METHANE FORMATION DURING ETHYLENE DECOMPOSITION ON (1X1)PT(110)

Previous work on the decomposition of ethylene on a variety of single-crystal surfaces and inorganic clusters indicates that the carbon-carbon bond usually stays intact until after the ethylene is largely dehydrogenated. However, in this paperwe find that when ethylene adsorbs on (1⨯1)Pt(l 10), the carbon-carbon bond breaks near room temperature yielding methane. The methane desorbs in two peaks centered at 250 and 320 K. There also is evidence for production of a species containing CH3 groups between 220 and 250 K. By comparison no significant production of methane has been observed during ethylene decomposition on any face of any transition metal studied previously. No methane formation is observed during ethylene decomposition on (2⨯1)Pt(110) even though all of the sites present on (1⨯1)Pt(l 10) are also present on (2⨯1)Pt(110). Thiskind of remarkable structure sensitivity has not been observed previously. We propose a speculative mechanism to explain these results involving some special steric hindrances on the (2⨯1)Pt(110) surface. © 1990, American Chemical Society. All rights reserved.