The Experts below are selected from a list of 168 Experts worldwide ranked by ideXlab platform
Sun-ju Song - One of the best experts on this subject based on the ideXlab platform.
-
Hydrogen Separation by dual functional cermet Membranes with self-repairing capability against the damage by H2S
Journal of Membrane Science, 2013Co-Authors: Sang-yun Jeon, M.-b. Choi, Bhupendra Singh, Sun-ju SongAbstract:Abstract A Pd-YSZ cermet is synthesized to fabricate a Hydrogen Separation Membrane that performs coupled operations of the Separation of Hydrogen from a mixed-gas stream containing H 2 S and the simultaneous production of Hydrogen by water-splitting. The reason for the loss of Hydrogen permeation function of Pd-based Membranes in H 2 S environment has been the formation of Pd 4 S by the reaction of H 2 S with Pd. In the present study, the high thermal and chemical stability of YSZ in H 2 S environment helps operation at higher temperature to attain a high Hydrogen permeation flux and, also, the Pd-YSZ Membrane shows better tolerance against H 2 S because of its self-repairing capacity against the damage by H 2 S. The self-repairing capacity of Pd-YSZ Membrane originates mainly from the conversion of Pd 4 S back into metallic Pd and SO 2 by ambipolar-diffused oxygen obtained from water-splitting. Also, the operation at higher temperatures helps in reducing the effective concentration of H 2 S in the mixed-gas stream by converting a part of H 2 S into SO 2 and H 2 by ambipolar-diffused oxygen assisted reactions. The Pd-YSZ cermet Membrane devised in the present work gives a comprehensive solution to many issues related with the Hydrogen Separation Membranes.
-
High sulfur tolerance dual-functional cermet Hydrogen Separation Membranes
Journal of Membrane Science, 2011Co-Authors: Sang-yun Jeon, Eric D. Wachsman, M.-b. Choi, C.-n. Park, Sun-ju SongAbstract:Abstract There has been an urgent need for new Hydrogen Separation Membrane materials at an acceptable cost that can operate under demanding environmental conditions while providing the desired performance. The proposed method promises to substantially decrease the material cost while maximizing the Hydrogen permeation rates while meeting strong resistance to Hydrogen embrittlement, not to mention that the enhancement of mechanical strength by using cermet. Most importantly, they clearly further enhance the sulfur tolerance by using not only more H 2 S tolerant alloys but also higher oxygen ion conducting ceramics as matrix. Our results shows that no sharp drop in Hydrogen permeation flux was observed at 220 ppm H 2 S, which greatly exceeds the theoretical values, a 40 ppm H 2 S with10% H 2 /balance He at 600 °C, confirming that the permeated oxygen from the water splitting should have oxidized the sulfur to prevent any palladium sulfide (Pd 4 S) formation on the Pd-cermet Membrane surface.
-
defect structure and transport properties of ni srceo3 δ cermet for Hydrogen Separation Membrane
Journal of The Electrochemical Society, 2005Co-Authors: Sun-ju Song, Eric D. Wachsman, L. Chen, S. E. Dorris, T H Lee, U. BalachandranAbstract:Research on Hydrogen Separation Membranes is motivated by the increasing demand for an environmentally benign, inexpensive technology for separating Hydrogen from gas mixtures. Although most studies of Hydrogen Separation Membranes have focused on proton-conducting oxides by themselves, the addition of metal to these oxides increases their Hydrogen permeability and improves their mechanical stability. This study began by determining Hydrogen permeation properties of SrCe0.8Yb0.2O3-delta (SCYb). The results showed that at the investigated temperatures (600-900 degrees C), the Hydrogen permeation rate is limited by electron flow. To further enhance Hydrogen permeability, a cermet (i.e., ceramic-metal composite) Membrane was made by adding Ni to the SCYb. At 900 degrees C, with 20% H-2/balance He as a feed gas (p(H2O) = 0.03 atm), the Hydrogen permeation rate was 0.105 cm(3)/min cm(2) for 0.25-mm-thick Ni/SCYb and 0.008 cm(3)/min cm(2) for SCYb (0.7-mm thick). The dependence of Hydrogen permeability on temperature and Hydrogen partial-pressure gradients was also determined. The proton conductivity (approximate to ambipolar conductivity) was extracted from the dependence of Hydrogen permeability on Hydrogen potential gradients. The results demonstrate that adding Ni to SCYb considerably increases its Hydrogen permeability by increasing its electron conductivity.
