Palladium / cobalt aluminum layered double hydroxide composite material and preparation method and application thereof
By loading Pd nanoparticles on cobalt-aluminum layered double hydroxide nanosheets, the problem of easy agglomeration of Pd-based catalysts was solved, and efficient catalytic hydrogenation of 2-methyl-3-butyn-2-ol to methyl-3-butene-2-ol was achieved with high catalytic activity and selectivity.
Patent Information
- Application Number
- CN202510801109.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-16
- Publication Date
- 2025-09-19
AI Technical Summary
Existing Pd-based catalysts have problems such as lead toxicity, support instability, and easy agglomeration of Pd nanoparticles in the selective hydrogenation of alkynes, resulting in low enolate yields and over-hydrogenation side reactions.
Cobalt-aluminum layered double hydroxide nanosheets were used as carriers to load Pd nanoparticles. Palladium/cobalt-aluminum layered double hydroxide composites were prepared by a hydrothermal method and the reducing agent sodium borohydride to avoid Pd nanoparticle agglomeration and improve mass transfer efficiency.
The highly efficient catalytic hydrogenation of 2-methyl-3-butyn-2-ol to methyl-3-butene-2-ol was achieved, with high catalytic activity and selectivity, and reduced deep hydrogenation side reactions of the product.
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Figure CN120662332A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of catalysts, and in particular to a palladium / cobalt aluminum layered double hydroxide composite material, a preparation method and an application thereof. Background Art
[0002] The information disclosed in this background technology section is only intended to enhance understanding of the overall background of the invention and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to those skilled in the art.
[0003] 2-Methyl-3-butene-2-ol, abbreviated as methylbutenol (MBE), is an important intermediate in the production of vitamins, carotenoids and other compounds. It is also used in the synthesis of high-efficiency and low-toxic pesticides such as pyrethroid insecticides, as well as rubber monomers and spices.
[0004] Currently, regarding the preparation method of 2-methyl-3-butene-2-ol, the most commonly used method is to use acetone and acetylene as raw materials, and the two react to obtain 2-methyl-3-butyn-2-ol (abbreviated as methylbutynol (MBY)), which is then semi-hydrogenated to obtain 2-methyl-3-butene-2-ol.
[0005] In industry, the aforementioned semi-hydrogenation reaction is often catalyzed by Lindlar (Pd-Pb / CaCO3) catalysts due to their excellent selectivity for the semi-hydrogenation of alkynols. However, the use of Lindlar (Pd-Pb / CaCO3) catalysts has the following disadvantages, including the toxicity of lead, the necessity of adding quinoline to the reaction, and the instability of the calcium carbonate support, which leads to harmful and irreversible chemical transformations.
[0006] In recent years, heterogeneous noble metal catalysts such as Pd, Pt, and Rh have been developed for the selective hydrogenation of alkynes. Pd-based catalysts offer the best performance (it is generally believed that the adsorption strength of carbon-carbon triple bonds on the Pd surface is stronger than that of carbon-carbon double bonds). However, the high surface energy of Pd nanoparticles due to their nanoscale size effect makes them prone to agglomeration during the reaction. While monometallic Pd offers high conversion rates, it is also prone to side reactions such as overhydrogenation, resulting in low enolate yields. Therefore, an environmentally friendly catalyst with both high activity and selectivity is urgently needed. Summary of the Invention
[0007] In order to overcome the above problems, the present invention provides a palladium / cobalt aluminum layered double hydroxide composite material and a preparation method and application thereof.
[0008] In order to achieve the above technical objectives, the present invention adopts the following technical solutions: The first aspect of the present invention provides a palladium / cobalt aluminum layered double hydroxide composite material, which uses cobalt aluminum layered double hydroxide nanosheets as a carrier and loads Pd nanoparticles; the mass of the Pd nanoparticles accounts for 3-5% of the total mass of the composite material.
[0009] In one or more embodiments, the palladium / cobalt aluminum layered double hydroxide composite material has a spherical structure and a particle size of 7 to 9 μm.
[0010] In one or more embodiments, the particle size of the Pd nanoparticles is 5 to 20 nm.
[0011] The second aspect of the present invention provides a method for preparing the palladium / cobalt aluminum layered double hydroxide composite material described in the first aspect, comprising the following steps: (1) Dissolving ammonium fluoride, urea, cobalt salt, and aluminum salt in deionized water, mixing them evenly, and then performing a hydrothermal reaction to obtain cobalt-aluminum layered double hydroxide nanosheets; (2) Dispersing the cobalt aluminum layered double hydroxide nanosheets in water, adding a palladium salt solution, mixing evenly, adding a reducing agent, sodium borohydride, and after the reaction is completed, centrifuging and collecting the solid to obtain the palladium / cobalt aluminum layered double hydroxide composite material.
