Sulfonated bamboo charcoal-based cerium-doped catalyst as well as preparation method and application thereof

Abstract

The invention provides a sulfonated bamboo charcoal-based cerium-doped catalyst as well as a preparation method and application thereof, and relates to the technical field of carbon dioxide desorption. The preparation method comprises the following steps: mixing bamboo charcoal, cerium oxide and concentrated sulfuric acid for sulfonation reaction to obtain a sulfonated product; and carrying out anaerobic calcination on the sulfonated product to obtain the sulfonated bamboo charcoal-based cerium-doped catalyst. Biomass bamboo charcoal which is high in raw material yield, low in price, renewable, rich in pore channels, large in specific surface area and has a catalytic function is selected as a substrate, and active components including sulfonic acid groups and cerium elements are loaded. Wherein the biomass bamboo charcoal provides a rich pore space for the loading of sulfonic acid groups and Ce, and is beneficial to increasing the contact area between the catalyst and a CO2 split-phase absorbent rich solution; the obtained catalyst can effectively promote proton transfer in a CO2 desorption process under the regulation and control of double acidic sites of sulfonic acid groups and Ce, and is especially suitable for an efficient desorption process of a primary-tertiary diamine carbon dioxide phase-splitting absorbent pregnant solution at a low temperature (70-120 DEG C).

Description

Technical Field

[0001] The present invention relates to the technical field of carbon dioxide desorption, and in particular to a sulfonated bamboo charcoal-based cerium-doped catalyst, a preparation method thereof, and an application thereof. Background Art

[0002] Carbon dioxide (CO2) produced by fossil fuel combustion and industrial production is the primary cause of the greenhouse effect, and its large-scale emissions have adversely impacted the global climate. Among existing carbon capture technologies, chemical absorption has attracted considerable attention due to its mature technology, high capture efficiency, high CO2 product purity, and wide applicability. However, the high desorption temperature of the amine-rich solution (greater than 120°C) in this technology consumes significant energy, and the desorption cost accounts for over 70% of the total CO2 capture cost, severely restricting its large-scale economic feasibility. In recent years, researchers have proposed the use of CO2 phase-separating absorbents, which only allow the CO2-containing rich solution to enter the desorption tower, thereby directly reducing the sensible heat of heating and latent heat of evaporation during the desorption process. However, phase-separating absorbents have not yet effectively addressed the high temperatures required for rich solution desorption. Furthermore, phase-separating absorbents generally suffer from high rich solution viscosity and high desorption energy consumption per unit volume. Therefore, lowering the desorption temperature of the phase-separating absorbent rich solution and increasing its low-temperature desorption driving force have become key challenges in reducing desorption energy consumption and promoting the industrial application of phase-separating absorbents.

[0003] Adding an appropriate amount of catalyst can increase the rate of CO2 release from the rich solution at low temperatures, thereby saving desorption energy. Existing catalysts mainly include molecular sieves, organic metal frameworks, and their derivatives. For example, studies have shown that adding appropriate amounts of HZSM-5 and Al2O3 / HZSM-5 to a 30wt% MEA (monoethanolamine) aqueous solution can reduce energy consumption by 28.5% and 34.2%, respectively. At 100°C, adding Fe3O4@UiO-66-SO4 to a 5mol / L MEA aqueous solution can reduce desorption energy consumption by 44.7%. However, most catalysts have a poor effect on promoting the desorption of rich solution from primary and tertiary diamine (compounds containing two amino groups, one primary and the other tertiary) phase-separated absorbents, and may even inhibit desorption. Summary of the Invention

[0004] In view of this, the present invention aims to provide a sulfonated bamboo charcoal-based cerium-doped catalyst, its preparation method, and its application. The sulfonated bamboo charcoal-based cerium-doped catalyst provided by the present invention is used to desorb a primary or tertiary diamine carbon dioxide phase-separation absorbent rich solution, effectively promoting proton transfer during the CO2 desorption process and achieving efficient CO2 desorption from the phase-separation absorbent rich solution.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a method for preparing a sulfonated bamboo charcoal-based cerium-doped catalyst, comprising the following steps:

[0007] The bamboo charcoal, cerium oxide and concentrated sulfuric acid are mixed to carry out a sulfonation reaction to obtain a sulfonated product;

[0008] The sulfonated product is subjected to oxygen-free calcination to obtain the sulfonated bamboo charcoal-based cerium-doped catalyst.

[0009] Preferably, the mass ratio of the bamboo charcoal to cerium oxide is 9:0.5-1.

[0010] Preferably, the mass fraction of the concentrated sulfuric acid is 98%, and the usage ratio of the bamboo charcoal to the concentrated sulfuric acid is 0.1-0.3 g:1 mL.

