Catalytic performance of palladium nanoparticles encapsulated within nitrogen-doped carbon during Heck reaction

The Confinement effect is an effective strategy for enhancing the performance of catalysts during various reactions. We developed a strategy to encapsulating Palladium nanoparticles with a dopamine-derived N-doped multilayer carbon shell to catalyze the Heck reaction between iodobenzene and carbon-carbon double-bond compounds (styrene and methyl acrylate). The catalytic performances of Pd nanoparticles encapsulated within a N-doped carbon layer (Pd@N-C) and those attached to the external surface of such a layer (Pd/N-C) were evaluated and compared. Pd@N-C exhibited a lower reaction activation energy (78 kJ/mol) than that of Pd/N-C (106 kJ/mol). Thus, the activity of Pd@N-C during the Heck reaction between iodobenzene and methyl acrylate was approximately 20 times higher than that of Pd/N-C-200. The results of thermal filtration and recycling tests indicated that Pd@N-C showed a lower degree of leaching than that of Pd/N-C-200 owing to the spatial restriction effect of the cavity in the case of the former. Hence, the superior catalytic performance of Pd@N-C can be ascribed to the confinement of the Pd nanoparticles within the N-doped carbon layer. Finally, we used these catalysts to synthesize a range of para-substituted iodobenzene derivatives, thus demonstrating the potential of Pd-encapsulating catalysts for use in the Heck reaction on the technical scale. (c) 2021 Elsevier Inc. All rights reserved.

Automated summary

The Confinement effect is an effective strategy for enhancing catalyst performance during reactions. Encapsulating palladium nanoparticles within a N-doped carbon layer resulted in lower reaction activation energy and higher catalytic activity compared to palladium nanoparticles attached to the external surface of the layer. The superior catalytic performance of Pd@N-C can be attributed to the spatial restriction effect of the cavity in the case of the former, leading to lower leaching and improved catalytic efficiency.