A method for preparing a carbon-nitrogen layer modified platinum / alumina composite hydrogenation catalyst
By forming a carbon-nitrogen layer on alumina microspheres to modify the platinum/alumina composite catalyst, the problem of supporting and synthesizing noble metal nanoparticles was solved, the hydrogenation activity and interfacial conductivity of the catalyst were improved, and the catalytic performance was enhanced.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-09-21
- Publication Date
- 2026-04-14
AI Technical Summary
In existing technologies, the synthesis of loaded noble metal nanoparticles faces challenges such as easy loss, aggregation, and insufficient interfacial conductivity, which affect catalytic activity.
Near-ultraviolet (UVA) light is used to reduce Pt ions to generate ultrafine Pt nanoparticles, which are then mixed with alumina microspheres and calcined in one step to form a carbon-nitrogen layer-modified platinum/alumina composite catalyst, thus solving the problems of anchoring protection and interfacial conductivity of precious metals.
The prepared catalyst exhibits excellent hydrogenation catalytic activity, effectively enhancing catalytic performance and showing broad application prospects.
Smart Images
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of hydrogenation catalytic nanomaterials technology, and specifically relates to a method for preparing a carbon-nitrogen layer modified platinum / alumina composite hydrogenation catalyst. Background Technology
[0002] In recent years, scientific progress and development have pushed the precision of chemical preparation to unprecedented heights. Hydrogenation, a common process in the biopharmaceutical and fine chemical industries, demands large quantities of catalysts and faces high technological barriers. To date, experts and scholars have explored various semiconductor materials (such as metal oxides, sulfides, and nitride oxides) as supports. Among them, alumina has attracted widespread attention due to its high mechanical strength and relatively high chemical stability. Noble metal nanoparticles are typically chosen as the active species for the support, mainly due to the strong metal-support interaction (SMSI) between the noble metal nanoparticles and the support. However, the controllable loading and synthesis of noble metal nanoparticles presents several technical challenges, including the following:
[0003] (1) In catalytic applications including heterogeneous catalysis, electrocatalysis and hydrogenation catalysis, the shear force generated by the mutual movement of the reaction system can easily lead to the loss of precious metal species due to the destructive force on the active sites. The anchoring and protection of precious metal corner sites is a major problem.
[0004] (2) The enhancement of the activity of noble metals usually relies on the nano-size effect. However, nano-sized noble metals are prone to agglomeration at high temperatures, and the anti-agglomeration and anti-sintering of noble metal nanoparticles is a major challenge.
[0005] (3) Improving the conductivity of the interface of noble metal-semiconductor heterojunction is a major challenge. How to improve the interfacial conductivity of composite catalysts while ensuring catalytic activity is an urgent problem to be solved. Summary of the Invention
[0006] To address the aforementioned problems, this invention provides a method for preparing a carbon-nitrogen layer-modified platinum / alumina composite hydrogenation catalyst. This invention uses near-ultraviolet (UVA) light (wavelength 200nm-400nm) as the photoreduction driving light source. In a layered liquid crystal template pre-dispersed uniformly with chloroplatinic acid, in-situ UV irradiation reduces Pt ions to generate ultrafine Pt nanoparticles. These nanoparticles are then mixed with alumina microspheres and subjected to a one-step calcination reduction process to reduce the remaining unreacted high-valence free Pt to elemental Pt nanoparticles. Simultaneously, the liquid crystal is converted into a carbon-nitrogen layer, yielding a carbon-nitrogen layer-modified platinum / alumina composite catalyst (CN-Pt / Al2O3).
[0007] The technical solution adopted in this invention is as follows:
[0008] A method for preparing a carbon-nitrogen layer-modified platinum / alumina composite hydrogenation catalyst includes the following steps:
[0009] (1) Dissolve chloroplatinic acid hexahydrate in deionized water, stir evenly, add camphor sulfonic acid, heat to 60°C and stir evenly, then add hexadecylpyridine chloride and continue stirring to obtain an orange transparent mixture, cool to room temperature, and then irradiate under ultraviolet light for 30 min.
[0010] (2) Disperse the mixture obtained in step (1) in ethanol, then add alumina spheres, ultrasonically disperse evenly, and dry at 100°C;
[0011] (3) The product dried in step (2) is heated and calcined in air to obtain a carbon-nitrogen layer modified platinum / alumina composite hydrogenation catalyst CN-Pt / Al2O3.
[0012] Preferably, in step (1), the amount of chloroplatinic acid hexahydrate used is 1.3 mg, 2.6 mg, 5.2 mg and 10.4 mg; the amount of deionized water used is 1.28 mL; and the power of the ultraviolet lamp is 40 W.
[0013] Preferably, the amount of camphor sulfonic acid used in step (1) is 0.23g; the molar ratio of camphor sulfonic acid to hexadecylpyridine chloride is 1:1.
[0014] Preferably, in step (2), the amount of ethanol used is 10 mL and the amount of aluminum oxide used is 500 mg.
