Cu-based catalyst with excellent thermal stability for selective hydrogenation and preparation method thereof

Abstract

The application provides a Cu-based catalyst with excellent thermal stability for selective hydrogenation and a preparation method thereof. The method uses a nucleation / crystallization isolation method to instantaneously nucleate six kinds of mixed metal salt and alkali solution, to prepare high-entropy composite metal hydroxide (H-LDHs) with uniform element distribution and similar metal ratio. Further, based on the structure topological characteristics of H-LDHs, high-entropy oxides (HEOs) with good crystal form are obtained, and a series of Cu-M x / HEOs catalysts with flexible and adjustable geometric structure and electronic structure of catalytic microzone are obtained. In the hydrogenation reaction, the Cu-M x / HEOs catalyst has excellent initial activity and long-period usability, improves the poor stability of the Cu-based catalyst, and widens the industrial application of the Cu-based catalyst. The catalyst can be applied to the selective hydrogenation reaction of various alkynes in the fields of petroleum chemical industry, fine chemical industry and the like, and has outstanding catalytic performance. The catalyst also has good cyclic usability, and is easy to recycle and reuse.

Description

Technical Field

[0001] This invention belongs to the fields of petrochemicals and fine chemicals, and specifically relates to a catalyst for selective hydrogenation of carbon-carbon triple bonds and its preparation method. Background Technology

[0002] Ethylene is a crucial substance in various industrial production processes, particularly in the polymer industry, where its output is a marker of a nation's petrochemical sophistication. Globally, annual production of ethylene and propylene exceeds 200 million tons. Ethylene production utilizes steam-mediated high-hydrogen cracking reactions in high-temperature furnaces. However, this process produces approximately 0.1-1% acetylene, which can easily poison and deactivate catalysts used in downstream ethylene polymerization, thus impacting polyethylene production. Industrially, this problem is addressed through product separation and purification, and catalytic hydrogenation of acetylene. The most widely used method is the selective hydrogenation of acetylene to ethylene using heterogeneous catalysis, achieving both ethylene purification and increased ethylene yield. Therefore, selective hydrogenation of acetylene in excess ethylene is an important industrial process. For efficient polyethylene production, the industrial requirement is generally that the ethane content in the product be below 5 ppm. Several different reaction pathways exist during acetylene hydrogenation. When the main product of selective hydrogenation of acetylene is ethylene, potential byproducts include ethane (a product of deep hydrogenation of ethylene) and "green oil" formed by the oligomerization of acetylene hydrogenation. As a type of hydrogenation reaction, the selective hydrogenation of acetylene is a typical structure-sensitive reaction, meaning that the catalytic performance of the catalyst is heavily dependent on the particle size and dispersion of the active component. Furthermore, from a thermodynamic perspective, the standard molar enthalpy change of the main reaction is -172 kJ / mol, classifying it as a strongly exothermic reaction. When the reactants acetylene and hydrogen molecules react at the active sites on the catalyst surface, a certain temperature rise occurs on the catalyst surface, leading to localized heat accumulation in the catalyst bed, which poses a significant challenge to catalyst stability. From an industrial perspective, this can potentially cause problems such as system runaway and pressure loss. Therefore, achieving long-cycle, high-yield ethylene production has always been a key focus and objective of acetylene hydrogenation research.

[0003] In recent years, global precious metal reserves have decreased, the supply gap has widened year by year, and prices have risen rapidly. Therefore, the equivalent substitution of precious metals is of great significance in petrochemical processes. Since only one electron is filled in the 4s orbital of Cu, it has certain hydrogenation activity and excellent olefin selectivity. Shi et al. used atomic layer deposition to prepare Cu single atoms and a series of Cu nanoparticles of different sizes and investigated the influence of Cu geometry on acetylene hydrogenation performance (ACS Catal. 2020, 10(5): 3495-3504). Fu et al. constructed Fe with different Cu / Fe ratios through topological transformation of layered hydroxides. y MgO x Modified Cu interface structure, Cu at the interfaceδ- The activation sites play a crucial role in the activation of acetylene and hydrogen molecules, enhancing catalyst activity (ACS Catal. 2021, 11, 17, 11117–11128). However, copper nanoparticles have low Taman temperatures, making them prone to aggregation and growth, leading to irreversible catalyst deactivation and severely impacting catalyst stability. This is particularly true in high-temperature endothermic and strongly exothermic reactions, where harsh reaction conditions pose a significant challenge to the stability of Cu-based catalysts. When classical metal-support strong interaction (SMSI) occurs on the surface of supported metal catalysts, support species migrate to the surface of metal nanoparticles, forming encapsulations and inhibiting their aggregation and growth. This provides a unique solution for improving catalyst lifetime and has been widely applied. However, the physicochemical properties of Cu itself make it extremely difficult for SMSI to form on Cu-based catalysts. This is because metallic Cu has a low work function, which hinders electron acceptance, and its activation and dissociation capabilities for hydrogen are weak, making it difficult to promote support reduction. Therefore, it is difficult to meet the necessary conditions for SMSI formation, and unlike traditional noble metals, strong metal-support interactions cannot be formed under mild conditions. Therefore, designing a suitable catalyst structure to improve the stability of Cu-based catalysts is both crucial and challenging.

