Optimization of Pd in Au-Pd nanoparticles for the hydrogenation of alkynes

13 January 2023, Version 1
This content is a preprint and has not undergone peer review at the time of posting.

Abstract

Supported Au-Pd nanoparticles are an excellent catalyst for the hydrogenation of alkynes, a crucial step for olefin polymerization. They have better selectivity at a high conversion rate for the hydrogenation of 1-hexyne compared to pure Pd. The size, shape, and composition of the supported catalyst ultimately determine their properties. In this work, a combined scanning transmission electron microscopy (STEM) and density functional theory (DFT) study is used to determine how Pd concentration affects the activity and selectivity of Au-Pd particles for the hydrogenation of acetylene. Atomic resolution microscopy shows the increased probability of Pd-rich islands within particles with increasing Pd concentration. DFT models of the surface concentrations of Pd as monomers, dimers, and trimers allowed insight into the origin of the high activity for ethylene production. Specifically, monomers of Pd were found to be more active than dimers and trimers. This provides insight into why Au1-xPdx particles with low Pd concentration have higher production rates, as Pd monomers are more statistically likely. These combined STEM and DFT results explain the existence of an optimum for Au:Pd ratio, where conversion per gram of Pd is maximized at a concentration of 4 % Pd.

Keywords

Au-Pd nanoparticles
TEM
DFT
optimization

Supplementary materials

Title
Description
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Title
Supporting Information for main manuscript
Description
Additional TEM images, details about DFT and microkinetic simulations
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