Method for preparing medium-high entropy two-dimensional carbide nanomaterials from waste de-nitration catalysts

Abstract

The application discloses a method for preparing medium-high-entropy two-dimensional carbide nanomaterials from waste denitration catalysts. The method comprises the following steps: powdering the waste denitration catalysts; mixing the waste denitration catalyst powder, aluminum oxide powder and graphite powder according to a set molar ratio, adding a PVB binder in the mixing process, and then pressing into a porous block; taking the porous block as a first cathode, taking a graphite electrode as a first anode, and combining with a molten salt electrolyte to form a first electrolysis system; introducing argon as a protective atmosphere into the first electrolysis system, setting the electrolysis temperature and electrolysis voltage of the first electrolysis system to perform electrolysis, and generating a medium-high-entropy MAX ceramic phase in the first cathode through reduction; taking the first cathode generating the medium-high-entropy MAX ceramic phase as a second anode, taking the first anode as a second cathode, combining with a molten salt electrolyte to form a second electrolysis system, setting the electrolysis temperature and electrolysis voltage of the second electrolysis system to perform electrolysis, and performing electrochemical etching on the medium-high-entropy MAX ceramic phase to obtain medium-high-entropy two-dimensional carbide nanomaterials.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of catalyst recovery, and particularly relates to a method for preparing medium-high-entropy two-dimensional carbide nanomaterials from waste denitration catalysts. BACKGROUND

[0002] The main components of the SCR denitration catalyst are titanium dioxide, tungsten trioxide, vanadium pentoxide, etc. For waste denitration catalysts with complete structure, physical and chemical methods can be used for regeneration, and the activity can be restored to 90-100% of that of new catalysts. For damaged waste denitration catalysts, recycling methods must be used for treatment to extract vanadium, tungsten, titanium, molybdenum and other metal resources, turning waste into treasure and turning harm into benefit.

[0003] The existing recovery process mostly uses a wet process or a fire-wet combined recovery process. The wet process or the fire-wet combined recovery process generally uses a large amount of strong acid and strong base to dissolve and separate the waste denitration catalyst. However, the use of a large amount of strong acid and strong base will generate a large amount of acid and alkaline wastewater, causing serious secondary pollution. At the same time, the wet process or the fire-wet combined recovery process is complex and has high energy consumption, and a large amount of carbon emissions will be generated during the entire recovery process. Moreover, the products obtained by the existing process are mostly ammonium metavanadate and TiO2, which are low-value industrial raw materials.

[0004] Two-dimensional carbide MXene is a new type of two-dimensional transition metal carbide, nitride and carbonitride, which has unique electrical conductivity, hydrophilicity, excellent thermal stability, large interlayer spacing, easily adjustable structure and high specific surface area, and has excellent mechanical, electrical, optical and electrochemical properties, showing excellent energy conversion and electrochemical storage potential. It has great application potential in the fields of lithium / sodium ion batteries, supercapacitors, photoelectrocatalysts, solar energy utilization, biological medicine and sensors.

[0005] The Ti, W, V and other elements rich in the waste denitration catalyst are exactly important elements of two-dimensional carbide. Therefore, a new type of clean and short-process recovery process needs to be developed to realize the resource recovery of the waste denitration catalyst and obtain high-value-added products. SUMMARY

[0006] Therefore, some embodiments disclose a method for preparing medium-high-entropy two-dimensional carbide nanomaterials from waste denitration catalysts, which comprises the following steps:

[0007] The waste denitration catalyst is powdered;

[0008] The waste denitration catalyst powder, the alumina powder and the graphite powder are mixed according to a set molar ratio, and a set molar fraction of PVB binder is added during the mixing process. The mixture is pressed into a porous block under a set pressure.

