(769d) Visible Light Enhanced Selective Propylene Epoxidation Over Copper Based Catalyst

Developing energy efficient, environmentally friendly chemical transformation processes is of paramount importance for combating dwindling natural resources and growing environmental concerns.  Propylene oxide (PO) is an extremely valuable commodity chemical that is still commercially produced using expensive, environmentally harmful routes, due to the difficulties associated with developing heterogeneous catalytic materials that can directly produce PO using oxygen or air as an oxidant.  The development of an environemtnally friendly and selective direct heterogeneous process for producing PO represents a major potential advancement.
In this contribution, we demonstrate that copper based catalysts exhibit high selectivity in the direct epoxidation (using O2 as an oxidant) of propylene to form PO. We also demonstrate that the nanostructured copper catalyst can efficiently couple low intensity visible light with thermal energy to drive propylene epoxidation at significantly lower temperature than epoxidation under pure thermal conditions.  The critical feature of the copper catalysts that allows it to effectively channel photon energy into chemical energy is its strong surface plasmon resonance.  The effect of illumination on PO selectivity and process kinetics will be discussed in the context of the molecular mechanisms that govern the photocatalytic process.