CN114471724A - Au-Pd NPs @ NMOF-Ni ultrathin nanosheet composite material and preparation method and application thereof - Google Patents

Au-Pd NPs @ NMOF-Ni ultrathin nanosheet composite material and preparation method and application thereof Download PDF

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CN114471724A
CN114471724A CN202210050198.9A CN202210050198A CN114471724A CN 114471724 A CN114471724 A CN 114471724A CN 202210050198 A CN202210050198 A CN 202210050198A CN 114471724 A CN114471724 A CN 114471724A
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nps
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CN114471724B (en
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温丽丽
郭套连
莫凯丽
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Central China Normal University
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    • B01J31/00—Catalysts comprising hydrides, coordination complexes or organic compounds
    • B01J31/16—Catalysts comprising hydrides, coordination complexes or organic compounds containing coordination complexes
    • B01J31/1691—Coordination polymers, e.g. metal-organic frameworks [MOF]
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
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    • C07C45/00—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds
    • C07C45/27—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by oxidation
    • C07C45/32—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by oxidation with molecular oxygen
    • C07C45/37—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by oxidation with molecular oxygen of >C—O—functional groups to >C=O groups
    • C07C45/38—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by oxidation with molecular oxygen of >C—O—functional groups to >C=O groups being a primary hydroxyl group
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Abstract

The invention provides an Au-Pd NPs @ NMOF-Ni ultrathin nanosheet composite material as well as a preparation method and application thereof, belonging to the technical field of organic catalysis and comprising the following steps: s1, mixing 5,4-PMIA, TPOM, PVP and Ni (CH)3COO)2·4H2Adding O into a solvent, heating, cooling, washing and drying to obtain NMOF-Ni; s2, adding NDispersing MOF-Ni in water, adding HAuCl4·6H2O and PdCl2Stirring, centrifuging, washing, re-dispersing in water, adding NaBH4Stirring, centrifuging, washing and drying to obtain AuxPdy@ NMOF-Ni ultrathin nanosheet composite material. Au prepared by the inventionxPdyThe @ NMOF-Ni composite material is used for catalyzing the oxidation reaction of benzyl alcohol, and can realize the conversion into benzaldehyde with high efficiency and high selectivity under the conditions of no alkali and normal pressure.

Description

Au-Pd NPs @ NMOF-Ni ultrathin nanosheet composite material and preparation method and application thereof
Technical Field
The invention relates to the technical field of organic catalysis, in particular to an Au-Pd NPs @ NMOF-Ni ultrathin nanosheet composite material and a preparation method and application thereof.
Background
The selective oxidation of alcohols to aldehydes or ketones is an important class of organic synthesis reactions. In recent years, Metal Nanoparticles (MNPs) have attracted much attention because they exhibit high catalytic activity in catalyzing the oxidation of benzyl alcohol. However, MNPs are extremely easy to agglomerate in the catalytic process, so that the activity is reduced, the recovery is difficult, and the requirements of green chemical sustainable development are not met. The MNPs are loaded in the porous material, so that the catalytic activity and the recycling property can be effectively improved. The Au and Pd nanoparticles, especially the Au-Pd bimetallic nanoparticle composite material show excellent catalytic performance in the process of catalyzing the benzyl alcohol oxidation reaction. However, most catalytic reactions generally require the performance of large amounts of base and high pressure, and are accompanied by the formation of benzoic acid and methyl benzoate as by-products. Therefore, the development of heterogeneous catalysts that can efficiently catalyze the oxidation of alcohols to aldehydes under mild reaction conditions without alkali has been the subject of research by researchers.
Disclosure of Invention
The invention aims to provide an Au-Pd NPs @ NMOF-Ni ultrathin nanosheet composite material, a preparation method and application thereof, and prepared AuxPdyThe @ NMOF-Ni composite material is applied to catalyzing the oxidation reaction of benzyl alcohol, and can realize the high-efficiency and high-selectivity conversion into benzaldehyde under the conditions of no alkali and normal pressure.
