Application of TiC in Vanadium-Based Hydrogen Membranes

Abstract

Transition metal carbide coated vanadium membranes for hydrogen permeation have the unique ability to operate at both high temperatures and pressures. Titanium carbide deposited by magnetron sputtering produced dense, nanocrystalline films preferentially oriented in the ( 111) plane. When applied on vanadium foils, TiC was a highly active catalytic coating enabling permeation of ultrapure H 2 with fluxes up to 0.71 mol m −2 s −1 at 10 bar and 923 K. The TiC thickness controlled H 2 transport in the composite membranes. Thicker TiC films and low temperature operation yielded n-values >1, which were likely resultant of adsorption effects and surface diffusion through the carbide layer. Competitive adsorption in mixed gas environments inhibited H 2 flux through TiC/V membranes, but addition of thin (50−100 nm) Pd films to the TiC surface instilled chemical resistance and improved permeation at 773 K. Permeation attenuated for membranes with TiC thicknesses <20 nm but 23 nm thick coatings demonstrated stable flux for 30 h.

Recent Developments in Compact Membrane Reactors with Hydrogen Separation

“…Early attempts to overcome surface poisoning of group V metal membranes were made in 1967, when Makrides, Wright, and Jewett patented membranes made from group V metals coated with thin layers of palladium on both sides [20]. Publications from the last years, on group V metal-based hydrogen membranes with palladium-based or transition metal carbide protection layers, show further development but also outline tremendous challenges, among which, attenuation of hydrogen flux over time in consequence of, for instance, interdiffusion of membrane and top-layer materials at elevated temperatures [18,19,21,22].…”