A bimetal-based metal organic framework Pd 0.2 Ni 0.8 @MIL-101 pickering emulsion and preparation method and application thereof

Abstract

The application relates to the technical field of catalysts and relates to a metal organic framework Pd 0.2 Ni 0.8 @MIL-101 pickering emulsion and a preparation method and application thereof. The application adopts water and toluene as solvents at the same time, uses Pd 0.2 Ni 0.8 @MIL-101 as an emulsifier to form Pd 0.2 Ni 0.8 @MIL-101 pickering emulsion, the emulsifier uses low-cost metal Ni to partially replace Pd, and due to the synergistic effect between Pd and Ni, the catalytic efficiency is greatly improved, and the cost is reduced. The Pd 0.2 Ni 0.8 @MIL-101 emulsifier has simple preparation method and exhibits super-high catalytic capacity in a reductive amination series reaction of nitrobenzene.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of catalysts, and relates to a metal organic framework Pd 0.2 Ni 0.8 The application relates to a MIL-101 stabilized Pickering emulsion and a preparation method and application thereof, in particular to a preparation of a metal organic framework material stabilized Pickering emulsion for catalyzing a nitrobenzene reductive amination tandem reaction and application thereof. BACKGROUND

[0002] Metal organic framework (MOF) is a kind of crystal with a three-dimensional network structure, which is self-assembled by metal ions or metal clusters as nodes and nitrogen or oxygen polydentate organic ligands of aromatic acid or base as bridging. The crystalline porous structure of MOF can limit the migration and aggregation of metal nanoparticles. The bimetallic NP@MOF material has better catalytic activity than its single metal counterpart. The multifunctional catalyst of the bimetallic NP@MOF with three active sites (acid-metal A-metal B) not only utilizes the catalytic synergy of the bimetallic nanoparticles, but also utilizes the catalytic activity of the MOF itself.

[0003] Pickering emulsion is a kind of emulsion obtained by using superfine solid particles as emulsifiers. The solid particles are self-assembled on the interface of two immiscible liquids, can prevent the coalescence of droplets, form a large number of water or oil microdroplets, and greatly expand the interface area of water and oil. Compared with traditional emulsion, the Pickering emulsion has the advantages of low toxicity and strong stability. The Pickering interfacial catalysis has a wide application prospect in acid-catalyzed ester exchange, oxidation and acetalization reactions.

[0004] Tandem reaction is a kind of efficient, energy-saving and environmentally friendly chemical synthesis method, which is more and more attractive to the majority of chemical researchers. Tandem reaction usually refers to two or more consecutive reactions without separation of intermediate products, directly synthesizing the final product, which can effectively reduce the emission of pollutants. In the field of organic catalysis, tandem reaction has become a very potential development direction. Amines are valuable compounds, which have been widely used in dyes, rubber materials, agricultural chemicals, drugs, surfactants and the like. Direct reductive amination is one of the most convenient and widely used methods for amine synthesis, and one of the most economical and cleanest ways is to use nitroarenes instead of amines to directly reductive aminate aldehydes and ketones. SUMMARY

[0005] The purpose of the present application is to provide a Pd 0.2 N i0.8 @MIL-101 stabilized Pickering emulsion to efficiently catalyze the reductive amination tandem reaction of nitrobenzene.

[0006] The technical scheme adopted by the present application is: a metal organic framework Pd 0.2 Ni 0.8 The MIL-101 emulsifier is prepared as follows: MIL-101 is dispersed in n-hexane, and a methanol solution of sodium chloropalladate and nickel chloride is added dropwise under ultrasonic and stirring, and the mixture is uniformly dispersed by ultrasonic and stirring, and then centrifuged and dried; sodium borohydride is added to methanol, and hydrogen is released from the sodium borohydride and the methanol, and the liquid with bubbles on the upper layer is quickly taken and added to the MIL-101, the sodium chloropalladate and the nickel chloride, and stirring is continued for 30 min, and then the mixture is washed with methanol and vacuum dried to obtain Pd 0.2 Ni 0.8 The MIL-101 emulsifier is prepared as follows: MIL-101 is dispersed in n-hexane, and a methanol solution of sodium chloropalladate and nickel chloride is added dropwise under ultrasonic and stirring, and the mixture is uniformly dispersed by ultrasonic and stirring, and then centrifuged and dried; sodium borohydride is added to methanol, and hydrogen is released from the sodium borohydride and the methanol, and the liquid with bubbles on the upper layer is quickly taken and added to the MIL-101, the sodium chloropalladate and the nickel chloride, and stirring is continued for 30 min, and then the mixture is washed with methanol and vacuum dried to obtain Pd

