Hierarchical pore copper-based solid solution catalyst as well as preparation method and application thereof

Abstract

The invention discloses a hierarchical pore copper-based solid solution catalyst as well as a preparation method and application thereof, and belongs to the technical field of catalyst preparation and catalytic reaction engineering. The catalyst comprises the following components: CuO, CeO2, ZrO2, Al2O3 and SiO2, and is provided with multistage micropores and mesopores. In the preparation process, copper species, cerium species and zirconium species are utilized to form a solid solution, strong interaction is formed, and the stability of the catalyst is improved; the surface of the catalyst is rich in coordination sites of active copper centers and oxygen vacancies, hierarchical pore channels with staggered micropores and mesopores are distributed in the catalyst, copper species and other components form strong interaction, and the problems that an ethynylation catalyst is low in activity and poor in stability can be solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalyst preparation and catalytic reaction engineering, and specifically relates to a multi-level porous copper-based solid solution catalyst, a preparation method and an application thereof. Background Art

[0002] The synthesis of 1,4-butynediol from formaldehyde acetylation (Reppe process) as a source reaction combines the raw material advantages of coal-based primary chemicals with the huge market demand for downstream high-value-added chemicals, playing a key role in establishing an industrial chain for efficient and comprehensive coal utilization. Downstream high-value-added chemicals derived from 1,4-butynediol, such as 1,4-butanediol, tetrahydrofuran, γ-butyrolactone, and polybutylene succinate, are widely used in various sectors of national economy and people's livelihoods. Industrially, copper-based catalysts are the core technology for the formaldehyde acetylation to 1,4-butynediol. During the formaldehyde acetylation reaction, performance optimization of acetylation catalysts often focuses on enhancing their acetylene activation ability. The authorized invention patent (Wang Zhipeng, Song Wei, Song Jian, and Li Yu, ZL202211068331.X) introduces basic sites on the catalyst surface to activate acetylene molecules together with active copper centers, but their activation ability for the reactant formaldehyde is limited. Furthermore, the pore structure of acetylation catalysts is primarily mesoporous, which prevents them from effectively screening and restricting the adsorption and desorption of small reactants and larger product molecules. The limited activity and single pore structure of these catalysts leave room for further improvement in their acetylation activity. Furthermore, the weak interaction between the active copper species and the support also hinders catalyst stability. Therefore, effectively improving the catalytic activity and stability of copper-based catalysts is a common concern in both industry and academia. Summary of the Invention

[0003] The present invention overcomes the deficiencies of the prior art and proposes a multi-level porous copper-based solid solution catalyst, a preparation method, and an application thereof; and solves the technical problems of low intrinsic activity of copper-based acetylation catalysts, limited adsorption and diffusion of reactant and product molecules on the catalyst surface and pores, and easy reduction of active copper species, resulting in poor catalyst stability.

[0004] The present invention is achieved through the following technical solutions: A multi-level porous copper-based solid solution catalyst, wherein the catalyst surface is rich in synergistic sites of active copper centers and oxygen vacancies, and the interior is distributed with multi-level pores interlaced with micropores and mesopores; based on 100% by mass of the catalyst, the CuO content is 15-30 wt%, the CeO2 content is 10-30 wt%, the ZrO2 content is 5-20 wt%, the Al2O3 content is 2-10 wt%, and the SiO2 content is 10-30 wt%. The pore size distribution of the multi-level pores of the catalyst, i.e., the micropores and mesopores, is 0.5-1 nm and 25-50 nm, respectively; the specific surface area of the catalyst is 50-150 m 2 / g.

[0005] A method for preparing a multi-level porous copper-based solid solution catalyst comprises the following steps: S1. According to the catalyst composition ratio, copper salt, aluminum salt, silicon source, cerium salt, and zirconium salt are dissolved in water to prepare a mixed solution with a total metal ion concentration of 0.5 to 3.0 mol / L; urea in an amount of 1.2 to 1.6 times the metal ion equivalent is added thereto and mixed thoroughly to obtain a metal ion mixed solution; S2. heating the metal ion mixed solution at 85-95° C. with stirring to allow the metal ions to fully and evenly precipitate; when the metal ions are completely precipitated and the pH of the system remains unchanged, maintaining the temperature and stirring for 2-4 hours, and then allowing to stand at room temperature for 12-18 hours; S3, drying the precipitate obtained in step S2 and calcining it at 300-650° C. in an atmosphere for 2-6 h to obtain a solid oxide; S4. Reacting the obtained solid oxide in ethanol-water at 80-100° C. in a high-pressure reactor for 3-8 hours; the volume ratio of ethanol-water is preferably 1:2.

