Method for confinement preparation of high-dispersion palladium sub-nanometer particles through zeolitic imidazolate frameworks (ZIFs)

A technology of zeolite imidazolate and framework materials, which is applied in the field of synthesis of highly dispersed sub-nanometer particles, which can solve the problems of difficult diffusion and adsorption of metal salts and reducing agents, and achieve the effects of uniform size, regular shape and good stability

Inactive Publication Date: 2019-11-08
SOUTHEAST UNIV
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Problems solved by technology

Moreover, metal salts and reducing agents are difficult to diffuse and adsorb in the nanopores of MOFs, resulting in the aggregation of synthesized nanoparticles on th

Method used

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  • Method for confinement preparation of high-dispersion palladium sub-nanometer particles through zeolitic imidazolate frameworks (ZIFs)
  • Method for confinement preparation of high-dispersion palladium sub-nanometer particles through zeolitic imidazolate frameworks (ZIFs)
  • Method for confinement preparation of high-dispersion palladium sub-nanometer particles through zeolitic imidazolate frameworks (ZIFs)

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preparation example Construction

[0025] The present invention provides a method for preparing high-content, highly dispersed palladium subnano-scale particles using zeolite-like imidazolate framework materials, comprising the following steps:

[0026] 1) ZIFs were prepared according to the prior art, that is, metal nitrate and imidazole derivatives were respectively dispersed in 50 mL of methanol, the metal nitrate solution was poured into the imidazole derivative solution, and stirred at 600 rpm for 2 h at room temperature. Centrifuge at 15,000 rpm for three minutes, wash with methanol three times, and dry under vacuum at 80°C for 24 hours.

[0027] 2) Pre-mix the ZIFs dispersion with the palladium salt solution under reduced pressure, stir the reaction, filter with suction, and dry to obtain Pd 2+ / ZIFs.

[0028] The palladium salt precursor is sodium tetrachloropalladate; the mass ratio of palladium salt and carrier ZIFs is 1:15~10:15; the solvent for dispersing ZIFs and sodium tetrachloropalladate is ult...

example 1

[0035] (1) Preparation of carrier ZIF-8

[0036] Disperse 2.453g of zinc nitrate hexahydrate and 5.4186g of 2-methylimidazole in 50mL of methanol respectively, pour the zinc nitrate hexahydrate solution into the 2-methylimidazole solution, and stir at 600rpm for 2h at room temperature. Centrifuge at 15,000 rpm for three minutes, wash with methanol three times, and dry under vacuum at 80°C for 24 hours.

[0037] (2)Pd 2+ / Preparation of ZIF-8

[0038] The mass ratio of sodium tetrachloropalladate and carrier ZIF-8 is 1:15, which are respectively dispersed in ultrapure water with a volume ratio of 1:2, and the mixed solution is vacuumized for 10min, stirred for 2h under 1000rpm rotating speed, suction filtered, and filtered with an ultrapure water Wash with pure water three times or more, and vacuum dry at room temperature for 20 minutes.

[0039] (3) Preparation of Pd@ZIF-8

[0040] Disperse Pd with 20 mL of ultrapure water 2+ / ZIF-8, add 3.43mL of sodium borohydride with...

example 2

[0043] (1) Preparation of carrier ZIF-67

[0044] Disperse 2.402 g of cobalt nitrate hexahydrate and 5.4186 g of 2-methylimidazole in 50 ml of methanol respectively, pour the cobalt nitrate hexahydrate solution into the 2-methylimidazole solution, and stir at 600 rpm for 2 hours at room temperature. Centrifuge at 15,000 rpm for three minutes, wash with methanol three times, and dry under vacuum at 80°C for 24 hours.

[0045] (2)Pd 2+ / Preparation of ZIF-67

[0046] The mass ratio of sodium tetrachloropalladate to the carrier ZIF-67 is 6:15, respectively dispersed in ultrapure water with a volume ratio of 1:2, vacuumized for 10 minutes for pre-mixing under reduced pressure, stirred at 1000rpm for 2 hours, and filtered , washed with ultrapure water three times or more, and dried in vacuum at room temperature for 20 min.

[0047] (3) Preparation of Pd@ZIF-67

[0048] Disperse Pd with 20 mL of ultrapure water 2+ / ZIF-67, add 20.58mL of sodium borohydride with a concentration...

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Abstract

The invention discloses a method for confinement preparation of high-dispersion palladium sub-nanometer particles through zeolitic imidazolate frameworks (ZIFs). The method comprises the following technological steps that (1) metal nitrate and imidazole derivatives are ultrasonically dispersed in methyl alcohol, and then direct mixing, stirring, centrifugal separation, washing, ultrasonic dispersion and vacuum drying are conducted to obtain the ZIFs; (2) in ZIFs dispersion liquid, a pecursor solution of palladium chloride is added, and then decompression premixing, suction filtration, washingand vacuum drying are conducted to obtain Pd<2+>/ZIFs; and (3) in Pd<2+>/ZIFs dispersion liquid, decompression premixing is conducted, then a reduction agent, namely sodium borohydride, is added for reaction, and then suction filtration, washing and vacuum drying are conducted to prepare the ZIFs confinement loaded high-content and high-dispersion palladium sub-nanometer particles. The preparationmethod is simple, low in cost and environmentally friendly, and the prepared palladium sub-nanometer particles are even in size, good in dispersion and good in thermal stability, and can stably existin an organic solvent system and a water system.

Description

technical field [0001] The invention provides a synthesis method for confining highly dispersed sub-nano particles by using zeolite-like imidazolate framework materials. Background technique [0002] Metal palladium is widely used in the field of organic catalysis and electrocatalysis, but its catalytic properties are largely determined by the particle size and shape of metal palladium catalysts. When the palladium particle size is reduced to the nanometer or even smaller sub-nanometer level, the proportion of atoms on the surface of the particle relative to the atoms inside the particle is extremely high. At this time, the palladium particles have surface geometric effects, electronic characteristics and quantum size effects, which can reduce the activation energy barrier of its catalytic reaction and improve its catalytic activity. However, these small-sized (especially sub-nanometer) palladium particles have a large specific surface energy, which makes them less stable, ...

Claims

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Application Information

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IPC IPC(8): B01J31/28B01J35/10
CPCB01J31/28B01J35/006B01J35/0066B01J35/10B01J35/1004
Inventor 李颖包敏刘松琴
Owner SOUTHEAST UNIV
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