[0007] The technical scheme adopted by the present application is: a metal organic framework Pd 0.2 N i0.8 The MIL-101 emulsifier is prepared as follows: MIL-101 is dispersed in n-hexane, and a methanol solution of sodium chloropalladate and nickel chloride is added dropwise under ultrasonic and stirring, and the mixture is uniformly dispersed by ultrasonic and stirring, and then centrifuged and dried; sodium borohydride is added to methanol, and hydrogen is released from the sodium borohydride and the methanol, and the liquid with bubbles on the upper layer is quickly taken and added to the MIL-101, the sodium chloropalladate and the nickel chloride, and stirring is continued for 30 min, and then the mixture is washed with methanol and vacuum dried to obtain Pd

[0008] The technical scheme adopted by the present application is: a metal organic framework Pd 0.2 N i0.8 The MIL-101 emulsifier is prepared as follows: MIL-101 is dispersed in n-hexane, and a methanol solution of sodium chloropalladate and nickel chloride is added dropwise under ultrasonic and stirring, and the mixture is uniformly dispersed by ultrasonic and stirring, and then centrifuged and dried; sodium borohydride is added to methanol, and hydrogen is released from the sodium borohydride and the methanol, and the liquid with bubbles on the upper layer is quickly taken and added to the MIL-101, the sodium chloropalladate and the nickel chloride, and stirring is continued for 30 min, and then the mixture is washed with methanol and vacuum dried to obtain Pd

[0009] The technical scheme adopted by the present application is: a metal organic framework Pd 0.2 N i0.8 The MIL-101 emulsifier is prepared as follows: MIL-101 is dispersed in n-hexane, and a methanol solution of sodium chloropalladate and nickel chloride is added dropwise under ultrasonic and stirring, and the mixture is uniformly dispersed by ultrasonic and stirring, and then centrifuged and dried; sodium borohydride is added to methanol, and hydrogen is released from the sodium borohydride and the methanol, and the liquid with bubbles on the upper layer is quickly taken and added to the MIL-101, the sodium chloropalladate and the nickel chloride, and stirring is continued for 30 min, and then the mixture is washed with methanol and vacuum dried to obtain Pd

[0010] The technical scheme adopted by the present application is: a metal organic framework Pd 0.2 N i0.8 The MIL-101 emulsifier is prepared as follows: MIL-101 is dispersed in n-hexane, and a methanol solution of sodium chloropalladate and nickel chloride is added dropwise under ultrasonic and stirring, and the mixture is uniformly dispersed by ultrasonic and stirring, and then centrifuged and dried; sodium borohydride is added to methanol, and hydrogen is released from the sodium borohydride and the methanol, and the liquid with bubbles on the upper layer is quickly taken and added to the MIL-101, the sodium chloropalladate and the nickel chloride, and stirring is continued for 30 min, and then the mixture is washed with methanol and vacuum dried to obtain Pd

