Propylene Oxidation to Acrolein over Cu/MoO₃ Nanobelt Composites

Abstract 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.