Metal oxide supported metal catalyst configuration, application, construction and preparation method

Abstract

The invention relates to the field of preparation of green chemical nano materials, in particular to a metal oxide supported metal catalyst configuration, application, construction and a preparation method. The invention relates to a metal oxide supported metal catalyst configuration, which is characterized in that the configuration comprises Pd4 / gamma-Al2O3 (110), Au4 / gamma-Al2O3 (110), Pd3Au1a / gamma-Al2O3 (110), Pd2Au2e / gamma-Al2O3 (110) and Pd1Au3b / gamma-Al2O3 (110). According to the method, closed-loop optimization is verified through theoretical simulation and experiments, a full-chain research normal form of structural design-dynamic evolution-performance output is established, and cross-scale theoretical and experimental support is provided for precise regulation and controllable synthesis of atomic scale and efficient application of the atomic scale in one-step oxidation esterification reaction of aldol.

Description

Technical Field

[0001] The present invention relates to the field of green chemical nanomaterial preparation, in particular to the field of constructing a series of catalyst models - high-throughput screening - experimental precision preparation technology, and specifically to a metal oxide-supported metal catalyst configuration, application, construction and preparation method. Background Art

[0002] In recent years, with the increasing awareness of environmental protection and the popularization of green chemistry concepts, the demand for environmentally friendly chemical processes has been growing. Methyl methacrylate (MMA), an important chemical raw material, is widely used in the manufacture of products such as organic glass, coatings, and adhesives. Traditional MMA production processes typically involve multi-step reactions, are energy-intensive, and produce a large number of byproducts, placing a significant burden on the environment. Therefore, the development of an efficient and green one-pot synthesis process for MMA has become a research hotspot.

[0003] A novel one-step oxidative esterification method for methacrolein (MAL) with methanol to prepare MMA has attracted widespread attention due to its remarkable environmental friendliness. However, the successful implementation of this process is highly dependent on the design and optimization of the catalyst. Current research focuses on improving the activity, selectivity, and stability of the catalyst to address core issues such as byproduct suppression and metal deactivation. By regulating "metal-support electronic modulation", new catalytic materials can be provided for the one-step oxidative esterification reaction of alcohol-aldehydes. Despite this, experimental characterization methods still face challenges in identifying and quantitatively describing the active sites.

[0004] In this context, quantum chemical computational methods, especially density functional theory (DFT), have gradually become important tools for designing and guiding surface chemical reactions. These computational methods can predict the stability and activity of different catalyst structures, thereby guiding experimental design. However, combining theoretical calculations with experimental verification to establish a full-chain research paradigm from the molecular level to macroscopic performance is crucial for achieving precise regulation and controllable synthesis at the atomic scale.

[0005] In the field of catalyst design, high-throughput screening technology can identify the optimal catalyst with specific properties by rapidly testing a large number of candidate materials. This method greatly improves the efficiency and speed of new material discovery, and is particularly important in the search for efficient metal oxide-supported mono- or bimetallic catalysts.

[0006] At the same time, if the configuration of the catalyst is not properly designed, it will lead to a series of problems such as low catalytic activity, poor selectivity, insufficient stability and low resource utilization efficiency. Specifically, inappropriate metal combinations and structures will weaken the catalyst's ability to promote the conversion of methacrolein (MAL) to methyl methacrylate (MMA), reducing the reaction rate and conversion efficiency; at the same time, the wrong configuration may lead to an increase in side reactions, reduce the selectivity of the target product, and cause unnecessary by-products to be generated, increasing the difficulty and cost of subsequent processing. In addition, an undesirable configuration may also make the catalyst easily deactivated or aggregated under actual operating conditions, shortening its service life and increasing production costs. More importantly, the failure to find the optimal palladium-gold ratio and its distribution will lead to inefficient use of precious metals, which not only increases the economic burden but is also not conducive to sustainable development.

[0007] Therefore, by accurately screening specific configurations, the performance of the catalyst can be effectively improved to ensure its efficient and stable operation. Summary of the Invention

[0008] (1) Technical issues to be resolved

[0009] In view of the above-mentioned shortcomings and deficiencies of the prior art, the present invention provides a metal oxide-supported metal catalyst configuration, application, construction and preparation method, which solves the technical problems such as low catalytic activity, poor selectivity and insufficient stability caused by improper configuration design.

[0010] (2) Technical solution

[0011] In order to achieve the above-mentioned objectives, the main technical solutions adopted by the present invention include: in the first aspect, the present invention provides a metal oxide-supported metal catalyst configuration, which includes: Pd4 / γ-Al2O3(110), Au4 / γ-Al2O3(110), Pd3Au1a / γ-Al2O3(110), Pd2Au2e / γ-Al2O3(110) and Pd1Au3b / γ-Al2O3(110).

[0012] In a second aspect, the present invention provides a method for constructing a metal oxide-supported metal catalyst configuration, comprising the following steps:

[0013] Step S1: constructing the carrier γ-type aluminum oxide crystal surface

[0014] A γ-Al2O3(110) crystal plane model was constructed in molecular simulation software, multilayer thickness was set, and a vacuum layer was added to avoid the influence of periodic boundary conditions.

[0015] Step S2: Constructing a single metal palladium cluster

[0016] Pd clusters with different atomic numbers were designed, including Pd1, Pd2, Pd3 and Pd4. The clusters Pd1, Pd2, Pd3 and Pd4 were placed on the surface of the carrier γ-Al2O3(110), and a stable catalyst configuration was found through optimization. After optimization, the catalyst configuration obtained was Pd4 / γ-Al2O3(110);

[0017] Step S3: Constructing a single metal gold cluster

[0018] Au clusters with different numbers of atoms were designed, including Au1, Au2, Au3 and Au4. Clusters Au1, Au2, Au3 and Au4 were placed on the surface of the carrier γ-Al2O3(110), and a stable catalyst configuration was found through optimization. After optimization, the catalyst configuration obtained was Au4 / γ-Al2O3(110);

[0019] Step S4: Constructing a bimetallic palladium-gold cluster

[0020] Pd-Au clusters with different atomic numbers and configurations were designed, including Pd3Au1, Pd2Au2, and Pd1Au3. The clusters Pd3Au1, Pd2Au2, and Pd1Au3 were placed on the surface of the carrier γ-Al2O3(110), and stable catalyst configurations were found through optimization. After optimization, the configurations obtained were Pd3Au1a / γ-Al2O3(110), Pd2Au2e / γ-Al2O3(110), and Pd1Au3b / γ-Al2O3(110).

