Dehydration of Amides to Nitriles over Heterogeneous Silica-Supported Molybdenum Oxide Catalyst

Silica-supported molybdenum oxide (MoOx/SiO2) with 4.8 wt% Mo (0.5 mmol g(-1)) was an effective and reusable heterogeneous catalyst for dehydration of 2-furamide to 2-furonitrile (96 % yield). The catalyst was applicable to the dehydration of various amides including heteroaromatic, aromatic and alkyl amides, providing the corresponding nitriles in high yields (87-97 %). Based on the results of catalyst characterizations (XRD, TEM, UV-vis, Raman) and activity tests, MoOx species are highly dispersed over SiO2, and heptamolybdate anion ([Mo7O24](6-)) and isolated dioxo ((O=)(2)MoO2) were mainly formed on the SiO2 support of the optimal MoOx/SiO2 catalyst. The strong Bronsted acid sites (Mo-OH-Si site) can be formed from the MoOx species and the adjacent silanol group, and the acid-base pair site (Mo(=O)-OH-Si site) of the strong Bronsted acid site (Mo-OH-Si site) and base site (Mo=O) over MoOx/SiO2 catalyst could be the main active site for the dehydration of amides.