Method for preparing nano ZSM-5 molecular sieve

Abstract

The invention discloses a method for preparing a nano ZSM-5 molecular sieve, comprising the steps of preparing a precursor, crystallizing, filtering, drying and roasting. The precursor is prepared by adopting a two-step method; a mixed solution is prepared by adopting a template-free method; a mixed glue solution is prepared by a stirring and dropping method; and the granularity of the molecular sieve obtained by roasting is 50-100 nanometers. In the step of preparing the mixed solution by using the template-free method, NaOH and NaAlO2 in a reactor and deionized water are stirred at the rotating speed of 200-300 / min and the bath temperature of 60-90DEG C for 2-4 hours to obtain the uniformly-mixed solution, wherein the mass ratio of the NaOH to the NaAlO2 to the deionized water is 10:(3-6):(320-380). In the step of preparing the mixed glue solution by the stirring and dropping method, silica sol is slowly dropped in the solution according to the volume ratio while the mixed solution is continuously stirred; the mixed glue solution is obtained after the silica sol is dropped; and the volume ratio of the mixed solution to the silica sol is 200:(115-135).

Description

technical field [0001] The invention relates to a method for preparing nano ZSM-5 molecular sieve. Background technique [0002] In the early 1970s, Mobil Corporation of the United States introduced ammonium salt as a template into the hydrothermal synthesis system of molecular sieves, and first successfully synthesized ZSM-5 molecular sieves. This high-silicon medium-porous zeolite with MFI topology has a unique pore structure and excellent physical and chemical properties because it has no cage. ZSM-5 zeolite is a crystalline silicate catalytic material, which is made into a catalyst and widely used in petroleum refining, petrochemical and fine chemical synthesis. ZSM-5 zeolite has a unique crystal structure and shape-selective catalytic performance, no corrosion, no pollution, and can be recycled and reused. It is an important catalytic material for the development of green chemical processes. The application of ZSM-5 zeolite has penetrated into almost every field of he...

AI Technical Summary

Problems solved by technology

[0014] The organic amines used in the above methods have the disadvantages of high cost and pollution in the production process

The shortcoming of this synthesis method is that the grain size of the molecular sieve is not uniform and the crystallinity is not high, and there will be miscellaneous crystals.