[0004] In recent years, high-entropy oxides have attracted widespread attention due to their unique structure and variable chemical properties. Based on their multi-component tunability, multiple elements can be simultaneously introduced into high-entropy oxides to obtain catalyst precursors with diverse structural compositions. Lattice distortion effects and the electronic structure diversity of high-entropy components can enhance the activity of catalytic materials. Entropy-driven structural stability can improve the long-term usability of catalysts, and the unique hysteresis effect of high-entropy materials can slow down or hinder the aggregation of catalytically active metals, which is beneficial to improving the structural stability and material integrity of catalysts. Layered composite metal oxides (LDHs) are a class of two-dimensional layered materials similar to magnesia, with highly uniform metal dispersion within the layers, and can be converted into oxides at low temperatures, giving them unique advantages in the preparation of high-entropy oxide materials. Therefore, this invention aims to use high-entropy oxides as precursors to activate some of the metals, utilizing their multi-component and entropy-stable structural characteristics to construct catalysts with heat dissipation functions, enabling catalytically active metals to exhibit good long-term usability under harsh conditions. Summary of the Invention:

[0005] The purpose of this invention is to provide a Cu-based catalyst with excellent thermal stability for selective hydrogenation and its preparation method. This catalyst is mainly used in the selective hydrogenation process of carbon-carbon triple bonds.

[0006] The catalyst provided by this invention is denoted as Cu-M. x / HEOs, where Cu is the active component and M is any one of the reducible auxiliary metals Zn, Fe, Co, Cr, Ni, Ga, Ti, and Mn, preferably Co or Fe; HEOs represents a Cu-based high-entropy oxide support, with an elemental composition of Cu+M1-5, M 1-5 It can be any five of Zn, Mg, Co, Ga, Al, Fe, Mn, Ni, and Cr, with Zn, Co, Fe, Ga, and Al being preferred; x is the ratio of M to the active metal Cu, x = 1-5.

[0007] The Cu-M for selective hydrogenation provided by this invention x The preparation method of / HEOs catalyst, the specific steps are as follows:

[0008] A. M 2+ M 3+ Metal salts with M 2+ / M 3+ A mixed salt solution is prepared by dissolving M in deionized water at an ion molar ratio of 2-3:1. 2+ There are three types of metal salts, and a Cu salt is required. 3+ There are three metal salts, and the total amount of metal ions in the mixed salt solution is 0.12-0.36 mol·L⁻¹. -1 Cu ions account for 15-20% of the total molar amount of metal ions, while the other two M ions account for... 2+ The metal ion content is similar, accounting for 35-40% of the total molar amount of metal ions. The remaining three are M 3+ The metal ion content is similar, accounting for 40-50% of the total molar amount of metal ions;

[0009] M in mixed salt solution 2+ / M 3+ The optimal molar ratio of metal ions is 2-2.2:1;

[0010] The M mentioned 2+ The salt is any two of Cu(NO3)2·3H2O, Zn(NO3)2·6H2O, Mg(NO3)2·6H2O, Co(NO3)2·6H2O, and Ni(NO3)2·6H2O; the M 3+ The salt is any three of the following: Ga(NO3)3·3H2O, Al(NO3)3·9H2O, Fe(NO3)3·9H2O, Mn(NO3)4·4H2O, and Cr(NO3)3·9H2O.

[0011] Dissolve any two of NaOH, KOH, Na₂CO₃, or NaHCO₃ in deionized water to prepare a solution with a concentration of 0.12-0.36 mol·L⁻¹. -1 alkaline solutions;

[0012] B. Start the nucleation reactor, set the stator-rotor gap to 0.1-1 mm and the rotation speed to 1000-3000 rpm, and dispense the mixed salt solution and alkali solution from step A separately using a peristaltic pump at a rate of 10-30 mL / min. -1 The same volume of metal cations are transported to the reactor at the same rate to rapidly nucleate, and the total number of metal cations in the salt solution is controlled to be equal to the number of anions in the alkaline solution. The nucleated slurry is collected at the slurry outlet.