-
Defect structure and transport properties of Ni-SrCeO3-δcermet for Hydrogen Separation Membrane
Journal of The Electrochemical Society, 2005Co-Authors: Sun-ju Song, Tae H. Lee, Eric D. Wachsman, L. Chen, S. E. Dorris, U. BalachandranAbstract:Research on Hydrogen Separation Membranes is motivated by the increasing demand for an environmentally benign, inexpensive technology for separating Hydrogen from gas mixtures. Although most studies of Hydrogen SeparationMembranes have focused on proton-conducting oxides by themselves, the addition of metal to these oxides increases their Hydrogen permeability and improves their mechanical stability. This study began by determining Hydrogen permeation properties of Srce 0 . 8 Yb 0 . 2 O 3 - δ (SCYb). The results showed that at the investigated temperatures (600-900°C), the Hydrogen permeation rate is limited by electron flow. To further enhance Hydrogen permeability, a cermet (i.e., ceramic-metal composite) Membrane was made by adding Ni to the SCYb. At 900°C, with 20% H 2 /balance He as a feed gas (pH 2 o = 0.03 atm), the Hydrogen permeation rate was 0.105 cm 3 /min cm 2 for 0.25-mm-thick Ni/SCYb and 0.008 cm 3 /min cm 2 for SCYb (0.7-mm thick). The dependence of Hydrogen permeability on temperature and Hydrogen partial-pressure gradients was also determined. The proton conductivity (ambipolar conductivity) was extracted from the dependence of Hydrogen permeability on Hydrogen potential gradients. The results demonstrate that adding Ni to SCYb considerably increases its Hydrogen permeability by increasing its electron conductivity.
-
Defect Structure and Transport Properties of Ni – SrCeO3 − δ Cermet for Hydrogen Separation Membrane
Journal of The Electrochemical Society, 2005Co-Authors: Sun-ju Song, Tae H. Lee, Eric D. Wachsman, L. Chen, S. E. Dorris, U. BalachandranAbstract:Research on Hydrogen Separation Membranes is motivated by the increasing demand for an environmentally benign, inexpensive technology for separating Hydrogen from gas mixtures. Although most studies of Hydrogen Separation Membranes have focused on proton-conducting oxides by themselves, the addition of metal to these oxides increases their Hydrogen permeability and improves their mechanical stability. This study began by determining Hydrogen permeation properties of SrCe0.8Yb0.2O3-delta (SCYb). The results showed that at the investigated temperatures (600-900 degrees C), the Hydrogen permeation rate is limited by electron flow. To further enhance Hydrogen permeability, a cermet (i.e., ceramic-metal composite) Membrane was made by adding Ni to the SCYb. At 900 degrees C, with 20% H-2/balance He as a feed gas (p(H2O) = 0.03 atm), the Hydrogen permeation rate was 0.105 cm(3)/min cm(2) for 0.25-mm-thick Ni/SCYb and 0.008 cm(3)/min cm(2) for SCYb (0.7-mm thick). The dependence of Hydrogen permeability on temperature and Hydrogen partial-pressure gradients was also determined. The proton conductivity (approximate to ambipolar conductivity) was extracted from the dependence of Hydrogen permeability on Hydrogen potential gradients. The results demonstrate that adding Ni to SCYb considerably increases its Hydrogen permeability by increasing its electron conductivity.
