Engineering substructure morphology of asymmetric carbon molecular sieve hollow fiber membranes Nitesh Bhuwania a,1 , Ying Labreche a,1 , Carine S.K. Achoundong a,1 , Jose Baltazar a,2 , Steven K. Burgess a,1 , Shweta Karwa a,1 , Liren Xu a,1 , Clifford L. Henderson a,1 , P. Jason Williams b,3 , William J. Koros a, * a School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA, United States b Shell International Exploration and Production (US) Inc., Houston, TX, United States ARTICLE INFO Article history: Received 1 February 2014 Accepted 3 May 2014 Available online 10 May 2014 ABSTRACT In this study, a novel pre-pyrolysis treatment is developed to restrict the morphology collapse in asymmetric carbon molecular sieve (CMS) hollow fiber membranes. The tech- nique is referred as V-treatment, due to the use of a sol–gel crosslinking reaction between an organic-alkoxy silane (vinyltrimethoxysilane) and moisture. The V-treatment technique enables restricting the microscale morphology collapse in asymmetric CMS membranes without having a chemical reaction with the polymer precursor material. The effect of V-treatment is reported on two different polyimide precursors: Matrimid â and 6FDA:BPDA-DAM. For both the CMS V-treated Matrimid â and 6FDA:BPDA-DAM hollow fibers, a significant reduction up to 5–6-fold in apparent membrane skin thickness is observed com- pared to the CMS from untreated precursors. This improvement translates to an increase in gas separation productivities for both pure and mixed gas feeds in CMS V-treated Matrimid â and 6FDA:BPDA-DAM hollow fiber membranes. Moreover, several characterization analyses and transport results for V-treatment method using 100% VTMS are reported herein. Ó 2014 Elsevier Ltd. All rights reserved. 1. Introduction Carbon molecular sieve (CMS) membranes show great poten- tial for several gas separation applications including natural gas purification (CO 2 ,N 2 removal from CH 4 ) [1–4], air separa- tion (O 2 from N 2 ) [5], and olefin/paraffin separation [6–8]. CMS membranes possess the ability to transcend the ‘‘poly- mer upper bound trade-off line’’ for separation performance http://dx.doi.org/10.1016/j.carbon.2014.05.008 0008-6223/Ó 2014 Elsevier Ltd. All rights reserved. * Corresponding author. Address: Georgia Institute of Technology, School of Chemical and Biomolecular Engineering, 778 Atlantic Drive, Atlanta, GA 30332, United States. E-mail addresses: bhuwania.nitesh@gmail.com (N. Bhuwania), ydai32@mail.gatech.edu (Y. Labreche), carachou16@gmail.com (C.S.K. Achoundong), jbaltazar13@gmail.com (J. Baltazar), sburgess3@gatech.edu (S.K. Burgess), shweta.karwa@chbe.gateh.edu (S. Karwa), lxu1@dow.com (L. Xu), cliff.henderson@chbe.gatech.edu (C.L. Henderson), p.j.williams@shell.com (P.J. Williams), wjk@chbe. gatech.edu (W.J. Koros). 1 Address: Georgia Institute of Technology, School of Chemical and Biomolecular Engineering, 778 Atlantic Drive, Atlanta, GA 30332, United States. 2 Address: Georgia Institute of Technology, School of Chemical and Biomolecular Engineering, 311 Ferst Drive, Atlanta, GA 30332, United States. 3 Address: Shell International Exploration and Production (US) Inc., 3333 Highway 6 South, Houston, TX 77082, United States. CARBON 76 (2014) 417 – 434 Available at www.sciencedirect.com ScienceDirect journal homepage: www.elsevier.com/locate/carbon