[0021] Step S5: Configuration evaluation

[0022] The binding energy, adsorption energy and / or bond energy of each configuration in steps S2, S3 and S4 were calculated, and the interaction strength between the support γ-Al2O3(110) and monometallic Pd, monometallic Au and bimetallic Pd-Au was investigated to evaluate the stability and catalytic performance of each catalyst configuration.

[0023] In some embodiments, in step S1, the exposed surface of γ-alumina (γ-Al2O3) is 83%, the number of layers is 10 to 13, and the size of each layer is The vacuum layer is

[0024] Preferably, the number of layers is 12, and the size of each layer is The vacuum layer is

[0025] In some embodiments, in step S5, the evaluation index includes the binding energy E of the metal clusters. bind (M n ) to evaluate the stability of metal clusters. The stability of metal clusters increases with Ebind (M n ) increases and increases;

[0026] Formula (1) is: E bind (M n )=[n×E(M)-E(M n )] / n, in formula (1), E(M n ) is the energy of the metal cluster, E(M) is the energy of a single metal, and n is the number of metal atoms.

[0027] E bind (M n ) is larger, the more stable the metal cluster is, and E(M n ) is smaller, the energy required to form clusters is lower and the clusters are more stable.

[0028] The larger E(M) is, the more unstable the individual metal atoms become, which in turn prompts them to combine to form clusters, indirectly making the clusters more stable.

[0029] In some embodiments, in step S5, the evaluation index includes the bond energy E between the metal cluster and the carrier. bind (M n / S) to evaluate the stability of the supported catalyst. The stability of the supported catalyst increases with the increase of E bind (M n / S) increases with the increase;

[0030] Formula (2) is: E bind (M n / S)=[n×E(M n )+E(S)-E(M n / S)] / n, in formula (2), E(M n / S) is the energy of metal clusters loaded on the carrier, E(M n ) is the energy of the metal cluster, E(S) is the energy of the carrier, and n is the number of metal atoms.

[0031] E(M n / S) value is larger, the total energy after the metal clusters and the carrier are combined is higher, the total energy after the metal clusters and the carrier are combined is higher, the combination is not so tight, and the stability is lower.

[0032] The larger the E(S) value is, the higher the energy state of the carrier itself is, the more unstable the carrier itself is, and the easier it is to form clusters.

[0033] In some embodiments, in step S5, the evaluation index includes the adsorption energy E of the metal cluster loaded on the carrier. ads (M n / S) to evaluate the interaction strength between the metal clusters and the support and its effect on the stability of the supported catalyst; the greater the adsorption energy between the metal clusters and the support, the more stable the supported catalyst.

[0034] Formula (3a) is:

[0035] E ads (M n / S)=E(M n )+E(S)-E(M n / S), in formula (3a), E(M n / S) is the energy of metal clusters loaded on the carrier, E(M n ) is the energy of the metal cluster, and E(S) is the energy of the carrier;

[0036] or,

[0037] Formula (3b) is:

[0038] E ads (M n / S)=E def (M n )+E def (S)+E int , where E def (M n ) is the deformation energy of the metal cluster, E def (S) is the deformation energy of the carrier, E int is the interaction energy between metal clusters and supports.

[0039] E def (M n ) parameter is the energy required to change geometric parameters such as interatomic distances and angles within a metal cluster when it transitions from a free state to an adsorbed state. If the metal cluster needs to deform to adapt to the support surface, additional energy is required, resulting in a positive deformation energy. Conversely, if the adsorption process stabilizes the metal cluster, energy is released, resulting in a negative deformation energy.

[0040] E def The (S) parameter is the energy required for the structural change caused by the adsorption of metal clusters. To accommodate the metal clusters, the carrier needs to change its lattice constant or other local structural characteristics. The energy required for this structural adjustment is the deformation energy of the carrier.

[0041] E intThis refers to the direct interaction energy between the metal cluster and the support, including all forms of interaction such as chemical bonding, electrostatic interactions, and van der Waals forces. It is an important indicator of the strength of the bond between the two. A larger interaction energy indicates a stronger bond between the metal cluster and the support, which generally also means greater stability.

[0042] By analyzing these energy terms, we can better understand how metal clusters interact with their supports and optimize catalyst design for optimal performance. For example, by modifying deformation energy or interaction energy, the overall stability of supported catalysts can be improved. Furthermore, these energy data provide an important basis for theoretical simulations, helping to predict and interpret experimental results.

[0043] In some embodiments, in formula (3b), the adsorption energy E of the metal cluster loaded on the carrier is ads (M n / S) can be decomposed into deformation energy, which includes the deformation energy E of the metal cluster. def (M n ) and the deformation energy E of the carrier def (S);

[0044] Formula (4) is:

[0045] E def (M n )=E(M n )-E(M' n ), where E(M n ) is the energy of the metal cluster, E(M n ′) is the energy of the adsorbed cluster;

[0046] Formula (5) is:

[0047] E def (S)=E(S)-E(S'), where E(S) is the energy of the carrier and E(S') is the energy of the carrier in the adsorbed state.

[0048] In some embodiments, in formula (3b), the adsorption energy E of the metal cluster loaded on the carrier is ads (M n / S) can be decomposed into the interaction energy E between the metal clusters and the support int ;

[0049] Formula (6) is:

[0050] E int =E(M' n )+E(S')-E(M n / S), where E(M n′) is the energy of the adsorbed cluster, E(S′) is the energy of the adsorbed carrier, E(M n / S) is the energy of metal clusters loaded on the carrier.

[0051] In a third aspect, the present invention provides an application of the above-mentioned configuration, or the configuration constructed by the above-mentioned construction method, in the one-step oxidative esterification reaction of methacrolein and methanol for preparing methyl methacrylate.