[0015] Preferably, the heating and calcining temperature in step (3) is 550°C and the calcination time is 1 hour.
[0016] The beneficial effects of this invention are: the preparation method is simple and easy to implement, and the preparation conditions are easy to control. The prepared carbon-nitrogen layer modified platinum / alumina composite hydrogenation catalyst has good hydrogenation catalytic activity and has certain application prospects. Attached image description:
[0017] Figure 1 This is a transmission electron microscope (TEM) image of CN-Pt / Al2O3-2.6 prepared in Example 2.
[0018] Figure 2 These are photographs of the CN-Pt / Al2O3 catalysts prepared in Examples 1-4 and the Pt / Al2O3 catalyst prepared in Comparative Example 1.
[0019] Figure 3 These are Raman diagrams of the CN-Pt / Al2O3 catalysts prepared in Examples 1-4 and the Pt / Al2O3 catalyst prepared in Comparative Example 1. Detailed Implementation
[0020] Example 1
[0021] (1) Dissolve 1.3 mg of chloroplatinic acid hexahydrate in 1.28 mL of deionized water, stir for 10 min to mix evenly, then add 0.23 g of camphor sulfonic acid and stir evenly at 60 °C, then add 1.219 g of hexadecylpyridine chloride and continue stirring evenly to obtain an orange transparent mixture. Finally, cool the obtained orange transparent substance to room temperature and irradiate it under a UV lamp for 30 min.
[0022] (2) Disperse the mixture obtained in step (1) in 10 mL of ethanol, then add 500 mg of alumina microspheres, ultrasonically disperse evenly, and then dry at 100 °C.
[0023] (3) The product obtained in step (2) was calcined at 550°C for 1 hour in air atmosphere to obtain a platinum / alumina composite hydrogenation catalyst (CN-Pt / Al2O3-1.3) modified with carbon nitrogen layer and containing 1.3 mg (0.0025 mmol) of chloroplatinic acid.
[0024] The prepared catalyst was used for the hydrogenation of benzoic acid (BA) to prepare cyclohexanecarboxylic acid (CCA): the reaction temperature was 165℃, the hydrogen pressure was 1.2 MPa, the volume ratio of reactants was V(benzoic acid):V(hydrogen) = 2:1, and the catalyst packing volume was 10 cm³. 3 The reaction was carried out in a high-pressure reactor for 1 hour. The conversion rate of benzoic acid was 86%, and the selectivity was 77%.
[0025] Example 2
[0026] (1) Dissolve 2.6 mg of chloroplatinic acid hexahydrate in 1.28 mL of deionized water, stir for 10 min to mix evenly, then add 0.23 g of camphor sulfonic acid and stir evenly at 60 °C, then add 1.219 g of hexadecylpyridine chloride and continue stirring evenly to obtain an orange transparent mixture. Finally, cool the obtained orange transparent substance to room temperature and irradiate it under a UV lamp for 30 min.
[0027] (2) Disperse the mixture obtained in step (1) in 10 mL of ethanol, then add 500 mg of alumina microspheres, ultrasonically disperse evenly, and then dry at 100 °C.
[0028] (3) The product obtained in step (2) was heated to 550°C and calcined for 1 hour in air atmosphere to obtain a platinum / alumina composite hydrogenation catalyst (CN-Pt / Al2O3-2.6) modified with carbon and nitrogen layers and containing 2.6 mg (0.005 mmol) of chloroplatinic acid.
[0029] Figure 1The TEM image of the composite catalyst prepared in this embodiment shows that Pt particles were successfully supported on Al2O3 particles in the composite hydrogenation catalyst, and the formation of a carbon layer is visible.
[0030] The prepared catalyst was used for the hydrogenation and deoxygenation reaction of m-methylphenol: m-methylphenol was subjected to a reaction at 1 MPa and 250 °C, with a catalyst packing volume of 10 cm³. 3 The reaction proceeded with hydrogen for 1 hour. The conversion rate of meta-phenol was 96%, the yield of toluene was 65%, and the yield of methylcyclohexane was 33%. After the catalyst was recycled, the initial yield could be maintained at over 95%.
[0031] Example 3
[0032] (1) Dissolve 5.2 mg of chloroplatinic acid hexahydrate in 1.28 mL of deionized water, stir for 10 min to mix evenly, then add 0.23 g of camphor sulfonic acid and stir evenly at 60 °C, then add 1.219 g of hexadecylpyridine chloride and continue stirring evenly to obtain an orange transparent mixture. Finally, cool the obtained orange transparent substance to room temperature and irradiate it under a UV lamp for 30 min.
[0033] (2) Disperse the mixture obtained in step (1) in 10 mL of ethanol, then add 500 mg of alumina microspheres, ultrasonically disperse evenly, and then dry at 100 °C.
