Isopropanol Dehydration on Amorphous Silica–Alumina: Synergy of Brønsted and Lewis Acidities at Pseudo-Bridging Silanols

Kim Larmier (1, 2) , Céline Chizallet (1) , Sylvie Maury (1) , Nicolas Cadran (1) , Johnny Abboud (2) , Anne-Félicie Lamic-Humblot (2) , Eric Marceau (2) , Hélène Lauron-Pernot (2)

1 IFPEN - IFP Energies nouvelles
2 LRS - Laboratoire de Réactivité de Surface

The mechanism of isopropanol dehydration on amorphous silica–alumina (ASA) was unraveled by a combination of experimental kinetic measurements and periodic density functional theory (DFT) calculations. We show that pseudo-bridging silanols (PBS-Al) are the most likely active sites owing to the synergy between the Brønsted and Lewis acidic properties of these sites, which facilitates the activation of alcohol hydroxy groups as leaving groups. Isopropanol dehydration was used to specifically investigate these PBS-Al sites, whose density was estimated to be about 10@1 sitenm@2 on the silica-doped alumina surface under investigation, by combining information from experiments and theoretical calculations.

Domaines: Chimie

Kim Larmier, Céline Chizallet, Sylvie Maury, Nicolas Cadran, Johnny Abboud, et al.. Isopropanol Dehydration on Amorphous Silica–Alumina: Synergy of Brønsted and Lewis Acidities at Pseudo-Bridging Silanols. Angewandte Chemie International Edition, 2017, 56, pp.230-234. ⟨10.1002/anie.201609494⟩. ⟨hal-01518477⟩