Synthesis and characterization of composite molecular sieves comprising zeolite Beta with MCM-41 structures
- 31 May 2001
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of Materials Chemistry
- Vol. 11 (7) , 1886-1890
- https://doi.org/10.1039/b009903l
Abstract
Zeolite Beta/MCM-41 composites have been prepared with various crystallinities of zeolite Beta through a two-step crystallization process involving the combination of low crystallinity zeolite Beta synthesis gel with cetyltrimethylammonium bromide surfactant solution. The composites are characterized by XRD, SEM, 29Si and 27Al MAS NMR, N2 adsorption, NH3-TPD and catalytic cracking. The experimental results show that the relative crystallinity of Beta in the composites greatly affects the morphology and surface acidity of the materials, while exhibiting similar 29Si, 27Al MAS NMR spectra and N2 adsorption–desorption isotherms. The pore structural data indicate that the composites contain bimodal mesopore systems and microporous structures of zeolite Beta. Although the number of weak acid sites on the composites with various crystallinities of Beta is comparable, composites with higher Beta crystallinity possess more medium acid sites and show higher catalytic activity for n-heptane cracking.Keywords
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