[0052] In a fourth aspect, the present invention provides a method for preparing a γ-alumina-supported bimetallic palladium-gold catalyst having a configuration of Pd2Au2e / γ-Al2O3, comprising the steps of: 1. weighing 3-5 parts of γ-Al2O3, adding the catalyst to 100-105 parts of water, and performing ultrasonic treatment to disperse the carrier;

[0053] Step 2: Add 0.063-0.065 parts of HAuCl4 and 0.842-0.845 parts of urea to the solution in step 1, and add 12.0-12.5 parts of a PdCl2 solution having a concentration of 14.2-14.5 mmol / L and 193.5-195 parts of water;

[0054] Step 3: Heat the mixture in step 2 in a water bath for 8-10 hours while vigorously stirring. After stopping heating, wash with deionized water until the precipitate cannot be detected by 0.5 mol / L AgNO3. Then, dry at 80-90°C for 12-15 hours and perform a reduction reaction to obtain the product Pd2Au2e / γ-Al2O3.

[0055] (3) Beneficial effects

[0056] This invention establishes a full-chain research paradigm of "structural design-dynamic evolution-performance output" through theoretical simulation and experimental verification of closed-loop optimization, providing cross-scale theoretical and experimental support for precise regulation and controllable synthesis at the atomic scale and its efficient application in the one-step oxidative esterification reaction of alcohols and aldehydes.

[0057] Experiments have shown that the γ-alumina-supported bimetallic palladium-gold catalyst can promote the conversion of methacrolein and improve the selectivity of methyl methacrylate. The method of the present invention is simple to operate, low in cost, and can achieve the goal of precise control.

[0058] The evaluation includes the bond length D between metal atoms M-M By precisely controlling the bond length D between metal atoms M-M , can optimize the electronic structure within the metal cluster and between the metal cluster and the support, thereby improving the adsorption and conversion efficiency of the target reactants. Optimized bond lengths help form more stable active sites, thereby improving overall catalytic activity.

[0059] Rational design of the microstructure of metal clusters, including adjusting their distribution on the carrier, can effectively reduce the formation of by-products, improve the selectivity of target products, and inhibit unnecessary side reactions.

[0060] Optimize deformation energy to ensure that the metal clusters undergo only moderate structural adjustments during loading, neither causing excessive deformation nor aggregation or deactivation. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0062] Figure 1 To simulate implementation case 1, a series of model diagrams of γ-alumina loaded with single metal palladium and gold were constructed.

[0063] Figure 2 A series of γ-alumina-loaded bimetallic palladium-gold model diagrams were constructed to simulate implementation case 2.

[0064] Figure 3 This is the XRD pattern of the prepared γ-alumina-supported bimetallic palladium-gold catalyst.

[0065] Figure 4 This is the HRTEM image of the prepared γ-alumina-supported bimetallic palladium-gold catalyst.

[0066] Figure 5 This is the XPS graph of the prepared γ-alumina-supported bimetallic palladium-gold catalyst. DETAILED DESCRIPTION

[0067] The following detailed description of the embodiments of the present application is provided in conjunction with the accompanying drawings and examples. The detailed description of the following examples and the accompanying drawings are intended to illustrate the principles of the present application, but are not intended to limit the scope of the present application. The present application may be implemented in many different forms and is not limited to the specific embodiments disclosed herein, but rather includes all technical solutions within the scope of the claims.

[0068] The numbers mentioned in this application are by mass. The 3 and 1 in Pd3Au1d / γ-Al2O3(110) represent the number of atoms, and the same applies to the others. The "*" symbol in Example 3 represents the active site.

[0069] Example 1

[0070] A method for constructing a metal oxide-supported metal catalyst: the metal includes single metal palladium, single metal gold, and double metal palladium-gold.

[0071] The (110) crystal plane that occupies 83% of the exposed surface of the metal oxide γ-aluminum oxide (γ-Al2O3) was selected as the carrier to construct 10 to 13 layers of γ-Al2O3(110), the vacuum layer is The preferred size is There are 12 layers, including vacuum layer.

[0072] The γ-Al2O3 (110) crystal plane is selected as the carrier because it occupies up to 83% of the surface exposed area, which can provide abundant active sites and greatly enhance the effective surface area of the catalytic reaction. The γ-Al2O3(110) model is set The vacuum layer can effectively avoid the influence of periodic boundary conditions on the simulation results, ensuring the accuracy and reliability of the calculation. The preferred 12-layer γ-Al2O3(110) structure is The vacuum layer design not only optimizes the utilization of computing resources but also ensures sufficient model depth to reflect the behavior of real materials. This carefully designed support model provides an ideal platform for the subsequent loading of palladium-gold bimetallic clusters, allowing researchers to deeply explore key factors such as metal-support interactions, cluster dispersion, and stability at the atomic scale, thereby guiding the experimental synthesis of efficient and stable catalysts. This method not only improves the accuracy of theoretical predictions but also provides a solid foundation for experimental verification, helping to accelerate the transformation of new materials from laboratory to industrial application.

[0073] The coordination of Al atoms on the γ-Al2O3(110) plane includes threefold, fourfold, and sixfold coordination (Al3, Al4, and Al6), and the coordination of O atoms includes twofold and threefold coordination (O2 and O3). For the model of single-metal Pd supported on γ-Al2O3(110), Pd1 / γ-Al2O3(110), Pd2 / γ-Al2O3(110), Pd3 / γ-Al2O3(110), and Pd4 / γ-Al2O3(110) were investigated. For the model of single-metal Au supported on γ-Al2O3(110), Au1 / γ-Al2O3, Au2 / γ-Al2O3, Au3 / γ-Al2O3, and Au4 / γ-Al2O3 were investigated.

[0074] See also Figure 1 , is a series of γ-alumina loaded single metal palladium and gold model diagrams constructed in Example 1.

[0075] See also Figure 2 , a series of γ-type alumina loaded bimetallic palladium-gold model diagrams constructed in Example 1.

[0076] For the model of γ-Al2O3(110) loaded with bimetallic Pd-Au, Pd3Au1 / γ-Al2O3, Pd2Au2 / γ-Al2O3(110) and Pd1Au3 / γ-Al2O3(110) were investigated. According to the connection mode of Pd3Au1, Pd2Au2 and Pd1Au3 with γ-Al2O3(110), four configurations of Pd3Au1 / γ-Al2O3 catalyst were studied, which were named Pd3Au1a / γ-Al2O3(110), Pd3Au1b / γ-Al2O3(110), Pd3Au1c / γ-Al2O3(110) and Pd3Au1d / γ-Al2O3(110). For the Pd2Au2 / γ-Al2O3(110) catalyst, six configurations were studied, named Pd2Au2a / γ-Al2O3(110), Pd2Au2b / γ-Al2O3(110), Pd2Au2c / γ-Al2O3(110), Pd2Au2d / γ-Al2O3(110), Pd2Au2e / γ-Al2O3(110) and Pd2Au2f / γ-Al2O3(110). For the Pd1Au3 / γ-Al2O3(110) catalyst, four configurations were studied, named Pd1Au3a / γ-Al2O3(110), Pd1Au3b / γ-Al2O3(110), Pd1Au3c / γ-Al2O3(110) and Pd1Au3d / γ-Al2O3(110).

