Plant-Mediated Synthesis of Zinc Oxide Supported Nickel-Palladium Alloy Catalyst for the Selective Hydrogenation of 1,3-Butadiene

We report the green synthesis of ZnO-supported Ni-Pd alloy nanoparticles for the gas-phase selective hydrogenation of 1,3-butadiene. The supported catalysts were synthesized through a simple bioreduction route using Cinnamomum Camphora leaf extract. We used XRD, SEM, TEM, and energy-dispersive Xray spectroscopy to characterize and verify the nature of the catalysts. The results showed that the size of the Ni-Pd alloy particles was (3.2 +/- 0.7), (3.4 +/- 0.3), and (3.8 +/- 0.6) nm for Ni1Pd1, Ni1Pd3, and Ni3Pd1 respectively. FTIR spectroscopy revealed that the presence of stretching vibrations from C-H, -C=C-, O-H, and -C-O-O groups that remained on the surface and act as stabilizers. The influence of some reaction variables, such as the type of S-Pd (S=Au, Ag, Ni) bimetallic catalyst, the type of metal oxide support, and the reaction temperature, on the hydrogenation activity and selectivity towards total butene (trans-2-butene, 1-butene, and cis-2-butene) is investigated. The bioreduced, supported catalysts showed excellent catalytic activity and selectivity to butene in the selective hydrogenation of 1,3-butadiene. The calculated total butene selectivity was above 80% for all supported S-1-Pd-1 catalysts compared to 46.92% for a monometallic Pd/ZnO catalyst. In addition, the Ni-1-Pd-1/ZnO catalyst presented the best butene yield of 88.90 %, which was 1.9 times that of the Pd/ZnO catalyst. Moreover, it remained stable over a 10 h durability experiment.