Ethanol can be used as a platform molecule for synthesizing valuable chemicals and fuel precursors. Direct synthesis of C5+ ketones, building blocks for lubricants and hydrocarbon fuels, from ethanol was achieved over a stable Pd‐promoted ZnO‐ZrO2 catalyst. The sequence of reaction steps involved in the C5+ ketone formation from ethanol was determined. The key reaction steps were found to be the in situ generation of the acetone intermediate and the cross‐aldol condensation between the reaction intermediates acetaldehyde and acetone. The formation of a Pd–Zn alloy in situ was identified to be the critical factor in maintaining high yield to the C5+ ketones and the stability of the catalyst. A yield of >70 % to C5+ ketones was achieved over a 0.1 % Pd‐ZnO‐ZrO2 mixed oxide catalyst, and the catalyst was demonstrated to be stable beyond 2000 hours on stream without any catalyst deactivation.

We investigate Pd x Cu y /SiO2 and Pd x Ag y /SiO2 catalysts in the context of oxygenate upgrading for biofuels. To this end, we measure the rates of decarbonylation and hydrogenation of butyraldehyde and the reactive intermediate for the industrially relevant Guerbet condensation and correlate the selectivity and reactivity with the properties of the catalysts via a range of characterization efforts. Data obtained from EXAFS and XANES show that the bulk of the catalyst metallic nanoparticles is enriched in Pd, while the surface is enriched in Cu and Ag. The data for Pd x Cu y /SiO2 show clear dominance of geometric (ensemble) effects on the selectivity. Conversely, the electronic (ligand) effects of alloying dominate over the reaction rate of the catalysts, as electron donation from Cu to Pd promotes Cu and increases the desired (de)­hydrogenation reactions. In contrast, in PdAg catalysts, the weaker electronic exchange, as indicated by Pd LIII XANES and theoretical calculations, is not sufficient to promote Ag, resulting in the monotonic loss of activity with the increasing Ag content and without selectivity improvement. We use the implications of these findings to provide valuable design principles for oxygenate catalysis and to discover a highly selective bifunctional catalyst system, comprising PdCu3/SiO2 and TiO2 for upgrading ethanol to longer-chain oxygenates.

Ethanol can be used as a platform molecule for synthesizing valuable chemicals and fuel precursors. Direct synthesis of C5+ ketones, building blocks for lubricants and hydrocarbon fuels, from ethanol was achieved over a stable Pd‐promoted ZnO‐ZrO2 catalyst. The sequence of reaction steps involved in the C5+ ketone formation from ethanol was determined. The key reaction steps were found to be the in situ generation of the acetone intermediate and the cross‐aldol condensation between the reaction intermediates acetaldehyde and acetone. The formation of a Pd–Zn alloy in situ was identified to be the critical factor in maintaining high yield to the C5+ ketones and the stability of the catalyst. A yield of >70 % to C5+ ketones was achieved over a 0.1 % Pd‐ZnO‐ZrO2 mixed oxide catalyst, and the catalyst was demonstrated to be stable beyond 2000 hours on stream without any catalyst deactivation.

Alloy formation between Pd and Zn enables a new catalytic pathway for the selective generation of high‐value compounds from renewable ethanol, as reported by K. K. Ramasamy and co‐workers in their Research Article on page 14550. The key reaction steps for the direct catalytic conversion of ethanol into C5+ ketones are the in situ generation of the acetone intermediate and the cross‐aldol condensation between the reaction intermediates acetaldehyde and acetone.

Die Bildung einer Pd/Zn‐Legierung  erschließt einen neuen katalytischen Reaktionsweg für die selektive Generierung von hochwertigen Verbindungen aus erneuerbarem Ethanol, wie K. K. Ramasamy et al. in ihrem Forschungsartikel auf S. 14658 berichten. Schlüsselschritte der direkten katalytischen Konversion von Ethanol zu C5+‐Ketonen sind die In‐situ‐Bildung des Aceton‐Intermediats und die gekreuzte Aldolkondensation zwischen den Reaktionsintermediaten Acetaldehyd und Aceton.