The technical scheme of the invention is realized as follows:
the invention provides a preparation method of an Au-Pd NPs @ NMOF-Ni ultrathin nanosheet composite material, which comprises the following steps:
s1. preparation of NMOF-Ni:
mixing 5,4-PMIA, TPOM, PVP and Ni (CH)3COO)2·4H2Adding O into a solvent, stirring at room temperature for 5-15min, heating to 140-160 ℃, continuously reacting for 20-40min, cooling to room temperature, washing, and drying to obtain NMOF-Ni;
S2.AuxPdypreparation of @ NMOF-Ni:
introduction of NMOF-Ni was uniformly dispersed in water and HAuCl was added with stirring4·6H2O and PdCl2Stirring at room temperature for 20-40min, centrifuging, washing, dispersing in water, adding NaBH4Continuously stirring the aqueous solution for 20-40min, centrifuging, washing and drying to obtain AuxPdy@ NMOF-Ni ultrathin nanosheet composite material.
As a further improvement of the present invention, the 5,4-PMIA, TPOM, polyvinylpyrrolidone and Ni (CH) are added in step S13COO)2·4H2The mass ratio of O is 1: (0.5-1.5): (3-7): (0.5-1.5).
As a further improvement of the invention, the solvent in step S1 is at least one selected from N, N-dimethylformamide and XX.
As a further improvement of the invention, the HAuCl is provided in step S24·6H2O and PdCl2The ratio of the amounts of the substances (1-3): (1-2).
As a further improvement of the invention, the HAuCl is provided in step S24·6H2O and PdCl2The ratio of the amounts of the substances of (a) to (b) is 2: 1.
As a further improvement of the invention, the NMOF-Ni, HAuCl are described in step S24·6H2O and PdCl2Total mass of, NaBH4The mass ratio of (A) to (B) is 15: (0.5-1): (1-2).
The invention further provides the Au-Pd NPs @ NMOF-Ni ultrathin nanosheet composite material prepared by the preparation method.
As a further improvement of the invention, the Au content in the material is 1-4 wt%, and the Pd content is 0.5-2 wt%.
As a further improvement of the invention, the ratio of the amounts of the substances Au and Pd in the material is (10-27): (10-27).
The invention further protects the application of the Au-Pd NPs @ NMOF-Ni ultrathin nanosheet composite material in catalytic organic reaction.
The invention has the following beneficial effects: the invention prepares AuxPdy@ NMOF-Ni composite material and its applicationIn the catalytic benzyl alcohol oxidation reaction, the high-efficiency and high-selectivity conversion into benzaldehyde can be realized under the conditions of no alkali and normal pressure. Under the same reaction condition, compared with Au @ NMOF-Ni and Pd @ NMOF-Ni loaded with single metal nanoparticles, the catalytic performance of AuxPdy @ NMOF-Ni loaded with double metal nanoparticles is obviously enhanced. When the molar ratio of Au to Pd is 2:1, the catalytic performance of the composite material (Au2Pd1@ NMOF-Ni) is optimal, and the catalytic performance is not obviously changed after 5 times of recycling. In addition, the present inventors have found Au2Pd1In @ NMOF-Ni may influence Au2Pd1Electronic character of NPs surface, formation of Au2Pd1Anionic species of NPs; synergistic effect between Au-Pd is more effective in removing O2Activated into a peroxide state species, thereby promoting the conversion of the benzyl alcohol into benzaldehyde.
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In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
FIG. 1 shows NMOF-Ni, Au @ NMOF-Ni, Pd @ NMOF-Ni and AuxPdyPXRD pattern of @ NMOF-Ni;
FIG. 2 shows NMOF-Ni and Au2Pd1SEM image of @ NMOF-Ni and Au2Pd1SEM-EDS elemental profile of @ NMOF-Ni;
FIG. 3 is Au2Pd1TEM and HAADF-STEM of @ NMOF-Ni, and Au2Pd1NPs particle size distribution profile;
FIG. 4 shows NMOF-Ni and Au2Pd1The nitrogen adsorption isotherm and the pore size distribution diagram of @ NMOF-Ni at 77K;
FIG. 5 is Au2Pd1XPS spectra for @ NMOF-Ni;
FIG. 6 is AuxPdyA comparison graph of the oxidation performance of the @ NMOF-Ni catalytic benzyl alcohol;
FIG. 7 is Au2Pd1@ NMOF-Ni and bulk Au2Pd1Comparison of experiment for catalyzing benzyl alcohol oxidation cycle by using @ MOF-Ni and Au2Pd1PXRD patterns before and after @ NMOF-Ni cycle;
FIG. 8 is Au2Pd1TEM image after @ NMOF-Ni cycle and Au after cycle2Pd1Particle size distribution profile of NPs;
FIG. 9 is Au2Pd1A possible reaction mechanism diagram of the catalyst benzyl alcohol oxidation of @ NMOF-Ni.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Chloroauric acid (HAuCl)4·3H2O, 98%, alatin), palladium chloride (PdCl)298%, Leyan, benzyl alcohol (98%, Chinese medicine), 4-methylbenzyl alcohol (98%, Bi De), 4-methoxybenzyl alcohol (98%, Bi De), 4-fluorobenzyl alcohol (97%, Bi De), 4-chlorobenzyl alcohol (99.54%, Bi De), the above medicines were purchased and used directly, and other experimental medicines were as in the previous section.
