Relationship between Acid–Base Properties and the Activity of ZrO2‐Based Catalysts for the Cannizzaro Reaction of Pyruvaldehyde to Lactic Acid. Issue 14 (14th June 2017)

• Record Type: Journal Article
• Authors: Albuquerque, Elise M.; Borges, Luiz E. P.; Fraga, Marco A.; Sievers, Carsten
• Is Part Of: ChemCatChem. Volume 9:Issue 14(2017)
• Page Start: 2675
• Page End: 2683
• Publication Date: 2017-06-14
• Subjects: acidity -- aldehydes -- basicity -- Cannizzaro reaction -- zirconium; Catalysis -- Periodicals; 541.39505
• DOI: 10.1002/cctc.201700305
• Languages: English
• ISSNs: 1867-3880

Abstract

Abstract: The Cannizzaro reaction of pyruvaldehyde to lactic acid is investigated in a flow reactor with ZrO2 catalysts with different structures and acid–base properties. The results show that a difference in the crystalline structures of two ZrO2 polymorphs strongly affects the conversion of pyruvaldehyde. The monoclinic phase of zirconia is the most active for this reaction. A good correlation is observed between the reaction rate and the concentration of Lewis acid sites of sufficient strength, which shows that these sites play a major role in the reaction. A reaction mechanism is proposed involving coordinatively unsaturated Zr 4+ cations as sites for activating pyruvaldehyde molecules, whereas Zr 4+ −O 2− pairs generate terminal OH groups through water dissociation. Abstract : It's all about the acid : Lewis acid sites and mobile surface hydroxy groups play significant roles in the Cannizzaro reaction of pyruvaldehyde over ZrO2 ‐based catalysts. Differences in the crystalline structures of two ZrO2 polymorphs strongly affects the conversion of pyruvaldehyde. The monoclinic phase of zirconia is the most active for this reaction.