Method for preparing rare earth-containing MCM-49 molecular sieve

Abstract

The invention provides a method for preparing an MCM-49 molecular sieve containing rare earth. The molecular sieve comprises the following raw materials: an aluminum source, a base source, a silicon source, hexamethylene imine, cyclohexane, deionized water and salts of the rare earth, wherein the molar ratios of the raw materials comprise: SiO2:Al2O3 is 12-50, OH:SiO2 is 0.05-0.7, (HMI+CHA):SiO2 is 0.08-1.2, H2O:SiO2 is 10-70, and Re2O3:Al2O3 is 0.01- 0.5. The method comprises the following steps: putting the raw materials into a synthesizing kettle according to the ratios, and sealing the kettle; raising programming temperature to a crystallization temperature of between 135 and 180 DEG C; and then crystallizing and cooling the raw materials in self-generated pressure; and obtaining the MCM-49 molecular sieve containing the rare earth after a crystallized product is subjected to filtering, washing and drying. The method can improve the stability of a molecular sieve catalyst by introducing the rare earth into the molecular sieve in synthesizing, and obviously reduce the synthesizing cost by replacing partial or most of the hexamethylene imine by the cyclohexane in organic amine; meanwhile, the preparation method has the characteristics of good repeatability and high degree of crystallinity of the product.

Description

technical field [0001] The invention relates to a preparation method of rare earth-containing MCM-49 molecular sieve. Background technique [0002] MCM-49 molecular sieve is a molecular sieve first developed by Mobil Corporation (USP5,236,575), which has a MWW structure configuration. In the field of heterogeneous catalysis, MCM-49 molecular sieve can be used in various reaction processes including aromatization, isomerization and disproportionation, and has a good application prospect. [0003] At present, the template agent for synthesizing MCM-49 zeolite is basically hexamethyleneimine (HMI), although USP5,236,575 mentions in its claims that organic amines for synthesizing MCM-49 include cycloalkylamine (cycloalkylamine) The Chinese patent application number 02145238.5 also mentions that cycloheptaneamine, cyclohexaneamine and cyclopentaneamine can be used as templates for the synthesis of MCM-49, but there is no relevant experimental data. In fact, at present, it is di...

AI Technical Summary

Problems solved by technology

Generally by the traditional ion exchange method, the Re 3+ Ions are exchanged into the pores of molecular sieves, but due to the large radius of hydrated ions, the exchange is difficult, and the uniformity of the exchanged products is not ideal. In order to improve this defect, salts containing rare earth elements can be added to the synthetic raw materials of molecular sieves. Make rare earth elements enter molecular sieves during crystallization