Synthesis and characterization of nanocomposite B-MFI-alumina hollow fibre membranes and application to xylene isomer separation

In this study, Al-MFI and B-MFI hollow fibre membranes with nanocomposite architecture have been prepared by pore-plugging hydrothermal synthesis at 443 K for 89 h using a precursor clear solution with the molar composition 1 SiO2: 0.45 TPAOH: 27.8 H2O: (0.01 H3BO3). The structure and morphology of the synthesized materials has been analyzed by XRD, FTIR, ICP-AES, MAS-NMR, SEM and single gas permeation, reflecting in the case of B-MFI samples partial isomorphous substitution of framework Al and Si by boron (up to 1 B atom/uc). The separation performance of the membranes has been evaluated by n-butane/H2 and xylene isomer separations. The B-MFI hollow fibre membranes show improved separation performance towards p-xylene separation compared to conventional Al-based MFI-alumina hollow fibre membranes. Pre-adsorption of n-hexane or TMB has little effect on ternary xylene separation, suggesting the absence of intercrystalline mesoporous domains.