The manufacture of chemicals requires innovation at the catalyst frontier so that processes can be developed with higher energy efficiency and increased facility of separation and recovery of products. Catalysts with high selectivity and activity control the overall efficiency of a process by avoiding unwanted side-reactions and increasing the conversion per unit time. Although processes catalysed by homogeneous catalysts have the advantage of offering better control and understanding of the reaction mechanism, their frequent dependence on expensive metals which are difficult to recover, often precludes their employment in large-scale applications. Heterogeneously catalysed reactions on the other hand, are not associated with problems regarding recycling and reuse of catalyst, contamination of products or intermediates. This work reports the synthesis, characterization and testing of Pd-Sn nanoalloy catalyst in the selective hydrogenation of 2-methyl-3-butyn-2-ol. Our results show that the Pd-Sn nanoalloy, of composition Pd2.8Sn, supported on ZnO (Pd2.8Sn/ZnO), offers very high activity and selectivity in the semi-hydrogenation of 2-methyl-3-butyn-2-ol to 2-methyl-3-buten-2-ol in the liquid phase. Under identical reaction conditions, Pd2.8Sn/ZnO shows activity, both turnover frequency and activity normalized by Pd content, significantly higher than Pd/CaCO3 (the Lindlar catalyst), with TOF of 137.6 s−1 compared to 79.2 s−1 for Pd/CaCO3 with approximately equal selectivity. The preparation of Pd2.8Sn/ZnO is achieved using a one-pot polyol procedure with the addition of a capping agent (polyvinylpyrrolidone) to control the particle size distribution. TEM shows nanoparticles evenly dispersed on the support, with a size distribution of 4.06 ± 0.75 nm. Single phase Pd2.8Sn was also prepared without the ZnO support, via the polyol method. Powder X-Ray diffraction data from the unsupported nanoalloy shows that the unit cell of Pd2.8Sn is face centred cubic with the Pd and Sn atoms occupying randomly the same crystallographic position. The chemical formula was calculated from a combination of ICP and PXRD analyses.
Ibhadon, A. O., Francesconi, M. G., & Johnston, S. K. (2017). Nanoparticulate Pd-Sn Compounds Supported on Metal Oxides: Synthesis, Material and Catalytic Properties. Chemical Engineering & Process Techniques, 3(3),