CN109772455A

CN109772455A - A kind of preparation and application of the porous polyamine composite material wrapping up tiny high dispersive Pd nano particle

Info

Publication number: CN109772455A
Application number: CN201910195148.8A
Authority: CN
Inventors: 李留义; 杨鑫怡; 于岩
Original assignee: Fuzhou University
Current assignee: Fuzhou University
Priority date: 2019-03-14
Filing date: 2019-03-14
Publication date: 2019-05-21
Anticipated expiration: 2039-03-14
Also published as: CN109772455B

Abstract

The present invention proposes the preparation and application of a kind of porous polyamine composite material for wrapping up tiny high dispersive Pd nano particle, it is that precursor synthesizes a kind of porous polyamine composite material for wrapping up tiny high degree of dispersion Pd nano particle using covalent organic frame material, production hydrogen is decomposed for being catalyzed ammonia borine, has certain help for solving nowadays clean energy resource scarcity.Porous polyamino compound and palladium ion carry out coordination to stablize palladium ion, and stable palladium ion is reduced into tiny Pd nano particle by one-step method reduction while generating polyamine connexon.Porous polyamine composite material can be effectively stable and protection Pd nano particle is reunited in catalysis reaction, entirely prepares simply, and catalytic effect is excellent, has very active influence to catalysis reaction.

Description

A kind of preparation for the porous polyamine composite material wrapping up tiny high dispersive Pd nano particle And application

Technical field

The invention belongs to nano material preparation and catalytic field, it is related to a kind of wrapping up tiny high degree of dispersion Pd nano particle The synthesis and application of porous polyamine composite material.

Background technique

In recent years, solving energy problem is great challenge for human, develops novel clean energy resource and becomes and works as One of modern popular research direction.It is clear to become most promising green due to its high-energy density and reproducibility for hydrogen The clean energy, but the storage and release for hydrogen are still a challenge.Ammonia borine is with its high hydrogen content and excellent stabilization The advantages such as property, become most potential hydrogen storage material.It is well known that metal nanoparticle, which produces hydrogen for the catalysis of ammonia borine, to be had Very big facilitation, but metal nanoparticle group of being easy due to higher surface energy during being catalyzed reaction It is poly-, so as to cause the decline of catalytic cycle performance.Therefore, synthesis has high stability and active based on metal nanoparticle Composite catalyst is still a problem to be solved.

Summary of the invention

It is an object of the invention to overcome the shortage of prior art, a kind of tiny high degree of dispersion Pd nano particle of package has been synthesized Porous polyamine composite material and its catalysis ammonia borine decompose produce hydrogen.Using known covalent organic frame material and metal ion It is mutually coordinated, is re-introduced into reducing agent, by simple heating and stirring process, synthesizes and be wrapped in the shell of porous polyamine object Tiny and high dispersive Pd nano particle.

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

A kind of preparation method for the porous polyamine composite material wrapping up tiny high degree of dispersion Pd nano particle, includes the following steps:

(1) in methylene chloride by palladium acetate and COF-LZU1 dispersion, imine linkage and divalent palladium network are realized by way of stirring It closes, and is collected by filtration, be freeze-dried；

(2) solid obtained above is dispersed in 70 DEG C of stirrings in a certain proportion of tetrahydrofuran and the mixed liquor of deionized water, And excessive sodium borohydride solids are added thereto and are restored, continuous heating stirs 24 hours, collects solid tetrahydrofuran It respectively washs with deionized water and is dried overnight for 70 DEG C three times, the porous polyamine for obtaining wrapping up tiny high degree of dispersion Pd nano particle is compound Material Pd@H-PPA；

The volume ratio of the tetrahydrofuran and deionized water is 4:1.

It is heating and stirring by the mode that Pd nano particle is wrapped in porous polyamine shell.

Obtained Pd nano particle mean size is that 2.6 nm sizes are small, and are highly dispersed at the shell of porous polyamine materials In the middle.

Using: Pd@H-PPA catalyst generates hydrogen for being catalyzed ammonia borine, and synthesized catalyst is put into ammonia boron In the aqueous solution of alkane, reaction temperature is 25 ~ 45 DEG C, shows the recyclable excellent properties of efficient stable.

The present invention has the advantages that

The divalent palladium ion that will be coordinated with imine linkage in COF-LZU1 using one-step method, in-situ reducing become tiny palladium nanoparticle Son, while imine linkage is also reduced into secondary amine key.Easy to operate, preparation flow is simple；And prepared composite material is with excellent Different catalytic performance.

Detailed description of the invention

Fig. 1 is the X-ray powder diffraction figure for the Pd@H-PPA that embodiment 1 synthesizes；

Fig. 2 is the Fourier transform infrared spectroscopy figure for the Pd@H-PPA that embodiment 1 synthesizes；

Fig. 3 is the solid-state nuclear magnetic resonance carbon spectrogram for the Pd@H-PPA that embodiment 1 synthesizes；

Fig. 4 is the transmission electron microscope picture for the Pd@H-PPA that embodiment 1 synthesizes；

Fig. 5 is the cycle efficieny figure for the Pd@H-PPA that embodiment 1 synthesizes；

Fig. 6 is that the Pd@H-PPA that embodiment 1 synthesizes participates in the transmission electron microscope picture after 8 catalysis reactions.

Specific embodiment

In order to make content of the present invention easily facilitate understanding, With reference to embodiment to of the present invention Technical solution be described further, but the present invention is not limited only to this.

