ABSTRACT
Previously, this group has reported the effect of external hydrogen on aniline hydrogenolysis on the Pt (111) surface [1]. Carbon-nitrogen bond activation is substantially enhanced on the P t( ll l) surface in the presence of hydrogen. The increased C-N bond cleavage in hydrogen is facilitated by a parallel configuration of the aromatic ring at reaction temperature. While in the absence of surface hydrogen, the adsorbed intermediate tilts away from surface because of partial dehydrogenation with increasing temperature at about 400 K. On evaporated nickel film, aniline adsorbs both molecularly via the π-electrons and dissociatively via an anion formed by the release of a proton from the amino group [3]. On both the Ni(100) and N i(lll) surfaces, adsorbed aniline was reported to form a strongly bound surface species at relatively high temperatures, postulated to be poly aniline [4, 5]. Polymerization occurs when the positively charged ring carbon atoms, upon electrophilic attack from nickel, react with the nitrogen on adjacent adsorbed aniline molecules. This polymerized species is very stable on the nickel surfaces, and does not decompose till above 600 K. This paper will present our recent study of aniline reactions on the Ni(100) and N i( ll l) surfaces both in the presence and absence of hydrogen. Reactivity comparisons will also be made for these two nickel surfaces towards adsorbed aniline.
