1
7872 J. Phys. Chem., Vol. 100, No. 45, 1996
Mar u´ n et al.
material, and cavities in series and in parallel on the product
distribution of the oligomerization of methane via microwave
plasmas.
In order to favor the oligomerization of methane to higher
hydrocarbons, different dielectric materials were placed in the
reactor in contact with the plasma zone. However, for the
oligomerization of methane via microwave plasmas we did not
observe a significant effect on the product distributions and
(20) Tse, M. Y.; Depew, M. C.; Wan, J. K. S. Res. Chem. Intermed.
990, 13, 221-236.
1
1
1
1
(21) Cameron, K. L.; Depew, M. C.; Wan, J. K. S. Res. Chem. Intermed.
991, 16, 57-70.
(22) Bamwenda, G.; Moore, E.; Wan, J. K. S. Res. Chem. Intermed.
992, 17, 243-262.
(23) Bamwenda, G.; Depew, M. C.; Wan, J. K. S. Res. Chem. Intermed.
993, 19, 553-564.
(24) Ioffe, M. S.; Pollington, S. D.; Wan, J. K. S. J. Catal. 1995, 151,
349-355.
(
(
25) Huang, J.; Suib, S. L. J. Phys. Chem. 1993, 97 (37), 9403-9407.
26) Huang, J.; Suib, S. L. Res. Chem. Intermed. 1994, 20 (1), 133-
activities as has been reported before in the literature for
microwave-heated systems.2
0-24,36-41
In some cases (MnO2,
1
39.
(27) Suib, S. L.; Zerger, R. P.; Zhang, Z. Proceedings, Symposium on
Natural Gas Upgrading II; American Chemical Society: Washington, DC,
992; Petroleum Chem., p 344.
28) Suib, S. L.; Zerger, R. P. J. Catal. 1993, 139, 383-391.
(29) Huang, J.; Badani, M. V.; Suib, S. L.; Harrinson, J. B.; Kablauoi,
M. J. Phys. Chem. 1994, 98 (1), 206-210.
30) CRC Handbook of Chemistry and Physics, 73rd ed.; Lide, D. R.,
Ed.; CRC Press, Inc.: Boca Raton, FL, 1992-1993.
31) The conversion is calculated as follows:
TiO2, Li2CO3, and SnO2) the selectivities toward C6s to C8s were
enhanced, but no direct correlation between the dielectric
constant and the product distribution was found. How the
dielectric material is placed in the plasma zone seems to affect
the selectivities toward higher hydrocarbons.
Cavities in series with a large separation and with a dielectric
material in between optimize the oligomerization of methane
toward C6s to C8s with traces of C9s formed during reaction.
Compression and expansion effects do not influence the product
distribution. Finally, cavities in parallel may favor the oligo-
merization of methane and lead to enhanced conversion.
1
(
(
(
XCH4 ) (C - C
)/CT
CH exit
4
T
where C is the sum of the concentration of each compound (C ) multiplied
T
i
by the number of carbons present in the molecule i (ni), i.e.:
Acknowledgment. We thank the National Science Founda-
tion, EPRI under Grant CTS-9413394 of the joint NSF/EPRI
Initiative on Microwave-Induced Reactions, and Texaco, Inc.
for providing support for this work.
C )
∑niCi
T
The selectivities toward compounds with number of carbons i (S ) was
i
calculated by
References and Notes
Si ) (∑
n C )/(C - C
)
i
i
T
CH exit
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