Importance

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Abstract

A gas-separation membrane enables the economical separation of noble gases, especially xenon, from oxygen, nitrogen, carbon dioxide or mixtures of the latter gases. The membrane of the present invention includes a thin discriminating layer selected from the group consisting of polycarbonate, polyester, and polyestercarbonate. In the preferred embodiment, the thin discriminating layer includes material selected from the bisphenolic group consisting of 2,2-bis(3,5-dibromo-4-hydroxyphenyl)propane, 2,2-bis(3,5-dichloro-4-hydroxyphenyl)propane, and 9,9-bis(3,5-dibromo-4-hydroxyphenyl)fluorene. The invention also includes the method of using the membrane, made as described above, either in a single-stage process or in a multiple-stage process, to provide the desired product gas. Several membrane units, made according to the present invention, may be manifolded together so as to operate in a parallel fashion, to provide an increased volume of product gas at the same desired purity. Alternatively, two or more membrane devices may be connected in a series or staged configuration to provide a smaller volume of highly purified product gas.

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First Claim