[0077] Based on stability considerations, five catalyst configurations were finally screened out: Pd4 / γ-Al2O3(110), Au4 / γ-Al2O3(110), Pd3Au1a / γ-Al2O3(110), Pd2Au2e / γ-Al2O3(110) and Pd1Au3b / γ-Al2O3(110).

[0078] Example 2

[0079] A method for constructing a metal oxide-supported metal catalyst configuration comprises the following steps:

[0080] Step S1: constructing the carrier γ-type aluminum oxide crystal surface

[0081] The γ-Al2O3(110) crystal plane model was constructed in MaterialsStudio software developed by Accelrys Corporation of the United States, with a 12-layer thickness and a vacuum layer added. To avoid the influence of periodic boundary conditions;

[0082] The exposed surface of γ-alumina (γ-Al2O3) is 83%, and the size of each layer is

[0083] Step S2: Constructing a single metal palladium cluster

[0084] Pd clusters with different atomic numbers were designed, including Pd1, Pd2, Pd3 and Pd4. The clusters Pd1, Pd2, Pd3 and Pd4 were placed on the surface of the carrier γ-Al2O3(110), and a stable catalyst configuration was found through optimization. After optimization, the catalyst configuration obtained was Pd4 / γ-Al2O3(110);

[0085] Step S3: Constructing a single metal gold cluster

[0086] Au clusters with different numbers of atoms were designed, including Au1, Au2, Au3 and Au4. Clusters Au1, Au2, Au3 and Au4 were placed on the surface of the carrier γ-Al2O3(110), and a stable catalyst configuration was found through optimization. After optimization, the catalyst configuration obtained was Au4 / γ-Al2O3(110);

[0087] Step S4: Constructing a bimetallic palladium-gold cluster

[0088] Pd-Au clusters with different atomic numbers and configurations were designed, including Pd3Au1, Pd2Au2, and Pd1Au3. The clusters Pd3Au1, Pd2Au2, and Pd1Au3 were placed on the surface of the carrier γ-Al2O3(110), and stable catalyst configurations were found through optimization. After optimization, the configurations obtained were Pd3Au1a / γ-Al2O3(110), Pd2Au2e / γ-Al2O3(110), and Pd1Au3b / γ-Al2O3(110).

[0089] Step S5: Configuration evaluation

[0090] The binding energy, adsorption energy and / or bond energy of each configuration in steps S2, S3 and S4 were calculated, and the interaction strength between the support γ-Al2O3(110) and monometallic Pd, monometallic Au and bimetallic Pd-Au was investigated to evaluate the stability and catalytic performance of each catalyst configuration.

[0091] In step S5, the evaluation index includes the binding energy E of the metal clusters bind (M n ) to evaluate the stability of metal clusters. The stability of metal clusters increases with E bind (M n ) increases and increases;

[0092] Formula (1) is: Ebind (M n )=[n×E(M)-E(M n )] / n, in formula (1), E(M n ) is the energy of the metal cluster, E(M) is the energy of a single metal, and n is the number of metal atoms.

[0093] In step S5, the evaluation index includes the bond energy E between the metal cluster and the carrier. bind (M n / S) to evaluate the stability of the supported catalyst. The stability of the supported catalyst increases with the increase of E bind (M n / S) increases with the increase;

[0094] Formula (2) is: E bind (M n / S)=[n×E(M n )+E(S)-E(M n / S)] / n, in formula (2), E(M n / S) is the energy of metal clusters loaded on the carrier, E(M n ) is the energy of the metal cluster, E(S) is the energy of the carrier, and n is the number of metal atoms.

[0095] In step S5, the evaluation index includes the adsorption energy E of the metal cluster loaded on the carrier ads (M n / S) to evaluate the interaction strength between metal clusters and supports and its effect on the stability of supported catalysts;

[0096] Formula (3a) is:

[0097] E ads (M n / S)=E(M n )+E(S)-E(M n / S), in formula (3a), E(M n / S) is the energy of metal clusters loaded on the carrier, E(M n ) is the energy of the metal cluster, and E(S) is the energy of the carrier;

[0098] Or, formula (3b) is:

[0099] E ads (M n / S)=E def (M n )+E def (S)+E int , where E def (M n ) is the deformation energy of the metal cluster, Edef (S) is the deformation energy of the carrier, E int is the interaction energy between metal clusters and supports.

[0100] In formula (3b), the adsorption energy E of metal clusters loaded on the carrier is ads (M n / S) can be decomposed into deformation energy, which includes the deformation energy E of the metal cluster. def (M n ) and the deformation energy E of the carrier def (S);

[0101] Formula (4) is:

[0102] E def (M n )=E(M n )-E(M' n ), where E(M n ) is the energy of the metal cluster, E(M n ′) is the energy of the adsorbed cluster;

[0103] Formula (5) is:

[0104] E def (S)=E(S)-E(S'), where E(S) is the energy of the carrier and E(S') is the energy of the carrier in the adsorbed state.

[0105] In formula (3b), the adsorption energy E of metal clusters loaded on the carrier is ads (M n / S) can be decomposed into the interaction energy E between the metal clusters and the support int ;

[0106] Formula (6) is:

[0107] E int =E(M' n )+E(S')-E(M n / S), where E(M n ′) is the energy of the adsorbed cluster, E(S′) is the energy of the adsorbed carrier, E(M n / S) is the energy of metal clusters loaded on the carrier.

