2014-Sustainable Industrial Processing Summit
SIPS 2014 Volume 5: Composite, Ceramic, Quasi-crystals, Nanomaterials & Coatings
| Editors: | Kongoli F |
| Publisher: | Flogen Star OUTREACH |
| Publication Year: | 2014 |
| Pages: | 578 pages |
| ISBN: | 978-1-987820-07-2 |
| ISSN: | 2291-1227 (Metals and Materials Processing in a Clean Environment Series) |
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Crystallization process of the faujasite zeolite: effect of alumina and silica sources
Adriana Medina Ramirez1;1UNIVERSITY OF LA CIENEGA, Sahuayo de Morelos, Mexico;
Type of Paper: Regular
Id Paper: 293
Topic: 16
Abstract:
Two different alumina and silica sources were used to synthesize faujasite zeolite by hydrothermal treatment. In the conventional synthesis (CS), sodium aluminate and sodium silicate were used. A gel was prepared using NaOH and the crystallization was carried out at 90°C for different periods of time. A second synthesis (RS) was performed using a raw material called fly ash; it was mixed with NaOH and submitted to heat treatment at 600°C, for 2 h. Subsequently, it was submitted at ageing step and then crystallization was performed at 90°C. Samples were collected at different periods of time and they were characterized by XRD, SEM, XRF and FT-IR. The results for CS synthesis indicated the amorphous phase persists after 4h of crystallization. The faujasite zeolite appeared after six hours, and the crystalline phase after 8 h. For RS synthesis silicate and aluminate species were detected after the heat treatment. After two hours of crystallization, the P zeolite was formed, the faujasite zeolite was detected after 6 h together to P zeolite; eight hours later the faujasite zeolite was the unique crystalline phase. This behavior indicated the metastability of zeolites. P zeolite goes through a dissolution process led to a rearrangement in T-O bonds, generating a different structure, the faujasite. Variation in the contents of Si, Al and Na were observed in the samples of the two synthesis routes. Evidences of building structure units (BSU) of zeolite were found by FT-IR. For RS synthesis, single and double rings were formed during the first 4 hours of crystallization corresponding to BSU of P zeolite structure, while vibrations of the double 6-members rings were observed after 6 h, en both CS and RS synthesis. These results showed the nature of silica and alumina sources is a crucial parameter in the zeolites crystallization process.