Effect of the acid–base properties of the support on the performance of Pt catalysts in the partial hydrogenation of citral
•Acid or basic nature of catalyst induces selectivity in citral hydrogenation.•Acidity tendency was: Pt/SiO2–ZrO2 > Pt/SiO2–TiO2 > Pt/SiO2 > Pt/MgAl-c.•Nerol–geraniol products were promoted in acid materials Pt/SiO2–(TiO2 and ZrO2)•In basic catalyst Pt/(MgAl-c and MgAl-r) citronellal was the main product.•High catalytic activity was verified over small Pt particles (2 nm) in Pt/MgAl-c.
In this work, the effect that mesoporous solid materials, with different acid–base properties (Pt-1 wt%/acid or base) have over the product distribution during the partial hydrogenation of citral was evaluated. It was found that basic materials were the most active catalysts reaching a 100% citral conversion after 1 h of reaction. Regarding selectivity, in basic materials (Pt/MgAl-c and Pt/MgAl-r) citronellal was the main product, while nerol and geraniol were produced in acid solids (Pt/SiO2; Pt/SiO2–TiO2 and Pt/SiO2–ZrO2). The formation of unsaturated alcohols is related to the strength and density of the acid sites of the catalyst and in this sense the Pt/SiO2–ZrO2 gave a yield of 80%. The acidity trend is: Pt/SiO2–ZrO2 > Pt/SiO2–TiO2 > Pt/SiO2 > Pt/MgAl-c.
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Journal: Catalysis Today - Volume 213, 15 September 2013, Pages 101–108