Porous Stainless Steel Support Research Articles

Effect of ceria particle size as intermediate layer for preparation of composite Pd-membranes by electroless pore-plating onto porous stainless-steel supports

The use of H2-selective membranes for ultra-pure H2 production has been assigned as an attractive technology, particularly those based on Pd-films deposited onto porous stainless-steel (PSS) supports. The ability to incorporate thin Pd-films with enough adherence on any internal or external surfaces becomes essential to minimize their complexity and cost while improving their performance. The modification of original PSS substrates with diverse intermediate layers, especially those made of ceria, is presented as a promising alternative. In this context, the current study addresses for the first time the use of different CeO2 particle sizes to generate an intermediate layer and facilitate the subsequent generation of a thin Pd-film by electroless pore-plating (ELP-PP). The membrane containing the smallest CeO2 particle size (membrane S) demonstrated the lowest performance, which was assigned to the high compaction of the material and generation of cracks on its surface during calcination that consequently led to the deposition of a greater amount of Pd. On the other hand, the morphology of membranes M (medium CeO2 particle size) and L (large CeO2 particle size) were very similar, although the first one demonstrated a slightly smaller interparticle porosity, which led to the deposition of a more homogeneous and thinner Pd-film. Therefore, an outstanding performance in terms of H2 permeance (5.98 × 10−4 mol·m−2·s−1·Pa−0.5 at 400 °C) was obtained for this membrane. Permeation tests with binary mixtures (H2-N2, H2-CO2, or H2-CO) revealed a concentration-polarization effect in all cases, as well as a certain inhibition effect in the presence of CO. Finally, it should be highlighted the high stability of the membranes during the entire set of experiments, independently of the considered particle size. Thus, enough mechanical and thermal resistances can be assured for future applications.

Metal-Supported Solid Oxide Cells for Energy Conversion, Electrolysis, and Chemical Synthesis

The LBNL metal-supported solid oxide cell architecture contains zirconia electrolyte and porous backbones co-sintered between porous stainless steel supports. Advantages of this design include low-cost structural materials, mechanical ruggedness, excellent tolerance to redox cycling, and extremely fast start-up capability. These features enable a wide variety of applications including electrolysis for intermittent renewables, distributed power generation, and synthesis of valuable chemicals. Highlights from efforts in these areas are presented.

Assessment of Protective Coatings for Metal-Supported Solid Oxide Electrolysis Cells

Green hydrogen is essential to achieving carbon neutrality, and solid oxide electrolysis cells can produce hydrogen using renewable power and waste heat. Insufficient long-term durability of solid oxide electrolysis cells has impeded their commercialization. Here, coatings in the porous stainless steel support of metal-supported solid oxide electrolysis cells (MS-SOECs) are used to dramatically improve their performance and durability. The long-term degradation rate of uncoated MS-SOECs is highly dependent on the current density, with the fastest degradation occurring at the highest current density tested, 0.5 A cm–2. At this current density, coatings are quite effective. Three protective coatings, Co3O4 deposited by atomic layer deposition (ALD), Co3O4 deposited by electroplating deposition (ED), and CuMn1.8O4 (CMO) deposited by electrophoretic deposition (EPD), are explored to enhance the performance of MS-SOECs with La0.6Sr0.4Co0.2Fe0.8O3–Sm0.2Ce0.8O3 (LSCF-SDC) as the oxygen catalyst and SDC-Ni as the fuel catalyst. The initial average current density at 1.4 V is increased with coatings. It is 0.83 mA cm–2 for the ALD cells, 1.05 mA cm–2 for the ED cells, and 1.13 mA cm–2 for the EPD cells, compared to 0.65 mA cm–2 for the bare cells at 700 °C with 50% H2–50% H2O. The degradation rate over 1000 h of continuous operation is reduced from 36% to 26%, 27%, and 19% kh–1 with the three coatings, respectively. These improvements are ascribed to reduced Cr poisoning on the oxygen catalyst, which is one of the primary degradation modes for this type of MS-SOEC.

