Novel Ammoxidation Catalysts based on Vanadium Containing Oxynitrides. Impact of Structure on the Catalytic Performance

The potential of a new catalyst class based on vanadium containing oxynitrides has been explored in the ammoxidation of 3-picoline (3-PIC) to 3-cyanopyridine (3-CP). So far, mixed oxides of the type SbVTiSiO belong to the best catalysts for this reaction, however, space-time yields (STY) did not exceed 150 g/lh. Improving STY while maintaining high 3-CP selectivity would be energetically most sustainable. Therefore, ternary VAlZrON and VZrPON, binary VMoON and VSbON oxynitrides as well as VMON/MoxOyNz (M = Al or Zr) catalysts have been investigated for their catalytic performance and structure-reactivity relationships. With VZrAlON catalysts, highest STY values ever measured have been obtained, while VSbON catalysts bear a great potential, too. By spectroscopic multimethod analysis, applied ex and in situ, structure-reactivity relationships have been proposed. The presence of direct V-N junctions and anionic surface defects are essential for high nitrile selectivity. This is the best fulfilled for VZrAlON, VMoON and VSbON catalysts.