[0006] S5. Drying the reactant obtained in S4 to obtain a multi-level porous copper-based solid solution catalyst.

[0007] Preferably, the thorough mixing in step S1 is ultrasonic mixing for 15 to 25 minutes.

[0008] Preferably, in step S3, the drying is performed by filtering the precipitate obtained in step S2 3 to 6 times and drying it at 75 to 95°C.

[0009] Preferably, in step S5, the drying is to vacuum dry the reactant obtained in S4 at 75-95°C.

[0010] Preferably, the copper salt is one or any combination of copper nitrate, copper sulfate, and copper chloride; and the aluminum salt is one or any combination of aluminum nitrate, aluminum sulfate, and aluminum chloride.

[0011] Preferably, the silicon source is one or any combination of ethyl silicate, silica sol, and sodium silicate.

[0012] Preferably, the cerium salt is one or any combination of cerium nitrate, cerium sulfate, and cerium chloride; and the zirconium salt is one or any combination of zirconium nitrate, zirconium sulfate, and zirconium chloride.

[0013] Preferably, the atmosphere is one or any combination of nitrogen, argon and helium.

[0014] Application of the hierarchical porous copper-based solid solution catalyst or the hierarchical porous copper-based solid solution catalyst obtained by the preparation method in the synthesis of 1,4-butynediol by formaldehyde acetylation reaction.

[0015] The beneficial effects of the present invention compared to the prior art are: 1. The catalyst surface of the present invention has abundant copper active sites and oxygen vacancy sites, wherein the copper active sites activate acetylene molecules, and the oxygen vacancies activate the carbonyl groups of formaldehyde, which is conducive to the addition of acetylene and formaldehyde and accelerates the catalytic reaction rate. The catalyst utilizes copper species, cerium species, and zirconium species to form a solid solution, forming a strong interaction and improving the stability of the catalyst.

[0016] 2. The catalyst described in the present invention has a multi-level pore structure of micropores and mesopores. The micropores are conducive to the diffusion and adsorption of small-sized reactant molecules into the pores, while the mesopores are conducive to the desorption and diffusion of larger-sized product butynediol molecules out of the pores, thereby improving mass transfer during the reaction and achieving the effect of improving catalytic efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a TEM image of the hierarchically porous copper-based solid solution catalyst prepared in Example 2 of the present invention.

[0018] Figure 2 This is an SEM image of the hierarchical porous copper-based solid solution catalyst prepared in Example 2 of the present invention.

[0019] Figure 3 This is the XRD pattern of the hierarchical porous copper-based solid solution catalyst prepared in Example 2 of the present invention.

[0020] Figure 4 This is the Raman graph of the hierarchical porous copper-based solid solution catalyst prepared in Example 2 of the present invention.

[0021] Figure 5 This is the Raman graph of the hierarchical porous copper-based solid solution catalyst prepared in Example 3 of the present invention.

[0022] Figure 6 This is a full-pore physical adsorption-desorption curve of the multi-level porous copper-based solid solution catalyst prepared in Example 3 of the present invention. DETAILED DESCRIPTION

[0023] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail with reference to the embodiments and the accompanying drawings. It should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention. The technical solutions of the present invention will be described in detail below with reference to the embodiments and the accompanying drawings, but the scope of protection is not limited thereto.

[0024] Unless otherwise specified, the production processes, experimental methods or detection methods involved in the embodiments of the present invention are all conventional methods in the prior art, and their names and / or abbreviations are conventional names in the field and are very clear and unambiguous in the relevant fields of use. Those skilled in the art can understand the conventional process steps based on the names and apply the corresponding equipment to implement them according to conventional conditions or the conditions recommended by the manufacturer.

