NAMS 2002 Workshop - ICOM 2008

Inorganic Membranes II – 1 – Keynote
Thursday July 17, 8:15 AM-9:00 AM, O’ahu/Waialua
High Temperature Gas Permeation Characteristics of MFI and DDR type
Zeolite Membranes
J. Lin (Speaker), Arizona State University, Tempe, Arizona, USA - Jerry.Lin@ASU.EDU
M. Kanezashi, Arizona State University, Tempe, Arizona, USA
J. O'Brien-Abraham, Arizona State University, Tempe, Arizona, USA
X. Zhu, Arizona State University, Tempe, Arizona, USA
This presentation compares synthesis and gas permeation/separation properties
of two thermally stable zeolite membranes: intermediate pore MFI type and small
pore DDR type zeolite membranes. These membranes have minimized defects
and pinholes and exhibit unique gas separation and permeation properties for
separation and membrane reactor applications. Experimental data for permeation
of small gases such as hydrogen, helium, carbon dioxide and carbon monoxide
through these two zeolite membranes in the temperature range of 25-500°C will
be presented and analyzed by the translational gas permeation model. The
permeation and separation properties of these small gases at high temperatures
for these microporous membranes feature a combined Knudsen and activated
diffusion mechanisms, depending on the relative size of the diffusing gas to the
membrane pores and quality of the membranes. The experimental data show
that at high temperatures the molecules of these gases in the zeolite pores retain
their gas characteristics. For MFI type zeolite membranes, the permeance
decreases with increasing temperature and is determined by the molecular
weight, not the kinetic diameter of the molecules. Diffusion of small molecules in
the small pore DDR type zeolite membranes exhibits activated process, with
permeance decrease with increasing size of the molecules.