[0009] The porous block is used as a first cathode, the graphite electrode is used as a first anode, and a first electrolysis system is formed together with a molten salt electrolyte;

[0010] Argon gas is introduced into the first electrolysis system as a protective atmosphere, and electrolysis is performed by setting the electrolysis temperature and electrolysis voltage of the first electrolysis system, and a medium-high-entropy MAX ceramic phase is generated by reduction of the first cathode; the total reaction formula is:

[0011] 6MeO x + Al2O3 + (6x+7)C = 2Me3AlC2 + (6x+3)CO;

[0012] wherein MeO x represents a metal oxide in the denitration catalyst;

[0013] The first cathode for generating the medium-high-entropy MAX ceramic phase is used as a second anode, the first anode is used as a second cathode, and a second electrolysis system is formed together with a molten salt electrolyte;

[0014] Electrolysis is performed by setting the electrolysis temperature and electrolysis voltage of the second electrolysis system, and electrochemical etching of the medium-high-entropy MAX ceramic phase is performed to obtain a medium-high-entropy two-dimensional carbide nanomaterial.

[0015] Some embodiments disclose a method for preparing a medium-high-entropy two-dimensional carbide nanomaterial from a waste denitration catalyst, and the molar ratio of the waste denitration catalyst powder, the aluminum oxide powder and the graphite powder is 3:1:2-4.

[0016] Some embodiments disclose a method for preparing a medium-high-entropy two-dimensional carbide nanomaterial from a waste denitration catalyst, and the molar fraction of the PVB binder is 2-20%.

[0017] Some embodiments disclose a method for preparing a medium-high-entropy two-dimensional carbide nanomaterial from a waste denitration catalyst, and the pressing pressure is 10-80 MPa.

[0018] Some embodiments disclose a method for preparing a medium-high-entropy two-dimensional carbide nanomaterial from a waste denitration catalyst, and the molten salt electrolyte is a mixture of LiCl-KCl, LiCl-NaCl and LiCl-NaCl-NaF.

[0019] Some embodiments disclose a method for preparing a medium-high-entropy two-dimensional carbide nanomaterial from a waste denitration catalyst, and the ratio of the total amount of LiCl-KCl and LiCl-NaCl to LiCl-NaCl-NaF is 3:2-1, and the molar content of fluorine ions is 1-8% of the total amount of the molten salt electrolyte.

[0020] Some embodiments disclose a method for preparing a medium-high-entropy two-dimensional carbide nanomaterial from a waste denitration catalyst, and the electrolysis temperature of the first electrolysis system is 450-650℃.

[0021] The method for preparing medium-high entropy two-dimensional carbide nanomaterials from waste denitration catalysts disclosed by some embodiments has an electrolysis voltage of 2.9-4V in the first electrolysis system.

[0022] The method for preparing medium-high entropy two-dimensional carbide nanomaterials from waste denitration catalysts disclosed by some embodiments has an electrolysis temperature of 450-650℃ in the second electrolysis system.

[0023] The method for preparing medium-high entropy two-dimensional carbide nanomaterials from waste denitration catalysts disclosed by some embodiments has an electrolysis voltage of 1.2-2.6V in the second electrolysis system.

[0024] The method for preparing medium-high entropy two-dimensional carbide nanomaterials from waste denitration catalysts disclosed by the embodiments of the present application comprises the following steps: powderizing the waste denitration catalyst, mixing the powderized waste denitration catalyst with aluminum oxide and graphite, and pressing the mixture to form a solid-state electrode. The solid-state electrode is first used as a cathode to perform electrolytic reduction in a lithium-based chloride molten salt, and then used as an anode to perform electrochemical etching and intercalation, thereby obtaining medium-high entropy two-dimensional carbides. The method for preparing medium-high entropy two-dimensional carbide nanomaterials from waste denitration catalysts disclosed by the embodiments of the present application has a simple process flow, easy-to-control process conditions, and is easy to operate. The method can realize efficient conversion and recovery of metal oxides in waste denitration catalysts, and can obtain high-value-added products. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 Electrolysis process schematic diagram for preparing medium-high entropy two-dimensional carbide nanomaterials from waste denitration catalysts;

[0026] Figure 2 XRD pattern of medium-high entropy MAX ceramic phase in Example 1;

[0027] Figure 3 SEM pattern of medium-high entropy MAX ceramic phase in Example 2;

[0028] Figure 4 SEM pattern of medium-high entropy MAX ceramic phase in Example 3;

[0029] Figure 5 XPS pattern of medium-high entropy two-dimensional carbide nanomaterials in Example 4. DETAILED DESCRIPTION

[0030] The term "embodiment" is used herein in a non-limiting sense as "exemplary." Performance index tests in the embodiments of the present application are performed by using conventional test methods in the art, unless otherwise specified. It should be understood that the terms used in the present application are merely used to describe specific embodiments, and are not intended to limit the disclosure of the present application.

