CN104307515B

CN104307515B - A kind of Au-Pd/ graphen catalyst and its preparation method and application

Info

Publication number: CN104307515B
Application number: CN201410460077.7A
Authority: CN
Inventors: 张燕辉; 高飞
Original assignee: Minnan Normal University
Current assignee: Minnan Normal University
Priority date: 2014-09-11
Filing date: 2014-09-11
Publication date: 2016-06-15
Anticipated expiration: 2034-09-11
Also published as: CN104307515A

Abstract

The invention provides a kind of Au-Pd/ graphen catalyst and its preparation method and application, with graphene oxide, HAuCl₄、H₂PdCl₄And NaBH₄For raw material, prepare Au-Pd bimetallic alloy load graphen catalyst through a step backflow. Au-Pd/ graphen catalyst is used for solvent-free thermal catalytic selectivity Oxybenzene methanol and catalysis reduction paranitroanilinum by the present invention first, has high catalytic efficiency and high selectivity. This method for preparing catalyst is simple, with low temperature heat energy for driving energy, reduces for organic selective oxidation, is conducive to the sustainable development of environment and the energy.

Description

A kind of Au-Pd/ graphen catalyst and its preparation method and application

Technical field

The invention belongs to the sustainable development field of catalyst preparing and environment and the energy, be specifically related to the preparation of a kind of Au-Pd/ graphen catalyst and catalytic selectivity Oxybenzene methanol to benzaldehyde and reduction paranitroanilinum to p-phenylenediamine.

Background technology

Compared with one-component metal, structure and the electronic property of bimetallic alloy are significantly different, and then, bimetallic alloy has obvious advantage for the activity and selectivity improving catalysis. But, traditional method synthesis two-metal alloy nanoparticle usually requires that use surfactant removes the bimetallic alloy colloid of synthesizing stable as protective agent, then becomes catalyst by Alloy on carrier. Therefore, it is desirable to directly synthesize the bimetallic alloy particle without stabilizer modification original position load simultaneously in the solution on carrier for catalytic applications.

Although some researchs are it have been reported that monometallic or bimetallic particle load are on the surface of Graphene or graphene oxide, but in building-up process, these researchs still use the formation of surfactant, polymer and polyelectrolyte deprotection bimetallic alloy particle. At this, we have found that when not adding surfactant, polymer, polyelectrolyte, dendrimer or ligand, solution is using graphene oxide as platform, achieve one-step synthesis bimetal Au-Pd Nanoalloy, and first Au-Pd/ Graphene (Au-Pd/GR) is oxidized to aldehydes for alcohols selectivity and substituted-nitrobenzene reverts to amine. Obtain alcohols and amine organic compound is very important, because aldehydes and amine are as the intermediate of important chemical products, be widely used in the industrial circles such as medicine, dyestuff, spice, pesticide and material.

Summary of the invention

It is an object of the invention to provide a kind of catalysis activity and selectivity height, good cycle, cost of manufacture is low, production technology is simple, can macroscopic view preparation, eco-friendly Au-Pd/GR Catalysts and its preparation method and application, the bimetal Au-Pd/GR of preparation has catalytic selectivity Oxybenzene methanol to corresponding aldehyde and the paranitroanilinum feature to p-phenylenediamine and easy recovery of reducing.

Described benzyl alcohol and benzaldehyde structure are as follows:

Described paranitroanilinum and p-phenylenediamine structure are as follows:

For achieving the above object, the present invention adopts the following technical scheme that

A kind of Au-Pd/ graphen catalyst is to be carried on equably on Graphene by bimetallic alloy Au-Pd.

Its preparation method comprises the following steps:

(1) by graphene oxide ultrasonic disperse in deionized water, HAuCl is added₄Solution and H₂PdCl₄Solution, and stir 0.5h;

(2) step (1) gained mixed solution is slowly added dropwise NaBH while stirring₄Solution;

(3) reflux 24h by step (2) gained reactant liquor 100 DEG C, filters, washs, is drying to obtain Au-Pd/ graphen catalyst.