[0012] In one or more embodiments, in step (1), the cobalt salt includes one or more of cobalt acetylacetonate, cobalt acetate, cobalt nitrate, cobalt chloride and cobalt fluoride, preferably cobalt nitrate.
[0013] In one or more embodiments, in step (1), the aluminum salt includes one or more of aluminum sulfate, aluminum nitrate and aluminum chloride, preferably aluminum nitrate.
[0014] In one or more embodiments, in step (1), the molar ratio of ammonium fluoride, urea, cobalt salt, and aluminum salt is: (4.5-7): (18-30): (2.5-5): (0.8-2.5). Under these ratios, cobalt-aluminum layered double hydroxide nanosheets can be obtained.
[0015] In one or more embodiments, in step (1), the hydrothermal reaction temperature is 140-160° C., and the hydrothermal reaction time is 16-20 h. Under these reaction conditions, cobalt-aluminum layered double hydroxide nanosheets can be obtained.
[0016] In one or more embodiments, in step (2), the palladium salt includes any one of palladium chloride and palladium acetate.
[0017] In one or more embodiments, in step (2), the concentration of the palladium salt solution is 0.05-0.07 mol / L. Under these reaction conditions, the Pd nanoparticles can be uniformly dispersed on the cobalt aluminum layered double hydroxide nanosheets.
[0018] In one or more embodiments, in step (2), the molar ratio of palladium salt to sodium borohydride is (1-1.3): (2-3). Under this condition, uniformly dispersed Pd nanoparticles can be obtained.
[0019] In one or more embodiments, in step (2), sodium borohydride is added as a reducing agent, and the reaction time is 1.5 to 3 hours. Under these conditions, uniformly dispersed Pd nanoparticles can be obtained.
[0020] The third aspect of the present invention provides the use of the palladium / cobalt aluminum layered double hydroxide composite material described in the first aspect or the palladium / cobalt aluminum layered double hydroxide composite material prepared by the preparation method described in the second aspect as a catalyst; The application includes: catalyzing the hydrogenation of 2-methyl-3-butyn-2-ol to synthesize methyl-3-butene-2-ol.
[0021] A fourth aspect of the present invention provides a method for synthesizing methyl-3-butene-2-ol, comprising: dispersing a raw material, 2-methyl-3-butyn-2-ol, in an organic solvent; using the palladium / cobalt aluminum layered double hydroxide composite material described in the first aspect or the palladium / cobalt aluminum layered double hydroxide composite material prepared by the preparation method described in the second aspect as a catalyst; and introducing hydrogen to react to obtain methyl-3-butene-2-ol.
[0022] In one or more embodiments, the organic solvent is an alcohol, preferably ethanol. Selecting such a solvent can achieve a good dispersion effect and increase the reaction rate.
[0023] In one or more embodiments, the hydrogen pressure is 0.5-2 MPa. Under this condition, the reaction rate is high and the reaction selectivity is high.
[0024] In one or more embodiments, the reaction temperature is 50-120° C. Under these conditions, the reaction rate is high and the reaction selectivity is high.
[0025] In one or more embodiments, the reaction time is 1 to 6 hours. Under these conditions, the reaction rate is high and the reaction selectivity is high.
[0026] The beneficial effects of the present invention are: In the present invention, cobalt-aluminum layered double hydroxide nanosheets are used as carriers, and Pd nanoparticles are loaded to obtain a palladium / cobalt-aluminum layered double hydroxide composite material. The palladium / cobalt-aluminum layered double hydroxide composite material not only has efficient catalytic activity when catalyzing 2-methyl-3-butyn-2-ol hydrogenation to synthesize methyl-3-butene-2-ol, but also has efficient selectivity. This is because the layered double hydroxide nanosheets, due to their unique layered structure, can avoid the agglomeration of Pd nanoparticles, while accelerating the mass transfer efficiency of 2-methyl-3-butyn-2-ol and hydrogen, reducing the residence time of the product 2-methyl-3-butene-2-ol and hydrogen, avoiding deep hydrogenation of the product, and then improving the selectivity of the catalyst. BRIEF DESCRIPTION OF THE DRAWINGS
[0027] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.
