(98e) Interaction of Ethylene and Nitrogen Atoms On the Pt (111) Surface

The selective catalytic reduction (SCR) of NOx by hydrocarbon on noble metals is critically important to the implementation of leaner burning more fuel efficient processes. Understanding the reaction mechanisms and pathways is essential for designing an effective catalytic system. As one small part of this effort, we focus on the interaction of nitrogen atoms and simple alkenes such as ethylene on Pt(111) surface under UHV conditions in an effort to understand the potential intermediates in NOx reduction. The adsorption of ethylene on nitrogen pre-covered Pt (111) surface has been investigated using by reflection absorption infrared spectroscopy (RAIRS) and thermal desorption spectroscopy (TDS) as well as density functional theory calculations. Two interesting observations have been made. First, we observe the presence of π-bonded ethylene below 220 K. indicating a switch in the preferred binding site for ethylene on N-Pt (111) as compared to the clean surface. Second, above 500 K,CN coupling occurs and ammonia is seen to desorb. The appearance of ammonia is believed to be the result of a reaction between N atoms (or NH) with coadsorbed ethylidyne.