A transition metal sulfide material for carbon dioxide catalytic regeneration and adsorption, and a preparation method and use thereof

Abstract

The application provides a transition metal sulfide material for carbon dioxide catalytic regeneration and adsorption, and a preparation method and use thereof. The preparation method of the transition metal sulfide material comprises the following steps: S1: dissolving a transition metal precursor and a sulfur precursor in water or an alcohol-water mixed solvent, uniformly mixing, and then adding into a reaction kettle to perform hydrothermal treatment; S2: after the material after the hydrothermal treatment is washed with deionized water and anhydrous ethanol and dried, annealing treatment is performed to obtain the transition metal sulfide material; wherein the transition metal precursor is a salt of a transition metal element, and the molar ratio of the transition metal element to sulfur in the sulfur precursor is 1:1-1:16. The transition metal sulfide catalytic regeneration material obtained by the preparation method has high activity and high stability, can improve carbon capture CO2 desorption kinetics, and further reduce the energy consumption and carbon capture operation cost of the CO2 desorption process, and realizes energy saving and emission reduction.

Description

Technical Field

[0001] This invention relates to a transition metal sulfide material for catalytic regeneration and adsorption of carbon dioxide, its preparation method and uses, belonging to the field of greenhouse gas capture and energy conservation. Background Technology

[0002] Coal-fired flue gas is a major source of carbon emissions. To achieve the goal of "carbon peaking and carbon neutrality," the development of pollution reduction and carbon reduction technologies and green electricity is particularly crucial. Currently, amine absorption methods such as MEA (Medium-Alkali Absorption) are widely used for carbon capture after coal-fired flue gas combustion due to their rapid absorption, mature technology, and compatibility with existing technological systems. However, the strong bond between the nitrogen atoms in amines and CO2, and the difficulty in precisely controlling the proton migration process under alkaline conditions, lead to higher CO2 desorption temperatures (typically between 110 and 130°C). Therefore, energy costs significantly limit the technological advancement and further promotion of amine absorption methods.

[0003] Given the high energy consumption of the amine absorption method, developing highly active solid acid materials to improve mass and heat transfer and kinetics in the CO2 desorption process is an effective way to promote the development of low-energy carbon capture technology. For solid acid-catalyzed CO2 desorption processes, patent CN110681413A proposes a method for preparing a FeZr@composite molecular sieve catalyst for desorption of CO2-rich amine solutions. Patent CN110681410A proposes a method for preparing an SBA-15 molecular sieve-based supported catalyst for desorption of CO2-rich amine solutions. These research results indicate that adding solid acid can act as an acidic site, improving CO2 desorption efficiency.

[0004] However, the composite catalysts studied in the above methods are produced by loading metal oxides onto a molecular sieve support and enhancing the acidity of the solid by sulfuric acid acidification. Since the amine-based carbon capture system operates under extremely harsh conditions such as high temperature and strong oxidizing properties, and organic amines and metals readily form stable metal-N coordination structures, problems such as catalyst oxidation, poisoning, and leaching occur, severely affecting the catalyst's cycle stability. Summary of the Invention

[0005] The problem the invention aims to solve

[0006] In view of the technical problems existing in the prior art, in order to further improve the quality of amine solvent regeneration and effectively reduce the temperature and energy consumption of amine solvent regeneration, it is necessary to provide a new type of high-efficiency catalyst for the carbon capture absorbent regeneration process.

[0007] Solution for solving the problem

[0008] This invention first provides a method for preparing transition metal sulfide materials for catalytic regeneration and adsorption of carbon dioxide, comprising the following steps:

[0009] S1: Dissolve the transition metal precursor and the sulfur precursor in water or an alcohol-water mixture, mix them thoroughly, and then add them to the reaction vessel for hydrothermal treatment.

[0010] S2: The hydrothermally treated material is cleaned and dried with deionized water and anhydrous ethanol, and then annealed to obtain a transition metal sulfide material.

[0011] Wherein, the transition metal precursor is a salt of a transition metal element, and the molar ratio of the transition metal element to the sulfur element in the sulfur precursor is 1:1 to 1:16.

[0012] The transition metal element includes at least one of molybdenum and tungsten.

[0013] According to the preparation method of the present invention, the sulfur precursor includes one or more of thiourea, thioacetamide, and sodium sulfide; and / or,

[0014] The salts of the transition metal elements include at least one of the chlorides, nitrates, and oxoacids of the transition metal elements.

