Browsing by Keyword "Electroless plating"
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Item Effect of Au addition on hydrogen permeation and the resistance to H2S on Pd-Ag alloy membranes(2017) Melendez, Jon; de Nooijer, Niek; Coenen, Kai; Fernandez, Ekain; Viviente, Jose Luis; van Sint Annaland, Martin; Arias, P. L.; Tanaka, D. A.Pacheco; Gallucci, Fausto; Tecnalia Research & Innovation; TECNOLOGÍAS DE HIDRÓGENO; TECNOLOGÍA DE MEMBRANAS E INTENSIFICACIÓN DE PROCESOSIn order to make a detailed comparison between Pd-Ag and Pd-Ag-Au membranes according to their H2 permeation properties and sulfide resistance Au was deposited by the electroless plating (ELP) technique onto one half of Pd-Ag membranes. Membranes' thicknesses are ranged between 2.45 and 3.13 µm. Permeation tests have been carried out from 400 to 600 °C under single gas conditions. The Pd91.7Ag4.8Au3.5 membrane has shown a H2 permeance of 4.71·10−3 mol s−1 m−2 Pa0.5 at 600 °C, which is one of the highest values ever reported in the literature, where the Pd-Ag-Au membranes have exhibited higher hydrogen permeation rates compared to their respective Pd-Ag membranes above 550 °C. The H2 permeation properties have been determined in terms of the degree of H2S inhibition, up to 17 ppm, and subsequent H2 flux recovery rate. Pd-Ag membranes alloyed with gold resisted 12.5 h of H2S exposure showing recovery rates of 85% and 83% for Pd91.5Ag4.7Au3.8 and Pd90.5Ag4.6Au4.9 membranes, respectively, whereas the hydrogen flux of non-gold membranes decreased below detectable values. H2/N2 ideal perm-selectivity of the Pd-Ag membrane was reduced to 18 after H2S tests (starting from > 1308) while Pd-Ag-Au membranes showed a better resistance to sulfur with H2/N2 selectivity values of 793 and 121 (starting from > 4115 and > 2557 respectively). No evidence of the formation of a crystalline sulfide phase on the Pd-Ag-Au alloy membrane surfaces was found in the XRD patterns after H2S exposure and also XPS characterization did not show important changes in the composition before and after the H2S exposure tests. However, SEM images showed a decrease in the thickness of the Pd-Ag membrane and signs of corrosion and roughening on its surface, while gold-alloyed membranes did not show any damage.Item Preparation and characterization of ceramic supported ultra-thin (~1 µm) Pd-Ag membranes(2017) Melendez, Jon; Fernandez, Ekain; Gallucci, Fausto; van Sint Annaland, Martin; Arias, P. L.; Pacheco Tanaka, David A.; Tecnalia Research & Innovation; TECNOLOGÍAS DE HIDRÓGENO; TECNOLOGÍA DE MEMBRANAS E INTENSIFICACIÓN DE PROCESOSThis work reports the preparation and characterization of ultra-thin (~1 µm thick) Pd-Ag supported membranes for hydrogen purification. Ultra-thin membranes with different thicknesses (ranging from 0.46 to 1.29 µm) have been prepared by electroless plating (ELP) technique onto asymmetric tubular porous alumina supports. The membranes have been characterized by single gas and mixed gas permeation experiments at temperatures between 300 and 500 °C obtaining a correlation for the membrane permeation as a function of the activation energy and the membrane thickness. Hydrogen permeation results of the ultra-thin Pd-Ag membranes have been compared with other highly permeable membranes reported in the literature and they show some of the highest H2permeance values. A 1.29 µm thick membrane has been tested for 1000 h at 400 °C and has shown a stable H2permeance of 9.0−9.4×10−6mol m−2s−1Pa−1with a H2/N2perm-selectivity between 3300 and 2000 at 100 kPa transmembrane pressure difference. The same membrane has been tested with a feed gas mixture of H2/N2/CO with a 15% CO content and H2binary mixtures containing N2, CH4and CO2. When tested in a catalyst fluidization environment during 100 h, the 1.29 µm thick membrane showed stable H2permeance and H2/N2perm-selectivity.Item Preparation, testing and modelling of a hydrogen selective Pd/YSZ/SS composite membrane(2011-12) Sanz, R.; Calles, J. A.; Alique, D.; Furones, L.; Ordóñez, S.; Marín, P.; Corengia, P.; Fernandez, E.; GENERAL; TECNOLOGÍAS DE HIDRÓGENOA palladium selective tubular membrane has been prepared to separate and purify hydrogen. The membrane consists of a composite material, formed by different layers: a stainless steel support (thickness of 1.9 mm), an yttria-stabilized zirconia interphase (thickness of 50 μm) prepared by Atmospheric Plasma Spraying and a palladium layer (thickness of 27.7 μm) prepared by Electroless Plating. The permeation properties of the membrane have been tested at different operating conditions: retentate pressure (1-5 bar), temperature (350-450 °C) and hydrogen molar fraction of feed gas (0.7-1). At 400 °C, a permeability of 1.1 × 10-8 mol/(s m Pa 0.5) and a complete selectivity to hydrogen were obtained. The complete retention of nitrogen was maintained for all tested experiment conditions, with both single and mixtures of gases, ensuring 100% purity in the hydrogen permeate flux. A rigorous model considering all the resistances involved in the hydrogen transport has been applied for evaluating the relative importance of the different resistances, concluding that the transport through the palladium layer is the controlling one. In the same way, a model considering the axial variations of hydrogen concentration because of the cylindrical geometry of the experimental device has been applied to the fitting of the experimental data. The best fitting results have been obtained considering Sieverts'-law dependences of the permeation on the hydrogen partial pressure.Item Systematic experimental assessment of concentration polarization and inhibition in Pd-based membranes for hydrogen purification(2021-03) Tosto, Eleonora; Martinez-Diaz, David; Sanz, Raúl; Azzato, Giulia; Calles, José Antonio; Medrano, José Antonio; Fernandez, Ekain; Pacheco Tanaka, David Alfredo; Gallucci, Fausto; Alique, David; Caravella, Alessio; TECNOLOGÍAS DE HIDRÓGENO; TECNOLOGÍA DE MEMBRANAS E INTENSIFICACIÓN DE PROCESOSIn this work, we show the application of a systematic general experimental analysis to estimate in a relatively easy way the paired effects of concentration polarization and inhibition in the hydrogen permeation through diverse supported Pd-based membranes as functions of temperature and mixture composition. For this purpose, three different membranes are fabricated and tested under pure‑hydrogen and binary-mixture of H2-N2 and H2-CO. The former mixture is used to quantify the concentration polarization influence only, whereas the latter is used to quantify the overall combined effect of polarization and inhibition. Manipulating the two effects, we finally obtain the influence of inhibition only. As main results, a maximum overall permeation reduction of around 35%, 55% and 45% is evaluated for Mem#1, for Mem#2, for Mem#3, respectively. Moreover, a maximum concentration polarization coefficient of around 2.5%, 19% and 12% and a maximum inhibition coefficient of 32%, 45% and 40% are respectively evaluated. These values state the importance of having a tool able to take into account these detrimental phenomena in designing ultra-thin-membrane equipment, remarking that the same approach can be applied to other types of metal membranes as well.