Nitrogen gas separation using organic-vapor-resistant membranes
AssigneeMembrane Technology and Research, Inc.
InventorsRichard W. Baker, Ingo Pinnau, Zhenjie He, Karl D. Amo, Andre R. Da Costa, Ramin Daniels
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Abstract
A process for separating nitrogen from a multicomponent gas mixture containing nitrogen and a hydrocarbon, such as natural gas or associated gas, using gas-separation membranes selective for nitrogen over the hydrocarbon. The membranes use a selective layer made from a polymer having repeating units of a fluorinated polymer, and demonstrate good resistance to plasticization by the organic components in the gas mixture under treatment, and good recovery after exposure to liquid aromatic hydrocarbons.
Claims56
A process for separating nitrogen from a multicomponent gas mixture comprising nitrogen, a gaseous hydrocarbon and at least one other gaseous component, the process comprising the steps of:
- (a) bringing the gas mixture into contact with the feed side of a separation membrane having a feed side and a permeate side, the separation membrane having a selective layer comprising:
- a polymer comprising repeating units having a fluorinated cyclic structure of an at least 5-member ring, the polymer having a fractional free volume no greater than about 0.3;
- (b) providing a driving force for transmembrane permeation;
- (c) withdrawing from the permeate side a permeate stream enriched in nitrogen compared to the gas mixture;
- (d) withdrawing from the feed side a residue stream depleted in nitrogen compared to the gas mixture.
A process for separating nitrogen from a multicomponent gas mixture comprising nitrogen, a gaseous hydrocarbon and at least one other gaseous component, the process comprising the steps of:
- (a) bringing the gas mixture into contact with the feed side of a separation membrane having a feed side and a permeate side, the separation membrane having a selective layer comprising a polymer having:
- (i) a ratio of fluorine to carbon atoms in the polymer greater than 1:1;
- (ii) a fractional free volume no greater than about 0.3;
- and
- (iii) a glass transition temperature of at least about 100° C.;
- and the separation membrane being characterized by a post-exposure selectivity for nitrogen over the gaseous hydrocarbon, after exposure of the separation membrane to liquid toluene and subsequent drying, that is at least about 65% of a pre-exposure selectivity for nitrogen over the gaseous hydrocarbon, as measured pre- and post-exposure with a test gas mixture of the same composition and under like conditions;
- (b) providing a driving force for transmembrane permeation;
- (c) withdrawing from the permeate side a permeate stream enriched in nitrogen compared to the gas mixture;
- (d) withdrawing from the feed side a residue stream depleted in nitrogen compared to the gas mixture.
Dependencies are inferred from the claim text.