Preparation method of microporous-mesoporous composite zeolite

Abstract

The invention relates to a preparation method of a microporous-mesoporous composite zeolite. The method comprises a step that a Y zeolite precursor commonly used in present heavy oil catalytic cracking is introduced to the pore walls of the composite sieve. The composite sieve has the advantages of high hydrothermal stability, narrow pore size distribution, large mesopore size, short production period, and easily controlled operation conditions, and can be widely applied to the fields of petroleum catalytic cracking, hydrocracking and the like.

Description

technical field [0001] The invention relates to a preparation method of a microporous-mesoporous composite molecular sieve. The product contains a Y-type molecular sieve primary structural unit, a secondary structural unit and two-dimensional hexagonal channels with long-range order and uniformity. It has high hydrothermal stability and narrow The pore size distribution and large mesopore size have very broad application prospects in the fields of petroleum catalytic cracking and hydrocracking. Background technique [0002] Molecular sieves have good shape selectivity and adjustable acid centers, and their regular pore structure can be used to sieve and tailor molecules to achieve shape-selective catalysis, so they are widely used in the field of oil refining catalysis. [0003] Since the 1980s, with the increasingly heavy and inferior quality of crude oil and processing raw materials, secondary crude oil processing methods such as catalytic cracking and hydrocracking are re...

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Problems solved by technology

CN1663912A Put the molecular sieve into the material boat, put the material boat into the furnace tube, process at 500-110°C for 0.5-2h, then fill the furnace tube with ammonia gas, and process at 600-1100°C for 0.5-20h to obtain micro Pore-mesoporous acid-base amphoteric compound molecular sieve, the process has the advantages of simple process, short cycle, and cheap and easy-to-obtain molecular sieve raw materials, but the mesoporous phase of the molecular sieve is distributed between 1.6-3nm, and the pore size is slightly smaller; CN1208718 adopts two steps Crystallization, using a two-way directing agent, first synthesize MCM-41 mesoporous molecular sieves, and then crystallize the amorphous pore walls of the mesoporous molecular sieves to form microporous molecular sieves to obtain Beta / MCM-41 and ZSM-5 / MCM-41 composite molecular sieves, although the The method introduces the primary structural units and secondary structural units of Beta and ZSM-5 into the mesoporous pore wall, but this method does not incorporate the most commonly used Y-type molecular sieves and rare earth phosphorus ZSM-5 molecular sieves in catalytic cracking and hydrocracking catalysts. , Mordenite and other important molecular sieves are introduced into the mesoporous pore wall, which limits his application range; CN101691228A mixes silicon-containing and aluminum-containing components with a strong base in a certain proportion to form a silica-alumina hydrogel. After stirring at 100°C for 12-24h, aging at 20-30°C for 20-24h, then mixing with template agent aqueous solution, and adjusting the pH to 9-10, and then performing the first stage of crystallization at 10-110°C for 48- After mixing the product with water for 90-100 hours at 100-120°C, the product was crystallized for 90-100 hours, then washed and dried to obtain a microporous-mesoporous composite molecular sieve. structure and shows high hydrothermal stability, but the production cycle of this method is too long, and the average pore size (2.5nm) of the synthesized molecular sieve is relatively small; CN102000604A uses kaolin as raw material, and inorganic silicate is a supplementary silicon source to synthesize Y-type molecular sieve Precursor, and then use hexadecyltrimethylammonium bromide as a template agent, under the action of microwaves, a compound molecular sieve with Y / MCM-41 was synthesized, and the material also showed defects with a slightly smaller average pore size (2.7nm) ; CN101863491A Stir the alkali source, silicon source, aluminum source and deionized water evenly, add sodium dodecylbenzenesulfonate, stir at room temperature for 0.5-3h, and crystallize and cultivate L molecular sieve nanocrystals at 100-170°C Then add it to the template solution, adjust the pH to 7.0-11.0, stir at room temperature for 0.5-3h, crystallize at 90-110°C for 24-72h, wash, dry, and roast to obtain L / MCM -41 composite molecular sieve, the defect of this method is that the molecular sieve is synthesized under alkaline conditions, if the synthesis conditions cannot be well controlled, the L molecular sieve directing agent will continue to grow, and finally a mixed phase of L molecular sieve and MCM-41 will be generated , rather than composite molecular sieves (Song Chunmin, Yan Zifeng. New progress in research on microporous-mesoporous composite molecular sieves[J]. Molecular Catalysis. 2008, 22 (3): 280-287)

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