ETHYLENE ADSORPTION AND DECOMPOSITION ON PT(210) - CHEMISTRY OF PI-BOUND ETHYLENE

The adsorption and decomposition of ethylene on the Pt(210) crystal surface was examined by using temperature-programmed desorption (TPD) and electron energy loss spectroscopy (EELS). At 100 K, the ethylene adsorbs molecularly on the Pt(210) surfaces to form a "type 2 π-bound" complex with bonding like that in Zeise's salt. Some of the π-bound ethylene desorbs around 250 K, and some reacts to form ethane (C2H6) and adsorbed CH3 groups. However, much of the π-bound ethylene remains on the surface to 300 K. This π-bound ethylene decomposes between 300 and 330 K to form ethan-1-yl-2-ylidyne (μ4≡CCH2-) and hydrogen. Additional hydrogen is liberated upon further heating to produce a mixture of methylene (μ2=CH2), methylidyne (μ3≡CH), ethynyl (μ5≡CCH=), and C2 species ([-C≡C-]x). More π-bound ethylene forms on Pt(210) than on any face of platinum studied previously. Further, π-bound ethylene is stable to higher temperatures than on any other face of platinum studied previously. Thus, we conclude that sites on the Pt(210) surface are especially conducive for the production of π-bound ethylene as expected theoretically. © 1990 American Chemical Society.