Robert H. Williams - One of the best experts on this subject based on the ideXlab platform.
-
Carbon-Free Hydrogen and Electricity From Coal: Options for Syngas Cooling in Systems Using a Hydrogen Separation Membrane Reactor
Journal of Engineering for Gas Turbines and Power, 2008Co-Authors: Luca De Lorenzo, Thomas G. Kreutz, Paolo Chiesa, Robert H. WilliamsAbstract:Conversion of coal to carbon-free energy carriers, H-2 and electricity, with CO{sub 2} capture and storage may have the potential to satisfy at a comparatively low cost much of the energy requirements in a carbon-constrained world. This study focuses on the synergy between H{sub 2} Separation Membrane reactors (HSMRs) and syngas cooling with radiant and convective heat exchanges; such 'syngas coolers' invariably boost system efficiency over that obtained with quench-cooled gasification. Conventional H{sub 2} Separation requires a relatively high steam-to-carbon ratio (SIC) to achieve a high level of H{sub 2} production, and thus is well matched to relatively inefficient quench cooling. In contrast, HSMRs shift the WGS equilibrium by continuously extracting reaction product H{sub 2}, thereby allowing a much lower SIC ratio and consequently a higher degree of heat recovery and (potentially) system efficiency. We first present a parametric analysis illuminating the interaction between the syngas coolers, high temperature WGS reactor and HSMR. We then compare the performance and cost of six different plant configurations, highlighting (1) the relative merits of the two syngas cooling methods in Membrane-based systems, and (2) the comparative performance of conventional versus HSMR-based H{sub 2} Separation in, plants with syngas coolers.
-
Carbon-Free Hydrogen and Electricity From Coal: Options for Syngas Cooling in Systems Using a Hydrogen Separation Membrane Reactor
Volume 1: Turbo Expo 2005, 2005Co-Authors: Luca De Lorenzo, Thomas G. Kreutz, Paolo Chiesa, Robert H. WilliamsAbstract:Conversion of coal to carbon-free energy carriers, H2 and electricity, with CO2 capture and storage may have the potential to satisfy at a comparatively low cost much of the energy requirements in a carbon-constrained world. In a set of recent studies, we have assessed the thermodynamic and economic performance of numerous coal-to-H2 plants that employ O2 -blown, entrained-flow gasification and sour water-gas shift (WGS) reactors, examining the effects of system pressure, syngas cooling via quench versus heat exchangers, “conventional” H2 Separation via pressure swing adsorption (PSA) versus novel Membrane-based approaches, and various gas turbine technologies for generating co-product electricity. This study focuses on the synergy between H2 Separation Membrane reactors (HSMR) and syngas cooling with radiant and convective heat exchangers; such “syngas coolers” invariably boost system efficiency over that obtained with quench-cooled gasification. “Conventional” H2 Separation requires a relatively high steam-to-carbon ratio (S/C) to achieve a high level of H2 production, and thus is well matched to relatively inefficient quench cooling. In contrast, HSMRs shift the WGS equilibrium by continuously extracting reaction product H2 , thereby allowing a much lower S/C ratio and consequently a higher degree of heat recovery and (potentially) system efficiency. We first present a parametric analysis illuminating the interaction between the syngas coolers, high temperature WGS reactor, and HSMR. We then compare the performance and cost of six different plant configurations, highlighting: 1) the relative merits of the two syngas cooling methods in Membrane-based systems, and 2) the comparative performance of “conventional” versus HSMR-based H2 Separation in plants with syngas coolers.Copyright © 2005 by ASME
Hazzim F Abbas - One of the best experts on this subject based on the ideXlab platform.
