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Rune Bredesen - One of the best experts on this subject based on the ideXlab platform.
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New Insight to the Effects of Heat Treatment in Air on the Permeation Properties of Thin Pd77%Ag23% Membranes
Membranes, 2018Co-Authors: Nicla Vicinanza, Rune Bredesen, Thijs Peters, Ingeborg-helene Svenum, Hilde J. VenvikAbstract:Sputtered Pd77%Ag23% membranes of thickness 2.2–8.5 µm were subjected to a three-step heat treatment in air (HTA) to investigate the relation between thickness and the reported beneficial effects of HTA on Hydrogen transport. The permeability experiments were complimented by volumetric Hydrogen sorption measurements and atomic force microscopy (AFM) imaging in order to relate the observed effects to changes in Hydrogen solubility and/or structure. The results show that the HTA—essentially an oxidation-reduction cycle—mainly affects the thinner membranes, with the Hydrogen Flux increasing stepwise upon HTA of each membrane side. The Hydrogen solubility is found to remain constant upon HTA, and the change must therefore be attributed to improved transport kinetics. The HTA procedure appears to shift the transition from the surface to bulk-limited transport to lower thickness, roughly from ~5 to ≤2.2 µm under the conditions applied here. Although the surface topography results indicate that HTA influences the surface roughness and increases the effective membrane surface area, this cannot be the sole explanation for the observed Hydrogen Flux increase. This is because considerable surface roughening occurs during Hydrogen permeation (no HTA) as well, but not accompanied by the same Hydrogen Flux enhancement. The latter effect is particularly pronounced for thinner membranes, implying that the structural changes may be dependent on the magnitude of the Hydrogen Flux.
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on the high pressure performance of thin supported pd 23 ag membranes evidence of ultrahigh Hydrogen Flux after air treatment
Journal of Membrane Science, 2011Co-Authors: Thijs Peters, M Stange, Rune BredesenAbstract:Abstract The Hydrogen Flux, selectivity and stability of ∼1.9–3.8 μm thick supported palladium alloy (Pd–23%Ag) films are reported. Applying a Hydrogen feed pressure of 26 bar, one of the highest Hydrogen Fluxes reported equal to 2477 mL min−1 cm−2 (STP) or 132 kg H2 m−2 h−1 was measured at 400 °C. This Flux corresponds to a permeance of 1.5 × 10−2 mol m−2 s−1 Pa−0.5. The H2/N2 permselectivity at 25 bar transmembrane pressure difference was 2900. Allowing the value of n to float between 0.5 and 1, in order to obtain the best fit between the Fluxes and ( p H 2 r e t n − p H 2 p e r m n ) , gives a value for n equal to 0.631 after air pre-treatment and correction for the support resistance. The analysis of Flux data suggests that diffusional transport through the membrane is rate-limiting. By forcing n equal to 0.5, permeability values as a function of the pressure have been obtained linking it qualitatively to solution and diffusion behaviour. At the limiting value of zero Hydrogen partial pressure, Hydrogen permeabilities of 9.1 × 10−9 mol m−1 s−1 Pa−0.5 and 3.2 × 10−8 mol m−1 s−1 Pa−0.5 have been obtained before and after air treatment, respectively. During continuous operation over 85 days, the membrane showed a good stability up to 350 °C while the nitrogen leakage Flux increases very slowly at higher temperatures (Pfeed = 10 bar).
