The Thickness Dependence of Oxygen Permeability in Sol-Gel Derived Ce0.8Gd0.2O2-δ-CoFe2O4 Thin Films on Porous Ceramic Substrates: A Sputtered “Blocking Layer” for Thickness Control

2008 ◽  
Vol 1126 ◽  
Author(s):  
Kyle S. Brinkman ◽  
Takashi Iijima ◽  
Hitoshi Takamura
Keyword(s):  
Thin Film ◽  
Porous Ceramic ◽  
Sol Gel ◽  
Electronic Conductivity ◽  
Composite Membranes ◽  
Ceramic Membranes ◽  
Oxygen Flux ◽  
Membrane Thickness ◽  
Ceramic Substrates ◽  
Oxidation Of Methane

AbstractMixed conductive oxides are a topic of interest for applications in oxygen separation membranes as well as use in producing hydrogen fuel through the partial oxidation of methane. The oxygen flux through the membranes is governed both by the oxygen ionic conductivity as well as the material's electronic conductivity; composite membranes like Ce0.8Gd0.2O2-δ(CGO)-CoFe2O4 (CFO) use gadolinium doped ceria oxides as the ionic conducting material combined with cobalt iron spinel which serves as the electronic conductor. In this study we employ ˜ 50 nm sputtered CeO2 layers on the surface of porous CGO ceramic substrates which serve as solution ‘blocking’ layers during the thin film fabrication process facilitating the control of film thickness. Films with thickness of ˜ 2 and 4 microns were prepared by depositing 40 and 95 separate sol-gel layers respectively. Oxygen flux measurements indicated that the permeation increased with decreasing membrane thickness; thin film membrane with thickness on the micron level showed flux values an order of magnitude greater (0.03μmol/cm2 s) at 800oC as compared to 1mm thick bulk ceramic membranes (0.003 μmol/cm2).

Development of Mixed-Counducting Ceramics For Gas Separation Applications

1998 ◽  
Vol 548 ◽  
Author(s):  
U. Balachandran ◽  
B. Ma ◽  
P.S. Maiya ◽  
J.T. Dusek ◽  
J.J. Picciolo ◽  
...  
Keyword(s):  
Gas Separation ◽  
Hydrogen Permeation ◽  
Electronic Conductivity ◽  
Ionic Conductivities ◽  
Ceramic Membranes ◽  
Oxygen Flux ◽  
Membrane Thickness ◽  
Conducting Oxides ◽  
Separation Membranes ◽  
Oxidation Of Methane

ABSTRACTMixed-conducting oxides are used in many applications, including fuel cells, gas separation membranes, sesors, and electrocatalysis. This paper describes mixed-conducting ceramic membranes that are being developed to selectively remove oxygen and hydrogen from gas streams in a nongalvanic mode of operation (i.e., with no electrodes or external power supply). Because of its high combined electronic/ionic conductivity and significant oxygen permeability, the mixed-coducting Sr-Fe-Co oxide (SFC) has been developed for high-purity oxygen separation and/or partial oxidation of methane to synthesis gas, i.e., syngas, a mixture of carbon monoxide and hydorgen. The electronic and ionic conductivities of SFC were found to be comparable in magnitude are presented as a function of temperature. The oxygen flux through dense SFC tubes during separation of oxygen from air is compared with the oxygen flux during methane conversion.Unlike SFC, in which the ionic and electronic conductivities are nearly equivalent, BaCe0.80Y0.20O3 (BCY) exhibits protonic conductivity that is significantly higher that its electronic coductivity. To enhance the electronic conductivity and increase hydrogen permeation, metal powder was combined with the BCY to form a cermet membrane. Nongalvanic permeation of hydrogen through the cermet memebrane was demonstrated and characterized as a function of membrane thickness. A sintering aid was developed to avoid interconnected porosity in and improve the mechanical properties of the cermet membrane.

Nafion/PBI Nanofiber Composite Membranes for Fuel Cells Applications

2010 ◽  
Author(s):  
Tzyy-Lung Leon Yu ◽  
Shih-Hao Liu ◽  
Hsiu-Li Lin ◽  
Po-Hao Su
Keyword(s):  
Thin Film ◽  
Fuel Cell ◽  
Composite Membrane ◽  
Fiber Composite ◽  
Composite Membranes ◽  
Cell Performance ◽  
Membrane Electrode ◽  
Membrane Thickness ◽  
Fuel Cell Performance ◽  
Nano Fiber

The PBI (poly(benzimidazole)) nano-fiber thin film with thickness of 18–30 μm is prepared by electro-spinning from a 20 wt% PBI/DMAc (N, N′-dimethyl acetamide) solution. The PBI nano-fiber thin film is then treated with a glutaraldehyde liquid for 24h at room temperature to proceed chemical crosslink reaction. The crosslink PBI nano-fiber thin film is then immersed in Nafion solutions to prepare Nafion/PBI nano-fiber composite membranes (thickness 22–34 μm). The morphology of the composite membranes is observed using a scanning electron microscope (SEM). The mechanical properties, conductivity, and unit fuel cell performance of membrane electrode assembly (MEA) of the composite membrane are investigated and compared with those of Nafion-212 membrane (thickness ∼50 μm) and Nafion/porous PTFE (poly(tetrafluoro ethylene)) composite membrane (thickness ∼22 μm). We show the present composite membrane has a similar fuel cell performance to Nafion/PTFE and a better fuel cell performance than Du Pont Nafion-212.

