skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Mixed-conducting membranes for hydrogen production and separation.

Abstract

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) because of SFC's high combined electronic and ionic conductivities. We have evaluated extruded tubes of SFC for conversion of methane to syngas in a reactor that was operated at {approx}900 C. Methane conversion efficiencies were >90%, 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.more » 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, {approx}32 cm3(STP)/min-cm2, was measured at 900 C for an {approx}15-{micro}m-thick membrane on a porous support structure when 100% H2 at ambient pressure was used as the feed gas.« less

Authors:
; ; ; ; ; ;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
FE
OSTI Identifier:
972996
Report Number(s):
ANL/ES/CP-58002
TRN: US201005%%493
DOE Contract Number:
DE-AC02-06CH11357
Resource Type:
Conference
Resource Relation:
Conference: 2006 Materials Research Society Fall Meeting; Nov. 27, 2006 - Dec. 1, 2006; Boston, MA
Country of Publication:
United States
Language:
ENGLISH
Subject:
08 HYDROGEN; 01 COAL, LIGNITE, AND PEAT; 03 NATURAL GAS; 30 DIRECT ENERGY CONVERSION; CERAMICS; CERMETS; CHARGE CARRIERS; COAL GASIFICATION; FUEL CELLS; GASES; HYDROGEN; HYDROGEN PRODUCTION; MEMBRANES; METHANE; MIXTURES; OXIDATION; OXIDES; OXYGEN; PERMEABILITY; POROSITY; THICKNESS

Citation Formats

Balachandran, U., Ma, B., Lee, T. H., Song, S. J., Chen, L., Dorris, S. E., and Energy Systems. Mixed-conducting membranes for hydrogen production and separation.. United States: N. p., 2007. Web.
Balachandran, U., Ma, B., Lee, T. H., Song, S. J., Chen, L., Dorris, S. E., & Energy Systems. Mixed-conducting membranes for hydrogen production and separation.. United States.
Balachandran, U., Ma, B., Lee, T. H., Song, S. J., Chen, L., Dorris, S. E., and Energy Systems. Mon . "Mixed-conducting membranes for hydrogen production and separation.". United States. doi:.
@article{osti_972996,
title = {Mixed-conducting membranes for hydrogen production and separation.},
author = {Balachandran, U. and Ma, B. and Lee, T. H. and Song, S. J. and Chen, L. and Dorris, S. E. and Energy Systems},
abstractNote = {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) because of SFC's high combined electronic and ionic conductivities. We have evaluated extruded tubes of SFC for conversion of methane to syngas in a reactor that was operated at {approx}900 C. Methane conversion efficiencies were >90%, 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, {approx}32 cm3(STP)/min-cm2, was measured at 900 C for an {approx}15-{micro}m-thick membrane on a porous support structure when 100% H2 at ambient pressure was used as the feed gas.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}

Conference:
Other availability
Please see Document Availability for additional information on obtaining the full-text document. Library patrons may search WorldCat to identify libraries that hold this conference proceeding.

