Identifying a superior Ptδ+ species for the hydrogen-borrowing amination of alcohol at low temperature

Abstract

The chemical state of metallic site is crucial for the performance of supported catalysts. Due to the difference of metal-support interaction, the chemical states of the supported metallic species are usually various and identifying the most active site is therefore very important for the design of efficient catalysts. In this work, a superior Ptδ+ species with high positive charge is identified as the active site in the hydrogen-borrowing amination of cyclopentanol with cyclopentylamine via structure and performance relationship study over Pt/CeO2 catalyst. It is found that the lower Pt loaded catalyst (0.74 %Pt/CeO2) has much higher activity than that of the higher Pt loaded one (1.5 %Pt/CeO2). In-situ CO-DRIFTs and XANES studies show that Pt in 0.74 %Pt/CeO2 catalyst has higher positive charge, favoring the dehydrogenation of cyclopentanol to cyclopentanone, the rate-determining step in the whole reaction. Furthermore, a 0.38 %Pt/CeO2 catalyst was prepared, which shows excellent performance at lower temperature (80 °C), the mildest reaction conditions investigated up to now. This work provides a new sight in the design of excellent catalysts for the hydrogen-borrowing amination under mild reaction conditions.