Investigation of hydrogen absorption kinetics on intermetallic compounds Hf2Ni, Hf2Co and Hf2Fe

• Published in: Hemijska industrija 2009-01, Vol.63 (3), p.159-162
• Main Authors: Kumric, Sandra, Stojic, Dragica, Cekic, Bozidar
• Format: Article
• Language: English
• Subjects: activation energy; hydriding capacity; hydriding isotherm; intermetallics; rate constant
• ISSN: 0367-598X; 2217-7426
• DOI: 10.2298/HEMIND0903159K

Polycrystalline intermetallics Hf2Ni, Hf2Co and Hf2Fe are investigated as the hydrogen absorbers in the temperature range 348 to 823 K, under the constant hydrogen pressure of 1 bar. The absorption process was carried out in typical volumetric apparatus and H/M mole ratios together with rate constants and activation energies for hydrogen absorption reaction were determined. Achieved hydrogen absorption capacities at 573 K are: 0.60, 0.90 and 1.48 and rate constants at 573 K are: 0.38?10-3, 0.55?10-3 and 4.72?10-3 s-1 for Hf2Ni, Hf2Co and Hf2Fe respectively. Determined activation energies are: for Hf2Ni, 38.44 kJ/mol, for Hf2Co, 19.62 kJ/mol and 2.74 kJ/mol for Hf2Fe. From the obtained experimental results, it was concluded that Hf2Fe has the best hydrogen absorption ability among the examined intermetallics. U ovom radu ispitivana je kinetika hidriranja polikristalnih materijala Hf2Ni, Hf2Co i Hf2Fe u temperaturskom opsegu 348-823 K, pri pritisku vodonika od 1 bar. Proces apsorpcije vodonika izveden je u specijalno konstruisanoj volumetrijskoj aparaturi. Odredjeni su kapaciteti apsorpcije, konstante brzina reakcija i energije aktivacije za reakciju apsorpcije vodonika. Dobijene energije aktivacije su: za Hf2Ni 38,44 kJ/mol, za Hf2Co 19,62 kJ/mol i za Hf2Fe 2,74 kJ/mol. Dobijeni kineticki parametri pokazuju da je Hf2Fe najbolji apsorber vodonika medju ispitivanim intermetalicima.