Ammonia sorbent development for on-board H2 purification

• Developed NH3 sorbent material for on-board purification of hydrogen.
• Metal chloride impregnated super-activated carbon is thermally regenerable.
• NH3 adsorption isotherm equation includes MnCl2 ammoniate formation.

The application of chemical hydrides (e.g. ammonia borane) and amide-based hydrogen storage materials would benefit from an effective means to remove ammonia, which is an impurity that is detrimental to the performance of a PEM fuel cell. One option is to adsorb ammonia on a sorbent with high capacity that would also be regenerable. Such a sorbent was developed by impregnating super activated carbon with metal chlorides (MgCl2, ZnCl2, MnCl2). The sorbent was characterized through static and dynamic adsorption experiments. It was shown to have a good cyclic stability. The filter weight, volume and pressure drop appears reasonable for an onboard vehicle application when it would be replaced/regenerated every 1800 miles, similar to an oil change.