[0031] Unless otherwise indicated, the technical and scientific terms used herein have the same meaning as those commonly understood by one of ordinary skill in the art to which this application belongs; the term "consisting of" is used in its conventional sense to specify that the listed steps are to be followed, but does not imply that additional steps can not be utilized; the term "consisting essentially of" is used in its conventional sense to specify that additional steps can be utilized, but that the additional steps do not materially change the basic and novel characteristics of the application; the term "comprising" is used in its conventional sense, including ongoing art-recognized equivalents such as "including," "having," "containing," "involving," "denoting," or the like; the term "comprise," "comprises," and "comprised of" as used herein are synonymous with "comprising" and are used in the sense of the open-ended term "comprising," and are not intended, nor used, in the sense of the closed term "consisting of."

[0032] The terms "substantial" and "about" are used herein to describe small fluctuations. For example, they can mean less than or equal to ± 5%, such as less than or equal to ± 2%, such as less than or equal to ± 1%, such as less than or equal to ± 0.5%, such as less than or equal to ± 0.2%, such as less than or equal to ± 0.1%, such as less than or equal to ± 0.05%. Numerical data may, in some instances, be presented in a range format. It is to be understood that such a range format is used only for convenience and brevity and should be taken as a literal disclosure of a range. For example, a numerical range of "1 to 5" should be interpreted to include not only the explicitly stated values of "1 to 5", but also the range of values starting from the lower and up to the upper value, as incrementally increments the minimum value by 1 and the maximum value by 1. Accordingly, the range of values includes individual values such as 2, 3.5, and 4, and sub-ranges such as 1 to 3, 2 to 4, and 3 to 5, etc. This same principle applies to ranges reciting only one numerical value. Furthermore, such an interpretation should apply regardless of the breadth of the range or the characteristics being described.

[0033] In this document, including in the claims, the conjunctions, such as "comprising," "including," "containing," "having," "involving," "denoting," "accommodating," and the like are to be understood as open-ended, i.e., meaning "including, but not limited to." Only the conjunctions "consisting of" and "consisting essentially of" are closed conjunctions.

[0034] In order to facilitate a better understanding of the present application, numerous specific details are given in the detailed description below. One skilled in the art will understand, however, that the application can be practiced without certain specific details. In instances, methods, means, instruments, devices, etc. that are well known to those skilled in the art are not described in detail in order to avoid obscuring the subject matter of the present application.

[0035] Without conflict, the technical features disclosed in the embodiments of this application can be combined arbitrarily, and the resulting technical solutions belong to the content disclosed in the embodiments of this application. It should be noted that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer" used in this application indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing technical features and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention unless they conflict with the context. In addition, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance unless they conflict with the context.

[0036] Medium-entropy carbides refer to a type of composite material whose entropy value, i.e., the degree of disorder of the material, is between that of ordinary carbides and high-entropy carbides. Their entropy value is usually 2 to 5, and they are made up of several elements mixed in a certain proportion; the entropy value of high-entropy carbides is greater than 5.

[0037] Because denitrification catalysts vary slightly from manufacturer to manufacturer and brand to brand, spent denitrification catalysts are often rich in more than three transition metal elements. Therefore, two-dimensional carbides prepared from spent denitrification catalysts can be classified as medium-entropy carbides or high-entropy carbides. Various modern characterization methods such as EDS and XRD are often used to determine whether the phase composition of medium-entropy or high-entropy carbides is singular and whether the element distribution is uniform.