TG 16-II type high speed centrifuge, magnetic stirrer, USB2000+ ultraviolet-visible absorption spectrometer, Ultra 55 scanning electron microscope, NTEGRA/NT-MDT atomic mechanics microscope, Quantachrome IQ2Specific surface area analyzer, FEI Tecnai G2F 20 transmission electron microscope, Samdri-PVT-3D supercritical carbon dioxide dryer, Siemens D5005X-ray powder diffractometer (Cu/Ka), K-Alpha type X-ray photoelectron spectroscopy, Thermo-TRACE-1300 gas chromatograph (FID detector).
Example 1
The embodiment provides a preparation method of an Au-Pd NPs @ NMOF-Ni ultrathin nanosheet composite material, which comprises the following steps:
s1. preparation of NMOF-Ni
5,4-PMIA (0.1g,0.37mmol), TPOM (0.1g,0.22mmol), PVP (0.5g) and Ni (CH)3COO)2·4H2O (0.1g,0.4mmol) was added to 10mL DMF, stirred at room temperature for 10min and then heated to 150 ℃ for 30 min. Finally, cooling to room temperature, washing with centrifugal ethanol for three times, and drying at 60 ℃ to obtain NMOF-Ni;
S2.Au1Pd1preparation of @ NMOF-Ni:
0.15g of NMOF-Ni was uniformly dispersed in 20mL of deionized water, and 300. mu.L of HAuCl was added with stirring4·6H2O (0.047M) in water and 300. mu.L of PdCl2(0.047M) in water, stirring was continued at room temperature for 30min, washed 3 times with deionized water and redispersed in 20mL of deionized water. Subsequently, 3mL of NaBH was added to the above dispersion4(0.1M) aqueous solution, stirring was continued for 30 min. Finally centrifuging, washing with deionized water for three times, and vacuum drying to obtain Au1Pd1@NMOF-Ni。
Example 2
In step S2, 400. mu.L of HAuCl was added as compared with example 14·6H2O (0.047M) in water and 200. mu.L of PdCl2(0.047M) under otherwise unchanged conditions to give Au2Pd1@NMOF-Ni。
Example 3
In step S2, 450. mu.L of HAuCl was added as compared with example 14·6H2O (0.047M) in water and 150. mu.L of PdCl2(0.047M) under otherwise unchanged conditions to give Au3Pd1@NMOF-Ni。
Example 4
In step S2, 200. mu.L of HAuCl was added as compared with example 14·6H2O (0.047M) in water and 300. mu.L of PdCl2(0.047M) under otherwise unchanged conditions to give Au1Pd2@NMOF-Ni。
Comparative example 1
In step S2, 600. mu.L of HAuCl was added as compared with example 14·6H2And O (0.047M) aqueous solution, and the other conditions are not changed to obtain Au @ NMOF-Ni.
Comparative example 2
In step S2, 600. mu.L of PdCl was added, compared to example 12(0.047M) in water, and the other conditions were not changed to obtain Pd @ NMOF-Ni.
Comparative example 3
Compared with the example 1, the NMOF-Ni in the step S1 is replaced by the MOF-Ni, other conditions are not changed, and Au is prepared2Pd1@MOF-Ni。
In the presence of 5,4-PMIA (6.9mg,0.025mmol), TPOM (11.1mg,0.025mmol) and Ni (NO)3)2·6H2To a mixture of O (7.3mg,0.025mmol) was added 1 drop HCl (2M), 2mL DMA and 1mL H2O and stirred well. And then, transferring the mixture to a 25mL reaction kettle, standing for 72h at 140 ℃, naturally cooling to room temperature, washing and drying to obtain the MOF-Ni.