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On the high pressure performance of thin supported Pd–23%Ag membranes—Evidence of ultrahigh Hydrogen Flux after air treatment
Journal of Membrane Science, 2010Co-Authors: Thijs Peters, M Stange, Rune BredesenAbstract:Abstract The Hydrogen Flux, selectivity and stability of ∼1.9–3.8 μm thick supported palladium alloy (Pd–23%Ag) films are reported. Applying a Hydrogen feed pressure of 26 bar, one of the highest Hydrogen Fluxes reported equal to 2477 mL min−1 cm−2 (STP) or 132 kg H2 m−2 h−1 was measured at 400 °C. This Flux corresponds to a permeance of 1.5 × 10−2 mol m−2 s−1 Pa−0.5. The H2/N2 permselectivity at 25 bar transmembrane pressure difference was 2900. Allowing the value of n to float between 0.5 and 1, in order to obtain the best fit between the Fluxes and ( p H 2 r e t n − p H 2 p e r m n ) , gives a value for n equal to 0.631 after air pre-treatment and correction for the support resistance. The analysis of Flux data suggests that diffusional transport through the membrane is rate-limiting. By forcing n equal to 0.5, permeability values as a function of the pressure have been obtained linking it qualitatively to solution and diffusion behaviour. At the limiting value of zero Hydrogen partial pressure, Hydrogen permeabilities of 9.1 × 10−9 mol m−1 s−1 Pa−0.5 and 3.2 × 10−8 mol m−1 s−1 Pa−0.5 have been obtained before and after air treatment, respectively. During continuous operation over 85 days, the membrane showed a good stability up to 350 °C while the nitrogen leakage Flux increases very slowly at higher temperatures (Pfeed = 10 bar).
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high pressure performance of thin pd 23 ag stainless steel composite membranes in water gas shift gas mixtures influence of dilution mass transfer and surface effects on the Hydrogen Flux
Journal of Membrane Science, 2008Co-Authors: T A Peters, M Stange, Hallgeir Klette, Rune BredesenAbstract:Abstract The Hydrogen permeation and stability of tubular palladium alloy (Pd–23%Ag) composite membranes have been investigated at elevated temperatures and pressures. In our analysis we differentiate between dilution of Hydrogen by other gas components, Hydrogen depletion along the membrane length, concentration polarization adjacent to the membrane surface, and effects due to surface adsorption, on the Hydrogen Flux. A maximum H 2 Flux of 1223 mL cm −2 min −1 or 8.4 mol m −2 s −1 was obtained at 400 °C and 26 bar Hydrogen feed pressure, corresponding to a permeance of 6.4 × 10 −3 mol m −2 s −1 Pa −0.5 . A good linear relationship was found between Hydrogen Flux and pressure as predicted for rate controlling bulk diffusion. In a mixture of 50% H 2 + 50% N 2 a maximum H 2 Flux of 230 mL cm −2 min −1 and separation factor of 1400 were achieved at 26 bar. The large reduction in Hydrogen Flux is mainly caused by the build-up of a Hydrogen-depleted concentration polarization layer adjacent to the membrane due to insufficient mass transport in the gas phase. Substituting N 2 with CO 2 results in further reduction of Flux, but not as large as for CO where adsorption prevail as the dominating flow controlling factor. In WGS conditions (57.5% H 2 , 18.7% CO 2 , 3.8% CO, 1.2% CH 4 and 18.7% steam), a H 2 permeance of 1.1 × 10 −3 mol m −2 s −1 Pa −0.5 was found at 400 °C and 26 bar feed pressure. Operating the membrane for 500 h under various conditions (WGS and H 2 + N 2 mixtures) at 26 bars indicated no membrane failure, but a small decrease in Flux. A peculiar Flux inhibiting effect of long term exposure to high concentration of N 2 was observed. The membrane surface was deformed and expanded after operation, mainly following the topography of the macroporous support.
