used to probe the activity of catalysts for reactions
taking place on metal sites. Moreover, this reaction
is of practical interest as special attention has recently
been focused on the hydrogenation of aromatic
compounds and there is an increasing demand for suppression
of the benzene content in petroleum fuels and
especially in gasoline and diesel in the near future.
The support used to disperse a metal has a significant
effect on the catalyst activity for hydrogenation of
benzene. Various forms of interaction between active
metal and support materials in supported metal catalysts
have been cited in the literature to explain
experimental observations. In cases where metal aggregates
are smaller than 1 nm and nearly molecular in
character, interaction with the support can be stronger
and more complex [17]. It has been observed that the
activity of very small metal clusters may be lower
in comparison to larger clusters [18]. Therefore, for
the hydrogenation of benzene, which is frequently regarded
as a structure insensitive reaction on supported
metals sites [6,19–22], there are some divergences,
particularly in the case of small metal particles. Moreover,
data indicating divergences from structure insensitivity
have appeared in several studies particularly
on nickel catalysts [23–25], but also on other metals
deposited on various supports [4,18,26–28].
Supported nickel catalysts are used for hydrogenation
reactions of industrial interest, like hydrogenation
of aromatics, organic synthesis and hardening of fats.
The choice of nickel is mainly due to its availability
and reasonable cost, compared to noble metals. The
industrial catalysts very often contain high percentage
of nickel supported on various oxides
used to probe the activity of catalysts for reactionstaking place on metal sites. Moreover, this reactionis of practical interest as special attention has recentlybeen focused on the hydrogenation of aromaticcompounds and there is an increasing demand for suppressionof the benzene content in petroleum fuels andespecially in gasoline and diesel in the near future.The support used to disperse a metal has a significanteffect on the catalyst activity for hydrogenation ofbenzene. Various forms of interaction between activemetal and support materials in supported metal catalystshave been cited in the literature to explainexperimental observations. In cases where metal aggregatesare smaller than 1 nm and nearly molecular incharacter, interaction with the support can be strongerand more complex [17]. It has been observed that theactivity of very small metal clusters may be lowerin comparison to larger clusters [18]. Therefore, forthe hydrogenation of benzene, which is frequently regardedas a structure insensitive reaction on supportedmetals sites [6,19–22], there are some divergences,particularly in the case of small metal particles. Moreover,data indicating divergences from structure insensitivityhave appeared in several studies particularlyon nickel catalysts [23–25], but also on other metalsdeposited on various supports [4,18,26–28].Supported nickel catalysts are used for hydrogenationreactions of industrial interest, like hydrogenationof aromatics, organic synthesis and hardening of fats.The choice of nickel is mainly due to its availabilityand reasonable cost, compared to noble metals. Theindustrial catalysts very often contain high percentageof nickel supported on various oxides
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