Transport of aromatic molecules in NaY zeolite powders

Journal Article · Mon Oct 01 00:00:00 EDT 1990 · A.I.Ch.E. Journal (American Institute of Chemical Engineers); (United States)

DOI:https://doi.org/10.1002/aic.690361012· OSTI ID:5719182

Chmelka, B F; Gillis, J V; Petersen, E E; Radke, C J

This paper reports on Xenon-120 NMR that is used to probe macroscopic distributions of aromatic molecules adsorbed in a packed bed of 1-{mu}m NaY zeolite particles. Relative rates of guest transport through the intracrystalline (micro) and intercrystalline (macro) pores play a unique role in the axial distribution of sorbate molecules, such as hexamethylbenzene, in a zeolite powder. Xenon-129 NMR spectra show that a sharp HMB adsorption front advances through a bed of dehydrated NaY crystallites at 523 K. However, at 573 K or in the presence of coadsorbed water, HMB species disperse through the bed without forming a sharp boundary between adsorption zones. When guest transport is controlled by pseudosteady-state diffusion in the macropores, axial penetration of the bed by vapor-phase guest species occurs in a sharp adsorption front. A shrinking-core transport model then quantitatively estimates the intracrystalline diffusivities of HMB in dehydrated and partially hydrated NaY zeolite of 10{sup {minus}11} and 10{sup {minus}13} m{sup 2}/s, respectively, at 523 K. Xenon- 129 NMR proves to be a powerful tool for probing adsorbed guest distribution in zeolites, allowing relative time scales to be established for transport of molecular guests in NaY powders.

• OSTI ID: 5719182
• Journal Information: A.I.Ch.E. Journal (American Institute of Chemical Engineers); (United States), Journal Name: A.I.Ch.E. Journal (American Institute of Chemical Engineers); (United States) Vol. 36:10; ISSN AICEA; ISSN 0001-1541
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360602 -- Other Materials-- Structure & Phase Studies
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400101 -- Activation
Nuclear Reaction
Radiometric & Radiochemical Procedures
400105 -- Separation Procedures
54 ENVIRONMENTAL SCIENCES
540120* -- Environment
Atmospheric-- Chemicals Monitoring & Transport-- (1990-)
ADSORPTION
ALKALI METALS
ALKYL RADICALS
AROMATICS
BENZENE
CATALYTIC CONVERTERS
CATALYTIC EFFECTS
CHEMICAL REACTION KINETICS
DAYS LIVING RADIOISOTOPES
ELEMENTS
EQUIPMENT
EVEN-ODD NUCLEI
HYDROCARBONS
INORGANIC ION EXCHANGERS
INTERMEDIATE MASS NUCLEI
INTERNAL CONVERSION RADIOISOTOPES
ION EXCHANGE MATERIALS
ISOMERIC TRANSITION ISOTOPES
ISOTOPES
KINETICS
MATERIALS
METALS
METHYL RADICALS
MINERALS
NMR SPECTRA
NUCLEI
ORGANIC COMPOUNDS
POLLUTION CONTROL EQUIPMENT
RADICALS
RADIOISOTOPES
REACTION KINETICS
SILICATE MINERALS
SODIUM
SORPTION
SORPTIVE PROPERTIES
SPECTRA
STABLE ISOTOPES
SURFACE PROPERTIES
TRANSITION ELEMENTS
XENON 129
XENON ISOTOPES
YTTRIUM
ZEOLITES