Mordenite and preparation method thereof

Abstract

The invention provides mordenite and a preparation method thereof. The mordenite has an ellipsoidal structural topography formed by stacking a plurality of strip zeolite crystals in the one-dimensional direction in order; and the method for preparing the mordenite with the special structural topography comprises that: a solid silicon-aluminum source raw material is subjected to two-stage crystallization reaction in an extremely thick system, the molar ratio of water to silicon dioxide in the crystallization system is 1-7, the structural topography of the obtained mordenite is obviously difference from that of the conventional product by optimizing and controlling synthesis process and condition parameters, and mesopores and macropores are introduced into the mordenite structure to contribute to solving the problems of dislocation and surface defects of the mordenite structure and better contribute to improving the catalytic performance in xylene isomerization reaction. The invention also provides application of the mordenite with the special structural topography to catalysis in the xylene isomerization reaction.

Description

technical field [0001] The invention relates to the technical field of preparation of zeolite molecular sieves, and in particular provides a mordenite with special structure and morphology and a preparation method thereof. Background technique [0002] About 80% of modern petrochemical processes are related to catalytic processes. The fundamental core technology is the selection and use of catalysts, and the characteristics of catalytic materials themselves are the key to determining their catalytic performance. At present, a consensus has been reached in the field of petroleum processing and catalyst technology that as crude oil becomes increasingly heavy, the conversion of heavy oil macromolecules requires catalysts to provide abundant macropores or even ultra-macropore systems to adapt to the catalytic cracking of larger molecules At the same time, further shape-selective catalysis of catalytic cracking molecules is required, which requires the catalyst to provide a pore ...

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Problems solved by technology

[0009] Chinese patent 200510023802.5 (publication number CN 1673081A) discloses a synthesis method of high-silicon mordenite, which provides a method for preparing high-silicon mordenite in an all-inorganic system by vapor phase spin crystallization (vapor phase transport method, namely VPT) , the method does not use organic templates and fluorides, and the silicon-aluminum ratio of the synthesized mordenite is SiO 2 / Al 2 o 3 =20-40, but the synthesis conditions of this method are harsh and difficult for industrialization

[0016] Throughout various public documents, it can be found that the research on molecular sieve materials including mordenite has attracted great attention in this field. In order to improve the catalytic performance of these molecular sieves, especially mordenite, the focus of research and development is mainly on the composition (such as Si-alumina ratio, skeleton doping modification, etc.), internal pore structure, and grain size, etc., the synthesized grains are basically regular hexahedral crystals or imitation vertical mordenite crystals, while the crystal grains of mordenite There are very few studies on morphology; and the current process of synthesizing mordenite adopts hydrothermal synthesis, and the crystallization raw material is generally a gel mixture with a large water content. Although the hydrothermal crystallization mechanism is beneficial to obtain the desired zeolite product, the production The yield of zeolite in the process is low, and the discharge of mother liquor is large, which is not conducive to environmental protection

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