P.R. Makgwane, S.S. Ray / Journal of Molecular Catalysis A: Chemical 373 (2013) 1–11
11
References
[1] A.K. Suresh, M.M. Sharm, T. Sridhar, Ind. Chem. Eng. Res. 39 (2000) 3958–3997.
[2] R.A. Sheldon, J.K. Kochi, Metal-catalyzed Oxidation of Organic Compounds, Aca-
demic Press, New York, 1981;
H. Fiege, Cresols and Xylenols Ullmann’s Encyclopedia of Industrial Chemistry,
A8, VCH Verlagsgeselleschaft, 1991, pp. 25.
[3] Y. Ikeda, M. Hazama, N. Kawara, M. Okumura, T. Ito, Process for treatment of
hydroperoxide mixture, US Patent 5,639,922.
[4] K. Nair, D.P. Sawant, G.V. Shanbhag, S.B. Halligudi, Catal. Commun. 5 (2004)
9–13.
[5] K.K. Tiwari, S. Banerjee, B.P. Das, U.C. Dumka, Fuel Process. Technol. 86 (2004)
13–21.
b
a
[6] F. Vaudano, P. Tissot, Electrochim. Acta 46 (2001) 875–880.
[7] S. Vetrivel, A. Pandurangan, J. Mol. Catal. A: Chem. 246 (2006) 223–230.
[8] P.R. Makgwane, E.E. Ferg, B. Zeelie, ChemCatChem 3 (2011) 3180–3188.
[9] P.R. Makgwane, E.E. Ferg, D.G.W. Billing, B. Zeelie, Catal. Lett. 135 (2010)
105–113.
[10] G.S. Serif, C.F. Hunt, A.N. Bourns, Can. J. Chem. 31 (1953) 1229–1239.
[11] R.D. Adams, E. Trufan, Phil. Trans. R. Soc. A 368 (2010) 1473–1493.
[12] N. Hamzah, N.H. Nordin, A.H.A. Nadzri, Y.A. Nik, M.B. Kassim, M.A. Yarmo, Appl.
Catal. A: Gen. 419–420 (2012) 133–141.
15
25
35
45
55
65
75
85
2θ/degree
Fig. 11. XRD analysis of 3%Ru/CNF (a) before and (b) after 5 cycles re-uses.
[13] A. Fihri, M. Bouhrara, U. Patil, D. Cha, Y. Saih, V. Polshwttiwar, ACS Catal. 2
(2012) 1425–1431.
[14] J. Assmann, V. Narkhede, N.A. Breuer, M. Muhler, A.P. Seitsonen, M. Knapp, D.
Crihan, A. Farkas, G. Mellau, H.J. Over, Phys. Condens. Matter 20 (2008) 184017.
[15] K. Wada, S. Hosokawa, M. Inoue, Catal. Surv. Asia 15 (2011) 1–11.
[16] Y. Na, S. Park, S.H. Bong, H. Han, S. Ko, S. Chang, J. Am. Chem. Soc. 126 (2004)
250–258.
[17] Y. Park, Y.J. Lee, P.R. Karandikar, K.W. Jun, J.W. Bae, K.S. Ha, J. Mol. Catal. A:
Chem. 344 (2011) 153–160.
[18] W.P. Griffith, in: C. Bianchini, D.J. Cole-Hamilton, P.W.N.M. van Leeuwen (Eds.),
Ruthenium Oxidation Complexes: Their Uses as Homogenous Organic Cata-
lysts, Springer, 2010, ISBN: 978-1-4020-9376-0.
4. Conclusions
In this paper, the catalytic activity of Ru catalysts supported on
CNFs was investigated in the liquid-phase oxidation of p-cymene.
The activity of the Ru catalysts was influenced by the metal load-
ings. A p-cymene conversion of 55% with 33% selectivity toward
TCHP and 42% toward PCHP as the predominant major products
was obtained within 5 h reaction time using the 3%Ru–CNF cata-
lyst. The conversion achieved with this catalyst was better than
the 3% conversion achieved in the non-catalyzed reaction The per-
formance of the Ru/CNF catalysts using molecular oxygen as the
terminal oxidant offers promising results for the possible use of Ru
metal as a nano-catalyst for C H bond activation of alkyl aromatic
hydrocarbons into value-added oxygenates. The results indicated
that the particles size of Ru is not the primary deciding factor in
the observed Ru catalytic performance toward p-cymene conver-
sion or in the product selectivity; instead, the interplay of metal
loadings, the reducibility, the different possible Ru species and the
reaction conditions (i.e., the type of initiator, which is critical for
reaction chain initiation) were the predominant factors. Moreover,
in the absence of a radical-initiator substrate, the direct activa-
tion of the C H bond of p-cymene was slow, whereas the addition
of a small amount of initiator (i.e., TBHP) significantly improved
the Ru activity toward C H activation. Finally, the Ru/CNF cat-
alyst was highly reusable without any loss of activity under the
studied reaction conditions. The extended substrate scope applica-
tion of Ru/CNF catalyst was successfully proven active for oxidation
of other selected alkyl-substituted aromatic hydrocarbons such as
cumene and styrene. These results provide the basis for further
Ru catalyst development in the activation of C H bonds for the
oxidation of aromatic hydrocarbons in the liquid phase.