-
production of greenhouse gas free Hydrogen by thermocatalytic decomposition of methane a review
Renewable & Sustainable Energy Reviews, 2015Co-Authors: U.p.m. Ashik, Wan Mohd Ashri Wan Daud, Hazzim F AbbasAbstract:Thermocatalytic decomposition of methane (TCD) is a fully green single step technology for producing Hydrogen and nano-carbon. This review studying all development in laboratory-scale research on TCD, especially the recent advances like co-feeding effect and catalyst regeneration for augmenting the productivity of the whole process. Although a great success on the laboratory-scale has been fulfilled, TCD for greenhouse gas (GHG) free Hydrogen production is still in its infancy. The need for commercialization of TCD is greater than ever in the present situation of huge GHG emission. TCD usually examined over various kind of catalysts, such as monometallic, bimetallic, trimetallic, combination of metal–metal oxide, carbonaceous and/or metal doped carbon catalysts. Deactivation of catalysts is the prime drawback found in TCD process. Catalyst regeneration and co-feeding of methane with other hydrocarbon are the two solutions put forwarded in accordance to overcome deactivation hurdle. Higher amount of co-feed hydrocarbon in situ produce more amount of highly active carbonaceous deposits which assist further methane decomposition to produce additional Hydrogen to a great extent. The methane conversion rate increases with increase in the temperature and decreases with the flow rate in the co-feeding process in a similar manner as observed in normal TCD. The presence of co-components in the post-reaction stream is a key challenge tackled in the co-feeding and regeneration. Hence, this review hypothesizing the integration of Hydrogen Separation Membrane in to methane decomposition reactor for online Hydrogen Separation.
-
Production of greenhouse gas free Hydrogen by thermocatalytic decomposition of methane – A review
Renewable & Sustainable Energy Reviews, 2015Co-Authors: U.p.m. Ashik, Wan Mohd Ashri Wan Daud, Hazzim F AbbasAbstract:Thermocatalytic decomposition of methane (TCD) is a fully green single step technology for producing Hydrogen and nano-carbon. This review studying all development in laboratory-scale research on TCD, especially the recent advances like co-feeding effect and catalyst regeneration for augmenting the productivity of the whole process. Although a great success on the laboratory-scale has been fulfilled, TCD for greenhouse gas (GHG) free Hydrogen production is still in its infancy. The need for commercialization of TCD is greater than ever in the present situation of huge GHG emission. TCD usually examined over various kind of catalysts, such as monometallic, bimetallic, trimetallic, combination of metal–metal oxide, carbonaceous and/or metal doped carbon catalysts. Deactivation of catalysts is the prime drawback found in TCD process. Catalyst regeneration and co-feeding of methane with other hydrocarbon are the two solutions put forwarded in accordance to overcome deactivation hurdle. Higher amount of co-feed hydrocarbon in situ produce more amount of highly active carbonaceous deposits which assist further methane decomposition to produce additional Hydrogen to a great extent. The methane conversion rate increases with increase in the temperature and decreases with the flow rate in the co-feeding process in a similar manner as observed in normal TCD. The presence of co-components in the post-reaction stream is a key challenge tackled in the co-feeding and regeneration. Hence, this review hypothesizing the integration of Hydrogen Separation Membrane in to methane decomposition reactor for online Hydrogen Separation.
U. Balachandran - One of the best experts on this subject based on the ideXlab platform.
-
defect structure and transport properties of ni srceo3 δ cermet for Hydrogen Separation Membrane
Journal of The Electrochemical Society, 2005Co-Authors: Sun-ju Song, Eric D. Wachsman, L. Chen, S. E. Dorris, T H Lee, U. BalachandranAbstract:Research on Hydrogen Separation Membranes is motivated by the increasing demand for an environmentally benign, inexpensive technology for separating Hydrogen from gas mixtures. Although most studies of Hydrogen Separation Membranes have focused on proton-conducting oxides by themselves, the addition of metal to these oxides increases their Hydrogen permeability and improves their mechanical stability. This study began by determining Hydrogen permeation properties of SrCe0.8Yb0.2O3-delta (SCYb). The results showed that at the investigated temperatures (600-900 degrees C), the Hydrogen permeation rate is limited by electron flow. To further enhance Hydrogen permeability, a cermet (i.e., ceramic-metal composite) Membrane was made by adding Ni to the SCYb. At 900 degrees C, with 20% H-2/balance He as a feed gas (p(H2O) = 0.03 atm), the Hydrogen permeation rate was 0.105 cm(3)/min cm(2) for 0.25-mm-thick Ni/SCYb and 0.008 cm(3)/min cm(2) for SCYb (0.7-mm thick). The dependence of Hydrogen permeability on temperature and Hydrogen partial-pressure gradients was also determined. The proton conductivity (approximate to ambipolar conductivity) was extracted from the dependence of Hydrogen permeability on Hydrogen potential gradients. The results demonstrate that adding Ni to SCYb considerably increases its Hydrogen permeability by increasing its electron conductivity.
