A small pilot reactor containing active MgTi–based hydrides at low operational temperatures

Abstract

This study was investigated to utilize innovatively oil-free diaphragm pump to forcibly desorb the hydrogen from the small pilot MgH2–TiH2 based hydride reactor below the theoretical temperature of 278 °C. Active MgH2-0.1TiH2 composites were prepared using ball milling. Their hydrogenation performances at 25–300 °C were measured under a constant H2 flow mode using a modified Sieverts apparatus. The dehydrogenation rates at 250–350 °C with or without diaphragm pump were investigated to examine whether the pilot reactors could be integrated with a proton exchange membrane fuel cell (PEMFC) for power generation. At a H2 flow rate of 25 ml min−1 g−1, the reactors exhibited excellent hydrogenation, achieving gravimetric hydrogen storage capacities of 2.9–5.2 wt% (excluding the weight of the reactors) at 25–300 °C after 22 min. All hydrided MgTi–based reactors could be dehydrogenated at 250 °C at an average rate of 5 ml min−1 g−1 under vacuum. This is the first demonstration of Mg-based reactors that were hydrogenated at 100 °C and dehydrogenated at 250 °C to power a small PEMFC, yielding a measured conversion efficiency of 18%.