[0038] In some embodiments, methods for preparing high-entropy two-dimensional carbide nanomaterials by recycling spent denitrification catalysts include:

[0039] Waste denitrification catalyst is pulverized; generally, the waste denitrification catalyst is first cleaned with negative pressure and rinsed with clean water, and then the cleaned waste denitrification catalyst is dried, crushed and ground into uniform powder.

[0040] Waste denitrification catalyst powder, alumina powder, and graphite powder are mixed in a set molar ratio. During the mixing process, a set molar fraction of PVB binder is added, and then the mixture is pressed into a porous block under a set pressure. The addition of PVB binder can make the waste denitrification catalyst powder, alumina powder, and graphite powder bond more firmly, making the porous block more robust and suitable for subsequent use.

[0041] like Figure 1 As shown, switch 1 is connected, with a porous block as the first cathode and a graphite electrode as the first anode, forming a first electrolysis system with a mixture of molten salt electrolytes LiCl-KCl, LiCl-NaCl and LiCl-NaCl-NaF;

[0042] The argon gas is introduced into the first electrolysis system as a protective atmosphere, and the electrolysis temperature of the first electrolysis system is set to 450-650 DEG C, and the electrolysis voltage is 2.9-4V; the electrolysis temperature and the electrolysis voltage affect the thermodynamic and kinetic conditions of the whole reaction, the higher the temperature and the greater the voltage, the greater the driving force of the reaction, the faster and more sufficient the electrolysis reaction, the better the cathode oxygen removal effect, and the more conducive to the synthesis of the medium-high-entropy MAX ceramic phase; at the same time, since the whole reduction and carbonization reaction occurs in the cathode, it has the protection of the cathode current, and the reaction temperature is controlled below 650 DEG C, which can avoid the loss of volatile phases such as MoO3 and WO3 in the porous block, and the loss of metal elements such as Ti, W and V will not occur;

[0043] The first cathode reduction generates a medium-high-entropy MAX ceramic phase, and the first anode generates an oxidation reaction to generate O2 / CO / CO2;

[0044] The total reaction is as follows:

[0045] 6MeO x +Al2O3+(6x+7)C=2Me3AlC2+(6x+3)CO;

[0046] Wherein, MeO x represents a metal oxide in the denitration catalyst;

[0047] Wherein, the cathode is the deoxidation of MeO x , Al2O3 and carbonization, and the anode is the oxidation process of O 2- ion; MeO x represents a metal oxide in the denitration catalyst, including MoO3, WO3, etc.;

[0048] After the electrolysis reaction of the first electrolysis system is completed, the switch 1 is disconnected, and the switch 2 is connected, so that the first cathode for generating a medium-high-entropy MAX ceramic phase is used as the second anode, and the first anode is used as the second cathode, and a second electrolysis system is formed with a molten salt electrolyte;

[0049] The electrolysis temperature of the second electrolysis system is set to 450-650 DEG C, and the electrolysis voltage is 1.2-2.6V, and the electrolysis temperature and the electrolysis voltage affect the thermodynamic and kinetic conditions of the whole reaction, the higher the temperature and the greater the voltage, the greater the driving force of the reaction, and the reaction is faster and more sufficient;

[0050] During the electrolysis process, the medium-high-entropy MAX ceramic phase is electrochemically etched to obtain a medium-high-entropy two-dimensional carbide nanomaterial with a graphene-like structure, and the material is solid-solubilized with Ti, V, W and other multi-metal phases; usually after the electrolysis is completed, the prepared medium-high-entropy two-dimensional carbide nanomaterial needs to be repeatedly washed with deionized water, and dehydrated and dried by a freeze dryer.

[0051] In the electrolysis process, aluminum is more reactive than carbide, and the potential required for oxidation in the same electrolyte is lower, so aluminum in the medium-high entropy MAX ceramic phase is preferentially oxidized and released into the molten salt in the form of ions: Al = Al 3+ + 3e - A large number of intermediate layer gaps appear in the sandwich structure of the medium-high entropy MAX ceramic phase; at the same time, lithium ions in the molten salt diffuse into the intermediate layer gaps of the medium-high entropy MAX ceramic phase due to their small radius, filling the medium-high entropy MAX ceramic phase, thereby avoiding problems such as agglomeration of the two-dimensional structure; however, if the reaction temperature is too high, the oxidation potential of the carbide will be reached, and elements such as Al and Ti will be co-deposited, resulting in a change from two-dimensional carbide to amorphous porous carbon material: TiC = Ti n+ + ne - Therefore, the upper limit of the reaction temperature of the electrolysis reaction is controlled to be 650℃.

