Hydrogenation of pentenal over supported Pt nanoparticles: influence of Lewis-acid sites in the conversion pathway

Abstract

In this study, we prepare three supported Pt NP catalysts (Pt/CeO₂, Pt/Al₂O₃, and Pt/CeAl), which are characterized by XRD, TEM, Raman, N₂-sorption, and XPS. The Pt/CeAl catalysts show the best catalytic performance (52% conversion and 80% 2-pentenol selectivity) with a maximum TOF of 19896 mmol_{convert pentenol} mmol_{Pt sites}⁻¹ h⁻¹ in 2-pentenal hydrogenation. A distinct support effect is observed. Incorporating Al into ceria is favourable towards the formation of medium Lewis acidic sites. 2-Pentenal is converted initially to 2-pentenol via the hydrogenation of the CO bond and then to pentanol, as the unsaturated Ce⁴⁺/Al³⁺ cations originated from Ce⁴⁺–O–Al³⁺ pairs act as the acid sites and electron acceptors to polarize CO bonds, which could facilitate 2-pentenal intramolecular nucleophilic addition toward the C^δ+ site to form 2-pentenol rapidly. This study may give some hints for the further development of effective nano-Pt catalysts in selective hydrogenation to prepare valuable chemicals.