Health & Environmental Research Online (HERO)


Print Feedback Export to File
4092199 
Journal Article 
Effective NbOx-Modified Ir/SiO2 Catalyst for Selective Gas-Phase Hydrogenation of Crotonaldehyde to Crotyl Alcohol 
Tamura, M; Tokonami, K; Nakagawa, Y; Tomishige, K 
2017 
ACS Sustainable Chemistry & Engineering
ISSN: 2168-0485 
5 
5 
3685-3697 
WOS:000400634900013 
NbOx-modified Ir/SiO2 catalyst (Ir-NbOx/SiO2) showed high activity and selectivity for gas-phase hydrogenation of crotonaldehyde, and Ir-NbOx/SiO2 with Nb/Ir molar ratio of 0.5 (Ir-NbOJSiO(2) (Nb/Ir = 0.5)) provided high crotyl alcohol yield of 87%. This is the highest crotyl alcohol yield among those in gas-phase over reported heterogeneous catalysts. The activities (TOF per surface lr atom) at low conversion level (40%, W/F = 0.37 g(cat)center dot h center dot mol(-1)) and high conversion level (97%, W/F = 2.2 g(cat)center dot h center dot mol(-1)) were calculated to be 0.21 and 0.08 s(-1), which are more than 3 times higher than those over reported heterogeneous catalysts. High activity and high yield are derived from the combination of Ir metal with NbOx species. Based on the spectroscopic and kinetic studies, the high activity and high selectivity are attributed to strong adsorption of crotonaldehyde on NbOx species by the high Lewis acidity, and suppression of over-hydrogenation of the produced crotyl alcohol at high conversion level. It is suggested that the formation of hydride species at the interface between Ir metal and NbOx species can promote the selective hydrogenation considering the reaction order with respect to hydrogen pressure. High yield and high activity of Ir-NbOx/SiO2 can contribute to energy saving, cost reduction, and waste reduction, which are directly connected to realization of sustainability. 
Selective hydrogenation; Iridium; Unsaturated alcohol; Niobium oxide