Method for preparing palladium catalytic materials supported by chitosan-modified montmorillonite

Abstract

The invention relates to a method for preparing palladium catalytic materials supported by chitosan-modified montmorillonite. The palladium catalytic materials are used for catalyzing organic reaction. The method has the advantages that chitosan can be fed into spaces among layers of cationic montmorillonite in acid solution by the aid of ion exchange processes, accordingly, spacing of the layers of the montmorillonite can be enlarged, transition metal can be supported by means of sufficient complexation on the dropwise added transition metal and the chitosan, and the palladium catalytic materials supported by the chitosan-intercalated montmorillonite can be obtained by means of centrifuging, washing and drying and are excellent in comprehensive performance; the specific surface areas of the palladium catalytic materials are enlarged by 10-20 times as compared with original montmorillonite, and the palladium catalytic materials are high in heat stability and mechanical stability and are excellent in catalytic activity and reuse stability when applied to organic coupling reaction.

Description

technical field [0001] The invention relates to a preparation method of chitosan-modified montmorillonite-loaded palladium catalytic material for organic reaction heterogeneous catalysis, and belongs to the technical field of chemical catalyst preparation technology. Background technique [0002] Both chitosan and montmorillonite clay are natural materials with abundant reserves in nature. Both of them have the characteristics of some excellent supports for transition metal catalysts, and are typical representatives of polymer supports and inorganic supports for transition metal catalysts. Chitosan has a large number of polar groups such as amino and hydroxyl groups in the molecular structure, which can form a strong complex with transition metal palladium plasma; montmorillonite has a unique layered structure, strong adsorption and cation exchange properties , and high thermal stability and mechanical strength. However, when chitosan and montmorillonite are used as a singl...

AI Technical Summary

Problems solved by technology

However, when chitosan and montmorillonite are used as a single catalyst material carrier, they also have some shortcomings of their own.

When chitosan is used as a catalytic material carrier, it has small specific surface area, poor heat resistance, and is easily damaged after repeated use, resulting in the loss of transition metals, etc.

Taking chitosan-supported palladium heterogeneous catalytic materials for Heck coupling reaction as an example, most catalysts can only be reused 6-10 times (Bradshaw, M.; Zou, J.L.; Byrne, L.; Iyer, K.S.; Stewart, S.G.; Raston, C.L.Chem.Commun.2011, 47, 12292-12294), the main reason is that polymer materials are prone to aging and degradation in the use of organic solvents at high temperatures (reaction temperatures generally exceed 100°C) for a long time , the transition metals lose faster through the defects formed by the aging of the material

When montmorillonite is used as a catalytic carrier, the complexation between montmorillonite and transition metals is weak, and the heterogeneous catalytic material made of directly supporting transition metals loses transition metals too quickly during repeated use, resulting in poor reusability. (Dutta, D.; Dutta, D.K. Appl. Catal. A: Gen. 2014, 487, 158-164)

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