Synthesis method for ZSM-11 molecular sieve with nano multi-stage pores

Abstract

The invention discloses a synthesis method for a ZSM-11 molecular sieve with nano multi-stage pores. The synthesis method comprises the following steps of (1) carrying out acid treatment on calcined kaolin to obtain modified kaolin; (2) mixing the modified kaolin with an additional silicon source, an organic template agent, inorganic base, alcohol and water and stirring uniformly; (3) drying slurry prepared in the step (2) to form xerogel; and (4) crystallizing the xerogel under the assistance of water vapor, calcining crystallization products obtained at high temperature to obtain the ZSM-11 molecular sieve. The synthesis method disclosed by the invention has the advantages that the ZSM-11 molecular sieve with the nano multi-stage pores is high in degree of crystallinity, small in grain and good in hydrothermal stability, and has large specific surface area and rich microporous and mesoporous channels; simultaneously, the synthesis cost of the ZSM-11 molecular sieve is greatly reduced, and a product does not need to be filtered, so that the environment-friendly effect in the synthesis process is obviously improved.

Description

technical field [0001] The invention belongs to the field of synthesis of molecular sieves, and in particular relates to a synthesis method of nanometer hierarchical porous ZSM-11 molecular sieves. Background technique [0002] ZSM-11 molecular sieve is a new structure molecular sieve first developed by Mobil in the early 1970s. ZSM-11 belongs to the MEL structure configuration and belongs to the Pentasil type molecular sieve, which has a very unique lattice structure, and the ratio of silicon to aluminum in the crystal structure is high. The surface of its crystal has obvious hydrophobic effect and strong surface acidity. It is an important adsorbent and a good shape-selective catalyst. It has excellent performance in heavy oil catalytic cracking, methanol conversion to gasoline, hydrocracking and catalytic dewaxing reactions. catalytic performance. [0003] In recent years, the research on the catalytic performance of ZSM-11 molecular sieve has become increasingly active...

AI Technical Summary

Problems solved by technology

[0006] (1) Most of the synthetic raw materials use expensive chemical reagents, which greatly increases the synthesis cost of ZSM-11 molecular sieve, which is not conducive to large-scale industrial application

[0007] (2) The post-treatment of hydrothermal synthesis needs to be filtered, and the crystallization product can only be obtained after the crystallization wastewater is filtered out, resulting in a large amount of wastewater pollution

[0008] (3) The preparation of nano-hierarchical ZSM-11 is not only cumbersome, but the yield is low, and it is necessary to add a mesoporous directing agent, which greatly increases the synthesis cost

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