Effects of elevated temperatures and contaminated hydrogen gas mixtures on novel ultrathin palladium composite membranes

• Published in: International journal of hydrogen energy Vol. 42; no. 49; pp. 29310 - 29319
• Main Authors: Dunbar, Zachary W., Lee, Ivan C.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 07.12.2017
• Subjects: Fuel processing; Fuel reforming; Hydrogen; Palladium membrane; Purification; Separation; Separation; Purification; Hydrogen; Palladium membrane; Fuel processing; Fuel reforming
• ISSN: 0360-3199; 1879-3487
• DOI: 10.1016/j.ijhydene.2017.10.032

Transmembrane hydrogen flux of a novel 1 μm palladium membrane, supported by a nickel microstructured support grid, is characterized when exposed to carbon dioxide, carbon monoxide and water vapor over a range of temperature from 235° to 320 °C. At all temperatures, the palladium membrane is found to be primarily hydrogen transport rate limited due to surface reactions, not atomic hydrogen solution-diffusion though the bulk palladium membrane. Hydrogen flux decreases rapidly as contaminate gas concentration increases, before reaching a temperature dependent steady state, due to nearly complete surface coverage of the palladium by adsorbed contaminate. Carbon monoxide and carbon dioxide have the largest impact, while water vapor has a lesser impact. The likely source of deactivation is the blocking of surface active sites by adsorbed contaminate molecules. Independent of contaminate gas effects, this study reveals a permanent hydrogen flux decrease due to diffusion of nickel from the microstructured support grid into the palladium membrane at temperatures above 360 °C. •Impact of CO, CO2 and water vapor contaminates on H2 flux through membrane.•CO and CO2 have large negative impact on flux at all temperatures tested.•Water vapor's negative impact on flux correlates with increasing temperatures.•Diffusion of palladium into support metal limits upper operating temperature.