[0108] According to the above formula, the screening results are shown in the table below

[0109] Table 1 Bond energy of isolated metal clusters (E bind (M n ), kJ·mol -1 ), the bond energy of metal loaded on the carrier

[0110] (E bind(M n / S), kJ·mol -1 ), adsorption energy (E ads (M n ), kJ·mol -1 ), the dissociation energy of the metal (E def (M n ), kJ·mol -1 ), the dissociation energy of the carrier (E def (S), kJ·mol -1 ), the interaction energy between metal and support (E int (M n / S), kJ·mol -1 ) and the metal bond length

[0111]

[0112] For γ-Al2O3(110) loaded with single metal Pd n For the (n=1-4) catalyst, the interaction between Pd4 composed of four Pd atoms and γ-Al2O3(110) is the largest, with the bond energy and adsorption energy being 296.7 and 340.6 kJ·mol -1 .

[0113] For γ-Al2O3(110) loaded with single metal Au n (n=1-4) catalysts, Au4 composed of four Au atoms has the largest interaction with γ-Al2O3(110), with bond energy and adsorption energy of 202.0 and 218.5 kJ·mol -1 .

[0114] For the bimetallic Pd3Au1 catalysts (Pd3Au1a, Pd3Au1b, Pd3Au1c, and Pd3Au1d) loaded on γ-Al2O3(110), the Pd3Au1a configuration has the largest interaction with the γ-Al2O3(110) support, with bond energy and adsorption energy of 286.6 and 353.8 kJ·mol -1 .

[0115] For γ-Al2O3(110) loaded bimetallic Pd2Au2 catalysts with different configurations (Pd2Au2a, Pd2Au2b, Pd2Au2c, Pd2Au2d, Pd2Au2e and Pd2Au2f), the Pd2Au2e configuration has the largest interaction with the support γ-Al2O3(110), with bond energy and adsorption energy of 268.5 and 361.7 kJ·mol -1 .

[0116] For γ-Al2O3(110) loaded bimetallic Pd1Au3 catalysts with different configurations (Pd1Au3a, Pd1Au3b, Pd1Au3c, and Pd1Au3d), the Pd3Au1a configuration has the largest interaction with the support γ-Al2O3(110), with bond energy and adsorption energy of 243.2 and 360.4 kJ·mol -1 .

[0117] In addition, from the structural diagrams of Pd4 / γ-Al2O3(110), Au4 / γ-Al2O3(110), Pd3Au1a / γ-Al2O3(110), Pd2Au2e / γ-Al2O3(110) and Pd1Au3b / γ-Al2O3(110) catalysts, it can be seen that when Pd atoms are directly connected to the support γ-Al2O3(110), they have a stronger interaction, which is attributed to the Pd with the same particle size. n and Au n (n = 1, 2, 3 and 4), Pd n The interaction with γ-Al2O3(110) is stronger than that with Au n Interaction with γ-Al2O3(110).

[0118] At the same particle size (e.g., a cluster of four atoms), the interaction strength between the Pd cluster and the γ-Al2O3(110) surface is greater than that between the Au cluster and the surface. This indicates that the bond energy and adsorption energy between the Pd and the support are higher, meaning that Pd is more easily and firmly attached to the γ-Al2O3(110) surface. The higher the bond energy and adsorption energy, the easier and more firmly Pd is attached to the γ-Al2O3(110) surface, and the more stable it is.

[0119] Even in bimetallic systems containing Au (such as Pd3Au1a / γ-Al2O3(110), Pd2Au2e / γ-Al2O3(110), and Pd3Au1b / γ-Al2O3(110)), as long as the Pd atoms can directly contact the support, they can form strong interactions, which contributes to the stability and activity of the overall catalyst.

[0120] Based on the above analysis, the clusters with the largest bond energy and adsorption energy, Pd4 / γ-Al2O3(110), Au4 / γ-Al2O3(110), Pd3Au1a / γ-Al2O3(110), Pd2Au2e / γ-Al2O3(110) and Pd1Au3b / γ-Al2O3(110) catalysts were further studied to study their effects on the one-step oxidative esterification of methacrolein.

[0121] Through the above screening process, we selected monometallic and bimetallic catalyst models with the largest bond energy and adsorption energy, which theoretically have the strongest interactions and thus exhibit the best catalytic performance.

[0122] Example 3

[0123] Based on the conclusions drawn from Example 2, theoretical calculations were used to study the formation of MMA along the path MAL+(CH3O)→CH2C(CH3)CO+(H)+CH3O→MMA+(H) on Pd4 / γ-Al2O3(110), Au4 / γ-Al2O3(110), Pd3Au1a / γ-Al2O3(110), Pd2Au2e / γ-Al2O3(110) and Pd1Au3b / γ-Al2O3(110) catalysts to clarify the effect of bimetallic components on the catalytic activity. Compared with the monometallic Pd4 / γ-Al2O3(110) and Au4 / γ-Al2O3(110) catalysts, the bimetallic Pd2Au2e / γ-Al2O3(110) and Pd1Au3b / γ-Al2O3(110) catalysts greatly promoted the first-step MAL dehydrogenation reaction (91.4 and 72.8 vs. 148.9 and 108.4 kJ·mol -1 ), while the Pd3Au1a / γ-Al2O3(110) catalyst inhibited the reaction (213.2 kJ·mol -1 For the second step coupling reaction of CH2CC(CH3)CO with CH3O, the interaction between Pd and Au in the Pd2Au2e / γ-Al2O3(110) catalyst greatly promoted the coupling of CH2CC(CH3)CO with CH3O (31.7 vs. 61.1 and 233.0 kJ·mol -1 ), the catalytic activity of Pd1Au3b / γ-Al2O3(110) catalyst is between that of single metal Pd4 / γ-Al2O3(110) and Au4 / γ-Al2O3(110) catalysts (105.6 kJ·mol -1 ), while Pd3Au1a / γ-Al2O3(110) and inhibited the reaction (268.6 kJ·mol -1 ).

[0124] Pd2Au2e / γ-Al2O3(110) exhibited excellent performance in both steps, especially in reducing the overall energy barrier. The synergistic effect of Pd and Au significantly promoted the dehydrogenation of MAL and the subsequent coupling reaction. The monometallic Pd catalyst Pd4 / γ-Al2O3(110) was more effective in the first step of dehydrogenation, but the overall energy barrier was still higher than that of the bimetallic catalyst. Au4 / γ-Al2O3(110) performed well in the first step of dehydrogenation, but had poor activity in the second step of coupling, resulting in the highest overall energy barrier. Therefore, based on the conclusions of theoretical calculations, experimental verification was carried out.

