(669b) Design of Palladium-Gold Catalysts for Liquid Phase Selective Alkyne Hydrogenation with Single Atom Alloy Strategy

Gold (Au) nanoparticles (NPs) catalysts have been found to be very selective in catalyzing the partial hydrogenation of alkynes, however, are known for low activity in hydrogen activation. We applied single atom alloy (SAA) strategy in design of gold catalysts for selective hydrogenation of alkynes to alkenes, which is a very important process for producing polymer grade alkenes. In Pd-Au SAA, atomically dispersed palladium (Pd) atoms are added into the surface of gold NPs that activate the gold for hydrogenation and maintain the high selectivity to alkenes. Previous studies have demonstrated the bi-functional hydrogenation mechanism on Pt-Cu SAAs that Pt atoms dissociate H₂ and Cu surface catalyzes the hydrogenation. Here we proposed that Pd atoms can improve the H₂ activation activity of gold NPs but do not affect the highly selective hydrogenation chemistry on gold.

We have investigated the selective hydrogenation performance of Pd-Au SAAs. The Pd-Au SAAs enhance activity in liquid phase partial hydrogenation of 1-hexyne and phenylacetylene. The Pd-Au SAA NPs were synthesized by sequential reduction in ethylene glycol with PVP as stabilizing ligand. ATR-IR of adsorbed CO indicates there is no bridge CO on Pd-Au SAA NPs, which proves the formation of SAA. The batch reactor hydrogenation tests show more than 80% selectivity to partial hydrogenation products at full conversion and at least 5-fold increase in activity by doping Au NPs with 0.4% Pd atoms. The preparation, reactivity, and characterization of the alloy nanoparticles with ATR-IR, electron microscopy and X-ray absorption techniques will be presented.

Acknowledgments: This work was supported as part of the Integrated Mesoscale Architectures for Sustainable Catalysis, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, under award #DESC0012573.