TY - JOUR
T1 - Silica membranes for hydrogen separation prepared by chemical vapor deposition (CVD)
AU - Khatib, Sheima J.
AU - Oyama, S. Ted
N1 - Funding Information:
The authors are grateful for support of this work from the Fundação de Ciência, Aplicações e Tecnologia Espaciais (FUNCATE), and the Ministry of Education, Science, Sports and Culture (MEXT), Grant-in-Aid for Scientific Research (B) (22360335).
PY - 2013
Y1 - 2013
N2 - Hydrogen separation membranes are important in the gas separation field and among these, silica-based membranes have emerged as promising materials at high temperatures due to their high permeation rates, high selectivity, hydrothermal stability, resistance to poisons, and mechanical strength. A critical review of the preparation of silica membranes by chemical vapor deposition (CVD) is given, with special attention placed on the two major supports used, Vycor glass and porous alumina. The coverage includes the different gas transport mechanisms that occur through silica membranes, which are convective flow, Knudsen diffusion, molecular sieving, activated diffusion, and solid-state diffusion. A description is made of the two main CVD geometries, which are the "one-sided" feed and "opposing reactants" feed configurations. The results of numerous studies in which CVD precursors such as silicon alkoxides and organosilicon species, as well as non-silicon element compounds are used to control pore size and surface properties are presented. Also the effect of varying reaction conditions such as temperature, pressure, and reaction time are compared. Finally, the permeation properties of the silica membranes are compared to those of palladium membranes, both types of membranes are employed for hydrogen separation in membrane reactors, and the advantages of silica membranes in these reactor systems are discussed.
AB - Hydrogen separation membranes are important in the gas separation field and among these, silica-based membranes have emerged as promising materials at high temperatures due to their high permeation rates, high selectivity, hydrothermal stability, resistance to poisons, and mechanical strength. A critical review of the preparation of silica membranes by chemical vapor deposition (CVD) is given, with special attention placed on the two major supports used, Vycor glass and porous alumina. The coverage includes the different gas transport mechanisms that occur through silica membranes, which are convective flow, Knudsen diffusion, molecular sieving, activated diffusion, and solid-state diffusion. A description is made of the two main CVD geometries, which are the "one-sided" feed and "opposing reactants" feed configurations. The results of numerous studies in which CVD precursors such as silicon alkoxides and organosilicon species, as well as non-silicon element compounds are used to control pore size and surface properties are presented. Also the effect of varying reaction conditions such as temperature, pressure, and reaction time are compared. Finally, the permeation properties of the silica membranes are compared to those of palladium membranes, both types of membranes are employed for hydrogen separation in membrane reactors, and the advantages of silica membranes in these reactor systems are discussed.
KW - Chemical vapor deposition
KW - Hydrothermal stability
KW - Permeation mechanism
KW - Pore size
KW - Porous alumina supports
KW - Silica membranes
KW - Vycor glass supports
UR - http://www.scopus.com/inward/record.url?scp=84876204795&partnerID=8YFLogxK
U2 - 10.1016/j.seppur.2013.03.032
DO - 10.1016/j.seppur.2013.03.032
M3 - Review article
AN - SCOPUS:84876204795
SN - 1383-5866
VL - 111
SP - 20
EP - 42
JO - Separation and Purification Technology
JF - Separation and Purification Technology
ER -