Propylene oxidation to acrolein over Au@MoOx/MoO3 nanobelts driven by oxidative strong metal-support interactions

Supported Au catalysts are widely investigated for selective oxidation processes. Here, propylene oxidation was studied over Au nanoparticles supported on MoO 3 nanobelts. Intriguingly, the Au particles were encapsulated by MoO x layers in oxidizing atmospheres yielding Au@MoO x aggregates which signal non-classical oxidative strong metal-support interaction (SMSI) between Au and MoO 3 . The core@shell particles enhanced the acrolein selectivity of MoO 3 from 18 % up to 81 % while its formation rate accelerated more than twentyfold to 1153 µmol g cat −1 h −1 at 3 wt% Au loading and 350 °C. In situ CO DRIFTS measurements, H 2 -TPR and XPS analyses suggest that the Au@MoO x entities facilitate the transfer of MoO 3 lattice oxygen to propylene in line with the Mars-van Krevelen mechanism for acrolein formation. Apparent activation energies in the 113–163 kJ mol −1 range point to re-oxidation of the ensuing oxygen-deficient MoO x moieties as rate-limiting acrolein formation step. Consequently, the oxidative SMSI strongly promotes propylene conversion to acrolein over MoO 3 -supported Au catalysts.