Please do not adjust margins
RSC Advances
Page 6 of 8
DOI: 10.1039/C6RA17756E
Journal Name
ARTICLE
The recovery and reuse of the catalyst are important issues promoted hydrogenolysis of C-O by the interaction of Lewis
to evaluate a catalyst. The recyclability test results are shown acid and oxygen atom. The catalyst is tolerable to water and
in Fig. 6. All the experiments were performed under the same can maintain its structure after few circles. But the high
reaction conditions as described above. The catalyst was temperature can result in the aggregation of Pd particles, thus
washed with ethanol, and then heated at 80 °C under vacuum, lead to an activation declination. The present findings offer the
followed by reduction at 200 °C for 2 h under the atmosphere new opportunities in the development of bifunctional
of Ar : H2 = 2 : 1. It can be seen in Fig. 6, the conversion of Pd@MIL-101 catalyst, further optimization of the catalyst
anisole was obviously decreased after the first circle, and the preparation to obtain highly stabilized Pd particles to against
selectivity of CME had a significantly decrease but no decrease aggregation is underway.
of the CHN selectivity was observed.
To further study the recyclability of the Pd@MIL-101
Acknowledgements
catalyst, the used Pd@MIL-101 catalyst was further
characterized with XRD, N2 adsorption, TEM and Py-IR. As
shown in Fig. 1, there was no apparent loss of crystallinity in
XRD patterns after the reaction process, indicating that the
structure of MIL-101 remained intact and the catalyst is
tolerable to water generated form the dehydration of
cyclohexanol to cyclohexane. The N2 adsorption amount of the
used Pd@MIL-101 has virtually no change compared with the
freshly prepared catalyst, but a significant reduce in the
micropore area together with the substantially increased
external surface area were observed in Table 1, which is due to
partly damage of MIL-101 crystal structure. The TEM analysis
revealed that the size of Pd NPs increased, and the resulted
large Pd NPs were mainly located on the external surface of
We gratefully acknowledge the financial support provided by
the National Natural Science Foundation of China (21573031
and 21428301) and the Fundamental Research Funds for the
Central Universities (DUT15ZD106 and DUT15RC(4)09).
Notes and references
1. G. Ferey, Chem. Soc. Rev., 2008, 37, 191-214.
2. W. Qin, W. Cao, H. Liu, Z. Li and Y. Li, RSC Adv., 2014, 4, 2414-
2420.
3. J.-R. Li, R. J. Kuppler and H.-C. Zhou, Chem. Soc. Rev., 2009, 38
,
1477-1504.
4. A. Dhakshinamoorthy, M. Opanasenko, J. Cejka and H. Garcia,
Catal. Sci. Technol., 2013, , 2509-2540.
3
MIL-101 of the used catalyst.
A slight damage of the
5. J. Liu, W. Zhou, J. Liu, I. Howard, G. Kilibarda, S. Schlabach, D.
Coupry, M. Addicoat, S. Yoneda, Y. Tsutsui, T. Sakurai, S. Seki, Z.
Wang, P. Lindemann, E. Redel, T. Heine and C. Wöll, Angew.
Chem. Int. Ed., 2015, 54, 7441-7445.
6. J. Lee, O. K. Farha, J. Roberts, K. A. Scheidt, S. T. Nguyen and J. T.
Hupp, Chem. Soc. Rev., 2009, 38, 1450-1459.
octahedral structure of MIL-101 can well explain the N2
adsorption results with reduced internal and increased
external surface areas (Fig. 3). Based on Dhakshinamoorthy's
work8, the metal NPs are located within the MOF cavity rather
than diffuse outer surface due to size limitation to cross the
windows in tri-directional MOFs; whereas MOFs with a pore
system with channels are less appropriate candidates to act as
hosts because the NPs can freely move through the channel
and eventually can meet other NPs and grow further or
migrate to the external surface. In any case, some Pd particles
migrated to the surface during catalysis and formed larger
aggregates in the tri-directional MIL-101 at relatively high
temperature, which results in a reduction of hydrogenation
capacity toward unsaturated aromatic ring. The intensity of
characteristic band at 1451 cm-1 for Lewis acid center in the
used catalyst increased compared to the fresh catalyst, which
is attributed to the aggregation of Pd NPs and the re-exposing
of unsaturated chromium (III) sites (Fig. 4).
7. P. Silva, S. M. F. Vilela, J. P. C. Tome and F. A. Almeida Paz,
Chem. Soc. Rev., 2015, 44, 6774-6803.
8. A. Dhakshinamoorthy and H. Garcia, Chem. Soc. Rev., 2012, 41
,
5262-5284.
9. H. R. Moon, D.-W. Lim and M. P. Suh, Chem. Soc. Rev., 2013, 42
,
1807-1824.
10. F. Schröder, D. Esken, M. Cokoja, M. W. E. van den Berg, O. I.
Lebedev, G. Van Tendeloo, B. Walaszek, G. Buntkowsky, H.-H.
Limbach, B. Chaudret and R. A. Fischer, J. Am. Chem. Soc., 2008,
130, 6119-6130.
11. A. Aijaz, T. Akita, N. Tsumori and Q. Xu, J. Am. Chem. Soc., 2013,
135, 16356-16359.
12. L. Chen, H. Chen and Y. Li, Chem. Commun., 2014, 50, 14752-
14755.
13. A. Aijaz and Q. Xu, J. Phys. Chem. Lett., 2014,
14. M. Zhang, Y. Yang, C. Li, Q. Liu, C. T. Williams and C. Liang, Catal.
Sci. Technol., 2014, , 329-332.
5, 1400-1411.
4. Conclusions
4
15. S. Bhattacharjee, C. Chen and W.-S. Ahn, RSC Adv., 2014, 4,
The embedding of palladium nanoparticles into the acidic
metal-organic framework MIL-101 has been successfully
prepared by a sol-gel method. The combination of the MIL-101
(as Lewis acid catalytic sites) and Pd NPs (as hydrogenation
catalyst sites) afford an interesting bifunctional catalyst with a
very high BET surface area and huge pore volume. The TEM
52500-52525.
16. G. Férey, C. Mellot-Draznieks, C. Serre, F. Millange, J. Dutour, S.
Surblé and I. Margiolaki, Science, 2005, 309, 2040-2042.
17. Y. K. Hwang, D.-Y. Hong, J.-S. Chang, S. H. Jhung, Y.-K. Seo, J.
Kim, A. Vimont, M. Daturi, C. Serre and G. Férey, Angew. Chem.
Int. Ed., 2008, 47, 4144-4148.
images showed that Pd particles were well dispersed in MIL- 18. Y. K. Hwang, D.-Y. Hong, J.-S. Chang, H. Seo, M. Yoon, J. Kim, S.
H. Jhung, C. Serre and G. Férey, Appl. Catal. A., 2009, 358, 249-
253.
101 with size of 2 - 3.5 nm. The Pd@MIL-101 catalyst can
efficiently catalyze the HDO of anisole with excellent
hydrogenation activity toward aromatic compounds and
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 6
Please do not adjust margins