Embodiment 1

COF-LZU1 is synthesized by known method, COF-LZU1(80 mg) is dispersed in methylene chloride (18 mL) and at ultrasound Reason 20 minutes, then palladium acetate (77.5 mg) is dispersed in 2 mL methylene chloride, then by the dichloromethane solution of palladium acetate It is added in the dichloromethane solution of COF-LZU1, stirs 24 hours, resulting solid is filtered and is washed with methylene chloride more Soxhlet extraction device is put into after secondary, using methylene chloride as cleaning solvent, washing is freeze-dried after 24 hours.By above-mentioned gained Solid (40 mg) is dispersed in tetrahydrofuran and deionized water (20 mL 4:1 v/v), after being stirred and heated to 70 DEG C, is divided small quantities of Repeatedly the investment excessive sodium borohydride solids of 715 mg, continuous heating stir 24 hours amount, and filtering uses tetrahydrofuran and washing It washs and 70 DEG C of dry collect obtains catalyst Pd@H-PPA.

Comparative example 1

COF-LZU1(50 mg) is dispersed in a certain proportion of tetrahydrofuran and the mixed solution of deionized water (4:1 v/v) 70 ^oIt is stirred under C, a small amount of NaBH is added in whipping process₄Continue stirring 12 hours after solid (200 mg).It is collected by filtration and adopts It is washed with tetrahydrofuran and deionized water.Again 100^oIt is dried in vacuo 5 hours under C.Obtained solid (40 mg) is dispersed in 10 mL In methylene chloride, the dichloromethane solution of palladium acetate is added, persistently stirs 12 hours, collect and uses 24 hours use of Soxhlet extraction Methylene chloride washing, 60^oC is dried in vacuum overnight.20 mL tetrahydrofurans are finally dispersed in by solid obtained above (40 mg) With 70 in deionized water mixed liquor^oIt is stirred under C.During churning, NaBH is added₄Continue stirring 24 hours after solid.Finally exist 70 in vacuum^oC is dried overnight to obtain Pd/H-PPA.

The one-step synthesis of use in embodiment 1, synthesis step is simpler, and comparative example 1 is first to synthesize porous polyamine material Material, then go to carry palladium ion and be further reduced into Pd nano particle；But the nanoparticle particle ratio that 1 method of comparative example obtains Larger, average-size is in 4 nm or so, and dispersion is very uneven, and the composite material for causing comparative example 1 to be made, catalytic performance is not It is good.

Using

Synthesized catalyst Pd@H-PPA(20 mg) is dispersed in 9 mL methanol and aqueous mixtures (v/v=4:5) are careful Ground pours into double-neck flask.After stirring mixture is to reach air balance, 1.0 mL are added into flask and contain ammonia borine (1 Mmol aqueous solution)；Pd@H-PPA is changed in the catalytic activity in the dehydrogenation of ammonia borine by the water surface in observation buret, from And the rate of the hydrogen generated is calculated, certain embodiments are completed when water level no longer changes.

Fig. 1 is the X-ray powder diffraction figure of polyalcohol catalyst, and it is that palladium is received that 39.4,45.2,67.3 positions are corresponding in figure Rice corpuscles (111), (200) and (220) crystal face.1320 cm in Fig. 2^-1Locate it is corresponding be secondary amine key characteristic peak, this also complies with figure Also there is the feature peak position of secondary amine key at 47 ppm in the data of 3 solid-state nmrs.It can be understood by transmission electron microscope (Fig. 4) and be seen Nanoparticle (average 2.6 nm) to fine uniform is dispersed in the shell of porous polyamine materials.Pd@is shown in Fig. 5 The high stability of H-PPA catalyst, after 8 circulations, there is no the apparent decreases of generation for reaction rate, after collecting reaction Catalyst is found that serious agglomeration (Fig. 6) does not occur for nanoparticle by transmission electron microscope observing.

Table 1 is the H2-producing capacity of catalyst made from embodiment 1 and comparative example 1

The foregoing is merely representative embodiment of the invention, the modification and change done in all claims according to the present invention Change, all should belong to covering scope of the invention.

Claims

1. a kind of preparation method for the porous polyamine composite material for wrapping up Pd nano particle, it is characterised in that: in COF-LZU1 Palladium acetate solution is introduced, is coordinated by the imine linkage in COF-LZU1 with it, sodium borohydride solids are added and are reduced into divalent palladium Imine linkage in COF-LZU1 is simultaneously reduced into secondary amine key by zeroth order, obtains the more of the tiny high degree of dispersion Pd nano particle of package Hole polyamine composite material Pd@H-PPA.

2. preparation method according to claim 1；It is characterized by comprising following steps:

(2) collected solid is put into a certain proportion of tetrahydrofuran and the mixed solution of deionized water, 70 DEG C of stirrings, And excessive sodium borohydride solids are added thereto and are restored, continuous heating stirs 24 hours,

(3) it filters and is washed with tetrahydrofuran and deionized water, 70 DEG C are dried overnight to obtain and wrap up tiny high degree of dispersion palladium nanometer The porous polyamine composite material Pd@H-PPA of particle.

3. according to the method described in claim 2, it is characterized by: the mass ratio that COF-LZU1 and palladium acetate are added is 1:1.

4. according to the method described in claim 2, it is characterized by: in step (2), the volume ratio of tetrahydrofuran and deionized water For 4:1.

5. according to the method described in claim 2, it is characterized by: obtained Pd nano particle mean size is 2.6 nm sizes It is small, and be highly dispersed in the shell of porous polyamine materials.

6. a kind of application for the porous polyamine composite material for wrapping up Pd nano particle, it is characterised in that: the Pd@H-PPA is urged Agent generates hydrogen for being catalyzed ammonia borine, and reaction temperature is 25 ~ 45 DEG C.