Preparation of stable MCM-48 membranes

MARISA N. PEDERNERA; OSCAR DE LA IGLESIA; REYES MALLADA; JOAQUÍN CORONAS; Z. LIN; J. ROCHA; JESÚS SANTAMARÍA

JOURNAL OF MEMBRANE SCIENCE

Elsevier

Año: 2009 vol. 326 p. 137 - 144

0376-7388

Stable mesoporous membranes with a cubic structure, based on the MCM-48 material, were successfully  prepared on alumina supports by hydrothermal synthesis, starting fromsols having both CTABr and TPAOH structure directing agents. The inclusion of a zeolite (MFI-type) precursor during membrane synthesis led to partial zeolite incorporation into the porous structure, giving rise to a hydrothermally stable membrane. The mean pore diameter of the membrane was 2.5 nm, and permeation experiments confirmed that transport across the membrane was governed by Knudsen diffusion and that there were no pinholes. Thehydrothermal stability of conventionallyprepared(MCM-48) and partly zeolitized(MCMZ)powders was studied.UnlikeMCM-48 samples (whose surface area sharply decreased after the hydrothermal treatment), theMCMZsurface area remained constant (1031m2/g before and 1009m2/g after the hydrothermal treatment), indicating a high hydrothermal stability. MCMZmembraneswere tested in the gas phase separation of binary organic (cyclohexane, benzene and n-hexane)/O2 mixtures. A maximum selectivity of 124was obtained for the separation of cyclohexane/O2 mixtures. The selective permeation of the organic compound was made possible by specific interactions between the organic molecules and the mesoporous host materials, and/or by capillary condensation within the membrane pores.