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Carbon molecular sieves and a process for their preparation and use

  • US 4,627,857 A
  • Filed: 03/07/1985
  • Issued: 12/09/1986
  • Est. Priority Date: 12/13/1983
  • Status: Expired due to Term
First Claim
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1. A process for separating gas mixtures containing components of at least two different molecular diameters, molecular weights or molecular shapes comprising passing the gas through a carbon molecular sieve prepared from a naturally occurring substrate and selected from the group consisting of molecular sieves having:

  • (a)(i) an oxygen diffusivity of 800×

    10-8 cm2 /sec or less; and

    (ii) a diffusivity ratio of oxygen to nitrogen of 15 to 100;

    (b)(i) an oxygen diffusivity of 600×

    10-8 cm2 /sec or less; and

    (ii) a diffusivity ratio of oxygen to nitrogen greater than 100; and

    (c)(i) an oxygen diffusivity greater than 800×

    10-8 cm2 /sec; and

    (ii) a diffusivity ratio of oxygen to nitrogen greater than 5;

    here the diffusivity is measured using a starting gas pressure of one atmosphere (+/-5%) at a temperature of 25°

    +/-5% for 30 seconds.

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