[0028] Figure 1 Figures a and b are scanning electron microscope images of the palladium / cobalt aluminum layered double hydroxide composite material prepared in Example 1; Figure 2 2 is the XRD pattern of the palladium / cobalt aluminum layered double hydroxide composite material prepared in Example 1. DETAILED DESCRIPTION
[0029] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.
[0030] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.
[0031] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.
[0032] Example 1 Synthesis of palladium / cobalt aluminum layered double hydroxide composites: (1) 0.05 mol ammonium fluoride, 0.2 mol urea, 0.03 mol cobalt nitrate and 0.01 mol aluminum nitrate were dissolved in 100 mL deionized water and stirred for 30 min to form a uniform mixed solution. The mixed solution was transferred to a 150 mL reactor and subjected to hydrothermal reaction at 150 °C for 18 h. After the reaction, the reactor was naturally cooled to room temperature. The obtained product was centrifuged, washed with deionized water and ethanol three times each, and finally dried at 70 °C for 12 h to obtain cobalt aluminum layered double hydroxide nanosheets Co-Al LDH. (2) 5 g of the cobalt aluminum layered double hydroxide nanosheets prepared in step (1) were dispersed in 100 mL of deionized water to form a Co-Al LDH suspension; 0.2 g of palladium chloride was weighed and dissolved in 20 mL of deionized water to form a palladium salt solution; the palladium salt solution was slowly added dropwise to the Co-Al LDH suspension while stirring, and the addition time was 30 min; after the addition was completed, the stirring was continued for 3 h; then 0.1 g of sodium borohydride was added to the mixed system, and the reduction reaction was carried out at room temperature for 2 h; after the reaction was completed, the product was centrifuged, washed with deionized water and ethanol 3 times each, and finally dried at 70 ° C for 12 h to obtain a palladium / cobalt aluminum layered double hydroxide composite material. After testing, the palladium loading was 4%.
[0033] Figure 1 The scanning electron microscope image of the palladium / cobalt aluminum layered double hydroxide composite material prepared in this example is shown in FIG. Figure 1 It can be seen that the cobalt-aluminum layered double hydroxide is a nanosheet material, and Pd nanoparticles are uniformly loaded on the cobalt-aluminum layered double hydroxide nanosheets.
[0034] Figure 2 The XRD pattern of the palladium / cobalt aluminum layered double hydroxide composite material prepared in this embodiment is shown in FIG. Figure 2 It can be seen that the XRD diffraction peaks are highly consistent with the CoAl-LDH#51-0045 standard card, which fully confirms the successful synthesis of LDH.
[0035] Example 2 Synthesis of palladium / cobalt aluminum layered double hydroxide composites: (1) 0.05 mol ammonium fluoride, 0.2 mol urea, 0.03 mol cobalt nitrate and 0.01 mol aluminum nitrate were dissolved in 100 mL deionized water and stirred for 30 min to form a uniform mixed solution. The mixed solution was transferred to a 150 mL reactor and subjected to hydrothermal reaction at 150 °C for 18 h. After the reaction, the reactor was naturally cooled to room temperature. The obtained product was centrifuged, washed with deionized water and ethanol three times each, and finally dried at 70 °C for 12 h to obtain cobalt aluminum layered double hydroxide nanosheets Co-Al LDH. (2) 5 g of the cobalt aluminum layered double hydroxide nanosheets prepared in step (1) were dispersed in 100 mL of deionized water to form a Co-Al LDH suspension; 0.2 g of palladium chloride was weighed and dissolved in 20 mL of deionized water to form a palladium salt solution; the palladium salt solution was slowly added dropwise to the Co-Al LDH suspension while stirring, and the addition time was 30 min; after the addition was completed, the stirring was continued for 3 h; then 0.09 g of sodium borohydride was added to the mixed system, and the reduction reaction was carried out at room temperature for 2 h; after the reaction was completed, the product was centrifuged, washed with deionized water and ethanol 3 times each, and finally dried at 70 ° C for 12 h to obtain a palladium / cobalt aluminum layered double hydroxide composite material. After testing, the palladium loading was 3%.
