A kind of submicron sapo-5/sapo-18 composite molecular sieve and preparation method thereof

Abstract

The invention discloses a submicron composite molecular sieve for preparing a catalyst for producing low-carbon olefin through organic oxygen compound and a preparation method of the submicron composite molecular sieve. The composite molecular sieve is formed by compounding an SAPO-5 molecular sieve and an SAPO-18 molecular sieve. Raw materials for preparing the composite molecular sieve satisfy the following condition: the molar ratio of SiO2: Al2O3: P2O5 is (0.1-0.6): 1: (0.7-1.3); the addition quantity of the SAPO-5 / SAPO-18 composite sieve screen crystal seed is 1.0 to 5.5 percent by adopting the weight of effective solid content in mixed gel as a benchmark. The SAPO-5 / SAPO-18 composite molecular sieve has submicron-meter granularity and is good in catalytic activity, long in service life and high in qualification molecular sieve yield.

Description

technical field [0001] The invention relates to a submicron SAPO-5 / SAPO-18 composite molecular sieve and a preparation method thereof. Background technique [0002] The catalytic materials used in the methanol-to-olefin reaction are mainly acidic zeolites with small pores and mesopores. In 1982, scientists Wilson ST and Flanigen EM of United Carbon Corporation (UCC) first synthesized a new type of aluminophosphate (ALPO-n) molecular sieve with organic amine as a template in a hydrothermal system. Pore ​​and macroporous AlPO-n series of microporous molecular sieves appeared one after another. [0003] In 1984, Lok et al. first introduced Si into the AlPO-n series of molecular sieves and synthesized a new class of silicoaluminophosphate (SAPO-n) molecular sieves. The pore structure from six-membered ring to twelve-membered ring. Silicoaluminophosphate molecular sieve (SAPO-n) is made of [SiO 4 ], [AlO 4 ] - and [PO 4 ] + Microporous crystals with small pores, mesopores...

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Problems solved by technology

[0015] CN101935049B discloses a silicoaluminophosphate molecular sieve, which is actually a kind of AEI and CHA intergrowth silicoaluminophosphate molecular sieve, such as SAPO-18 and / or ALPO-18 molecular sieve, or SAPO-34 and / or ALPO-34 Molecular sieves are prepared by mixing aluminum sources, phosphorus sources, silicon sources, water, and templates in order to form a gel, and then performing aging and hydrothermal synthesis crystallization in sequence. In the above process, no molecular sieve seeds are used.

[0018] The particle diameters of ALPO-18 and / or SAPO-18 molecular sieves, ALPO-34 and / or SAPO-34 molecular sieves and low-silicon ALPO-5 / ALPO-18 molecular sieves disclosed in the above-mentioned patent documents are all in micron order, that is, their average The particle size is above 1 micron. Therefore, they still need to be improved in terms of total olefin yield and service life as active components of organic oxygen-containing compounds to produce low-carbon olefins.

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