Thermal and hydrothermal stability of molecular sieve VPI-5 by in situ x-ray powder diffraction

Journal Article · Thu Feb 07 04:00:00 EST 1991 · Journal of Physical Chemistry; (United States)

DOI:https://doi.org/10.1021/j100156a064· OSTI ID:5172882

Annen, M J; Young, D; Davis, M E ^[1]; Cavin, O B; Hubbard, C R ^[2]

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1. Virginia Polytechnic Inst. and State Univ., Blacksburg (USA)
2. Oak Ridge National Lab., TN (USA)

The framework stability of the molecular sieve VPI-5 is studied at various conditions of temperature, pressure, and humidity. Dehydration of VPI-5, by either rapid heating or pressure reduction, leads to a contraction in a and an expansion in c (hexagonal cell). These changes are reversible upon rehydration. The transformation of VPI-5 into AlPO{sub 4}-8 depends on the rate at which water is removed from the pores. Slow heating results in the irreversible formation of AlPO{sub 4}-8 from VPI-5 at about 100C. However, VPI-5 rapidly heated to at least 550C can withstand exposure to steam at these elevated temperatures with little loss of structural integrity.

• OSTI ID: 5172882
• Journal Information: Journal of Physical Chemistry; (United States), Journal Name: Journal of Physical Chemistry; (United States) Vol. 95:3; ISSN JPCHA; ISSN 0022-3654
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360202* -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
ADSORBENTS
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CHALCOGENIDES
COHERENT SCATTERING
DATA
DIFFRACTION
EXPERIMENTAL DATA
HUMIDITY
INFORMATION
LATTICE PARAMETERS
MOLECULAR SIEVES
NUMERICAL DATA
OXIDES
OXYGEN COMPOUNDS
PHOSPHORUS COMPOUNDS
PHOSPHORUS OXIDES
PRESSURE EFFECTS
SCATTERING
TEMPERATURE EFFECTS
X-RAY DIFFRACTION