[0015] According to the preparation method of the present invention, in step S1, the hydrothermal treatment temperature is 150~180℃, and the hydrothermal treatment time is 24~36h; and / or,

[0016] In step S1, the volume ratio of alcohol to water in the alcohol-water mixed solvent is 1:1 to 1:10, and the alcohol includes at least one of ethanol, ethylene glycol, and isopropanol; and / or,

[0017] In step S2, the annealing temperature is 100~600℃, and the annealing time is 1~3 hours; and / or,

[0018] In step S2, the annealing process is carried out under a nitrogen or argon atmosphere.

[0019] This invention also provides a transition metal sulfide material for catalytic regeneration and adsorption of carbon dioxide, which is prepared by the preparation method described in this invention.

[0020] The transition metal sulfide material is a nanosphere-shaped transition metal sulfide, formed by stacking two-dimensional layered transition metal sulfides; the interlayer spacing of the two-dimensional layered structure is 0.62 nm to 0.95 nm; the active center of the transition metal sulfide includes surface acidic sites, which include Li acid sites and Beta acid sites, and the molar ratio of Li acid sites to Beta acid sites is 1:0.5 to 1:5.

[0021] According to the transition metal sulfide material of the present invention, the transition metal sulfide material contains sulfur vacancy defects, wherein the unsaturated transition metal atom at the sulfur vacancy defect is a bifunctional site of L acid and Brønsted acid.

[0022] According to the transition metal sulfide material of the present invention, the particle size of the nanosphere transition metal sulfide is 300~600 nm.

[0023] According to the transition metal sulfide material of the present invention, the transition metal sulfide material has a microporous and / or mesoporous structure; the specific surface area of ​​the transition metal sulfide material is 10 m². 2 The transition metal sulfide material has a pore volume of 0.001 cm³ / g or more. 3 The average pore size of the transition metal sulfide material is 30~40nm, with a density of ≥g.

[0024] The present invention also provides a use of the transition metal sulfide material according to claim 1, wherein the transition metal sulfide material is used in the catalytic regeneration of carbon capture amine absorbent and in the carbon dioxide capture and regeneration.

[0025] According to the application described in this invention, the method for catalytic regeneration of the carbon-capturing amine absorbent includes: adding the transition metal sulfide material to a carbon dioxide-loaded amine-rich absorbent, wherein the amine absorbent includes one or more of monoethanolamine, diethanolamine, methyldiethanolamine, and 2-amino-2-methyl-1-propanol, and under the catalytic action of the transition metal sulfide material, the regeneration temperature of the amine-rich absorbent is 80~110°C, and the carbon dioxide desorption rate is increased by more than 20% in the same time period compared to the condition without a catalyst.

[0026] According to the application described in this invention, the use of the transition metal sulfide material in carbon dioxide capture and regeneration includes: filling the transition metal sulfide material as a heterogeneous catalyst in a regeneration tower, allowing the amine-rich absorbent to flow through the packing layer containing the material, and desorbing by heating, wherein the catalytic activity of the transition metal sulfide material is maintained at over 95% after 10 days of cyclic regeneration.

[0027] The effects of the invention

[0028] Compared with existing technologies, the catalytic regeneration material of the present invention has at least the following technical advantages:

[0029] (1) The transition metal sulfide catalytic regeneration material obtained by the preparation method provided by the present invention has high activity and high stability, which can improve the carbon capture CO2 desorption kinetics, thereby reducing the energy consumption of the CO2 desorption process and the carbon capture operation cost, and achieving the purpose of energy saving and emission reduction.

[0030] (2) The active sites in the transition metal sulfide material provided by the present invention include surface acidic sites, wherein the surface acidic sites include vacant sulfur sites (within the two-dimensional material basal plane) and edge sites. The surface acidic sites achieve dynamic proton supply through the "edge transition metal-vacant sulfur" dual-site mechanism, which has higher reaction activity and stability compared with supported catalysts.

[0031] (3) The transition metal sulfide material provided by the present invention has good dispersibility and can be used as a nanofluid or as a complete packing material in existing CO2 capture devices. It can effectively improve flue gas treatment efficiency and alleviate the secondary aerosol pollution and equipment corrosion caused by absorbent volatilization at high temperatures.

[0032] (4) The transition metal sulfide material provided by the present invention can be used as a heterogeneous catalyst to accelerate the absorption efficiency of CO2 by amine solvent. Attached Figure Description

[0033] Figure 1 A schematic diagram showing the structure of the transition metal sulfide material of the present invention;

[0034] Figure 2 The images show scanning electron microscope images of the catalysts prepared in Examples 1-3.

[0035] Figure 3 The nitrogen adsorption-desorption isotherm of the catalyst prepared in Example 1 is shown.

[0036] Figure 4 The X-ray diffraction spectra of the catalysts obtained in Examples 1-5 are shown.

