Discovering the role of substrate in aldehyde hydrogenation

• Published in: Journal of catalysis Vol. 399; pp. 162 - 169
• Main Authors: Cattaneo, Stefano, Capelli, Sofia, Stucchi, Marta, Bossola, Filippo, Dal Santo, Vladimiro, Araujo-Lopez, Eduard, Sharapa, Dmitry I., Studt, Felix, Villa, Alberto, Chieregato, Alessandro, Vandegehuchte, Bart D., Prati, Laura
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 01.07.2021
• Subjects: Adsorption; Aliphatic aldehyde; Aromatic aldehyde; Electron conjugation; Hydrodeoxygenation; Hydrogenation; Palladium catalyst; Electron conjugation; Hydrodeoxygenation; Palladium catalyst; Aromatic aldehyde; Adsorption; Aliphatic aldehyde; Hydrogenation
• ISSN: 0021-9517; 1090-2694
• DOI: 10.1016/j.jcat.2021.05.012

[Display omitted] •The importance of the side chains of aldehydes in determining the reactivity of carbonyl groups was demonstrated.•Mode and strength adsorption are affected by the structure of the substrate, but these aspects are not the decisive factors.•Electronic activation via strong π-electron conjugation is key in the conversion of aldehydes to alcohols and hydrocarbons.•The study increases our knowledge of the mechanisms that govern heterogeneous catalysis. In this manuscript, we investigated in detail one of the critical parameters that govern the reactivity of the carbonylic group toward hydrogenation and hydrodeoxygenation: the effect of the side chains of aldehydes. We observed that the presence of a π-electron conjugation on the side chains strongly affects the conversion of aldehydes to alcohols and hydrocarbons under the reaction conditions studied. In particular, the presence of a strong π-electron conjugation, such as the aromatic ring, enables the hydrogenation and further hydrodeoxygenation of the carbonylic group, while, on the other hand, molecules with no or weak π-electron conjugation (such as alkyl chains or single conjugated CC double bonds) remained inactive. These results were supported by adsorption analyses as well as theoretical models, which showed that differences in adsorption mode and strength between two model substrates (benzaldehyde and octanal) were not the decisive factors in the conversion of the carbonyl group.