Amino silicon dioxide sphere supported palladium catalyst as well as preparation method and application thereof
By dispersing palladium atomically at the surface of amino silica spheres, an amino silica sphere-supported palladium catalyst was prepared, which solved the problems of low selectivity and high cost in the selective hydrogenation reaction of existing palladium nanoparticle catalysts in acetylene, and achieved efficient and stable catalytic performance and long-life catalysts.
Patent Information
- Application Number
- CN202411680746.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-22
- Publication Date
- 2025-02-25
AI Technical Summary
The existing palladium nanoparticle catalysts have excessive hydrogenation side reactions in acetylene selective hydrogenation reaction, which reduces the selectivity of the reaction, and the high cost of palladium limits its wide application.
Amino silica spheres were prepared by sol-gel method using amino silica spheres to support palladium catalysts, and the palladium atomic fraction was dispersed on the surface of amino silica spheres by impregnation and reduction methods.
The catalyst exhibits excellent selectivity and stability in the acetylene hydrogenation reaction, with acetylene conversion rate reaching 100%, an ethylene selectivity of 92%, and can be used continuously at 180°C for 35 hours, which significantly improves the efficiency of the catalytic reaction and the service life of the catalyst.
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Figure CN119500275A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of catalysts for selective hydrogenation of acetylene, and in particular to an aminosilica ball-supported palladium catalyst and a preparation method and application thereof. Background Art
[0002] Ethylene is known as the "mother of petrochemical industry" and is the basic raw material of the global chemical industry. Most ethylene production relies on the steam cracking process of naphtha and ethane. In this process, naphtha and ethane are cracked into ethylene and other by-products under high temperature and catalyst, and trace amounts of acetylene are also produced. Since these trace acetylene will poison the downstream ethylene polymerization catalyst, effective measures must be taken to remove acetylene. Selective hydrogenation of acetylene is one of the most effective technologies for purifying ethylene, among which supported palladium nanoparticle catalysts have attracted widespread attention due to their excellent catalytic activity. However, the strong adsorption of palladium nanoparticles on unsaturated reactants or intermediates may lead to excessive hydrogenation side reactions and reduce the selectivity of the reaction. In recent years, atomically dispersed metal catalysts have become a hot topic of research due to their maximum atomic utilization and unique electronic structure. Studies have shown that atomically dispersed palladium metal catalysts can change the adsorption mode of ethylene on palladium active sites, thereby affecting its desorption energy. In addition, due to the high cost of palladium metal, the development of atomically dispersed metal catalysts with higher cost performance has become a current research trend. Summary of the invention
[0003] The purpose of the present invention is to provide an aminosilica ball-supported palladium catalyst and a preparation method and application thereof. The aminosilica ball-supported palladium catalyst prepared by the method exhibits excellent selectivity and stability in the acetylene hydrogenation reaction, thereby effectively improving the efficiency of the catalytic reaction and the service life of the catalyst.
[0004] To achieve the above purpose, the technical solution of the present invention is as follows:
[0005] The invention discloses an aminosilica ball-loaded palladium catalyst. The catalyst uses palladium as an active material and aminosilica balls as a carrier. The palladium is dispersed on the surface of the aminosilica balls in an atomic-level form.
[0006] In this catalyst, the surface of aminosilica spheres is rich in amino functional groups, which help to stabilize the anchoring of palladium atoms. Palladium is dispersed on the surface of aminosilica spheres in atomic form and forms coordination bonds with nitrogen atoms on the amino groups.
[0007] Furthermore, the loading amount of palladium is 0.005-0.5wt%, preferably 0.005-0.02wt%; the particle size of the aminosilica spheres is 22-42nm; the nitrogen content of the aminosilica spheres is 1.73-3.2%, preferably 3.04-3.2%.
[0008] The preparation method of the aminosilica ball-supported palladium catalyst comprises the following steps:
[0009] (1) Preparation of amino silica spheres by sol-gel method:
[0010] Take ethanol and ammonia water in a container, stir and react at room temperature, add tetraethyl orthosilicate (TEOS) into the container, stir and react at room temperature; add 3-aminopropyltriethoxysilane (APTES) ethanol solution dropwise into the reaction container, stir and react; after the reaction is completed, separate the solid and liquid, rinse with ethanol, dry and grind to obtain amino silica spheres (SiO 2 -NH 2 );
[0011] (2) Preparation of aminosilica sphere-supported palladium catalyst precursor by impregnation method:
[0012] Put ethanol in a container, calculate the amount of palladium metal salt according to the palladium loading, and weigh the palladium metal salt in ethanol; add amino silica ball carrier to the container, stir to react, separate the solid and liquid after the reaction is completed, and rinse with ethanol and dry;
[0013] (3) Reduction of aminosilica sphere-supported palladium catalyst precursor:
[0014] The aminosilica sphere-supported palladium catalyst precursor is reduced in a hydrogen or hydrogen and helium mixed atmosphere, and then cooled in an inert gas after reduction to obtain an aminosilica sphere-supported palladium catalyst.