[0037] Figure 5 The ammonia-temperature-increase adsorption-desorption curves of the catalysts prepared in Examples 1-5 are shown.

[0038] Figure 6 The figure shows the full width at half maximum (FWHM) of the (002) diffraction peak of the catalysts prepared in Examples 1-3 and the fitting graph of the sulfur content measured by inductively coupled plasma atomic emission spectrometry.

[0039] Figure 7 The electron paramagnetic resonance spectra of vacant sulfur in the catalysts prepared in Examples 1-3 are shown.

[0040] Figure 8 The graphs show the CO2 desorption activity of the catalysts prepared in Examples 1-6 under both non-catalytic (blank) and non-catalytic (blank) conditions.

[0041] Figure 9 The graphs show the CO2 desorption activity test results of the catalysts obtained in Examples 1 and Comparative Examples 1-3 under non-catalytic (blank) conditions;

[0042] Figure 10 (a) in the figure represents the test graph of the catalyst obtained in Example 1 for 1 to 8 cycles; Figure 10 (b) in the figure represents a comparison of the activity curves of the catalyst obtained in Example 1 after 10 days of cyclic regeneration. Detailed Implementation

[0043] Various exemplary embodiments, features, and aspects of the present invention will be described in detail below. The term "exemplary" as used herein means "serving as an example, embodiment, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as superior to or better than other embodiments.

[0044] Furthermore, to better illustrate the present invention, numerous specific details are set forth in the following detailed embodiments. Those skilled in the art should understand that the present invention can be practiced without certain specific details. In other instances, methods, means, apparatus, and steps well known to those skilled in the art have not been described in detail in order to highlight the spirit of the present invention.

[0045] Unless otherwise stated, all units used in this specification are international standard units, and all numerical values ​​and ranges appearing in this invention should be understood to include systematic errors that are unavoidable in industrial production.

[0046] In this specification, the word "may" has two meanings: to perform a certain process and not to perform a certain process.

[0047] In this specification, references to "some specific / preferred embodiments," "other specific / preferred embodiments," "implementation," etc., refer to specific elements (e.g., features, structures, properties, and / or characteristics) related to that embodiment, which are included in at least one of the embodiments described herein and may or may not be present in other embodiments. Furthermore, it should be understood that these elements may be combined in any suitable manner in various embodiments.

[0048] In this specification, the range of values ​​referred to as "value A to value B" refers to the range including the endpoint values ​​A and B.

[0049] [First aspect]

[0050] The first aspect of the present invention provides a method for preparing a transition metal sulfide material for catalytic regeneration and adsorption of carbon dioxide, comprising the following steps:

[0051] S1: Dissolve the transition metal precursor and the sulfur precursor in water or an alcohol-water mixture, mix them thoroughly, and then add them to the reaction vessel for hydrothermal treatment.

[0052] S2: The hydrothermally treated material is cleaned and dried with deionized water and anhydrous ethanol, and then annealed to obtain a transition metal sulfide material.

[0053] The transition metal precursor is a salt of a transition metal element, and the molar ratio of the transition metal element to the sulfur element in the sulfur precursor is 1:1 to 1:16.

[0054] Specifically, this invention involves first synthesizing a transition metal sulfide precursor via a hydrothermal method, followed by programmed temperature annealing under inert gas protection. High temperatures facilitate crystal growth, and during this growth process, an excess of sulfur precursor increases vacant sulfur sites, thereby forming "edge transition metal-vacant sulfur" dual-site acidic sites on the surface of the transition metal sulfide material. The acidic sites on the surface of the transition metal sulfide material provided by this invention achieve dynamic proton supply through the "edge transition metal-vacant S" dual-site mechanism, resulting in two-dimensional transition metal sulfide materials with excellent activity and stability.

[0055] The following provides a detailed explanation of each step.

[0056] (Step S1)

[0057] In step S1 of the present invention, the transition metal precursor and the sulfur precursor are dissolved in water or an alcohol-water mixed solvent, mixed evenly, and then added to a reaction vessel for hydrothermal treatment.

[0058] The transition metal precursor is a salt of a transition metal element, including at least one of molybdenum and tungsten. When the transition metal is molybdenum or tungsten, the transition metal sulfide exhibits a two-dimensional structure, and the two-dimensional layers are stacked to form a nanoflower structure. The layered configuration of sulfur-transition metal-sulfur can expose more active sites, and the exposed sites at the layer edges participate in the reaction.

[0059] The type of salt is not particularly limited and may include at least one of the following: chlorides of transition metal elements, nitrates of transition metal elements, and oxoacid salts of transition metal elements.

[0060] In some specific embodiments, the sulfur precursor may include one or more of thiourea, thioacetamide, and sodium sulfide, with thiourea being the preferred choice.