[0011] The technical scheme adopted by the present application is: a metal organic framework Pd 0.2 N i0.8 The MIL-101 emulsifier is prepared as follows: MIL-101 is dispersed in n-hexane, and a methanol solution of sodium chloropalladate and nickel chloride is added dropwise under ultrasonic and stirring, and the mixture is uniformly dispersed by ultrasonic and stirring, and then centrifuged and dried; sodium borohydride is added to methanol, and hydrogen is released from the sodium borohydride and the methanol, and the liquid with bubbles on the upper layer is quickly taken and added to the MIL-101, the sodium chloropalladate and the nickel chloride, and stirring is continued for 30 min, and then the mixture is washed with methanol and vacuum dried to obtain Pd 0.2 Ni 0.8 The MIL-101 emulsifier is prepared as follows: MIL-101 is dispersed in n-hexane, and a methanol solution of sodium chloropalladate and nickel chloride is added dropwise under ultrasonic and stirring, and the mixture is uniformly dispersed by ultrasonic and stirring, and then centrifuged and dried; sodium borohydride is added to methanol, and hydrogen is released from the sodium borohydride and the methanol, and the liquid with bubbles on the upper layer is quickly taken and added to the MIL-101, the sodium chloropalladate and the nickel chloride, and stirring is continued for 30 min, and then the mixture is washed with methanol and vacuum dried to obtain Pd 0.2 Ni 0.8 The MIL-101 emulsifier is prepared as follows: MIL-101 is dispersed in n-hexane, and a methanol solution of sodium chloropalladate and nickel chloride is added dropwise under ultrasonic and stirring, and the mixture is uniformly dispersed by ultrasonic and stirring, and then centrifuged and dried; sodium borohydride is added to methanol, and hydrogen is released from the sodium borohydride and the methanol, and the liquid with bubbles on the upper layer is quickly taken and added to the MIL-101, the sodium chloropalladate and the nickel chloride, and stirring is continued for 30 min, and then the mixture is washed with methanol and vacuum dried to obtain Pd

[0012] The above-mentioned bimetallic-based metal organic framework Pd 0.2 N i0.8 @Application of MIL-101 Pickering emulsion in catalyzing nitrobenzene reductive amination tandem reaction.

[0013] The above-mentioned application, the method is as follows, taking nitrobenzene, sodium borohydride and catalyst in a container for reaction, adding benzaldehyde, continuing to react for 20 min, the catalyst is the Pd of claim 6 0.2 Ni 0.8 @MIL-101 Pickering emulsion.

[0014] The above-mentioned application, the molar ratio of nitrobenzene, sodium borohydride and benzaldehyde is 1:2:1.2.

[0015] The above-mentioned application, the reaction is reacted at a temperature of 303K for 20 min.

[0016] The Pd 0.2 Ni 0.8 @In the MIL-101 Pickering emulsion, the palladium-nickel alloy provides metal site catalysis for the first step of nitrobenzene reduction reaction, and the MIL-101 provides rich acid sites (Cr clusters in MIL-101) to catalyze the second step reaction, thereby synergistically catalyzing the tandem reaction.

[0017]

[0018] The PdNi@MIL-101 Pickering emulsion provided by the application, Pd and Ni are attached in the pores of MIL-101, effectively preventing the aggregation of nanoparticles. By adding a second low-cost metal to adjust the electronic structure of the active site, the catalytic activity is improved. In addition, the Pd 0.2 Ni 0.8 @MIL-101 still maintains high catalytic activity, has high stability and recyclability. The Pd 0.2 Ni 0.8 @MIL-101 has excellent catalytic performance in the nitrobenzene reductive amination tandem reaction. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 is the optical microscope photo of the formed Pd 0.2 Ni 0.8 @MIL-101 Pickering emulsion.

[0020] Figure 2 is the Pd 0.2 Ni 0.8 @MIL-101 Pickering emulsion in the application. 0.2Ni 0.8 TEM image of MIL-101.

[0021] Figure 3 Pd@MIL-101 Pickering emulsion of the present invention 0.2 Ni 0.8 Pd content in MIL-101 Pickering emulsion 0.2 Ni 0.8 PXRD pattern of MIL-101 material.

[0022] Figure 4 Pd@MIL-101 Pickering emulsion of the present invention 0.2 Ni 0.8 Comparison of catalytic activity of MIL-101 Pickering emulsion, Pd@MIL-101 Pickering emulsion and Ni@MIL-101 Pickering emulsion in reduction of p-nitrobenzene reaction.

[0023] Figure 5 Pd@MIL-101 Pickering emulsion of the present invention 0.2 Ni 0.8 Catalytic activity of MIL-101 Pickering emulsion in five cycles of catalytic reaction.

