Deuteron NMR study of the conversion of vinylidene to ethylidyne: evidence for support effects in platinum-alumina catalysts

Abstract

The authors have used deuterium NMR to study the conversion of vinylidene (CCH{sub 2}), the stable room-temperature species formed from acetylene adsorbed on Pt, plus hydrogen to ethylidyne (CCH{sub 3}). These experiments were performed using small Pt metal clusters supported on {eta}-alumina typical of industrial catalysts. For temperatures above 300 K, exchange between hydrogen atoms in the product ethylidyne surface species was observed. The authors also show that adsorption of C{sub 2}H{sub 2} on the Al{sub 2}O{sub 3} support makes a negligible contribution to the {sup 13}C signal, confirming earlier work by Wang, contrary to results quoted by Ellis et al. for magic angle spinning studies.