Photon Factory Activity Report 2014 #32 (2015) B

BL-9A, AR-NW10A/2014G014

Structural characterization of coprecipitated Pd/Co and Pd/Fe catalysts for theselective hydrogenolysis of C-O bond in biomass derived compounds
Francesco Mauriello,1,* Hiroko Ariga,2 Rosario Pietropaolo,1 Satoru Takakusagi,2 Kiyotaka Asakura2,*
1
Dipartimento DICEAM, Università Mediterranea di Reggio Calabria, Loc. Feo di Vito, I-89122
Reggio Calabria, Italy
2Catalysis Research Center, Hokkaido University, Kita-ku N21W10, Sapporo, Hokkaido 001-0021,
Japan
1 Introduction
One of the central challenges in biomass utilization isthe catalytic, selective deoxygenation of polysaccharides,
lignin, lipids, and their derivatives. Hence, the C-O bondhydrogenolysis is of particular significance since it allows
the production of certain high value chemicals frombiomass derived intermediate compounds (e.g. glycerol,sorbitol, furfural, aryl ethers, etc). [1]Heterogeneous palladium catalysts were found to bepoorly efficient in the hydrogenolysis of biomass derived
polyols. [2, 3] However, in the last years, coprecipitated
Pd/Co and Pd/Fe catalysts have been investigated for theirsuperior performance in several catalytic reactions
including the hydrogenolysis [4, 5] and the transferhydrogenolysis (CTH) of glycerol. The enhanced
catalytic performance shown by Pd/Co and Pd/Fe
catalysts can be related to the preparation method used
(coprecipitation technique) that ensures a strong metal
support interaction (SMSI) between palladium and thecobalt/iron oxide support.
In the present study we show the results of EXAFS
analysis on Pd/Co and Pd/Fe catalysts that clearly show
the formation of bimetallic Pd-Co and Pd-Fe ensambles
that positively promote the C-O bond cleavage.

EXAFS data was performed using the EXAFS analysis
program, REX (Rigaku Co.).
3 Results and Discussion
The extended X-ray absorption fine structure results at
Co-K and Fe-K edge show the Co3O4 and Fe3O4 support
structure of Pd/Co and Pd/Fe samples in agreement with
XRD and H2-TPR analysis that shows a strong promoting
effect of palladium on cobalt oxide and iron oxide
reduction.
Table 1 reports the main results of extended X-rayabsorption fine structure (EXAFS) characterization at thePd K-edge. In both Pd/Co and Pd/Fe catalysts, the moststriking feature is the direct observation of a shorter
scattering Pd-Co and Pd-Fe paths of 2.51 Å comparedwith the Pd–Pd distance of about 2.70 Å confirming theformation of Pd-Co and Pd-Fe bimetallic ensables.
Table 1: X-ray absorption fine structure characterization
at the Pd K-edge for Pd/Co and Pd/Fe catalysts.
SamplePd/Co
Pd/Fe

2 Experiment
Pd/Co and Pd/Fe catalysts were prepared by using thecoprecipitation technique and were obtained from
aqueous solutions of the corresponding inorganicprecursors. Anhydrous palladium chloride (Fluka, purum,60% palladium) was dissolved in HCl and cobalt(II)nitrate hexahydrate (Fluka, purity ≥99%) or iron(III)nitrate nonahydrate (Fluka, purity ≥98%) were added.
The obtained aqueous metal salt solutions were added
dropwise into a 1 M aqueous solution of Na2CO3. After
filtration, samples were washed until complete removal ofchloride ions, dried for 1 day at 353 K under vacuum andfurther reduced at 473 K for 2 h under a flow of H2.
Extended X-ray absorption fine structure (EXAFS) ofthe Pd-based catalysts were measured at the Photon
Factory of the High Energy Accelerator Research
Organization. Co-K and Fe-K edge XANES/EXAFS
spectra for the catalysts were obtained using a Si(111)
two-crystal monochromator with beam line BL9A and Pd
K-edge spectra were obtained using a Si(311) two-crystal
monochromator with beam line NW10A. Analysis of theScattering
Pair
Pd-Pd
Pd-Co
Pd-Pd
Pd-Fe

CN
0,93
3,92
2,59
0,78

BD(Å )
2,69
2,51
2,71
2,51dE(eV)-5,81
1,2-4,7-3,7dW(Å2)
0,021
0,0470,91

R(%)
0,020,02

Acknowledgement
The financial support by Catalysis Research Center,
Hokkaido University (Overseas Research Fellow 2013)
and MIUR (PRIN2010 – 2010KHLKFC 001) aregratefully acknowledged.
References[1] P. Gallezot, Chem. Soc. Rev. 41, 1538 (2012).
[2] Y. Nakagawa and K. Tomishige, Catal. Sci. Technol.
1, 179 (2011).
[3] A. M. Ruppert, K. Weinberg and R. Palkovits,Angew. Chem. Int. Ed. 51, 2564 (2012).
[4] M.G. Musolino, L.A. Scarpino, F. Mauriello and R.
Pietropaolo, ChemSusChem. 4, 1143 (2011).
[5] F. Mauriello, H. Ariga, M. G. Musolino, R.
Pietropaolo, S. Takakusagi and K. Asakura, Appl.
Catal. B: Environment. 166–167, 121 (2015).
* francesco.mauriello@unirc.it (Francesco Mauriello),
askr@cat.hokudai.ac.jp (Kiyotaka Asakura).