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US 5,688,307 AGranted
Separation of low-boiling gases using super-glassy membranes
AssigneeMembrane Technology and Research, Inc.
InventorsIngo Pinnau, Kaaeid Lokhandwala, Phuong Nguyen, Scott Segelke
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Abstract
A process for separating hydrocarbon gases of low boiling point, particularly methane, ethane and ethylene, from nitrogen. The process is performed using a membrane made from a super-glassy material. The gases to be separated are mixed with a condensable gas, such as a C.sub.3+ hydrocarbon. In the presence of the condensable gas, improved selectivity for the low-boiling-point hydrocarbon gas over nitrogen is achieved.
Claims20
A gas-separation process comprising:
- (a) providing a membrane having a feed side and a permeate side;
- said membrane comprising a polymer material characterized by:
- (i) a glass transition temperature, T.sub.g, of at least about 100.degree. C.,
- (ii) a free volume V.sub.F of at least about 10% and
- (iii) a methane permeability at room temperature of at least about 1,000 Barrer;
- (b) contacting said feed side with a gas mixture comprising:
- (i) a hydrocarbon gas chosen from the group consisting of methane and ethylene,
- (ii) nitrogen;
- and
- (iii) a condensable gas that has a boiling point at least about 40.degree. C. above the boiling point of said hydrocarbon gas at atmospheric pressure;
- (c) withdrawing from said permeate side a permeate stream enriched in said hydrocarbon gas and said condensable gas compared with said gas mixture;
- (d) withdrawing from said feed side a residue stream enriched in said nitrogen compared with said gas mixture.
9 more elements
A gas-separation process comprising:
- (a) providing a membrane having a feed side and a permeate side;
- said membrane comprising a polymer material characterized by:
- (i) a glass transition temperature, T.sub.g, of at least about 100.degree. C.,
- (ii) a free volume V.sub.F of at least about 10%, and
- (iii) a methane permeability at room temperature of at least about 1,000 Barrer;
- (b) contacting said feed side with a gas mixture comprising:
- (i) a hydrocarbon gas chosen from the group consisting of methane and ethylene,
- (ii) nitrogen;
- and
- (iii) a condensable gas that has a boiling point at least about 40.degree. C. above the boiling point of said hydrocarbon gas at atmospheric pressure;
- (c) withdrawing from said permeate side a permeate stream enriched in said hydrocarbon gas and said condensable gas compared with said gas mixture;
- (d) withdrawing from said feed side a residue stream enriched in said nitrogen compared with said gas mixture;
- said process being characterized in that said membrane, when in use in said process, exhibits a hydrocarbon gas/nitrogen selectivity of at least about 4.
10 more elements
Dependencies are inferred from the claim text.