NAMS 2002 Workshop - ICOM 2008

Hybrid Membranes – 6
Thursday July 17, 5:00 PM-5:30 PM, Wai’anae
Preparation High Performance Microporous/Mesoporous Hybrid
Membranes for Gas Separation
Q. Liu (Speaker), Dalian University of Technology, Dalian, China
X. Zhao, Dalian University of Technology, Dalian, China
T. Wang, Dalian University of Technology, Dalian, China - wangth@chem.dlut.edu.cn
S. Liu, Dalian University of Technology, Dalian, China
Y. Cao, Dalian Institute of Chemical Physics, Dalian, China
J. Qiu, Dalian University of Technology, Dalian, China
Carbon molecular sieving (CMS) membrane is considered to be one of the most
promising inorganic membrane materials for membrane-based gas separation
because of their excellent selectivity and thermal and chemical stability even
under harsh conditions, such as high pressure and high temperature. However,
the separation performance of this material still can not satisfy the practical
application requirement owing to their low permeability.
Herein, a novel carbon-based microporous/mesoporous hybrid membrane has
been successfully designed and prepared for gas separation. The as-synthesized
hybrid material is composed of continuous microporous carbon matrix and
dispersed mesoporous material SBA-15. It is well known that gas transport
through ordered mesoporous materials is governed by the Knudsen diffusion
mechanism with negligible contribution from viscous flow. Therefore, the gas
diffusion rate in the mesoporous materials is several orders of magnitude faster
than that in microporous materials. The incorporation of mesoporous material
SBA-15 will help to increase the gas diffusion rate in the membranes and
improve the gas separation performance.
The characterization results conducted by XRD, TEM and nitrogen sorption
analysis indicated that the mesoporous material SBA-15 was well dispersed in
the carbon matrix and the mesoporous structure of SBA-15existed in hybrid
membrane was not destroyed during pyrolysis. The gas permeation tests using
small molecules (H2, CO2, O2, N2 and CH4) showed that the hybrid membrane
exhibited outstanding permeability together with high selectivity, which indicated
that gas transport through the hybrid membranes was still controlled by the
molecular sieving effect. The correlation of the permeability versus the selectivity
for the hybrid membrane showed higher values than the Robeson upper bounds
for polymeric membranes. And the gas separation performance of the
membranes were also higher than the polyimide-derived carbon membranes.
The excellent gas separation performance for all tested gases makes the
microporous/mesoporous hybrid membrane an attractive material in gas
separation areas.