Carbon nanotubes supported palladium catalysts for selective hydrogenation of cinnamaldehyde under atmospheric pressure

Carbon nanotubes supported Pd catalysts have been prepared by an impregnation method with aqueous solution containing a Pd(II) salt. The selective hydrogenation of cinnamaldehyde with the catalysts is studied in ethanol at 30 degrees C under atmospheric pressure. A comparison has been made with activated carbon and graphite supported Pd catalysts. The results show that all the Pd/CNTs catalysts prepared with different Pd precursors exhibit good catalytic properties. The Pd/CNTs(a) catalyst prepared with Pd(NH3)(4)Cl-2 as Pd precursor shows remarkably high selectivity (90.8%) for the conversion of cinnamaldehyde (92.0%) with 18.1 mmol H-2 g(-1) min(-1) hydrogenation rate. The influence of the solvent polarity and promoter has been investigated. The results demonstrate that highly polar solvent is advantageous for catalytic activity of Pd/CNTs(a) catalyst, while traces of weak base is advantageous for selective hydrogenation of C = C double bond.