Save / Share:
  • The electronic transference numbers of BCY were relatively low when compared with the protonic numbers. At 800 C, a hydrogen flux of only 0.02 cm{sup 3}/min/cm{sup 2} was obtained in an {approx} 2-rnm-thick BCY sample by short-circuiting the two Pt electrodes. We have developed a novel composite system with improved electronic transport, and preliminary measurements indicate that the new membrane materials can be used in a nongalvanic mode to separate hydrogen from gas mixtures. A maximum flux of 0.12 cm{sup 3}/min/cm{sup 2} has been measured at 800 C in the composite material operated in the nongalvanic mode. Currently, work ismore » underway to further enhance the hydrogen flux in the composite membrane materials.« less
  • SrCeO{sub 3}- and BaCeO{sub 3}-based proton conductors have been prepared and their transport properties have been investigated by impedance spectroscopy in conjunction with open circuit voltage and water vapor evolution measurements. BaCe{sub 0.8}Y{sub 0.2}O{sub 3-{delta}} exhibits the highest conductivity in a hydrogen-containing atmosphere; however, its electronic conductivity is not adequate for hydrogen separation in a nongalvanic mode. In an effort to enhance ambipolar conductivity and improve interfacial catalytic properties, BaCe{sub 0.8}Y{sub 0.2}O{sub 3-{delta}} cermets have been fabricated into membranes. The effects of ambipolar conductivity, membrane thickness, and interfacial resistance on permeation rates have been investigated. In particular, the significance ofmore » interfacial resistance is emphasized.« less
  • The Office of Fossil Energy of the U.S. Department of Energy is formulating ``Vision 21,'' a program aimed at developing technologies for highly efficient power and coproduction plants that discharge almost no pollutants and close the carbon cycle. An integrated gasification combined cycle (IGCC) system is a likely modular component of a Vision 21 coproduction plant. IGCC technology is ideally suited for the coproduction of electricity and high-quality transportation fuel and/or a host of high-value chemicals. As part of the IGCC system, high-temperature membranes for separating hydrogen from coal gasification and other partial-oxidation product streams are being considered. Thin andmore » dense ceramic membranes fabricated from mixed protonic and electronic conductors provide a simple, efficient means for separating hydrogen from gas streams. Dense mixed-conducting ceramic membranes effect transport via ion- and electron-conducting mechanisms. Because these membranes have no interconnected porosity, selectivity for hydrogen is nearly 100%. Hydrogen separation is achieved in a nongalvanic mode, i.e., without the need for electrodes and external power supply to drive the separation. BaCeO{sub 3}-based materials exhibit protonic conductivity that is significantly higher than its electronic conductivity. To enhance the electronic conductivity and increase hydrogen permeation, the authors have fabricated BaCeO{sub 3}-containing cermet membranes and used them in a nongalvanic mode to separate hydrogen from gas streams containing H{sub 2}, CO, CO{sub 2}, and trace amounts of H{sub 2}S. Material selection, fabrication, performance as well as technical/technological challenges of the ceramic membranes for hydrogen separation are discussed in this talk.« less
  • Hydrogen production from water splitting at high temperatures has been studied with novel mixed oxygen ion-electron conducting cermet membranes. Hydrogen production rates were investigated as a function of temperature, water partial pressure, membrane thickness, and oxygen chemical potential gradient across the membranes. The hydrogen production rate increased with both increasing moisture concentration and oxygen chemical potential gradient across the membranes. A maximum hydrogen production rate of 4.4 cm{sup 3}/min-cm{sup 2} (STP) was obtained with a 0.10-mm-thick membrane at 900 C in a gas containing 50 vol.% water vapor in the sweep side. Hydrogen production rate also increased with decreasing membranemore » thickness, but surface kinetics play an important role as membrane thickness decreases.« less
  • Non-perovskite SrFeCo{sub 0.5}O{sub x} (SFC2) was found to have high electronic and ionic conductivities as well as structural stability. At 800 C in air, total and ionic conductivities of 17 and 7 S{center_dot}cm{sup -1} were measured, respectively; the ionic transference number was calculated to be {approx}0.4. This material is unique because of its high electronic conductivity and comparable electronic and ionic transference numbers. X-ray diffraction analysis showed that air-sintered SFC2 consists of three phase components, {approx}75 wt% Sr{sub 4}(Fe{sub 1-x}Co{sub x}){sub 6}O{sub 13 {+-}{delta}}, {approx}20 wt% perovskite Sr(Fe{sub 1-x}Co{sub x}O{sub 3-{delta}}), and {approx}5 wt% rock salt CoO. Argon-annealed SFC2 containsmore » brownmillerite Sr{sub 2}(Fe{sub 1-x}Co{sub x}){sub 2}O{sub 5} and rock salt CoO. Dense SFC2 membranes were able to withstand large pO{sub 2} gradients and retain mechanical strength. A 2.9-mm-thick disk membrane was tested in a gas-tight electrochemical cell at 900 C; an oxygen permeation flux rate {approx}2.5 cm{sup 3}(STP){center_dot}cm{sup -2}{center_dot}min{sup -1} was measured. A dense thin-wall tubular membrane of 0.75-mm thickness was tested in a methane conversion reactor for over 1,000 h. At 950 C, the oxygen permeation flux rate was {approx}10 cm{sup 3}(STP){center_dot}cm{sup -2}{center_dot}min{sup -1} when the SFC2 thin-wall membrane was exposed with one side to air and the other side to 80% methane balanced with inert gas. Results from these two independent experiments agreed well. The SFC2 material is a good candidate as dense ceramic membranes for oxygen separation from air or for use in methane conversion reactors.« less