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High pressure performance of thin Pd–23%Ag/stainless steel composite membranes in water gas shift gas mixtures; influence of dilution, mass transfer and surface effects on the Hydrogen Flux
Journal of Membrane Science, 2007Co-Authors: Thijs Peters, M Stange, Hallgeir Klette, Rune BredesenAbstract:Abstract The Hydrogen permeation and stability of tubular palladium alloy (Pd–23%Ag) composite membranes have been investigated at elevated temperatures and pressures. In our analysis we differentiate between dilution of Hydrogen by other gas components, Hydrogen depletion along the membrane length, concentration polarization adjacent to the membrane surface, and effects due to surface adsorption, on the Hydrogen Flux. A maximum H 2 Flux of 1223 mL cm −2 min −1 or 8.4 mol m −2 s −1 was obtained at 400 °C and 26 bar Hydrogen feed pressure, corresponding to a permeance of 6.4 × 10 −3 mol m −2 s −1 Pa −0.5 . A good linear relationship was found between Hydrogen Flux and pressure as predicted for rate controlling bulk diffusion. In a mixture of 50% H 2 + 50% N 2 a maximum H 2 Flux of 230 mL cm −2 min −1 and separation factor of 1400 were achieved at 26 bar. The large reduction in Hydrogen Flux is mainly caused by the build-up of a Hydrogen-depleted concentration polarization layer adjacent to the membrane due to insufficient mass transport in the gas phase. Substituting N 2 with CO 2 results in further reduction of Flux, but not as large as for CO where adsorption prevail as the dominating flow controlling factor. In WGS conditions (57.5% H 2 , 18.7% CO 2 , 3.8% CO, 1.2% CH 4 and 18.7% steam), a H 2 permeance of 1.1 × 10 −3 mol m −2 s −1 Pa −0.5 was found at 400 °C and 26 bar feed pressure. Operating the membrane for 500 h under various conditions (WGS and H 2 + N 2 mixtures) at 26 bars indicated no membrane failure, but a small decrease in Flux. A peculiar Flux inhibiting effect of long term exposure to high concentration of N 2 was observed. The membrane surface was deformed and expanded after operation, mainly following the topography of the macroporous support.
Thijs Peters - One of the best experts on this subject based on the ideXlab platform.
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New Insight to the Effects of Heat Treatment in Air on the Permeation Properties of Thin Pd77%Ag23% Membranes
Membranes, 2018Co-Authors: Nicla Vicinanza, Rune Bredesen, Thijs Peters, Ingeborg-helene Svenum, Hilde J. VenvikAbstract:Sputtered Pd77%Ag23% membranes of thickness 2.2–8.5 µm were subjected to a three-step heat treatment in air (HTA) to investigate the relation between thickness and the reported beneficial effects of HTA on Hydrogen transport. The permeability experiments were complimented by volumetric Hydrogen sorption measurements and atomic force microscopy (AFM) imaging in order to relate the observed effects to changes in Hydrogen solubility and/or structure. The results show that the HTA—essentially an oxidation-reduction cycle—mainly affects the thinner membranes, with the Hydrogen Flux increasing stepwise upon HTA of each membrane side. The Hydrogen solubility is found to remain constant upon HTA, and the change must therefore be attributed to improved transport kinetics. The HTA procedure appears to shift the transition from the surface to bulk-limited transport to lower thickness, roughly from ~5 to ≤2.2 µm under the conditions applied here. Although the surface topography results indicate that HTA influences the surface roughness and increases the effective membrane surface area, this cannot be the sole explanation for the observed Hydrogen Flux increase. This is because considerable surface roughening occurs during Hydrogen permeation (no HTA) as well, but not accompanied by the same Hydrogen Flux enhancement. The latter effect is particularly pronounced for thinner membranes, implying that the structural changes may be dependent on the magnitude of the Hydrogen Flux.
