A kind of zsm-5 and zsm-12 composite molecular sieve and its synthetic method

Abstract

The invention provides a ZSM-5 / ZSM-12 composite molecular sieve. The ZSM-5 / ZSM-12 composite molecular sieve has the following two crystal forms at the same time: a ZSM-12 molecular sieve and a ZSM-5 molecular sieve. The synthetic method for the ZSM-5 / ZSM-12 composite molecular sieve provided by the invention comprises the following steps: adding the ZSM-12 molecular sieve into a glucose solution for ultrasonic treatment and carrying out filtering, drying and roasting so as to obtain a treated ZSM-12 molecular sieve; then mixing water, an alkali source, a template agent, an aluminum source and a silicon source and carrying out crystallization so as to prepare pre-crystallized colloid; then mixing the pre-crystallized colloid with the treated ZSM-12 molecular sieve and carrying out crystallization at a temperature of 160 to 220 DEG C for 5 to 25 h so as to obtain the ZSM-5 / ZSM-12 composite molecular sieve. According to the invention, glucose is introduced into the pores of the ZSM-12 molecular sieve and becomes carbon after roasting; the carbon occupies the pore channels of the ZSM-12 molecular sieve to prevent alkali from entering the interior of ZSM-12 molecular sieve crystals, so the ZSM-12 molecular sieve is not destroyed in the process of crystallization and the integrity of crystal structure is maintained, which are beneficial for improvement of the physical and chemical properties and the catalytic activity of the ZSM-5 / ZSM-12 composite molecular sieve.

Description

technical field [0001] The invention belongs to the field of synthesis of molecular sieve catalytic materials, in particular to a ZSM-5 / ZSM-12 composite molecular sieve and a synthesis method thereof. Background technique [0002] Composite molecular sieve is a composite molecular sieve with a special structure, which is a co-crystal formed by two or more molecular sieves, or a composite crystal with the structural characteristics of two or more molecular sieves. Due to the particularity of the composite molecular sieve structure, this molecular sieve has a more reasonable distribution of acidity and good hydrothermal stability, overcomes the limitations of its components, better meets the needs of industrial applications, and has a wide range of applications. Application prospects. [0003] At present, there are many technologies about composite molecular sieves. For example, CN1565967A discloses a method for preparing mordenite / ZSM-5 mixed crystal material. In the method...

AI Technical Summary

Problems solved by technology

[0014] However, there are still many defects and deficiencies in the synthesis technology of composite molecular sieves, which cause some deficiencies in the physical and chemical properties of composite molecular sieves.

For example, the composite structure of composite molecular sieves is not easy to control, and the acid properties are also difficult to adjust.

Moreover, many composite molecular sieves are synthesized by a two-step method, which easily causes damage to the first component during the compounding process, which reduces the physical and chemical properties of the composite molecular sieve, thereby affecting the adsorption and catalytic performance.

Images