[0025] The various instruments, equipment, raw materials or reagents used in the embodiments of the present invention are not particularly limited in their sources and are all conventional products that can be purchased through regular commercial channels or prepared according to conventional methods well known to those skilled in the art. Example

[0026] A hierarchically porous copper-based solid solution catalyst, wherein the mass of the catalyst is 100%, the CuO content is 30 wt%, the Al2O3 content is 8 wt%, the SiO2 content is 20 wt%, the CeO2 content is 28 wt%, the ZrO2 content is 14 wt%, the pore size distribution of micropores and mesopores is 0.72 nm and 39 nm, respectively, and the specific surface area is 74 m 2 / g.

[0027] The preparation method of the multi-level porous copper-based solid solution catalyst comprises the following steps: Take 9.11 g Cu(NO3)2·3H2O, 5.89 g Al(NO3)3·9H2O, 7.14 g TEOS (SiO2 content 28%), 7.06 g Ce(NO3)3·6H2O and 4.88 g Zr(NO3)4·5H2O, dissolve them in water to prepare a mixed solution with a total metal ion concentration of 1.6 mol / L; add urea (1.6 times the metal ion equivalent) into it and ultrasonically mix for 20 min.

[0028] (2) The mixed solution prepared in step (1) was heated at 85 °C and stirred. As the reaction progressed, urea continuously released OH. -The ions make the pH of the reaction system increase continuously, and the metal ions form a uniform precipitation. When the metal ions are completely precipitated and the pH of the system remains unchanged, stir at 85 °C for 2 h and let it stand at room temperature for 12 h. (3) The precipitate was filtered five times, dried at 75 °C, and calcined at 300 °C for 2 h in a nitrogen atmosphere. (4) The solid oxide obtained by calcining in step (3) was reacted in ethanol-water (volume ratio 1:2) at 90°C in a high-pressure reactor for 3 h; (5) Dry the solid obtained in step (4) under vacuum at 75°C; grind the obtained solid oxide for later use. Example

[0029] A hierarchically porous copper-based solid solution catalyst, wherein, based on the mass of the catalyst being 100%, the CuO content is 25 wt%, the Al2O3 content is 10 wt%, the SiO2 content is 17 wt%, the CeO2 content is 28 wt%, the ZrO2 content is 20 wt%, the pore size distributions of the micropores and mesopores are 0.81 nm and 33 nm, respectively, and the specific surface area is 87 m 2 / g.

[0030] The preparation method of the multi-level porous copper-based solid solution catalyst comprises the following steps: (1) Dissolve 7.59 g Cu(NO3)2·3H2O, 7.36 g Al(NO3)3·9H2O, 6.07 g TEOS (SiO2 content 28%), 7.06 g Ce(NO3)3·6H2O, and 6.97 g Zr(NO3)4·5H2O in water to prepare a mixed solution with a total metal ion concentration of 1.9 mol / L. Add urea (1.4 times the metal ion equivalent) and mix by ultrasonication for 20 min.

[0031] (2) The mixed solution prepared in step (1) is heated at 95°C and stirred. As the reaction progresses, urea continuously releases OH - The ions make the pH of the reaction system increase continuously, and the metal ions form a uniform precipitation. When the metal ions are completely precipitated and the pH of the system remains unchanged, stir at 95 °C for 4 h and let it stand at room temperature for 18 h. (3) The precipitate was filtered five times, dried at 85 °C, and calcined at 650 °C for 2 h in an argon atmosphere. (4) the solid oxide obtained by calcining in step (3) was reacted in an autoclave at 90°C in ethanol-water (volume ratio 1:2) for 4 h; (5) Dry the solid obtained in step (4) under vacuum at 80°C; grind the obtained solid oxide for later use. Example

[0032] A hierarchically porous copper-based solid solution catalyst, wherein, based on the mass of the catalyst being 100%, the CuO content is 27 wt%, the Al2O3 content is 5 wt%, the SiO2 content is 30 wt%, the CeO2 content is 20 wt%, the ZrO2 content is 18 wt%, the pore size distributions of micropores and mesopores are 0.6 nm and 35 nm, respectively, and the specific surface area is 106 m 2 / g.

