JDF-L1 is a microporous titanosilicate exhibiting a layer structure with pore size of about 3 Å. It is consequently an attractive material to separate H2-containing mixtures. This is the reason why JDF-L1, after disaggregation by means of hexadecyltrimethylammonium surfactant, has been combined with a carboxyl group containing copolyimide (6FDA-4MPD/6FDA-DABA 4:1) to produce mixed matrix membranes, which were applied to the separation of H2/CH4 and O2/N2 mixtures. Additionally, due to the sheet growth habit of JDF-L1 crystals, a preferential horizontal orientation of the JDF-L1 filler particles dispersed into the polymer was expected. This preferential orientation, which was achieved when the polymer solution concentration used during the membrane casting process was relatively low, has been studied by optical and electronic microscopy, X-ray diffraction and polarized Raman spectroscopy. A quantitative analysis was carried out applying Cussler's model for mixedmatrixmembranes with oriented flakes.

We gratefully thank the German Academic Exchange Service (DAAD) for the financial support within the budget of the project related person exchange program (PPP, 0804142). Also, financial support from the Spanish Science and Innovation Ministry (MAT2007-61028, CIT-420000-2009-32, and HD2008-0001) and the Aragon Government (PI035/09) is gratefully acknowledged.

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