Effect of Fe, Ga, Ti and Nb substitution in ≈SbVO4 for propane ammoxidation

Substitution in rutile-type ≈SbVO4 was made with Fe3+ and Ga3+ replacing V3+, and Nb5+ replacing Sb5+. Moreover, preparations with Ti were synthesised where Ti4+ ions substitute for both V4+ and V3+/Sb5+ pairs. ≈SbVO4-related phases containing Ti together with Fe and Ga were also prepared. The samples were characterised using X-ray diffraction, DRIFT and Raman spectroscopy. The characterisations show the formation of a cation deficient single rutile-type phase. Use of the samples in propane ammoxidation to produce acrylonitrile reveals, compared with the pure ≈SbVO4 phase, that Fe, Ga and Ti substitution in ≈SbVO4 results in lower activity but considerably higher selectivity to acrylonitrile at the same level of propane conversion. Niobium substitution, on the contrary, gives no improved catalytic properties. Correlations are presented between the catalytic and structural properties of the catalysts. It is demonstrated that isolation in the structure of the propane activating V–O. sites in a surrounding of nitrogen inserting Sb-sites results in improved selectivity for acrylonitrile formation.

Propane ammoxidation to acrylonitrile is studied over unsubstituted ≈SbVO4 and its substitutions with Fe, Ga, Ti and Nb. The catalytic data indicates that a catalyst selective to acrylonitrile should have structurally isolated ensembles with propane activating V-sites and nitrogen inserting Sb-sites.Figure optionsDownload high-quality image (192 K)Download as PowerPoint slide