[0013] The nucleation reactor is described in patent ZL201210105567.6;

[0014] C. The nucleating slurry is transferred to a crystallization container and crystallized at 60-120℃ for 6-18h. After naturally cooling to room temperature, the crystallized product is centrifuged and washed with deionized water until neutral. It is then dried in a freeze dryer for 12-24h to obtain a hexa-layered composite metal hydroxide high-entropy hydrotalcite, denoted as HEHs.

[0015] The elemental content of the obtained HEHs was determined by ICP, and their entropy values ​​were calculated. The formula for calculating the entropy value is as follows: When S config If the value is greater than 1.5R, then the high-entropy hydrotalcite has been successfully synthesized.

[0016] D. The HEHs obtained in step C are heated at 5-10℃·min. -1 The heating rate was increased to 400-800℃ in air atmosphere and calcined for 3-6 hours to obtain hexa-membered high-entropy oxides (HEOs).

[0017] E. The HEHs obtained in step D are reduced to 400-800℃ in a 10-20 vol H2 / N2 atmosphere at a rate of 2-10℃ / min for 3-6 h to obtain Cu-M. x / HEOs catalyst; since different metals have different reduction potentials and their reduction degree is proportional to the reduction temperature and reduction time, the type and proportion of M in the reduction support can be selectively reduced by controlling the reduction temperature and reduction time; Cu-M with the desired interface structure can be prepared. x Catalysts, among which catalysts with Cu-Co interface structure have better application performance.

[0018] The key features of this preparation method are: utilizing a nucleation / crystallization isolation method, a mixed solution of six metal salts is instantaneously mixed with an alkaline solution to form nuclei; by controlling key parameters such as the stator-rotor gap and rotational speed of the nucleation reactor, the crystal nucleation environment is enhanced, resulting in the synthesis of composite metal hydroxides (LDHs) with controllable nascent particle size; the rapid shearing in the nucleation / crystallization isolation method enables rapid mixing of the six metal salt solutions, overcoming the limitations of K+ between different metals. spThe limitations of the structure ensured that the metallic elements were uniformly dispersed within the layers of the hydrotalcite. Structural analysis and entropy calculations of the synthesized LDHs revealed that their configurational entropy exceeded 1.5R, meeting the standards for high-entropy materials. Furthermore, utilizing the structural topological effects of LDHs, copper-based high-entropy oxides (HEOs) with spinel crystals and controllable size and specific surface area were successfully prepared at lower temperatures. These HEOs were then used as precursors to prepare Cu-M alloys under controlled reduction conditions. x / HEOs catalyst. This catalyst has the characteristic of adjustable ratio of host metal Cu to guest metal M in the interfacial structure. More importantly, this material has the entropy stability characteristic unique to high-entropy materials. The Cu-based catalyst prepared by this method exhibits excellent catalytic activity and long service life in strongly exothermic hydrogenation reactions.

[0019] Figure 1 The image shows the X-ray diffraction (XRD) pattern of the HEOs precursor catalyst prepared in Example 1. It can be seen from the image that the HEOs crystal structure is good and can be classified as a spinel structure.

[0020] Figure 2 The image shows an HR-TEM image of the catalyst prepared in Example 1. It can be seen from the image that the support has a good crystal structure and some metal has been reduced to particles.

[0021] Figure 3 The image shows the Cu 2p XPS spectrum of the catalyst prepared in Example 1, indicating that most of the Cu in the support was reduced to Cu. 0 / Cu + .

[0022] Figure 4 The experimental results for the catalyst prepared in Example 1 in the selective hydrogenation reaction of acetylene are shown in Figure A, which is the curve of acetylene conversion versus temperature, and Figure B is the curve of acetylene selectivity versus acetylene conversion. When the reaction temperature is 200°C, the acetylene conversion is close to 100%, and the corresponding ethylene selectivity is 96%.

[0023] Figure 5 The stability results of the catalyst prepared in Example 1 in the selective hydrogenation reaction of acetylene are shown in Figure A, which is the curve of acetylene conversion versus time, and Figure B is the curve of acetylene selectivity versus time. The catalyst showed no significant performance degradation after 500 hours of continuous operation. At an acetylene conversion close to 100%, the ethylene selectivity was 95% ± 1%.

