The Experts below are selected from a list of 3954 Experts worldwide ranked by ideXlab platform
Shinkun Ryi - One of the best experts on this subject based on the ideXlab platform.
-
hydrogen production by steam methane reforming in membrane reactor equipped with pd membrane deposited on nio ysz nio multilayer treated Porous Stainless Steel
Journal of Membrane Science, 2018Co-Authors: Chang Hyun Kim, Jaeyun Han, Hankwon Lim, Kwan Young Lee, Shinkun RyiAbstract:Abstract In this study, we prepared a Pd composite membrane with high hydrogen permeance and thermal stability on a tubular Porous Stainless Steel (PSS) support by ethylene diamine tetraacetic acid-free electroless plating. The conventional yttria-stabilized zirconia (YSZ) was replaced with a NiO/YSZ/NiO multilayer as the diffusion barrier, and the latter was introduced on a PSS tube (diameter of 12.7 mm, length of 450 mm, and surface area of 175 cm2). A long-term thermal stability test revealed that the NiO/YSZ/NiO multilayer significantly reduced the growth rate of nitrogen leakage. The test was carried out for ~1150 h on a 2.5-µm thick Pd membrane deposited on a NiO/YSZ/NiO/PSS tube (diameter of 25.4 mm, length of 450 mm, and surface area of 350 cm2). The hydrogen permeance obtained at the end of the test was 3.81 × 10−3 mol m−2 s−1 Pa−0.5, and the H2/N2 selectivity was ~87 at a temperature of 773 K and pressure difference of 101.3 kPa. The rate of increase in nitrogen leakage during the test was 3.05 × 10–11 mol m−2 s−1 Pa−0.5 h−1, which demonstrated the ability of the NiO/YSZ/NiO multilayer to mitigate nitrogen leakage. To produce hydrogen using the Pd composite membrane reactor, steam methane reforming was conducted under the following operating conditions: pressure, 430–1114 kPa; temperature, 883 K; and gas hourly space velocity, 1000 h−1. The reaction yielded a methane conversion and hydrogen recovery of 75.1% and 97.9%, respectively. The permeate stream was composed of 93.1 vol% H2, 0.6 vol% CO, 1.8 vol% CH4, and 4.5 vol% CO2. The gas composition of the permeate stream was suitable for use as fuel in a high-temperature polymer electrolyte membrane fuel cell.
-
palladium ruthenium composite membrane for hydrogen separation from the off gas of solar cell production via chemical vapor deposition
Journal of Membrane Science, 2017Co-Authors: Sang Moon Lee, Shinkun Ryi, John R Grace, Tony Boyd, Sung Su Kim, Jim C Lim, Alexander Susdorf, Achim SchaadtAbstract:Abstract The potential application of palladium-ruthenium composite membranes to the separation of hydrogen from chlorosilane gases in silicon-based industries was investigated. Palladium and palladium-ruthenium composite membranes were deposited on pretreated Porous Stainless Steel substrates by electroless plating. Hydrogen permeation tests and temperature programmed desorption (TPD) analysis revealed that the addition of a Ru overlayer on Pd changed the hydrogen adsorption characteristics, resulting in improved stability of the membrane at low temperatures. The Ru/Pd/Al 2 O 3 /PSS composite membrane had a stable hydrogen permeation flux of 1.8 m 3 m −2 h −1 over a period of 1200 h at 180 °C without suffering hydrogen embrittlement. After exposure to impurities such as HCl and SiHCl 3 , the hydrogen permeation flux of the Ru/Pd/Al 2 O 3 /PSS composite membrane was stable over a period of 9 h with feed pressure of 2.0 bar at 225 °C. Scanning electron microscopy (SEM), energy dispersive X-ray (EDX), and EDX mapping of the Ru/Pd/Al 2 O 3 /PSS membrane after the exposure test showed no surface deposition of Si and Cl.
