| AVS 57th International Symposium & Exhibition | |
| Surface Science | Monday Sessions |
| Session SS1-MoM |
| Session: | Reactivity and Selectivity on Catalytic Surfaces |
| Presenter: | J. Yin, University of Illinois at Chicago |
| Authors: | J. Yin, University of Illinois at Chicago R. Meyer, University of Illinois at Chicago M. Trenary, University of Illinois at Chicago |
| Correspondent: | Click to Email |
The selective catalytic reduction (SCR) of NOx by hydrocarbons 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 the Pt(111) surface under UHV conditions in an effort to understand the potential intermediates in NOx reduction. The adsorption of ethylene on a nitrogen pre-covered Pt(111) surface has been investigated using reflection absorption infrared spectroscopy (RAIRS) and thermal desorption spectroscopy (TDS) as well as density functional theory calculations. Three interesting observations have been made. First, we observed 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 as indicated by the desorption of HCN and the identification of CNH2 with RAIRS. Third, the formation of ammonia is observed through NH3 desorption as well as by observation of the ds (NH3) mode of NH3 at ~1170 cm-1 with RAIRS. The appearance of ammonia is believed to be the result of a reaction between N atoms (or NH) with coadsorbed ethylidyne.