[0024] Figure 6 Pd@MIL-101 Pickering emulsion of the present invention 0.2 Ni 0.8 Optical microscope image of emulsion formed by recovered catalyst after five cycles of catalytic reaction of MIL-101 Pickering emulsion. DETAILED DESCRIPTION

[0025] Example 1 A bimetallic based metal organic framework Pd@Ni@MIL-101 Pickering emulsion of the present invention 0.2 Ni 0.8 The preparation method of MIL-101 stabilized Pickering emulsion (I) is as follows:

[0026] 1. Synthesis of MIL-101 powder

[0027] Chromium nitrate nonahydrate (3.2 g, 0.008 mol) and terephthalic acid (1.312 g, 0.008 mol) were poured into a 80 ml hydrothermal synthesis reactor. Then 2.1708 mL of 99.95% glacial acetic acid and 40 mL of ultrapure water were accurately measured by a pipette and added to the reactor. The reactor was placed in an oven at 473 K for 8 h. After the reaction was completed, it was cooled to room temperature, washed with DMF three times, then washed with ethanol three times, and finally placed in a vacuum drying box at 423 K for 12 h to obtain the precursor MIL-101.

[0028] 2. Preparation of sodium chloropalladate solution and nickel chloride solution

[0029] Accurately weigh 0.12 g of palladium chloride solid, 0.044 g of sodium chloride solid into a 10 mL glass bottle, then add 4 mL of methanol to the bottle, slightly heat to completely dissolve, stir overnight. Obtain 0.17 mol / L of brownish brown sodium chloropalladate solution.

[0030] Accurately weigh 0.202 nickel chloride solid into a 5ml glass bottle, then add 1.85ml of methanol to the bottle, slightly heat to completely dissolve. Obtain 1.85mol / L of light green nickel chloride solution.

[0031] 3、Pd 0.2 Ni 0.8 @MIL-101 powder synthesis

[0032] Accurately weigh 200mg MIL-101 into a 100mL three-necked flask, accurately add 40mL of n-hexane with a pipette, ultrasonic for 15min to make it uniformly dispersed, drop 165ul of sodium chloropalladate solution and 185ul of nickel chloride solution under the condition of vigorous stirring, ultrasonic for 15min and stirring for 60min to make it uniformly mixed and dispersed, centrifugal dry; Accurately weigh 34.48mg of sodium borohydride solid into 20ml of methanol, sodium borohydride and methanol release hydrogen gas, quickly suck the upper layer of the bubble liquid into MIL-101, sodium chloropalladate and nickel chloride, continue to stir for 30min, wash with methanol three times, finally dry in a 333K vacuum oven for 6h, obtain Pd 0.2 Ni 0.8 @MIL-101 material;

[0033] 4、Pd@MIL-101、Ni@MIL-101 powder synthesis

[0034] Accurately weigh 200mg MIL-101 into a 100mL three-necked flask, accurately add 40mL of n-hexane with a pipette, ultrasonic for 15min to make it uniformly dispersed, drop 165ul of sodium chloropalladate solution and 185ul of nickel chloride solution under the condition of vigorous stirring, ultrasonic for 15min and stirring for 60min to make it uniformly mixed and dispersed, centrifugal dry; Accurately weigh 34.48mg of sodium borohydride solid into 20ml of methanol, sodium borohydride and methanol release hydrogen gas, quickly suck the upper layer of the bubble liquid into MIL-101, sodium chloropalladate and nickel chloride, continue to stir for 30min, wash with methanol three times, finally dry in a 333K vacuum oven for 6h, obtain Pd

[0035] 5、Pd 0.2 Ni 0.8Preparation of Pickering emulsion stabilized by MIL-101, Pd@MIL-101, Ni@MIL-101

[0036] Into 25 mg of Pd 0.2 Ni 0.8 @MIL-101, 2 mL of toluene and 3 mL of deionized water were added, and after ultrasonic treatment at a power of 100 W for 5 min, the mixture was shaken vigorously for 5 min to prepare Pd 0.2 Ni 0.8 @MIL-101, Pd@MIL-101, and Ni@MIL-101 stabilized Pickering emulsion.