-
diffusion barrier coating using a newly developed blowing coating method for a thermally stable pd membrane deposited on Porous Stainless Steel support
International Journal of Hydrogen Energy, 2017Co-Authors: Chang Hyun Kim, Jaeyun Han, Hankwon Lim, Kwan Young Lee, Shinkun RyiAbstract:Abstract In this study, we present an intermetallic diffusion barrier coating using a newly developed blowing coating method for a thermally stable Pd-based composite membrane on Porous Stainless Steel (PSS). A tubular PSS sample with 1/2 inch (12.7 mm) in diameter and 450 mm in length was used for the support. The support was welded with a Stainless-Steel cap and a 450-mm-long Stainless-Steel tube for each end. Before the diffusion barrier coating, the large-sized entrance pores were gradually blocked with sub-micron (∼500 nm) and nano (50–80 nm) yttria stabilized zirconia (YSZ). 8YSZ, i.e., 8wt.% YSZ, was used for the interdiffusion barrier material and dispersed on the surface of the pre-treated PSS using the blowing coating method. The blowing coating method has 4 steps: (i) spraying the 17 wt. % 8YSZ paste on the surface of the PSS tube, (ii) blowing the paste using compressed air, (iii) drying at room temperature, and (iv) heat treatment at 923 K for 2 h in air. Steps (i) and (ii) were repeated 3 times to have a ∼240 nm thick 8YSZ layer. A thin palladium layer (∼3 μm) was deposited on the pre-treated PSS using electroless plating, and the membrane stability was tested at 673–773 K for ∼ 200 h. A hydrogen permeation flux of 9.86 × 10 −2 mol m −2 s −1 and an H 2 /N 2 selectivity of 595 were obtained at 773 K and a transmembrane pressure difference of 20 kPa. The surface and cross-sectional SEM/EDX analysis confirmed that the 8YSZ layer sufficiently prevented the interdiffusion between Pd and PSS elements, such as Fe, Cr and Ni.
-
development of homogeneous pd ag alloy membrane formed on Porous Stainless Steel by multi layered films and ag upfilling heat treatment
Journal of Membrane Science, 2015Co-Authors: Junhyung Lee, Shinkun Ryi, Jaeyun Han, Kyungmin Kim, Dongwon KimAbstract:Abstract Intermetallic diffusion between the Pd layer and the Porous metal support can limit the hydrogen permeability, and ultimately give rise to serious problems in the long-term stability of Pd alloy hydrogen separation membranes. In this study, we developed a multi-layered Pd–Ag membrane having a uniform-microstructure and thermally stable alloy composition by DC magnetron sputtering and Ag up-filling heat treatment. This multi-layered Pd–Ag alloy membrane was introduced in order to prevent Ag segregation, to block the intermetallic diffusion from the Porous Stainless Steel (PSS), and to improve the stability of the membrane. Experimental results showed that the homogeneous Pd–Ag alloy membranes acted as an extremely effective diffusion barrier and provided significant improvement on the thermal stability over a period of 2000 h.
-
electroless plating of pd after shielding the bottom of planar Porous Stainless Steel for a highly stable hydrogen selective membrane
Journal of Membrane Science, 2014Co-Authors: Shinkun Ryi, Sungwook Lee, Beomseok Seo, Jinwoo Park, Jongsoo Park, Dongwook Lee, Sung Su KimAbstract:Abstract This study demonstrates that thermally stable palladium membranes can be electrolessly plated on ZrO 2 modified planar Porous Stainless Steel (PSS) with EDTA-free bath following a palmitic acid treatment. Prior to elctrroless plating of palladium with EDTA-free bath, the bottom of the ceramic-modified planar Porous Stainless Steel (PSS) was shielded by a palmitic acid prior to palladium plating to prevent the diffusion of the plating solution through the bottom of the substrate that causes palladium plating in the pores of the PSS. The hydrogen permeation flux and the nitrogen leakage were monitored for an extended period of time at a pressure difference of 100 kPa and 873 K and showed that the palmitic acid-treatment provided membrane stability at high-temperature.
L M Cornaglia - One of the best experts on this subject based on the ideXlab platform.