[0125] Example 4

[0126] The preparation process of supported catalyst Pd4 / γ-Al2O3 is as follows:

[0127] (1) Pretreatment of carrier γ-Al2O3:

[0128] Place a certain amount of carrier γ-Al2O3 in a watch glass and dry it in an oven at 110°C for 6-12 hours. Weigh an appropriate excess of γ-Al2O3 before drying, as there will be some loss when removing it from the watch glass.

[0129] (2) Loading of active components:

[0130] Weigh 3g of γ-Al2O3 into a 500ml three-necked flask and add 100ml of water. Ultrasonicate the mixture for 30 minutes, then add 100ml of a solution containing 0.252g of PdCl2 (the PdCl2 solution has been ultrasonically dispersed for 3 hours) and 8.462g of urea (Pd / Urea = 1 / 100). Heat in a water bath for 8 hours with vigorous mechanical stirring.

[0131] (3) Drying:

[0132] After heating is stopped, the mixture is washed with deionized water several times. Once sedimentation is complete, the mixture is transferred to a centrifuge tube and centrifuged at 3000 rpm for 15 minutes. After centrifugation, the supernatant is poured off, washed with 100 mL of deionized water, and centrifuged again. This step is repeated until no precipitation results from the addition of a 0.5 mol / L AgNO3 solution to the supernatant. The sample is then air-dried at 80°C for 12 hours.

[0133] (4) Reduction of micro-reactor:

[0134] The dried catalyst was placed in a mold and pressed into a sheet at 6 MPa pressure on a tablet press for 3 minutes. The catalyst particles were then ground and screened to a size of 20 to 40 mesh and placed in a quartz tube about 4 to 5 cm high. The quartz tube was then placed in a microreactor and passed through with high-purity hydrogen at a flow rate of 120 ml / min for 30 minutes to remove the air from the tube. A temperature program was then started with a controlled heating rate of 5°C / min. After reaching the designated temperature of 300°C, a timed reduction for 2 hours was started, with the hydrogen flow rate also controlled at 120 mL / min. Finally, the catalyst was cooled to room temperature under the protection of the same hydrogen flow rate, removed, and ground to less than 40 mesh to obtain the finished catalyst. The catalyst was then sealed and placed in a desiccator to protect from light. The product was Pd4 / γ-Al2O3.

[0135] The product is Pd4 / γ-Al2O3, which is used in the one-step oxidative esterification of methacrolein (MAL) and methanol (CH3OH) to prepare methyl methacrylate (MMA). The MAL conversion rate and MMA selectivity over the Pd4 / γ-Al2O3 catalyst are not high, only 56.9% and 47.6%, respectively. This indicates that the Pd catalyst is not efficient in promoting the conversion of MAL to MMA, and there should be a large number of side reactions or incomplete conversion.

[0136] Example 5

[0137] The preparation process of supported catalyst Au4 / γ-Al2O3 is as follows:

[0138] The preparation process of this embodiment is the same as that of embodiment 4, except that the loading of the active component in step (2) is as follows:

[0139] Weigh 3.000g of γ-Al2O3 into a 500ml three-necked flask, add 100ml of deionized water, and sonicate for 30 minutes. Once the support is dispersed, add 0.063g of HAuCl4 and 0.842g of urea, followed by 206ml of deionized water. The flask is then placed in an 80°C water bath with vigorous mechanical stirring and reflux.

[0140] The product is Au4 / γ-Al2O3, which is used in the one-step oxidative esterification of methacrolein (MAL) and methanol (CH3OH) to prepare methyl methacrylate (MMA).

[0141] The Au4 / γ-Al2O3 catalyst converts almost all of the MAL into products (with a conversion rate of 99.9%), but approximately 91.8% of this is the target product, MMA. Although the Au catalyst performs well in terms of conversion, a small amount of byproducts are still generated, resulting in a slightly lower selectivity for MMA than the ideal value. Since pure Pd and pure Au catalysts each have their own advantages and disadvantages in catalytic performance—Pd catalysts perform poorly in terms of selectivity, while Au catalysts, despite having a high conversion rate, still have certain selectivity issues—it is necessary to optimize the application of these two metals through adjustments in order to achieve higher MAL conversion rates and MMA selectivity.

[0142] Example 6

[0143] The preparation process of supported catalyst Pd2Au2 / γ-Al2O3(110) is as follows:

[0144] The preparation process of this embodiment is the same as that of embodiment 4, except that the loading of the active component in step (2) is as follows:

[0145] 3.000g of γ-Al2O3 was weighed and added to a 500ml three-necked flask. 100ml of deionized water was added and ultrasonicated for 30 minutes. After the support was dispersed, 0.063g of HAuCl4 and 0.842g of urea were added. 12.5ml of a 14.2mmol / L PdCl2 solution (0.252g of PdCl2 dissolved in 100ml of water) was added, and 193.5 parts of water was added. The apparatus was then placed in an 80°C water bath with vigorous mechanical stirring and reflux.

[0146] The product, Pd2Au2 / γ-Al2O3, is used in the one-step oxidative esterification of methacrolein (MAL) with methanol (CH3OH) to produce methyl methacrylate (MMA). The Pd2Au2e / γ-Al2O3 catalyst achieves a MAL conversion of up to 99.9% and an MMA selectivity of 99.7%.

[0147] Example 7

[0148] The Pd4 / γ-Al2O3, Au4 / γ-Al2O3 and Pd2Au2e / γ-Al2O3 catalysts prepared in Examples 4-6 were analyzed by XRD. Figure 3 It was found that all three catalysts showed obvious diffraction peaks of γ-Al2O3 (at 46.05° and 66.52°). The results showed that γ-Al2O3 phase existed in all samples, the difference being that the metals loaded on the three were different.

[0149] No diffraction peaks of Au were found in the two catalysts Au4 / γ-Al2O3 and Pd2Au2 / γ-Al2O3. Spectral peaks appeared at 38.2°, 44.4°, 64.6° and 77.7° (JCPDS65-8601), corresponding to the (111), (200), (220) and (311) crystal planes of Au. No obvious diffraction peak of Au(200) was found at 44°. The peak at 37° was not well judged due to the coverage of the γ-Al2O3 diffraction peak, which proved that the Au particles in the sample were small and scattered instead of forming a clear diffraction pattern, so they were not detected. Similarly, Pd4 / γ-Al2O3 had a characteristic peak corresponding to Pd(111) at 40.5°, indicating that Pd was also dispersed on the surface of the γ-Al2O3 carrier with a high degree of dispersion. This shows that the Pd4 cluster has a high stability, that is, E bind (pd4) is larger. For Au4 / γ-Al2O3 and Pd2Au2e / γ-Al2O3, no obvious diffraction peak of Au was observed, indicating that the Au particles are very small, even at the sub-nanometer scale. This highly dispersed state also reflects the E bind (Pd4) is larger because the Au clusters form a stable low-dimensional structure on the support.