Test example 1
The powder materials obtained in examples 1 to 4 and comparative examples 1 to 2 were subjected to X-ray diffraction (PXRD), and the results are shown in FIG. 1. As can be seen from the figure, the crystal structure of NMOF-Ni did not change significantly after loading NPs. In addition, no Au NPs, Pd NPs and Au were observed in the PXRD spectrumxPdyCharacteristic diffraction peaks of NPs, which may be due to the low content of MNPs and too small particle size.
Test example 2
The contents of Au and Pd elements in the composite materials were measured by inductively coupled plasma atomic emission spectrometry (ICP-AES) using the powders of the materials obtained in examples 1 to 4 and comparative examples 1 to 2, and the results are shown in Table 1.
TABLE 1
Figure BDA0003473612140000071
As can be seen from the above table, the total molar content of (Au + Pd) in all samples is very similar, i.e., the content of MNPs per 100mg of the composite material is about 0.017mmol (Table 1). In addition, composite Au3Pd1@NMOF-Ni、Au2Pd1@NMOF-Ni、Au1Pd1@ NMOF-Ni and Au1Pd2The molar ratio of the Au element to the Pd element contained in @ NMOF-Ni is 26: 11. 17 of the formula: 10. 49: 50 and 11: 25, in close proximity to the molar ratios of Au and Pd we initially added, 3:1, 2:1, 1:1 and 1: 2.
Test example 3
The material powders obtained in examples 1 to 4 and comparative examples 1 to 2 were subjected to Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM) analyses, and the results are shown in fig. 2 and 3.
FIG. 2, wherein (a) is an SEM image of NMOF-Ni; (b) is Au2Pd1SEM picture of @ NMOF-Ni; (c) is Au2Pd1SEM-EDS elemental profile of @ NMOF-Ni. NMOF-Ni and Au2Pd1Scanning Electron Microscope (SEM) characterization of @ NMOF-Ni shows that Au is loaded2Pd1Au behind nanoparticles2Pd1The @ NMOF-Ni and the non-loaded NMOF-Ni both present similar nanoflake-composed nanoflower-like structures (FIGS. 2a and 2b), which indicates that the original microstructure is not destroyed after the material is compounded. Au coating2Pd1SEM-EDS elemental distribution of @ NMOF-Ni showed that both Au and Pd elements exhibited a uniform spatial distribution (FIG. 2c), indicating that Au2Pd1The NPs are uniformly dispersed throughout the composite matrix.
As shown in FIG. 3, in which (a) and (b) are Au2Pd1TEM image of @ NMOF-Ni, (c) HAADF-STEM image, and (d) Au2Pd1@ NMOF-Ni in Au2Pd1NPs particle size distribution plot. Au coating2Pd1The characterization results of @ NMOF-Ni Transmission Electron Microscope (TEM) (FIGS. 3a and 3b) and high-Angle annular dark-field scanning Transmission Electron microscope (HAADF-STEM) (FIG. 3c) show Au2Pd1NPs were highly uniformly dispersed throughout the NMOF-Ni nanoplates with an average particle size of 1.17nm (fig. 3 d).
Test example 4
Powders of the materials obtained in examples 1 to 4 and comparative examples 1 to 2 were mixed in N2The results of the physical adsorption test at 77K are shown in FIG. 4.
FIG. 4, wherein (a) is NMOF-Ni and Au2Pd1The nitrogen adsorption isotherm at 77K for @ NMOF-Ni; (b) is NMOF-Ni and Au2Pd1@ NMOF-Ni pore size distribution plot. NMOF-Ni and Au2Pd1@ NMOF-Ni all exhibit the type I curve of the typical microporous structure. Au coating2Pd1Specific surface area and pore volume of @ NMOF-Ni 762m from NMOF-Ni2 g-1And 0.631cm3 g-1Respectively reduced to 328.8m2 g-1And 0.455cm3 g-1. The significant reduction in specific surface area and pore capacity may be attributed to Au2Pd1NPs are distributed in the interior of NMOF-Ni and occupy a part of the pores. In addition, as can be seen from the pore size distribution pattern in Au2Pd1In @ NMOF-Ni, the microporous structure still occupies the major part, illustrating that Au is loaded2Pd1After NPs, Au2Pd1@ NMOF-Ni still keeps the microporous structure unchanged.