[0015] Furthermore, the mass concentration of the ammonia water in step (1) is 26-28%; the volume ratio of ethanol, ammonia water, TEOS and APTES is: 400:10-30:10-30:1-5; the reaction time of ethanol and ammonia water is 20-40 minutes; the reaction time after adding TEOS is 12-36 hours; the reaction temperature after adding the ethanol solution of APTES is 40-90°C, and the reaction time is 12-36 hours.
[0016] Furthermore, the palladium metal salt described in step (2) is Pd(NO 3 ) 2 , PdSO 4 , Pd(NH 3 ) 4 SO 4 , Pd(NH 3 ) 4 (NO 3 ) 2 and Pd(NH 3 ) 4 CO 3one of the above; the concentration of the palladium metal salt solution is 0.1-0.2 g / mL; the mass of the aminosilica sphere carrier is 50-150 mg; and the reaction time is 4-8 h.
[0017] Furthermore, in the hydrogen or hydrogen and helium mixed atmosphere described in step (3), the gas volume fraction of hydrogen is 10 to 100%, and the flow rate of the mixed gas is 10 to 60 mL / min; the reduction temperature is 100 to 300° C., and the reduction time is 10 to 120 min; in the inert gas, the gas flow rate is 15 to 50 mL / min.
[0018] The aminosilica ball-supported palladium catalyst is used as a catalyst in the selective hydrogenation reaction of acetylene. The reaction is carried out in a fixed bed reactor under normal pressure, the catalyst is used at a temperature of 100-200° C., the mixed raw gas flow rate is 10-60 mL / min, and the mixed raw gas composition is: 1-3 vol.%, 10-14 vol.%, ethylene 20-25 vol.%, and the rest is helium as a balance gas.
[0019] The catalyst was used for acetylene hydrogenation reaction, and the acetylene conversion rate reached 100% and the ethylene selectivity was 92% at 190°C. The catalyst could be used stably for up to 35 hours at a reaction temperature of 180°C, showing good catalytic performance and durability.
[0020] The advantages of the present invention are as follows:
[0021] 1. Aminosilica spheres (SiO 2 -NH 2 ), and systematically studied the optimal amount of 3-aminopropyltriethoxysilane (APTES) required to modify the amino group on the surface of silica spheres, providing sufficient amino groups for the subsequent loading of Pd, so that palladium is dispersed in atomic form on the surface of amino silica spheres and forms coordination bonds with the nitrogen atoms on the amino groups.
[0022] 2. A palladium catalyst (Pd 1 / SiO 2 -NH 2 ), and the construction of the catalyst was verified using a spherical aberration electron microscope. The performance of the catalyst in the selective hydrogenation of acetylene was further explored. The results showed that the catalyst exhibited excellent selectivity and high acetylene conversion in the acetylene hydrogenation reaction. The acetylene conversion rate gradually increased from 110°C to 190°C. At 190°C, the acetylene conversion rate reached 100% and the ethylene selectivity was 92%.
[0023] 3. The present invention uses aminosilica ball-supported palladium catalyst as a catalyst for acetylene hydrogenation reaction. The catalyst exhibits excellent cycle stability, and the catalyst can be used continuously for 35 hours at a reaction temperature of 180°C without performance degradation.
[0024] 4. Compared with traditional palladium-based carbon materials and commercial palladium catalysts, the catalyst used in the present invention exhibits a more efficient acetylene conversion rate and excellent ethylene selectivity. The production process is mature, the preparation method is simple and low-cost, and is suitable for large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS
[0025] Figure 1 This is a HAADF-TEM image of the aminosilica sphere-supported palladium single-atom catalyst prepared in Example 6;
[0026] Figure 2 This is the HAADF-TEM image of the aminosilica sphere-supported palladium nanocluster catalyst prepared in Comparative Example 1. DETAILED DESCRIPTION
[0027] The present invention is described in detail below with reference to the accompanying drawings and embodiments.
[0028] The ethanol used in the following examples and comparative examples is analytical grade ethanol.