-
naa zeolite membranes synthesized on top of aptes modified Porous Stainless Steel substrates
Journal of Membrane Science, 2016Co-Authors: Yohana Martinez Galeano, L M Cornaglia, Ana Maria TarditiAbstract:Fil: Martinez Galeano, Yohana. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Santa Fe. Instituto de Investigaciones en Catalisis y Petroquimica "Ing. Jose Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catalisis y Petroquimica "Ing. Jose Miguel Parera"; Argentina
-
pdau membranes supported on top of vacuum assisted zro2 modified Porous Stainless Steel substrates
Journal of Membrane Science, 2013Co-Authors: Ana Maria Tarditi, Camila Gerboni, L M CornagliaAbstract:Abstract To enable the formation of defect-free PdAu composites by electroless plating, the vacuum-assisted ZrO 2 -modified method was optimized on top of Porous Stainless Steel disks. Both the ZrO 2 -modified supports and the PdAu synthesized membranes were characterized by XRD (X-ray diffraction), SEM (scanning electron microscopy), EDS (energy dispersive X-ray analysis) and XPS (X-ray photoelectron spectroscopy). SEM cross-section results showed that dense, continuous, defect-free PdAu films were deposited on top of the ZrO 2 -modified PSS disks, and the EDS data indicated that no significant concentration gradient was present on the thickness. At 400 °C and 100 kPa, the pure hydrogen permeation flux for a 10 μm thick PdAu membrane was about 0.14 mol s −1 m −2 and the H 2 /N 2 ideal selectivity was higher than 10,000.
-
dry reforming of methane in membrane reactors using pd and pd ag composite membranes on a naa zeolite modified Porous Stainless Steel support
Journal of Membrane Science, 2010Co-Authors: Maria Laura Bosko, E A Lombardo, John Munera, L M CornagliaAbstract:Abstract This paper reports the results obtained with different composite membranes used on a membrane reactor for the production of high purity hydrogen. The dry reforming of methane was carried out over a Rh/La 2 O 3 catalyst. Two types of composite membranes were synthesized, Pd and a Pd–Ag alloy. The metal films were deposited by electroless plating on modified Porous Stainless Steel. The support surface was previously modified with a NaA zeolite by dip coating and hydrothermal synthesis. The composition and crystalline structures of the alloy films were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDS), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The membrane reactor was designed and built to use either the Pd or the Pd–Ag composite membrane whose crystalline structure and typical morphology were not affected after different reaction conditions. The Pd membrane showed the best behavior in the membrane reactor with the highest methane conversion, H 2 /CH 4 selectivity and permeation flux. After operation of the membranes at 450–500 °C on stream for up to 570 h no modification of the permeation parameters was observed.
-
naa zeolite as an effective diffusion barrier in composite pd pss membranes
Journal of Membrane Science, 2009Co-Authors: Maria Laura Bosko, E A Lombardo, F Ojeda, L M CornagliaAbstract:Abstract Palladium composite membranes on Porous Stainless Steel were prepared by electroless plating. In order to obtain a thin palladium film, an intermediate layer was necessary to modify the pore size of the substrate and form a diffusion barrier between the palladium film and the support. The NaA zeolite, used as intermediate, was synthesized by vacuum-assisted secondary growth. Pure gas permeability tests were conducted using hydrogen and nitrogen between 400 and 450 °C. The surface morphology and the components of the different layers of the membrane were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDS), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). When vacuum was applied during the zeolite synthesis at 80 °C, the Pd membrane showed high H2/N2 ideal selectivity in the working temperature range. This result suggests that NaA zeolite is an effective intermediate substrate modifier when an appropriate synthesis method is employed.
