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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 15, Number 12
BKCSDE 15(12)
December 20, 1994 

 
Title
Effect of Mn-addition on Catalytic Activity of Mn/In2O3 in Methane Activation
Author
Jong Sik Park, Jong Ho Jun, Yong Rok Kim, Sung Han Lee*
Keywords
Abstract
Mn/In2O3 systems with a variety of Mn mol% were prepared to investigate the effect of Mn-addition on the catalytic activity of Mn/In2O3 in the oxidative coupling of methane. The oxidative coupling of methane was examined on pure In2O3 and Mn/In2O3 catalysts by cofeeding gaseous methane and oxygen under atmospheric pressure between 650 and 830 ℃. Although pure In2O3 showed no C2 selectivity, both the C2 yield and the C2 selectivity were increased by Mn-doping. The 5.1 mol% Mn-doped In2O3 catalyst showed the best C2 yield of 2.6% with a selectivity of 19.1%. The electrical conductivities of pure and Mn-doped In2O3 systems were measured in the temperature range of 25 to 100 ℃ at PO2'S of 1 × 10-7 to 1 × 10 -1 atm. The electrical conductivities were decreased with increasing Mn mol% and PO2, indicating the specimens to be n-type semiconductors. Electrons serve as the carriers and manganese can act as an electron acceptor in the specimens. Manganese ions doped in In2O3 inhibit the ionization of neutral interstitial indium or the transfer of lattice indium to interstitial sites and increase the formation of oxygen vacancy, giving rise to the increase of the concentration of active oxygen ion on the surface. It is suggested that the active oxygen species adsorbed on oxygen vacancies are responsible for the activation of methane.
Page
1058 - 1064
Full Text
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