resumo
This study highlights that Fe additives offer better catalytic properties than carbon, Fe-C (iron carbide/carbon composites), and Fe-Mg (Mg2FeH6) additives for the low-temperature dehydrogenation of magnesium hydride. The in situ X-ray diffraction measurements prove the formation of a Mg2FeH6 phase in iron additive loaded MgH2. Nonetheless, differential scanning calorimetry data suggest that this Mg2FeH6 phase does not have any influence on dehydrogenation properties of MgH2. On the other hand, the composite system Mg2FeH6/MgH2 shows significantly improved dehydrogenation properties even in absence of further additives. It is suggested that the improved system performance of Fe loaded MgH2 is attributed to restrictions on crystal growth of MgH2 and the catalytic behavior of Fe nanoparticles, rather than any intrinsic catalytic properties offered by the formed mixed metal phase Mg2FeH6.
palavras-chave
HYDROGEN STORAGE; METAL HYDRIDES; SORPTION; NI; TI; NANOPARTICLES; DESORPTION; MECHANISM; NB; DIFFUSION
categoria
Chemistry; Physics
autores
Pukazhselvan, D; Nasani, N; Yang, T; Bdikin, I; Kovalevsky, AV; Fagg, DP
nossos autores
agradecimentos
D.P. acknowledges financial support from Fundacao para a Ciencia e a Tecnologia (FCT, Portugal) through grant number SFRH/BPD/88756/2012. N.N. acknowledges the financial support from the FCT grant PTDC/CTM-ENE/6319/2014. D.P.F. acknowledges FCT, Fundo Europeu de Desenvolvimento Regional (FEDER), and Programa Operacional Factores de Competitividade (COMPETE) for the grants EXPL/EMS-ENE/1497/2013, PTDC/CTM-ENE/6319/2014, and IF/01344/2014/CP1222/CT0001. A.V.K. acknowledges support from the project CICECO-Aveiro Institute of Materials (ref. UID/CTM/50011/2013).