Meerwein–Ponndorf–Verley–Oppenauer reaction of crotonaldehyde with ethanol over Zr-containing catalysts

• MPVO reaction of crotonaldehyde and ethanol has been studied over Zr-containing catalysts.
• The best catalyst performance in terms of activity and selectivity is observed over ZrBEA.
• The results point to the key role of Zr4+ Lewis acid sites.
• Isolated Zr atoms in zeolite crystalline structure are found to be the most efficient.

A series of Zr-containing catalysts including bulk ZrO2, ZrO2 supported on silica, titania and ceria, Zr-BEA zeolite and Zr-MCM-41 mesoporous material was prepared and characterized by X-ray diffraction, nitrogen adsorption-desorption, X-ray photoelectron spectroscopy, 29Si MAS NMR, TPD NH3, and FTIR of adsorbed CO. The catalytic materials were tested in the MPVO reaction of crotonaldehyde and ethanol in the temperature range of 473–573 K. The results showed that the activity of Zr-based catalysts in the MPVO reduction of crotonaldehyde correlates with the amount of Zr4+ Lewis acid sites in the catalysts. Tetrahedral Zr atom sites isolated within the crystalline structure of zeolite BEA were found to be the most efficient. The best catalyst performance in terms of selectivity was observed over ZrBEA: 72% selectivity to crotyl alcohol was achieved at crotonaldehyde conversion of 15%.

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