Coordination and reaction mechanism of furan on Ru(001)

Abstract

The surface chemistry of furan adsorbed on Ru(001) at 80 K has been explored using thermal desorption spectroscopy, x-ray and ultraviolet photoelectron spectroscopies and high resolution electron energy loss spectroscopy (HREELS). Furan adsorption follows a three-dimensional island growth mode. Three desorption peaks, corresponding to multilayer, second layer, and monolayer were identified at 117, 142 and 220 K, respectively. Monolayer species strongly bind to the surface, showing a much lower O(1 s) binding energy (532.9 eV) as compared to the physisorbed furan (534.8 eV). HREELS reveals that within the monolayer, there are two different chemisorbed species with molecular rings oriented either tilted or parallel to the surface. By annealing the surface to 180 K, the parallel furan π complex undergoes α-C electrophilic addition and H elimination, forming the tilted α-furyl species and Ru-H. The α-furyl can either recombine with hydrogen to form furan desorbing between 180 and 250 K, or decompose to give adsorbed oxygen atoms and a metallocyclelike intermediate through a direct oxygen abstraction mechanism. Further thermal annealing leads to the formation of carbon monoxide and hydrogen desorbing from the surface. © 1999 American Institute of Physics.