An in situ energy-dispersive X-ray diffraction study of the hydrothermal crystallization of zeolite A. 2. Effect of deuteration on crystallization kinetics
Energy-dispersive X-ray diffraction has been used to follow the crystallization of zeolite A from amorphous aluminosilicate gels at 100 °C. Determination of changing Bragg peak intensity with time allows accurate quantitative kinetic information to be obtained: For the first time the effect of deute...
| Main Authors: | , |
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| Format: | Journal article |
| Language: | English |
| Published: |
2001
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| Summary: | Energy-dispersive X-ray diffraction has been used to follow the crystallization of zeolite A from amorphous aluminosilicate gels at 100 °C. Determination of changing Bragg peak intensity with time allows accurate quantitative kinetic information to be obtained: For the first time the effect of deuteration of reagents on the kinetics of a zeolite crystallization has been studied in detail. The kinetics of crystallization in NaOH/H2O and NaOD/D2O have been quantified using the nucleation growth model of Avrami and Erofe'ev. We find that the induction time of crystallization is lengthened when NaOH is replaced by NaOD, but no retardation of crystallization rate is observed. We suggest that this is due to the dissolution of starting materials being the rate-controlling step of the overall reaction. The new kinetic results are discussed in relation to previously postulated zeolite crystallization mechanisms. © 2001 American Chemical Society. |
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