-
characterization of pd ag membranes after exposure to hydrogen flux at high temperatures
Journal of Membrane Science, 2007Co-Authors: Maria Laura Bosko, David Yepes, Silvia Irusta, Pierre Eloy, Patricio Ruiz, E A Lombardo, L M CornagliaAbstract:Pd-Ag films were deposited by sequential electroless plating on Porous Stainless Steel tubes. Two different intermediate layers of alpha-Fe2O3 and gamma-Al2O3 oxides were employed as diffusion barriers to modify the Stainless Steel Porous size and to avoid the intermetallic diffusion of Fe and Ni through the Pd-Ag layer. The membranes were tested in a gas permeation system to determine the hydrogen permeability and selectivity at temperatures between 673 and 923 K. After the high temperature treatments, they were characterized by XRD, XPS, SEM, AFM and EPMA. The Pd-Ag/PSS membranes had a good thermal resistance. After annealing at 923 K, the Auger depth profiles did not show the presence of Fe in the Pd-Ag/gamma-Al2O3 membranes. However, iron was detected in the surface layer after long-term hydrogen permeation measurements at temperatures between 673 and 923 K, indicating that the gamma-Al2O3 layer did not completely block the intermetallic diffusion under these severe conditions. (C) 2007 Elsevier B.V. All rights reserved.
Yi Hua - One of the best experts on this subject based on the ideXlab platform.
-
hydrogen production in a large scale water gas shift pd based catalytic membrane reactor
Industrial & Engineering Chemistry Research, 2013Co-Authors: Jacopo Catalano, Ivan P Mardilovich, Federico Guazzone, Nikolaos Kazantzis, Yi HuaAbstract:Composite palladium and Pd-based membranes represent an appealing technology option to increase the CO conversion and the H2 recovery in the water–gas shift (WGS) reactor as a result of the continuous removal of hydrogen over the course of the reaction. Even though many studies have been performed in this area, their outcome typically represents a proof-of-concept involving reactors with small membrane area. The present study therefore addresses the scaling up of the process to obtain high hydrogen production rates through the use of large surface area, ∼0.02 m2, composite Pd membranes. Two thin, δ < 10 μm, defect-free composite membranes were prepared by the electroless plating method on Porous Stainless Steel tubular supports and tested under pure gases and water–gas shift reaction conditions. Syngas similar to the actual gasifier reacting mixture (40% H2, 42.2% CO, and 17.8% CO2 and steam to carbon ratio varying between 2.5 and 3.5) was fed to the WGS catalytic membrane reactor (WGS-CMR) with a total f...
-
chromium oxide intermetallic diffusion barrier for palladium membrane supported on Porous Stainless Steel
Journal of Membrane Science, 2010Co-Authors: Sutheerawat Samingprai, Supawan Tantayanon, Yi HuaAbstract:Abstract Dense palladium membrane on oxidized Porous Stainless Steel (oxPSS) tube was prepared. Its hydrogen permeance was observed to decline at the temperature higher than 400 °C. SEM–EDX analysis of the cross-section of the annealed tube at 500 °C indicated the occurrence of the intermetallic diffusion. The heat treatment study of the palladium membrane on oxPSS disks in hydrogen atmosphere at various temperatures was essentially carried out. Their SEM–EDX analysis results confirmed that the in situ metal oxide barrier could not inhibit the intermetallic diffusion in hydrogen atmosphere. The chromium oxide layers at different thicknesses were then developed on oxPSS disks before palladium plating by controlled chromium elctrodeposition followed by oxidation in air at 700 °C. The similar heat treatment study and SEM–EDX analysis of these disks revealed that the presence of chromium oxide layer could suppress the intermetallic diffusion. Then, the dense palladium membrane tube with chromium oxide layer was prepared and its heat treatment in hydrogen atmosphere was studied. The result showed the steady increase in hydrogen permeance with increasing temperature.
-
microstructure analysis of the intermetallic diffusion induced alloy phases in composite pd ag Porous Stainless Steel membranes
Industrial & Engineering Chemistry Research, 2007Co-Authors: Engin M Ayturk, Erik E Engwall, Yi HuaAbstract:The surface interactions and associated phase changes of the annealed electroless plated Pd and Ag on Porous Stainless Steel (PSS) supports were investigated in the temperature range of 500−800 °C....