(Invited, Digital Presentation) Infiltrated Electrodes for High Temperature Energy Conversion, Electrolysis, and Chemical Synthesis

Solid oxide cell (SOC) infiltrated electrodes typically consist of a ceramic or cermet porous scaffold with the pore walls coated with catalyst particles. The pore size of the scaffold is 1 to 50 mm, whereas the catalyst particles are 10 to 300 nm. This scaffold provides a stable and durable mechanical structure, and the fine catalyst particles provide high surface area for electrochemical and heterogeneous reactions. The scaffold is sintered and bonded to the other layers of the complete cell. After this high temperature processing is finished, catalyst precursor solution is flooded into the scaffold and fired at moderate temperature to form the desired catalyst composition and phase. Because the scaffold is sintered in the absence of catalysts, re-optimization of the fabrication process, ink formulation, deposition process, and sintering protocol is not needed when a new catalyst is introduced to the cell design. Instead, a new precursor solution can be prepared from a stoichiometric mixture of metal salts, with minimal change in processing. This approach makes it straightforward to screen many catalyst compositions in a short period of time, and adapt an existing cell structure for a wide variety of applications.The Lawrence Berkeley National Laboratory metal-supported solid oxide cell (MS-SOC) design has a thin electrode scaffold of zirconia ceramic co-sintered on a thick porous stainless steel support layer. Both layers are coated with infiltrated catalysts. The catalyst precursor solution is an aqueous mixture of metal nitrate salts. After the solution is flooded into the pores of the scaffold, it is dried and heated in air to convert the nitrate salts to mixed metal oxides. The oxides can then be reduced to metals by firing in reducing atmosphere, if desired. The drying rate, heating rate, conversion temperature, and other processing parameters can have a dramatic impact on the catalyst particle morphology and ultimately on the performance and durability of the electrochemical device.Depending on the choice of catalyst composition, the MS-SOCs can be configured as fuel cells, electrolysis cells, or chemical conversion reactors. Several examples will be highlighted, including: fuel cell operation with hydrogen, ethanol, and natural gas; steam electrolysis for hydrogen production; and oxidative coupling of methane for valuable chemical synthesis. In each case, technical progress will be presented with a focus on catalyst development and device performance. Figure 1

Comprehensive permeation analysis and mechanical resistance of electroless pore-plated Pd-membranes with ordered mesoporous ceria as intermediate layer

H2-selective composite membranes, particularly those based on palladium films deposited onto porous stainless-steel supports, represent a promising technology to be practically included in both independent devices and membrane reactors. To reach thin H2-selective films and hence high permeance values, the use of a wide variety of intermediate layers is usually adopted in the literature. However, an agreement about the best solution is not found up to now. In this context, the current study presents the use of Ordered Mesoporous Ceria (OMC) particles as intermediate layer for the improvement of permeation properties of Electroless Pore-Plated (ELP-PP) Pd-composite membranes. OMC was obtained by nanocasting from SBA-15 as temporary template and cerium nitrate (III) hexahydrate as metal precursor. Resultant OMC particles have around 100 nm spherical diameter, an average pore-size diameter of 10–12 nm, and a total BET surface of around 134 m2/g. This material was next deposited onto the external surface of tubular Porous Stainless-Steel (PSS) supports by vacuum-assisted dip-coating (VA-DC) to form an intermediate layer that makes the preparation of a defect-free and thin Pd-film easier. This procedure allows the preparation of Pd composite membranes (OMC-Pd) with Pd thicknesses around 10 μm, H2 permeances of 1.03·10−3 mol m−2 s−1 Pa−0.5 at 400 °C, and high ideal selectivity αH2/N2 ≥ 24,000. It should be noted that H2 permeance has been increased up to 6 times in comparison with other ELP-PP membranes without any intermediate layer and 2 times in contrast to membranes containing dense CeO2 particles instead of the mesoporous ones for the intermediate layer. Moreover, Pd-membranes so prepared (OMC-Pd) have shown excellent mechanical resistance in a wide variety of operating conditions such as temperature, pressure, and permeate flux direction, maintaining a high H2-selectivity without delamination or peeling. These properties were also maintained in case of feeding different H2/N2 mixtures, where the concentration-polarization effect seems to stabilize for lower H2 concentration values in the feed stream, not being noticeably influenced by temperature.

Methanol steam reforming microreactor with novel 3D-Printed porous stainless steel support as catalyst support

In order to study the methanol steam reforming performance of the 3D-printed porous support for hydrogen production, three dimensional (3D) printing technology was proposed to fabricate porous stainless steel supports with body-centered cubic structure (BCCS) and face-centered cubic structure (FCCS). Catalyst loading strength of the 3D-printed porous stainless steel supports was studied. Moreover, methanol steam reforming performance of different 3D-printed porous supports for hydrogen production was experimentally investigated by changing reaction parameters. The results show that the 3D-printed porous stainless steel supports with BCCS and FCCS exhibit better catalyst loading strength, and can be used in the microreactor for methanol steam reforming for hydrogen production. Compared with 90 pores per inch (PPI) Fe-based foam support, 3D-printed porous stainless steel supports with FCCS and BCCS show the similar methanol steam reforming performance for hydrogen production in the condition of 6500 mL/(g·h) gas hourly space velocity (GHSV) with 360 °C reaction temperature. This work provides a new idea for the structural design and fabrication of the porous support for methanol steam reforming microreactor for hydrogen production.

