Ensemble control has been intensively pursued for decades to identify sustainable alternatives to the Lindlar catalyst (PdPb/CaCO3) applied for the partial hydrogenation of alkynes in industrial organic synthesis. Although the geometric and electronic requirements are known, a literature survey illustrates the difficulty of transferring this knowledge into an efficient and robust catalyst. Here, we report a simple treatment of palladium nanoparticles supported on graphitic carbon nitride with aqueous sodium sulfide, which directs the formation of a nanostructured Pd3S phase with controlled crystallographic orientation, exhibiting unparalleled performance in the semi-hydrogenation of alkynes in the liquid phase. The exceptional behavior is linked to the multifunctional role of sulfur. Apart from defining a structure integrating spatially-isolated palladium trimers, the active ensembles, the modifier imparts a bifunctional mechanism and weak binding of the organic intermediates. Similar metal trimers are also identified in Pd4S, evidencing the pervasiveness of these selective ensembles in supported palladium sulfides.

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Selective ensembles in supported palladium sulfide nanoparticles for alkyne semi-hydrogenation.

Synthesis and Photocatalytic Properties of a Family of CdS‐PdX Hybrid Nanoparticles

0.5 wt.% Pd/C catalyst for purification of terephthalic acid: Irreversible deactivation in industrial plants

Palladium–gold membranes in mixed gas streams with hydrogen sulfide: Effect of alloy content and fabrication technique

Transition metal sulphides show the temperature programmed reduction (TPR) patterns consisting of multiple reduction domains: those at lower temperatures are attributed to the “weakly bonded” sulphur, whereas the “bulk reduction” peaks are usually placed at high temperatures. The present paper is focusing attention on the last type TPR maxima. Due to the positive free energy of reduction of catalytically important sulphides, their TPR at high temperatures is controlled by thermodynamics. For several bulk and supported sulphides, the ascending branch of the “bulk reduction” event might be transformed to a linear (ln[H 2 S]–1/ T ) plot from which standard enthalpy of reduction can be reliably extracted with good precision. Thermodynamics of sulphur abstraction from mixed sulphides (Mo–W sulphides, chromium thiospinels), or from highly dispersed bulk and supported systems can be estimated and compared using this approach.

T. Fujino

Papers

Enthalpies of formation of the palladium sulphides