Benzene decomposition on the Rh(111) crystal surface has been studied over the temperature range of 300-800 K by high-resolution electron energy loss spectroscopy (HREELS), temperature-programmed desorption (TPD), and low-energy electron diffraction (LEED). Our results show that benzene decomposition begins at 400 K, forming a mixture of CH and C2H species. The relative amounts of these two species vary with temperature; at 470 K, the concentration ratio of CH to C2H is 0.4. Above 500 K, these fragments dehydrogenate and condense to form CnH polymers. By 800 K, the adsorbed monolayer is completely dehydrogenated, forming a polymeric carbon monolayer with a vibrational spectrum similar to that of an ordered graphite monolayer. We propose that benzene decomposition on Rh(111) proceeds by decyclotrimerization to form three acetylenes which immediately decompose to CH and C2H species.
All Science Journal Classification (ASJC) codes
- Physical and Theoretical Chemistry