A kind of graphene supported palladium catalyst and its preparation method and application

Abstract

The invention discloses a graphene-supported palladium catalyst, the raw materials of which include by volume: 2-10 parts of material A, 30-50 parts of ethylene glycol, 100-150 parts of graphene, and 5-20 parts of KTiNbO5 nanosheet solution; Wherein, the raw material of A material comprises PdCl2 and concentration is 30-37% hydrochloric acid, PdCl2 and hydrochloric acid weight volume ratio g:ml is 0.01-0.1:10-40; The present invention also discloses the preparation of a kind of graphene supported palladium catalyst Method; the present invention also discloses the application of a graphene-supported palladium catalyst; the graphene-supported palladium catalyst of the present invention changes the traditional synthesis method, does not need to add a surfactant, the particle size of the material is small, and the operation is simple, and can be applied to the production of cinnamic acid During the synthesis process, the yield of cinnamic acid is high, the preparation process is easy to separate, the post-treatment is simple, and the reaction conditions are mild, green and economical.

Description

technical field [0001] The invention relates to the technical field of graphene-supported palladium catalysts, in particular to a graphene-supported palladium catalyst and its preparation method and application. Background technique [0002] Heck discovered the Heck reaction in 1972. Since the end of the 20th century, the Heck reaction has gradually developed into an increasingly widely used organic synthesis method. After entering the 20th century, the Heck reaction has been a research hotspot in catalytic chemistry and organic chemistry. The Heck reactants are mainly halogenated aromatic hydrocarbons (mainly iodine) reacting with alkenes containing α-electron-withdrawing groups catalyzed by Pd(0), Pd(II) or Pd-containing complex catalysts to generate aromatic alkenes. The reaction undergoes five steps: oxidative addition of Pd, coordination of Pd and double bonds, cis-coplanar insertion, cis-coplanar β-H elimination, and reductive elimination. In the reaction, Pd(0) was ...

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Problems solved by technology

[0005] The traditional method uses NaBH 4 or LiAlH 4 Make Pd 2+ When reducing to Pd, a surfactant needs to be added, and the added reducing agent is not easy to disperse evenly in the solution. During the reduction, the metal often agglomerates, and the prepared catalyst has a large particle size.

[0006] In addition, at present, the industry mainly utilizes the Perkin reaction to synthesize cinnamic acid. Its disadvantages are low activity of acetic anhydride, high reaction temperature (140-180 ° C), low yield (38-45%), etc., which are not conducive to industrial production. The laboratory uses benzaldehyde and malonic acid as raw materials to synthesize cinnamic acid through Knoevenagel condensation reaction, and reflux reaction at 90°C for 1.5h. The yield of cinnamic acid can reach 96.28%, but the above methods all use benzaldehyde as raw material, so In order to prevent the polymerization between benzaldehyde, not only need to add a polymerization inhibitor (such as 4-tert-butylcatechol), and benzaldehyde is easily oxidized to benzoic acid, so it is difficult to separate from the product cinnamic acid, and post-reaction treatment requires water Steam distillation, activated carbon decolorization time-consuming and labor-intensive process

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