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Estudios de difracción de neutrones de hidrato de gas con resolución en el tiempo in situ: transformación de la
Y Halpern1, V Thieu, R W Henning
1Energy Systems Division, Argonne National Laboratory, Argonne, Illinois 60439, USA.
Journal of the American Chemical Society
|December 26, 2001
Resumen
Los investigadores observaron una transformación de la red de hidrato de gas de la estructura II a la estructura I utilizando difracción in situ. Este cambio estructural fue inducido por el intercambio de gases de CO2 en el hidrato de argón, formando un hidrato mixto.
Área de la Ciencia:
- Ciencia de los materiales Ciencia de los materiales.
- La cristalografía es una técnica de cristalografía.
- Química Física es la química física.
Sus antecedentes:
- Los hidratos de gas exhiben estructuras cristalinas distintas (por ejemplo, estructura I y estructura II).
- Comprender las transiciones de fase en los hidratos de gas es crucial para diversas aplicaciones, incluido el almacenamiento de energía y el secuestro de carbono.
Objetivo del estudio:
- Para investigar la conversión in situ de una red de hidrato de gas de estructura II (sII) a una red de estructura I (sI).
- Aclarar el mecanismo de la transformación estructural inducida por el intercambio de moléculas invitadas.
Principales métodos:
- La difracción de polvo de neutrones de tiempo de vuelo se empleó para la observación in situ.
- Los experimentos se llevaron a cabo a temperaturas de 230 a 263 K y presiones de hasta 5000 psi.
- Se utilizaron cristales de hielo deuterados como material de partida, con gas argón para la formación de hidratos y CO2 para el intercambio.
Principales resultados:
- Se observó una transformación completa de hielo D(2) O a hidrato de argón sII después del calentamiento.
- El hidrato de argón sII se transformó con éxito en un hidrato de sI tras la exposición al CO2).
- El hidrato SI resultante fue identificado como una mezcla de hidrato de argón/CO2, lo que indica un intercambio de moléculas invitadas.
Conclusiones:
- Las estructuras de hidrato de clatrato se pueden convertir entre diferentes redes (sII a sI) bajo condiciones específicas.
- El intercambio de moléculas invitadas es un mecanismo viable para inducir transformaciones estructurales en hidratos de gas.
- Los hidratos de gas se comportan como sistemas de equilibrio que permiten el intercambio de moléculas encapsuladas.
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