Preparation and Evaluation of Nanocomposite Sodalite/α-Al₂O₃ Tubular Membranes for H₂/CO₂ Separation

Nanocomposite sodalite/ceramic membranes supported on α-Al₂O₃ tubular support were prepared via the pore-plugging hydrothermal (PPH) synthesis protocol using one interruption and two interruption steps. In parallel, thin-film membranes were prepared via the direct hydrothermal synthesis technique. The as-synthesized membranes were evaluated for H₂/CO₂ separation in the context of pre-combustion CO₂ capture. Scanning electron microscopy (SEM) was used to check the surface morphology while x-ray diffraction (XRD) was used to check the crystallinity of the sodalite crystals and as-synthesized membranes. Single gas permeation of H₂, CO₂, N₂ and mixture gas H₂/CO₂ was used to probe the quality of the membranes. Gas permeation results revealed nanocomposite membrane prepared via the PPH synthesis protocols using two interruption steps displayed the best performance. This was attributed to the enhanced pore-plugging effect of sodalite crystals in the pores of the support after the second interruption step. The nanocomposite membrane displayed H₂ permeance of 7.97 × 10^-7 mol·s^-1·m^-2·Pa^-1 at 100 °C and 0.48 MPa feed pressure with an ideal selectivity of 8.76. Regarding H₂/CO₂ mixture, the H₂ permeance reduced from 8.03 × 10^-7 mol·s^-1·m^-2·Pa^-1 to 1.06 × 10^-7 mol·s^-1·m^-2·Pa^-1 at 25 °C and feed pressure of 0.18 MPa. In the presence of CO₂, selectivity of the nanocomposite membrane reduced to 4.24.