[0011] Preferably, the temperature of the sulfonation reaction is 90-100° C., and the time is 4-8 hours.

[0012] Preferably, the temperature of the oxygen-free calcination is 300-350° C., and the time is 4-8 hours.

[0013] Preferably, the method for preparing bamboo charcoal comprises the following steps:

[0014] mixing bamboo powder with a phosphoric acid aqueous solution for pretreatment to obtain pretreated bamboo powder;

[0015] Carbonizing the pretreated bamboo powder in an oxygen-free state to obtain the bamboo charcoal;

[0016] The mass fraction of the phosphoric acid aqueous solution is 30-50%, the usage ratio of the bamboo powder to the phosphoric acid aqueous solution is 1g:10mL; the pretreatment time is 4-8h; the temperature of the anaerobic carbonization is 300-350°C, and the time is 3-5h.

[0017] Preferably, the method for preparing cerium oxide comprises the following steps:

[0018] Ce(NO3)3 is calcined to obtain cerium oxide; the calcination temperature is 350°C, the time is 3 hours, and the calcination is carried out in an air atmosphere.

[0019] The present invention provides a sulfonated bamboo charcoal-based cerium-doped catalyst prepared by the preparation method described in the above technical solution.

[0020] The present invention provides the use of the sulfonated bamboo charcoal-based cerium-doped catalyst described in the above technical solution in the desorption of rich liquid of an organic amine carbon dioxide phase-separation absorbent, wherein the organic amine includes a primary or tertiary diamine.

[0021] The present invention provides a method for desorbing a rich solution of an organic amine carbon dioxide phase-separation absorbent, comprising the following steps:

[0022] The organic amine carbon dioxide phase separation absorbent rich liquid is mixed with a catalyst for desorption to obtain carbon dioxide; the organic amine includes primary and tertiary diamines, and the catalyst is the sulfonated bamboo charcoal-based cerium-doped catalyst described in the above technical solution; the desorption temperature is 70-120°C.

[0023] The present invention provides a method for preparing a sulfonated bamboo charcoal-based cerium-doped catalyst, comprising the following steps: mixing bamboo charcoal, cerium oxide and concentrated sulfuric acid to carry out a sulfonation reaction to obtain a sulfonated product; and calcining the sulfonated product in the absence of oxygen to obtain the sulfonated bamboo charcoal-based cerium-doped catalyst. The present invention uses biomass bamboo charcoal with high raw material output, low price, renewable nature, rich pores, large specific surface area, and catalytic function (bamboo charcoal contains functional groups such as CO and C=O) as a substrate, and loads active components such as sulfonic acid groups (-SO3H) and cerium elements (Ce). Among them, biomass bamboo charcoal provides abundant pore space for the loading of sulfonic acid groups and Ce, which is beneficial to increasing the contact area between the catalyst and the carbon dioxide phase separation absorbent rich liquid; the sulfonic acid group is beneficial to increasing the catalyst acid sites and improve its hydrophilicity; Ce can increase the Lewis acid sites of the catalyst and further enhance its electron-accepting ability; the obtained sulfonated bamboo charcoal-based cerium-doped catalyst, under the regulation of the dual acid sites of sulfonic acid groups and Ce, can effectively promote proton transfer in the CO2 desorption process, and realize the efficient desorption of CO2 in the rich liquid of the phase-separated absorbent at low temperature (70-120℃), which is particularly suitable for the desorption process of the rich liquid of primary and tertiary diamine carbon dioxide phase-separated absorbent. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The BET test results of bamboo powder, bamboo charcoal, cerium oxide and Ce@SO3H-BC in Example 1 are as follows: Figure 1 (a) is the N2 desorption / adsorption isotherm, and (b) is the pore size distribution;

[0025] Figure 2 FT-IR (Fourier transform infrared spectroscopy) characterization results of bamboo powder, bamboo charcoal, cerium oxide and 9:1Ce@SO3H-BC in Example 1;

[0026] Figure 3 The SEM and EDS scan results of the 9:1Ce@SO3H-BC catalyst in Example 1 are shown. Figure 3 (a) is the SEM image, (b) is the EDS surface scan, (c) is the EDS surface scan-C, (d) is the EDS surface scan-S, (e) is the EDS surface scan-O, and (f) is the EDS surface scan-Ce;

[0027] Figure 4 TGA-DTG curves of bamboo charcoal, CeO2 and 9:1Ce@SO3H-BC in Example 1;

[0028] Figure 5 The CO2 absorption and desorption device in the embodiment;

[0029] Figure 6 is the instantaneous desorption rate of CO2 under the action of different catalysts in the examples;

[0030] Figure 7 is the total desorption amount of CO2 under the action of different catalysts in the examples;

[0031] Figure 8 is the cumulative desorption amount of CO2 under the action of different catalysts in the examples. DETAILED DESCRIPTION

[0032] The present invention provides a method for preparing a sulfonated bamboo charcoal-based cerium-doped catalyst, comprising the following steps:

[0033] The bamboo charcoal, cerium oxide and concentrated sulfuric acid are mixed to carry out a sulfonation reaction to obtain a sulfonated product;

[0034] The sulfonated product is subjected to oxygen-free calcination to obtain the sulfonated bamboo charcoal-based cerium-doped catalyst.

