Pd–Cu–M (M = Y, Ti, Zr, V, Nb, and Ni) Alloys for the Hydrogen Separation Membrane

Abstract

Self-supported fcc Pd-Cu-M (M = Y, Ti, Zr, V, Nb, and Ni) alloys were studied as potential hydrogen purification membranes. The effects of small additions (1-2.6 at. %) of these elements on the structure, hydrogen solubility, diffusivity, and permeability were examined. Structural analyses by X-ray diffraction (XRD) showed the fcc phase for all alloys with induced textures from cold rolling. Heat treatment at 650 °C for 96 h led to the reorientation in all alloys except the Pd-Cu-Zr alloy, exhibiting the possibility to enhance the structural stability by Zr addition. Hydrogen solubility was almost doubled in the ternary alloys containing Y and Zr compared to PdCu alloy at 300 °C. It was noted that hydrogen diffusivity is decreased upon additions of these elements compared to the PdCu alloy, with the Pd-Cu-Zr alloy showing the lowest hydrogen diffusivity. However, the comparable hydrogen permeability of the Pd-Cu-Zr alloy with the corresponding binary alloy, as well as its highest hydrogen permeability among the studied ternary alloys at temperatures higher than 300 °C, suggested that hydrogen permeation of these alloys within the fcc phase is mainly dominated by hydrogen solubility. Hydrogen flux variations of all ternary alloys were studied and compared with the PdCu alloy under 1000 ppm of HS + H feed gas. Pd-Cu-Zr alloy showed superior resistance to the sulfur poisoning probably due to the less favorable HS-surface interaction and more importantly slower rate of bulk sulfidation as a result of improved structural stability upon Zr addition. Therefore, Pd-Cu-Zr alloys may offer new potential hydrogen purification membranes with improved chemical stability and hydrogen permeation compared to the binary fcc Pd-Cu alloys.

Enhancement of Interfacial Hydrogen Interactions with Nanoporous Gold-Containing Metallic Glass

“…Although Pd systems have been extensively studied in terms of gas–solid reactions, hydrogen permeation systems, or pressure-composition-isotherm measurements, − the diffusion and electron-transfer kinetics, as well as the stability during hydrogen sorption and evolution determine their practical applications. , In this respect, electrochemical impedance spectroscopy (EIS) provides remarkable insight into kinetic and diffusion-related parameters, including the influence of pores and composition, by frequency-dependent measurements. , Different parameters, i.e., charge-transfer resistance, solution and Warburg resistance, double-layer capacitance, inductance, and resistance and capacitance of interfaces and porous surfaces, are determined by means of fitting the experimental data with an equivalent circuit model (ECM). − In this work, we compare an optimized Pd–Au–Si glassy alloy based on our previous study and Pd nanocrystals sputtered on two different pore architectures and flat substrates. The hydrogen interactions with Pd in terms of porosity are assessed by EIS-ECM complemented by DC-type cyclic voltammetry (DC) and chronoamperometry (CA).…”

Nanoporous Zeolite-A Sheltered Pd-Hollow Fiber Catalytic Membrane Reactor for Propane Dehydrogenation

“…H 2 -permeable membranes are potential candidates to be used for selective removal of hydrogen from the reaction stream. − Palladium-based membranes are often suggested for a lighter alkane dehydrogenation process to simultaneously and selectively remove the in situ produced hydrogen from the reaction. − The combination of membrane separation and reaction in a single step helps in instantaneous removal of H 2 from the reaction product, thereby increasing the overall conversion. However, the Pd membrane suffers from lower stability in the presence of contaminating gases such as hydrocarbons. − Especially, in the presence of unsaturated hydrocarbons, such as propene, hydrogen permeation flux decreases drastically in the Pd membranes.…”

Universal Scaling and Design Rules of Hydrogen-Induced Optical Properties in Pd and Pd-Alloy Nanoparticles

“…% Au, increasing both sensor bandwidth and accuracy. In addition, the random alloy formation of Pd with Au improves the response time of a sensor based on these materials due to faster kinetics. ,,, …”