-
Defect Structure and Transport Properties of Ni – SrCeO3 − δ Cermet for Hydrogen Separation Membrane
Journal of The Electrochemical Society, 2005Co-Authors: Sun-ju Song, Tae H. Lee, Eric D. Wachsman, L. Chen, S. E. Dorris, U. BalachandranAbstract:Research on Hydrogen Separation Membranes is motivated by the increasing demand for an environmentally benign, inexpensive technology for separating Hydrogen from gas mixtures. Although most studies of Hydrogen Separation Membranes have focused on proton-conducting oxides by themselves, the addition of metal to these oxides increases their Hydrogen permeability and improves their mechanical stability. This study began by determining Hydrogen permeation properties of SrCe0.8Yb0.2O3-delta (SCYb). The results showed that at the investigated temperatures (600-900 degrees C), the Hydrogen permeation rate is limited by electron flow. To further enhance Hydrogen permeability, a cermet (i.e., ceramic-metal composite) Membrane was made by adding Ni to the SCYb. At 900 degrees C, with 20% H-2/balance He as a feed gas (p(H2O) = 0.03 atm), the Hydrogen permeation rate was 0.105 cm(3)/min cm(2) for 0.25-mm-thick Ni/SCYb and 0.008 cm(3)/min cm(2) for SCYb (0.7-mm thick). The dependence of Hydrogen permeability on temperature and Hydrogen partial-pressure gradients was also determined. The proton conductivity (approximate to ambipolar conductivity) was extracted from the dependence of Hydrogen permeability on Hydrogen potential gradients. The results demonstrate that adding Ni to SCYb considerably increases its Hydrogen permeability by increasing its electron conductivity.
-
Defect structure and transport properties of Ni-SrCeO3-δcermet for Hydrogen Separation Membrane
Journal of The Electrochemical Society, 2005Co-Authors: Sun-ju Song, Tae H. Lee, Eric D. Wachsman, L. Chen, S. E. Dorris, U. BalachandranAbstract:Research on Hydrogen Separation Membranes is motivated by the increasing demand for an environmentally benign, inexpensive technology for separating Hydrogen from gas mixtures. Although most studies of Hydrogen SeparationMembranes have focused on proton-conducting oxides by themselves, the addition of metal to these oxides increases their Hydrogen permeability and improves their mechanical stability. This study began by determining Hydrogen permeation properties of Srce 0 . 8 Yb 0 . 2 O 3 - δ (SCYb). The results showed that at the investigated temperatures (600-900°C), the Hydrogen permeation rate is limited by electron flow. To further enhance Hydrogen permeability, a cermet (i.e., ceramic-metal composite) Membrane was made by adding Ni to the SCYb. At 900°C, with 20% H 2 /balance He as a feed gas (pH 2 o = 0.03 atm), the Hydrogen permeation rate was 0.105 cm 3 /min cm 2 for 0.25-mm-thick Ni/SCYb and 0.008 cm 3 /min cm 2 for SCYb (0.7-mm thick). The dependence of Hydrogen permeability on temperature and Hydrogen partial-pressure gradients was also determined. The proton conductivity (ambipolar conductivity) was extracted from the dependence of Hydrogen permeability on Hydrogen potential gradients. The results demonstrate that adding Ni to SCYb considerably increases its Hydrogen permeability by increasing its electron conductivity.