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on the high pressure performance of thin supported pd 23 ag membranes evidence of ultrahigh Hydrogen Flux after air treatment
Journal of Membrane Science, 2011Co-Authors: Thijs Peters, M Stange, Rune BredesenAbstract:Abstract The Hydrogen Flux, selectivity and stability of ∼1.9–3.8 μm thick supported palladium alloy (Pd–23%Ag) films are reported. Applying a Hydrogen feed pressure of 26 bar, one of the highest Hydrogen Fluxes reported equal to 2477 mL min−1 cm−2 (STP) or 132 kg H2 m−2 h−1 was measured at 400 °C. This Flux corresponds to a permeance of 1.5 × 10−2 mol m−2 s−1 Pa−0.5. The H2/N2 permselectivity at 25 bar transmembrane pressure difference was 2900. Allowing the value of n to float between 0.5 and 1, in order to obtain the best fit between the Fluxes and ( p H 2 r e t n − p H 2 p e r m n ) , gives a value for n equal to 0.631 after air pre-treatment and correction for the support resistance. The analysis of Flux data suggests that diffusional transport through the membrane is rate-limiting. By forcing n equal to 0.5, permeability values as a function of the pressure have been obtained linking it qualitatively to solution and diffusion behaviour. At the limiting value of zero Hydrogen partial pressure, Hydrogen permeabilities of 9.1 × 10−9 mol m−1 s−1 Pa−0.5 and 3.2 × 10−8 mol m−1 s−1 Pa−0.5 have been obtained before and after air treatment, respectively. During continuous operation over 85 days, the membrane showed a good stability up to 350 °C while the nitrogen leakage Flux increases very slowly at higher temperatures (Pfeed = 10 bar).
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On the high pressure performance of thin supported Pd–23%Ag membranes—Evidence of ultrahigh Hydrogen Flux after air treatment
Journal of Membrane Science, 2010Co-Authors: Thijs Peters, M Stange, Rune BredesenAbstract:Abstract The Hydrogen Flux, selectivity and stability of ∼1.9–3.8 μm thick supported palladium alloy (Pd–23%Ag) films are reported. Applying a Hydrogen feed pressure of 26 bar, one of the highest Hydrogen Fluxes reported equal to 2477 mL min−1 cm−2 (STP) or 132 kg H2 m−2 h−1 was measured at 400 °C. This Flux corresponds to a permeance of 1.5 × 10−2 mol m−2 s−1 Pa−0.5. The H2/N2 permselectivity at 25 bar transmembrane pressure difference was 2900. Allowing the value of n to float between 0.5 and 1, in order to obtain the best fit between the Fluxes and ( p H 2 r e t n − p H 2 p e r m n ) , gives a value for n equal to 0.631 after air pre-treatment and correction for the support resistance. The analysis of Flux data suggests that diffusional transport through the membrane is rate-limiting. By forcing n equal to 0.5, permeability values as a function of the pressure have been obtained linking it qualitatively to solution and diffusion behaviour. At the limiting value of zero Hydrogen partial pressure, Hydrogen permeabilities of 9.1 × 10−9 mol m−1 s−1 Pa−0.5 and 3.2 × 10−8 mol m−1 s−1 Pa−0.5 have been obtained before and after air treatment, respectively. During continuous operation over 85 days, the membrane showed a good stability up to 350 °C while the nitrogen leakage Flux increases very slowly at higher temperatures (Pfeed = 10 bar).