Mixed-Conducting Membranes for Hydrogen Production and Separation

2006 ◽  
Vol 972 ◽  
Author(s):  
U. Balachandran ◽  
Beihai Ma ◽  
Tae H Lee ◽  
Sun-Ju Song ◽  
Ling Chen ◽  
...  
Keyword(s):  
Ambient Pressure ◽  
Hydrogen Permeability ◽  
Composite Membranes ◽  
Ceramic Membranes ◽  
Electronic Charge ◽  
Membrane Thickness ◽  
Pure Hydrogen ◽  
Metal Composite ◽  
Proton Conducting ◽  
Conducting Oxides

AbstractMixed-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 ≈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, ≈32 cm3(STP)/min-cm2, was measured at 900°C for an ≈15-μm-thick membrane on a porous support structure when 100% H2 at ambient pressure was used as the feed gas.

scholarly journals Synthesis and characterization of Fe(III)-doped ceramic membranes of titanium dioxide and its application in photoelectrocatalysis of a textile dye

2017 ◽  
Vol 36 (1) ◽  
pp. 18
Author(s):  
Emanuel C. Rodrigues ◽  
Layciane A. Soares ◽  
Marco A. Modenes Jr. ◽  
Jeosadaque J. Sene ◽  
Gilbert Bannach ◽  
...  
Keyword(s):  
Thin Film ◽  
Sol Gel ◽  
Ceramic Membranes ◽  
Titanium Isopropoxide ◽  
Textile Dye ◽  
Doped Tio2 ◽  
Precursor Material ◽  
Thin Film Electrodes ◽  
Nanocrystalline Anatase Tio2

Pure and Fe(III)-doped TiO2 suspensions were prepared by the sol gel method with the use of titanium isopropoxide (Ti(OPri)4) as precursor material. The properties of doped materials were compared to TiO2 properties based on the characterization by thermal analysis (TG-DTA and DSC), X-ray powder diffractometry and spectroscopy measurements (FTIR). Both undoped and doped TiO2 suspensions were used to coat metallic substrate as a mean to make thin-film electrodes. Thermal treatment of the precursors at 400°C for 2 h in air resulted in the formation of nanocrystalline anatase TiO2. The thin-film electrodes were tested with respect to their photocatalytic performance for degradation of a textile dye in aqueous solution. The plain TiO2 remains as the best catalyst at the conditions used in this report.

scholarly journals Fabrication and Characterization of Ice Templated Membrane Supports from Portland Cement

Membranes ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 93
Author(s):  
Amanmyrat Abdullayev ◽  
Paul H. Kamm ◽  
Maged F. Bekheet ◽  
Aleksander Gurlo
Keyword(s):  
High Temperature ◽  
Portland Cement ◽  
Ceramic Membrane ◽  
Porous Ceramic ◽  
Ceramic Membranes ◽  
Fabrication Process ◽  
Transmembrane Pressure ◽  
Hydration Reaction ◽  
Membrane Thickness ◽  
Membrane Fabrication

Porous ceramic membranes for aqueous microfiltration and ultrafiltration processes suffer from the high-costs of material and processing. The latter is mainly due to the high-temperature sintering step. In this work, cement-based membrane supports from ultrafine Portland cement are studied as a low-cost alternative to traditional oxidic ceramic supports. An environmentally friendly freeze-casting fabrication route is applied for the fabrication of porous membrane supports. Cement membrane supports are becoming mechanically stabile after hydration reaction of cement with water, which does not require any high-temperature sintering step as in a conventional ceramic membrane fabrication process. This fabrication route, which is sintering-free, decreases the cost and environmental impact of the membrane fabrication process by eliminating extra energy consumption step during sintering. The Archimedes method, scanning electron microscopy (SEM), micro-computed tomographic (µCT), and mercury porosimetry characterize the membrane supports in respect to open porosity, pore size distribution, morphology, and connectivity. The flexural strength of the 3 mm thick membranes is in the range from 1 to 6 MPa, as obtained by the ring-on-ring tests. The obtained membrane supports possess porosity in the range between 48 and 73% depending on fabrication conditions (cooling rate and the solid content, as determined by Archimedes method enabling water flux in the range between 79 and 180 L/(h·m2) at 0.5 bar transmembrane pressure difference and 3 mm membrane thickness.

scholarly journals Synthesis and characterization of Fe(III)-doped ceramic membranes of titanium dioxide and its application in photoelectrocatalysis of a textile dye

2011 ◽  
Vol 36 (1) ◽  
pp. 18-36 ◽  
Author(s):  
Emanuel C. Rodrigues ◽  
Layciane. A. Soares ◽  
Marco A. Modenes Jr ◽  
Jeosadaque J. Sene ◽  
Gilbert Bannach ◽  
...  
Keyword(s):  
Thin Film ◽  
Sol Gel ◽  
Ceramic Membranes ◽  
Titanium Isopropoxide ◽  
Textile Dye ◽  
Doped Tio2 ◽  
Precursor Material ◽  
Thin Film Electrodes ◽  
Nanocrystalline Anatase Tio2

Pure and Fe(III)-doped TiO2 suspensions were prepared by the sol gel method with the use of titanium isopropoxide (Ti(OPri)4) as precursor material. The properties of doped materials were compared to TiO2 properties based on the characterization by thermal analysis (TG-DTA and DSC), X-ray powder diffractometry and spectroscopy measurements (FTIR). Both undoped and doped TiO2 suspensions were used to coat metallic substrate as a mean to make thin-film electrodes. Thermal treatment of the precursors at 400ºC for 2 h in air resulted in the formation of nanocrystalline anatase TiO2. The thin-film electrodes were tested with respect to their photocatalytic performance for degradation of a textile dye in aqueous solution. The plain TiO2 remains as the best catalyst at the conditions used in this report.

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