Quantum study of the active sites of the γ-alumina surface:: chemisorption and adsorption of water, hydrogen sulfide and carbon monoxide on aluminum and oxygen sites

In this work, we have performed quantum calculations, using cluster models, in order to study the reactivity of the aluminum and oxygen sites of the gamma-alumina surface. Water, hydrogen sulfide and carbon monoxide molecules are employed as the test molecules for our cluster models. It is found that the tricoordinated aluminum sites of the surface are the dissociative sites for the water and the hydrogen sulfide molecules. The tetracoordinated aluminum sites are the non-dissociative adsorption sites for the water molecule, whereas they are the dissociative sites for the hydrogen sulfide molecule. The pentacoordinated aluminum sites are the non-dissociative sites for the water and the hydrogen sulfide molecules. On the aluminum sites, carbon monoxide is preferentially adsorbed via its carbon atom. In contrast to the aluminum sites, the oxygen sites of the alumina surface are not adsorption sites for water, hydrogen sulfide and carbon monoxide molecules. (C) 2000 Elsevier Science B.V. All rights reserved.