TG and DSC investigation of the dehydration of the extra large pore aluminophosphate molecular sieve VPI-5 and related materials |
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Authors: | E. Segal L. Maistriau E. G. Derouane Z. Gabelica |
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Affiliation: | (1) Department of Physical Chemistry, University of Bucharest, Faculty of Chemistry, Bulevardul Republicii, 13 Bucharest, Romania;(2) Laboratoire de Catalyse, Facultes Universitaires N.D. de la Paix, 61 Rue de Bruxelles, B-5000 Namur, Belgium |
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Abstract: | ![]() The dehydration of a series of VPI-5 and H3 samples, synthesized under various conditions, as well as the solid state transformation of VPI-5 to AlPO4-8 have been investigated using combined TG-DTG-DSC and high-resolution solid state31P-NMR. The TG curves show a quasi-continuous release of water, the total loss being characteristic for each sample. Complete dehydration is achieved when the samples are heated from 20°C to about 150°C at various beating rates. Besides the main dehydration effect, several weak endothermic peaks are observed. These generally non-reproducible modulated peaks, recorded at high heating rates, are presumably due to the interactions of the water molecules leaving the channels of VPI-5 with the randomly positioned fragments stemming from the destruction of the water triple helix assemblage. The non-isothermal kinetic parameters of the dehydration have been evaluated from the TG and DTG curves recorded at low heating rates. In celebration of the 60th birthday of Dr. Andrew K. Galwey |
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Keywords: | dehydration extra-large pore aluminophosphate kinetics TG-DTG-DTA |
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