IFISUR   23398
INSTITUTO DE FISICA DEL SUR
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Study of the hydrogen/iron- nickel catalyst interactions
Autor/es:
S. SIMONETTI; F. REY SARAVIA; G. CANTO
Reunión:
Conferencia; IX International Conference Mechanisms of Catalytic Reactions; 2012
Resumen:
The world's oil reserves are being rapidly depleted; therefore the supply of hydrogen remains virtually unlimited and produces no air pollutants. Hydrogen can be produced from several sources, reducing our dependence on petroleum. Hydrogen can be obtained from renewable sources through thermal or catalytic processes. Iron promoted nickel based catalyst has been developed for high yield hydrogen generation [1]. Investigations have reported that binary Fe- Ni decreased the decomposition temperatures and yielded 70-90% hydrogen in the temperature range of 650 to 800°C [2]. We have analyzed at theoretical level, the adsorption of H on a FeNi(111) catalyst by tight binding calculations [3]. Different sites on the surface were selected in order to establish the preferential H adsorption location and the optimum H-surface distance. The two most stable sites for H on FeNi(111) are those where H bonds on top Fe at 1.50 Å to the surface and the H bonds on the Fe-Fe bridge site at 0.70 Å above the surface. We found that the minimum energy site corresponds to the H bonding on top Fe. Fe-H bond is formed on the FeNi surface and the interaction is mainly due to the overlaps between the H s orbital with the pz, s, dz2 and py Fe orbitals. As a consequence, it is observed a Fe-Fe bond weakening of 12 %. On the other hand, when the H is located on the Fe-Fe bridge site, the Fe-H interactions weaken the Fe-Fe nearest bonds to about 33% with mainly participation of pz, py, s and dyz Fe orbitals. In general, after H adsorption, the Fe-Ni and Ni-Ni bonds are slightly affected. The Ni-H interaction is not evidence on the FeNi(111) surface.