Influence of support structure on the permeation behavior of polyetherimide-derived carbon molecular sieve composite membrane

Polyetherimide (PEI) was used as polymeric precursor to prepare selective carbon molecular sieve (CMS) layer supported by a porous Al2O3 ceramic disk. The effects of the porous structure and surface roughness of the ceramic support on the interfacial adhesion and texture of the PEI/Al2O3-derived composite CMS membrane were investigated by modulating the sintering temperature and holding time. When the surface roughness of the ceramic support increased, the pore size and its distribution of the selective CMS layer were found to have shifted to the larger one and its roughness increased from the top to the bottom surface. This structure resulted in high permeability and low selectivity. Our results indicate that the porous structure of the ceramic support also played an important role in dominating the pore size and its distribution of the selective CMS layer, which influences the gas separation performance.

The movements of the crystal/grain have different features at each stage attributed to grain coarsening, pore closing, and full density, which will influence the gas permeation behavior through the support materials. The height fluctuation of the support surface nodule causes the polymer chain to be arrayed irregularly due to the rough surface of S1000-1, suggesting that effective transport of gas molecules through the microstructure can be obtained in CMS1000-1.Figure optionsDownload high-quality image (505 K)Download as PowerPoint slideHighlights
► The structure of support has influence on gas permeance of selective carbon layer.
► The structure of support was controlled by sintering treatment.
► Grain growth results in the rough surface of support and high permeance of membrane.
► The polymer chain was arrayed irregularly due to the rough surface of support.