[0024] The beneficial effects of this invention are:

[0025] This catalyst uses Cu-based spinel-type high-entropy oxides transformed from six-membered high-entropy LDHs as precursors. After heat treatment under reducing conditions, a series of catalysts with heat dissipation capabilities are obtained. Based on the diversity of high-entropy material composition and structure, Cu-M catalysts with flexibly tunable catalytic microdomain geometry and electronic structure can be constructed. x The catalyst has catalytic active sites, thereby enhancing its initial activity. More importantly, the hysteresis diffusion effect and entropy stability characteristics unique to high-entropy materials effectively control the migration and aggregation of catalytic active centers, endowing the catalyst with heat dissipation capabilities and achieving structural stability under harsh reaction conditions. This catalyst exhibits high acetylene conversion and ethylene selectivity in the selective hydrogenation of acetylene, and demonstrates excellent long-term usability.

[0026] This catalyst effectively improves the problem of migration and aggregation caused by the low Taman temperature of Cu-based catalysts, enhances the structural stability of Cu catalysts, and broadens the industrial application prospects of Cu-based catalysts. Attached image description:

[0027] Figure 1 The image shows the XRD pattern of the catalyst precursor prepared in Example 1.

[0028] Figure 2 HR-TEM image of the catalyst prepared in Example 1.

[0029] Figure 3 The image shows the Cu 2p XPS spectrum of the catalyst prepared in Example 1.

[0030] Figure 4 The experimental results of the catalyst prepared in Example 1 in the selective hydrogenation reaction of acetylene are shown in Figure A, which is the curve of acetylene conversion versus temperature, and Figure B is the curve of acetylene selectivity versus acetylene conversion.

[0031] Figure 5 The results show the stability of the catalyst prepared in Example 1 in the selective hydrogenation reaction of acetylene. A is the curve of acetylene conversion versus time, and B is the curve of acetylene selectivity versus time. Detailed implementation method:

[0032] Example 1

[0033] A. Weigh 1.64g Cu(NO3)2·3H2O, 2.36g Zn(NO3)2·6H2O, 2.05g Mg(NO3)2·6H2O, 1.62g Fe(NO3)3·9H2O, 1.02g Ga(NO3)3·3H2O, and 1.5g Al(NO3)3·9H2O, and dissolve the six metal salts in 100mL of deionized water to prepare a mixed salt solution; weigh 2.03g Na2CO3 and 1.84g NaOH and dissolve them in 100mL of deionized water to prepare an alkaline solution.

[0034] B. Start the nucleation reactor, set the stator-rotor gap to 0.2 mm and the rotation speed to 3000 rpm, and dispense the mixed salt solution and alkali solution from step A separately using a peristaltic pump at a rate of 20 mL / min. -1 The slurry is rapidly fed into the reactor at a certain rate to nucleate, and the nucleated slurry is collected at the slurry outlet.

[0035] C. The nucleation slurry was added to a three-necked flask and crystallized in a 60°C water bath for 12 hours. After naturally cooling to room temperature, the crystallized product was centrifuged and washed with deionized water until neutral. The product was freeze-dried for 12 hours to obtain the layered composite metal high-entropy hydroxide precursor CuZnMgFeGaAl-LDHs; the entropy value of the obtained precursor was 1.65R.

[0036] D. The CuZnMgFeGaAl-LDHs precursor obtained in step C is subjected to a temperature of 5℃·min. -1 The heating rate was increased to 600℃ and calcined for 4 hours in air atmosphere to obtain the corresponding composite metal high entropy oxide CuZnMgFeGaAl-HEOs;

[0037] E. Dispose of the CuZnMgFeGaAl-HEOs obtained in step D at 10 vol.% H2 / N2 atmosphere at 10 °C·min. -1 The temperature was increased to 600℃ for 4 hours to reduce Cu and Fe in the precursor, and Cu-Fe / HEOs catalyst with Cu-Fe as the interfacial active element was obtained, with a Cu / Fe ratio of 1:1.

