ISSN 0965ꢀ5441, Petroleum Chemistry, 2012, Vol. 52, No. 5, pp. 299–304. © Pleiades Publishing, Ltd., 2012.
Original Russian Text © N.A. Magdalinova, P.A. Kalmykov, M.V. Klyuev, 2012, published in Neftekhimiya, 2012, Vol. 52, No. 5, pp. 333–338.
PalladiumꢀContaining Nanodiamonds in Hydrogenation
and Hydroamination
N. A. Magdalinova, P. A. Kalmykov, and M. V. Klyuev
Ivanovo State University, Ivanovo, Russia
eꢀmail: mn2408@mail.ru, klyuev@inbox.ru
Received February 1, 2012
Abstract—Palladium catalysts in the form of Pd nanoparticles supported on nanodiamonds have been studꢀ
ied in the hydrogenation of nitrobenzene, allyl alcohol, and cyclohexene and in the hydrogenating amination
2+
0
of propanal with 4ꢀaminobenzoic acid. The ratio of two valence states of palladium, i.e., Pd and Pd , in the
catalysts has been determined by XPS. The dependence of hydrogenation reaction rate on electron density at
the reaction site of nitrobenzene, allyl alcohol, cyclohexene, and 4ꢀ(propylideneamino)benzoic acid moleꢀ
cules has been studied using quantum chemical calculations (HF/6ꢀ31G, PCM).
DOI: 10.1134/S0965544112050064
Palladium catalysts are extensively used in various
chemical and petrochemical processes. Commercially
available products are activated carbons that contain a
certain amount of palladium. Carbon nanomaterials
EXPERIMENTAL
The synthesis of Pdꢀcontaining NDs was carried
out according to the procedure described in [15]. Detꢀ
onation NDs with a specific surface area of 307–
(
CNMs) have been recently used as supports:
2 –1
3
14 m g (the average size of the crystalline diamond
fullerenes and fullerene black [1, 2], carbon nanotubes
and nanofibers [1, 3, 4], nanodiamonds (NDs) [3, 5–
9
nucleus of ND particles is about 4 nm) and a total
noncarbon impurity concentration of no more than
], etc.; they significantly improve the catalyst characꢀ 0.5 wt %. The synthesized Pd/ND samples were mixed
teristics, such as activity, selectivity, and stability; in with activated carbon in a ratio of 180 to 820 mg (a
addition, the nature and sizes of metal centers, as well total weight of 1 g).
as their accessibility to the molecules of converted
The composition of the Pd/ND samples was deterꢀ
compounds, are largely determined by the nature of mined by Xꢀray microanalysis, and the specific surface
the support [1, 3, 4].
area was found by the BET method. The local Xꢀray
microanalysis was carried out using a VEGA TS
Catalysts based on NDs are of particular interest. It
was shown in [10, 11] that the use of NDs as a support
for platinum group metals gives the possibility to
obtain clusters of platinum and palladium with a
diameter of 5 nm and a thickness of 0.4–1.2 nm. This
5
130MM fully PCꢀcontrolled scanning electron
microscope ((CamScan MV2300)TP1PT) equipped
with secondary electron (SE) and backscatter electron
(
BSE) detectors of YAGꢀcrystals and an energy disꢀ
persive Xꢀray (EDX) microanalyzer with an INCA
is attributed to the fact that the surface carbon atoms Energy2 semiconducting Si(Li) detector. The compuꢀ
in NDs have uncompensated bonds [12–15], which tation of the Xꢀray microanalysis data was performed
provide the homogeneity of metal centers and thus the using the INCA Energy 200 software with the subseꢀ
maximum catalytically active surface area required for quent recalculation of the results using the TP3PT
the adsorption of chemical agents, the occurrence of software package developed at the Institute of Experiꢀ
mental Mineralogy, Russian Academy of Sciences.
The studies were carried out at an accelerating voltage
of 20 kV. The absorbed electron current was 516–
the reaction, and the desorption of the product. The
more homogeneous the metal centers in the catalyst,
the more selective they are.
565 pA on the reference cobalt sample and 540–
20 pA on the sample under study. The size of the elecꢀ
We previously showed [3] that Ptꢀ and PdꢀNDs are
6
more active and effective in catalytic liquidꢀphase tron probe on the sample surface was 157–200 nm.
hydrogenation than other metalꢀcontaining CNMs. Titanium and chlorine impurities made no more than
In this study, we have analyzed the catalytic properties 0.3 and 0.1 wt %, respectively. The ash content of the
of Pd/NDs in the hydrogenation of nitrobenzene, allyl original ND was more than 2 wt %.
alcohol, and cyclohexene and in the hydrogenating
amination of propanal with 4ꢀaminobenzoic acid.
The analysis of the catalyst by Xꢀray photoelectron
spectroscopy (XPS) was performed using
a
299