Novel nanoporous carbon membranes for gas separation
- Air Products and Chemicals, Inc., Allentown, PA (United States)
A new class of gas separation membranes has been developed which consist of thin, nanoporous (pore diameters of 5-6{angstrom}) layers of adsorbent carbon supported on a macroporous support Gas separation is accomplished by selective adsorption, and selective surface flow of the more strongly adsorbed component of the feed gas mixture. Thus, the less strongly adsorbed components are retained at feed pressure. The presence of the adsorbed layer severely hinders the permeation of the less strongly adsorbed components resulting in very high permeation selectivities. Since adsorption selectivities are high even at relatively low pressure, high permeation selectivities have been achieved at low feed gas pressure. The membranes are prepared by controlled pyrolysis of a thin layer of polyvinylidene chloride polymer supported on a porous support material. The resultant carbon separating layer is approximately 1-3 microns in thickness. These membranes are ideally suited for recovery of hydrogen from hydrocarbons from low pressure refinery waste gases. The key advantage of these membranes is that hydrogen is retained at feed pressure which significantly reduces the energy required for recovery. The membranes have been tested using a simulated refinery waste stream containing hydrogen and C{sub 1}-C{sub 4} hydrocarbons. Butane-hydrogen selectivity of {approximately}100 has been achieved with butane permeabilities of 120 Barrers. A process has been designed which utilizes these membranes for hydrogen recovery from refinery waste gases. This paper describes the preparation of these membranes, their permeation properties for pure and mixed gases, and application of membranes for hydrogen recovery.
- OSTI ID:
- 213095
- Report Number(s):
- CONF-940713--
- Country of Publication:
- United States
- Language:
- English
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