[0038] The catalyst prepared above was used in an experiment on the selective hydrogenation of acetylene:

[0039] 200 mg of catalyst was weighed and thoroughly mixed with 1.8 g of quartz sand with a particle size of 40-70 mesh, then placed into a quartz reaction tube with a diameter of 10 mm. Before the reaction, the sample was activated at 150 °C in a 10 vol.% H2 / N2 mixed gas for 2 h, and then naturally cooled to room temperature. The catalytic performance was tested at 100-220 °C, and the gas composition of the reactant gas was 0.71% acetylene / 2.86% hydrogen / 70.72% ethylene / 25.71% nitrogen balance gas. The test pressure was 1 bar, and the space velocity was 3800 h⁻¹. -1 The composition and content of reactants and products were analyzed by gas chromatography, and the data processing method was normalization. To ensure testing accuracy, results were recorded after reaching the specified temperature and holding for 30 minutes. Three sets of tests were performed, and the average value was taken as the catalytic performance data at that temperature. The results are shown in [Figure number missing]. Figure 4 .

[0040] Once the catalyst performance stabilized during the above tests, a stability evaluation was conducted. With catalytic performance at 100% acetylene conversion and >95% ethylene selectivity, tests were performed every 100 hours for a total of 500 hours to assess long-term stability. The results are shown below. Figure 5 .

[0041] Example 2

[0042] A. Weigh 1.64g Cu(NO3)2·3H2O, 2.36g Zn(NO3)2·6H2O, 2.05g Mg(NO3)2·6H2O, 1.62g Fe(NO3)3·9H2O, 1.02g Ga(NO3)3·3H2O, and 1.5g Al(NO3)3·9H2O, and dissolve the six metal salts in 100mL of deionized water to prepare a mixed salt solution; weigh 2.03g Na2CO3 and 2.36g KOH and dissolve them in 100mL of deionized water to prepare an alkaline solution.

[0043] B. Start the laboratory-made nucleation reactor, setting the stator-rotor gap to 0.1 mm and the rotation speed to 1500 rpm. Dispense the mixed salt solution and alkali solution from step A separately using a peristaltic pump at a rate of 30 mL / min. -1 The slurry is rapidly fed into the reactor at a certain rate to nucleate, and the nucleated slurry is collected at the slurry outlet.

[0044] C. The nucleation slurry was added to a three-necked flask and crystallized in an 80°C water bath for 18 hours. After naturally cooling to room temperature, the crystallized product was centrifuged and washed with deionized water until neutral. The product was freeze-dried for 24 hours to obtain the layered composite metal high-entropy hydroxide precursor CuZnMgFeGaAl-LDHs; the entropy value of the obtained precursor was 1.55R.

[0045] D. The CuZnMgFeGaAl-LDHs precursor obtained in step C is subjected to a temperature of 5℃·min. -1 The heating rate was increased to 600℃ and calcined for 3 hours in air atmosphere to obtain the corresponding composite metal high entropy oxide CuZnMgFeGaAl-HEOs;

[0046] E. Dispose of the CuZnMgFeGaAl-HEOs obtained in step D at 10 vol.% H2 / N2 atmosphere at 10 °C·min. -1 The temperature was increased to 800℃ for 5 hours, and the reduction of Cu and Fe in the precursor was deepened, resulting in a catalyst Cu-Fe2 / HEOs with Cu-Fe as the interfacial active element, in which the Cu / Fe ratio was 1:2.

[0047] Example 3

[0048] A. Weigh 1.64g Cu(NO3)2·3H2O, 2.38g Co(NO3)2·6H2O, 2.05g Mg(NO3)2·6H2O, 1.62g Fe(NO3)3·9H2O, 1.02g Ga(NO3)3·3H2O, and 1.5g Al(NO3)3·9H2O, and dissolve the six metal salts in 100mL of deionized water to prepare a mixed salt solution; weigh 2.03g Na2CO3 and 1.84g NaOH and dissolve them in 100mL of deionized water to prepare an alkaline solution.

[0049] B. Start the laboratory-made nucleation reactor, setting the stator-rotor gap to 0.2 mm and the rotation speed to 3000 rpm. Dispense the mixed salt solution and alkali solution from step A separately using a peristaltic pump at a rate of 20 mL / min. -1 The slurry is rapidly fed into the reactor at a certain rate to nucleate, and the nucleated slurry is collected at the slurry outlet.

[0050] C. The nucleation slurry was added to a three-necked flask and crystallized in a 70°C water bath for 6 hours. After naturally cooling to room temperature, the crystallized product was centrifuged and washed with deionized water until neutral. The product was freeze-dried for 12 hours to obtain the layered composite metal high-entropy hydroxide precursor CuCoMgFeGaAl-LDHs; the entropy value of the obtained precursor was 1.70R.

