Vacancy diffusion in palladium hydrides.

The self-diffusion coefficients of palladium in PdHx (x = 0, 0.25, 0.5, 0.

Flux-Reducing Tendency of Pd-Based Membranes Employed in Butane Dehydrogenation Processes.

We report on the effect of butane and butylene on hydrogen permeation through thin state-of-the-art Pd-Ag alloy membranes. A wide range of operating conditions, such as temperature (200-450 °C) and H/butylene (or butane) ratio (0.5-3), on the flux-reducing tendency were investigated.

Factors Limiting the Apparent Hydrogen Flux in Asymmetric Tubular Cercer Membranes Based on LaWMoO and LaSrCrO.

Asymmetric tubular ceramic-ceramic (cercer) membranes based on LaWMoO-LaSrCrO were fabricated by a two-step firing method making use of water-based extrusion and dip-coating. The performance of the membranes was characterized by measuring the hydrogen permeation flux and water splitting with dry and wet sweep gases, respectively. To explore the limiting factors for hydrogen and oxygen transport in the asymmetric membrane architecture, the effect of different gas flows and switching the feed and sweep sides of the membrane on the apparent hydrogen permeability was investigated.

New Insight to the Effects of Heat Treatment in Air on the Permeation Properties of Thin Pd77%Ag23% Membranes.

Sputtered Pd77%Ag23% membranes of thickness 2.2⁻8.5 µm were subjected to a three-step heat treatment in air (HTA) to investigate the relation between thickness and the reported beneficial effects of HTA on hydrogen transport.

Grain Boundary Segregation in Pd-Cu-Ag Alloys for High Permeability Hydrogen Separation Membranes.

Dense metal membranes that are based on palladium (Pd) are promising for hydrogen separation and production due to their high selectivity and permeability. Optimization of alloy composition has normally focused on bulk properties, but there is growing evidence that grain boundaries (GBs) play a crucial role in the overall performance of membranes. The present study provides parameters and analyses of GBs in the ternary Pd-Ag-Cu system, based on first-principles electronic structure calculations.

Influence of Ce polarons on grain boundary space-charge in proton conducting Y-doped BaCeO.

Defect segregation and space-charge formation were investigated for a (0 2 1)[1 0 0] symmetric tilt grain boundary in Y-doped BaCeO3. Density functional theory calculations according to the PBE+U formalism were used to calculate segregation energies for protons, oxygen vacancies and Y-acceptor dopants from the bulk to the grain boundary core. Defect concentration and potential profiles across the grain boundary were obtained from thermodynamic space-charge models.

Dual phase high-temperature membranes for CO separation - performance assessment in post- and pre-combustion processes.

Dual phase membranes are highly CO-selective membranes with an operating temperature above 400 °C. The focus of this work is to quantify the potential of dual phase membranes in pre- and post-combustion CO capture processes. The process evaluations show that the dual phase membranes integrated with an NGCC power plant for CO capture are not competitive with the MEA process for post-combustion capture.

Investigation of La1-xSrxCrO3-∂ (x ~ 0.1) as Membrane for Hydrogen Production.

Various inorganic membranes have demonstrated good capability to separate hydrogen from other gases at elevated temperatures. Hydrogen-permeable, dense, mixed proton-electron conducting ceramic oxides offer superior selectivity and thermal stability, but chemically robust candidates with higher ambipolar protonic and electronic conductivity are needed. In this work, we present for the first time the results of various investigations of La1-xSrxCrO3-∂ membranes for hydrogen production.