-
synthesis of composite pd Porous Stainless Steel pss membranes with a pd ag intermetallic diffusion barrier
Journal of Membrane Science, 2006Co-Authors: Engin M Ayturk, Ivan P Mardilovich, Erik E Engwall, Yi HuaAbstract:Abstract Intermetallic diffusion of support elements (Fe, Cr and Ni) into the membrane layer during high temperature hydrogen separation applications is a key factor affecting the overall performance of Pd and Pd/Ag membranes supported on Porous sintered metals. Pd/Ag membranes supported on Porous Stainless Steel (PSS) supports were prepared by the bi-metal multi-layer (BMML) deposition technique, which involved the formation of a Porous Pd–Ag composite layer by consecutive deposition of Pd and Ag layers with no intermediate surface activation. While the conventional electroless plating involved intermediate drying and activating steps between Pd and Ag depositions, BMML deposition provided continuous plating with alternating Pd and Ag baths. The synthesis of these membranes involved a finishing step of the application of a gas tight Pd layer upon the BMML giving the membrane high hydrogen selectivity and long-term durability due to the fact that the BMML formed an extremely effective intermetallic diffusion barrier. Several membranes prepared by this technique have been stable under hydrogen permeation conditions for over 500 h at temperatures exceeding 500 °C. He flux data and SEI micrographs, prior to application of the Pd top coat, showed that the BMML formed a graded support, without significantly changing the total resistance of the support. In addition, heat treatment studies coupled with the X-ray phase identification analysis showed the formation of a Pd/Ag alloy phase, which might further improve the hydrogen permeability.
-
effects of surface activity defects and mass transfer on hydrogen permeance and n value in composite palladium Porous Stainless Steel membranes
Catalysis Today, 2006Co-Authors: Federico Guazzone, Erik E Engwall, Yi HuaAbstract:Abstract The H 2 permeance of composite palladium-Porous Stainless Steel (Pd-PSS) membranes was determined: (1) by assuming Sieverts’ law ( n = 0.5) and (2) by performing a non-linear fit in order to obtain the hydrogen permeance and the n -value. For all membranes (thickness > 15 μm) the n -value was higher than 0.6 at low temperatures ( 400 °C). The activation of the membrane with the surface either seeded with palladium or oxidized in air at 350 °C for 48 h led to lower n -values indicating that the surface reaction rate even in thick membranes with selectivities (H 2 /He) above 400 might still contribute, though to a minor extent, to the overall hydrogen permeation mechanism. For leaky membranes (selectivity ≪ 400) the Knudsen diffusion and viscous flow of molecular H 2 through the defects led to n -values as high as 0.75 at 500 °C. n -Values higher than 0.5 were also found for Pd-PSS membranes when the PSS support had a large resistance.
Jaeyun Han - One of the best experts on this subject based on the ideXlab platform.
-
hydrogen production by steam methane reforming in membrane reactor equipped with pd membrane deposited on nio ysz nio multilayer treated Porous Stainless Steel
Journal of Membrane Science, 2018Co-Authors: Chang Hyun Kim, Jaeyun Han, Hankwon Lim, Kwan Young Lee, Shinkun RyiAbstract:Abstract In this study, we prepared a Pd composite membrane with high hydrogen permeance and thermal stability on a tubular Porous Stainless Steel (PSS) support by ethylene diamine tetraacetic acid-free electroless plating. The conventional yttria-stabilized zirconia (YSZ) was replaced with a NiO/YSZ/NiO multilayer as the diffusion barrier, and the latter was introduced on a PSS tube (diameter of 12.7 mm, length of 450 mm, and surface area of 175 cm2). A long-term thermal stability test revealed that the NiO/YSZ/NiO multilayer significantly reduced the growth rate of nitrogen leakage. The test was carried out for ~1150 h on a 2.5-µm thick Pd membrane deposited on a NiO/YSZ/NiO/PSS tube (diameter of 25.4 mm, length of 450 mm, and surface area of 350 cm2). The hydrogen permeance obtained at the end of the test was 3.81 × 10−3 mol m−2 s−1 Pa−0.5, and the H2/N2 selectivity was ~87 at a temperature of 773 K and pressure difference of 101.3 kPa. The rate of increase in nitrogen leakage during the test was 3.05 × 10–11 mol m−2 s−1 Pa−0.5 h−1, which demonstrated the ability of the NiO/YSZ/NiO multilayer to mitigate nitrogen leakage. To produce hydrogen using the Pd composite membrane reactor, steam methane reforming was conducted under the following operating conditions: pressure, 430–1114 kPa; temperature, 883 K; and gas hourly space velocity, 1000 h−1. The reaction yielded a methane conversion and hydrogen recovery of 75.1% and 97.9%, respectively. The permeate stream was composed of 93.1 vol% H2, 0.6 vol% CO, 1.8 vol% CH4, and 4.5 vol% CO2. The gas composition of the permeate stream was suitable for use as fuel in a high-temperature polymer electrolyte membrane fuel cell.