[0033] The preparation method of the multi-level porous copper-based solid solution catalyst comprises the following steps: (1) Take 5.79 g CuCl2·2H2O, 3.68 g Al(NO3)3·9H2O, 7.5 g silica sol (SiO2 content 40%), 5.05 g Ce(NO3)3·6H2O and 6.27 g Zr(NO3)4·5H2O, dissolve them in water to prepare a mixed solution with a total metal ion concentration of 2.4 mol / L; add urea (1.3 times the metal ion equivalent) into the solution and mix it by ultrasonic mixing for 20 min.

[0034] (2) The mixed solution prepared in step (1) was heated at 90 °C and stirred. As the reaction progressed, urea continuously released OH. - The ions make the pH of the reaction system increase continuously, and the metal ions form a uniform precipitation. When the metal ions are completely precipitated and the pH of the system remains unchanged, stir at a constant temperature of 90 ° C for 4 hours and let it stand at room temperature for 18 hours. (3) The above precipitate was filtered 3 to 6 times, dried at 75 °C, and calcined at 350 °C for 3 h in a helium atmosphere; (4) the solid oxide obtained by calcining in step (3) was reacted in an autoclave at 90°C in ethanol-water (volume ratio 1:2) for 6 h; (5) Dry the solid obtained in step (4) under vacuum at 85°C; grind the obtained solid oxide for later use. Example

[0035] A hierarchically porous copper-based solid solution catalyst, wherein, based on the mass of the catalyst being 100%, the CuO content is 20 wt%, the Al2O3 content is 10 wt%, the SiO2 content is 25 wt%, the CeO2 content is 25 wt%, the ZrO2 content is 20 wt%, the pore size distributions of the micropores and mesopores are 0.64 nm and 40 nm, respectively, and the specific surface area is 92 m 2 / g.

[0036] The preparation method of the multi-level porous copper-based solid solution catalyst comprises the following steps: (1) 4.29 g CuCl2·2H2O, 3.36 g Al2(SO4)3, 6.25 g silica sol (SiO2 content 40%), 5.41 g CeCl3·7H2O, and 6.97 g Zr(NO3)4·5H2O were dissolved in water to prepare a mixed solution with a total metal ion concentration of 2.1 mol / L. Urea (1.4 times the metal ion equivalent) was added to the solution and ultrasonically mixed for 20 min.

[0037] (2) The mixed solution prepared in step (1) was heated at 85 °C and stirred. As the reaction progressed, urea continuously released OH. - The ions make the pH of the reaction system increase continuously, and the metal ions form a uniform precipitation. When the metal ions are completely precipitated and the pH of the system remains unchanged, stir at a constant temperature of 85 ° C for 3 h and let it stand at room temperature for 15 h. (3) The precipitate was filtered 3 to 6 times, dried at 95 °C, and calcined at 450 °C for 4 h in an argon atmosphere; (4) the solid oxide obtained by calcining in step (3) was reacted in an autoclave at 90°C in ethanol-water (volume ratio 1:2) for 3 h; (5) Dry the solid obtained in step (4) under vacuum at 90°C; grind the obtained solid oxide for later use. Example

[0038] A hierarchically porous copper-based solid solution catalyst, wherein, based on the mass of the catalyst being 100%, the CuO content is 30 wt%, the Al2O3 content is 9 wt%, the SiO2 content is 20 wt%, the CeO2 content is 28 wt%, the ZrO2 content is 13 wt%, the pore size distributions of the micropores and mesopores are 0.69 nm and 39 nm, respectively, and the specific surface area is 88 m 2 / g.

[0039] The preparation method of the multi-level porous copper-based solid solution catalyst comprises the following steps: (1) Dissolve 9.42 g CuSO4·5H2O, 3.02 g Al2(SO4)3, 7.07 g Na2SiO3·5H2O, 6.06 g CeCl3·7H2O, and 2.46 g ZrCl4 in water to prepare a mixed solution with a total metal ion concentration of 1.8 mol / L. Add urea (1.6 times the metal ion equivalent) and mix ultrasonically for 20 min.