[0035] In the present invention, unless otherwise specified, all raw materials involved are commercially available products well known in the art.

[0036] The invention mixes bamboo charcoal, cerium oxide and concentrated sulfuric acid to carry out sulfonation reaction to obtain a sulfonated product.

[0037] In the present invention, the method for preparing bamboo charcoal preferably comprises the following steps:

[0038] mixing bamboo powder with a phosphoric acid aqueous solution for pretreatment to obtain pretreated bamboo powder;

[0039] The pretreated bamboo powder is subjected to anaerobic carbonization to obtain the bamboo charcoal.

[0040] In the present invention, the particle size of the bamboo powder is preferably 200-400 mesh. In the present invention, the mass fraction of the phosphoric acid aqueous solution is preferably 30-50%, and can be 30%, 40%, or 50%; the ratio of the bamboo powder to the phosphoric acid aqueous solution is preferably 1g:10mL. In the present invention, the pretreatment time is preferably 4-8 hours, and can be 4, 5, 6, 7, or 8 hours, and the pretreatment can be carried out at room temperature. In the present invention, the phosphoric acid aqueous solution is preferably added to the bamboo powder and the pretreatment is carried out under stirring (the pretreatment can also be referred to as an immersion treatment). The present invention uses the phosphoric acid aqueous solution to pretreat the bamboo powder, which, on the one hand, can remove impurities in the bamboo powder; on the other hand, it promotes the separation of bamboo powder cellulose and the hydrolysis of polysaccharides. After the hydrolysis of cellulose and polysaccharides, a large number of pores will be formed, increasing the specific surface area of ​​the catalyst.

[0041] After the pretreatment, the application preferably performs solid-liquid separation and solid-phase drying on the obtained reaction solution in sequence to obtain a sulfonated product. In the application, the solid-liquid separation can be vacuum filtration to remove excess aqueous phosphoric acid; the drying can be baking, and the temperature of the baking can be 60-80℃, and the time can be 12h, and the excess water is removed by baking.

[0042] In the application, the temperature of the oxygen-free carbonization is preferably 300-350℃, which can be 300, 310, 320, 330, 340 or 350℃, the temperature rising rate from room temperature (25℃) to the temperature of the oxygen-free carbonization is preferably 10℃ / min, and the time of the oxygen-free carbonization is preferably 3-5h, which can be 3, 4 or 5h; the oxygen-free carbonization is preferably performed under nitrogen protection, and the flow rate of the nitrogen is preferably 200mL / min. In the embodiment of the application, the oxygen-free carbonization is performed in a tube furnace, specifically, the pretreated bamboo powder is placed in the tube furnace, before heating, the tube furnace is first continuously supplied with nitrogen at 25℃ for 30min to remove residual air in the furnace, and then heated to 300-350℃ at a temperature rising rate of 10℃ / min to perform the oxygen-free carbonization.

[0043] After the oxygen-free carbonization, the application preferably cools the obtained product to room temperature, and then performs washing and drying in sequence to obtain the bamboo charcoal. In the application, the washing preferably uses deionized water to repeatedly clean until the filtrate is neutral; and the temperature of the drying can be 105℃.

[0044] The bamboo charcoal prepared by the above preparation method has a large specific surface area, which is beneficial to improve the catalytic effect. The bamboo charcoal used in the application has good stability and the pore structure is not easy to be damaged.

[0045] In the application, the preparation method of the cerium oxide includes the following steps:

[0046] The Ce(NO3)3 is calcined to obtain cerium oxide; the temperature of the calcination is 350℃, and the time is 3h, and the calcination is performed in an air atmosphere.

[0047] In the application, the Ce(NO3)3 can be added in the form of Ce(NO3)3·6H2O; and the temperature rising rate from room temperature (25)℃ to the temperature of the calcination is preferably 10℃ / min. After the calcination, the obtained cerium oxide (CeO2) powder is placed in an oven at 105℃ for drying.

