Rapid annealing of sequentially plated Pd-Au composite membranes using high pressure hydrogen

Abstract

In this work, the time-consuming process of annealing Pd-Au alloy composite membranes, fabricated by sequential electroless plating, has been revisited. Composite Pd-Au/YSZ membranes approximately 5 µm thick with compositions ranging from 8 wt% to 10 wt% Au were fabricated by the bi-layer fabrication technique. Using these membranes, we investigated the effect of changing the pressure of the annealing gas (H 2) on annealing time at temperatures between 450 °C and 550 °C. X-ray diffraction (XRD) was used to study the progress of annealing, where it was observed that a ~10 wt% Au membrane could be annealed in 9 h at 550 °C and 3 MPa H 2 whereas it took 120 h to anneal a similar membrane at 550 °C and 0.1 MPa H 2. Another ~10 wt% Au membrane was annealed in less than 2 days at 450 °C and 3 MPa H 2. Complete annealing was confirmed using energy dispersive x-ray spectroscopy (EDS) with multiple spot scans throughout the thickness of the membrane indicating a uniform Au composition. Additionally, it was found that the apparent activation energy for hydrogen permeation (E act) could be used as an in situ parameter to judge the extent of annealing. In this technique, apparent E act decreases as the membrane anneals, reaching a minimum value which is characteristic of its Au composition. Additional annealing time does not further change the apparent E act for a membrane with a homogeneous Au distribution.

Synthesis, characterization and catalytic performance of core‐shell structure magnetic Fe3O4/P(GMA‐EGDMA)‐NH2/HPG‐COOH‐Pd catalyst

“…Comparing the data in Figure with the standard PDF card, the diffraction peaks at 30.21°, 35.04°, 43.04°, 53.41°, 57.02°, and 62.54° correspond to the inverse spinel Fe 3 O 4 face‐centered cubic lattice (220), (311), (400), (422), (511), (440) crystal planes . The diffraction peaks at 2θ = 40.10° correspond to the (111) crystal planes of Pd nanoparticles . The XRD characterization results showed that the cubic spinel‐structured Fe 3 O 4 nanocrystal was obtained and Pd 2+ was reduced to Pd.…”

Preparation of magnetic Fe3O4/P (GMA‐DVB)‐PEI/Pd highly efficient catalyst with core‐shell structure

“…Through contrasting the data in Figure with the standard PDF card, the diffraction peaks at 30.11°, 35.44°, 43.14°, 53.41°, 57.02°, and 62.54° correspond to (220), (311), (400), (422), (511), (440) crystal planes of the inverse spinel face‐centered cubic Fe 3 O 4 (JCPDS 85–1436) . From Figure (b), the diffraction peaks at 39.81° and 46.36° correspond to (111) and (200) crystal planes of Pd nanoparticles (JCPDS 46–1043) . On the basis of the results, Pd 2+ is reduced to Pd, and Fe 3 O 4 /P (GMA‐DVB)‐PEI/Pd microspheres catalyst is produced.…”

Review of Supported Pd-Based Membranes Preparation by Electroless Plating for Ultra-Pure Hydrogen Production

“…This drawback can be avoided by working at operating conditions above the mentioned critical point when membrane is exposed to hydrogen or modifying the Pd phase diagram [ 189 ]. The last option can be realized by alloying pure Pd with other metals, i.e., silver [ 52 , 106 , 190 , 191 , 192 ], copper [ 99 , 102 ], ruthenium [ 187 , 193 ] or gold [ 194 , 195 ]. It is demonstrated that Pd-based alloys with specific concentrations of these metals modify the metal-hydride phase diagram avoiding the mentioned embrittlement phenomena [ 28 ].…”

“…However, recent developments prefer faster processes in pressurized hydrogen atmosphere. In this case, it is proposed that dissolved hydrogen forms vacancies in the crystal lattice of palladium favouring the mobility of other alloy constituents and, consequently, reducing the time required to obtain the alloy [ 195 ]. As previously mentioned, layers prepared by co-deposition need softer thermal treatments (shorter times or lower temperatures) for annealing as compared with layers generated by sequential deposition (either consecutive or alternative) [ 95 , 202 ].…”