Described Au-Pd/ graphen catalyst is for solvent-free thermal catalytic selectivity Oxybenzene methanol to benzaldehyde and reduction paranitroanilinum to p-phenylenediamine.

Catalytic oxidation specifically comprises the following steps that

(1) a certain amount of catalyst and a certain amount of benzyl alcohol joined in 100mL heat catalysis still and stir;

(2) temperature of reaction needed, rotating speed and pressure are regulated, after reaction certain time, centrifugal, reclaim catalyst, and take a certain amount of product ethanol dilution, treat air inlet analysis of hplc;

(3) by reaction mixture air inlet analysis of hplc, by retention time and peak area qualitative, quantitative.

Catalysis reduction specifically comprises the following steps that

(1) a certain amount of p-nitrophenyl amine aqueous solution is placed in beaker, adds a certain amount of NaBH₄;

(2) after stirring, adding catalyst, after reaction certain time, filter, reaction mixture treats uv-visible absorption spectra analysis;

(3) reaction mixture is analyzed by uv-visible absorption spectra, undertaken quantitatively by specific peak absorbance peak.

Described Au-Pd/ graphen catalyst is when 100 DEG C, 3 atmospheres oxygen and 1500 revs/min, and benzyl alcohol catalytic reaction 8h, its conversion ratio is 86%, and the selectivity obtaining benzaldehyde is 83%.

Described Au-Pd/ graphen catalyst is at room temperature 25 DEG C and NaBH₄Under solution condition, paranitroanilinum catalytic reaction 4min, its conversion ratio is 98%, and the selectivity obtaining p-phenylenediamine is 98%.

The present invention has the great advantage that

(1) Au-Pd/GR catalyst is used for catalytic selectivity Oxybenzene methanol and reduction paranitroanilinum by the present invention first, has high catalytic efficiency, and corresponding a kind of product is had high selectivity.

(2) preparation is simple, with low temperature heat energy for drive can, for the reduction of the oxidation of benzyl alcohol and paranitroanilinum, be conducive to the sustainable development of environment and the energy.

(3) Au-Pd/GR catalyst photocatalytic activity and selectivity height, good cycle, cost of manufacture is low, production technology is simple, can macroscopic view preparation, environmental friendliness, easily reclaim.

Accompanying drawing explanation

Fig. 1 is the XRD figure of Au/GR, Pd/GR and Au-Pd/GR.

Fig. 2 is the TEM (a) of Au-Pd/GR, statistics Au-Pd particle size distribution (b), HRTEM (c) and EDS energy spectrum analysis (d) figure.

Fig. 3 is the x-ray photoelectron spectroscopy figure of Au-Pd/GR.

Detailed description of the invention

Embodiment 1

By the graphene oxide ultrasonic disperse of 95mg in 100mL deionized water, it is subsequently added the HAuCl of 1.27mL10mM₄H with 2.35mL10mM₂PdCl₄Solution, and stir 0.5h. When stirring, slowly drip the NaBH of 50mL0.15M₄Solution, is then heated to 100 DEG C of backflow 24h by reactant liquor. Reaction is after end is cooled to room temperature, adopt the method filtered to make solid-liquid separation, by solids washed with water, be placed in 60 DEG C of baking ovens to dry to obtain 2.5wt%Au-2.5wt%Pd/GR catalyst. In order to compare, only add single metal front salt under identical condition and be respectively synthesized 5wt%Au/GR and 5wt%Pd/GR catalyst. In 100mL heat catalysis still, add 50mg catalyst and 20mL benzyl alcohol and be uniformly mixed, heat catalysis condition is then set, the temperature of reaction is 100 DEG C, stir speed (S.S.) is 1500 revs/min and pressure is 3 atmospheres oxygen, carrying out along with reaction, benzyl alcohol is converted into benzaldehyde, and relevant data are as shown in table 1.