[0061] The molar ratio of the transition metal element in the salt to the sulfur element in the sulfur precursor is 1:1 to 1:16; for example, it can be 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, 1:12, 1:14, etc. When the amount of the transition metal salt added is too low, the sulfur vacancies formed by the excess sulfur precursor etching material will not continue to increase, the structure of the resulting transition metal sulfide will not continue to change, and the number of active sites will not continue to increase. When the amount of the transition metal salt added is too high, the material sulfidation is incomplete, the excess metal is in an unstable free state, and may be dissolved by the solvent, causing pollution to the catalytic reaction system. When the molar ratio of the transition metal element to the sulfur element in the sulfur precursor is 1:1 to 1:16, there are abundant in-plane sulfur vacancies and edge sites, the nanoflower structure is stable, and the stability of the transition metal sulfide material can be effectively improved.

[0062] In some specific implementations, the temperature of the hydrothermal treatment can be 150~180℃, for example, 150℃, 160℃, 170℃, 180℃, etc.; the time of the hydrothermal treatment can be 24~36h, for example, 26h, 28h, 30h, 32h, 34h, etc.

[0063] (Step S2)

[0064] In step S2 of the present invention, the hydrothermally treated material is washed with deionized water and dried, and then annealed to obtain a transition metal sulfide material.

[0065] In some specific implementations, the annealing temperature can be 100~600℃, for example, 350℃, 400℃, 450℃, 500℃, 550℃, etc., preferably 400℃, and more preferably, the heating rate of the annealing is controlled at 2~5℃ / min; the annealing time is 2~4h, for example, 2.5h, 3h, 3.5h, etc. When the annealing is performed under the above conditions, the transition metal sulfide material can form a more stable crystal form while improving the activity of the material.

[0066] In some specific implementations, the annealing process is carried out under a nitrogen or argon atmosphere, preferably nitrogen.

[0067] [Second aspect]

[0068] A second aspect of this invention provides a transition metal sulfide material for catalytic regeneration and adsorption of carbon dioxide, prepared according to the preparation method described in the first aspect. The transition metal sulfide material provided by this invention is a nanosphere-shaped transition metal sulfide, formed by stacking two-dimensional layered transition metal sulfides. The interlayer spacing of the two-dimensional layered structure is 0.62 nm to 0.95 nm, for example, 0.65 nm, 0.68 nm, 0.7 nm, 0.75 nm, 0.8 nm, 0.85 nm, 0.9 nm, etc. This interlayer spacing is the basic interlayer spacing of the transition metal sulfide, caused by interlayer van der Waals forces. The sulfur-transition metal-sulfur layered configuration can expose more active sites, with the exposed sites at the layer edges participating in the reaction. Furthermore, annealing treatment transforms the crystal structure of molybdenum sulfide or tungsten sulfide from the 1T phase to the 2H phase, making the crystal structure more stable and improving its activity.

[0069] The active center of the transition metal sulfide of the present invention includes surface acidic sites, which include Li acid sites and Brønsted acid sites, and the molar ratio of Li acid sites to Brønsted acid sites is 1:0.5 to 1:5, for example, 1:0.8, 1:1, 1:2, 1:3, 1:4, etc.

[0070] The transition metal sulfide material of this invention contains sulfur vacancy defects, wherein the vacant sulfur is generally in-plane. The transition metal atoms surrounding the vacant sulfur are unsaturated in coordination, resulting in a lower valence state and increased attraction for electrons. This makes it easier to adsorb -OH (hydroxyl groups) from water, forming transition metal -OH coordination sites. The transition metal atoms surrounding the vacant sulfur act as Lewis acid sites. The edge sulfur can directly react with H in water. ＋ They pair up to form SH bonds, which act as sites for Brønsted acid (B-acid).

[0071] In some specific implementations, the unsaturated transition metal atom at the sulfur vacancy defect can be a bifunctional site for both Lewis acid and Beta acid.

[0072] The transition metal elements of this invention are the same as those described in the first aspect, and will not be repeated here.

[0073] The transition metal sulfide material of the present invention can be made from MS x -y represents M, where M represents a transition metal, x represents the amount of sulfur in different metal sulfides, and y represents the molar ratio of sulfur to metal in the precursor. Figure 1 The structure of the transition metal sulfide material of the present invention is illustrated using MoS2 as an example. Figure 1 As shown, the two-dimensional layered stacking forms a nanoflower structure, exposing more of the layered edges.

[0074] In some specific implementations, the molar ratio of the transition metal element to the sulfur element in the transition metal sulfide material is 1:1.8 to 1:2.1, for example, it can be 1:1.85, 1:1.9, 1:1.95, 1:2, 1:2.05, etc.