-
diffusion barrier coating using a newly developed blowing coating method for a thermally stable pd membrane deposited on Porous Stainless Steel support
International Journal of Hydrogen Energy, 2017Co-Authors: Chang Hyun Kim, Jaeyun Han, Hankwon Lim, Kwan Young Lee, Shinkun RyiAbstract:Abstract In this study, we present an intermetallic diffusion barrier coating using a newly developed blowing coating method for a thermally stable Pd-based composite membrane on Porous Stainless Steel (PSS). A tubular PSS sample with 1/2 inch (12.7 mm) in diameter and 450 mm in length was used for the support. The support was welded with a Stainless-Steel cap and a 450-mm-long Stainless-Steel tube for each end. Before the diffusion barrier coating, the large-sized entrance pores were gradually blocked with sub-micron (∼500 nm) and nano (50–80 nm) yttria stabilized zirconia (YSZ). 8YSZ, i.e., 8wt.% YSZ, was used for the interdiffusion barrier material and dispersed on the surface of the pre-treated PSS using the blowing coating method. The blowing coating method has 4 steps: (i) spraying the 17 wt. % 8YSZ paste on the surface of the PSS tube, (ii) blowing the paste using compressed air, (iii) drying at room temperature, and (iv) heat treatment at 923 K for 2 h in air. Steps (i) and (ii) were repeated 3 times to have a ∼240 nm thick 8YSZ layer. A thin palladium layer (∼3 μm) was deposited on the pre-treated PSS using electroless plating, and the membrane stability was tested at 673–773 K for ∼ 200 h. A hydrogen permeation flux of 9.86 × 10 −2 mol m −2 s −1 and an H 2 /N 2 selectivity of 595 were obtained at 773 K and a transmembrane pressure difference of 20 kPa. The surface and cross-sectional SEM/EDX analysis confirmed that the 8YSZ layer sufficiently prevented the interdiffusion between Pd and PSS elements, such as Fe, Cr and Ni.
-
development of homogeneous pd ag alloy membrane formed on Porous Stainless Steel by multi layered films and ag upfilling heat treatment
Journal of Membrane Science, 2015Co-Authors: Junhyung Lee, Shinkun Ryi, Jaeyun Han, Kyungmin Kim, Dongwon KimAbstract:Abstract Intermetallic diffusion between the Pd layer and the Porous metal support can limit the hydrogen permeability, and ultimately give rise to serious problems in the long-term stability of Pd alloy hydrogen separation membranes. In this study, we developed a multi-layered Pd–Ag membrane having a uniform-microstructure and thermally stable alloy composition by DC magnetron sputtering and Ag up-filling heat treatment. This multi-layered Pd–Ag alloy membrane was introduced in order to prevent Ag segregation, to block the intermetallic diffusion from the Porous Stainless Steel (PSS), and to improve the stability of the membrane. Experimental results showed that the homogeneous Pd–Ag alloy membranes acted as an extremely effective diffusion barrier and provided significant improvement on the thermal stability over a period of 2000 h.
Chang Hyun Kim - One of the best experts on this subject based on the ideXlab platform.
