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Ag functionalized Carbon Molecular Sieves membranes for separating O2 and N2

Published online by Cambridge University Press:  11 February 2011

J. N. Barsema ,
J. Balster ,
N. F. A. Van der Vegt ,
G. H. Koops ,
V. Jordan  and
M. Wessling
J. N. Barsema
Affiliation:
Membrane Technology Group, Faculty of Chemical Technology, University of Twente, Enschede, The Netherlands.
J. Balster
Affiliation:
Membrane Technology Group, Faculty of Chemical Technology, University of Twente, Enschede, The Netherlands.
N. F. A. Van der Vegt
Affiliation:
Membrane Technology Group, Faculty of Chemical Technology, University of Twente, Enschede, The Netherlands.
G. H. Koops
Affiliation:
Membrane Technology Group, Faculty of Chemical Technology, University of Twente, Enschede, The Netherlands.
V. Jordan
Affiliation:
Department of Chemical Engineering, Fachhochschule Münster - University of Applied Sciences, Steinfurt, Germany
M. Wessling
Affiliation:
Membrane Technology Group, Faculty of Chemical Technology, University of Twente, Enschede, The Netherlands.
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Abstract

In the last two decades substantial progress has been made in the preparation of Carbon Molecular Sieve (CMS) membranes for gas separation. Today, researchers actively study precursor materials and pyrolysis routes to fully explore the merits of CMS membranes. Successful separation of permanent gas mixtures in which the gaseous components posses only little to no affinity to adsorb onto the internal CMS surface relies highly on the exact tailoring of microsieving regions. Preparation of CMS structures, which are highly permselective towards one of such mixture components, is especially cumbersome if the molecular sizes differ only slightly (e.g. O2/N2).

To facilitate the separation of O2 and N2 we have chosen to functionalize the carbon matrix. By introducing nano-sized (40 nm) metallic Ag-clusters, the affinity of the membrane matrix for O2 significantly increases. We have added a silver containing salt, AgNO3, to a solution of BMTA-TDI/MDI co-polyimide (P84, Lenzing) in NMP in the absence of light to obtain homogeneous flat film polymeric precursors. These precursors were pyrolysed, reducing Ag+ to Ag, at different temperatures (350, 500, 600, 700, and 800 °C) in a N2 atmosphere and characterized using Scanning Electron Microscopy, Atomic Force Microscopy, and gas permeation. Thermo Gravimetrical Analysis was used to follow the pyrolysis in detail. From this we observed an increase of the ideal separation factor of 1.6. Moreover, we observed an increase of the permeability to a maximum of 240 %.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 752: Symposium AA – Membranes–Preparation, Properties and Applications , 2002 , AA10.2
Copyright
Copyright © Materials Research Society 2003

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References

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