8 R. D. Srivastava, S. V. Gollakota, G. J. Stiegel and A. C. Bose, Methane
and Alkane Conversion Chemistry, Plenum, New York, 1995, p. 291.
9 J. S. J. Hargreaves, G. J. Hutchings, R. W. Joyner and S. H. Taylor,
Chem. Commun., 1996, 523.
10 C. Shi, Q. Sun, H. Hu, R. G. Herman, K. Klier and I. E. Wachs, Chem.
Commun., 1996, 663.
No selective oxidation proceeded in the absence of Pd or
when carbon monoxide was used instead of hydrogen. The
addition of 1.9 vol% hydrogen peroxide instead of a gaseous
mixture of H2 and O2 led to similar conversion and selectivity to
oxygenates. This suggests that the active oxygen species arises
from hydrogen peroxide formed by an H2–O2 reaction catalysed
by Pd. Reports that Pd in acidic medium catalyses the reaction
of dioxygen with dihydrogen to form hydrogen peroxide,25 and
the fact that heterpolyacids and their caesium salts are strongly
acidic26 supports this hypothesis. Formic acid is formed by the
liquid-phase oxidation of methane with hydrogen peroxide
catalysed by H4PVMo11O40;27 this suggests that successive
oxidation of methane via hydrogen peroxide can be catalysed by
heteropolyacids.
11 M. Faraldos, M. A. Banares, J. A. Anderson, H. Hu, I. E. Wachs and
J. L. G. Fierro, J. Catal., 1996, 160, 214.
12 C. T. Au, H. He, S. Y. Lai and C. F. Ng, J. Catal., 1996, 163, 399.
13 Y. S. Lin and Y. Zeng, J. Catal., 1996, 164, 220.
14 P. M. Witt and L. D. Schmidt, J. Catal., 1996, 163, 465.
15 Y. Wang and K. Otsuka, J. Catal., 1995, 155, 256.
16 W. Li and S. T. Oyama, Heterogeneous Hydrocarbon Oxidation, ACS,
Washington, 1996, p. 364.
17 M. A. Banares, L. A. Alemany, F. M.-Jimenez, J. M. Blasco,
M. L. Granados, M. A. Pena and J. L. G. Fierro, Heterogeneous
Hydrocarbon Oxidation, ACS, Washington, 1996, p. 78.
18 N. Basickes, T. E. Hogan and A. Sen, J. Am. Chem. Soc., 1996, 118,
13111.
This work was supported in part by a Grant-in-Aid for
Scientific Research from the Ministry of Education, Science,
Sports and Culture of Japan.
19 Y. Fujiwara, K. Takai and Y. Taniguchi, Chem. Lett., 1996, 591.
20 A. Bagno, H. Bukala and G. A. Olah, J. Org. Chem., 1990, 55, 4284.
21 N. Mizuno, D.-J. Suh, W. Han and T. Kudo, J. Mol. Catal. A: Chem.,
1996, 114, 309; N. Mizuno, D.-J. Suh, W. Han, T. Kudo and
M. Iwamoto, Stud. Surf. Sci. Catal. B, 1996, 101, 1001.
22 S. Murahashi, Y. Oda and T. Naota, J. Am. Chem. Soc., 1992, 114,
7913.
23 M. T. Atlay, M. Preece, G. Strukal and B. R. James, J. Chem. Soc.,
Chem. Commun., 1982, 406.
24 I. Yamanaka, M. Soma and K. Otsuka, J. Chem. Soc., Chem. Commun.,
1995, 2235.
25 Y. Izumi, H. Miyazaki and S. Kawahara, Jpn. Pat., 47121, 1981;
G. L. Wayne, Eur. Pat., 132294, 1983.
26 T. Okuhara, N. Mizuno and M. Misono, Adv. Catal., 1996, 41, 113.
27 Y. Seki, N. Mizuno and M. Misono, 72th Symposium of the Chemical
Society of Japan, Tokyo, March, 1997, 1D237.
Footnote
* E-mail: tmizuno@hongo.ecc.u-tokyo.ac.jp
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Received in Cambridge, UK, 14th April 1997; Com. 7/02514I
1296
Chem. Commun., 1997