Liquid phase selective hydrogenation of cinnamaldehyde over copper supported catalysts

The selective hydrogenation of cinnamaldehyde is carried out in a batch reactor, at 100 °C and 1 MPa of H2 using isopropyl alcohol as the solvent, over a series of copper supported catalysts: Cu/Al2O3, Cu/SiO2 Cu/MCM-48, Cu/CeO2 and Cu/α-Fe2O3. The selectivity of the samples is compared with that corresponding to Pti/SiO2. Reduced Cu/Al2O3 and Cu/SiO2 showed lower selectivity to the cinnamyl alcohol (16–22%) than Pt/SiO2 (35%), at 15% of conversion. Following a calcination at 300 °C both, activity and selectivity of copper catalysts were increased. The calcined surface would hydrogenate CO bond by hydrogen transfer from the solvent. TPR, XRD and FTIR of adsorbed CO showed that Cu (I) species are stabilized on the mesoporous structure of MCM-48. This particular feature renders Cu/MCM-48 a selective catalyst, reaching high selectivity values (51%, at 15% of conversion). Cu/CeO2 and Cu/α-Fe2O3 showed higher selectivity than Pt based catalyst due to a promotion of the catalytic properties of copper by reduced support species.

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► In this study a series of Cu catalysts are evaluated for the selective hydrogenation of cinnamaldehyde.
► Cu1+ species are stabilized on MCM-48, turning Cu/MCM-48 a selective catalysts.
► Hydrogen transfer from isopropanol is achieved under certain experimental conditions.
► Some copper catalysts are more selective than noble based ones.