Test example 5
The powder materials obtained in examples 1 to 4 and comparative examples 1 to 2 were subjected to X-ray photoelectron spectroscopy (XPS) analysis, and the results are shown in FIG. 5.
As shown in FIG. 5, as shown in FIG. 5a, Au2Pd1Peaks for C1 s, N1 s, O1 s, Ni 2p, Pd 3d, and Au 4f appeared in the @ NMOF-Ni sample. XPS spectrum of Ni 2p with peaks at 855.4 and 873.0eV of Ni2+2p of3/2And 2p1/2And (4) a peak indicating that the valence state of the Ni element is unchanged before and after the recombination. The XPS spectrum of Au 4f has two obvious peaks at 83.2 eV and 86.9 eV, which belong to metal Au 04f of7/2And 4f5/2(FIG. 5 c). With Au in Au @ NMOF-Ni0Binding energy of 4f (Au)0 4f7/2:83.8eV；Au 04f5/287.5 eV), Au2Pd1@ NMOF-Ni in Au0The peak of 4f is shifted to the low binding energy direction. XPS spectrum of Pd 3d, two peaks at 340.6 and 335.0 eV are attributed to metallic Pd 03d of3/2And 3d5/2(FIG. 5 d). Likewise, compared to Pd in Pd @ NMOF-Ni0Binding energy of 3d (Pd)0 3d3/2:341.1eV；Pd 0 3d5/2:335.7 eV)，Au2Pd1@ NMOF-Ni Pd in Ni0The peak of 3d is shifted to the low binding energy direction. Bimetallic Au2Pd1Au in NPs 04f and Pd0Shift in binding energy of 3d, indicating Au2Pd1A synergistic effect exists between Au and Pd in @ NMOF-Ni. Notably, the two peaks at 342.9 eV and 337.5 eV in the XPS spectrum of Pd 3d are assigned to Pd 2+3d of3/2And 3d5/2Showing that of Au2Pd1In NPs, the surface of Pd is partially oxidized, Pd2+The proportion of (B) was 7.8%. Compared with Pd in Pd @ NMOF-Ni2+Proportion of (3%), Au2Pd1@ NMOF-Ni Pd in Ni0Is greatly reduced. This is probably because of Au2Pd1Au and Pd atoms in @ NMOF-Ni are arranged at intervals, so that Au can be effectively prevented2Pd1The Pd atoms in the NPs are oxidized.
Test example 6 test of catalytic Performance
The process of the benzyl alcohol oxidation reaction: 0.5mmol of benzyl alcohol, 2mL of toluene, and 10mg of the powdery catalyst obtained in examples 1-4 and comparative examples 1-2 were charged in a 10mL reaction flask and uniformly dispersed by sonication. Connecting the reaction bottle with a reflux condenser tube, vacuumizing for 5min, inserting an oxygen balloon, pre-adsorbing for 0.5h, and reacting for 9h at 120 ℃ under ice water reflux. After the reaction, chlorobenzene (30. mu.L) was added as an internal standard for gas chromatography, and after centrifugation, the supernatant was collected for gas analysis to determine the conversion.
The results are shown in FIG. 6.
As shown in FIG. 6, Au supporting bimetallic nanoparticles was compared with Au @ NMOF-Ni and Pd @ NMOF-Ni supporting single metal nanoparticles under the same reaction conditionsxPdyThe catalytic performance of @ NMOF-Ni is significantly enhanced. The result shows that the molar ratio of Au to Pd is 2:1, and Au is the optimal ratio2Pd1The @ NMOF-Ni has the highest catalytic activity, the conversion rate is 99 percent after the reaction is carried out for 9 hours, and the TOF reaches 30.7 hours-1。
Au prepared in the embodiment 2 of the invention2Pd1The @ NMOF-Ni catalyst was replaced with other catalysts, and the catalytic efficiency under different reaction conditions is shown in Table 2.
TABLE 2
Figure BDA0003473612140000101
Figure BDA0003473612140000111
As can be seen from the above table, Au obtained in example 2 of the present invention2Pd1The catalytic performance of the @ NMOF-Ni catalyst is higher than that of most reported MNPs/MOFs composite materials. The above results indicate that there is a clear synergistic effect between Au and Pd.
