Unraveling the effects of Fe and Mn promoters on the tungstated zirconia catalyst: A DFT study

Abstract

Periodic DFT calculations are performed to unravel the effect of the incorporation of Fe and Mn into the tung-stated zirconia catalyst, (WO3)x/ZrO2 (x = 1,3), in their electronic, geometric, and catalytic properties. Our results suggest that both Mn and Fe have a proclivity to occupy the same positions and thus both metals will compete for the same adsorption sites. The addition of Fe or Mn slightly destabilizes the WO3 monomer while stabilizes the (WO3)3 trimer. Hence, medium size clusters, which are the most catalytically active species, will be more sinter resistant in the presence of the promoters, leading to catalysts with longer lifetimes. The computed deprotonation energies evidence that the overall Bronstead acidity is increased upon the addition of the dopant atoms. It is proposed that the metals lead to a reduction of WZ and induce a local spin density imbalance.The function as redox initiators of these metals is confirmed.