Acid tolerant polymeric membrane and process for the recovery of acid using polymeric membranes
AssigneeExxonMobil Research and Engineering Company
InventorsBhupender S. Minhas, Dennis G. Peiffer, Michael Mayers, Lloyd S. White, William A. Feehley
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Abstract
A multi-layer membrane structure including a crosslinked polymeric membrane, such as a crosslinked polyvinyl sulfate membrane or a crosslinked copolymer polyvinyl sulfate and polyvinyl alcohol membrane, is provided. The membrane structure is suitable for use in an acid environment, and is suitable for recovering acid from a feed mixture comprising acid, hydrocarbons and water.
Claims14
A multi-layer membrane structure for use in acid environments, comprising:
- a first layer composed of a crosslinked polymeric membrane comprising a copolymer of crosslinked polyvinyl alcohol and, polyvinyl sulfate, such membrane having a first thickness, the membrane being selectively permeable to acid over hydrocarbons and further characterized as having a crosslink density from about 3.0% to about 15.0%, and wherein the crosslinked polymeric membrane is crosslinked utilizing a crosslinking agent selected from the group consisting of 1,4 diisocyanatohexane, 1,4 diisocyanatobutane, 1,8 diisocyanatooctane, 1,12 diisocyanatododecane, 1,5 diisocyanato-2-methyl pentane, and 4,4′ diisocyanato-diphenylmethane;
- a second layer composed of a fluoropolymer or a cellulosic polymer having a pore size that is less than half of the first thickness;
- and
- a third structural layer composed of a material with a pore size of at least 3 μm, an intrinsic bulk material value for the flexural modulus of greater than about 100×103 psi, and an intrinsic bulk material value for the tensile modulus of greater than about 10,000 psi.
A multi-layer membrane structure for use in acid environments having 70% or more by weight of acid, consisting essentially of:
- a first layer composed of a crosslinked polymeric membrane comprising a copolymer of crosslinked polyvinyl alcohol and polyvinyl sulfate, such membrane having a first thickness, the membrane being selectively permeable to acid over hydrocarbons and further characterized as having a crosslink density from about 3.0% to about 15.0%, and wherein the crosslinked polymeric membrane is crosslinked utilizing a crosslinking agent selected from the group consisting of 1,4 diisocyanatohexane, 1,4 diisocyanatobutane, 1,8 diisocyanatooctane, 1,12 diisocyanatododecane, 1,5 diisocyanato-2-methyl pentane, and 4,4′ diisocyanato-diphenylmethane;
- a second layer composed of a fluoropolymer or a cellulosic polymer having a pore size that is less than half of the first thickness, the second layer having a first volumetric change value in sulfuric acid;
- and
- a third structural layer composed of a material with a pore size of at least 3 μm, an intrinsic bulk material value for the flexural modulus of greater than about 100×103 psi, an intrinsic bulk material value for the tensile modulus of greater than about 10,000.
Dependencies are inferred from the claim text.