Structural selectivity of supported Pd nanoparticles: selective ethanol ammoxidation to acetonitrile†

Abstract

The need to achieve net zero requires decarbonisation across all areas of our industrialised society, including the production of chemicals. One example is the production of acetonitrile, which currently relies on fossil carbon. Recently, supported Pd nanoparticles have been shown to promote the selective transformation of bio-derived ethanol to acetonitrile. Elsewhere, current research has demonstrated the importance of interstitial structures of Pd in promoting specific transformations. In this study, we demonstrate through a spatially resolved operando energy-dispersive-EXAFS (EDE) technique that selectivity to acetonitrile (up to 99%) is concurrent with the formation of a PdN_x phase. This was evidenced from the features observed in the X-ray absorption near edge structure that were validated against PdN_x samples made via known synthesis methods. Above 240 °C, the Pd nanoparticles became progressively oxidised which led to the production of unwanted byproducts, primarily CO₂. The spatially resolved analysis indicated that the Pd speciation was homogeneous across the catalyst profile throughout the series of studies performed. This work resolved the structural selectivity of Pd nanoparticles that directs ethanol ammoxidation towards acetonitrile, and provides important information on the performance descriptors required to advance this technology.