A high molecular weight polyimide (Matrimid) was used as a precursor for fabricating supported carbon molecular sieve membranes without crack formation at 550-700°C pyrolysis temperature. A one-step polymer (polyimide) coating method as precursor of carbon layer was used without needing a prior modification of a TiO 2 macroporous support. The following fabrication variables were optimized and studied to determine their effect on the carbon structure: polymeric solution concentration, solvent extraction, heating rate and pyrolysis temperature. Two techniques (Thermogravimetric analysis and Raman spectroscopy) were used to determine these effects on final carbon structure. Likewise, the effect of the support was also reported as an additional and important variable in the design of supported carbon membranes. Atomic force microscopy and differential scanning calorimetry quantified the degree of influence. Pure gas permeation tests were performed using CH 4, CO, CO 2 and H 2. The presence of a molecular sieving mechanism was confirmed after defects were plugged with PDMS solution at 12wt%. Gas selectivities higher than Knudsen theoretical values were reached with membranes obtained over 650°C, showing as best values 4.46, 4.70 and 10.62 for H 2/N 2, H 2/CO and H 2/CH 4 ratio, respectively. Permeance values were over 9.82×10 -9mol/(m 2Pas)during pure hydrogen permeation tests. © 2012 Elsevier B.V.
|Original language||English (US)|
|Number of pages||10|
|Journal||Journal of Membrane Science|
|State||Published - Oct 2012|
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledgements: The authors are indebted to the Spanish Government for financial support (project CTQ2008-02491, partially funded by the FEDER program of the European Union) and to the commission of European Communities Specific OpenTok ProjectMTKD-LT-2005-030040. Dr. S. Nunes from the Water Desalination and Reuse Center at the King Abdullah University of Science and Technology (KAUST), Kingdom of Saudi Arabia, is acknowledged for providing the Matrimid polymer. Dr. J. L. Toca from the Department of Naniobiotechnology BOKU-Vienna and Dr. A. Lederer from the Leibniz-Institute of Polymer Research Dresden are acknowledged for their assistance with the AFM and Light Scattering measurements, respectively. Special thanks to Dr. Marta Giamberini and Dr. Jose Antonio Reina from Rovira I Virgili University for their support on realization of experiments.
This publication acknowledges KAUST support, but has no KAUST affiliated authors.