Hydrogen desorption from nanostructured magnesium hydride composites

The influence of 3d transition metal addition (Fe, Co and Ni) on the desorption properties of magnesium hydride were studied. The ball milling of MgH2-3d metal blends was performed under Ar. Microstructural and morphological characterization were performed by XRD and SEM analysis, while the hydrogen desorption properties were investigated by DSC. The results show a strong correlation between the morphology and thermal stability of the composites. The complex desorption behavior (the existence of more than one desorption peak) was correlated with the dispersion of the metal additive particles that appear to play the main role in the desorption. The desorption temperature can be reduced by more than 100 degrees if Fe is added as additive. The activation energy for H2 desorption from the MgH2-Fe composite is 120 kJ/mol, implying that diffusion controls the dehydration process. Nanostrukturni kompoziti MgH2-Me (Me = Fe, Co i Ni) sintetisani su mehanickim mlevenjem u mlinu sa kuglama u atmosferi argona. Ispitivan je kataliticki uticaj prirode aditiva (Me) na brzinu desorpcije vodonika. Mikrostruktura i morfologija kompozita su ispitivani rendgenostrukturnom i SEM analizom, dok je desorpcija vodonika pracena diferencijalnom skenirajucom kalorimetrijom. Primeceno je da najbolje osobine za cuvanje vodonika ima kompozit MgH2-Fe kod koga je temperatura desorpcije snizena za 120 stepeni u odnosu na referentni MgH2 Izracunate aktivacione energije za disocijaciju brojcano odgovaraju difuzijom kontrolisanom procesu dehidriranja.