[0075] In some specific implementations, the particle size of the nano-transition metal sulfide is 300~600nm, for example, it can be 350nm, 400nm, 420nm, 450nm, 480nm, 500nm, 520nm, 550nm, or 580nm.

[0076] In some specific embodiments, the transition metal sulfide material has a microporous and / or mesoporous structure, and the specific surface area of ​​the transition metal sulfide material is 10 m². 2 / g or more, preferably 11m 2 / g or more, preferably 12m 2 / g or more; the pore volume of the transition metal sulfide material is 0.001 cm³. 3 / g or more, preferably 0.0011cm 3 / g or more, more preferably 0.0012cm 3 / g or more; the average pore size of the transition metal sulfide material is 30~40nm, for example, it can be 31nm, 32nm, 33nm, 34nm, 35nm, 36nm, 37nm, 38nm, 39nm, etc.

[0077] [Third aspect]

[0078] A third aspect of the present invention provides the use of a transition metal sulfide material prepared according to the method for preparing the transition metal sulfide material according to the first aspect or according to the second aspect, the use of which may include use in the catalytic regeneration of a carbon capture amine absorbent and use in carbon dioxide capture and regeneration.

[0079] Specifically, the application of the aforementioned catalytic regeneration of carbon-capturing amine absorbents can include: adding the transition metal sulfide material to a carbon dioxide-loaded amine-rich absorbent. By introducing a catalyst into the regeneration process of the amine absorbent, proton transfer can be accelerated, effectively inducing the breaking of carbon-nitrogen bonds in the reactants. Under the catalytic action of the transition metal sulfide material, the regeneration temperature of the amine-rich absorbent is 80~110℃, and compared to conditions without a catalyst, the carbon dioxide desorption rate is increased by more than 20% within the same time period.

[0080] The absorbent can be an alcohol amine solution absorbent, such as a complex amine absorbent, a low-water absorbent, or a phase change absorbent. Specifically, examples include one or more mixed amine solutions of monoethanolamine (MEA), diethanolamine (DEA), methyldiethanolamine (MDEA), and 2-amino-2-methyl-1-propanol (AMP).

[0081] Transition metal sulfide materials are used as catalysts in this application. The method of using the catalyst in this application is not particularly limited. The catalyst can be used by mixing it with the absorbent solution. Specifically, it may include the following steps: mixing the catalyst particles with the absorbent solution and ultrasonically dispersing them before adding them to the carbon capture system.

[0082] The particle size of the catalyst particles is not particularly limited and can be selected as needed, for example, catalyst particles of 60 to 200 mesh can be selected.

[0083] The amount of the catalyst can be 0.05wt% to 0.2wt% of the total amount of the absorbent solution, preferably 0.1wt%.

[0084] The application of the transition metal sulfide material in carbon dioxide capture and regeneration can include: filling the regeneration tower with the transition metal sulfide material as a heterogeneous catalyst, allowing the amine-rich absorbent to flow through the packing layer containing the material, and desorbing by heating. After 10 days of cyclic regeneration, the catalytic activity of the transition metal sulfide material is maintained at over 95%.

[0085] Example

[0086] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0087] Example 1

[0088] Preparation method of MoS2-4 catalyst for catalytic regeneration:

[0089] S1: Add 1 mmol of ammonium molybdate and 28 mmol of thiourea to a 50 ml polytetrafluoroethylene liner containing 40 ml of water. After placing the liner in a hydrothermal reactor, heat it in an oven at 180°C for 24 hours to obtain the MoS2 precursor.

[0090] S2: After repeatedly washing the precursor material obtained in S1 with deionized water, dry it in a vacuum oven at 60°C for 6 hours. Then, put the dried material into a tube furnace and heat it to 400°C at 5°C / min for 2 hours under nitrogen protection.

[0091] Example 2

[0092] Preparation method of MoS2-1 catalyst for catalytic regeneration:

[0093] The only difference from Example 1 is that the 28 mmol thiourea in Example 1 is replaced with 7 mmol thiourea, while the other steps and dosages are the same as in Example 1.

[0094] Example 3

[0095] Preparation method of MoS2-2 catalyst for catalytic regeneration:

[0096] The only difference from Example 1 is that the 28 mmol thiourea in Example 1 is replaced with 14 mmol thiourea, while the other steps and dosages are the same as in Example 1.

[0097] Example 4

[0098] Preparation method of MoS2-4-thioacetamide catalyst for catalytic regeneration:

[0099] The only difference from Example 1 is that the 28 mmol thiourea in Example 1 is replaced with 28 mmol thioacetamide, while the other steps and dosages are the same as in Example 1.

