Aliphatic aromatic polyimide blends for H2 separation

M.G. GARCIA; J. MARCHESE; N. A. OCHOA

INTERNATIONAL JOURNAL OF HYDROGEN ENERGY

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Londres; Año: 2010 p. 1 - 10

0360-3199

In this work the synthesis of a semi aliphatic BTDA-DAH polyimide and their blends withBTDA-ODA and BTDA-DDS polyimides was carried out in order to improve the H2 permselectiveproperties of polyimides. The syntheses were made using the well-known twosteps method and the silylation method. The prepared films were characterized by FTIR,DSC, thermal stability and fluorescence spectroscopy. Intercatenary distances (d-spacing)and gas separation properties were also investigated. PI blend membranes presented onlyone glass transition temperature (Tg) intermediate between those of the neat polyimides.Fluorescence spectra were a useful tool to recognize electron-donor and electron-acceptorinteractions indicating intermolecular charge-transfer complex (CTC) formation whichwere confirmed by UVeVis absorptions. As a result, a decrease in the intercatenarydistances and a shift for both IR and fluorescence bands of polyimide blends weremeasured. PI blend membranes showed a permeability decrease with respect to the neatones, while the selectivity increased according to X-ray diffraction results. To analyze thepolyimide blend permselectivities, H2/CH4, H2/CO2, H2/O2 and H2/N2 systems were chosen.As a result, H2/CH4 separation factor of PI blends was among the highest reported by otherauthors using traditional membrane materials.