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High pressure performance of thin Pd–23%Ag/stainless steel composite membranes in water gas shift gas mixtures; influence of dilution, mass transfer and surface effects on the Hydrogen Flux
Journal of Membrane Science, 2007Co-Authors: Thijs Peters, M Stange, Hallgeir Klette, Rune BredesenAbstract:Abstract The Hydrogen permeation and stability of tubular palladium alloy (Pd–23%Ag) composite membranes have been investigated at elevated temperatures and pressures. In our analysis we differentiate between dilution of Hydrogen by other gas components, Hydrogen depletion along the membrane length, concentration polarization adjacent to the membrane surface, and effects due to surface adsorption, on the Hydrogen Flux. A maximum H 2 Flux of 1223 mL cm −2 min −1 or 8.4 mol m −2 s −1 was obtained at 400 °C and 26 bar Hydrogen feed pressure, corresponding to a permeance of 6.4 × 10 −3 mol m −2 s −1 Pa −0.5 . A good linear relationship was found between Hydrogen Flux and pressure as predicted for rate controlling bulk diffusion. In a mixture of 50% H 2 + 50% N 2 a maximum H 2 Flux of 230 mL cm −2 min −1 and separation factor of 1400 were achieved at 26 bar. The large reduction in Hydrogen Flux is mainly caused by the build-up of a Hydrogen-depleted concentration polarization layer adjacent to the membrane due to insufficient mass transport in the gas phase. Substituting N 2 with CO 2 results in further reduction of Flux, but not as large as for CO where adsorption prevail as the dominating flow controlling factor. In WGS conditions (57.5% H 2 , 18.7% CO 2 , 3.8% CO, 1.2% CH 4 and 18.7% steam), a H 2 permeance of 1.1 × 10 −3 mol m −2 s −1 Pa −0.5 was found at 400 °C and 26 bar feed pressure. Operating the membrane for 500 h under various conditions (WGS and H 2 + N 2 mixtures) at 26 bars indicated no membrane failure, but a small decrease in Flux. A peculiar Flux inhibiting effect of long term exposure to high concentration of N 2 was observed. The membrane surface was deformed and expanded after operation, mainly following the topography of the macroporous support.
M Stange - One of the best experts on this subject based on the ideXlab platform.
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on the high pressure performance of thin supported pd 23 ag membranes evidence of ultrahigh Hydrogen Flux after air treatment
Journal of Membrane Science, 2011Co-Authors: Thijs Peters, M Stange, Rune BredesenAbstract:Abstract The Hydrogen Flux, selectivity and stability of ∼1.9–3.8 μm thick supported palladium alloy (Pd–23%Ag) films are reported. Applying a Hydrogen feed pressure of 26 bar, one of the highest Hydrogen Fluxes reported equal to 2477 mL min−1 cm−2 (STP) or 132 kg H2 m−2 h−1 was measured at 400 °C. This Flux corresponds to a permeance of 1.5 × 10−2 mol m−2 s−1 Pa−0.5. The H2/N2 permselectivity at 25 bar transmembrane pressure difference was 2900. Allowing the value of n to float between 0.5 and 1, in order to obtain the best fit between the Fluxes and ( p H 2 r e t n − p H 2 p e r m n ) , gives a value for n equal to 0.631 after air pre-treatment and correction for the support resistance. The analysis of Flux data suggests that diffusional transport through the membrane is rate-limiting. By forcing n equal to 0.5, permeability values as a function of the pressure have been obtained linking it qualitatively to solution and diffusion behaviour. At the limiting value of zero Hydrogen partial pressure, Hydrogen permeabilities of 9.1 × 10−9 mol m−1 s−1 Pa−0.5 and 3.2 × 10−8 mol m−1 s−1 Pa−0.5 have been obtained before and after air treatment, respectively. During continuous operation over 85 days, the membrane showed a good stability up to 350 °C while the nitrogen leakage Flux increases very slowly at higher temperatures (Pfeed = 10 bar).
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On the high pressure performance of thin supported Pd–23%Ag membranes—Evidence of ultrahigh Hydrogen Flux after air treatment
Journal of Membrane Science, 2010Co-Authors: Thijs Peters, M Stange, Rune BredesenAbstract:Abstract The Hydrogen Flux, selectivity and stability of ∼1.9–3.8 μm thick supported palladium alloy (Pd–23%Ag) films are reported. Applying a Hydrogen feed pressure of 26 bar, one of the highest Hydrogen Fluxes reported equal to 2477 mL min−1 cm−2 (STP) or 132 kg H2 m−2 h−1 was measured at 400 °C. This Flux corresponds to a permeance of 1.5 × 10−2 mol m−2 s−1 Pa−0.5. The H2/N2 permselectivity at 25 bar transmembrane pressure difference was 2900. Allowing the value of n to float between 0.5 and 1, in order to obtain the best fit between the Fluxes and ( p H 2 r e t n − p H 2 p e r m n ) , gives a value for n equal to 0.631 after air pre-treatment and correction for the support resistance. The analysis of Flux data suggests that diffusional transport through the membrane is rate-limiting. By forcing n equal to 0.5, permeability values as a function of the pressure have been obtained linking it qualitatively to solution and diffusion behaviour. At the limiting value of zero Hydrogen partial pressure, Hydrogen permeabilities of 9.1 × 10−9 mol m−1 s−1 Pa−0.5 and 3.2 × 10−8 mol m−1 s−1 Pa−0.5 have been obtained before and after air treatment, respectively. During continuous operation over 85 days, the membrane showed a good stability up to 350 °C while the nitrogen leakage Flux increases very slowly at higher temperatures (Pfeed = 10 bar).
