Adsorption of ammonia on vanadium antimony mixed oxides

HERNAN SEITZ; ESTEFANÍA GERMÁN; ALFREDO JUAN; BEATRIZ IRIGOYEN

APPLIED SURFACE SCIENCE

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2011 vol. 258 p. 3617 - 3623

0169-4332

We analyzed the adsorption of ammonia (NH3) on the VSbO4(1 1 0) catalyst surface using density functional theory (DFT) calculations. We followed the evolution of the chemical bonds between different atoms of the resulting NH3/VSbO4 system and the changes in the electronic structure of the catalyst. NH3 preferential adsorption geometries were analyzed through the crystal orbital overlap population (COOP) concept and the density of states (DOS) curves. The VSbO4(1 1 0) surface exhibits Lewis and Bronsted acid sites on which the ammonia molecule can interact. On the Lewis acid site, NH3 adsorption resulted in the interaction between the N and a surface V-isolated cation. On Bronsted acid site, N interacted with a surface H coming from the chemical dissociation of water. The COOP analysis indicate that NH3 interaction on the VSbO4(1 1 0) surface is weak. In addition, the DOS curves show more developed electronic interactions for NH3 adsorption on Lewis acid site than over Bronsted acid site.