CN111450885B

CN111450885B - Metal organic framework UIO-66(Ce) loaded ruthenium catalyst and preparation method and application thereof

Info

Publication number: CN111450885B
Application number: CN201910054778.3A
Authority: CN
Inventors: 陆国平; 李欣欣
Original assignee: Nanjing University of Science and Technology
Current assignee: Nanjing University of Science and Technology
Priority date: 2019-01-21
Filing date: 2019-01-21
Publication date: 2022-03-22
Anticipated expiration: 2039-01-21
Also published as: CN111450885A

Abstract

The invention discloses a ruthenium catalyst loaded by a metal organic framework UiO-66(Ce), a preparation method and application thereof in a reaction of dehydrogenating primary amine to generate nitrile under the condition of no oxidant and no proton acceptor. The invention takes UiO-66(Ce) as a carrier, adopts a chemical adsorption reduction loading method and adopts NaBH₄The ruthenium chloride is reduced to prepare the metal organic framework UiO-66(Ce) supported ruthenium catalyst. The ruthenium catalyst loaded by the metal organic framework UiO-66(Ce) has high catalytic activity, can be recycled, has excellent catalytic performance in the reaction of generating nitrile by dehydrogenating primary amine, replaces an organic reagent with green solvent water in the catalytic reaction process, can be recycled, and reduces the environmental pollution.

Description

Metal organic framework UIO-66(Ce) loaded ruthenium catalyst and preparation method and application thereof

Technical Field

The invention belongs to the technical field of catalytic hydrogenation, and relates to a ruthenium catalyst loaded by a metal organic framework UiO-66(Ce), a preparation method and application thereof in a reaction of dehydrogenating primary amine to generate nitrile under the condition of no oxidant and no proton acceptor.

Background

Metal-Organic Frameworks (MOFs), abbreviated as MOFs, are Organic-inorganic hybrid materials with intramolecular pores formed by self-assembly of Organic ligands and Metal ions or clusters through coordination bonds, and have three main characteristics: (1) porosity and large specific surface area; (2) structural and functional diversity; (3) unsaturated metal sites, exhibiting different adsorption properties, catalytic properties, optical properties, electromagnetic properties, etc. The porous structure fixed by the MOFs material and the larger specific surface area provide natural physical space for loading the high-dispersion catalyst, and the porous structure enables the catalyst to be more fully contacted with reactants, thereby being beneficial to the reaction.

Metal catalysts are a large branch of heterogeneous catalysts, and transition metals, rare earth metals, and many other metals can be used as catalysts. However, the metal nanoparticles are easy to agglomerate, so that the metal nanoparticles are not in sufficient contact with reactants, and the catalytic performance of the metal nanoparticles is greatly reduced. And the metal nano-particle catalyst can be dispersed on MOFs to obtain a highly dispersed and extremely stable metal catalyst, so that the practicability of the metal nano-particle catalyst in various catalysis fields can be greatly improved.

Dehydrogenation of hydrogen-rich organic compounds is in most cases a thermodynamically unfavorable process, and therefore dehydrogenation of organic compounds usually requires stoichiometric or excess amounts of oxidizing agents, such as oxygen, peroxides, iodates, and metal oxides or proton acceptors, to produce by-products, which are polluting and wasteful. In contrast, the acceptor-free dehydrogenation of organic compounds does not require stoichiometric amounts of oxidizing agents, catalytically cleaves C-H, N-H or O-H bonds to directly release hydrogen, and is an economical and green manner. Primary amine acceptor-free dehydrogenation has been reported: (1) the NNN-Ru (II) hydride complex of the amide derivative can catalyze primary amine and secondary amine to selectively dehydrogenate under the conditions of no oxidant and no proton acceptor to obtain corresponding nitrile and imine, and simultaneously release hydrogen, but the catalyst cannot be recycled, so that the waste of noble metal is caused, and a toxic reagent is used to cause environmental pollution (J.Am.chem.Soc.2013,135: 16352-); (2) the application of acceptor-free dehydrogenation and related transformations in chemical synthesis is discussed in combination, stating the selective catalysis of dehydrogenation reactions by transition metal complexes, and the application of further transformations of intermediates in reversible dehydrogenation processes (science.2013,341, 1229712); (3) under mild temperature conditions, Ru complexes with pyrazole ligands can catalyze the acceptor-free dehydrogenation of primary amines to form corresponding nitriles, but reaction auxiliaries (J.Am.chem.Soc.2018,140,8662-8666) are added in the reaction.

