Carbon nanotubes supported Pt-Ni catalysts and their properties for the liquid phase hydrogenation of cinnamaldehyde to hydrocinnamaldehyde

The Pt-Ni catalysts supported on CNTs have been prepared by wet impregnation and the selective hydrogenation of cinnamaldehyde (CMA) to the corresponding hydrocinnamaldehyde (HCMA) over the catalysts has been studied in ethanol at different reaction conditions. The results show that Pt-0.34 wt% Ni/CNTs catalyst exhibits the highest activity and selectivity at a reaction temperature of 70 °C under a pressure of around 2.0 MPa, and 98.6% for the conversion of CMA and 88.2% for the selectivity of CMA to HCMA, respectively. The selective hydrogenation for the CC bond in CMA would be improved as increasing the reaction temperature, and the hydrogenation for the CO bond in CMA is enhanced as increasing the H₂ pressure. In addition, these catalysts have also been characterized using TEM-EDS, XPS, H₂-TPR and H₂-TPD techniques. The results show that Pt particles are dispersed more homogeneously on the outer surface of the nanotubes, while the strong interaction between Pt and Ni would improve the increasing of activated hydrogen number because of the hydrogen spillover from reduced Pt⁰ onto CNTs and increase the catalytic activity and selectivity of CMA to HCMA.