A Hydrogen‐Permselective Silicon Oxycarbide Membrane Derived from Polydimethylsilane

Abstract

A novel microporous membrane has been prepared by modifying an asymmetric SiC support using polydimethylsilane (PMS). One membrane, pyrolyzed at 573 K, possesses H 2 /N 2 selectivity of ∼100 and H 2 permeance of 8.9 × 10 −8 molؒm −2 ؒs −1 ؒPa −1 at 473 K. The other membrane, pyrolyzed at 873 K, has a lower H 2 /N 2 selectivity of ∼40 and lower H 2 permeance of 4.9 × 10 −9 molؒm −2 ؒs −1 ؒPa −1 at 473 K. Permeation in both membranes exhibits the characteristics of activated diffusion at elevated temperatures. A higher pyrolysis temperature results in a less-permeable membrane. The support preparation and the thermal events of PMS are analyzed. The effects of pyrolysis temperature on membrane property are discussed.

Silicon carbide membranes for gas separation applications

“…Morooka and coworkers [4,13,14], for example, used a PCS that they cured in oxygen to prepare a Si-O-C membranes on ␥-and ␣-Al 2 O 3 tubular substrates with an oxygen content of 13-18 wt%, using polystyrene (PS) as the pore former. A membrane prepared with 1% PS had a H 2 permeance of 4 × 10 −8 mol m −2 s −1 Pa −1 , and an ideal H 2 /N 2 selectivity of 20 at 773 K. The membrane was unstable in Ar at 1223 K, and also hydrothermally unstable when exposed to a 7.8 wt% H 2 O in He mixture at 773 K. Lee and Tsai [15,16] prepared Si-C-O membranes by the pyrolysis of polydimethylsilane (PMS). The PMS undergoes a thermolytic reaction at 733 K for 14 h under 1 atm of Ar, followed by O 2 curing at 473 K for 1 h. The layer was finally pyrolyzed at various temperatures from 523 to 1223 K to produce the membranes.…”

Inorganic membranes for pre-combustion carbon dioxide (CO 2 ) capture

“…ASCM, characterized by larger pores, separate heavy molecules on the basis of an adsorption-surface migration mechanism, making possible their use for CO 2 separation (Sircar et al, 1999). Alternatively, organic silane precursors can be pyrolysed to obtain Si-O-C and SiC microporous membranes (Sea et al, 1998;Lee and Tsai 1999), which may have a better Liu et al (1999) supports stability than pure SiO 2 membranes in H 2 /CO 2 separation (Nam and Gavalas 1989).…”

Gas Permeation Properties of Amorphous SiC Membranes Synthesized from Polycarbosilane without Oxygen-Curing Process

“…[16][17][18]20 However, for fabricating thermally stable amorphous SiC-based membranes, it is essential that the starting precursor polymers be converted into amorphous material without functional groups like Si-H and Si-CH 3 . Based on the results of FT-IR and XRD analyses, the pyrolysis temperature for the amorphous SiC membrane synthesis in this study was selected as 1073 K. Then, the membrane synthesis and the effect of coating procedures on the gas permeation properties were further studied.…”