Propylene Oxidation to Acrolein over Cu/MoO3 Nanobelt Composites

Nanocomposites comprised of MoO3 nanobelts with Cu6Mo5O18 derived surface layers are very active for propylene oxidation to acrolein with selectivity approaching 60% between 350–400 °C. They offer high surface areas (∼18 m2 g−1) and yield acrolein formation rates exceeding those of unpromoted bismuth molybdates which are the basis of industrial catalysts. Their acrolein selectivity is also markedly higher than that of the Cu2+ molybdates α‐CuMoO4 and Cu3Mo2O9. XPS and TPR analyses point to the formation of a Cu+ containing molybdate on the MoO3 nanobelt surfaces which is identified as Cu6Mo5O18 by its unique Raman bands. Kinetic analyses suggest that this surface layer facilitates catalyst re‐oxidation which remains the rate‐determining step of acrolein formation over the nanocomposites up to 400 °C. Thus, the nanocomposites present a very efficient copper molybdate catalyst design for propylene oxidation to acrolein which is also less susceptible to carbon induced deactivation than bulk Cu2+ molybdates. Nanocomposite catalyst: A Cu6Mo5O18 derived molybdate skin turns MoO3 nanobelts into very active catalysts for selective oxidation of propylene to acrolein. The surface layer facilitates re‐oxidation of the Cu/MoO3 composite which enables faster transfer of lattice oxygen to reaction intermediates and thus favors their conversion into acrolein.