Compact Membrane Systems, Inc.

Dupont Canada Inc.

Cms Technologies Holdings, Inc.

Cps Technology Holdings LLC

E.i. Dupont De Nemours and Company

Kansas State University Research Foundation

Stuart Marshall Nemser

Ian Charles Roman

Sudipto Majumdar

Andrew Edward Feiring

Kenneth J Pennisi

Jay Olpin

Kevin Patrick Callaghan

Edward G Howard

David Neil Marks

Daniel Campos

John J Bowser

Ning Shangguan

George Alfred Cragg

Louis Himelreich

Nicholas Farkas

Todd Colin Reppert

Mary E Rezac

Praveen Kosaraju

This invention discloses a thin-film composite membrane and process for the separation of carbon dioxide from non-hydrophilic gases such as methane, hydrogen, and nitrogen. The thin-film composite membrane has a gas-separation layer and a nonporous high-diffusion-rate layer, and has carbon dioxide to non-hydrophilic gas selectivity that is greater than the intrinsic selectivity of the gas-separation layer alone.

Carbon dioxide separation membranes and process

A membrane separation process using a highly fluorinated polymer membrane that selectively permeates water of an aqueous ionic liquid solution to provide dry ionic liquid. Preferably the polymer is a polymer that includes polymerized perfluoro-2,2-dimethyl-1,3-dioxole (PDD). The process is also capable of removing small molecular compounds such as organic solvents that can be present in the solution. This membrane separation process is suitable for drying the aqueous ionic liquid byproduct from precipitating solutions of biomass dissolved in ionic liquid, and is thus instrumental to providing usable lignocellulosic products for energy consumption and other industrial uses in an environmentally benign manner.

Membrane separation of ionic liquid solutions

Separation of the components of liquid mixtures is achieved by contacting a liquid mixture with a nonporous membrane having a fluoropolymer selectively permeable layer and imposing a pressure gradient across the membrane from feed side to permeate side. Unusually high transmembrane flux is obtained when the membrane is subjected to one or more process conditions prior to separation. These include (a) leaving some residual amount of membrane casting solvent in the membrane, and (b) contacting the membrane with a component of the mixture to be separated for a duration effective to saturate the membrane with the component.

Organic fluid permeation through fluoropolymer membranes

A method of removing water from fluid mixtures of the water with other compounds uses selective vapor permeation or pervaporation of the water, as the case may be, from the mixture through a membrane having an amorphous perfluoropolymer selectively permeable layer. The novel process can be applied in such exemplary embodiments as (a) removing water from mixtures of compounds that have relative volatility of about 1-1.1 or that form azeotropic mixtures with water, (b) the dehydration of hydrocarbon oil such as hydraulic fluid to concentrations of water less than about 50 ppm, (c) removing water byproduct of reversible chemical equilibrium reactions to favor high conversion of reactants to desirable products, (d) drying ethanol to less than 0.5 wt. % water as can be used in fuel for internal combustion engines, and (e) controlling the water content to optimum concentration in enzyme-catalyzed chemical reactions carried out in organic media.

Removal of water from fluids

A method of removing water and/or methanol from fluid mixtures of the water or methanol with other compounds uses vapor permeation or pervaporation of the water or methanol, as the case may be, from the mixture through a membrane having an amorphous perfluoropolymer selectively permeable layer. The novel process can be applied in such exemplary embodiments as (a) removing water or methanol from mixtures of compounds that have relative volatility of about 1-1.1 or that form azeotropic mixtures with water or methanol, (b) the dehydration of hydrocarbon oil such as hydraulic fluid to concentrations of water less than about 50 ppm, (c) removing water and methanol byproducts of reversible chemical reactions thereby shifting equilibrium to favor high conversion of reactants to desirable products, (d) drying ethanol to less than 0.5 wt. % water as can be used in fuel for internal combustion engines, and (e) controlling the water content to optimum concentration in enzyme-catalyzed chemical reactions carried out in organic media.

Removal of water and methanol from fluids

A method of increasing the rate of conversion of reactants to reaction product of enzyme catalyzed, reversible, i.e., equilibrium, reactions having water or methanol as byproduct includes removing water and/or methanol from the reaction mass during reaction by permeation of the reaction mass through a selectively permeable perfluorinated polymer or copolymer membrane.

Increasing rate of enzyme catalyzed equilibrium reactions

A cyclic process for controlling environmental emissions of volatile organic compounds (VOC) from vapor recovery in storage and dispensing operations of liquids maintains a vacuum in the storage tank ullage. In the first part of a two-part cyclic process ullage vapor is discharged through a vapor recovery system in which VOC are stripped from vented gas with a selectively gas permeable membrane. In the second part, the membrane is inoperative while gas pressure rises in the ullage. In one aspect of this invention, a vacuum is drawn in the membrane separation unit thus reducing overall VOC emissions.

Cyclic membrane separation process

A membrane separation process and apparatus for carrying out the process involves contacting a gas feed mixture with one side of a selectively gas permeable membrane and allowing the components to pass through the membrane to form a permeate composition in contact with the opposite side of the membrane and leave a retentate composition on the feed side of the membrane. The process includes introducing a sweep flow of feed gas into the permeate composition near the membrane at a rate effective to increase the enrichment of the retentate composition in the less preferentially permeable component of the feed mixture to a concentration much greater than is achieved without the sweep flow. This process is especially well suited to improve single stage membrane separation effectiveness so that the need for conventional multistage separations to achieve moderate to high purity retentate compositions can be obviated. The novel process is particularly useful for providing enriched air in the concentration range of 80-90 vol. % nitrogen.