[0036] Example 3 Synthesis of palladium / cobalt aluminum layered double hydroxide composites: (1) 0.06 mol ammonium fluoride, 0.25 mol urea, 0.04 mol cobalt nitrate and 0.02 mol aluminum nitrate were dissolved in 120 mL deionized water and stirred for 40 min to form a uniform mixed solution. The mixed solution was transferred to a 180 mL reactor and subjected to hydrothermal reaction at 160 °C for 20 h. After the reaction, the reactor was naturally cooled to room temperature. The obtained product was centrifuged, washed with deionized water and ethanol four times each, and finally dried at 75 °C for 12 h to obtain cobalt aluminum layered double hydroxide nanosheets Co-Al LDH. (2) 6 g of the cobalt aluminum layered double hydroxide nanosheets prepared in step (1) were dispersed in 120 mL of deionized water to form a Co-Al LDH suspension; 0.3 g of palladium chloride was weighed and dissolved in 25 mL of deionized water to form a palladium salt solution; the palladium salt solution was slowly added dropwise to the Co-Al LDH suspension while stirring, and the addition time was 40 min; after the addition was completed, the stirring was continued for 3 h; then 0.15 g of sodium borohydride was added to the mixed system, and a reduction reaction was carried out at 40 °C for 2.5 h; after the reaction was completed, the product was centrifuged, washed with deionized water and ethanol three times each, and finally dried at 75 °C for 14 h to obtain a palladium / cobalt aluminum layered double hydroxide composite material. After testing, the palladium loading was 5%.
[0037] Comparative Example 1 0.05 mol ammonium fluoride, 0.2 mol urea, 0.03 mol cobalt nitrate, and 0.01 mol aluminum nitrate were dissolved in 100 mL of deionized water and stirred for 30 min to form a uniform mixed solution. The mixed solution was transferred to a 150 mL reactor and subjected to a hydrothermal reaction at 150 °C for 18 h. After the reaction, the reactor was naturally cooled to room temperature, and the obtained product was centrifuged, washed with deionized water and ethanol three times each, and finally dried at 70 °C for 12 h to obtain cobalt-aluminum layered double hydroxide nanosheets Co-Al LDH.
[0038] Comparative Example 2 Pd / Al2O3 prepared by traditional impregnation method: 6 g of Al2O3 powder was dispersed in 120 mL of deionized water to form an Al2O3 suspension. 0.3 g of palladium chloride was weighed and dissolved in 25 mL of deionized water to form a palladium salt solution. The palladium salt solution was slowly added dropwise to the Al2O3 suspension with stirring for 40 minutes. After the addition was complete, stirring was continued for 3 hours. 0.15 g of sodium borohydride was then added to the mixture, and a reduction reaction was carried out at 40°C for 2.5 hours. After the reaction, the product was centrifuged, washed three times with deionized water and ethanol, and finally dried at 75°C for 14 hours to obtain a Pd / Al2O3 composite material. Testing showed that the palladium loading was 4%.
[0039] Experimental Example 1 The palladium / cobalt aluminum layered double hydroxide composite materials prepared in Examples 1 to 3, and the materials in Comparative Example 1 and Comparative Example 2 were respectively used as catalysts to catalyze the hydrogenation of 2-methyl-3-butyn-2-ol to 2-methyl-3-butene-2-ol.
[0040] The reaction synthesis conditions are: 25 g of 2-methyl-3-butyn-2-ol was dispersed in 120 mL of ethanol, 1.2 g of catalyst was added, and hydrogen (pressure 1.2 MPa) was passed through at 80 °C for 4 h. After the reaction, the reaction product was detected by gas chromatography.
[0041] The results are shown in Table 1. As can be seen from Table 1, the palladium / cobalt aluminum layered double hydroxide composite material prepared in Example 1 exhibits optimal catalytic performance, with a conversion of 91.30% for 2-methyl-3-butyn-2-ol and a selectivity of 92.30% for the target product, 2-methyl-3-butene-2-ol. In Examples 1 to 3, a Pd loading of 3% resulted in insufficient active sites, leading to a low conversion rate. At a Pd loading of 5%, Pd particles easily agglomerated, reducing dispersion. Although the conversion rate was slightly higher, selectivity decreased. Excessive Pd loadings resulted in overcrowding of active sites on the catalyst surface, making it prone to excessive hydrogenation or other side reactions during adsorption and reaction of reactant molecules on the catalyst surface. A Pd loading of 4% provided the optimal number of active sites and dispersion, ensuring efficient hydrogenation while suppressing side reactions.
[0042] In Comparative Example 1, the layered double hydroxide nanosheets alone had almost no catalytic effect.
[0043] Catalytic performance of the catalyst prepared in Comparative Example 2: the conversion rate of 2-methyl-3-butyn-2-ol was 65.6%, and the selectivity of the target product 2-methyl-3-butene-2-ol was 60.9%.
