Method for synthesizing kaolin microsphere in-situ crystallized product containing small crystal grain NaY molecular sieves

Abstract

The invention relates to a method for synthesizing a kaolin microsphere in-situ crystallized product containing small crystal grain NaY molecular sieves. Kaolin is used as a raw material. The method comprises the following steps of: adding deionized water and sodium silicate or sodium pyrophosphate into the kaolin, mixing and slurrying, performing spray drying on the mixed slurry to prepare kaolin spray microspheres with particle diameters of 20 to 110 microns, roasting a part of the kaolin spray microspheres for 1 to 3 hours at the temperature of between 920 and 1,000 DEG C to obtain high-temperature roasted microspheres, and roasting the other part of the kaolin spray microspheres for 1 to 3 hours at the temperature of between 700 and 900 DEG C to obtain metakaolin microspheres; mixing the high-temperature roasted microspheres and the metakaolin microspheres in a mass ratio of 9:1-1:9, adding sodium silicate, directing agent, sodium hydroxide solution, deionized water and organic additive into the mixture, and crystallizing for 16 to 36 hours at the temperature of between 90 and 95 DEG C; and filtering, removing mother solution, and drying the filtrate to obtain the kaolin microsphere in-situ crystallized product containing NaY molecular sieve crystal grains of 200 to 400 nanometers.

Description

technical field [0001] The invention relates to a method for using kaolin spray microspheres as raw materials and in-situ crystallization to synthesize a kaolin microsphere in-situ crystallization product containing crystal grains of NaY molecular sieves with small crystal grains of 200-400nm. The in-situ crystallization of kaolin microspheres synthesized by this method can be used as the precursor for the preparation of catalytic cracking catalysts. Background technique [0002] NaY molecular sieve is the most important active component of fluid catalytic cracking (FCC) catalyst, its performance directly affects the reaction result of catalytic cracking, and has an important impact on the economic benefit of catalytic cracking unit. The purpose of catalytic cracking reaction is the process of producing gasoline, diesel, liquefied petroleum gas and other small molecular products through catalytic reaction of heavy raw materials with large molecules. [0003] With the reduct...

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Problems solved by technology

Studies have shown (Shen Shimin, Synthesis and properties of submicron NaY molecular sieves, Qilu Petrochemical Industry, 2002, 30(1): 6-9), due to the harsh reaction conditions of FCC, when the gel method synthesizes NaY molecular sieves, the grain size decreases. When it is below 500nm, its stability drops rapidly, and it can no longer meet the requirements of FCC catalysts for the stability of NaY molecular sieves, so that the application of small-grain NaY molecular sieves prepared in the prior art in catalytic cracking catalysts is limited.

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