Katalitički uticaj Co na kinetiku dehidriranja MgH2

MgH2 se može koristiti za skladištenje vodonika, ali je kinetika procesa hidriranje/dehidriranje na sobnoj temperaturi spora. Mehaničko legiranje sa 3d prelaznim metalima predstavlja najčešće korišćen metod ubrzanja reakcije dehidriranja. Mehaničkim mlevenjem su sintetisani kompoziti MgH2-Co. Određeni su parametri reakcije dehidriranja (n i k) i energija aktivacije EA izotermalnom JMA metodom. Dobijene vrednosti energije aktivacije za dehidriranje su oko 130kJ/mol, vrednosti konstanti brzina reakcije dehidriranja reda veličine 10-4, dok se vrednosti Avramijevog parametra nalaze u graničnoj oblasti (n ≈ 1). Dobijeni rezultati ukazuju da proces difuzije i proces nukleacije i rasta nove faze istovremeno kontrolišu proces dehidriranja kompozita MgH2-Co

Calculation of structural parameters with help of the Gaussian program package

LXVI Savetovanje Srpskog hemijskog društva : program i kratki izvodi radova; Oktobar 21, 2008, Beogra

Original scientific paper Are the program packages for molecular structure calculations really black boxes?

Abstract: In this communication it is shown that the widely held opinion that compact program packages for quantum–mechanical calculations of molecular structure can safely be used as black boxes is completely wrong. In order to illustrate this, the results of computations of equilibrium bond lengths, vibrational frequencies and dissociation energies for all homonuclear diatomic molecules involving the atoms from the first two rows of the Periodic Table, performed using the Gaussian program package are presented. It is demonstrated that the sensible use of the program requires a solid knowledge of quantum chemistry

Development of SEM Metallography for the Study of the Mg-MgH2 Phase Transformation

The study of sorption reactions of metal hydrides is the subject of numerous researches in connection with the development of a safe technology for hydrogen storage, and MgH2, in particular, is one of the most promising materials. Several efforts have been already carried out in order to understand the kinetic mechanisms involved in the MgH2 decomposition which is at the basis of H2 release. However, the role of additives and induced structural defects on the sorption cycles is not clear yet. With the purpose of supporting the reaction analysis we have developed an experimental protocol for the metallographic examination at high spatial resolution of partially desorbed MgH2 powders. In particular, this procedure allows cross-sectional analysis of powders embedded into conductive matrix, while the observation method produces a different contrast among metallic Mg, MgH2 and additive particles made of heavier materials.Materials and Technology for Hydrogen Storage : November 26-30, 2007