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high pressure performance of thin pd 23 ag stainless steel composite membranes in water gas shift gas mixtures influence of dilution mass transfer and surface effects on the Hydrogen Flux
Journal of Membrane Science, 2008Co-Authors: T A Peters, M Stange, Hallgeir Klette, Rune BredesenAbstract:Abstract The Hydrogen permeation and stability of tubular palladium alloy (Pd–23%Ag) composite membranes have been investigated at elevated temperatures and pressures. In our analysis we differentiate between dilution of Hydrogen by other gas components, Hydrogen depletion along the membrane length, concentration polarization adjacent to the membrane surface, and effects due to surface adsorption, on the Hydrogen Flux. A maximum H 2 Flux of 1223 mL cm −2 min −1 or 8.4 mol m −2 s −1 was obtained at 400 °C and 26 bar Hydrogen feed pressure, corresponding to a permeance of 6.4 × 10 −3 mol m −2 s −1 Pa −0.5 . A good linear relationship was found between Hydrogen Flux and pressure as predicted for rate controlling bulk diffusion. In a mixture of 50% H 2 + 50% N 2 a maximum H 2 Flux of 230 mL cm −2 min −1 and separation factor of 1400 were achieved at 26 bar. The large reduction in Hydrogen Flux is mainly caused by the build-up of a Hydrogen-depleted concentration polarization layer adjacent to the membrane due to insufficient mass transport in the gas phase. Substituting N 2 with CO 2 results in further reduction of Flux, but not as large as for CO where adsorption prevail as the dominating flow controlling factor. In WGS conditions (57.5% H 2 , 18.7% CO 2 , 3.8% CO, 1.2% CH 4 and 18.7% steam), a H 2 permeance of 1.1 × 10 −3 mol m −2 s −1 Pa −0.5 was found at 400 °C and 26 bar feed pressure. Operating the membrane for 500 h under various conditions (WGS and H 2 + N 2 mixtures) at 26 bars indicated no membrane failure, but a small decrease in Flux. A peculiar Flux inhibiting effect of long term exposure to high concentration of N 2 was observed. The membrane surface was deformed and expanded after operation, mainly following the topography of the macroporous support.
