Gas separation using C3+ hydrocarbon-resistant membranes
AssigneeMembrane Technology and Research, Inc.
InventorsIngo Pinnau, Zhenjie He, Andre R. Da Costa, Karl D. Amo, Ramin Daniels
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Abstract
A process for separating a gas from a gas mixture containing the gas and a C3+ hydrocarbon vapor, using gas-separation membranes selective for the gas over the C3+ hydrocarbon vapor. 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.
Claims47
A process for separating a desired gas from a gas mixture comprising the desired gas and a C3+ hydrocarbon vapor, the process comprising the steps of:
- (a) passing the gas mixture across 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 the desired gas over the C3+ hydrocarbon vapor, after exposure of the separation membrane to liquid toluene and subsequent drying, that is at least about 65% of a pre-exposure selectivity for the desired gas over the C3+ hydrocarbon vapor, 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 the desired gas compared to the gas mixture;
- (d) withdrawing from the feed side a residue stream depleted in the desired gas compared to the gas mixture.
A process for separating hydrogen from a gas mixture comprising hydrogen and a C3+ hydrocarbon vapor, the process comprising the steps of:
- (a) passing the gas mixture across 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 hydrogen over the C3+ hydrocarbon vapor, after exposure of the separation membrane to liquid toluene and subsequent drying, that is at least about 65% of a pre-exposure selectivity for hydrogen over the C3+ hydrocarbon vapor, 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 hydrogen compared to the gas mixture;
- (d) withdrawing from the feed side a residue stream depleted in hydrogen compared to the gas mixture.
A process for separating propylene from a gas mixture comprising propylene and propane, the process comprising the steps of:
- (a) passing a gas mixture comprising propylene and propane across 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 propylene over propane, after exposure of the separation membrane to liquid toluene and subsequent drying, that is at least about 65% of a pre-exposure selectivity for propylene over propane 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 propylene compared to the gas mixture;
- (d) withdrawing from the feed side a residue stream depleted in propylene compared to the gas mixture.
Dependencies are inferred from the claim text.