Table 1 is Au-Pd/GR, Au/GR and the Pd/GR catalyst Oxybenzene methanol activity to benzaldehyde

Embodiment 2

By the graphene oxide ultrasonic disperse of 95mg in 100mL deionized water, it is subsequently added the HAuCl of 1.27mL10mM₄H with 2.35mL10mM₂PdCl₄Solution, and stir 0.5h. When stirring, slowly drip the NaBH of 50mL0.15M₄Solution, is then heated to 100 DEG C of backflow 24h by reactant liquor. Reaction is after end is cooled to room temperature, adopt the method filtered to make solid-liquid separation, by solids washed with water, be placed in 60 DEG C of baking ovens to dry to obtain 2.5wt%Au-2.5wt%Pd/GR catalyst. In order to compare, only add single metal front salt under identical condition and be respectively synthesized 5wt%Au/GR and 5wt%Pd/GR catalyst. By the NaBH of 80mg₄Paranitroanilinum mix homogeneously with 160mL concentration is 10ppm, adds the catalyst of 5mg, and along with the carrying out of catalytic reaction, paranitroanilinum is reduced to p-phenylenediamine, and relevant data are as shown in table 2.

Table 2 is Au-Pd/GR, Au/GR and the Pd/GR catalyst reduction paranitroanilinum activity to p-phenylenediamine

Fig. 1 is the XRD figure of Au/GR, Pd/GR and Au-Pd/GR. It will be seen that Au-Pd, Au and the Pd morphology of particles obtained is face-centered cubic from Fig. 1, and all diffraction maximums of bimetal Au-Pd are all located at monometallic Au and the centre position of monometallic Pd, illustrate to define Au-Pd alloy.

Fig. 2 is the TEM (a) of Au-Pd/GR, statistics Au-Pd particle size distribution (b), HRTEM (c) and EDS energy spectrum analysis (d) figure. It will be seen that define the bimetal Au-Pd alloy that particle size is 2-28nm be well dispersed in graphenic surface from Fig. 2, and the metallic formed by EDS analysis verification contains two kinds of components of Au and Pd.

Fig. 3 is the x-ray photoelectron spectroscopy figure of Au-Pd/GR. It will be seen that noble metal species are quantivalence is the metallic state of 0 valency from Fig. 3.

The foregoing is only presently preferred embodiments of the present invention, all equalizations done according to the present patent application the scope of the claims change and modify, and all should belong to the covering scope of the present invention.

Claims

1. the application of an Au-Pd/ graphen catalyst, it is characterised in that: by the graphene oxide ultrasonic disperse of 95mg in 100mL deionized water, it is subsequently added the HAuCl of 1.27mL10mM₄H with 2.35mL10mM₂PdCl₄Solution, and stir 0.5h, when stirring, slowly drip the NaBH of 50mL0.15M₄Solution, is then heated to 100 DEG C of backflow 24h by reactant liquor, and reaction is after end is cooled to room temperature, adopt the method filtered to make solid-liquid separation, by solids washed with water, be placed in 60 DEG C of baking ovens to dry to obtain 2.5wt%Au-2.5wt%Pd/ graphen catalyst; Obtained 2.5wt%Au-2.5wt%Pd/ graphen catalyst is for solvent-free thermal catalytic selectivity Oxybenzene methanol to benzaldehyde and reduction paranitroanilinum to p-phenylenediamine: in 100mL heat catalysis still, add 50mg2.5wt%Au-2.5wt%Pd/ graphen catalyst and 20mL benzyl alcohol and be uniformly mixed, described 2.5wt%Au-2.5wt%Pd/ graphen catalyst is when 100 DEG C, 3 atmospheres oxygen and 1500 revs/min, benzyl alcohol catalytic reaction 8h, its conversion ratio is 86%, and the selectivity obtaining benzaldehyde is 83%; By the NaBH of 80mg₄With the paranitroanilinum mix homogeneously that 160mL concentration is 10ppm, add the 2.5wt%Au-2.5wt%Pd/ graphen catalyst of 5mg, described 2.5wt%Au-2.5wt%Pd/ graphen catalyst is at room temperature 25 DEG C and NaBH₄Under solution condition, paranitroanilinum catalytic reaction 4min, its conversion ratio is 98%, and the selectivity obtaining p-phenylenediamine is 98%.