[0051] D. The CuCoFeMgGaAl-LDHs precursor obtained in step C was subjected to a temperature of 5℃·min. -1 The heating rate was increased to 600℃ and calcined for 5 hours in air atmosphere to obtain the corresponding composite metal high entropy oxide CuZnMgCoGaAl-HEOs;

[0052] E. The CuZnMgCoGaAl-HEOs obtained in step D is subjected to an incubation of 10 vol.% H2 / N2 atmosphere at 10 °C·min. -1 The temperature was increased to 600℃ for 6 hours to reduce Cu and Co in the precursor, and Cu-Co / HEOs catalyst with Cu-Co as the interfacial active element was obtained, with a Cu / Co ratio of 1:1.

[0053] Example 4

[0054] A. Weigh 1.64g Cu(NO3)2·3H2O, 2.35g Ni(NO3)2·6H2O, 2.05g Mg(NO3)2·6H2O, 1.62g Fe(NO3)3·9H2O, 1.02g Ga(NO3)3·3H2O, and 1.5g Al(NO3)3·9H2O, and dissolve the six metal salts in 100mL of deionized water to prepare a mixed salt solution; weigh 2.03g Na2CO3 and 1.84g NaOH and dissolve them in 100mL of deionized water to prepare an alkaline solution.

[0055] B. Start the laboratory-made nucleation reactor, setting the stator-rotor gap to 0.2 mm and the rotation speed to 3000 rpm. Dispense the mixed salt solution and alkali solution from step A separately using a peristaltic pump at a rate of 20 mL / min. -1 The slurry is rapidly fed into the reactor at a certain rate to nucleate, and the nucleated slurry is collected at the slurry outlet.

[0056] C. The nucleation slurry was added to a three-necked flask and crystallized in a 70°C water bath for 6 hours. After naturally cooling to room temperature, the crystallized product was centrifuged and washed with deionized water until neutral. The product was freeze-dried for 12 hours to obtain the layered composite metal high-entropy hydroxide precursor CuMgNiFeGaAl-LDHs; the entropy value of the obtained precursor was 1.65R.

[0057] D. The CuMgNiFeGaAl-LDHs precursor obtained in step C is subjected to a temperature of 5℃·min. -1 The heating rate was increased to 600℃ and calcined for 4 hours in air atmosphere to obtain the corresponding composite metal high entropy oxide CuMgNiFeGaAl-HEOs;

[0058] E. The CuMgNiFeGaAl-HEOs obtained in step D are subjected to an atmosphere of 10 vol.% H2 / N2 at 10 °C·min. -1 The temperature was increased to 600℃ for 6 hours to reduce Cu and Ni in the precursor, and Cu-Ni / HEOs catalyst with Cu-Ni as the interfacial active element was obtained, where the Cu / Ni ratio was 1:1.

[0059] Example 5

[0060] A. Weigh 1.64g Cu(NO3)2·3H2O, 2.35g Ni(NO3)2·6H2O, 2.05g Mg(NO3)2·6H2O, 1.62g Fe(NO3)3·9H2O, 1.62g Cr(NO3)3·9H2O, and 1.5g Al(NO3)3·9H2O, and dissolve the six metal salts in 100mL of deionized water to prepare a mixed salt solution; weigh 2.03g Na2CO3 and 1.84g NaOH and dissolve them in 100mL of deionized water to prepare an alkaline solution.

[0061] B. Start the laboratory-made nucleation reactor, setting the stator-rotor gap to 0.2 mm and the rotation speed to 3000 rpm. Dispense the mixed salt solution and alkali solution from step A separately using a peristaltic pump at a rate of 20 mL / min. -1 The slurry is rapidly fed into the reactor at a certain rate to nucleate, and the nucleated slurry is collected at the slurry outlet.

[0062] C. The nucleation slurry was added to a three-necked flask and crystallized in a 70°C water bath for 6 hours. After naturally cooling to room temperature, the crystallized product was centrifuged and washed with deionized water until neutral. The product was freeze-dried for 12 hours to obtain the layered composite metal high-entropy hydroxide precursor CuMgNiFeCrAl-LDHs; the entropy value of the obtained precursor was 1.75R.

[0063] D. The CuMgNiFeCrAl-LDHs precursor obtained in step C is heated at 5℃·min -1 The heating rate was increased to 600℃ and calcined for 5 hours in air atmosphere to obtain the corresponding composite metal high entropy oxide CuMgNiFeCrAl-HEOs;

[0064] E. The CuMgNiFeCrAl-HEOs obtained in step D is subjected to an incubation of 10 vol.% H2 / N2 atmosphere at 10 °C·min. -1 The temperature was increased to 800℃ for 5 hours to reduce Cu and Ni in the precursor, and Cu-Ni / HEOs catalyst with Cu-Ni as the interfacial active element was obtained, with a Cu / Ni ratio of 1:1.

