Ballard Power Systems Corporation

Chemetics Inc.

David Alexander Summers

Charles Stone

Herwig Haas

Thomas S Drackett

Siamak Lashkari

Paul Darcy Kozak

Roza Tizvar

Jurgen Erich Hinze

Felix Man Fai Mok

A gaseous species can be separated from an aqueous donor mixture and absorbed in an aqueous recipient mixture using a membrane separation apparatus while maintaining a large temperature difference (e.g. greater than 30&#xb0; C.) between the two aqueous mixtures. A composite membrane is employed which comprises a non-porous membrane adjacent a porous membrane. The non-porous membrane is permeable to the gaseous species. The porous membrane has a porosity greater than 50% and is hydrophobic. In one embodiment, the composite membrane is oriented such that the porous membrane faces the aqueous recipient mixture and is impermeable thereto at the recipient mixture pressure. The invention is particularly suitable for separating chlorine dioxide from chlorine dioxide reaction liquor and absorbing in chilled water.

Membrane separation at high temperature differential

A fuel cell system is operated with the fuel supply pressure greater than the oxidant supply pressure to the fuel cell. This gives improved performance particularly when the fuel cell system is closed on the fuel side. The magnitude of fuel overpressure may be varied in accordance with variations in the fuel cell operating parameters.

Methods of operating fuel cells having closed reactant supply systems

A composite membrane for use in a fuel cell membrane electrode assembly comprises a porous polymeric substrate and an impregnant partially filling the substrate such that the substrate comprises a first region having pores substantially filled with the impregnant, and a second substantially porous region. The impregnant comprises a cation exchange material. The cation exchange material covers one surface of the substrate in a dense surface layer, contiguous with the first region of the substrate. The substrate has greater than 10% residual porosity, and the composite membrane is substantially gas impermeable and has at least one substantially porous major surface.

Composite ion exchange membrane for use in a fuel cell

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Vancouver, Canada

David Alexander Summers