Membranes for Energy and Environmental Applications
Dr. Winston Ho
University of Kentucky
Department of Chemical Engineering
Monday, December 14, 2000 3:30pm
Ben Bandy Conference Center
Center for Applied Energy Research
This talk will cover three areas: (1) the removal and recovery of heavy metals from waste waters by supported liquid membranes (SLMs), (2) fuel-cell fuel processing with membranes, and (3) research opportunities on fuel cell membranes.
New membrane technology based on SLMs with strip dispersion for the removal and recovery of metals, including chromium, copper, zinc, and strontium, from waste waters and process streams has been developed. The technology not only removes the targeted metal in the treated effluent allowable for discharge or recycle, but also recovers the metal at high concentration and purity suitable for resale or reuse. In other words, the goals of zero discharge and no sludge have been achievable. The stability of the SLM has been ensured by a modified SLM with strip dispersion, where the aqueous strip solution is dispersed in the organic membrane solution in a mixer and the strip dispersion formed is circulated from the mixer to the membrane module to have a constant supply of the organic solution to the membrane pores.
New membranes for the removal of carbon dioxide from hydrogen-containing reformed gases have been synthesized by incorporating amines into polymeric networks. The membranes are selective to carbon dioxide preferentially versus hydrogen since carbon dioxide permeates through the amine-containing membranes via the facilitated transport mechanism due to its reaction with the amine. This type of membranes has the potential for fuel-cell fuel processing, including the use of the membranes both in the membrane reactor configuration to enhance water gas shift reaction and in the purification of hydrogen for the reformed gas generated from the partial oxidation of liquid fuel (e.g., gasoline and/or diesel).
We will discuss research opportunities on fuel cell membranes critical to widespread use of fuel cells, including proton-exchange membranes, cost-effective Nafion membrane replacements, membrane electrode assemblies (MEAs), and carbon monoxide-tolerant, platinum based catalysts in MEAs. Membranes for oxygen-enriched air (OEA) are also important for fuel cells as OEA can increase the hydrogen concentration in the reformed gas from partial oxidation and the performance of fuel cell on the cathode side. In addition, we will discuss the fuel cell related catalysis - improved catalysts for autothermal reforming and water gas shift reactions.