Formation of Benzonitrile from the Reaction of Styrene with Nitrogen on the Pt(111) Surface

Abstract

Temperature-programmed reaction spectroscopy (TPRS) and reflection absorption infrared spectroscopy (RAIRS) were used to investigate the adsorption and reaction chemistry of styrene with clean and nitrogen covered Pt(111). The RAIR spectra indicate that the adsorption geometry of styrene is altered by both coverage effects and by the presence of nitrogen atoms on the surface. For an annealed monolayer of styrene on the clean Pt(111) surface, the most intense peaks correspond to out-of-plane bending vibrations indicating that the molecular plane is oriented parallel to the surface. For monolayer styrene on the nitrogen-precovered surface and for an unannealed monolayer of styrene, the in-plane and out-of-plane vibrations have comparable intensities indicating a more random orientation of the molecular plane. Upon heating, styrene reacts with the coadsorbed nitrogen atoms to form benzonitrile, which desorbs at 380 K. When benzonitrile is directly adsorbed on the Pt(111) surface, TPRS and RAIRS reveal that it desorbs at 350 K, indicating that its desorption at 380 K when formed from the reaction of styrene with nitrogen is reaction limited.