Method of producing nitrogen enriched air

A filter useful for the ultrafiltration and microfiltration of aqueous suspensions includes a microporous membrane structure that has pores of size effective to reject particles in the range of about 0.01-10 &mgr;m. At least a portion of the membrane structure in contact with the suspension has a surface energy less than that of polytetrafluoroethylene. Low surface energy can be achieved by coating a microporous substrate with a substance such as fluorine substituted dioxole polymer. The filter has superior resistance to fouling by species suspended in the aqueous suspension and can continuously filter flow of such suspension in excess of 100 L/(m,&minus;h) for more than 150 hours. The new filter is useful in many traditionally fouling prone ultrafiltration and microfiltration membrane applications such as the filtering of shipboard generated graywater waste.

Dioxole coated membrane module for ultrafiltration or microfiltration of aqueous suspensions

A portable breathing air supply apparatus uses a membrane separation module to obtain oxygen enriched air from ambient air which is blown into the module by an electrically powered fan. Oxygen enriched air is withdrawn from the permeate side of the membrane by a vacuum pump and is stored in a reservoir while the user exhales. In a preferred mode, a conserver valve in a tube leading from the reservoir to the user's mouth or nose is triggered to feed the enriched air for a preselected duration after a sensor in the tube detects onset of inhalation. Power for the electrical components can be supplied by batteries. The portable apparatus is sufficiently compact and light to be transported by persons weakened by certain chronic breathing disorders, such as chronic obstructive pulmonary disease and emphysema, and thus frees the user to roam for long periods away from a primary source of oxygen.

Oxygen enriched air supply apparatus

A novel method of operating an internal combustion engine employs a selectively gas permeable membrane to provide either oxygen or nitrogen enriched air feed to beneficially affect engine performance. By feeding enriched air from a membrane unit such performance parameters as reduced NOx emissions, lean burn limit, engine power, and reduced cold start emissions can be enhanced relative to feeding ambient air. The selectively gas permeable membrane unit further includes a nonporous membrane (i) having an oxygen/nitrogen selectivity of at least 1.4 and a permeability to oxygen of at least 50 barrers; (ii) formed from an amorphous copolymer of perfluoro-2,2-dimethyl-1,3-dioxole; and (iii) being at a temperature below the glass transition temperature of the amorphous copolymer. A cylindrical module having many substantially parallel aligned small diameter hollow fiber membrane structures is ideally suited for carrying out the novel method. The apparatus can be configured to furnish only one of permeate fraction, oxygen enriched air or retentate fraction, nitrogen enriched air. Additionally, the apparatus can be configured to switch between oxygen and nitrogen enrichment modes.

Combustion engine air supply system

A process for placing an ultra thin layer of a non-porous gas permeable polymer continuously over an entire filter surface area allows the fabrication of compact, high flux, fouling resistant gas filters. The process involves contacting a dilute coating solution of gas permeable polymer in a solvent with one side of a microporous substrate. The pore size of the substrate is chosen for its ability to effectively filter the gas permeable polymer from the coating solution. Solvent of the coating solution is made to flow through the microporous substrate which causes an ultra thin layer of polymer to build up on the side of substrate. When a desired thickness of polymer is built up, the solution and solvent is removed and residual solvent is evaporated, preferably by passing a gas at high rate over the surface of the polymer layer. This process can be used to coat flat sheet and hollow fiber substrates. The process is particularly useful for coating multiple hollow fibers assembled in modules which by virtue of the high surface area density of small diameter fibers and the efficient packing of many fibers in the modules, provide very high filter surface area in a small volume. The coated fiber modules thus can be used as high flow rate gas filters in applications such as filtering nuisance particules from recovered gas streams, collecting hazardous or valuable droplets suspended in a gas process stream for protection or salvage. Specific applications include filtering air for microelectronic circuit assembly facilities and filtering microbes from the atmosphere in biomedical 'clean rooms'. A preferred gas permeable polymer for use with this invention is an amorphous copolymer of perfluoro-2,2-dimethyl-1,3-dioxole. The superior hydrophobicity and oleophobicity of this material in the form of a non-porous, continuous layer provides a barrier for solid particles and liquid droplets from blocking flow through a gas filter. Furthermore, a gas filter made according to this invention can be easily cleaned and restored to near-original gas flux performance.

Non-porous gas permeable membrane

A method of adding or removing a gas to or from a solution of the gas in a liquid involves transferring the gas between the liquid and another fluid through a membrane unit. The membrane unit includes a membrane which is (i) substantially impermeable to the solvent and having a permeability to oxygen of at least 100 barrers; (ii) formed from an amorphous copolymer of perfluoro-2,2-dimethyl-1,3-dioxole; and (iii) is maintained at a temperature below the glass transition temperature of the copolymer. The fluid can be another liquid or a gas. The novel method provides very high rates of gas transmission between liquids and permits gasifying liquids without resort to sparging bubbles through the liquid. The method thus can gasify liquid with superior efficiency and without excessive agitation due to bubbling. These features result in economy of gas consumption and reduced need for gas recovery equipment, and when used in connection with a toxic or organic gaseous component, reduced requirements for additional pollution control equipment. The membrane material is resistant to fouling by liquids, and especially, by bioreactor mass. Hence, the novel method can remain in service for long duration without substantially diminished performance. Utilities for the novel method include purifying drinking water through ozonolysis, oxygenating bioreactors and blood; oxidizing volatile organic compounds in water; adding gaseous reactants to liquid chemical reactions and supplying oxygen to and removing volatile pollutants from waste water.

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Wilmington, DE, United States of America

Stuart Marshall Nemser