Carbon–Al2O3–Ag composite molecular sieve membranes for gas separation

Phenolic resins loaded with two different inorganic fillers (boehmite (γ-AlO(OH)) and silver (Ag)) were used to prepare composite carbon membranes. Polymer solutions containing γ-AlO(OH) and AgNO3 were prepared and the effect of Ag on the transport properties of the composite membrane was evaluated. The polymer solutions were coated on α-Al2O3 tubes and carbonized in a single dipping-drying-pyrolysis step. After pyrolysis at 550 °C, γ-AlO(OH) yielded γ-Al2O3, and Ag agglomerated forming spherical nanoparticles of 30 nm in diameter. Ag loading enhanced the carbon membrane performance for several gas pairs of interest, especially for C3H6/C3H8 separation, where the C3H6/C3H8 permselectivity increased from a maximum of 15 to 38.

► Phenolic resins with boehmite (and silver) nanoparticles were pyrolyzed at 550 °C.
► Carbon–alumina and carbon–alumina–silver membranes were tested for gas separation.
► Membranes with Ag exhibited higher C3H6/C3H8 permselectivities.