Carbon-based molecular sieve membranes for gas separation by inductively-coupled-plasma chemical vapor deposition

✍ Scribed by Liang-Jun Wang; Franklin Chau-Nan Hong

• Publisher: Elsevier Science
• Year: 2005
• Tongue: English
• Weight: 345 KB
• Volume: 77
• Category: Article
• ISSN: 1387-1811
• DOI: 10.1016/j.micromeso.2004.09.001

✦ Synopsis

Carbon-based molecular sieve (CMS) films for gas separation have been deposited on porous Al 2 O 3 disks using hexamethyldisiloxane (HMDSO) by a remote inductively-coupled-plasma (ICP) chemical vapor deposition (CVD) method. The H 2 /N 2 selectivities of the as-deposited films falled into the range of 5-10, higher than the Knudsen diffusion selectivity, 3.7. After pyrolysis of the as-deposited film at 873 K, the permeance increased by one order of magnitude with no significant change of the selectivity. A surface treatment method was further employed by bombarding the as-deposited film with high energy ions of HMDSO. After pyrolysis at 823 K, the surface-treated film exhibits a very significant increase of H 2 /N 2 selectivity without any reduction of the permeance. The H 2 /N 2 selectivity could reach 30-45 with an extremely high permeance around 2 • 10 À6 mol m À2 s À1 Pa À1 at 423 K. The O 2 /N 2 selectivity reached 3.8 and the O 2 permeance was about 2 • 10 À7 mol m À2 s À1 Pa À1 at 298 K. Therefore, a new method for preparing carbon-based molecular sieve membranes has been introduced by combining the surface treatment with high energy ion bombardment and the subsequent high temperature pyrolysis.