-
hydrogen production by steam methane reforming in membrane reactor equipped with pd membrane deposited on nio ysz nio multilayer treated Porous Stainless Steel
Journal of Membrane Science, 2018Co-Authors: Chang Hyun Kim, Jaeyun Han, Hankwon Lim, Kwan Young Lee, Shinkun RyiAbstract:Abstract In this study, we prepared a Pd composite membrane with high hydrogen permeance and thermal stability on a tubular Porous Stainless Steel (PSS) support by ethylene diamine tetraacetic acid-free electroless plating. The conventional yttria-stabilized zirconia (YSZ) was replaced with a NiO/YSZ/NiO multilayer as the diffusion barrier, and the latter was introduced on a PSS tube (diameter of 12.7 mm, length of 450 mm, and surface area of 175 cm2). A long-term thermal stability test revealed that the NiO/YSZ/NiO multilayer significantly reduced the growth rate of nitrogen leakage. The test was carried out for ~1150 h on a 2.5-µm thick Pd membrane deposited on a NiO/YSZ/NiO/PSS tube (diameter of 25.4 mm, length of 450 mm, and surface area of 350 cm2). The hydrogen permeance obtained at the end of the test was 3.81 × 10−3 mol m−2 s−1 Pa−0.5, and the H2/N2 selectivity was ~87 at a temperature of 773 K and pressure difference of 101.3 kPa. The rate of increase in nitrogen leakage during the test was 3.05 × 10–11 mol m−2 s−1 Pa−0.5 h−1, which demonstrated the ability of the NiO/YSZ/NiO multilayer to mitigate nitrogen leakage. To produce hydrogen using the Pd composite membrane reactor, steam methane reforming was conducted under the following operating conditions: pressure, 430–1114 kPa; temperature, 883 K; and gas hourly space velocity, 1000 h−1. The reaction yielded a methane conversion and hydrogen recovery of 75.1% and 97.9%, respectively. The permeate stream was composed of 93.1 vol% H2, 0.6 vol% CO, 1.8 vol% CH4, and 4.5 vol% CO2. The gas composition of the permeate stream was suitable for use as fuel in a high-temperature polymer electrolyte membrane fuel cell.
-
diffusion barrier coating using a newly developed blowing coating method for a thermally stable pd membrane deposited on Porous Stainless Steel support
International Journal of Hydrogen Energy, 2017Co-Authors: Chang Hyun Kim, Jaeyun Han, Hankwon Lim, Kwan Young Lee, Shinkun RyiAbstract:Abstract In this study, we present an intermetallic diffusion barrier coating using a newly developed blowing coating method for a thermally stable Pd-based composite membrane on Porous Stainless Steel (PSS). A tubular PSS sample with 1/2 inch (12.7 mm) in diameter and 450 mm in length was used for the support. The support was welded with a Stainless-Steel cap and a 450-mm-long Stainless-Steel tube for each end. Before the diffusion barrier coating, the large-sized entrance pores were gradually blocked with sub-micron (∼500 nm) and nano (50–80 nm) yttria stabilized zirconia (YSZ). 8YSZ, i.e., 8wt.% YSZ, was used for the interdiffusion barrier material and dispersed on the surface of the pre-treated PSS using the blowing coating method. The blowing coating method has 4 steps: (i) spraying the 17 wt. % 8YSZ paste on the surface of the PSS tube, (ii) blowing the paste using compressed air, (iii) drying at room temperature, and (iv) heat treatment at 923 K for 2 h in air. Steps (i) and (ii) were repeated 3 times to have a ∼240 nm thick 8YSZ layer. A thin palladium layer (∼3 μm) was deposited on the pre-treated PSS using electroless plating, and the membrane stability was tested at 673–773 K for ∼ 200 h. A hydrogen permeation flux of 9.86 × 10 −2 mol m −2 s −1 and an H 2 /N 2 selectivity of 595 were obtained at 773 K and a transmembrane pressure difference of 20 kPa. The surface and cross-sectional SEM/EDX analysis confirmed that the 8YSZ layer sufficiently prevented the interdiffusion between Pd and PSS elements, such as Fe, Cr and Ni.