[0044] The above results show that the palladium / cobalt aluminum layered double hydroxide composite material not only exhibits high catalytic activity but also high selectivity when catalyzing the hydrogenation of 2-methyl-3-butyn-2-ol to methyl-3-butene-2-ol. This is because the layered double hydroxide nanosheets, due to their unique layered structure, can prevent the agglomeration of Pd nanoparticles, while also accelerating the mass transfer efficiency between 2-methyl-3-butyn-2-ol and hydrogen, reducing the residence time of 2-methyl-3-butene-2-ol and hydrogen, and thus improving selectivity.
[0045] Table 1 Catalytic results of catalysts in Examples 1-3 and Comparative Examples 1-2
[0046] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.
Claims
1. A palladium / cobalt aluminum layered double hydroxide composite material, characterized in that The composite material uses cobalt-aluminum layered double hydroxide nanosheets as a carrier and loads Pd nanoparticles; the mass of the Pd nanoparticles accounts for 3-5% of the total mass of the composite material.
2. The palladium / cobalt aluminum layered double hydroxide composite material according to claim 1, wherein The palladium / cobalt aluminum layered double hydroxide composite material has a spherical structure and a particle size of 7 to 9 μm; Alternatively, the particle size of the Pd nanoparticles is 5 to 20 nm.
3. The method for preparing the palladium / cobalt aluminum layered double hydroxide composite material according to claim 1 or 2, wherein: The following steps are involved: (1) Dissolving ammonium fluoride, urea, cobalt salt, and aluminum salt in deionized water, mixing them evenly, and then performing a hydrothermal reaction to obtain cobalt-aluminum layered double hydroxide nanosheets; (2) Dispersing the cobalt aluminum layered double hydroxide nanosheets in water, adding a palladium salt solution, mixing evenly, adding a reducing agent, sodium borohydride, and after the reaction is completed, centrifuging and collecting the solid to obtain the palladium / cobalt aluminum layered double hydroxide composite material.
4. The preparation method according to claim 1, wherein In step (1), the cobalt salt includes one or a combination of dicobalt octacarbonyl, cobalt acetylacetonate, cobalt acetate, cobalt nitrate, cobalt bromide, cobalt fluoride, and cobalt tetrafluoroborate, preferably cobalt nitrate; Alternatively, in step (1), the aluminum salt includes one or more of aluminum sulfate, aluminum nitrate, and aluminum chloride, preferably aluminum nitrate.
5. The preparation method according to claim 1, wherein In step (1), the molar ratio of ammonium fluoride, urea, cobalt salt and aluminum salt is: (4.5-7): (18-30): (2.5-5): (0.8-2.5).
6. The preparation method according to claim 1, wherein In step (1), the temperature of the hydrothermal reaction is 140-160° C.; the time of the hydrothermal reaction is 16-20 h.
7. The preparation method according to claim 1, wherein In step (2), the palladium salt includes any one of palladium chloride and palladium acetate; Or, in step (2), the concentration of the palladium salt solution is 0.05-0.07 mol / L; Or, in step (2), the molar ratio of palladium salt to sodium borohydride is (1-1.3):(2-3); Alternatively, in step (2), sodium borohydride is added as a reducing agent, and the reaction time is 1.5 to 3 hours.
8. Use of the palladium / cobalt aluminum layered double hydroxide composite material according to claim 1 or 2 or the palladium / cobalt aluminum layered double hydroxide composite material prepared by the preparation method according to any one of claims 3 to 7 as a catalyst; The applications include: Catalyzes the hydrogenation of 2-methyl-3-butyn-2-ol to synthesize methyl-3-butene-2-ol.
9. A method for synthesizing methyl-3-butene-2-ol, characterized in that: include: The raw material 2-methyl-3-butyn-2-ol is dispersed in an organic solvent, and the palladium / cobalt aluminum layered double hydroxide composite material according to claim 1 or 2 or the palladium / cobalt aluminum layered double hydroxide composite material prepared by the preparation method according to any one of claims 3 to 7 is used as a catalyst, and hydrogen is introduced to react to obtain methyl-3-butene-2-ol.
10. The method according to claim 9, wherein The organic solvent is an alcohol, preferably ethanol; Alternatively, the hydrogen pressure is 0.5~2 MPa; Alternatively, the reaction temperature is 50-120°C; Alternatively, the reaction time is 1 to 6 h.