[0037] (ii) Detection

[0038] Figure 1 The Pd 0.2 Ni 0.8 @MIL-101 Pickering emulsion was observed under an optical microscope. As can be seen, the Pd 0.2 Ni 0.8 @MIL-101 Pickering emulsion droplets were uniformly dispersed and had uniform sizes.

[0039] Figure 2 The transmission electron microscopy (TEM) image of the Pd 0.2 Ni 0.8 @MIL-101 material showed that the Pd and Ni nanoparticles were uniformly dispersed in the Pd 0.2 Ni 0.8 @MIL-101 material.

[0040] Figure 3 The X-ray diffraction (PXRD) pattern of the Pd 0.2 Ni 0.8 @MIL-101 material showed that the Pd 0.2 Ni 0.8 @MIL-101 material had good crystallinity during the synthesis and preparation process.

[0041] Example 2 Catalytic function of Pd 0.2 Ni 0.8 @MIL-101 material on the reduction and amination tandem reaction of nitrobenzene (I) The Pd 0.2 Ni 0.8 @MIL-101 Pickering emulsion stabilized by a bimetallic metal-organic framework prepared in Example 1 was used as a catalyst to catalyze the reduction and amination tandem reaction of nitrobenzene

[0042] The method is as follows:

[0043] The Pd0.2 Ni 0.8 @MIL-101 Pickering emulsion was added into a 10 mL three-necked reaction vessel, followed by the addition of 1.0 mmol of nitrobenzene and 2 mmol of sodium borohydride, and the reaction was allowed to proceed at a temperature of 303 K for 20 min. Then, 1.2 mmol of benzaldehyde was added, and the reaction was allowed to proceed for 20 min to produce a N-benzylidene aniline derivative. As a comparison, Pd@MIL-101 or Ni@MIL-101 stabilized Pickering emulsion obtained in Example 1, step 5 was added into a 10 mL three-necked reaction vessel, followed by the addition of 1.0 mmol of nitrobenzene and 2 mmol of sodium borohydride, and the reaction was allowed to proceed at a temperature of 303 K for 20 min. The yield of the product was monitored by gas chromatography (GC).

[0044] During the reaction, Pd 0.2 Ni 0.8 @MIL-101 stabilized Pickering emulsion was added into a 10 mL three-necked reaction vessel, followed by the addition of 1.0 mmol of nitrobenzene and 2 mmol of sodium borohydride, and the reaction was allowed to proceed at a temperature of 303 K for 20 min. Then, 1.2 mmol of benzaldehyde was added, and the reaction was allowed to proceed for 20 min to produce a N-benzylidene aniline derivative. As a comparison, Pd@MIL-101 or Ni@MIL-101 stabilized Pickering emulsion obtained in Example 1, step 5 was added into a 10 mL three-necked reaction vessel, followed by the addition of 1.0 mmol of nitrobenzene and 2 mmol of sodium borohydride, and the reaction was allowed to proceed at a temperature of 303 K for 20 min. The yield of the product was monitored by gas chromatography (GC).

[0045] During the reaction, Pd 0.2 Ni 0.8 @MIL-101 stabilized Pickering emulsion was added into a 10 mL three-necked reaction vessel, followed by the addition of 1.0 mmol of nitrobenzene and 2 mmol of sodium borohydride, and the reaction was allowed to proceed at a temperature of 303 K for 20 min. Then, 1.2 mmol of benzaldehyde was added, and the reaction was allowed to proceed for 20 min to produce a N-benzylidene aniline derivative. As a comparison, Pd@MIL-101 or Ni@MIL-101 stabilized Pickering emulsion obtained in Example 1, step 5 was added into a 10 mL three-necked reaction vessel, followed by the addition of 1.0 mmol of nitrobenzene and 2 mmol of sodium borohydride, and the reaction was allowed to proceed at a temperature of 303 K for 20 min. The yield of the product was monitored by gas chromatography (GC).