[0052] In some embodiments, the molar ratio of the waste denitration catalyst powder, the aluminum oxide powder, and the graphite powder is 3:1:2-4.

[0053] In some embodiments, the molar fraction of the PVB binder is 2-20%.

[0054] In some embodiments, the pressing pressure is 10-80 MPa.

[0055] In some embodiments, the molten salt electrolyte is a mixture of LiCl-KCl, LiCl-NaCl, and LiCl-NaCl-NaF; using two or more molten salts can not only reduce the melting point through eutectic reaction, but also adjust the physicochemical properties of the molten salt, and the synthesis of the medium-high entropy MAX ceramic phase requires the dissolution and diffusion of oxygen ions in the molten salt, so the mixture of LiCl-KCl, LiCl-NaCl, and LiCl-NaCl-NaF as the molten salt electrolyte is beneficial to the dissolution and diffusion of oxygen ions; when a large number of intermediate layer gaps appear in the electrochemical etching of the medium-high entropy MAX ceramic phase, lithium ions can diffuse into these intermediate layer gaps due to their small radius, so the LiCl-based molten salt is used in the embodiments of the present application.

[0056] In some embodiments, the total amount of LiCl-KCl and LiCl-NaCl to LiCl-NaCl-NaF is in the ratio of 3:2-1, and the molar content of fluorine ions is 1-8% of the total amount of the molten salt electrolyte.

[0057] The technical details are further exemplarily described below in conjunction with the embodiments.

[0058] Embodiment 1

[0059] Figure 2XRD pattern of the medium-high-entropy MAX ceramic phase disclosed in Example 1.

[0060] The method for preparing the medium-high-entropy two-dimensional carbide nanomaterial disclosed in Example 1 comprises:

[0061] The waste denitration catalyst is powdered;

[0062] 1 g of the waste denitration catalyst powder is weighed out, mixed with aluminum oxide and graphite powder at a molar ratio of 3:1:4, a molar fraction of 10% of PVB binder is added during the mixing process, and then a porous block is pressed under a pressure of 10 MPa;

[0063] The porous block is used as a first cathode, a graphite electrode is used as a first anode, and a first electrolysis system is formed with a molten salt electrolyte;

[0064] Argon gas is introduced into the first electrolysis system as a protective atmosphere, the electrolysis temperature is set to 500°C, the electrolysis voltage is set to 3V, and electrolysis is performed for 6h, and the first cathode is reduced to generate a medium-high-entropy MAX ceramic phase, as shown in Figure 2 , which presents typical Ti3AlC2 phase diffraction peaks, and no other phases are found, confirming the successful synthesis of the medium-high-entropy MAX phase;

[0065] The first cathode generating the medium-high-entropy MAX ceramic phase is used as a second anode, the first anode is used as a second cathode, and a second electrolysis system is formed with a molten salt electrolyte;

[0066] The electrolysis voltage is adjusted to 2V, and electrolysis is performed for 6h, and the medium-high-entropy MAX ceramic phase is electrochemically etched to remove aluminum;

[0067] After cooling after electrolysis is completed, the second anode is taken out, repeatedly washed with deionized water, and then dehydrated with a freeze dryer to obtain a medium-high-entropy two-dimensional carbide nanomaterial.

[0068] Example 2

[0069] Figure 3 SEM image of the medium-high-entropy MAX ceramic phase disclosed in Example 2.