[0150] All catalysts showed obvious γ-Al2O3 diffraction peaks, indicating that the support maintained a good crystal structure. For Pd4 / γ-Al2O3, the presence of the Pd (111) characteristic peak indicates that the interaction between Pd particles and γ-Al2O3 is strong, resulting in E bind (pd4 / S) is large. For Au4 / γ-Al2O3 and Pd2Au2e / γ-Al2O3, although no diffraction peak of Au was observed, the high dispersion of Au particles indicates that there is a strong interaction between it and the carrier, that is, E bind (Au4 / S), this strong interaction is due to the extremely small size of Au particles, which causes changes in their electronic structure and thus enhances the chemical bonding with the support.

[0151] The Pd(111) characteristic peak of Pd4 / γ-Al2O3 indicates that there is a strong interaction between Pd particles and γ-Al2O3, which is int Affects catalytic performance.

[0152] For Au4 / γ-Al2O3 and Pd2Au2e / γ-Al2O3, due to the high dispersion of Au particles, their E ads (Au4 / S) and E intThe excellent performance of Pd2Au2e / γ-Al2O3 (99.9% MAL conversion and 99.7% MMA selectivity) is attributed to the bimetallic synergistic effect, that is, the interaction between Pd and Au (through E int ) optimized the reaction pathway and improved selectivity and activity.

[0153] The failure to detect diffraction peaks for certain metals, such as Au, suggests that these metals exist in the form of very fine particles, i.e., have a high dispersion. This high dispersion is crucial for improving catalytic activity because it increases the number of active sites, thereby improving catalytic efficiency.

[0154] XRD analysis can indirectly assess whether the catalyst design has successfully achieved the desired metal dispersion state. This provides an important basis for further optimizing catalyst performance, especially in exploring how to better control metal particle size and distribution.

[0155] See also Figure 4 , further HRTEM analysis of the Pd2Au2e / γ-Al2O3 catalyst showed that the carrier γ-Al2O3 uniformly loaded the metal, and the average size of the metal particles was only 3.42nm, confirming the conclusion of small particle size mentioned in the XRD analysis. The lattice constant of the metal in the Pd2Au2e / γ-Al2O3 catalyst is Between Pd(111) and Au(111) The results indicate that bimetallic Pd-Au is formed.

[0156] The metal particles in the Pd2Au2e / γ-Al2O3 catalyst are very small (3.42 nm), indicating that these clusters have high stability. bind (Pd2Au2) is large. This high stability helps maintain the activity of the catalyst during the reaction. HRTEM images show that the metal particles are uniformly loaded on the γ-Al2O3 support and the particle size is small, which indicates that there is a strong interaction between the metal particles and the support (i.e., E bind (Pd2Au2 / S). This strong interaction helps improve the stability of the catalyst.

[0157] Since the metal particles are very small and evenly distributed, it means that their E ads (Pd2Au2 / S) and E int This strong adsorption energy is one of the reasons why the Pd2Au2e / γ-Al2O3 catalyst exhibits high conversion and selectivity. The excellent performance of Pd2Au2e / γ-Al2O3 is attributed to the small size and uniform distribution of metal particles, resulting in Edef (Pd2Au2) and E def (S) are larger. This increase in deformation energy helps to optimize the geometric configuration of the catalytic site, thereby improving the catalytic performance. The synergistic effect between Pd and Au, E int The catalytic performance was significantly optimized, which not only increased the conversion rate of MAL, but also greatly improved the selectivity of MMA.

[0158] See also Figure 5 , XPS analysis was performed on Au4 / γ-Al2O3 and Pd2Au2e / γ-Al2O3 catalysts. The Au4 / γ-Al2O3 catalyst showed two peaks at 83.4ev and 87.2ev, which are the bond energies of metallic Au. An increase in the bond energy value was clearly seen in the Pd2Au2e / γ-Al2O3 catalyst, indicating that Au gained electrons and the Pd in the alloy lost electrons. XRD analysis can infer that the particle size of Au in the Au / γ-Al2O3 and Pd1Au2 / γ-Al2O3 catalysts is very small, making it difficult to form obvious diffraction peaks; in contrast, the dispersion of Pd on Pd / γ-Al2O3 is also high, but because the particles may be slightly larger or less aggregated, its characteristic diffraction peaks can be observed. The γ-Al2O3 phase exists in all samples, and the positions of the main diffraction peaks are consistent, indicating that γ-Al2O3 as a carrier material maintains its original crystal structure and does not affect its function as a supporting material.

[0159] In summary, an embodiment of the construction, application and preparation of a metal oxide-supported bimetallic palladium-gold catalyst is provided. The method is simple and can be used to efficiently synthesize a variety of metal oxide-supported bimetallic palladium and gold on a large scale.

[0160] So far, the various embodiments of the present application have been described in detail. To avoid obscuring the concept of the present application, some details well known in the art have not been described. Based on the above description, those skilled in the art can fully understand how to implement the technical solutions disclosed herein.

[0161] Although some specific embodiments of the present application have been described in detail through examples, those skilled in the art will understand that the above examples are for illustrative purposes only and are not intended to limit the scope of the present application. Those skilled in the art will understand that the above embodiments may be modified or some technical features may be replaced by equivalents without departing from the scope and spirit of the present application. In particular, as long as there are no structural conflicts, the various technical features mentioned in the various embodiments may be combined in any manner.

Claims

1. A metal oxide supported metal catalyst configuration, characterized in that: The configurations include: Pd4 / γ-Al2O3(110), Au4 / γ-Al2O3(110), Pd3Au1a / γ-Al2O3(110), Pd2Au2e / γ-Al2O3(110) and Pd1Au3b / γ-Al2O3(110).