Disclosure of Invention

Aiming at the problems of high toxicity of a used solvent, unrecoverable catalyst and residual metal pollution in the existing primary amine acceptor-free dehydrogenation process, the invention provides the recyclable ruthenium catalyst supported by the metal organic framework UiO-66(Ce) and the preparation method thereof, wherein the catalyst has good catalytic effect on the reaction of primary amine acceptor-free dehydrogenation to generate nitrile, has longer service life, can be recycled and reused, and does not influence the yield.

The technical solution of the invention is as follows:

the preparation method of the metal organic framework UiO-66(Ce) supported ruthenium catalyst comprises the following specific steps:

sequentially adding ruthenium chloride and L-lysine solution into aqueous solution of UiO-66(Ce), stirring and mixing uniformly at room temperature, and slowly dropwise adding NaBH under the ice bath condition₄And stirring the solution until the solution is fully reduced, adding acetone, standing for aging, centrifuging, respectively cleaning with water and ethanol, and drying to obtain the metal organic framework UiO-66(Ce) -loaded ruthenium catalyst.

Preferably, the concentration of the L-lysine solution is 0.5-0.6M.

Preferably, the NaBH₄The concentration of the solution is 0.5-1.0M.

Preferably, the standing and aging time is 24-36 h.

Preferably, the loading amount of ruthenium in the catalyst is 0.8-1.0 wt%.

The invention provides a metal organic framework UiO-66(Ce) loaded ruthenium catalyst prepared by the preparation method.

The invention also provides application of the metal organic framework UiO-66(Ce) supported ruthenium catalyst in the reaction of primary amine non-acceptor dehydrogenation to generate nitrile.

Further, the application of the metal organic framework UiO-66(Ce) supported ruthenium catalyst in the reaction of primary amine non-acceptor dehydrogenation to generate nitrile comprises the following specific steps:

adding primary amine and a ruthenium catalyst loaded by a metal organic framework UiO-66(Ce) into water, reacting at 100-130 ℃ under the condition of argon, cooling to room temperature after the reaction is finished, and extracting with ethyl acetate to obtain a reaction product.

The primary amine may be

n＝4～14；

R＝H，3-CH₃；

Preferably, the molar ratio of primary amine to ruthenium is 1: 0.008.

Preferably, the reaction time is 12-24 h.

Compared with the prior art, the invention has the following advantages:

(1) the porous metal organic framework UiO-66(Ce) is adopted as a catalyst carrier, and the interaction between metal ruthenium and the carrier obviously improves the activity of the catalyst;

(2) the UiO-66(Ce) is firmly combined with the ruthenium nano-particles, is not easy to inactivate and agglomerate, and can be recycled in the application of primary amine acceptor-free dehydrogenation to generate nitrile;

(3) the catalyst provided by the invention has excellent catalytic performance for the reaction of primary amine acceptor-free dehydrogenation to generate nitrile, is high in yield, economic and environment-friendly, and improves the use efficiency of the noble metal catalyst.

Drawings

FIG. 1 is a TEM image of a UiO-66(Ce) supported ruthenium catalyst.

Detailed Description

The present invention will be described in more detail with reference to the following examples and the accompanying drawings.

In the following examples, UiO-66(Ce) is prepared according to the following steps, which are described in [ chem.commun.,2015,51, 12578-12581 ]: terephthalic acid (708mg) was dissolved in N, N-dimethylformamide (24mL), 8mL of a cerium ammonium nitrate (0.53M) solution was added with stirring at room temperature, stirred at 100 ℃ for 30min, cooled to room temperature, the mixture cooled to room temperature was centrifuged to give a pale yellow precipitate, which was washed 4 times with N, N-dimethylformamide (40mL) and acetone (40mL), and finally immersed in methanol (50mL) to remove the solvent, dried, and activated at 100 ℃ under vacuum for 24h to give UiO-66 (Ce).

Example 1

1. Preparation of metal organic framework UiO-66(Ce) supported ruthenium catalyst:

adding ruthenium chloride (0.024mmol) into 25ml of aqueous solution of LuiO-66(Ce) (500mg), adding 0.53M L-lysine solution, stirring at room temperature for 4h, and slowly adding NaBH dropwise under ice-bath condition₄Reducing metal ions with solution (0.50M), stirring for 1-2 hr, adding acetone (5mL), standing, aging for 24 hr, centrifuging to obtain solid, washing with deionized water and ethanol for three times, and standing under vacuumAnd (3) drying the catalyst for 12 hours at the temperature of 60 ℃ in an air drying oven to prepare the metal organic framework UiO-66(Ce) supported ruthenium catalyst.