Claims

1. A method for preparing a Cu-based catalyst with excellent thermal stability for selective hydrogenation, characterized in that: The specific steps of this preparation method are as follows: A. Weigh 1.64 g Cu(NO3)2·3H2O, 2.36 g Zn(NO3)2·6H2O, 2.05 g Mg(NO3)2·6H2O, 1.62 g Fe(NO3)3·9H2O, 1.02 g Ga(NO3)3·3H2O, and 1.5 g Al(NO3)3·9H2O, and dissolve the six metal salts in 100 mL of deionized water to prepare a mixed salt solution; weigh 2.03 g Na2CO3 and 1.84 g NaOH and dissolve them in 100 mL of deionized water to prepare an alkaline solution. B. Start the nucleation reactor, set the stator-rotor gap to 0.2 mm and the rotation speed to 3000 rpm, and dispense the mixed salt solution and alkali solution from step A separately using a peristaltic pump at a rate of 20 mL / min. -1 The slurry is rapidly fed into the reactor at a certain rate to nucleate, and the nucleated slurry is collected at the slurry outlet. C. The nucleation slurry was added to a three-necked flask and crystallized in a water bath at 60 °C for 12 h. After naturally cooling to room temperature, the crystallized product was centrifuged and washed with deionized water until neutral. The product was freeze-dried for 12 h to obtain the layered composite metal high-entropy hydroxide precursor CuZnMgFeGaAl-LDHs. The entropy value of the obtained precursor was 1.65R. D. The CuZnMgFeGaAl-LDHs precursor obtained in step C was subjected to a temperature of 5 °C·min. -1 The heating rate was increased to 600 °C and calcined for 4 h in air atmosphere to obtain the corresponding composite metal high entropy oxide CuZnMgFeGaAl-HEOs; E. The CuZnMgFeGaAl-HEOs obtained in step D were subjected to a 10 vol.% H2 / N2 atmosphere at 10 °C·min. -1 The temperature was increased to 600 °C for 4 h to reduce Cu and Fe in the precursor, and Cu-Fe / HEOs catalyst with Cu-Fe as the interfacial active element was obtained, with a Cu / Fe ratio of 1:

1.

2. A method for preparing a Cu-based catalyst with excellent thermal stability for selective hydrogenation, characterized in that: The specific steps of this preparation method are as follows: A. Weigh 1.64 g Cu(NO3)2·3H2O, 2.36 g Zn(NO3)2·6H2O, 2.05 g Mg(NO3)2·6H2O, 1.62 g Fe(NO3)3·9H2O, 1.02 g Ga(NO3)3·3H2O, and 1.5 g Al(NO3)3·9H2O, and dissolve the six metal salts in 100 mL of deionized water to prepare a mixed salt solution; weigh 2.03 g Na2CO3 and 2.36 g KOH and dissolve them in 100 mL of deionized water to prepare an alkaline solution. B. Start the laboratory-made nucleation reactor, setting the stator-rotor gap to 0.1 mm and the rotation speed to 1500 rpm. Dispense the mixed salt solution and alkali solution from step A separately using a peristaltic pump at a rate of 30 mL / min. -1 The slurry is rapidly fed into the reactor at a certain rate to nucleate, and the nucleated slurry is collected at the slurry outlet. C. The nucleation slurry was added to a three-necked flask and crystallized in a water bath at 80 °C for 18 h. After naturally cooling to room temperature, the crystallized product was centrifuged and washed with deionized water until neutral. The product was freeze-dried for 24 h to obtain the layered composite metal high-entropy hydroxide precursor CuZnMgFeGaAl-LDHs. The entropy value of the obtained precursor was 1.55R. D. The CuZnMgFeGaAl-LDHs precursor obtained in step C was subjected to a temperature of 5 °C·min. -1 The heating rate was increased to 600 °C and calcined for 3 h in air atmosphere to obtain the corresponding composite metal high entropy oxide CuZnMgFeGaAl-HEOs; E. The CuZnMgFeGaAl-HEOs obtained in step D were subjected to a 10 vol.% H2 / N2 atmosphere at 10 °C·min. -1 The temperature was increased to 800 °C for 5 h to reduce Cu and Fe in the precursor, and the reduction of Cu and Fe in the precursor was increased to obtain Cu-Fe2 / HEOs catalyst with Cu-Fe as the interfacial active element, and the Cu / Fe ratio was 1:

2.

