Synthesis and characterization of [Cr,Al]-ZSM-5 zeolites

被引：26

作者：

Giannetto, G

Garcia, L

Papa, J

Yanez, F

Goldwasser, MR

Linares, C

Moronta, D

Mendez, B

deNavarro, CU

机构：

[1] CENT UNIV VENEZUELA,FAC INGN,ESCUELA INGN QUIM,CARACAS,VENEZUELA

[2] CENT UNIV VENEZUELA,FAC CIENCIAS,CTR CATALISIS PETR & PETROQUIM,CARACAS,VENEZUELA

[3] INTEVEP SA,CARACAS 1070A,VENEZUELA

来源：

ZEOLITES | 1997年 / 19卷 / 2-3期

关键词：

Cr-silicates; Cr; Al-silicates; MFI type zeolites; characterization of zeolites;

D O I：

10.1016/S0144-2449(97)00064-X

中图分类号：

O64 [物理化学（理论化学）、化学物理学];

学科分类号：

070304 ; 081704 ;

摘要：

[Cr-x,Al-y] silicates with MFI-type structure were synthesized from synthesis gels with a Si/(Cr+Al) molar ratio of 23, and compositions of chromium and aluminum varying from 0 to 4. The solids were characterized by chemical analysis, XRD, infrared spectroscopy, magic angle spinning n.m.r., SEM-TEM, N-2 adsorption, and e.s.r. Ail solids were highly crystalline materials. The e.s.r. study shows the presence of Cr(III) in different magnetic environments, depending upon the treatments of the samples. Extensive oxidation of occluded Cr(lll) clusters to Cr(VI) species occurred after calcination, whereas the presence of structural and nonstructural Cr(V) species was also detected. It was observed that the presence of chromium ions in the synthesis gel increases the amount of structural aluminum in the zeolites, which produces [Cr,Al] silicates with acidity and activity in the n-heptane cracking reaction, higher than conventional Al silicates. (C) Elsevier Science Inc. 1997.

引用

页码：169 / 174

页数：6

共 25 条

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