[0029] Example 1
[0030] Take 30mL of ethanol in a flask, add 1.5mL of 28% ammonia water, and stir at room temperature for 20 minutes to ensure that the solution is evenly mixed. Add 2mL of tetraethyl orthosilicate (TEOS) to the mixed solution and stir at room temperature for 24 hours to promote the reaction. Dissolve 100μL of 3-aminopropyltriethoxysilane (APTES) in 10mL of ethanol, add the solution dropwise to the above flask, and stir at 50°C for 24 hours to complete the surface modification. After the reaction is completed, the solid product is obtained by centrifugation, and the solid product is rinsed with ethanol to effectively remove impurities. The rinsed solid product is placed in an oven at 80°C and dried for 12 hours.
[0031] Example 2
[0032] The operation process is the same as that of Example 1, the only difference being that the volume of 3-aminopropyltriethoxysilane (APTES) added is 200 μL.
[0033] Example 3
[0034] The operation process is the same as that of Example 1, the only difference being that the volume of 3-aminopropyltriethoxysilane (APTES) added is 300 μL.
[0035] Example 4
[0036] The operation process is the same as that of Example 1, the only difference being that the volume of 3-aminopropyltriethoxysilane (APTES) added is 400 μL.
[0037] Example 5
[0038] The operation process is the same as that of Example 1, the only difference being that the volume of 3-aminopropyltriethoxysilane (APTES) added is 500 μL.
[0039] The dried products in Examples 1-5 were subjected to X-ray photoelectron spectroscopy (XPS) analysis, and the nitrogen contents of the products prepared with 5 different volumes of APTES were 1.73%, 3.04%, 2.83%, 3.05%, and 3.2%, respectively. As the amount of APTES increased from 100 μL to 500 μL, the nitrogen content showed a trend of first increasing and then stabilizing. When the amount of APTES reached 200 μL, the nitrogen content was 3.04%, and the nitrogen content remained basically unchanged despite the continued increase in the amount of APTES. Therefore, 200 μL of APTES was selected for subsequent experiments.
[0040] Example 6
[0041] (1) Preparation of amino silica spheres
[0042] The technical solution of Example 2 is used to prepare aminosilica balls. The specific process is as follows: take 30mL of ethanol in a flask, add 1.5mL of ammonia water with a mass concentration of 28%, and stir at room temperature for 20 minutes to ensure that the solution is evenly mixed. Add 2mL of tetraethyl orthosilicate (TEOS) to the mixed solution and stir at room temperature for 24 hours to promote the reaction. Dissolve 200μL of 3-aminopropyltriethoxysilane (APTES) in 10mL of ethanol, add the solution dropwise to the above flask, and stir at 50°C for 24 hours after the addition to complete the surface modification. After the reaction is completed, a solid product is obtained by centrifugation, and the solid product is rinsed with ethanol to effectively remove impurities. The rinsed solid product is placed in an oven at 80°C and dried for 12 hours. After drying, it is taken out and ground to obtain aminosilica balls with a particle size distribution of 22 to 42nm as a carrier, recorded as SiO 2 -NH 2 .
[0043] (2) Preparation of aminosilica sphere-supported palladium-based metal catalyst precursor
[0044] Add 5 mL of ethanol to the beaker, calculate the amount of palladium nitrate solution required based on the palladium loading of 0.02 wt% in the catalyst, and measure Pd(NO 3 ) 2Solution in the above ethanol. Then add 100 mg of aminosilica ball carrier and place it on a stirrer for stirring to ensure uniform dispersion. Keep stirring for 6 hours to promote uniform distribution and adsorption of palladium precursor. After stirring, separate the solid from the solution by filtration and rinse the solid with an appropriate amount of ethanol to remove unreacted substances and impurities. Dry the obtained solid in a constant temperature oven at 80°C for 12 hours to ensure that all solvents evaporate and obtain a dried product.
[0045] (3) Reduction of aminosilica ball-supported palladium-based metal catalyst precursor: The dried product was placed in a quartz tube, reacted at 150°C for 10 minutes in a mixed atmosphere of hydrogen and helium at a flow rate of 20 mL / min (hydrogen gas volume fraction was 10%), and then slowly cooled to room temperature in a 20 mL / min helium atmosphere. The aminosilica ball-supported palladium single atom catalyst was obtained, denoted as Pd 1 / SiO 2 -NH 2 .