[0100] Example 5

[0101] The difference from Example 1 is that the annealing temperature in step S2 is replaced with 100°C instead of 400°C, while the other steps and dosages are the same as in Example 1.

[0102] Example 6

[0103] Preparation method of WS2 catalyst, a catalytic regeneration material:

[0104] The difference from Example 1 is that 1 mmol ammonium molybdate in step S1 is replaced with 1 mmol ammonium tungstate, while the other steps and dosages are the same as in Example 1.

[0105] Comparative Example 1

[0106] Preparation method of MoO3 catalyst for catalytic regeneration:

[0107] S1: 10 mmol of ammonium molybdate was placed in a quartz boat and heated in a muffle furnace at 400°C for 24 h to obtain the MoO3 catalyst.

[0108] Comparative Example 2

[0109] Preparation method of Ni-NiO catalyst for catalytic regeneration:

[0110] S1: 10 mmol of nickel nitrate was placed in a quartz boat and heated in a muffle furnace at 400°C for 24 h to obtain the Ni-NiO catalyst.

[0111] Comparative Example 3

[0112] Catalytic regeneration material SO4 2- Preparation method of ZrO2 catalyst:

[0113] S1: Add 10 mmol ZrO2 to 100 ml concentrated sulfuric acid, stir for 1 hour, filter, wash and dry to obtain SO4. 2- / ZrO2 catalyst.

[0114] Performance testing

[0115] 1. Electron microscopy (SEM) test

[0116] The catalysts prepared in Examples 1-3 were tested using scanning electron microscopy. The results are as follows: Figure 2 As shown.

[0117] Depend on Figure 2 It can be seen that the stacked two-dimensional layered structure forms nanoflower-like MoS2, with abundant exposed edges of the sheet-like structure in Example 1. Figure 1 As shown in the synthesis diagram, excessive sulfur precursor leads to the formation of numerous defects, and the abundance of defects is the main reason for the rich edge distribution. The diameter of the nanoflowers is approximately 350-450 nm, indicating that the methods in Examples 1-3 can effectively synthesize stable MoS2 catalysts.

[0118] 2. Specific surface area, pore volume, and pore size testing

[0119] The specific surface area, pore volume, and pore size of the MoS2 catalyst prepared in Example 1 were tested using the BET method. The test results are as follows: Figure 3 As shown in Table 1.

[0120] Depend on Figure 3 It can be seen that the MoS2 catalyst prepared in Example 1 has microporous and mesoporous structures, belonging to a hierarchical porous structure.

[0121] The specific surface area, pore volume, and pore size of the MoS2 catalysts prepared in Examples 1-3 were tested using the BET method, and the test results are shown in Table 1.

[0122] Table 1

[0123]

[0124] As shown in Table 1, the specific surface areas of Examples 1-3 range from 11.9 to 17.0 m². 2 Between the S / g and S / Mo ratios, as the sulfur content in the precursor increases (sulfur content was subsequently determined by solid-state ICP), the specific surface area of ​​the resulting MoS2 catalysts with different S / Mo ratios increases accordingly. This is because excess sulfides etch the basal surface of the already formed MoS2 layer under high temperature and high pressure conditions (hydrothermal process), reducing the monolayer area of ​​the two-dimensional MoS2 sheets. In other words, under unit mass conditions, more two-dimensional MoS2 sheets participate in stacking to form a nanoflower-like microstructure. Therefore, a moderate increase in the sulfur ratio leads to an increase in the specific surface area of ​​MoS2. Simultaneously, the stacking of a large number of two-dimensional MoS2 sheets with small monolayer areas also explains the decrease in average pore size while the pore area increases.

[0125] 3. X-ray diffraction spectroscopy (XRD)

[0126] The MoS2 catalysts obtained in Examples 1-5 were subjected to X-ray diffraction spectroscopy tests, and the results are as follows: Figure 4 As shown.

[0127] from Figure 4 It can be seen that Example 5, with an annealing temperature of 100℃, maintains the 1T configuration. The MoS2 catalysts in Examples 1-4 all conform to the 2H-MoS2 crystal form, meaning that when the annealing temperature reaches a certain temperature (400℃), the sulfur content in the precursor does not affect the crystal form of MoS2; it is predominantly 2H-MoS2, resulting in a more stable crystal form. Combined with activity tests, it is shown that 2H-MoS2 has more active sites and is more prone to adsorbing carbamates and transferring protons.

[0128] 4. Ammonia-Programmed Temperature Adsorption-Desorption Test (NH3-TPD)

[0129] The MoS2 catalysts prepared in Examples 1-5 were subjected to ammonia-temperature-programmed adsorption-desorption tests. The results are as follows: Figure 5 As shown.

