Published

2016-01-01

Improvements in the synthesis of zeolites with low Si/Al ratio from Venezuelan sodium silicate for an environmentally friendly process

Mejoras en la síntesis de zeolitas con baja relación Si/Al partir de un silicato de sodio de Venezuela para un proceso ambientalmente amigable.

Keywords:

LTA zeolites, FAU zeolites, hydrothermal synthesis, zeolite synthesis, environmentally friendly process. (en)
Zeolita LTA, zeolita FAU, síntesis hidrotérmica, síntesis de zeolitas, proceso ambientalmente amigable. (es)

Downloads

Authors

  • Adriana Lucía García Aggregate Professor, Escuela de Ingeniería Química UCV, Venezuela.
  • Carmen Milena López Titular Professor, Escuela de Química, UCV, Venezuela
  • Luis Vicente García Professor, Universidad Técnica Particular de Loja, Ecuador
  • Mireya Rincón de Goldwasser Titular Professor, Escuela de Química, UCV, Venezuela
  • Johliny Del Carmen Casanova Assistant Professor, Escuela de Ingeniería Química UCV, Venezuela

LTA and FAU zeolites were successfully synthesized from a Venezuelan sodium silicate solution, by hydrothermal crystallization under autogenous pressure at 100°C, with 2–24h crystallization times. The synthesized materials were characterized by XRD, BET specific surface area and SEM. A series of synthesis tests were performed to study the influence of the molar composition of the starting mixture over zeolites crystallization. The effect of crystallization time for a particular synthesis mixture composition was studied for both zeolites types. The reuse as alkaline medium of the mother liquor separated during filtration, and the effect of the aging before crystallization were additionally studied. The experimental result  are in agreement with the crystallization mechanism proposed for zeolites synthesis in liquid phase. The use of a 2SiO2:Al2O3:6.Na2O:240H2O synthesis mixture composition allows obtaining LTA zeolite within 2h of crystallization. For FAU zeolite, no aging period was needed when starting with a 4SiO2:Al2O3:6.6Na2O:264H2O composition. It was possible to synthesize both zeolites with high purity and crystallinity and with adequate water adsorption properties.

Zeolitas LTA y FAU fueron sintetizadas con éxito a partir de una solución de silicato de sodio venezolano, por cristalización hidrotérmica bajo presión autógena a 100 ° C, a tiempos de cristalización de 2–24h. los materiales sintetizados se caracterizaron por DRX, área específica BET y SEM. Se realizaron una serie de pruebas de síntesis para estudiar la influencia de la composición molar de la mezcla de partida sobre la cristalización. Se estudió el efecto del tiempo de cristalización para una composición de mezcla de síntesis particular para ambos tipos zeolitas, la reutilización como medio alcalino del licor madre separado durante la filtración, y el efecto del envejecimiento antes de la cristalización. Los resultados experimentales están de acuerdo con el mecanismo propuesto de cristalización para la síntesis de zeolitas en fase líquida. El uso de una composición de 2SiO2: Al2O3: 6.Na2O: 240H2O en la síntesis permite la obtención de zeolita LTA a partir de 2h de cristalización. Para la zeolita FAU, no se requirió de período de envejecimiento cuando se parte de la composición 4SiO2: Al2O3: 6.6Na2O: 264H2O. Fue posible sintetizar ambas zeolitas con alta pureza y cristalinidad y propiedades adecuadas de adsorción de agua.

License

Copyright (c) 2016 Adriana Lucía García, Carmen Milena López, Luis Vicente García, Mireya Rincón de Goldwasser, Johliny Del Carmen Casanova

Creative Commons License

This work is licensed under a Creative Commons Attribution 4.0 International License.

The authors or holders of the copyright for each article hereby confer exclusive, limited and free authorization on the Universidad Nacional de Colombia's journal Ingeniería e Investigación concerning the aforementioned article which, once it has been evaluated and approved, will be submitted for publication, in line with the following items:

1.    The version which has been corrected according to the evaluators' suggestions will be remitted and it will be made clear whether the aforementioned article is an unedited document regarding which the rights to be authorized are held and total responsibility will be assumed by the authors for the content of the work being submitted to Ingeniería e Investigación, the Universidad Nacional de Colombia and third-parties;

2.    The authorization conferred on the journal will come into force from the date on which it is included in the respective volume and issue of Ingeniería e Investigación in the Open Journal Systems and on the journal's main page (https://revistas.unal.edu.co/index.php/ingeinv), as well as in different databases and indices in which the publication is indexed;

3.    The authors authorize the Universidad Nacional de Colombia's journal Ingeniería e Investigación to publish the document in whatever required format (printed, digital, electronic or whatsoever known or yet to be discovered form) and authorize Ingeniería e Investigación to include the work in any indices and/or search engines deemed necessary for promoting its diffusion;

4.    The authors accept that such authorization is given free of charge and they, therefore, waive any right to receive remuneration from the publication, distribution, public communication and any use whatsoever referred to in the terms of this authorization.