Method for preparing SSZ-39 molecular sieve by taking fluorine-modified Y-type molecular sieve as raw material

Abstract

The invention discloses a method for preparing an SSZ-39 molecular sieve by taking a fluorine-modified Y-type molecular sieve as a raw material. The method comprises the following steps: dipping a Y-type molecular sieve in a fluorine-containing aqueous solution, and drying and roasting the Y-type molecular sieve to obtain a fluorine-doped Y-type molecular sieve; mixing and stirring deionized water, an alkali source, a template agent and a silicon source well in proportion, and adding the fluorine-doped Y-type molecular sieve to prepare sol; and transferring the sol into a crystallization kettle, filtering, washing and drying the crystallization product after complete crystallization, carrying out ion exchange, and carrying out roasting to obtain a hydrogen type SSZ-39 molecular sieve. According to the invention, the Y-type molecular sieve raw material is modified by a fluorine doping method, so that the SSZ-39 molecular sieve can be prepared by complete crystal transformation in a short time under the condition of relatively low silica-alumina ratio, and the raw material and production costs can be obviously reduced. The SSZ-39 molecular sieve prepared by the method has the characteristics of short crystallization time, high crystallinity, controllable grain size, good grain dispersity and the like, and can be applied to the fields of methanol-to-olefin reaction, carriers of selective catalytic reduction catalysts and the like.

Description

technical field [0001] The invention relates to a method for preparing SSZ-39 molecular sieve by using fluorine-modified Y-type molecular sieve as a raw material, in particular to using fluorine-modified Y-type molecular sieve as all aluminum source and part or all silicon source, and preparing silicon A method for preparing SSZ-39 molecular sieves after crystallization reaction of aluminum sol. The invention also relates to the application of the SSZ-39 molecular sieve as a methanol-to-olefin (MTO) catalyst and a selective catalytic reduction (SCR) catalyst carrier. Background technique [0002] Zones et al. synthesized SSZ-39 aluminosilicate molecular sieve for the first time in 1999. The molar ratio of silicon dioxide and aluminum oxide (silicon-aluminum ratio) is between 10 and 100. The skeleton topology of the molecular sieve is AEI. The basic structural units of double six-membered rings (D6R) are linked by some four-membered rings to form a three-dimensional channel ...

AI Technical Summary

Problems solved by technology

The most researched and applied molecular sieves are Y-type molecular sieves, mainly hydrogen-type and ammonium-type, and the silicon-aluminum ratio is usually above 10, such as CBV712 and CBV720 of Zeolyst Company. The higher the silicon-aluminum ratio of Y-type molecular sieves, the corresponding preparation process The more complex, the higher the production cost

However, the control indicators such as the silicon-aluminum ratio and crystallinity of the existing commercial Y molecular sieves are mainly designed for the application fields such as catalytic cracking catalysts. For the application of crystal conversion to prepare SSZ-39 molecular sieves, the control indicators may not be applicable. At the same time Its quality will also directly affect the quality of SSZ-39 molecular sieve, resulting in many uncertain factors in the scale-up production of SSZ-39 molecular sieve

[0006] In summary, in many patent documents, there are relatively few studies on the preparation of SSZ-39 molecular sieve by heteroatom-doped modified Y-type molecular sieve through crystallization

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