[0046] Comparative Example 1
[0047] (1) Preparation of amino silica spheres
[0048] The preparation method is the same as Example 6
[0049] (2) Preparation of aminosilica sphere-supported palladium nanocluster catalyst precursor
[0050] Add 5 mL of ethanol to the beaker, calculate the amount of palladium nitrate solution required based on the palladium loading of 0.5 wt% in the catalyst, and measure Pd(NO 3 ) 2 Solution in the above ethanol. Then add 100 mg of aminosilica ball carrier and place it on a stirrer for stirring to ensure uniform dispersion. Keep stirring for 6 hours to promote uniform distribution and adsorption of palladium precursor. After stirring, separate the solid from the solution by filtration, and rinse the solid with an appropriate amount of ethanol to remove unreacted substances and impurities. Finally, dry the obtained solid in a constant temperature oven at 80°C for 12 hours to ensure that all solvents evaporate and obtain a dried product.
[0051] (3) Reduction of aminosilica ball-supported palladium nanocluster catalyst precursor: The dried product was placed in a quartz tube, reacted at 150°C for 10 minutes in a mixed atmosphere of hydrogen and helium at a flow rate of 20 mL / min (hydrogen gas volume fraction was 10%), and then slowly cooled to room temperature in a 20 mL / min helium atmosphere. The aminosilica ball-supported palladium nanocluster catalyst was obtained, denoted as Pd n / SiO 2 -NH 2 .
[0052] The catalysts prepared in Example 6 and Comparative Example 1 were observed by transmission electron microscopy using a spherical aberration corrected high-angle annular dark field-scanning transmission electron microscopy (HAADF-STEM) (see Figure 1 and Figure 2 ), it can be clearly found that Pd n / SiO 2 -NH 2 Most of the palladium in the catalyst is uniformly distributed on the support in the form of nanoclusters, while Pd 1 / SiO 2 -NH 2 The palladium in the catalyst is highly dispersed on the carrier in the form of single atoms, and according to the detection of nitrogen content in Example 2, it can be shown that there are a large number of amino functional groups on the surface of the amino silica spheres, and the nitrogen atoms on the amino groups have a pair of lone electrons. The palladium metal is dispersed on the surface of the amino silica spheres in the form of atoms and forms a coordination bond with the nitrogen atoms on the amino groups. This significant difference reveals the difference in the dispersion morphology of palladium between the two catalysts, and provides important microstructural information for the subsequent catalytic performance analysis.
[0053] Application Example 1
[0054] Selective hydrogenation of acetylene: 5 mg of the catalyst prepared in Example 6 and Comparative Example 1 were added to a fixed bed reactor respectively. A mixed raw gas was introduced, which consisted of 1 vol.% acetylene, 10 vol.% hydrogen, 20 vol.% ethylene, and the rest was helium as a balance gas. In a 20 mL / min reaction gas atmosphere, the temperature of the fixed bed reactor was set between 100°C and 200°C. The reaction products were analyzed and detected by gas chromatography, with samples taken every 10°C and stabilized at each temperature for 45 minutes. The results showed that Pd n / SiO 2 -NH 2 Although the acetylene conversion rate of the catalyst reached 100%, the ethylene selectivity was less than 50%. 1 / SiO 2 -NH 2 When the catalyst is at 180°C, the conversion rate of acetylene reaches 100% and the selectivity of ethylene is 90%; when it is at 190°C, the conversion rate of acetylene reaches 100% and the selectivity of ethylene is 92%.
[0055] Application Example 2
[0056] Catalyst stability test: 5 mg of the catalyst prepared in Example 6 was added to a fixed bed reactor. A mixed raw gas was introduced, which consisted of 1 vol.% acetylene, 10 vol.% hydrogen, 20 vol.% ethylene, and the rest was helium as a balance gas. In a 20 mL / min reaction gas atmosphere, the temperature of the fixed bed reactor was set at 180°C. The reaction product was analyzed and detected by gas chromatography, and samples were taken every 25 minutes for 35 hours. The catalyst did not show obvious performance degradation after continuous use at 180°C for 35 hours.
[0057] According to the results of the selective hydrogenation reaction of acetylene, the Pd n / SiO 2 -NH 2 The catalyst showed poor ethylene selectivity. 1 / SiO 2 -NH 2 The catalyst exhibits a higher acetylene conversion rate and excellent ethylene selectivity. This indicates that the aminosilica sphere-supported atomically dispersed palladium catalyst of the present invention has significant catalytic activity and selectivity in the acetylene hydrogenation reaction, and can significantly improve the acetylene conversion rate and ethylene selectivity.