2. A method for constructing a metal oxide supported metal catalyst configuration, characterized in that: The following steps are involved: Step S1: constructing the carrier γ-type aluminum oxide crystal surface A γ-Al2O3(110) crystal plane model was constructed in molecular simulation software, multilayer thickness was set, and a vacuum layer was added to avoid the influence of periodic boundary conditions. Step S2: Constructing a single metal palladium cluster Pd clusters with different atomic numbers were designed, including Pd1, Pd2, Pd3 and Pd4. The clusters Pd1, Pd2, Pd3 and Pd4 were placed on the surface of the carrier γ-Al2O3(110), and a stable catalyst configuration was found through optimization. After optimization, the catalyst configuration obtained was Pd4 / γ-Al2O3(110); Step S3: Constructing a single metal gold cluster Au clusters with different numbers of atoms were designed, including Au1, Au2, Au3 and Au4. Clusters Au1, Au2, Au3 and Au4 were placed on the surface of the carrier γ-Al2O3(110), and a stable catalyst configuration was found through optimization. After optimization, the catalyst configuration obtained was Au4 / γ-Al2O3(110); Step S4: Constructing a bimetallic palladium-gold cluster Pd-Au clusters with different atomic numbers and configurations were designed, including Pd3Au1, Pd2Au2, and Pd1Au3. The clusters Pd3Au1, Pd2Au2, and Pd1Au3 were placed on the surface of the carrier γ-Al2O3(110), and stable catalyst configurations were found through optimization. After optimization, the configurations obtained were Pd3Au1a / γ-Al2O3(110), Pd2Au2e / γ-Al2O3(110), and Pd1Au3b / γ-Al2O3(110). Step S5: Configuration evaluation The binding energy, adsorption energy and / or bond energy of each configuration in steps S2, S3 and S4 were calculated, and the interaction strength between the support γ-Al2O3(110) and monometallic Pd, monometallic Au and bimetallic Pd-Au was investigated to evaluate the stability and catalytic performance of each catalyst configuration.

3. The method for constructing a metal oxide supported metal catalyst configuration according to claim 2, characterized in that: In step S1, the exposed surface of γ-alumina (γ-Al2O3) is 83%, the number of layers is 10 to 13, and the size of each layer is The vacuum layer is Preferably, the number of layers is 12, and the size of each layer is The vacuum layer is 4. The method for constructing a metal oxide supported metal catalyst configuration according to claim 2, characterized in that: In step S5, the evaluation index includes the binding energy E of the metal clusters bind (M n ) to evaluate the stability of metal clusters. The stability of metal clusters increases with E bind (M n ) increases and increases; Formula (1) is: E bind (M n )=[n×E(M)-E(M n )] / n, in formula (1), E(M n ) is the energy of the metal cluster, E(M) is the energy of a single metal, and n is the number of metal atoms.

5. The method for constructing a metal oxide supported metal catalyst configuration according to claim 2, wherein in step S5, the evaluation index includes the bond energy E between the metal cluster and the support. bind (M n / S) to evaluate the stability of the supported catalyst. The stability of the supported catalyst increases with the increase of E bind (M n / S) increases with the increase; Formula (2) is: E bind (M n / S)=[n×E(M n )+E(S)-E(M n / S)] / n, in formula (2), E(M n / S) is the energy of metal clusters loaded on the carrier, E(M n ) is the energy of the metal cluster, E(S) is the energy of the carrier, and n is the number of metal atoms.

6. The method for constructing a metal oxide supported metal catalyst configuration according to claim 2, characterized in that: In step S5, the evaluation index includes the adsorption energy E of the metal cluster loaded on the carrier ads (M n / S) to evaluate the interaction strength between metal clusters and supports and its effect on the stability of supported catalysts; Formula (3a) is: E ads (M n / S)=E(M n )+E(S)-E(M n / S), in formula (3a), E(M n / S) is the energy of metal clusters loaded on the carrier, E(M n ) is the energy of the metal cluster, and E(S) is the energy of the carrier; or, Formula (3b) is: E ads (Mn / S)=E def (Mn)+E def (S)+E int , where E def (M n ) is the deformation energy of the metal cluster, E def (S) is the deformation energy of the carrier, E int is the interaction energy between metal clusters and supports.

7. The method for constructing a metal oxide supported metal catalyst configuration according to claim 6, characterized in that: In formula (3b), the adsorption energy E of metal clusters loaded on the carrier is ads (M n / S) can be decomposed into deformation energy, which includes the deformation energy E of the metal cluster. def (Mn) and the deformation energy E of the carrier def (S); Formula (4) is: E def (M n )=E(M n )-E(M' n ), where E(M n ) is the energy of the metal cluster, E(M n ′) is the energy of the adsorbed cluster; Formula (5) is: E def (S)=E(S)-E(S'), where E(S) is the energy of the carrier and E(S') is the energy of the carrier in the adsorbed state.

8. The method for constructing a metal oxide supported metal catalyst configuration according to claim 6, characterized in that: In formula (3b), the adsorption energy E of metal clusters loaded on the carrier is ads (M n / S) can be decomposed into the interaction energy E between the metal clusters and the support int ; Formula (6) is: E int =E(M' n )+E(S')-E(M n / S), where E(M n ′) is the energy of the adsorbed cluster, E(S′) is the energy of the adsorbed carrier, E(M n / S) is the energy of metal clusters loaded on the carrier.

9. Use of the structure according to claim 1, or the structure constructed by the construction method according to any one of claims 2 to 9, for preparing methyl methacrylate in a one-step oxidative esterification reaction of methacrolein with methanol.

10. A method for preparing a γ-alumina-supported bimetallic palladium-gold catalyst having a configuration of Pd2Au2e / γ-Al2O3, characterized in that: Step 1: Weigh 3-5 parts of γ-Al2O3 and add it to 100-105 parts of water, and perform ultrasonic treatment to disperse the carrier; Step 2: Add 0.063-0.065 parts of HAuCl4 and 0.842-0.845 parts of urea to the solution in step 1, and add 12.0-12.5 parts of a PdCl2 solution having a concentration of 14.2-14.5 mmol / L and 193.5-195 parts of water; Step 3: Heat the mixture in step 2 in a water bath for 8-10 hours while vigorously stirring. After stopping heating, wash with deionized water until the precipitate cannot be detected by 0.5 mol / L AgNO3. Then, dry at 80-90°C for 12-15 hours and perform a reduction reaction to obtain the product Pd2Au2e / γ-Al2O3.

Images