Nanoporous polymer – Clay hybrid membranes for gas separation

Nanohybrid organo–inorgano clay mineral-polydimethylsiloxane (PDMS) membranes were prepared by the reaction of pure and/or modified natural clay minerals (Sepiolite and montmorillonite) with PDMS in hexane, followed by evaporation of the solvent at 70 °C. The membranes were characterized by means of XRD, SEM, ATD-TG and solid state 29Si magic angle spinning (MAS) and cross-polarization (CP) CP/MAS NMR. The morphology of the membranes depends on the content loading of clay mineral. For low content, the membrane composition is homogeneous, with well dispersed nanoparticles of clay into the polymer matrix, whereas for higher clay content, the membranes are constituted also of a mixture of well dispersed nanoparticles into the polymer, but in the presence of agglomerations of small clay particles. Quantitative 29Si MAS NMR demonstrated a strong correlation between the clay content of the membrane and the average length of the PDMS chain, indicating that the nanohybrid material is made of clay particles covalently linked to the PDMS structure. This is particularly the case for Sepiolite with has a high density of Q2 silanol sites. The separation performances of the prepared membranes were tested for CO2/CH4 and O2/N2 mixtures. The observed separation factors showed an increase of the selectivity in the case of CO2/CH4 in comparison with membranes made from PDMS alone under the same conditions.

Nanohybrid organo-inorgano clay mineral-polydimethylsiloxane (PDMS) membranes, with PDMS chains covalently linked to sepiolite microfibers, were synthesized, characterized and tested for the separation of CO2/CH4 and O2/N2 mixtures.Figure optionsDownload high-quality image (88 K)Download as PowerPoint slide