Preparation method for molecular sieve coating material on porous silicon carbide ceramic surface

Abstract

The invention relates to a preparation technique for a molecular sieve coating material, in particular to a preparation method for a molecular sieve coating material on a porous silicon carbide ceramic surface. Porous silicon carbide ceramic is used as a carrier, solid raw materials such as silicon blocks, quartz, silicon-aluminum composite oxide sintered powder with adjustable silicon-aluminum atomic ratio and the like are used as a silicon source or a silicon-aluminum source, and the raw materials are synthesized through in-situ hydrothermal reaction. The porous silicon carbide ceramic surface is provided with microporous structures. The use of the solid silicon source or silicon-aluminum source can enable the release speed of the silicon source or silicon-aluminum source for the growth of crystal nucleus to be controllable. Thereby, the prepared molecular sieve coating is evenly loaded on the surface of the silicon carbide ceramic carrier, the silicon-to-aluminum ratio can be accurately controlled, and the composite material formed by the molecular sieve and the porous silicon carbide ceramic has unique microporous / macroporous structures; and the chemical bonding between the molecular sieve and the porous silicon carbide ceramic is realized and the interfacial bonding strength is high. The invention has the advantages that the technology of the method is simple, the operation is convenient, the complex equipment is not required, the preparation cost is low and the method is more suitable for industrialized mass production.

Description

technical field [0001] The invention belongs to the preparation technology of molecular sieve coating materials on the surface of porous silicon carbide ceramics, and in particular provides a silicon carbide ceramic surface with high interface bonding strength, uniform loading and precise control of silicon-aluminum ratio, including pentasil family molecular sieves (including ZSM-5, Silicalite-I, β, ZSM-11, silicalite-II and ZSM-12 molecular sieves, etc.) and mordenite molecular sieves and other molecular sieve coating materials. Background technique [0002] Molecular sieves are crystalline aluminosilicates with a uniform crystal structure, characterized by many regular pores interconnected by a large number of small rectangular channels. It has been found that, due to their structure consisting of a network of interconnected pores and channels of uniform size, crystalline molecular sieves are able to absorb molecules of a size below some suitably specified value, while rej...

AI Technical Summary

Problems solved by technology

The use of metal as a carrier brings the following problems: 1) Since metal has a catalytic effect on many chemical reactions, while increasing unnecessary side reactions, it also makes the metal substrate susceptible to deep oxidation

2) The thermal expansion coefficient difference between the metal and the molecular sieve is large, and the molecular sieve coating is likely to fall off when the temperature changes suddenly

4) Due to the high intrinsic density of the metal, the metal carrier accounts for too much in the entire catalyst

At the same time, in the process of preparing aluminum-silicon molecular sieves, due to the existence of surface silicon, the silicon-aluminum ratio of the prepared molecular sieve coating is difficult to accurately control.

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