Catalytic Behavior of Graphite Nanofiber Supported Nickel Particles. 2. The Influence of the Nanofiber Structure

Abstract

The hydrogenation of ethylene, 1-butene, and 1,3-butadiene has been used as a probe reaction in an attempt to monitor any possible changes in catalytic behavior induced by supporting nickel on different types of graphite nanofiber support materials. This study is designed to compare the catalytic behavior of the metal particles when dispersed on three types of nanofibers, where the orientation of the graphite platelets within the structures is significantly different in each case. The metal crystallites are located in such a manner that the majority of particles are in direct contact with graphite edge regions. It should be emphasized, however, that there are subtle differences in the spacing between adjacent exposed carbon atoms in the various nanofiber structures. As a consequence, it is highly probable that the atomic arrangement of the surfaces of nickel particles that nucleate on these different graphite edges will be dictated to a large degree by the interaction with the atoms in nanofiber supports. Under such circumstances one might reasonably expect that different crystallographic faces of nickel will be exposed to the reactant gas depending on which type of nanofiber structure is used as the supporting medium. For comparison purposes, the same set of hydrogenation reactions were carried out under similar conditions over γ-alumina supported nickel particles.

Bio-oil upgrading in supercritical water using Ni-Co catalysts supported on carbon nanofibres

“…These include the hydrogenation of light alkenes [23][24][25][26][27], aldehydes [21,[28][29][30][31][32][33], polycyclic aromatic hydrocarbons [34], nitrobenzene [35], and cyclohexene [36]. They have also been used in alkene hydroformylation [37], vacuum residue hydroprocessing [38,39], ammonia and Fisher-Tropsch synthesis [40][41][42], cyclohexanol dehydrogenation [43], NO decomposition [44] and aniline oxidation [45,46].…”

Preparation and Activity of Small Rhodium Metal Particles on Fishbone Carbon Nanofibres

“…Furthermore, with particles of this size, metalsupport interactions can be studied. Several researchers found increased activities or selectivities when carbon nanofibres or nanotubes were used as the support (7)(8)(9)(10)(11)(12)(13). More information about the interaction between the metal and the CNF support could shed some light on these phenomena.…”

“…Again, activity improvement compared to that of nickel metal on classical supports was obtained in the hydrogenation of 1-butene and 1,3-butadiene (8). Furthermore, differently structured carbon nanofibres displayed different activities and selectivities (9). Preferential blocking of either the armchair or the zigzag graphitic edge faces with P or B, respectively, indicated that the effects could be ascribed to the catalytic action of Ni residing on the zigzag faces (10).…”

“…The metal and support of the catalyst originally used to grow the CNFs, however, have to be removed after synthesis. Investigation of use of carbon nanotubes and carbon nanofibres as catalyst support has only started recently (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15). Carbon nanotubes are mostly used to study the effects of this novel carbon material on the properties of the final supported catalyst.…”

“…The authors pointed out the possible relationship between this activity enhancement and a unique metalsupport interaction between the metal particles and the basal planes of the fibres. In later publications (8)(9)(10), Ni was impregnated on CNFs, resulting in 6-to 8-nm-size particles. Again, activity improvement compared to that of nickel metal on classical supports was obtained in the hydrogenation of 1-butene and 1,3-butadiene (8).…”