High-Temperature Hydrogen Permeability Tests of Ta Tubes

Area of Science:

• Materials Science
• Chemical Engineering
• Physical Chemistry

Background:

• Refractory metals are explored as alternatives to palladium for high-temperature hydrogen separation.
• Membrane reactors for hydrogen production require understanding hydrogen permeability through materials like tantalum (Ta).

Purpose of the Study:

• To investigate hydrogen permeability through tantalum (Ta) membranes at temperatures up to 1573 K.
• To determine the effect of high-temperature exposure and surface oxidation on Ta hydrogen permeability.

Main Methods:

• Experimental setup designed for testing Ta tubes in the 673-1573 K range.
• Controlled atmospheres and ultra-pure gases used to minimize contamination.
• Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM-EDS) for surface analysis.

Main Results:

• Hydrogen permeability data for Ta was obtained between 673-1573 K.
• Surface oxide layer formation was observed on Ta above 1473 K.
• Activation energy for permeation increased significantly from 2679.8 K (673-1273 K) to 30,691 K (1473-1573 K) due to oxidation.

Conclusions:

• High-temperature oxidation of Ta membranes drastically increases the energy barrier for hydrogen permeation.
• Tantalum's suitability for high-temperature hydrogen separation is limited by surface oxidation effects.
• Further research needed to mitigate oxidation for effective Ta-based membrane reactors.