[0048] In the present application, the mass ratio of the bamboo charcoal to cerium oxide is preferably 9:0.5-1, and can be 9:0.5, 9:0.6, 9:0.7, 9:0.8, 9:0.9 or 9:1; the present application controls the mass ratio of the bamboo charcoal to cerium oxide in the above range, which is beneficial to improve the catalytic effect of the catalyst. In the present application, the mass fraction of the concentrated sulfuric acid is preferably 98%, and the dosage ratio of the bamboo charcoal to the concentrated sulfuric acid is preferably 0.1-0.3 g:1 mL, and can be 0.1 g:1 mL, 0.2 g:1 mL or 0.3 g:1 mL. In the present application, the mixing method of the bamboo charcoal, cerium oxide and concentrated sulfuric acid is preferably mixing the bamboo charcoal and cerium oxide, and adding concentrated sulfuric acid to the obtained mixture.

[0049] In the present application, the temperature of the sulfonation reaction is preferably 90-100℃, and can be 90℃, 95℃ or 100℃, and the time is preferably 4-8 h, and can be 4 h, 5 h, 6 h, 7 h or 8 h; the sulfonation reaction is preferably carried out under stirring, and the stirring rate is preferably 300-500 rpm. In the process of the sulfonation reaction, the bamboo charcoal has a porous structure and rich surface functional groups, which can be used as an anchoring point of the sulfonic acid group; the sulfur-oxygen free radical (-SO3 or -HSO3 + ) provided by the sulfuric acid molecule attacks the active site of the bamboo charcoal to form a covalently bonded sulfonic acid group.

[0050] After the completion of the sulfonation reaction, the present application preferably sequentially carries out water washing, filtration and drying on the obtained reaction liquid (suspension) to obtain a sulfonation product. In the present application, deionized water is preferably used for water washing; the specific operation of the water washing is preferably as follows: the reaction liquid is poured into deionized water, and wet powder is obtained through precipitation and filtration; the wet powder is repeatedly washed until the filtrate is neutral; the volume ratio of the reaction liquid to deionized water can be 1:20. In the present application, the drying can be oven drying, and the oven drying temperature can be 105℃, and the time can be 12 h.

[0051] After obtaining the sulfonation product, the present application carries out anaerobic calcination on the sulfonation product to obtain the sulfonated bamboo charcoal-based cerium-doped catalyst.

[0052] In the present application, the temperature of the oxygen-free calcination is preferably 300-350℃, and can be 310, 320, 330, 340 or 350℃, the temperature rising rate of the oxygen-free calcination is preferably 10℃ / min when the temperature rises from room temperature (25℃), the time of the oxygen-free calcination is preferably 4-8h, and can be 4, 5, 6, 7 or 8h; the oxygen-free calcination is preferably carried out under nitrogen protection. In the embodiments of the present application, the oxygen-free calcination is carried out in a tube furnace, specifically, the sulfonated product is put into the tube furnace, and before calcination, nitrogen is passed at 25℃ for 30min to remove the residual air in the tube furnace; then the temperature is raised to 300-350℃ at a temperature rising rate of 10℃ / min to carry out the oxygen-free calcination.

[0053] In the present application, the reaction process involved in the oxygen-free calcination can be: change of the bamboo charcoal carbon skeleton: the bamboo charcoal carbon skeleton is further graphitized, part of the bamboo charcoal forms a graphite structure at 300-350℃, the mechanical stability is improved, and the pore structure is optimized, and the micropores can be partially collapsed or merged into mesopores; part of the sulfonic acid groups (-SO3H) can be decomposed or converted (-SO3H groups are unstable at high temperatures and are prone to desulfurization reaction), and the released sulfur-containing substances can react with cerium oxide to generate cerium sulfate or be partially doped into the carbon skeleton; bonding of cerium oxide and sulfur species: the sulfonic acid groups can react with cerium oxide to form surface sulfur-oxygen groups (Ce-O-S), thereby improving the acidity and sintering resistance.

[0054] The method provided by the present application has simple process, renewable substrate material, easy acquisition, large yield and low cost.

[0055] The present application provides a sulfonated bamboo charcoal-based cerium-doped catalyst prepared by the preparation method described in the above technical scheme. In the present application, the sulfonated bamboo charcoal-based cerium-doped catalyst takes bamboo charcoal as a carrier, and S, O and Ce elements are uniformly distributed on the surface and in the pore structure thereof. In the embodiments of the present application, the sulfonated bamboo charcoal-based cerium-doped catalyst is denoted as Ce@SO3H-BC. The sulfonated bamboo charcoal-based cerium-doped catalyst provided by the present application is a solid acid catalyst capable of effectively promoting the desorption of a primary-tertiary diamine CO2 split absorbent rich solution; the primary-tertiary diamine is a diamine compound having both a primary amine and a tertiary amine group in the molecule.

[0056] The present application provides the application of the sulfonated bamboo charcoal-based cerium-doped catalyst described in the above technical scheme in the desorption of an organic amine CO2 split absorbent rich solution, and the organic amine includes a primary-tertiary diamine.