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High pressure performance of thin Pd–23%Ag/stainless steel composite membranes in water gas shift gas mixtures; influence of dilution, mass transfer and surface effects on the Hydrogen Flux
Journal of Membrane Science, 2007Co-Authors: Thijs Peters, M Stange, Hallgeir Klette, Rune BredesenAbstract:Abstract The Hydrogen permeation and stability of tubular palladium alloy (Pd–23%Ag) composite membranes have been investigated at elevated temperatures and pressures. In our analysis we differentiate between dilution of Hydrogen by other gas components, Hydrogen depletion along the membrane length, concentration polarization adjacent to the membrane surface, and effects due to surface adsorption, on the Hydrogen Flux. A maximum H 2 Flux of 1223 mL cm −2 min −1 or 8.4 mol m −2 s −1 was obtained at 400 °C and 26 bar Hydrogen feed pressure, corresponding to a permeance of 6.4 × 10 −3 mol m −2 s −1 Pa −0.5 . A good linear relationship was found between Hydrogen Flux and pressure as predicted for rate controlling bulk diffusion. In a mixture of 50% H 2 + 50% N 2 a maximum H 2 Flux of 230 mL cm −2 min −1 and separation factor of 1400 were achieved at 26 bar. The large reduction in Hydrogen Flux is mainly caused by the build-up of a Hydrogen-depleted concentration polarization layer adjacent to the membrane due to insufficient mass transport in the gas phase. Substituting N 2 with CO 2 results in further reduction of Flux, but not as large as for CO where adsorption prevail as the dominating flow controlling factor. In WGS conditions (57.5% H 2 , 18.7% CO 2 , 3.8% CO, 1.2% CH 4 and 18.7% steam), a H 2 permeance of 1.1 × 10 −3 mol m −2 s −1 Pa −0.5 was found at 400 °C and 26 bar feed pressure. Operating the membrane for 500 h under various conditions (WGS and H 2 + N 2 mixtures) at 26 bars indicated no membrane failure, but a small decrease in Flux. A peculiar Flux inhibiting effect of long term exposure to high concentration of N 2 was observed. The membrane surface was deformed and expanded after operation, mainly following the topography of the macroporous support.
Kaneaki Tsuzaki - One of the best experts on this subject based on the ideXlab platform.
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Surface orientation dependence of Hydrogen Flux in lenticular martensite of an Fe-Ni-C alloy clarified through in situ silver decoration technique
Materials Letters, 2018Co-Authors: Motomichi Koyama, Daisuke Yamasaki, Kaneaki TsuzakiAbstract:Abstract An in situ silver decoration technique was applied to investigate the effect of microstructure on Hydrogen Flux in an austenite/α′-martensite dual-phase Fe-32Ni-0.2C alloy. Using time-resolved Hydrogen mapping, the surface orientation of the body-centered cubic lenticular martensite was found to have a significant effect on Hydrogen Flux. The Hydrogen Flux was particularly high at the near-〈0 0 1〉, while it was the lowest at the near-〈1 1 1〉 surface. This dependence of Hydrogen Flux on the surface orientation is attributed to Hydrogen trapping at dislocations in the martensite. Particularly, 〈1 1 1〉 twinning-shear in the martensite enhances Hydrogen trapping at dislocations, suppressing Hydrogen diffusion in the shortest path of grains orientated to 〈1 1 1〉.
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Reply to comments on the paper “In situ observations of silver-decoration evolution under Hydrogen permeation: Effects of grain boundary misorientation on Hydrogen Flux in pure iron” by Gavriljuk and Teus
Scripta Materialia, 2017Co-Authors: Motomichi Koyama, Daisuke Yamasaki, Kaneaki TsuzakiAbstract:Abstract As a response to a comment by Gavriljuk and Teus, we discuss the effects of Hydrogen-charging-induced crack formation and plastic deformation on a high Hydrogen Flux along the grain boundaries in pure iron. Because no cracks were observed in the microstructure of the pure iron specimen used in our study, the effects of crack formation could be ruled out. In contrast, dislocation localization near grain boundaries was observed, possibly due to a Hydrogen concentration gradient; therefore, the presence of dislocations may assist Hydrogen segregation and cause the high Hydrogen Flux.
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In situ observations of silver-decoration evolution under Hydrogen permeation: Effects of grain boundary misorientation on Hydrogen Flux in pure iron
Scripta Materialia, 2017Co-Authors: Motomichi Koyama, Daisuke Yamasaki, Tatsuya Nagashima, Cemal Cem Tasan, Kaneaki TsuzakiAbstract:Abstract An in situ silver decoration technique using a light microscope was developed. Hydrogen was introduced from the bottom surface of an annealed pure iron specimen, and its top surface was covered with a chemical solution containing silver ions. Samples were exposed for sufficient time for Hydrogen permeation to occur from the back to the top surface. The resultant in situ silver decoration visualized that the Hydrogen Flux through low-angle grain boundaries is lower than that observed at high-angle grain boundaries. The in situ silver decoration technique can be used for kinetic analysis of solute Hydrogen in ferritic iron and steels.
