Res. Chem. Intermed.
, Vol. 34, Nos 5–7, pp. 603–615 (2008)
Koninklijke Brill NV, Leiden, 2008.
Also available online - www.brill.nl/rci
Liquid-phase hydrogenation of alkenes and aromatic
compounds with Pd-loaded oxidized diamond catalyst
, TOMONARI KIYOMI, ITARU YONEZAWA,
CHIEKO YUKAWA and TOSHIMITSU SUZUKI
Department of Chemical Engineering, Kansai University, 3-3-35 Yamate, Suita,
Osaka 564-8680, Japan
Received 6 January 2007; accepted 24 January 2007
Abstract—Hydrogenation reactions of alkenes (cyclohexene, ethyl acrylate, styrene and 1,5-cyclo-
octadiene) and aromatic compounds (o-, m-andp-xylene) were carried out in order to examine the
activity of palladium-loaded surface-oxidized diamond (Pd/O-Dia) catalyst in liquid-phase hydro-
genation. The catalytic performance was compared to commercial palladium-loaded activated carbon
(Pd/C) catalyst. The catalyst activities were evaluated by conversions of reactants and H
rates in the early stage of the reaction. In all the hydrogenation reactions of alkenes and aromatic
compounds, the activity of Pd/O-Dia was almost the same as or slightly higher than that of Pd/C.
Dispersion of Pd metal was measured by a CO-pulsed adsorption technique and TEM observations of
the catalysts. Pd dispersions were on the same order of magnitude according to the CO-pulsed adsorp-
tion technique, although the Pd/C catalyst had a higher surface area (718 m
/g) than that of Pd/O-Dia
/g). The Pd particle sizes on O-Dia measured by TEM observation were slightly smaller than
those on the activated carbon. Such highly dispersed Pd particles on O-Dia would contribute to higher
activity for the hydrogenation reaction of alkenes and aromatic compounds.
Keywords: Oxidized diamond; palladium; hydrogenation; alkene; aromatic compound.
Palladium carbon is well known as a hydrogenation catalyst and has been commer-
cially available from different reagent sources [1, 2]. Until now, a large number of
investigations on palladium loaded catalysts have been carried out using different
support materials such as SiO
 and α-Al
. Panpranot et al. have carried out liquid-phase hydrogenation of 1-hexene us-
ing a series of silica (SiO
and MCM-41)-supported palladium catalyst and have
suggested that deactivation of the catalyst is dependent on the palladium particle
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