C₆₀とFeを添加したMgの水素吸蔵・放出特性

抄録

This study investigated the hydrogen absorption-desorption properties of Mg-based composites containing C₆₀ and Fe, i.e., Mg-C₆₀, Mg-Fe and Mg-C₆₀-Fe that were prepared with ball milling. We also added stearic acid (SA) as a milling aid to Mg-Fe and Mg-C₆₀-Fe as Mg-Fe + SA and Mg-C₆₀-Fe + SA, respectively. The X-ray diffraction profiles showed that MgH₂ was observed in Mg-Fe, Mg-Fe + SA , Mg-C₆₀-Fe and Mg-C₆₀-Fe + SA hydrogenated at 280℃ and 0.99 MPa, and MgO was also observed in the Mg-Fe + SA and Mg-C₆₀-Fe + SA only that were milled with stearic acid. Mg-Fe, MgFe + SA, Mg-C₆₀-Fe and Mg-C₆₀-Fe + SA were absorbed hydrogen up to 2.57 wt.%, 2.93 wt.%, 3.10 wt.% and 2.42 wt.%, respectively at 280℃ in pressure-composition-temperature (PCT) measurements and their hydrogen release temperatures were in range of 297 - 378°C according to the different scanning calorimetry profiles. The PCT curves also showed that Mg-Fe and Mg-C₆₀-Fe released hydrogen around 0.1 MPa, while Mg-Fe + SA and Mg-C₆₀-Fe + SA did not release below 0.1 MPa. These results suggest that Fe has an excellent catalytic effect in the hydrogenation, and stearic acid oxidizes Mg and decreases their hydrogen storage capacities. By morphology observations, C₆₀ inhibited agglomerations of particles without oxidizing Mg, and formed fine particles on Mg surface, which were thought to enhance its hydrogen storage capacity.