[0057] The present invention has no particular requirements for the primary or tertiary diamine; any primary or tertiary diamine for carbon dioxide absorption known to those skilled in the art, such as DMAPA (cas: 109-55-7), can be used. The sulfonated bamboo charcoal-based cerium-doped catalyst provided by the present invention has excellent catalytic activity, a high specific surface area, a uniform pore structure, and a long service life. It is particularly suitable for desorbing CO2 from a rich solution of a primary or tertiary diamine carbon dioxide phase-separation absorbent, significantly increasing the rich solution desorption rate and reducing the desorption temperature, thereby saving desorption energy consumption.

[0058] Organic amine CO2 absorbers are classified into three categories: primary amines, secondary amines, and tertiary amines, depending on the number of hydrogen atoms in the amino group structure. For primary and secondary amines, the absorption mechanism is a zwitterion reaction, specifically: the organic amine molecule first reacts with CO2 to form a zwitterion (as shown in Formula (1), where R1R2NH represents the organic amine). The zwitterion then undergoes a deprotonation reaction with the base in the solution to form a carbamate ion and a protonated base (as shown in Formula (2), where B represents the base). Unlike primary and secondary amines, tertiary amines do not react directly with CO2, but instead accelerate the CO2 hydration reaction. The mechanism is a base-catalyzed hydration reaction mechanism, as shown in Formula (3) (where R1R2R3N represents the tertiary amine).

[0059] R1R2NH+CO2=R1R2NH + COO - Formula (1)

[0060] R1R2NH + COO - +B=R1R2NCOO - +BH + Formula (2)

[0061]

[0062] The desorption mechanism of the rich liquid is the reverse process of the above absorption mechanism. Catalytic desorption accelerates the desorption reaction by transferring protons between the reactants and the catalyst, which is divided into internal and external diffusion of the reactants and proton transfer processes. Internal and external diffusion are the processes by which reactants such as carbamate ions are transferred to the surface and pores of the catalyst. The specific surface area and pore structure of the catalyst determine whether the reactants can contact efficiently. The proton transfer process directly affects the kinetics of the catalytic desorption reaction, specifically: On the one hand, the acidic sites provide protons to bicarbonate ions, accelerating the decomposition of bicarbonate ions to form CO2; on the other hand, The acidic sites can bind to carbamate ions to form carbamic acid. Furthermore, Lewis acid sites can adsorb to the oxygen end of the C=O bond of carbamic acid, promoting its decomposition.

[0063] The present application takes bamboo charcoal with high specific surface area, rich pore structure, catalytic function, good thermal stability and regeneration as a substrate, respectively introduces The catalyst can accelerate the desorption process of the CO2 phase separation absorbent rich solution, effectively reduce the desorption temperature of the rich solution, thereby reducing the overall desorption energy consumption, and is particularly suitable for the desorption of the primary and tertiary diamine CO2 phase separation absorbent rich solution.

[0064] The present application provides a method for desorbing the rich solution of an organic amine CO2 phase separation absorbent, comprising the following steps:

[0065] The organic amine CO2 phase separation absorbent rich solution is mixed with the catalyst for desorption to obtain CO2; the organic amine includes primary and tertiary diamine, and the catalyst is the Ce@SO3H-BC catalyst as described in the above technical solution; the desorption temperature is 70-120 DEG C.

[0066] In the present application, the mass of the catalyst is preferably 0.5-2% of the mass of the organic amine CO2 phase separation absorbent rich solution, and can be 1% or 1.5%. In the present application, the desorption temperature is 70-120 DEG C, and can be 70, 80, 90 or 100 DEG C; the Ce@SO3H-BC catalyst has good thermal stability in the temperature range of 70-120 DEG C.

[0067] In the present application, the catalyst can be regenerated after use, and the regeneration method is preferably: the catalyst involved in the desorption is filtered and separated, and then is sequentially rinsed and dried.

[0068] In order to further illustrate the present application, the Ce@SO3H-BC catalyst, the preparation method and application thereof provided by the present application are described in detail below with examples, but they should not be understood as limiting the protection scope of the present application.

