Selectivity difference between hydrogenation of acetophenone over CNTs and ACs supported Pd catalysts

Selectivity difference between hydrogenation of acetophenone over carbon nanotubes (CNTs) and commercial activated carbons (ACs) supported Pd catalysts has been investigated. The selectivity of α-phenylethanol over the Pd/CNTs catalyst is significantly higher than that over the Pd/ACs. The optimal yield of α-phenylethanol over the Pd/CNTs catalyst is 94.2% at 333 K under atmospheric H2 pressure for 255 min, but it is only 47.9% over the Pd/ACs catalyst. HRTEM characterization and density functional theory (DFT) study of the two catalysts suggested that the defects of the carbon support are the main anchoring sites for Pd nanoparticles. Additionally, mechanistic study of the acetophenone hydrogenation over the two catalysts suggested that the different adsorption modes of reaction intermediates (products) on the two kinds carbon supported Pd nanoparticles are responsible for the dramatic selectivity difference.

The catalytic hydrogenation of acetophenone over the Pd/CNTs catalyst shows significantly higher (-phenylethanol selectivity than that over the Pd/ACs catalyst due to the different adsorption modes of the reaction intermediates on the two kinds of catalysts.Figure optionsDownload high-quality image (86 K)Download as PowerPoint slideHighlights
► High selective acetophenone hydrogenation over Pd/CNTs was observed.
► Selectivity of α-phenylethanol is ∼95% on Pd/CNTs and ∼5% on Pd/ACs.
► Pd nanoparticles were mainly adsorbed on the defects of both the CNTs and ACs support.
► Different adsorption modes of the α-phenylethanol on Pd nanoparticle lead to the selectivity difference.