Vanadium hydride as an ammonia synthesis catalyst

Year: 2020 DOI: 10.1002/cctc.202001084

Extra Information

Yu Cao, Ayaka Saito, Yoji Kobayashi, HIroki Ubukata, Ya Tang, Hiroshi Kageyama.   ChemCatChem 202013, 191-195.


Early 3d transition metals, such as Ti, V, or Nb are known to be inactive for the Haber-Bosch process, due to their strong M-N bonds. However, recently some hydride compounds have been found to effectively counteract this effect, imparting catalytic activity on a wide range of elements. With these hydride catalysts, hydride (and nitride) bulk diffusion mechanisms have been proposed; if so, more open structures should enhance their activity. Here, we expand the study to hydrides of other early transition metals, V and Nb. These metals benefit from body-centered cubic (bcc) related structures which enhance hydride diffusion, in addition to having relatively lower M-N bond strengths. The activity of vanadium hydride, most likely with an active composition of VH0.44N0.16, is superior to the previously reported BaTiO2.5H0.5, and comparable to TiH2 and Cs-Ru/MgO at 400°C under 5 MPa. These results show that there is more potential for developing new single-phase hydride catalysts of previously overlooked elements without sacrificing activity.