November 7, 2008
Friday, 11:30AM
15 Saint Mary's Street, Room 105 |
Dr. U. (Balu) Balachandran
Argonne National Laboratory
Development of Dense Membranes for Hydrogen Production and
Purification |
| Abstract:
The Office of Fossil Energy (FE) at the U.S. Department of Energy (DOE) sponsors a wide range of research, development, and demonstration programs to maximize the use of the vast domestic fossil resources and ensure a fuel-diverse energy sector while responding to global environmental concerns. Cost-effective, membrane-based reactor and separation technologies are of considerable interest to DOE-FE programs to develop advanced coal-based power and fuel technologies. Funded by DOE’s FE, Argonne is developing dense membranes for hydrogen production and separation from fossil resources.
Mixed-conducting oxides, possessing both ionic and electronic charge carriers, have found wide application in recent years in solid-state electrochemical devices that operate at high temperatures, e.g., solid-oxide fuel cells, batteries, and sensors. These materials also hold promise as dense ceramic membranes that separate gases such as oxygen and hydrogen from mixed-gas streams. We are developing Sr-Fe-Co oxide (SFC) as a membrane that selectively transports oxygen during partial oxidation of methane to syngas (mixture of CO and H2). We have evaluated extruded tubes of SFC for converting methane to syngas in a reactor that was operated at ≈900°C. Methane conversion efficiencies were >85%, and some of the reactor tubes were operated for >1000 h. We are also developing dense proton-conducting oxides to separate pure hydrogen from product streams that are generated during methane reforming and coal gasification. Hydrogen selectivity in these membranes is nearly 100%, because they are free of interconnected porosity. Although most studies of hydrogen separation membranes have focused on proton-conducting oxides by themselves, we have developed cermet (i.e., ceramic-metal composite) membranes in which metal powder is mixed with these oxides in order to increase their hydrogen permeability. Using several feed gas mixtures, we measured the nongalvanic hydrogen permeation rate, or flux, for the cermet membranes in the temperature range of 500-900°C. This rate varied linearly with the inverse of membrane thickness. The highest rate, ≈50 cm3(STP)/min-cm2, was measured at 900°C for an ≈20-um-thick membrane on a porous support structure when 100% H2 at ambient pressure was used as the feed gas. Hydrogen flux measurements in H2S-containing atmospheres showed that the cermet membranes are stable for up to 1200 h at 900°C in gases that contain 400 ppm H2S. The present status of membrane development at Argonne will be presented in this talk.
*Work supported by U.S. Department of Energy, Office of Fossil Energy, National Energy Technology Laboratory’s Hydrogen and Syngas Technologies Program
Bio:
Dr. Balachandran received Ph.D. in Materials Science in 1980. He has been doing research in the area of electronic materials for about 30 years. His current interests include ceramic membranes for gas separation, hydrogen production, and natural gas upgrading, fuel cells, high–temperature superconductors, and capacitors. He has been an invited speaker at numerous conferences in several countries. He is a Fellow of The American Ceramic Society, a Fellow of the Institute of Physics, and currently the Manager of Ceramics Section at Argonne National Laboratory. He has authored/coauthored more than 250 papers, edited 12 books, and holds 29 patents. He has won three R&D 100 Awards, two Federal Laboratory Consortium (FLC) Award for Excellence in Technology Transfer, two FLC Award of Merit, four Pacesetter Awards, three Director’s Awards, and University of Chicago’s Distinguished Performance Award (the highest honor offered at Argonne National Laboratory for scientific achievement).
|