[0069] Example 1

[0070] The preparation method of the Ce@SO3H-BC catalyst is as follows:

[0071] (1) Phosphoric acid impregnation and anaerobic carbonization treatment of bamboo powder

[0072] The bamboo powder (200 mesh) is added into the phosphoric acid aqueous solution, and impregnated by stirring for 6h. The mass fraction of the phosphoric acid aqueous solution is 50%, and the ratio of the bamboo powder to the phosphoric acid aqueous solution is 1:10 (g:mL). After the impregnation, the excess phosphoric acid aqueous solution in the bamboo powder is removed by vacuum filtration, and the bamboo powder is dried to remove the excess water, to obtain the pretreated bamboo powder. The drying temperature is 80 DEG C, and the time is 12h;

[0073] The pretreated bamboo powder was placed in a tube furnace and carbonized at high temperature under nitrogen protection. The nitrogen flow rate was 200 mL / min. Before heating, the tube furnace was first continuously supplied with nitrogen at 25°C for 30 min to remove residual air in the furnace. The carbonization temperature was initially 25°C, the heating rate was 10°C / min, and the temperature was raised to 350°C. Then, the carbonization was continuously carried out at this temperature for 3 h. After the tube furnace was cooled to room temperature, the nitrogen was turned off, the bamboo charcoal was taken out and repeatedly washed with deionized water until the filtrate was neutral. After washing, the bamboo charcoal powder was placed in an oven at 105°C for drying.

[0074] (2) Preparation of cerium oxide

[0075] An appropriate amount of Ce(NO3)3·6H2O was calcined in a muffle furnace to obtain a light yellow CeO2 powder. The initial calcination temperature was 25°C, the heating rate was 10°C / min, the calcination temperature was 350°C, and the calcination time was 3 h. After calcination, the CeO2 powder was dried in an oven at 105°C for use.

[0076] (3) Sulfonation treatment of the mixture of bamboo charcoal and cerium oxide

[0077] 9 g of bamboo charcoal was mixed with 1 g of cerium oxide, and then 50 mL of 98wt% concentrated sulfuric acid was added. The mixture was immersed at 95°C under strong stirring (stirring rate: 350 rpm) for 6 h. After the stirring and immersion, the product was washed with 200 mL of deionized water, and then filtered and dried to obtain the sulfonated product, which was denoted as powder A. The drying temperature was 105°C, and the drying time was 12 h.

[0078] (4) Obtaining the final catalyst by oxygen-free calcination of powder A

[0079] The powder A was placed in a tube furnace and calcined at high temperature under nitrogen protection to obtain a sulfonated bamboo charcoal-based cerium-doped catalyst, which was denoted as 9:1Ce@SO3H-BC. Before calcination, nitrogen was supplied at 25°C for 30 min to remove residual air in the tube furnace. During calcination, the initial temperature was 25°C, the heating rate was 10°C / min, the calcination temperature was 350°C, and the treatment time was 6 h.

[0080] Example 2

[0081] The mass of cerium oxide in Example 1 was changed to 0.5 g, and the rest was the same as in Example 1 to obtain a sulfonated bamboo charcoal-based cerium-doped catalyst, which was denoted as 9:0.5Ce@SO3H-BC.

[0082] Comparative Example 1

[0083] UIO-66 (commercially available) was used as the catalyst.

[0084] Comparative Example 2

[0085] HZSM-5 molecular sieve is used as a catalyst. The HZSM-5 molecular sieve is made of ZSM-5 molecular sieve. The ZSM-5 molecular sieve is calcined in a muffle furnace at 550° C. for 5.5 hours to obtain HZSM-5.

[0086] Comparative Example 3

[0087] The sulfonated bamboo charcoal catalyst was obtained in the same manner as in Example 1, except that cerium oxide was not added during sulfonation, and was designated as SO3H-BC.

[0088] The structures and properties of the catalysts prepared in the examples and comparative examples were characterized as follows:

[0089] (1) BET aperture test

[0090] Figure 1 Table 1 shows the BET test results of bamboo powder, bamboo carbon, cerium oxide and 9:1Ce@SO3H-BC ( Figure 1 The Ce@SO3H-BC in the carbonization is the 9:1 Ce@SO3H-BC prepared in Example 1. The results show that the carbonization of bamboo powder has a significant pore expansion effect, and the specific surface area is increased from the original 1.49m 2 / g extended to 704.2m 2 / g, which is a suitable substrate material. Compared with bamboo charcoal, the specific surface area and average pore size of Ce@SO3H-BC catalyst are reduced to 542.56m 2 / g and 1.9626nm, proving that the sulfonic acid groups and Ce filled the original pores of bamboo charcoal. At the same time, the pore size of 9:1Ce@SO3H-BC catalyst is larger than the diameter of amine molecules (DMAPA, 0.5-0.8nm) and CO2 molecules (about 0.33nm), which is conducive to the free movement of rich liquid and desorbed CO2. Therefore, using bamboo charcoal as a substrate, by loading sulfonic acid groups and cerium to provide The Ce@SO3H-BC catalyst formed by the acid and Lewis acid active sites can effectively improve the contact area and catalytic efficiency of the rich solution.

