Nanocomposite MFI-alumina membranes via pore-plugging synthesisPreparation and morphological characterisation

Nanocomposite MFI-alumina and FAU-alumina Membranes: Synthesis, Characterization and Application to Paraffin Separation and CO2Capture

“…However, in the case of membrane M12 prepared on a 1.4-μm top layer support, a higher SF 6 permeance and a much lower n-/i-butane separation factor (3.6) is obtained. All these observations confirm the results already reported in a previous study [20], being attributed to a higher support reactivity in smaller macropores.…”

“…The outer layer had a porosity of about 33%, whereas the porosity of the other two layers was about 30%. Prior to synthesis, the quality of the supports was tested by a gas-liquid displacement method [20]. Only supports displaying first-bubble pressures higher than 80 kPa using ethanol were used for membrane synthesis.…”

“…The nanocomposite MFI-alumina membranes were prepared by in situ hydrothermal synthesis using the pore-plugging method described in previous studies [15,20]. A precursor clear solution was prepared by dissolving Aerosil 380 pyrogenic silica (Degussa) in an aqueous tetrapropylammonium hydroxide solution (TPAOH, Sigma-Aldrich) to the final molar composition 1.0 SiO 2 :y TPAOH:x H 2 O.…”

“…In addition to film-like zeolite membranes, nanocomposite MFI-alumina architectures (prepared either as tubes or hollow fibres) have shown high potential to improve membrane reproducibility and the gas permeation and separation performance [15][16][17][18][19][20][21][22]. In this architecture, in contrast to a film, the active phase is embedded into the host ceramic alumina porous network via pore-plugging in situ hydrothermal synthesis (without seeding).…”

“…In some cases, one heating interruption during the synthesis has been used to promote nutrient diffusion in the porous structure of the alumina support [18]. Detailed transmission electron micrographs have revealed that zeolite crystals plug neighbouring support pores [20], conferring to the material higher resistance to long-range thermal stresses during calcination and further cooling compared to supported zeolite films. This property makes nanocomposite membranes the materials of choice when large surface areas are involved.…”