[0040] (2) The mixed solution prepared in step (1) was heated at 90 °C and stirred. As the reaction progressed, urea continuously released OH. -The ions make the pH of the reaction system increase continuously, and the metal ions form a uniform precipitation. When the metal ions are completely precipitated and the pH of the system remains unchanged, stir at a constant temperature of 90 ° C for 4 hours and let it stand at room temperature for 18 hours. (3) Filter the precipitate 3 to 6 times, dry it at 95 °C, and calcine it at 400 °C for 4 h in a nitrogen atmosphere; (4) the solid oxide obtained by calcining in step (3) was reacted in ethanol-water (volume ratio 1:2) at 90°C in a high-pressure reactor for 5 hours; (5) Dry the solid obtained in step (4) under vacuum at 85°C; grind the obtained solid oxide for later use. Example

[0041] A hierarchically porous copper-based solid solution catalyst, wherein, based on the mass of the catalyst being 100%, the CuO content is 23 wt%, the Al2O3 content is 6 wt%, the SiO2 content is 25 wt%, the CeO2 content is 30 wt%, the ZrO2 content is 16 wt%, the pore size distributions of the micropores and mesopores are 0.9 nm and 41 nm, respectively, and the specific surface area is 73 m 2 / g.

[0042] The preparation method of the multi-level porous copper-based solid solution catalyst comprises the following steps: (1) Dissolve 7.22 g CuSO4·5H2O, 2.84 g AlCl3·6H2O, 8.84 g Na2SiO3·5H2O, 5.79 g Ce(SO4)2, and 3.68 g Zr(SO4)2 in water to prepare a mixed solution with a total metal ion concentration of 2.2 mol / L. Add urea (1.4 times the metal ion equivalent) and mix by ultrasonication for 20 min.

[0043] (2) The mixed solution prepared in step (1) is heated at 95°C and stirred. As the reaction progresses, urea continuously releases OH - The ions make the pH of the reaction system increase continuously, and the metal ions form a uniform precipitation. When the metal ions are completely precipitated and the pH of the system remains unchanged, stir at 95 °C for 4 h and let it stand at room temperature for 18 h. (3) Filter the above precipitate 3 to 6 times, dry it at 95 °C, and calcine it at 450 °C for 4 h in a nitrogen atmosphere; (4) the solid oxide obtained by calcining in step (3) was reacted in ethanol-water (volume ratio 1:2) at 90°C in a high-pressure reactor for 8 h; (5) Dry the solid obtained in step (4) under vacuum at 80°C; grind the obtained solid oxide for later use.

[0044] Experimental Example 1 The catalytic performance of the multi-level porous copper-based solid solution catalyst, industrial copper-bismuth catalyst, and copper-based solid base catalyst prepared in Examples 1-6 (the copper-based solid base catalyst was prepared according to Example 1 of Patent No. ZL202211068331.X) was evaluated: 5.0 g of the multi-level porous copper-based solid solution catalyst prepared in the above Examples 1-6 and 50 ml of formaldehyde solution were placed in a slurry bed reactor. Under the conditions of a reaction temperature of 85°C, a reaction pressure of normal pressure, and an acetylene flow rate of 80 ml / min, the catalytic performance and cyclic stability of the multi-level porous copper-based solid solution catalyst in the acetylation reaction were investigated.

[0045]

[0046]

[0047] It can be seen from the evaluation results in Tables 1 and 2 that the hierarchical porous copper-based solid solution catalyst of the present invention has higher acetylation activity and stability.

[0048] The morphology, structure, texture and surface chemical properties of the prepared hierarchical porous copper-based solid solution catalyst were characterized by transmission electron microscopy (TEM), field emission scanning electron microscopy (SEM), X-ray diffraction (XRD), laser Raman spectroscopy (Raman spectrum) and N2 physical adsorption-desorption (N2adsorption-desorption) (see Figures 1 to 6 ). TEM and SEM images show that the prepared copper-based solid solution catalyst is in granular form (see Figure 1 and 2 The XRD spectrum shows that the characteristic diffraction peaks of copper and cerium species in the prepared catalyst are relatively diffuse, indicating that the copper and cerium species are highly dispersed and highly composite (see Figure 3 ).Depend on Figure 4 and 5 The Raman spectrum shown in the figure shows that there are a large number of oxygen vacancies on the surface of the prepared copper-based solid solution catalyst. Figure 6 The hysteresis loop of the physical adsorption / desorption curve shown shows capillary condensation at low pressure and a hysteresis loop at high pressure, indicating the presence of both micropores and mesopores. The pore size distribution plot shows that it corresponds to micropores of 0.6 nm and mesopores of 35 nm.