[0091] Table 1 Pore parameters of bamboo powder, bamboo charcoal, cerium oxide and 9:1Ce@SO3H-BC

[0092] Pore ​​parameters Bamboo powder bamboo charcoal Cerium oxide <![CDATA[Ce@SO3H-BC]]> <![CDATA[BET比表面积(m 2 / g)]]> 1.49 704.20 76.07 542.56 <![CDATA[孔体积(cm 3 / g)]]> 0.0047 0.3641 0.2525 0.2662 Average pore size (nm) 12.5664 2.0679 13.2765 1.9626

[0093] (2) FT-IR characterization

[0094] Figure 2 FT-IR (Fourier transform infrared spectroscopy) characterization results of bamboo powder, bamboo charcoal, cerium oxide and 9:1Ce@SO3H-BC ( Figure 2The Ce@SO3H-BC in the sample is the 9:1Ce@SO3H-BC prepared in Example 1. As can be seen, bamboo powder exhibits a rich organic signature, while bamboo charcoal obtained from bamboo powder through phosphoric acid impregnation and oxygen-free carbonization exhibits significantly reduced organic impurities. Furthermore, bamboo charcoal contains functional groups such as CO and C=O, which inherently possess certain catalytic properties, making it more suitable as a catalyst substrate. Compared to bamboo charcoal and cerium oxide in FT-IR, 9:1Ce@SO3H-BC exhibits characteristic peaks such as S=O, SO, and Ce-O, indicating successful loading of sulfonic acid groups and cerium.

[0095] (3) SEM and EDS surface scanning results

[0096] Figure 3 The SEM and EDS scan results of 9:1Ce@SO3H-BC catalyst are shown. Figure 3 (a) is the SEM image, (b) is the EDS scan, (c) is the EDS scan-C, (d) is the EDS scan-S, (e) is the EDS scan-O, and (f) is the EDS scan-Ce. Figure 3 It can be seen from the SEM image that the Ce@SO3H-BC catalyst presents an irregular granular structure with a particle size of 20 to 60 μm. Figure 3 The EDS image shows that a large amount of carbon elements are evenly distributed, confirming that the bamboo charcoal formed by pore expansion and carbonization of bamboo powder is the carrier, and the S, O, and Ce elements are evenly distributed on its surface and in the pore structure.

[0097] (III) Thermal stability analysis: TGA-DTG characterization

[0098] The TGA thermogravimetric analysis of bamboo charcoal, CeO2 and Ce@SO3H-BC showed the following results: Figure 4 As shown ( Figure 4 The Ce@SO3H-BC in the figure is the 9:1Ce@SO3H-BC prepared in Example 1). When the temperature is lower than 150°C, the masses of bamboo charcoal, CeO2 and 9:1Ce@SO3H-BC decrease by 0.5027wt%, 0.5027wt% and 0.6203wt%, respectively. This weight loss is presumably due to the removal of adsorbed and bound water. When the temperature is between 400 and 600°C, the DTA curve of bamboo charcoal is relatively smooth, while Ce@SO3H-BC has a large DTG weight loss peak, which may be caused by the decomposition of the catalyst at high temperature or the collapse and decomposition of the pore structure of the bamboo charcoal substrate. Overall, within the amine-rich solution desorption temperature (70 to 120°C), Ce@SO3H-BC loses weight slowly, demonstrating its good thermal stability.

[0099] (IV) Desorption performance of rich liquid

[0100] Desorption step: CO2 absorption and desorption device such as Figure 5As shown, the simulated flue gas consisting of 10% CO2 and 90% N2 was passed into the constant temperature absorption reactor containing the split-phase absorbent until the split-phase absorbent was saturated. The simulated flue gas flow was 1 L / min, and the absorption temperature was 40°C. After the absorption was completed, 10 g of the rich solution and 0.1 g of the catalyst were added into the constant temperature desorption reactor, the mixed gas of CO2, amine and water was desorbed from the rich solution under the action of heat, and was carried by the carrier gas N2 to pass through the condenser and the dryer in sequence and then was passed into the CO2 analyzer to obtain and record the real-time mass fraction of CO2. The split-phase absorbent used was a sulfolane aqueous solution of DMAPA. The solute of the amine solution was DMAPA, which was a primary and secondary diamine, the concentration was 2 M, and the solvent was sulfolane and water, the volume ratio was 6:4. The CO2 desorption amount was obtained by calculation according to formula (4) to (5). The carrier gas N2 flow during desorption was 500 mL / min, and the desorption temperature was 90°C. The blank group (Blank) was the same as each example and the control example except that no catalyst was added.

[0101] α = Q C / (Q C + Q N ) Formula (4)

[0102]

[0103] In formula (4) to (5), α is the real-time mass fraction of CO2; Q C is the mass flow of desorbed CO2, mL / min; Q N is the mass flow of the carrier gas N2, mL / min; V C is the cumulative desorption amount of CO2 from 0 to t, mL.