Use of a UiO-66(Ce) -supported ruthenium catalyst in a primary amine acceptor-free dehydrogenation to nitrile reaction:

0.20mmol of primary amine 1 and 1.6 mol% of UiO-66(Ce) -supported ruthenium catalyst were sequentially added to an anhydrous oxygen-free tube, 1mL of water was added, the reaction was carried out at 130 ℃ under argon for 16 hours, the reaction was completed, the reaction was cooled to room temperature, extraction was carried out with ethyl acetate, and the yields of the products 2a to 2 hours, as shown in Table 1, were 72%, 93%, 60%, 62%, 25%, 100%, 64%, and 86%, respectively, as determined by GC-MS and GC.

The synthetic route of catalyzing primary amine acceptor-free dehydrogenation to generate nitrile by using a ruthenium catalyst loaded by UiO-66(Ce) as a representative by using primary amine 1a is as follows:

TABLE 1 Primary amine substrates and their products corresponding to the acceptor-free dehydrogenation

Comparative example 1

This comparative example is essentially the same as example 1, except that the supported metal is palladium.

Comparative example 2

This comparative example is essentially the same as example 1, except that the supporting metal is platinum.

Comparative example 3

This comparative example is essentially the same as example 1, except that the support was MIL-101 (Fe).

Comparative example 4

This comparative example is essentially the same as example 1, except that the carrier is MIL-125 (Ti).

Comparative example 5

This comparative example is essentially the same as example 1, except that the support is UiO-66 (Zr).

TABLE 2 catalysts and corresponding yields

	Catalyst and process for preparing same	Yield (%)
			Example 1	Ru/UiO-66(Ce)	72
Comparative example 1	Pd/UiO-66(Ce)	6
			Comparative example 2	Pt/UiO-66(Ce)	nr
Comparative example 3	Ru/MIL-101(Fe)	43
			Comparative example 4	Ru/MIL-125(Ti)	34
Comparative example 5	Ru/UiO-66(Zr)	41

The catalysts prepared in each example and comparative example and their yields in catalyzing the acceptor-free dehydrogenation of primary amine 1a to 2a product are shown in table 2. As can be seen from Table 2, when UiO-66(Ce) is used as a carrier and different ruthenium, platinum and palladium are loaded, the catalytic effect is best when only ruthenium metal is loaded, the yield is 72%, and the platinum and palladium loading has no catalytic effect basically. When different supports UiO-66(Ce), MIL-101(Fe), MIL-125(Ti) and UiO-66(Zr) are used for respectively loading the same metal ruthenium, the catalytic effect of only UiO-66(Ce) loading metal ruthenium is the best, and the catalytic effect of other supports loading metal ruthenium is not ideal. Therefore, the catalyst with the best catalytic effect is obtained when Ru/UiO-66(Ce) is adopted through the optimization of the conditions of the metal and the carrier.

Claims

1. The application of the ruthenium catalyst loaded by the metal organic framework UiO-66(Ce) in the reaction of generating nitrile by primary amine without receptor dehydrogenation is characterized in that the specific method is as follows:

adding primary amine and a ruthenium catalyst loaded by a metal organic framework UiO-66(Ce) into water, reacting at 100-130 ℃ under the condition of argon, cooling to room temperature after the reaction is finished, and extracting with ethyl acetate to obtain a reaction product;

the metal organic framework UiO-66(Ce) loaded ruthenium catalyst is prepared by the following steps:

2. Use according to claim 1, wherein said primary amine is

N =4~14 or

，R=H、3-CH₃Or

。

3. The use according to claim 1, wherein the molar ratio of primary amine to ruthenium is 1:0.008, and the reaction time is 12-24 hours.

4. The use according to claim 1, wherein the concentration of the L-lysine solution is 0.5 to 0.6M.

5. The use of claim 1 in which the NaBH is₄The concentration of the solution is 0.5-1.0M.

6. The use according to claim 1, wherein the standing aging time is 24-36 h.

7. The use according to claim 1, wherein the loading of ruthenium in the catalyst is 0.8-1.0 wt%.