[0046] After the reaction, the reaction mixture was centrifuged and filtered to separate Pd 0.2 Ni 0.8 @MIL-101, washed with ethanol, filtered, and dried. The Pd 0.2 Ni 0.8 @MIL-101 material was recovered.

[0047] The recovered Pd 0.2 Ni 0.8 @MIL-101 material was used to prepare a Pickering emulsion to catalyze the reductive amination reaction of nitrobenzene.

[0048] The experimental results are shown in Figure 4 , Figure 5 and Figure 6 . Figure 4 is a comparison chart of the catalytic activities of Pd 0.2 Ni 0.8 @MIL-101, Pd@MIL-101, and Ni@MIL-101 stabilized Pickering emulsion. The yield and conversion rate of the bimetallic Pd 0.2 Ni 0.8 @MIL-101 Pickering emulsion are higher than those of the monometallic Pd@MIL-101 and Ni@MIL-101 Pickering emulsion. Figure 5 is a comparison chart of the catalytic activities of Pd0.2 Ni 0.8 @The catalytic activity graph of MIL-101 Pickering emulsion in five cycles of catalytic reaction, after 5 cycles of experiments, the yield and conversion rate are higher than 95%, indicating that the activity of the catalyst has not decreased significantly, Figure 6 is Pd 0.2 Ni 0.8 @The optical microscope image of the emulsion formed by the recovered catalyst after five cycles of catalytic reaction of MIL-101 Pickering emulsion, from the figure, it can be seen that the recovered catalyst can still form Pickering emulsion stably. It shows that Pd 0.2 Ni 0.8 @MIL-101 can be recycled as a catalyst for the reduction and amination of nitrobenzene.

Claims

1. A bimetal-based metal organic framework Pd 0.2 Ni 0.8 @The application of MIL-101 Pickering emulsion in catalytic nitrobenzene reductive amination tandem reaction is characterized in that, To Pd 0.2 Ni 0.8 @MIL-101 emulsifier, after ultrasonic, shake vigorously, Pd 0.2 Ni 0.8 @MIL-101 stable pickering emulsion, Pd 0.2 Ni 0.8 @MIL-101 emulsifier is prepared as follows: MIL-101 is dispersed in n-hexane, ultrasonic, under the condition of vigorous stirring, drop into sodium chloropalladate and nickel chloride methanol solution, ultrasonic and stirring mixed dispersion uniform, centrifugal drying; sodium borohydride is added to methanol, sodium borohydride and methanol release hydrogen, quickly suck the upper liquid with bubbles and add to MIL-101, sodium chloropalladate and nickel chloride, continue to stir 30 min, washed with methanol, vacuum drying, Pd 0.2 Ni 0.8 @MIL-101 emulsifier.

2. Use according to claim 1, characterized in that, MIL-101 : Pd : Ni = 500 : 2 : 8 by mass ratio.

3. Use according to claim 1, characterized in that, The preparation method of MIL-101 is as follows: chromium nitrate nonahydrate, terephthalic acid, glacial acetic acid and ultrapure water are added into a hydrothermal synthesis reaction kettle for reaction, and after the reaction is completed, it is cooled to room temperature, and then washed with DMF and anhydrous ethanol in sequence, and dried in vacuum to obtain the precursor MIL-101.

4. Use according to claim 3, characterized in that, The molar ratio of chromium nitrate nonahydrate to terephthalic acid is 1:

1.

5. Use according to claim 3, characterized in that, The reaction is carried out in an oven at 473 K for 8 h.

6. Use according to claim 1, characterized in that, The process is as follows, taking nitrobenzene, sodium borohydride and catalyst in a container to react, adding benzaldehyde, continuing to react for 20 min, and the catalyst is Pd 0.2 Ni 0.8 @MIL-101 pickering emulsion.

7. Use according to claim 6, characterized in that, The molar ratio of nitrobenzene, sodium borohydride and benzaldehyde is 1:2:1.

2.

8. Use according to claim 6, characterized in that, The reaction is carried out at a temperature of 303 K for 20 min.

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