[0049] The above content is a further detailed description of the present invention in combination with a specific preferred embodiment. It cannot be considered that the specific embodiments of the present invention are limited to this. For ordinary technicians in the technical field to which the present invention belongs, they can make several simple deductions or substitutions without departing from the present invention, which should be regarded as belonging to the scope of patent protection determined by the submitted claims of the present invention.

Claims

1. A multi-level porous copper-based solid solution catalyst, characterized in that: The catalyst surface is rich in synergistic sites of active copper centers and oxygen vacancies, and multi-level pores of micropores and mesopores are distributed inside the catalyst. Based on the mass of the catalyst as 100%, the CuO content is 15-30 wt%, the CeO2 content is 10-30 wt%, the ZrO2 content is 5-20 wt%, the Al2O3 content is 2-10 wt%, and the SiO2 content is 10-30 wt%. The pore size distribution of the multi-level pores of the catalyst, i.e., the micropores and mesopores, is 0.5-1 nm and 25-50 nm, respectively. The specific surface area of the catalyst is 50-150 m 2 / g.

2. The method for preparing a multi-level porous copper-based solid solution catalyst according to claim 1, wherein: The following steps are involved: S1. According to the catalyst composition ratio, copper salt, aluminum salt, silicon source, cerium salt, and zirconium salt are dissolved in water to prepare a mixed solution with a total metal ion concentration of 0.5 to 3.0 mol / L; urea in an amount of 1.2 to 1.6 times the metal ion equivalent is added thereto and mixed thoroughly to obtain a metal ion mixed solution; S2. heating the metal ion mixed solution at 85-95° C. with stirring to allow the metal ions to fully and evenly precipitate; when the metal ions are completely precipitated and the pH of the system remains unchanged, maintaining the temperature and stirring for 2-4 hours, and then allowing to stand at room temperature for 12-18 hours; S3, drying the precipitate obtained in step S2 and calcining it at 300-650° C. in an atmosphere for 2-6 h to obtain a solid oxide; S4, reacting the obtained solid oxide in ethanol-water at 80-100° C. in a high-pressure reactor for 3-8 hours; S5. Drying the reactant obtained in S4 to obtain a multi-level porous copper-based solid solution catalyst.

3. The method for preparing a multi-level porous copper-based solid solution catalyst according to claim 2, characterized in that: The thorough mixing in step S1 is ultrasonic mixing for 15 to 25 minutes.

4. The method for preparing a multi-level porous copper-based solid solution catalyst according to claim 2, wherein: In step S3, the drying step is to filter the precipitate obtained in step S2 3 to 6 times and dry it at 75 to 95°C.

5. The method for preparing a multi-level porous copper-based solid solution catalyst according to claim 2, characterized in that: In step S5, the drying step is to vacuum dry the reactant obtained in step S4 at 75-95°C.

6. The method for preparing a multi-level porous copper-based solid solution catalyst according to claim 2, characterized in that: The copper salt is one of copper nitrate, copper sulfate, and copper chloride, or any combination thereof; the aluminum salt is one of aluminum nitrate, aluminum sulfate, and aluminum chloride, or any combination thereof.

7. The method for preparing a multi-level porous copper-based solid solution catalyst according to claim 2, characterized in that: The silicon source is one or any combination of ethyl silicate, silica sol, and sodium silicate.

8. The method for preparing a multi-level porous copper-based solid solution catalyst according to claim 2, characterized in that: The cerium salt is one of cerium nitrate, cerium sulfate, and cerium chloride, or any combination thereof; the zirconium salt is one of zirconium nitrate, zirconium sulfate, and zirconium chloride, or any combination thereof.

9. The method for preparing a multi-level porous copper-based solid solution catalyst according to claim 2, characterized in that: The atmosphere is one of nitrogen, argon, and helium, or any combination thereof.

10. Use of the hierarchically porous copper-based solid solution catalyst according to claim 1 or the hierarchically porous copper-based solid solution catalyst obtained by the preparation method according to any one of claims 2 to 8 in the synthesis of 1,4-butynediol by formaldehyde ethynylation.

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