Platinum Island-on-Copper–Nickel Alloy Nanoparticle/Carbon Trimetallic Nanocatalyst for Selective Hydrogenation of Cinnamaldehyde

Abstract

Two series of catalysts, i.e., [Ni/C, Cu/C and CuNi/C] and [Pt–Ni/C, Pt–Cu/C and Pt–CuNi/C] were prepared by liquid phase chemical reduction and galvanic replacement, respectively. Pt/C was synthesized via an impregnation method. The nanostructures of these catalysts were tuned by being reduced in N2 + H2. Their nanostructures were characterized by TG, XPS, XRD, TEM, HRTEM and STEM–EDS elemental analysis techniques. The catalysts, which had unique nanostructures resulted from the loading of platinum islands on the transition metal related nanoparticles (i.e., Pt–Ni/C with Pt-on-Ni/Ni(OH)2, Pt–Cu/C-reduced with Pt-on-Cu/CuO, Pt–CuNi/C-reduced with Pt-on-CuNi alloy), exhibited much more excellent catalytic performance (conversion of cinnamaldehyde: 100.0%, selectivity to cinnamyl alcohol: 62.9%, 64.6% and 72.6%, respectively) than the catalysts with platinum–transition metal alloy structure (e.g. Pt–Ni/C-reduced with PtNi alloy) and transition metal/carbon for the selective hydrogenation of cinnamaldehyde (80 °C, 5.0 MPa H2, 1 h). The Pt–CuNi/C-reduced catalyst also showed superior stability in cinnamaldehyde hydrogenation. The outstanding performance of Pt–Ni/C, Pt–Cu/C-reduced and Pt–CuNi/C-reduced catalysts for cinnamaldehyde hydrogenation was attributed to the synergistic effect and interaction of platinum and non-noble metal related nanoparticles.