Simulation of propylene to propylene oxide conversion via silver nanoclusters supported on an alumina surface.
Propylene oxide is an important chemical whose current industrial production is energy intensive and environmentally unfriendly. Attempts to solve this problem by using catalysts based on bulk silver surfaces with direct propylene epoxidation by molecular oxygen have not been successful because of substantial carbon dioxide formation. Unpromoted, size- selected Ag3 clusters and ~3.5 nm silver nanoparticles on alumina supports catalyze this reaction with only a negligible amount of carbon dioxide and unprecedented activity at low temperatures. Density functional calculations show that oxidized silver trimers are more active and selective for epoxidation compared to extended silver surfaces because of the open-shell nature of their electronic structure. The results suggest that new architectures based on ultrasmall silver particles may provide highly efficient catalysts for propylene epoxidation. The experimental and theoretical analysis efforts were led by researchers in CNM's Nanophotonics and Theory & Modeling groups, respectively. (More...)
Y. Lei et al., "Increased Silver Activity for Direct Propylene Epoxidation via Subnanometer Size Effects," Science, 328:5975, 224-228 (April 9, 2010) (online)
L..Curtiss et al., “Tiny trimer, big result,” The Chemical Engineer, 829/30, 46-48, July/August 2010 (online with permission)