Effects of different silica intermediate layers for hydrogen diffusion enhancement of palladium membranes applied to porous stainless steel support

Porous stainless steel (SUS) supports were modified with double intermediate layers, silicalite-1 and γ-alumina, to enhance the hydrogen diffusion of a thin palladium membrane. One of layers, silicalite-1, was prepared using the hydrothermal synthetic method on porous SUS supports. The differences in expansion/contraction behaviors caused by different thermal coefficients of expansion between silicalite-1 and the SUS resulted in a lowering of the durability of the membrane. Intermediates layers of mesoporous MCM-48 powders or commercial spherical non-porous silica particles were then applied to porous SUS supports via aspiration, γ-alumina was introduced by dip-coating, and the Pd membrane was subjected to electro-less plating. H2 permeance of the Pd membrane (membrane thickness: 11 μm) containing spherical silica particles was around 10 × 10−6 mol·m−2·s−1·Pa−1 at 600 °C, which was higher than that of the Pd membrane (membrane thickness: 7 μm) containing MCM-48. The durability of the Pd membrane containing spherical silica particles was higher than that of the version containing MCM-48 powders. These results suggest that commercial spherical non-porous silica particles will uniformly occupy the pores of the SUS tubes and enhance the H2 permeance and durability of the Pd membrane.

High performance stainless-steel supported Pd membranes with a finger-like and gap structure and its application in NH3 decomposition membrane reactor

Pd composite membranes show great potential in several important fields, such as H2 production for fuel cell or pre-combustion applications. This study presents a facile and effective approach to develop high performance stainless-steel supported Pd composite membranes with a finger-like and gap structure by coating the finger-like porous stainless-steel support (PSS) with MnCO3 particles, which forms a small gap of ca. 1 µm during subsequent thermal treatment. The stability of this novel configuration was demonstrated under 20–50 fast heating up/cooling down cycles at a maximum ramp rate of 10 K/min, under near practical fuel cell application conditions. Such a structure imitates semi-free-standing bulk Pd membranes, which not only avoids the direct contact between Pd layer and PSS and ensures a high H2 permeance, but also avoids the shear stresses between the metal membrane and module. The membrane with a finger-like and gap structure was applied in NH3 decomposition membrane reactor, which achieved nearly complete NH3 conversion at a relatively low temperature of 673 K and remained stable for 200 h, exhibiting potential in future applications.

Preparation of Pd/SAPO-34/PSS composite membranes for hydrogen separation: Effect of crystallization time on the zeolite growth on PSS support

In this study, palladium composite membranes were fabricated on porous stainless steel (PSS) supports using silicoaluminophosphate (SAPO) zeolite (SAPO-34) as a diffusion barrier and substrate modifier. The vacuum-assisted seeding and secondary growth method was used to coat the SAPO-34 zeolite layer on the PSS substrates. The morphologies and microstructures of the membranes were analyzed by AFM, XRD, BET, ICP–AES, FESEM and EDX techniques. The effect of crystallization time (24, 48 and 72h) on the morphology and quality of SAPO-34 modified supports was studied. A continuous palladium layer with a thickness of about 9μm was deposited on the SAPO-34 modified PSS support (72h crystallization time) by electroless plating (ELP) route. The hydrogen permeation tests were carried out in the feed pressures range of 2–4bar and various temperatures (623, 673 and 723K). The values of the hydrogen permeance and ideal selectivity of H2/N2 for the PSM3 membrane were achieved 7.1×10–7molm–2s–1Pa–1 and 866, respectively a feed pressure of 2bar and 723K. In addition, the PSM3 membrane showed perfect stability during 260h hydrogen permeation experiment at a feed pressure of 2bar and 623K.

Progress in Metal-Supported Solid Oxide Fuel Cells and Electrolyzers with Symmetric Metal Supports and Infiltrated Electrodes

The LBNL metal-supported solid oxide cell architecture contains zirconia electrolyte and porous backbones co-sintered between porous stainless steel supports. Advantages of this design include low-cost structural materials, mechanical ruggedness, excellent tolerance to redox cycling, and extremely fast start-up capability. With infiltrated catalysts, high performance is also achieved: 1.5 W/cm2 with hydrogen fuel and 1.3 W/cm2 with internal reforming of ethanol fuel at 700 °C; 2.6 A/cm2 electrolysis current density at 1.3V and 50% steam/50% hydrogen at 700°C. Recent approaches to mitigating catalyst coarsening and Cr deposition within the cathode stabilize the microstructure during operation. The degradation rate is improved to 2.3% kh-1 at 700°C in fuel cell mode. Electrolysis operation, however, results in higher degradation rate. Preliminary effort to fabricate metal-supported cells with proton conducting electrolyte is successful for La0.99Ca0.01NbO4 electrolyte, and specific challenges for BaZr0.7Ce0.2Y0.1O3-δ electrolyte are determined.

