Comparison of Pd and Pd4S based catalysts for partial hydrogenation of external and internal butynes

Abstract

The partial hydrogenation of but-1-yne and but-2-yne was studied with a view to probing the difference between external and internal alkynes. Catalysts with Pd and Pd4S active phases were prepared on a carbon nanofiber support. Over the simple Pd catalyst over-hydrogenation was common which restricted alkene selectivity greatly -25-35% depending on temperature. In contrast, the Pd4S active phase offered exceptional alkene selectivity (maximum of 92-93% alkene selectivity for both the external and internal alkyne).DFT calculations were subsequently used to rationalise this difference in product selectivity -sulfur appears to change the geometry of the active site in Pd4S and create a surface which favours alkene desorption relative to over-hydrogenation. This work further emphases the potential of palladium sulfide phases as an alternative to purely metallic palladium catalysts for partial alkyne hydrogenation.

Field-induced reagent concentration and sulfur adsorption enable efficient electrocatalytic semihydrogenation of alkynes

“…Pd 4 S, surface thiolate–modified Pd (denoted as ArS-Pd), and their combination (denoted as ArS-Pd 4 S) are chosen for comparisons because Pd 4 S is the most stable among various palladium sulfides with high hydrogenation activity (fig. S1) ( 28 , 29 ), while the organic sulfur modification is a common and efficient route to improve the thermocatalytic performance of Pd catalysts ( 30 ).…”

Adsorbate-Induced Structural Evolution of Pd Catalyst for Selective Hydrogenation of Acetylene

“…Meanwhile, Pd hydride phases can form (-PdH and -PdH) in the presence of hydrogen resulting in the formation of reactive subsurface hydrogen which enhances ethylene hydrogenation upon migration back to the surface 6,7 . A broad range of alternative catalyst formulations for improving selectivity to ethylene by inhibiting -PdH phase have been reported in recent years including alternative monometallic 8,9 , bimetallics 10,11 , metal oxides 12 , sulfides 13,14 and phosphides 15,16 , although in many cases application is limited. For example, operation at shorter time on stream, higher temperature and/or lower pressure than current reactors permit mean they are not necessarily 'drop-in' replacements.…”

Biotechnological synthesis of Pd-based nanoparticle catalysts

“…81,97 On the other hand, due to the relatively low proportion of sulydryl binding sites in live cells, Pd-S formation in bio-Pd may actually be relatively low and this could even contribute to enhanced catalytic activity or selectivity. [98][99][100][101] 4.2 Bio-Pd in dissimilatory metal-reducing bacteria (DMRB)…”