[0034] (3) The product obtained in step (2) was calcined at 550°C for 1 hour in air atmosphere to obtain a platinum / alumina composite hydrogenation catalyst (CN-Pt / Al2O3-5.2) modified with carbon nitrogen layer and containing 5.2 mg (0.01 mmol) of chloroplatinic acid.
[0035] The prepared catalyst was used in a series hydrogenation-decarboxylation reaction of fatty acids: tall oil fatty acids (TOFA) were subjected to a hydrogenation-decarboxylation reaction at 0.5 MPa and 180 °C, with a catalyst packing volume of 10 cm³. 3 The reaction was carried out for 2 hours. The conversion rate of TOFA reached 92%, and the yield of long-chain alkanes reached 85%.
[0036] Example 4
[0037] (1) Dissolve 10.4 mg of chloroplatinic acid hexahydrate in 1.28 mL of deionized water, stir for 10 min to mix evenly, then add 0.23 g of camphor sulfonic acid and stir evenly at 60 °C, then add 1.219 g of hexadecylpyridine chloride and continue stirring evenly to obtain an orange transparent mixture. Finally, cool the obtained orange transparent substance to room temperature and irradiate it under a UV lamp for 30 min.
[0038] (2) Disperse the mixture obtained in step (1) in 10 mL of ethanol, then add 500 mg of alumina microspheres, ultrasonically disperse evenly, and then dry at 100 °C.
[0039] (3) The product obtained in step (2) was heated to 550°C and calcined for 1 hour in air atmosphere to obtain a platinum / alumina composite hydrogenation catalyst (CN-Pt / Al2O3-10.4) modified with carbon and nitrogen layers and containing 10.4 mg (0.02 mmol) of chloroplatinic acid.
[0040] Comparative Example 1
[0041] (1) Dissolve 1.3 mg of chloroplatinic acid hexahydrate in 1.28 mL of deionized water, stir for 10 min to mix thoroughly, then add 0.25 g of polyethylene glycol octylphenyl ether (Triton X-100) and stir at 60 °C until homogeneous. Then add 1.58 g of n-decyl alcohol (nC 10 H 21 Continue stirring until homogeneous to obtain a colorless mixture. Finally, cool the obtained colorless mixture to room temperature and irradiate it under a UV lamp for 30 minutes.
[0042] (2) Disperse the mixture obtained in step (1) in 10 mL of ethanol, then add 500 mg of alumina microspheres, ultrasonically disperse evenly, and then dry at 100 °C.
[0043] (3) The product obtained in step (2) is heated to 550°C and calcined for 1 hour in air atmosphere to obtain platinum / alumina composite catalyst (Pt / Al2O3).
[0044] Figure 3 Raman spectra of the CN-Pt / Al2O3 catalysts prepared in Examples 1-4 and the Pt / Al2O3 catalyst prepared in Comparative Example 1 are shown. Compared with pure Al2O3, the Raman band of Eg is significantly broadened and its intensity decreases. Furthermore, at 143.1 cm⁻¹... -1 The red shift of the Eg peak at the location is related to the strong interaction (SMSI) between the support and the noble metal during calcination. The higher the content, the more obvious the red shift phenomenon caused by the SMSI interaction during calcination.
Claims
1. A method for preparing a carbon-nitrogen layer-modified platinum / alumina composite hydrogenation catalyst, characterized in that, Includes the following steps: (1) Dissolve chloroplatinic acid hexahydrate in deionized water, stir evenly, add camphor sulfonic acid, heat to 60°C and stir evenly, then add hexadecylpyridine chloride and continue stirring to obtain an orange transparent mixture, cool to room temperature, and then irradiate the mixture under a UV lamp for 30 min. (2) Disperse the mixture obtained in step (1) in ethanol, then add alumina beads, ultrasonically disperse evenly, and dry at 100°C; (3) The product dried in step (2) is heated and calcined in air to obtain a carbon-nitrogen layer modified platinum / alumina composite hydrogenation catalyst CN-Pt / Al2O3; the amount of camphor sulfonic acid used in step (1) is 0.23g; the molar ratio of camphor sulfonic acid to hexadecylpyridine chloride is 1:
1.
2. The method for preparing the carbon-nitrogen layer-modified platinum / alumina composite hydrogenation catalyst according to claim 1, characterized in that, In step (1), the dosage of chloroplatinic acid hexahydrate is 1.3 mg, 2.6 mg, 5.2 mg and 10.4 mg; the dosage of deionized water is 1.28 mL; and the power of the ultraviolet lamp is 40 W.
3. The method for preparing the carbon-nitrogen layer-modified platinum / alumina composite hydrogenation catalyst according to claim 1, characterized in that, In step (2), the amount of ethanol used is 10 mL; the amount of aluminum oxide used is 500 mg.
4. The method for preparing the carbon-nitrogen layer-modified platinum / alumina composite hydrogenation catalyst according to claim 1, characterized in that, In step (3), the heating and calcination temperature is 550℃ and the calcination time is 1h.