Phenylacetylene hydrogenation on Fe@C and Ni@C core-shell nanoparticles: About intrinsic activity of graphene-like carbon layer in H2 activation

Me@C nanocomposites were prepared by evaporation of overheated liquid drop of Me in the flow of inert gas containing a hydrocarbon. The resulting carbon-coated nickel and iron nanoparticles contain metal cores of about 5 nm in size that are wrapped in a few layers of graphene-like carbon. Experimental data and theoretical results give evidence of the ability of carbon coating in nanocomposites Fe@C and Ni@C to H-2 activation by dissociative adsorption due to the presence of space and structure defects and/or the presence of transition metal in subsurface layer. Since molecular hydrogen dissociation is the key step of hydrogenation reactions, both Ni@C and Fe@C provide high conversion of phenylacetylene (PA) (about 100%) during hydrogenation at the temperatures above 150 and 300 degrees C, respectively. Fe@C provides excellent styrene (ST) selectivity: 86% at 99% PA conversion at 300 degrees C. ST selectivity is moderate on Ni@C (about 60%) in the temperature range of 100-150 degrees C end low at higher temperatures. (C) 2014 Elsevier Ltd. All rights reserved.