[19] H. Over, Chem. Rev. 112 (2012) 3356–3426.
[20] J.P. Hofmann, S. Zweidinger, M. Knapp, A.P. Seitsonen, K. Schulte, E. Lundgren,
J.N. Andersen, H. Over, J. Phys. Chem. C 144 (2010) 10901–10909.
[21] S. Zweidinger, J.P. Hofmann, O. Balmes, E. Lundgren, H. Over, J. Catal. 272 (2010)
169–175.
[22] S. Zweidinger, D. Crihan, M. Knapp, J.P. Hofmann, A.P. Seitsonen, C.J. West-
strate, E. Lundgren, J.N. Andersen, H. Over, J. Phys. Chem.
9966–9969.
C 112 (2008)
[23] D. Uzio, G. Berhault, Catal. Rev. Sci. Eng. 52 (2010) 106–131.
[24] J.M. Campelo, D. Luna, R. Luque, J.M. Marinas, A.A. Romero, ChemSusChem 2
(2009) 18–45.
[25] Y. Li, L. Yao, Y. Song, S. Liu, J. Zhao, W. Ji, C.T. Au, Chem. Commun. 46 (2010)
5298–5300.
[26] X. Chen, H. Zou, S. Chen, X. Dong, W. Lin, J. Nat. Gas Chem. 16 (2007)
409–414.
[27] C. Elmasides, D.I. Kondarides, S.G. Neophytides, X.E. Verykios, J. Catal. 198
(2001) 195–207.
[28] C. Zupanc, A. Hornung, O. Hinrichsen, M. Muhler, J. Catal. 209 (2002) 501–514.
[29] H. Miura, K. Wada, S. Hosokawa, M. Sai, T. Kondo, M. Inoue, Chem. Commun.
(2009) 4112–4114.
[30] W. Zheng, J. Zhang, B. Zhu, R. Blume, Y. Zhang, K. Schlichte, R. Schlögl, F. Schüth,
D. Su, ChemSusChem 3 (2010) 226–230.
[31] D. Widmann, Y. Liu, F. Schüth, R.J. Behm, J. Catal. 276 (2010) 292–305.
[32] Y. Xu, J. Ma, Y. Xu, H. Li, H. Li, P. Li, X. Zhou, Adv. Mater. Res. 347–353 (2012)
3298–3301.
[33] W. Sutthisripok, S. Sattayanurak, L. Sikong, J. Porous Mater. 15 (2008) 519–525.
[34] K.P. De Jong, J.W. Geus, Catal. Rev. Sci. Eng. 42 (2000) 481–510.
[35] N.M. de Almeida Coelhoa, J.L.B. Furtadoa, C. Pham-Huub, R. Vieira, Mater. Res.
11 (2008) 353–357.
[36] H. Yu, F. Peng, J. Tan, X. Hu, H. Wang, J. Yang, W. Zheng, Angew. Chem. Int. Ed.
50 (2011) 3978–3982.
[37] I. Hermans, J. Peeters, P.A. Jacobs, J. Org. Chem. 72 (2007) 3057–3064.
[38] I. Hermans, T. Nguyen, P.A. Jacobs, J. Peeters, ChemPhysChem
637–645.
6 (2005)
Acknowledgments
[39] I. Hermans, P.A. Jacobs, J. Peeters, Chem. Eur. J. 12 (2006) 4229–4240.
The authors would like to express their gratitude to the Univer-
sity of Johannesburg and the National Research Foundation (NRF) of
South Africa for the financial support. The DST/CSIR National Cen-
tre for Nano-structured Materials is thanked for providing with the
research equipment to perform this work.
[40] P.R. Makgwane, N.I. Harmse, E.E. Ferg, B. Zeelie, Chem. Eng. J. 162 (2010)
341–349.
[41] L. Ci, H. Zhu, B. Wei, C. Xu, J. Liang, D. Wu, Mater. Lett. 43 (2000) 291–294.
[42] N. Weinstock, H. Schulze, A. Müller, J. Appl. Phys. 59 (1973) 5063–5067.
[43] A. Satsuma, M. Yanagihara, J. Ohyama, K. Shimizu, Catal. Today 201 (2013)
62–67.