[0070] The method for preparing the medium-high-entropy two-dimensional carbide nanomaterial disclosed in Example 2 comprises:

[0071] The waste denitration catalyst is powdered;

[0072] 2 g of the waste denitration catalyst powder is weighed out, mixed with aluminum oxide and graphite powder at a molar ratio of 3:1:2, a molar fraction of 15% of PVB binder is added during the mixing process, and then a porous block is pressed under a pressure of 200 MPa;

[0073] The porous block is used as a first cathode, the graphite electrode is used as a first anode, and a molten salt electrolyte is used to form a first electrolysis system;

[0074] Argon gas is introduced into the first electrolysis system as a protective atmosphere, the electrolysis temperature is set to 550 DEG C, the electrolysis voltage is set to 4V, and electrolysis is performed for 6h. The first cathode is reduced to generate a medium-high-entropy MAX ceramic phase as shown in Figure 3 ;

[0075] The first cathode generating the medium-high-entropy MAX ceramic phase is used as a second anode, the first anode is used as a second cathode, and a molten salt electrolyte is used to form a second electrolysis system;

[0076] The electrolysis voltage is adjusted to 2.1V, and electrolysis is performed for 4h. The medium-high-entropy MAX ceramic phase is electrochemically etched to remove aluminum;

[0077] After cooling after electrolysis is completed, the second anode is taken out, repeatedly washed with deionized water, and then dehydrated with a freeze dryer to obtain a medium-high-entropy two-dimensional carbide nanomaterial.

[0078] Example 3

[0079] Figure 4 The SEM image of the medium-high-entropy MAX ceramic phase disclosed in Example 3.

[0080] The method for preparing a medium-high-entropy two-dimensional carbide nanomaterial from a waste denitration catalyst disclosed in this example 3 comprises:

[0081] The waste denitration catalyst is powdered;

[0082] 1.5g of the waste denitration catalyst powder is weighed, mixed with aluminum oxide and graphite powder at a molar ratio of 3:1:3.5, a molar fraction of 5% PVB binder is added during the mixing process, and then a porous block is pressed under a pressure of 50MPa;

[0083] The porous block is used as a first cathode, the graphite electrode is used as a first anode, and a molten salt electrolyte is used to form a first electrolysis system;

[0084] Argon gas is introduced into the first electrolysis system as a protective atmosphere, the electrolysis temperature is set to 600 DEG C, the electrolysis voltage is set to 3.3V, and electrolysis is performed for 8h. The first cathode is reduced to generate a medium-high-entropy MAX ceramic phase as shown in Figure 4 ;

[0085] The first cathode generating the medium-high-entropy MAX ceramic phase is used as a second anode, the first anode is used as a second cathode, and a molten salt electrolyte is used to form a second electrolysis system;

[0086] The electrolysis voltage is adjusted to 2.4V, and electrolysis is performed for 5h. The medium-high-entropy MAX ceramic phase is electrochemically etched to remove aluminum;

[0087] After electrolysis is completed and cooled, the second anode is taken out, repeatedly washed with deionized water, and then dehydrated with a freeze dryer to obtain the medium-high-entropy two-dimensional carbide nanomaterial.

[0088] Example 4

[0089] Figure 5 XPS chart of the medium-high-entropy two-dimensional carbide nanomaterial disclosed in Example 4.

[0090] The method for preparing the medium-high-entropy two-dimensional carbide nanomaterial from the waste denitration catalyst disclosed in Example 4 comprises:

[0091] The waste denitration catalyst is powdered;

[0092] 3g of the waste denitration catalyst powder is weighed, mixed with aluminum oxide and graphite powder at a molar ratio of 3:1:4, a molar fraction of 20% PVB binder is added during the mixing process, and then a porous block is pressed under a pressure of 30MPa;

[0093] The porous block is used as the first cathode, the graphite electrode is used as the first anode, and a first electrolysis system is formed with a molten salt electrolyte;

[0094] Argon gas is introduced into the first electrolysis system as a protective atmosphere, the electrolysis temperature is set to 550℃, the electrolysis voltage is set to 3.8V, electrolysis is performed for 7h, and the medium-high-entropy MAX ceramic phase is generated by reduction of the first cathode;

[0095] The first cathode generating the medium-high-entropy MAX ceramic phase is used as the second anode, the first anode is used as the second cathode, and a second electrolysis system is formed with a molten salt electrolyte;

[0096] The electrolysis voltage is adjusted to 2.2V, and electrolysis is performed for 5h, and the medium-high-entropy MAX ceramic phase is electrochemically etched to remove aluminum;

[0097] After electrolysis is completed and cooled, the second anode is taken out, repeatedly washed with deionized water, and then dehydrated with a freeze dryer to obtain the medium-high-entropy two-dimensional carbide nanomaterial.

