Carbon molecular sieves and a process for their preparation and use
First Claim
1. A carbon molecular sieve prepared from a naturally occurring substrate which is capable of separating gas or liquid mixtures containing components of at least two different molecular diameters, molecular weights or molecular shapes, said molecular sieve selected from the group consisting of molecular sieves having an average effective pore diameter of from about 3 to about 20 Angstroms and having:
- (a)(i) an oxygen diffusivity of 800×
10-8 cm2 /sec or less and(ii) a diffusivity ratio or 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 or oxygen to nitrogen greater than 100;
or(c)(i) an oxygen diffusivity greater than 800×
10-8 cm2 /sec and(ii) a diffusivity ratio of oxygen to nitrogen greater than 5.
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Abstract
The instant invention is directed to carbon molecular sieves which are capable of separating gas or liquid mixtures containing components of at least two different molecular diameters, molecular weights or molecular shapes, said molecular sieve having an average effective pore diameter of from about 3 to about 20 Angstroms and having specified oxygen diffusivities and selectivity ratios.
The instant invention is also directed to a process for preparing carbon molecular sieves having average effective pore diameters of from about 3 to about 20 Angstroms which comprises continuously feeding an agglomerated naturally occurring substrate to a continuous transport type heating means and calcining said agglomerated substrate in a substantially oxygen-free environment under a cocurrent purge of an inert gas at a temperature range of about 250° to 1100° C. for at least 1 minute.
The instant invention is also directed to the use of the carbon molecular sieves in separating gas or liquid mixtures containing components of at least two different molecular diameters, molecular weights or molecular shapes.
59 Citations
18 Claims
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1. A carbon molecular sieve prepared from a naturally occurring substrate which is capable of separating gas or liquid mixtures containing components of at least two different molecular diameters, molecular weights or molecular shapes, said molecular sieve selected from the group consisting of molecular sieves having an average effective pore diameter of from about 3 to about 20 Angstroms and having:
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(a) (i) an oxygen diffusivity of 800×
10-8 cm2 /sec or less and(ii) a diffusivity ratio or 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 or oxygen to nitrogen greater than 100;
or(c) (i) an oxygen diffusivity greater than 800×
10-8 cm2 /sec and(ii) a diffusivity ratio of oxygen to nitrogen greater than 5. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A process for preparing carbon molecular sieves having average effective pore diameters of from about 3 to about 20 Angstroms which comprises continuously feeding an agglomerated naturally occurring carbonaceous substrate to a continuous transport type heating means and calcining said agglomerated substrate under non-activation conditions and under a purge of an inert gas at a rate of 1.2 to 9.2 feet/minute at a temperature range of about 250°
- to 1100°
C. for at least 1 minute. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17, 18)
- to 1100°
Specification