Carbon molecular sieve gas separation membranes based on an intrinsically microporous polyimide precursor

X. Ma, R. Swaidan, B. Teng, H. Tan, O. Salinas, E. Litwiller, Y. Han, I. Pinnau
Carbon, 62, pp. 88-96, (2013)

Carbon molecular sieve gas separation membranes based on an intrinsically microporous polyimide precursor

Keywords

Membrane

Abstract

​We report the physical characteristics and gas transport properties for a series of pyrolyzed membranes derived from an intrinsically microporous polyimide containing spiro-centers (PIM-6FDA-OH) by step-wise heat treatment to 440, 530, 600, 630 and 800 °C, respectively. At 440 °C, the PIM-6FDA-OH was converted to a polybenzoxazole and exhibited a 3-fold increase in CO2 permeability (from 251 to 683 Barrer) with a 50% reduction in selectivity over CH4 (from 28 to 14). At 530 °C, a distinct intermediate amorphous carbon structure with superior gas separation properties was formed. A 56% increase in CO2-probed surface area accompanied a 16-fold increase in CO2 permeability (4110 Barrer) over the pristine polymer. The graphitic carbon membrane, obtained by heat treatment at 600 °C, exhibited excellent gas separation properties, including a remarkable CO2 permeability of 5040 Barrer with a high selectivity over CH4 of 38. Above 600 °C, the strong emergence of ultramicroporosity (<7 Å) as evidenced by WAXD and CO2 adsorption studies elicits a prominent molecular sieving effect, yielding gas separation performance well above the permeability-selectivity trade-off curves of polymeric membranes.

Code

DOI: 10.1016/j.carbon.2013.05.057

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