SFB 546 II-III: DFT calculations on structure, vibrational spectra and reactivity of different vanadium oxide aggregate (TP A 4)


In the previous funding period finite-size models for vanadium oxide species on SiO2 supports have been designed and successfully tested. In cooperation with projects B1 and B3 we were able to solve the problem of the correct assignment of Raman bands to isolated monomeric and dimeric vanadium oxide species on SiO2 and Al2O3 supports.
The structure predictions for V2O5 clusters in the gas phase, previously made by DFT, have been confirmed by spectroscopic experiments in project A3 and by ab initio calculations in project A1.
Dissociation of the vanadyl (V=O) bond has been chosen as test reaction for reactivity differences between gas phase V2O5 clusters and cluster ions, V2O5 surface species on supports and surfaces of crystalline V2O5. The observed support effects can be explained by supression of structure relaxations that are possible in crystalline V2O5 and by electronic site isolation.
In the next period quantum chemical studies will focus on elementary catalytic steps and again, comparison will be made between gas phase clusters (see also projects A2 and A3), supported species and surfaces of bulk materials (projects B2 and B3) . The studies on supported species, in additon to SiO2 and Al2O3, will include a support material that is known to increase the activity of the catalyst compared to pure V2O5 such as TiO2. Different local structures of the supporting oxides will be studied by QM/MM hybrid methods. The following reactions will be considered: oxidation of methanol to formaldehyd (some results already available) and oxidative dehydrogenation of propane yielding propene. To deepen the understanding of reactivity, some comparison will be made with other transition metal oxides (Niobium, Molybdenum).

Principal Investigators
Sauer, Joachim Prof. Dr. rer. nat. Dr. h.c. (Details) (Collaborative Research Centre 546 'Transitional Metal Oxide Aggregates')

Duration of Project
Start date: 07/2002
End date: 06/2011

Last updated on 2020-10-03 at 16:30