Preparation method of molecular sieve coating material on surface of porous silicon carbide ceramic with surface rich in silicon

Abstract

The invention relates to a preparation method of a molecular sieve coating material on the surface of porous silicon carbide ceramic with the surface rich in silicon, and the molecular sieve coating material is prepared by using the porous silicon carbide ceramic with the surface rich in silicon as a carrier; using solid materials, such as silicon blocks, quartz, sliicon-alumininm composite oxide sintering powder with adjustable sliicon-alumininm atomic ratio, and the like as a silicon source or a sliicon-alumininm source, and adopting a in situ hydrothermally synthesizing method. Molecular sieve crystals preferentially nucleate on the surface of the porous silicon carbide ceramic due to a surface silicon layer of the porous silicon carbide ceramic, the solid silicon source or the sliicon-alumininm source are used so that the release speed of the silicon source or sliicon-alumininm source for the growth of crystal nucleus is controllable. Therefore, prepared molecular sieve coating is uniformly loaded on the surface of the silicon carbide ceramic carrier; the composite material formed by a molecular sieve and the porous silicon carbide ceramic has a unique micropore / macropore structure; chemical combination is realized between the molecular sieve and the porous silicon carbide ceramic, and the molecular sieve and the porous silicon carbide ceramic have high interface combination strength. The preparation method has simple technology, convenient operation without complex equipment and low manufacturing cost and is more suitable for industrialized and mass production.

Description

Technical field [0001] The present invention belongs to the preparation technology of surface silicon-rich porous silicon carbide ceramic surface molecular sieve coating material, and particularly provides a high interface bonding strength and uniform loading surface silicon-rich silicon carbide ceramic surface including pentasil family molecular sieve (including ZSM-5, silicalite -I, β, ZSM-11, silicalite-II and ZSM-12 type molecular sieve, etc.) and mordenite type molecular sieve and other molecular sieve coating materials preparation methods. Background technique [0002] Molecular sieves are crystalline aluminosilicates with uniform crystal structure, which are characterized by many regular pores interconnected by a large number of small rectangular channels. It has been found that due to this structure consisting of a network of interconnected uniform-sized pores and channels, crystalline molecular sieves can absorb molecules with a size lower than a certain appropriate pres...

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) There is a large difference in thermal expansion coefficient between metal and molecular sieve, and the molecular sieve layer will easily 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

However, during the preparation of foamed silicon carbide, the amount of silicon on the surface is not easy to control

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