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Predecir el transporte de gases en adsorbentes de zeolita formados a partir de estudios de RMN
Frank Rittig1, Charles G Coe, John M Zielinski
1Air Products and Chemicals, Inc., Allentown, Pennsylvania 18195, USA.
Journal of the American Chemical Society
|May 9, 2002
Resumen
Este estudio utiliza la resonancia magnética nuclear de gradiente de campo pulsado (RMN PFG) para investigar la difusión de gas en 5A zeolita. Un refinado modelo de difusión de largo alcance (LRDM) predice con precisión los coeficientes de difusión para las mezclas de gases.
Área de la Ciencia:
- Ciencia de los materiales Ciencia de los materiales.
- Ingeniería Química Ingeniería Química.
- Química Física es la química física.
Sus antecedentes:
- Las zeolitas son materiales porosos cruciales para la adsorción y separación de gases.
- Comprender la difusión de gases dentro de las zeolitas es esencial para optimizar los procesos industriales.
- Los modelos anteriores a menudo requieren parámetros complejos, lo que limita su poder predictivo.
Objetivo del estudio:
- Para investigar la auto-difusión de nitrógeno, metano y monóxido de carbono en 5A zeolita utilizando RMN de PFG.
- Validar y refinar el modelo de difusión de largo alcance (LRDM) para adsorbentes granulados.
- Desarrollar una nueva técnica de RMN en fase gaseosa para medir isotermas y exceso de superficie.
Principales métodos:
- Se empleó la espectroscopia de resonancia magnética nuclear de gradiente de campo pulsado (RMN-PFG) para medir los coeficientes de difusión.
- Se adaptó un refinado modelo de difusión de largo alcance (LRDM) utilizando la porosidad del adsorbente y los datos de isoterma.
- Se utilizó una nueva técnica de RMN en fase gaseosa para mediciones precisas de isotermia y exceso de superficie.
Principales resultados:
- La difusión de gases (N2, CH4, CO) en 5A zeolita fue descrita con precisión por el LRDM refinado.
- El modelo predijo con éxito los coeficientes de difusión para una mezcla ternaria de gases.
- Se determinaron factores de tortuosidad, que reflejan la compleja estructura de poros de la zeolita.
- La nueva técnica de RMN proporcionó isotermas de adsorción puras y multicomponentes precisas.
Conclusiones:
- El LRDM refinado, utilizando solo datos de porosidad e isoterma, modela efectivamente la difusión de gas en 5A zeolita.
- La RMN PFG combinada con el modelado avanzado proporciona un enfoque poderoso para caracterizar la difusión de gases en materiales porosos.
- La técnica de RMN en fase gaseosa desarrollada ofrece un método robusto para determinar el comportamiento de adsorción.
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