Stability of pore-plated membranes for hydrogen production in fluidized-bed membrane reactors

Pd-based membranes prepared by pore-plating technique have been investigated for the first time under fluidization conditions. A palladium thickness around 20 μm was achieved onto an oxidized porous stainless steel support. The stability of the membranes has been assessed for more than 1300 h in gas separation mode (no catalyst) and other additional 200 h to continuous fluidization conditions. Permeances in the order of 5·10−7 mol s−1 m−2 Pa−1 have been obtained for temperatures in a range between 375 and 500 °C. During fluidization, a small decrease in permeance is observed, as consequence of the increased external (bed-to-wall) mass transfer resistances. Moreover, water gas shift (WGS) reaction cases have been carried out in a fluidized bed membrane reactor. It has been confirmed that the selective H2 separation through the membranes resulted in CO conversions beyond the thermodynamic equilibrium (of conventional systems), showing the benefits of membrane reactors in chemical conversions.

Fabrication, characterization, and application of palladium composite membrane on porous stainless steel substrate with NaY zeolite as an intermediate layer for hydrogen purification

Palladium composite membrane with excellent stability was successfully prepared using the electroless plating (ELP) route on a porous stainless steel (PSS) support for hydrogen separation. In order to modify the average pore size of PSS support and to prevent inter-metallic diffusion, the NaY zeolite layer was coated on the PSS support with the seeding and secondary growth method. A high-temperature membrane module was designed by Solid work software and fabricated from 316 L stainless steel with a knife-edge seal. The microstructures and morphologies of the samples were analyzed using XRD, BET, AFM, FESEM and EDX techniques. Permeation experiments were carried out with binary mixtures of H2/N2 with various ratios (90/10, 75/25 and 50/50) and pure H2 and N2 at different temperatures (350, 400 and 450 °C) and feed pressures (200–400 kPa). Hydrogen permeation tests showed that the membrane with a thickness of about 7 μm had a hydrogen permeance of 6.2 × 10−4 mol m−2 s−1 Pa−0.5 with an ideal H2/N2 selectivity of 736, at 450 °C. In addition, the results of stability tests revealed that the membrane could remain stable during a long-term operation by varying temperature and feed gases.

Hydrogen production via natural gas steam reforming in a Pd-Au membrane reactor. Comparison between methane and natural gas steam reforming reactions

High-purity hydrogen to be fed directly to a PEMFC was produced by carrying out natural gas steam reforming under moderate operating conditions in a Pd-Au composite membrane reactor packed with a commercial Ni-based catalyst. The Pd-Au composite membrane with a thickness of approximately 12 µm was fabricated by using both electroless and electroplating techniques to deposit Pd and Au layers, respectively, over a porous stainless-steel support. After annealing, the membrane showed a hydrogen permeance of 1.30 × 10−3 mol/s-m2-Pa0.5 at 450 °C, and near-infinite ideal selectivity of H2/Ar at pressures lower than 300 kPa and at temperatures lower than 400 °C. The natural gas reforming reaction was performed at 450 °C with a steam-to-methane ratio of 3.5 and gas hourly space velocity of 2600 h−1 at different operating pressures varying from 100 kPa to 300 kPa. As a comparison, the steam methane reforming reaction was also carried out at the same operating conditions.The natural gas reforming reaction showed better performance than the steam methane reforming reaction and reached > 80% conversion of the higher hydrocarbons and almost 65% of hydrogen recovery at 450 °C and 300 kPa. High-purity hydrogen was obtained in all the experimental tests. No coke formation was observed. Post-reaction analysis of the membrane is discussed via scanning electron microscope and energy-dispersive X-ray spectroscopy.

Hydrogen production by steam methane reforming in membrane reactor equipped with Pd membrane deposited on NiO/YSZ/NiO multilayer-treated porous stainless steel

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.

Supported Zeolite Beta Layers via an Organic Template-Free Preparation Route.