Fixing the material powder catalyst to Au obtained in example 22Pd1@ NMOF-Ni, substituting benzyl alcohol with other different starting materials, the conversion results are shown in Table 3.
TABLE 3
Figure BDA0003473612140000112
In consideration of the above experimental results, we consider Au with the best catalytic performance2Pd1The @ NMOF-Ni composite material is a research target, and the research results are shown in Table 3 for a benzyl alcohol derivative substrate containing different substituents. When the substituent group of the benzyl alcohol is an electron donating group (such as 4-methoxy benzyl alcohol and 4-methyl benzyl alcohol), the conversion rate is higher and reaches 99 percent. When the substituents were electron withdrawing groups (4-fluorobenzyl alcohol and 4-chlorobenzyl alcohol), the conversion was relatively low, 34.6% and 15.9%, respectively. This is probably because the electron cloud density of the benzene ring increases with the increase in the electron donating ability of the substituent, so that the aromatic alcohol is more easily oxidized into the aromatic aldehyde. It is noted that in all the oxidation reactions of benzyl alcohol derivatives, the products are corresponding benzaldehyde derivatives, and excellent selectivity is shown. This result indicates that the catalytic system has good substrate applicability.
Test example 7 catalytic cycle test
Au obtained in example 22Pd1@ NMOF-Ni and Au obtained in comparative example 32Pd1The results of the catalytic cycling experiment carried out with @ MOF-Ni are shown in the figure7、8。
In FIG. 7, (a) is Au2Pd1@ NMOF-Ni and bulk Au2Pd1Experimental comparison of catalytic benzyl alcohol oxidation cycles of @ MOF-Ni; (b) is Au2Pd1PXRD patterns before and after @ NMOF-Ni cycle; compared with Au2Pd1@ NMOF-Ni nanocomposite, bulk Au2Pd1The catalytic activity of @ MOF-Ni was relatively low, with a conversion of benzyl alcohol of 83.2% under the same reaction conditions. For Au2Pd1The experimental tests of catalytic cycling with @ NMOF-Ni revealed no significant decrease in catalytic performance after 5 cycles (FIG. 7 a). And Au in bulk phase2Pd1The cyclability of @ MOF-Ni is relatively poor. In FIG. 8, (a) is Au2Pd1TEM image after @ NMOF-Ni cycle; (b) is Au after circulation2Pd1Particle size distribution of NPs, Au after circulation2Pd1TEM image and particle size distribution diagram of @ NMOF-Ni show Au2Pd1The NPs still exhibit a uniform distribution. The results show that the MOFs ultrathin nanosheets can better disperse MNPs, so that the catalytic activity and stability of the catalyst are further improved.
Based on the above results, for Au2Pd1The reaction mechanism of the reaction is proposed by the catalytic oxidation of benzyl alcohol to benzaldehyde under the condition of @ NMOF-Ni, and is shown in figure 9. Au coating2Pd1In the @ NMOF-Ni composite material NMOF-Ni may affect Au2Pd1Electronic character of NPs surface, formation of Au in anionic form2Pd1NPs, which more readily activate O2. Thus, O2Possibly in the form of peroxide, is adsorbed on its surface (Step 1). Subsequently, the benzyl alcohol is adsorbed on O2 δ-Nearby Au2Pd1NPs (Step 2). Finally, the benzyl alcohol undergoes the elimination of beta-H to form the corresponding benzaldehyde accompanied by O2And H2O is generated (Step 3). At the same time, the catalyst returns to the original metallic state.
The invention prepares Au @ NMOF-Ni and Pd @ NMOF-Ni loaded with single metal nanoparticles and Au containing bimetallic nanoparticles with different Au and Pd molar ratiosxPdy@NMOF-Ni composite material, and its application in catalyzing benzyl alcohol selective oxidation reaction. Compared with Au @ NMOF-Ni and Pd @ NMOF-Ni under the reaction conditions of no alkali and normal pressurexPdy@ NMOF-Ni showed higher catalytic activity and product selectivity. Wherein Au is2Pd1@ NMOF-Ni has the best catalytic activity (TOF of 30.7 h)-1) And excellent recyclability and good applicability to the development of substrates. The possible mechanism is: (1) au coating2Pd1In @ NMOF-Ni may influence Au2Pd1Electronic character of NPs surface, formation of Au2Pd1Anionic species of NPs; (2) the synergistic effect between Au-Pd enables the Au-Pd to more effectively activate O2Becoming a peroxidized species. Therefore, Au is present under the condition of no alkali and normal pressure2Pd1@ NMOF-Ni showed excellent catalytic oxidation properties of benzyl alcohol. This work points to a new direction for designing efficient, mild benzyl alcohol oxidation catalysts.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.

