Preparation method and application of core-shell catalyst which adopts transition metal salt as core and nano-molecular sieve as shell

Abstract

The invention relates to a preparation method and application of a core-shell catalyst which adopts a transition metal salt as a core and a nano-molecular sieve as a shell, and belongs to the technical field of catalysts. The preparation method comprises the steps of: firstly preparing transition metal oxide or transition metal hydroxide, performing surface modification on the oxide and hydroxideof transition metal by using a polyelectrolyte so as to make the surface of the oxide and hydroxide of the transition metal positively or negatively charged, coating the surface of the modified oxideand hydroxide of the transition metal with a layer of silicallite-1 type nano-molecular sieve seed crystals by using an electrostatic layer-by-layer self-assembly method, then performing secondary growth of a silicallite-1 type molecular sieve membrane on the silicallite-1 type nano-molecular sieve seed crystals so as to obtain a solid B which adopts the transition metal oxide or transition metalhydroxide as the core and the silicallite-1 type molecular sieve as a shell, performing a solid-phase reaction between with the solid B and ammonium salt solid powder so as to obtain Malpha(NH3)nXbeta@silicallite-1, Malpha(NH3)nXbeta@silicallite-1, and performing low temperature calcination to obtain the core-shell catalyst MalphaXbeat@silicallite-1. Through the core-shell catalyst MalphaXbeat@silicallite-1, synthesis of organic carbonates can be catalyzed.

Description

Technical field [0001] The invention relates to a preparation method and application of a core-shell catalyst with a transition metal salt as a core nano molecular sieve as a shell, and belongs to the technical field of catalysts. Background technique [0002] Dimethyl Carbonate (DMC), ethyl methyl carbonate, diethyl carbonate, diphenyl carbonate (DPC), ethylene carbonate, propylene carbonate, etc. are typical representatives of organic carbonates. The most widely used are dimethyl carbonate and diphenyl carbonate. Among them, dimethyl carbonate is an important chemical intermediate and solvent. Its molecular structure contains reactive groups such as methyl, methoxy, and carbonyl. It has various reaction properties and is widely used in the synthesis of medicines, pesticides, and engineering. Dozens of fine chemicals such as plastic polycarbonate and perfume intermediates have very good market prospects and economic benefits. Diphenyl carbonate is mainly used to synthesize che...

AI Technical Summary

Problems solved by technology

At present, the transesterification method is mainly based on the reaction method of dimethyl carbonate and phenol as raw materials under the catalyst. This synthetic method is "green" and has low investment, but its obvious disadvantage is that it is difficult to break the restriction of thermodynamic equilibrium and make the reaction equilibrium shift to the right Mobile, by-product methanol and dimethyl carbonate form an azeotrope, which is difficult to separate

[0003] At present, there is no catalyst that can break the thermodynamic limit in the catalytic synthesis of organic carbonates and shift the equilibrium to the right to increase the yield of dimethyl carbonate and diphenyl carbonate

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