Bent Carbon Surface Moieties as Active Sites on Carbon Catalysts for Phosgene Synthesis

Active sites in carbon-catalyzed phosgene synthesis from gaseous CO and Cl-2 have been identified using C-60 fullerene as a model catalyst. The carbon atoms distorted from sp(2) coordination in non-planar carbon units are concluded to generate active Cl-2. Experiments and density functional theory calculations indicate the formation of a surfacebound [C-60 center dot center dot center dot Cl-2] chlorine species with radical character as key intermediate during phosgene formation. It reacts rapidly with physisorbed CO in a two-step Eley-Rideal-type mechanism.