[0130] Depend on Figure 5It can be seen that the NH3 desorption curves of MoS2 catalysts with different sulfur contents all show desorption peaks at 150℃, 185℃, 230℃, and 270℃. The desorption peaks around 150℃ and 185℃ represent Lewis acid sites (vacant sulfur sites), while the desorption peaks around 230℃ and 270℃ represent weak Brønsted acids (marginal transition metal molybdenum sites), realizing dynamic proton transfer between the marginal transition metal molybdenum sites and vacant sulfur sites. Integral semi-quantitative analysis of the NH3 molecule desorption peaks reveals that the catalysts prepared in Examples 1, 2, and 3 show desorption peak area ratios between 1:1 and 1:1.5 at 150℃, 185℃, 230℃, and 270℃, verifying that the marginal transition metal molybdenum sites and vacant sulfur sites act as Brønsted acid and Lewis acid, respectively, accelerating the transfer of protons and substrate carbamates, thereby speeding up the reaction process.

[0131] 5. Inductively Coupled Plasma Atomic Emission Spectrometer (ICP-AES)

[0132] The X-ray diffraction spectra of the MoS2 catalysts prepared in Examples 1-3 were fitted with the half-peak width of the (002) plane of the test material and the mass fraction of sulfur in the catalyst obtained by inductively coupled plasma atomic emission spectrometry (ICP). Figure 6 .

[0133] Figure 6 In the diagram, the vertical axis represents the 002 crystal plane (longitudinal section) of the material, and the horizontal axis represents the mass percentage content of sulfur in the material. According to the Scherrer equation, the larger the half-width at half-maximum (FWHM) of the 002 crystal plane peak, the smaller the corresponding grain size (FWHM is inversely proportional to grain size). Figure 6 It can be seen that as the sulfur content increases, the grain size of the material becomes smaller. Excess sulfur precursors generate H2S and SO2 components during the hydrothermal process, which etch the basal surface of molybdenum disulfide, thereby generating sulfur vacancies. Large areas of sulfur vacancies then split the crystal plane to form small-sized grains.

[0134] 6. Electron paramagnetic resonance spectroscopy (EPR) measurement

[0135] The MoS2 catalysts prepared in Examples 1-3 were subjected to electron paramagnetic resonance spectroscopy. The test results are as follows: Figure 7 As shown. From Figure 7 The electron paramagnetic resonance spectrum shows that the sample obtained from the excess sulfur precursor has more sulfur vacancies, consistent with the specific surface area and XRD test results.

[0136] 7. Catalytic desorption activity test

[0137] Absorption process: CO2 absorption experiments were conducted at 40℃. 80g of a 30% ethanolamine solution was used in each experiment. The catalyst dosage was 0.1wt% of the total ethanolamine solution mass. 99.99% pure CO2 gas was introduced at a flow rate of 200 mL / min for 2 hours.

[0138] Desorption process: The saturated solution was heated using a constant-temperature oil bath, with a regeneration temperature of approximately 80℃. The CO2 concentration in the reactor outlet gas was measured using an online flue gas analyzer. The total amount of CO2 desorbed by the solvent was measured using an online CO2 concentration monitor. To control solution evaporation, a condensation reflux device was installed at the gas outlet.

[0139] The catalysts prepared in Examples 1-6 and Comparative Examples 1-3 were subjected to catalytic desorption activity tests using the methods described above. The test results are as follows: Figure 8 and Figure 9 As shown.

[0140] Depend on Figure 8 It can be seen that, compared with the non-catalytic (blank) conditions, the catalysts prepared in Examples 1-6 can increase the highest CO2 desorption rate by approximately 1.5 to 4 times, exhibiting good catalytic activity. Furthermore, the catalytic activity also varies depending on the annealing temperature. A comparison of the desorption rates in Examples 1 and 5 shows that annealing at 400℃ is the optimal temperature. Annealing at 100℃ makes the MoS2 catalyst crystal structure unstable, resulting in incomplete MoS2 structure growth and a smaller number of active sites, thus significantly reducing the desorption rate.

[0141] Depend on Figure 9 As can be seen, compared with the existing catalysts with better recognized performance (Comparative Examples 1-3), the MoS2 catalyst of Example 1 of the present invention has improved its activity to varying degrees.

[0142] 8. Cyclic stability test

[0143] The catalyst prepared in Example 1 was subjected to a cyclic stability test. The specific test method was as follows: after the catalytic desorption test, the solution was cooled to below 40°C, and the catalytic desorption activity test was repeated. The test results are as follows: Figure 10 As shown.

