A carbon gutter layer-modified α-Al2O3 substrate for PPO membrane fabrication and CO2 separation

A PPO membrane supported on the surface of inorganic carbon-modified α-Al2O3 substrate was prepared. The separation performance of this multi-layer composite membrane was found to be comparable to that of homogeneous PPO membranes. Intermediate carbon films acting as a gutter layer were fabricated to modify the surface roughness and surface pore size of α-Al2O3 substrate. To obtain different structures of carbon gutter layer, three kinds of thermal plastic precursors, namely, PPO, PEI, and PPSU, were pyrolyzed under different conditions. Results indicated that the roughness and surface pore size of α-Al2O3 substrate were decreased by the carbon gutter layer. This decrease benefited the PPO/C/α-Al2O3 composite membranes, which exhibited high CO2 gas permeability (147.5 Barrer) and CO2/N2 and CO2/CH4 selectivities (20.4 and 19.3, respectively).