Claims (10)

1. A preparation method of an Au-Pd NPs @ NMOF-Ni ultrathin nanosheet composite material is characterized by comprising the following steps:
s1. preparation of NMOF-Ni:
mixing 5,4-PMIA, TPOM, PVP and Ni (CH)3COO)2·4H2Adding O into a solvent, stirring at room temperature for 5-15min, heating to 140-160 ℃, continuously reacting for 20-40min, cooling to room temperature, washing, and drying to obtain NMOF-Ni;
S2.AuxPdypreparation of @ NMOF-Ni:
dispersing NMOF-Ni in water uniformly, adding HAuCl under stirring4·6H2O and PdCl2Stirring at room temperature for 20-40min, centrifuging, washing, dispersing in water, adding NaBH4Dissolving in waterContinuously stirring the solution for 20-40min, centrifuging, washing and drying to obtain AuxPdy@ NMOF-Ni ultrathin nanosheet composite material.
2. The method of claim 1, wherein the 5,4-PMIA, TPOM, polyvinylpyrrolidone and Ni (CH) are mixed in step S13COO)2·4H2The mass ratio of O is 1: (0.5-1.5): (3-7): (0.5-1.5).
3. The method according to claim 1, wherein the solvent in step S1 is at least one selected from the group consisting of N, N-dimethylformamide and XX.
4. The method according to claim 1, wherein the HAuCl is in step S24·6H2O and PdCl2The ratio of the amounts of the substances (1-3): (1-2).
5. The method according to claim 4, wherein the HAuCl is contained in step S24·6H2O and PdCl2The ratio of the amounts of the substances of (a) to (b) is 2: 1.
6. The method according to claim 1, wherein the NMOF-Ni, HAuCl are performed in step S24·6H2O and PdCl2Total mass of NaBH4The mass ratio of (A) to (B) is 15: (0.5-1): (1-2).
7. An Au-Pd NPs @ NMOF-Ni ultrathin nanosheet composite prepared by the preparation method of any one of claims 1-6.
8. The Au-Pd NPs @ NMOF-Ni ultrathin nanosheet composite of claim 7, wherein the Au content in the material is 1-4 wt% and the Pd content is 0.5-2 wt%.
9. The Au-Pd NPs @ NMOF-Ni ultrathin nanosheet composite of claim 7, wherein the ratio of the amounts of Au and Pd species in the material is (10-27): (10-27).
10. Use of the Au-Pd NPs @ NMOF-Ni ultrathin nanosheet composite of any one of claims 7-9 in catalyzing an organic reaction.
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WO2014046107A1 (en) * 2012-09-20 2014-03-27 国立大学法人京都大学 Metal nanoparticle complex and method for producing same
WO2017218065A1 (en) * 2016-06-17 2017-12-21 Battelle Memorial Institute System and process for continuous and controlled production of metal-organic frameworks and metal-organic framework composites
CN107497488A (en) * 2017-09-11 2017-12-22 大连理工大学 A kind of preparation method and application of the monatomic alloy catalysts of high hydrogenation selectivity Au Pd
CN111359670A (en) * 2020-03-10 2020-07-03 浙江工业大学 Au-Pd/NH2-MIL-101(Cr) catalyst and preparation and application thereof

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2014046107A1 (en) * 2012-09-20 2014-03-27 国立大学法人京都大学 Metal nanoparticle complex and method for producing same
WO2017218065A1 (en) * 2016-06-17 2017-12-21 Battelle Memorial Institute System and process for continuous and controlled production of metal-organic frameworks and metal-organic framework composites
CN107497488A (en) * 2017-09-11 2017-12-22 大连理工大学 A kind of preparation method and application of the monatomic alloy catalysts of high hydrogenation selectivity Au Pd
CN111359670A (en) * 2020-03-10 2020-07-03 浙江工业大学 Au-Pd/NH2-MIL-101(Cr) catalyst and preparation and application thereof

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