Thermoregulated Phase-Transfer Pd Nanocatalyst for Selective Hydrogenation of 1,5-Cyclooctadiene at Atmospheric Hydrogen Pressure

The surface chemistry of norbornadiene and norbornene on Pd(111) and Pd(100): a comparative DFT study

CONTEXT

The interaction of norbornadiene (NBD) and norbornene (NBE) with the palladium (111) and (100) surfaces have been investigated using density functional theory (DFT). Five configurations of adsorbed NBD may be formed on Pd(111): endo-tetra-σ, endo-di-σ,π, endo-di-π, exo-di-σ, and exo-π. The NBE molecule adsorbed on Pd(111) may exist in 4 configurations: endo-di-σ, endo-π, exo-di-σ, and exo-π. On Pd(100), a smaller number adsorption configurations of NBD and NBE are formed, since the double bonds of these molecules in the endo-orientation are bound only in a di-σ mode. The adsorption energy of NBD and NBE molecules on Pd(100) is noticeably higher compared to Pd(111), which is due to the surface geometry of Pd(100). The most stable configurations on both Pd facets are endo-tetra-σ for NBD and exo-di-σ for NBE. However, due to smaller adsorption area of the exo-di-σ configuration on Pd(111), a larger number of NBD molecules may adsorbed on the same surface area. Energetically favorable endo-tetra-σ (NBD) and exo-di-σ (NBE) configurations are very mobile on Pd(111). On Pd(100), only NBE molecules can migrate, while NBD migration is hindered due to the high activation barrier.

METHODS

All DFT calculations were performed using the Perdew-Burke-Ernzerhof density functional (PBE) with the relativistic SBK effective core potential and TZ2P basis set in the PRIRODA program.

A ruthenium nanocatalyst for the atmospheric hydrogenation of 1,5-cyclooctadiene

A ruthenium nanocatalyst is utilized for the first time for the highly efficient and selective hydrogenation of 1,5-cyclooctadiene under atmospheric hydrogen pressure. Under the optimized reaction conditions, the conversion of 1,5-cyclooctadiene and the selectivity for cyclooctene are >99% and 95%, respectively. The turnover frequency is 451 h−1, which is higher than that ever reported for Ru complex catalysts.