-
Evaluation and Modeling of a High-temperature, High-pressure, Hydrogen Separation Membrane for Enhanced Hydrogen Production from the Water-gas Shift Reaction
Advances in Hydrogen Energy, 1Co-Authors: Robert M. Enick, Bryan D. Morreale, J. Hill, K. S. Rothenberger, A. V. Cugini, Ranjani Siriwardane, James A. Poston, U. Balachandran, Tae H. Lee, Stephen E. DorrisAbstract:A novel configuration for Hydrogen production from the water gas shift reaction is proposed, using high temperature to enhance the rate of reaction and employing a Hydrogen Separation Membrane for the collection of the high purity Hydrogen product. Experimental high-temperature, high-pressure flux measurements have been made on a material that shows promise for such an application. Mixed oxide and metal “cermet” ion-transport disk Membranes, fabricated at Argonne National Laboratory, were evaluated for Hydrogen permeability on a unique high-temperature, high-pressure test unit constructed at the National Energy Technology Laboratory. Hydrogen permeation was found to be proportional to ΔPH20.5. At 700°C, the Membrane permeability was 9.62×10−3 [cm22/min][mol/lit]0.5, or 5.63×10−9 [mol/m s Pa0.5]. The Membrane permeability increased to 3.31×10−2 [cm2/min][mol/lit]0.5, or 1.76×10−8 [mol/m s Pa0.5] at 900°C. The Membrane material was also characterized for surface changes and structural integrity using scanning electron microscopy/X-ray microanalysis, and X-ray photoelectron spectroscopy as a function of temperature, pressure, and Hydrogen exposure. Although the Membrane performed well for the short periods of time employed in this study, long-term stability remains a concern. The feasibility of using this mixed-oxide ceramic Membrane to remove Hydrogen from the reaction mixture was modeled for the optimization of the water-gas shift reaction. This reversible reaction is characterized by a very low equilibrium constant at elevated temperatures (>800°C); consequently CO conversion at these temperatures is typically less than 50%. In the scenario modeled, CO conversion was increased from 35% in the absence of a Membrane to 79% with a Membrane present, with still higher values possible if Hydrogen was actively removed from the permeate side of the Membrane. In the model, the effectiveness of the configuration is limited by the buildup of Hydrogen partial pressure on the permeate side of the Membrane. The model provided estimates of the conversion of CO attained for a specified feed, reactor size and permeate pressure.
Tatsumi Ishihara - One of the best experts on this subject based on the ideXlab platform.
-
Hydrogen production from methane using vanadium-based catalytic Membrane reactors
International Journal of Hydrogen Energy, 2013Co-Authors: Maki Matsuka, Mitoki Higashi, Tatsumi IshiharaAbstract:Abstract The application of vanadium-based Membranes as the Hydrogen Separation Membrane for a catalytic Membrane reactor system was investigated for the direct production of Hydrogen from methane. The methane conversion and Hydrogen production rates of the catalytic Membrane reactor system with Pd-coated 100 μm-thick vanadium-based Membranes were comparable with the reactor using 50 μm-thick Pd–Ag alloy Membrane at all temperatures examined. The methane conversion rates of the catalytic Membrane reactor with the Pd-coated vanadium-based Membranes were approximately 35% and 62% at 623 K and 773 K, respectively. The Hydrogen production rates were around 660 μmol min −1 at 623 K, and reached over 1710 μmol min −1 at 773 K. The relationship between the methane conversion rates and Hydrogen permeation fluxes of the catalytic Membrane reactor confirmed that the removal of Hydrogen from the reaction site enhances the methane decomposition reaction. Further, the vanadium based Membrane exhibited good stability against Fe in a Hydrogen containing atmosphere.
