is 2-4 hours; The temperature of the second calcination is 500-550° C., and the holding time is 4-6 hours.

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