Metal-Supported Carbogenic Molecular Sieve Membranes:  Synthesis and Applications

Carbogenic molecular sieve membranes supported on macroporous sintered stainless steel flat plates have been synthesized by pyrolysis of a (poly)furfuryl alcohol−acetone solution imbibed within the surface pores of the support. Permeances of H2, He, Ar, O2, N2, and SF6 were measured to determine the permselectivity of these membranes. Experiments performed on flat-plate membranes revealed molecular sieving behavior with the permeance decreasing with increasing molecular size. Separation factors of 2−3 for O2/N2 and up to 30 for H2/N2 were obtained from single gas permeation experiments at 293 K. Higher temperature experiments demonstrated the activated nature of transport of various molecules. A 1:1 O2/N2 mixture was partially separated over a range of pressures at steady state. The lack of pressure dependence of the permeances indicated that shape- and size-selective effects dominated the separation. An EDAX analysis of the flat-plate surface reveals a defect-free CMS layer.