Fausto Gallucci - One of the best experts on this subject based on the ideXlab platform.
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Degradation of Pd/Nb30Ti35Co35/Pd Hydrogen permeable membrane: A numerical description
Journal of Membrane Science, 2020Co-Authors: Xiao Liang, Fausto Gallucci, Hiromi Nagaumi, Jingjie Guo, Martin Van Sint Annaland, Dongmei LiuAbstract:Abstract The Hydrogen Flux degradation in Hydrogen permeation tests of Pd/Nb30Ti35Co35 (at.%)/Pd composite membranes was experimentally investigated at temperatures from 400 to 650 °C. The Hydrogen Fluxes through the Pd/Nb30Ti35Co35/Pd membranes during isothermal long-term Hydrogen permeation tests above 500 °C exhibit two Hydrogen-Flux-decline steps. The aggregation of the Pd-catalytic layer and the boundary layer formed between Pd and Nb30Ti35Co35 due to interdiffusion were experimentally confirmed contributing to the degradation of the Hydrogen Flux through the Pd/Nb30Ti35Co35/Pd membrane. Modelling work was carried out to reveal and validate the temperature-dependence of the two attributing factors to the degradation of Hydrogen permeation Flux.
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Influence of H2S on the Hydrogen Flux of thin-film PdAgAu membranes
International Journal of Hydrogen Energy, 2020Co-Authors: Niek De Nooijer, Martin Van Sint Annaland, David A. Pacheco Tanaka, Julio Davalos Sanchez, J. Melendez, Ekain Fernandez, Fausto GallucciAbstract:Abstract Pd-based membranes have the potential to be used for Hydrogen purification and production in membrane reactors. However, the presence of impurities in the feedstock, such as H2S can poison the membrane, thus decreasing the Hydrogen permeation by blocking and deactivating active sites of the Pd-alloy on the membrane surface. H2S at high concentrations can even destroy the membrane by the formation of Pd4S. It is known that alloying of Pd with Au enhances the membrane resistance to H2S. This work reports the performance of six PdAgAu/Al2O3 supported membranes, prepared by electroless plating combined with PVD under exposure to trace amounts (
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Ti–Ni–Pd dense membranes—The effect of the gas mixtures on the Hydrogen permeation
Journal of Membrane Science, 2007Co-Authors: Angelo Basile, Fausto Gallucci, Adolfo Iulianelli, Gf Tereschenko, M. M. Ermilova, N. V. OrekhovaAbstract:Abstract In this experimental work the influence of co-existing gases on the Hydrogen permeation through a Ti–Ni–Pd membrane was studied. It was found that nitrogen, carbon dioxide and helium do not influence the Hydrogen permeation through the dense membrane. However, carbon monoxide influences the Hydrogen Flux at each temperature investigated (400–500 °C). The results show that for low CO concentration (i.e. at H 2 upstream >80%), the Hydrogen Flux through the membrane decreases faster than linearly, while, at H 2 upstream
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The effect of the Hydrogen Flux pressure and temperature dependence factors on the membrane reactor performances
International Journal of Hydrogen Energy, 2007Co-Authors: Fausto Gallucci, De M Falco, Silvano Tosti, Luigi Marrelli, Angelo BasileAbstract:Abstract In this theoretical work the effects of the parameters governing the Hydrogen permeation through the dense palladium membranes on the membrane reactor performances are studied. The model for the methane steam reforming was used as test reaction system and the effects of the parameters of the Richardson equation ( n , P 0 and E a ), on the reactor performances were studied. The effect of the Hydrogen Flux pressure and temperature dependence factors on the methane conversion and on the Hydrogen recovery for both the co-current and counter-current modes are reported and discussed.