[0104] Figure 6 and Figure 7 are the instantaneous desorption rate of CO2 and the total desorption amount of CO2 under the action of different catalysts, respectively. Compared with the blank group, the commercial catalysts in the control examples 1 and 2 not only have no promoting effect on the desorption process of the split-phase absorbent rich solution, but also make the total desorption amount of CO2 decrease by 31.06% and 12.51%, respectively. Compared with the catalyst without cerium in the control example 3, the cerium-doped catalyst in the example 1 has obvious advantages in the instantaneous desorption rate of CO2 and the total desorption amount of CO2, which proves that the Lewis acid sites of the catalyst are successfully increased by introducing cerium elements, and the catalytic activity is greatly increased. In summary, the catalyst in the example 1 of the present application makes the maximum desorption rate of CO2 increase from 0.1063 mL / s of the blank group to 0.2216 mL / s, and the total desorption amount (20 min) is 48.91% higher than that of the blank group. The desorption rate of the catalyst in the example 2 is slightly lower than that in the example 1, and the total desorption amount is 47.39% higher than that of the blank group, which proves that the catalysts of the present application have excellent ability to promote the desorption of the split-phase absorbent rich solution.

[0105] Figure 8 is the cumulative desorption amount of CO2 under different catalysts. For the phase separation absorbent rich liquid desorption reaction under the action of Blank, SO3H-BC, Ce@SO3H-BC, UIO-66 and HZSM-5, the order of CO2 desorption amount is UIO-66. <HZSM-5<Blank<SO3H-BC<9:0.5Ce@SO3H-BC<9:1Ce@SO3H-BC。可看出,Ce@SO3H-BC对分相吸收剂富液的催化解吸效果最显著,CO2解吸量高达155.43mL。此外,本实验解吸温度为90℃,远低于常规富液解吸的温度(120~140℃),因此本发明Ce@SO3H-BC催化剂能显著降低分相吸收剂解吸反应所需能耗。

[0106] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation thereto. It should be noted that those skilled in the art may make various improvements and modifications without departing from the principles of the present invention, and such improvements and modifications shall also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a sulfonated bamboo charcoal-based cerium-doped catalyst, characterized in that: The following steps are involved: The bamboo charcoal, cerium oxide and concentrated sulfuric acid are mixed to carry out a sulfonation reaction to obtain a sulfonated product; The sulfonated product is subjected to oxygen-free calcination to obtain the sulfonated bamboo charcoal-based cerium-doped catalyst.

2. The preparation method according to claim 1, characterized in that The mass ratio of the bamboo charcoal to cerium oxide is 9:0.5-1.

3. The preparation method according to claim 1, characterized in that The mass fraction of the concentrated sulfuric acid is 98%, and the usage ratio of the bamboo charcoal to the concentrated sulfuric acid is 0.1-0.3 g:1 mL.

4. The preparation method according to any one of claims 1 to 3, characterized in that The temperature of the sulfonation reaction is 90-100° C., and the time is 4-8 hours.

5. The preparation method according to claim 1, characterized in that The temperature of the oxygen-free calcination is 300-350° C., and the time is 4-8 hours.

6. The preparation method according to claim 1, characterized in that The preparation method of the bamboo charcoal comprises the following steps: mixing bamboo powder with a phosphoric acid aqueous solution for pretreatment to obtain pretreated bamboo powder; Carbonizing the pretreated bamboo powder in an oxygen-free state to obtain the bamboo charcoal; The mass fraction of the phosphoric acid aqueous solution is 30-50%, the usage ratio of the bamboo powder to the phosphoric acid aqueous solution is 1g:10mL; the pretreatment time is 4-8h; the temperature of the anaerobic carbonization is 300-350°C, and the time is 3-5h.

7. The preparation method according to claim 1, characterized in that The preparation method of cerium oxide comprises the following steps: Ce(NO3)3 is calcined to obtain cerium oxide; the calcination temperature is 350°C, the time is 3 hours, and the calcination is carried out in an air atmosphere.

8. The sulfonated bamboo charcoal-based cerium-doped catalyst prepared by the preparation method according to any one of claims 1 to 7.

9. Use of the sulfonated bamboo charcoal-based cerium-doped catalyst according to claim 8 in the desorption of rich solution of an organic amine carbon dioxide phase-separation absorbent, wherein the organic amine comprises a primary or tertiary diamine.

10. A method for desorbing rich liquid using an organic amine carbon dioxide phase separation absorbent, characterized in that: The following steps are involved: The organic amine carbon dioxide phase separation absorbent rich liquid is mixed with a catalyst for desorption to obtain carbon dioxide; the organic amine includes primary and tertiary diamines, and the catalyst is the sulfonated bamboo charcoal-based cerium-doped catalyst according to claim 8; the desorption temperature is 70-120°C.

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