Microstructure Analysis of the Intermetallic Diffusion-Induced Alloy Phases in Composite Pd/Ag/Porous Stainless Steel Membranes

Abstract

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. The complete miscibility of the Pd and Fe binary solid solutions was verified by the X-ray phase analysis. The Fe segregation into the Pd matrix was as high as 59 wt % upon annealing at 800 °C for 20 h in H 2 . It was further shown that the solid solutions of Fe and Ag were immiscible for the temperature range investigated. In the case of the ternary phase analysis, it was found that both the Pd/Fe and Pd/Ag alloy formations took place on the support surface, in which both alloy compositions became richer in Pd with decreasing annealing temperature.

Impact of support mass flow resistance on low-temperature H2 permeation characteristics of a Pd95Ag5/Al2O3 composite membrane

“…2 shows the XRD pattern of the membrane indicating a single face-centered cubic (fcc) phase and the formation of a homogeneous alloy. It has been previously suggested that the lattice constant of PdAg membranes varies with alloy composition according to Vegard's law [3,11]. However, no practical relationship between lattice constant and alloy stoichiometry was given there.…”

Dry reforming of methane in membrane reactors using Pd and Pd–Ag composite membranes on a NaA zeolite modified porous stainless steel support

“…The diffractogram obtained after the vacuum-assisted dip coating and short Pd depositions (Fig. 10b) shows the reflection peaks of both the ␥-phase (austenite) and pure palladium (at 39.6 • , 46.2 • , 67.6 • , 81.7 • and 86 • ), suggesting that the metallic deposition is <1 m thick [28].…”

Ultra-microporous membrane separation using toluene to simulate tar-containing gases

“…To address this problem, several groups have developed metal/alloys [15][16][17][18] or microporous ceramic membranes based on silica [19][20][21][22] and zeolites [23][24][25] for H 2 separation at high temperatures. In addition, membrane reactor configurations have been investigated, where WGSR catalysts and membranes are integrated into a single process unit for H 2 separation and the subsequent WGSR shifting, overcoming equilibrium limitations at the same time [25][26][27][28][29].…”