Defining the Qualities of High-Quality Palladium on Carbon Catalysts for Hydrogenolysis

Abstract

Palladium-catalyzed hydrogenolysis is often the final step in challenging natural product total syntheses and a key step in industrial processes producing fine chemicals. Here, we demonstrate that there is wide variability in the efficiency of commercial sources of palladium on carbon (Pd/C) resulting in significant differences in selectivity, reaction times, and yields. We identified the physicochemical properties of efficient catalysts for hydrogenolysis: (1) small Pd/PdO particle size (2) homogeneous distribution of Pd/PdO on the carbon support, and (3) palladium oxidation state are good predictors of catalytic efficiency. Now chemists can identify and predict a catalyst’s efficiency prior to the use of valuable synthetic material and time.

Pd4O3 Subsurface Oxide on Pd(111) Formed during Oxygen Adsorption-Induced Surface Reconstruction and Its Activity toward Formate Oxidation Reactions

“…In contrast, a previous study suggested that the Pd/C catalyst with poor catalytic activity has a higher PdO content; in other words, the formation of PdO will significantly reduce the catalytic activity. Some Pd-based nanoalloy catalysts , improved the catalytic activity toward the FOR due to the formation of the Ag–O and Rh–O species.…”

“…Oxygen atoms occupy the catalytic active sites on the surface, which increases the limiting potential of the FOR, thereby reducing the catalytic activity. Figure S3 In contrast, a previous study 69 suggested that the Pd/C catalyst with poor catalytic activity has a higher PdO content; in other words, the formation of PdO will significantly reduce the catalytic activity. Some Pd-based nanoalloy catalysts 5,6 improved the catalytic activity toward the FOR due to the formation of the Ag−O and Rh−O species.…”

Recent Advances of Pd/C-Catalyzed Reactions

“…Due to its catalytic efficiency, easy recyclability, and diverse catalytic modes, the Pd/C catalyst has found, and will continue to find, valuable applications in the catalysis of organic reactions. It is worth pointing out that there is wide variability in the efficiency of commercial sources of Pd/C, resulting in significant differences in selectivity, reaction times, and yields [95]. On the other hand, it is still a significant challenge to explore the solution for the Pd/C catalyst's progressive deactivation upon successive reuses when, due to palladium leaching, the catalyst is hard recycled after a few times, and thus, it becomes inactive or much less active.…”

A unified approach to the synthesis of amines through a highly selective and broadly applicable imine reduction using modified Pd-nanoparticles

“…Recent studies have demonstrated that commercial Pd/C consists of bulk metal and metal nanoparticles of highly variable size, shape and oxidation state, and thus there is often significant variability in the reactivity of different sources and batches. 17 The lot-lot-variability constitutes a burden on academic and industrial chemists, adding to the cost and reliability of synthesis. The safe handling, disposal and recycling of Pd/C at scale also poses challenges at commercial scale.…”