[0098] The medium-high-entropy two-dimensional carbide nanomaterial prepared in Example 4 is subjected to XPS detection, and the detection results are shown in Figure 5 The binding energy spectrum of 281-282eV typical transition metal carbide is shown in the C1s high-resolution XPS spectrum, confirming that the product exists in the form of carbide.

[0099] The method for preparing medium-high-entropy two-dimensional carbide nanomaterials from waste denitration catalysts disclosed in the embodiments of the present application comprises the following steps: powderizing the waste denitration catalyst, mixing the powderized waste denitration catalyst with alumina and graphite, briquetting to form a solid-state electrode, and electrolytic reduction as a cathode in a lithium-based chloride molten salt, and then electrochemical etching and intercalation as an anode, to obtain medium-high-entropy two-dimensional carbides. The method for preparing medium-high-entropy two-dimensional carbide nanomaterials from waste denitration catalysts disclosed in the embodiments of the present application has a simple process flow, easy-to-control process conditions, and is easy to operate, can realize high-efficiency conversion and recovery of metal oxides in waste denitration catalysts, and can obtain high-value-added products.

[0100] The technical details disclosed in the technical solutions and embodiments of the present application are only exemplary to illustrate the inventive concept of the present application, and do not constitute a limitation on the technical solutions of the present application. Any conventional changes, substitutions or combinations of the technical details disclosed in the embodiments of the present application all have the same inventive concept as the present application, and are within the protection scope of the claims of the present application.

Claims

1. A method for preparing a medium-high entropy two-dimensional carbide nanomaterial from waste de-NOx catalysts, characterized in that, The application relates to a method for preparing a high-entropy two-dimensional carbide nanomaterial. The waste denitration catalyst is powdered; The waste denitration catalyst powder, alumina powder and graphite powder are mixed in a set molar ratio of 3:1:2-4, and a set molar fraction of PVB binder is added in the mixing process; and the porous block is pressed under a set pressure; The porous block is used as a first cathode, the graphite electrode is used as a first anode, and a first electrolysis system is formed by the first cathode, the first anode and a molten salt electrolyte; the molten salt electrolyte is a mixture of LiCl-KCl, LiCl-NaCl and LiCl-NaCl-NaF, the total amount of the LiCl-KCl and the LiCl-NaCl and the LiCl-NaCl-NaF are in a ratio of 3:2-1, and the molar content of fluorine ions is 1-8% of the total molar amount of the molten salt electrolyte; Argon is introduced into the first electrolysis system as a protective atmosphere, the electrolysis temperature of the first electrolysis system is set to be 450-650 DEG C, the electrolysis voltage is set to be 2.9-4 V, electrolysis is carried out, the first cathode is reduced to generate a medium-high-entropy MAX ceramic phase, and the total reaction formula is as follows: 6MeO x + AI2O3 + (6x + 7)C = 2Me3AlC2 + (6x + 3)CO; wherein MeO x represents a metal oxide in the denitration catalyst; The first cathode generating the medium-high-entropy MAX ceramic phase is used as a second anode, the first anode is used as a second cathode, and a second electrolysis system is formed by the second anode, the second cathode and the molten salt electrolyte; The electrolysis temperature of the second electrolysis system is set to be 450-650 DEG C, the electrolysis voltage is set to be 1.2-2.6 V, electrolysis is carried out, the medium-high-entropy MAX ceramic phase is electrochemically etched, and a medium-high-entropy two-dimensional carbide nanomaterial is obtained.

2. The method for preparing middle-high-entropy two-dimensional carbide nanomaterials from waste de-NOx catalysts according to claim 1, characterized in that, The molar fraction of the PVB binder is 2-20%.

3. The method of claim 1, wherein the method is characterized by: The pressing pressure is 10-80 MPa.

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