Using Mg‐Al Mixed Oxide and Reconstructed Hydrotalcite as Basic Catalysts for Aldol Condensation of Furfural and Cyclohexanone

Abstract

This study presents results on aldol condensation of furfural and cyclohexanone in presence of Mg‐Al hydrotalcite‐derived materials as solid basic catalysts at reaction temperatures from 25 to 90 °C and a cyclohexanone to furfural molar ratio of 1–10. Mg‐Al mixed oxide exhibited reasonable activity with furfural conversion of ca. 50 % after 180 min of the reaction at T=90 °C. The activity of reconstructed hydrotalcite was much higher with furfural conversion close to 100 % at short reaction times. In comparison with Mg‐Al mixed oxide, the initial reaction rate has increased 30–50 times. Under similar reaction conditions, cyclohexanone self‐condensation on HTC‐derived catalysts could not compete with aldol condensation because the former reaction was inhibited by produced water. The change in CH/F molar ratio influenced both furfural conversion and product selectivity; higher furfural content in the reaction mixture favored the second condensation step.

Solid Acids for the Reaction of Bioderived Alcohols into Ethers for Fuel Applications

“…One possibility is the aldol condensation with ketones over basic catalysts [51,52], which allows the obtainment of C9-C15 molecules that can eventually be further hydrogenated to form alkane chains. The oligomerization of furans via acid catalyzed condensation has also been reported as a carbon-upgrading process [53].…”

Structured hydroxyapatite composites as efficient solid base catalysts for condensation reactions

“…10,11 Liquid phase aldol condensation reactions are typically base-catalyzed, either by soluble bases or by solid materials such as alkali-metal containing zeolites, 12 alkaline-earth metal oxides, 13 and hydrotalcites. [14][15][16] Solid base use can indeed provide considerable advantages in terms of sustainability when it comes to waste generation, catalyst recovery, solvent use, etc. 17,18 Challenges in solid basecatalyzed conversions, on the other hand, include deactivation of the catalyst by poisoning, as well as catalyst instability issues, e.g.…”

The Influence of the Preparation Method on the Physico-Chemical Properties and Catalytic Activities of Ce-Modified LDH Structures Used as Catalysts in Condensation Reactions

“…The presence of another cyclohexanone molecule in the reaction medium can push the transformation to the di-condensation product or even further to dodecahydrotriphenylene or trihydroxyperhydrotriphenylene. Nowadays, although some catalytic materials have been highlighted for this transformation, including Mg-Al mixed oxide and reconstructed hydrotalcite [ 14 ], zirconia [ 15 ], MOF-encapsulating phosphotungstic acid [ 16 ], amberlyst 15 [ 13 , 17 ], silica chloride [ 18 ], keggin-type lanthanum phosphotungstate [ 19 ], and ion exchange resin [ 20 ], a lack of data involving the use of Ce-modified LDH catalysts can be noticed in the literature. Other than the self-condensation process, another interesting condensation reaction is the Claisen–Schmidt condensation, where compounds belonging to the flavonoid class, namely chalcone and flavone, are synthesized.…”