3. A method for preparing a Cu-based catalyst with excellent thermal stability for selective hydrogenation, characterized in that: The specific steps of this preparation method are as follows: A. Weigh 1.64 g Cu(NO3)2·3H2O, 2.38 g Co(NO3)2·6H2O, 2.05 g Mg(NO3)2·6H2O, 1.62 g Fe(NO3)3·9H2O, 1.02 g Ga(NO3)3·3H2O, and 1.5 g Al(NO3)3·9H2O, and dissolve the six metal salts in 100 mL of deionized water to prepare a mixed salt solution; weigh 2.03 g Na2CO3 and 1.84 g NaOH and dissolve them in 100 mL of deionized water to prepare an alkaline solution. B. Start the laboratory-made nucleation reactor, setting the stator-rotor gap to 0.2 mm and the rotation speed to 3000 rpm. Dispense the mixed salt solution and alkali solution from step A separately using a peristaltic pump at a rate of 20 mL / min. -1 The slurry is rapidly fed into the reactor at a certain rate to nucleate, and the nucleated slurry is collected at the slurry outlet. C. The nucleation slurry was added to a three-necked flask and crystallized in a water bath at 70 °C for 6 h. After naturally cooling to room temperature, the crystallized product was centrifuged and washed with deionized water until neutral. The product was freeze-dried for 12 h to obtain the layered composite metal high-entropy hydroxide precursor CuCoFeMgGaAl-LDHs. The entropy value of the obtained precursor was 1.70R. D. The CuCoFeMgGaAl-LDHs precursor obtained in step C was subjected to a temperature of 5 °C·min. -1 The heating rate was increased to 600 °C and calcined for 5 h in air atmosphere to obtain the corresponding composite metal high entropy oxide CuCoFeMgGaAl-HEOs; E. The CuCoFeMgGaAl-HEOs obtained in step D were subjected to a 10 vol.% H2 / N2 atmosphere at 10 °C·min. -1 The temperature was increased to 600 °C for 6 h to reduce Cu and Co in the precursor, and Cu-Co / HEOs catalyst with Cu-Co as the interfacial active element was obtained, with a Cu / Co ratio of 1:

1.

4. A method for preparing a Cu-based catalyst with excellent thermal stability for selective hydrogenation, characterized in that: The specific steps of this preparation method are as follows: A. Weigh 1.64 g Cu(NO3)2·3H2O, 2.35 g Ni(NO3)2·6H2O, 2.05 g Mg(NO3)2·6H2O, 1.62 g Fe(NO3)3·9H2O, 1.02 g Ga(NO3)3·3H2O, and 1.5 g Al(NO3)3·9H2O, and dissolve the six metal salts in 100 mL of deionized water to prepare a mixed salt solution; weigh 2.03 g Na2CO3 and 1.84 g NaOH and dissolve them in 100 mL of deionized water to prepare an alkaline solution. B. Start the laboratory-made nucleation reactor, setting the stator-rotor gap to 0.2 mm and the rotation speed to 3000 rpm. Dispense the mixed salt solution and alkali solution from step A separately using a peristaltic pump at a rate of 20 mL / min. -1 The slurry is rapidly fed into the reactor at a certain rate to nucleate, and the nucleated slurry is collected at the slurry outlet. C. The nucleation slurry was added to a three-necked flask and crystallized in a water bath at 70 °C for 6 h. After naturally cooling to room temperature, the crystallized product was centrifuged and washed with deionized water until neutral. The product was freeze-dried for 12 h to obtain the layered composite metal high-entropy hydroxide precursor CuMgNiFeGaAl-LDHs. The entropy value of the obtained precursor was 1.65R. D. The CuMgNiFeGaAl-LDHs precursor obtained in step C is subjected to a temperature of 5 °C·min. -1 The heating rate was increased to 600 °C and calcined for 4 h in air atmosphere to obtain the corresponding composite metal high entropy oxide CuMgNiFeGaAl-HEOs; E. The CuMgNiFeGaAl-HEOs obtained in step D were subjected to a 10 vol.% H2 / N2 atmosphere at 10 °C·min. -1 The temperature was increased to 600 °C for 6 h to reduce Cu and Ni in the precursor, and Cu-Ni / HEOs catalyst with Cu-Ni as the interfacial active element was obtained, with a Cu / Ni ratio of 1:1.

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