Sapo-34 hierarchical porous molecular sieve self-assembled in nanosheet spiral shape and preparation method thereof

Abstract

The invention relates to a SAPO-34 multi-level pore molecular sieve with nanosheets that are self-assembled in a vortex shape and a preparation method thereof. The multi-level pore molecular sieve is composed of SAPO-34 molecular sieve nanosheets with controllable thickness arranged in a vortex shape and self-assembled. It has both the micropores of SAPO-34 molecular sieve and the stacked mesopores of SAPO-34 molecular sieve nanosheets. It is prepared by adding organic amine template A and organic amine template B in the hydrothermal synthesis system. It has both SAPO- 34 molecular sieve has micropores and nanosheet-stacked mesopores. By adjusting the nanosheet thickness, the nanosheet-stacked mesopore diameter can be adjusted, thereby realizing the adjustable SAPO-34 molecular sieve. Moreover, the catalyst of the present invention has good catalytic performance. The MTO reaction can improve the selectivity of olefins and extend the service life of the catalyst. The synthesis process is simple, the product is easy to collect, and no centrifugal separation is required. It greatly simplifies the process conditions and is conducive to industrial large-scale production.

Description

technical field [0001] The invention belongs to the technical field of molecular sieve research, and in particular relates to a SAPO-34 multi-stage molecular sieve self-assembled in a spiral shape of nanosheets and a preparation method thereof. Background technique [0002] The characteristics of my country's energy structure determine that for a long period of time in the future, coal will still be the main body of my country's energy consumption, but the traditional method of using coal energy will bring great pollution, so the efficient and clean transformation and utilization of coal has become the focus , among which the coal-to-methanol process is one of the key points for efficient and clean conversion and utilization of coal. According to statistics, as of 2015, my country's annual methanol production has reached 60 million tons, but the annual consumption does not exceed 40 million tons, which has caused serious overcapacity, so new processes are needed to convert an...

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Problems solved by technology

Studies have shown that: SAPO-34 molecular sieves or hierarchically porous SAPO-34 molecular sieve catalysts prepared with small crystals (nanometer size) have good olefin selectivity and longer catalytic life for MTO reactions (CN102618610A, [Qiming Sun, Ning Wang , Dongyang Xi, Miao Yang and Jihong Yu*.Organosilane surfant-directed synthesis of hierarchical porous SAPO-34catalysts with excellent MTOperformance.Chem.Commun.2014,50,6502-6505.]), however, small crystals or nano-sized SAPO-34 requires external conditions such as ultrasonic waves, which limits its industrial application, and there are problems such as the difficulty in separating the nano-sized molecular sieve crystals obtained after synthesis; multi-level porous SAPO-34 molecular sieves often rely on organic materials with extremely complex molecular structures. Synthesis of structure-directing agents as templates〔Xiaochun Zhu, Jan P.Hofmann, Brahim Mezari, Nikolay Kosinov, Leilei Wu, Qingyun Qian, Bert M.Weckhuysen, Shunsuke Asahina, Javier Ruiz-Martínez, and Emiel J.M.Hensen*.Trimodal Porous Hierarchical SSZ- 13Zeolite with Improved Catalytic Performance in the Methanol-to-OlefinsReaction.ACS catalysis.2016,6,2163-2177.], development and application costs are high

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