[0144] Depend on Figure 10 As can be seen in (a), after 8 cycles of testing, the MoS2 catalyst prepared in Example 1 still maintained stable catalytic desorption activity, and the activity did not change significantly. Figure 10As can be seen from (b), the catalyst still maintains a high level of catalytic activity after 10 days of cyclic reaction. Calculated from the total amount of CO2 desorbed, its catalytic activity is still above 95%, which shows that the catalyst prepared in Example 1 has good stability.

[0145] It should be noted that although the technical solution of the present invention has been described with specific examples, those skilled in the art will understand that the present invention should not be limited thereto.

[0146] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or technical improvements to the embodiments in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A method for preparing a transition metal sulfide material for catalytic regeneration and adsorption of carbon dioxide, characterized in that, Includes the following steps: S1: Dissolve the transition metal precursor and the sulfur precursor in water or an alcohol-water mixture, mix them thoroughly, and then add them to the reaction vessel for hydrothermal treatment. S2: The hydrothermally treated material is cleaned and dried with deionized water and anhydrous ethanol, and then annealed to obtain a transition metal sulfide material. Wherein, the transition metal precursor is a salt of a transition metal element, and the molar ratio of the transition metal element to the sulfur element in the sulfur precursor is 1:1 to 1:

16. The transition metal element includes at least one of molybdenum and tungsten.

2. The preparation method according to claim 1, characterized in that, The sulfur precursor includes one or more of thiourea, thioacetamide, and sodium sulfide; and / or, The salts of the transition metal elements include at least one of the chlorides, nitrates, and oxoacids of the transition metal elements.

3. The preparation method according to claim 1 or 2, characterized in that, In step S1, the hydrothermal treatment temperature is 150~180℃, and the hydrothermal treatment time is 24~36h; and / or, In step S1, the volume ratio of alcohol to water in the alcohol-water mixed solvent is 1:1 to 1:10, and the alcohol includes at least one selected from ethanol, ethylene glycol, and isopropanol; and / or, In step S2, the annealing temperature is 100~600℃, and the annealing time is 1~3 hours; and / or, In step S2, the annealing process is carried out under a nitrogen or argon atmosphere.

4. A transition metal sulfide material for catalytic regeneration and adsorption of carbon dioxide, characterized in that, Prepared by the preparation method according to any one of claims 1 to 3 The transition metal sulfide material is a nanosphere-shaped transition metal sulfide, formed by stacking two-dimensional layered transition metal sulfides; the interlayer spacing of the two-dimensional layered structure is 0.62 nm to 0.95 nm; the active center of the transition metal sulfide includes surface acidic sites, which include Li acid sites and Beta acid sites, and the molar ratio of Li acid sites to Beta acid sites is 1:0.5 to 1:

5.

5. The transition metal sulfide material according to claim 4, characterized in that, The transition metal sulfide material contains sulfur vacancy defects, wherein the unsaturated transition metal atoms at the sulfur vacancy defects are bifunctional sites for both L and Brønsted acids.

6. The transition metal sulfide material according to claim 4 or 5, characterized in that, The particle size of the nanosphere transition metal sulfide is 300~600 nm.

7. The transition metal sulfide material according to any one of claims 4 to 6, characterized in that, The transition metal sulfide material has a microporous and / or mesoporous structure; the specific surface area of ​​the transition metal sulfide material is 10 m². 2 The transition metal sulfide material has a pore volume of 0.001 cm³ / g or more. 3 The average pore size of the transition metal sulfide material is 30~40nm, with a density of ≥g.

8. The use of a transition metal sulfide material according to any one of claims 4 to 7, characterized in that, The use of the aforementioned transition metal sulfide materials in the catalytic regeneration of carbon capture amine absorbents and in the carbon dioxide capture and regeneration process.

9. The use according to claim 8, characterized in that, The method for catalytic regeneration of the carbon-capturing amine absorbent includes: adding the transition metal sulfide material to a carbon dioxide-loaded amine-rich absorbent, wherein the amine absorbent includes one or more of monoethanolamine, diethanolamine, methyldiethanolamine, and 2-amino-2-methyl-1-propanol, and under the catalytic action of the transition metal sulfide material, the regeneration temperature of the amine-rich absorbent is 80~110℃, and the carbon dioxide desorption rate is increased by more than 20% in the same time period compared to the condition without a catalyst.

10. The use according to claim 8, characterized in that, The application of the transition metal sulfide material in carbon dioxide capture and regeneration includes: after the transition metal sulfide material is used as a heterogeneous catalyst and circulated in an ethanolamine solution for 10 days, its catalytic activity retention rate is above 95%.

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