[0058] The catalyst can achieve 100% acetylene conversion and 92% ethylene selectivity at 190°C. There is no obvious performance degradation after continuous use at 180°C for 35 hours. In addition, the catalyst has a mature synthesis method and a simple and easy-to-implement modification process, which further enhances its feasibility and advantages in practical applications.
[0059] The above are preferred embodiments of the present invention, but the protection scope of the present invention is not limited to these embodiments. Various modifications and changes made by those skilled in the art to the present invention should also be included in the protection scope of the present invention.
Claims
1. An aminosilica ball-supported palladium catalyst, characterized in that: Palladium is used as the active material and aminosilica spheres are used as carriers, and palladium is dispersed on the surface of aminosilica spheres in the form of atoms.
2. The aminosilica ball-supported palladium catalyst according to claim 1, characterized in that: The surface of the aminosilica sphere is rich in amino functional groups, and palladium is dispersed on the surface of the aminosilica sphere in the form of atoms and forms coordination bonds with nitrogen atoms on the amino groups.
3. The aminosilica ball-supported palladium catalyst according to claim 1, characterized in that: In the catalyst, the palladium loading is 0.005-0.5wt%, preferably 0.005-0.02wt%; the particle size of the aminosilica sphere is 22-42nm; the nitrogen content of the aminosilica sphere is 1.73-3.2%, preferably 3.04-3.2%.
4. A method for preparing an aminosilica sphere-supported palladium catalyst according to any one of claims 1 to 3, characterized in that: The steps include: (1) Preparation of amino silica spheres by sol-gel method: Put ethanol and ammonia water in a container, stir and react at room temperature, add tetraethyl orthosilicate (TEOS) into the container, stir and react at room temperature; dropwise add 3-aminopropyltriethoxysilane (APTES) ethanol solution into the reaction container, stir and react; after the reaction is completed, separate the solid and liquid, rinse with ethanol, dry and grind to obtain amino silica spheres (SiO2-NH2); (2) Preparation of aminosilica sphere-supported palladium catalyst precursor by impregnation method: Put ethanol in a container, calculate the amount of palladium metal salt according to the palladium loading, and measure the palladium metal salt solution in ethanol; add amino silica ball carrier to the container, stir to react, separate the solid and liquid after the reaction is completed, and rinse with ethanol and dry; (3) Reduction of aminosilica sphere-supported palladium catalyst precursor: The aminosilica sphere-supported palladium catalyst precursor is reduced in a hydrogen or hydrogen and helium mixed atmosphere, and then cooled in an inert gas after reduction to obtain an aminosilica sphere-supported palladium catalyst.
5. The method for preparing an aminosilica ball-supported palladium catalyst according to claim 4, wherein: The mass concentration of the ammonia water in step (1) is 26-28%; the volume ratio of the ethanol, ammonia water, TEOS and APTES is 400:10-30:10-30:1-5; the reaction time of ethanol and ammonia water is 20-40 minutes; the reaction time after adding TEOS is 12-36 hours; the reaction temperature after adding the ethanol solution of APTES is 40-90°C, and the reaction time is 12-36 hours.
6. The method for preparing an aminosilica ball-supported palladium catalyst according to claim 4, wherein: The palladium metal salt described in step (2) is one of Pd(NO3)2, PdSO4, Pd(NH3)4SO4, Pd(NH3)4(NO3)2 and Pd(NH3)4CO3; the concentration of the palladium metal salt solution is 0.1-0.2 g / mL; the mass of the aminosilica sphere carrier is 50-150 mg; and the reaction time is 4-8 h.
7. The method for preparing an aminosilica ball-supported palladium catalyst according to claim 4, wherein: In the hydrogen or hydrogen and helium mixed atmosphere described in step (3), the gas volume fraction of hydrogen is 10-100%, and the flow rate of the mixed gas is 10-60 mL / min; the reduction temperature is 100-300° C., and the reduction time is 10-120 min; in the inert gas, the flow rate of the gas is 15-50 mL / min.
8. Use of the aminosilica sphere-supported palladium catalyst according to any one of claims 1 to 3 as a catalyst in the selective hydrogenation reaction of acetylene.
9. The use according to claim 9, characterized in that: The acetylene selective hydrogenation reaction is carried out in a fixed bed reactor under normal pressure, the catalyst is used at a temperature of 100-200° C., the mixed raw gas flow rate is 10-60 mL / min, and the mixed raw gas composition includes: 1-3 vol. % acetylene, 10-14 vol. % hydrogen, 20-25 vol. % ethylene, and the rest is helium.