Layers of high silica zeolites, synthesized with an organic structure directing agent (OSDA) and grown onto porous support structures, frequently suffer from the thermal stress during the removal of OSDA via the calcination process. The different thermal expansion coefficients of the zeolite and the support material, especially when stainless steel is used as a support, causes enormous tension resulting in defect formation in the zeolite layer. However, the calcination is an easy procedure to decompose the OSDA in the pore system of the zeolite. Recently, methods to synthesize zeolite beta without the use of an organic structure directing agent have been described. In the present study, a seed-directed synthesis is used to prepare OSDA-free zeolite beta layers on stainless steel supports via an in situ preparation route. For the application as membrane, a porous stainless steel support has been chosen. The beta/stainless steel composites are characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). To prove its possible application as a membrane, the beta/stainless steel composites were also tested by single gas permeances of H2, He, CO2, N2, and CH4.

Influence of the selective layer morphology on the permeation properties for Pd-PSS composite membranes prepared by electroless pore-plating: Experimental and modeling study

Abstract This work analyzes the relationship between hydrogen permeation behavior and palladium layer morphology, particularly taking into account the palladium introduction into the pores for composite membranes prepared by Electroless Pore-Plating (ELP-PP) over porous stainless steel supports. Fully dense membranes have been achieved with hydrogen permeances in the range 7 - 18 · 10 - 5 mol / m 2 s Pa 0.5 by varying the hydrazine concentration used for the palladium plating. Permeation measurements for pure gases and mixtures have been carried out at different conditions: pressure driving force, temperature and feed composition. Both morphology and permeation properties are clearly influenced by the concentration of hydrazine, used as reducing agent during the ELP-PP process. In this manner, higher hydrazine concentrations provoke the formation of thicker external palladium films and, consequently, the reduction of both external porosity and roughness. On the other side, lower hydrazine concentrations reduce the required amount of palladium to obtain a fully dense membrane. In the last case, however, part of palladium is introduced into the pores of the support in a huger extension. This fact, in turns, generates an additional hydrogen permeation resistance, which diminishes the permeation flux and introduces a threshold in the minimum trans-membrane pressure value required for a hydrogen permeate flux. A new mathematical model, based on the classical Sieverts’ law, is proposed to predict this particular behavior by including a new fitting parameter defined as the ratio of the gas-palladium surface in both retentate and permeate sides of the membrane. This new parameter has been denoted as η , achieving good accuracy between both predicted and experimental data when considering the gap in the trans-membrane pressure. Therefore, the presented model can be used in multiple cases to design and optimize membranes modules, whereas the retentate and permeate gas-palladium surface ratio will be different, as for instance in case of palladium is introduced partially into the pores of supports.

Fabrication of metal–ceramic membranes withstanding extreme operating conditions

Preparation of bilayer metal–ceramic membranes with porous stainless steel supports and selective layers based on TiO2 has been described. The resulting membranes have high air and distilled water fluxes. Pressure-hold tests have shown that the experimental samples of stainless steel supports withstand pressure drop up to 1.9 MPa. Toxicological tests showed the possibility of using these membranes in medical industry. These membranes can be used for microfiltration in hot corrosive environments as high-efficiency filters in chemical and microbiological industries and fine filters in food production processes, membrane sterilization, and other fields.

Porous stainless steel support for hydrogen separation Pd membrane; fabrication by metal injection molding and simple surface modification

We prepared a disc-shaped porous stainless steel (PSS) support for hydrogen separation Pd membrane via metal injection molding (MIM) method to facilitate the mass production of porous substrates. MIMed PSS supports obtained in a batch showed relatively higher apparent porosity (from 32.75% to 39.28%) than that reported for commercially available PSS substrate. In addition, the surface morphologies of the MIMed PSS, surface roughness of 1.119 μm and pore depth of 8.6 μm, indicate its suitability as a membrane support than the commercially available one. Pd membrane prepared over MIMed PSS, which was modified by a simple axial pressing method to control the surface morphologies, had a thinner Pd layer, 2.94 μm, and showed an extremely higher ideal H2/N2 selectivity with a hydrogen permeation flux of 21.3 ml/min/cm2 at del-P = 1 bar and 400 °C, compared with Pd membrane over MIMed PSS modified with conventional surface modification.

금속 사출성형 방식의 다공성 스테인리스 강 지지체에 형성된 팔라듐 수소 분리막의 투과 선택도 특성

금속 사출성형 방식의 다공성 스테인리스 강 지지체에 형성된 팔라듐 수소 분리막의 투과 선택도 특성

Diffusion barrier coating using a newly developed blowing coating method for a thermally stable Pd membrane deposited on porous stainless-steel support

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 H2/N2 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.