Photoemission study of the subsequential oxidation of dissociatively adsorbed methane on an SnO2 thin film

Kawabe, Takasahi; Tabata, Kenji; Suzuki, Eiji; Yamaguchi, Yoichi; Nagasawa, Y.

doi:10.1002/1096-9918(200011)29:11<791::aid-sia932>3.0.co;2-n

Cited by 4 publications

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“…We have also studied this subject using LiNbO 3 and SnO 2 catalysts, aiming for a one-step reaction at a lower temperature (≈300-400 K) and pressure (1 atm) than the commercial process, and have detected components containing Othat are similar to those of the other catalysts. [3][4][5][6] It has been confirmed that Oworks as a high active center for the hydrogen abstraction from methane on the metal-oxide catalysts [7][8][9][10][11][12][13][14][15][16][17] and also pointed out that the slow desorption of C 1 -oxygenates from the surface of a catalyst brings about successive oxidation to yield CO and CO 2 . 18,19 We have found theoretically that C 1 -oxygenates are easily oxidized by Oand their anionic species are stabilized on the SnO 2 catalyst, which lead to the difficulty of the desorption from the catalyst to the gas phase.…”

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confidence: 99%

Ab Initio Study for Selective Oxidation of Methane with NO_x(x= 1, 2)

et al. 1999

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A reaction model for the conversion of methane to C1-oxygenates (methanol and formaldehyde) with NO x (x = 1, 2) has been proposed theoretically using the ab initio molecular orbital method. The geometric and electronic structures for all the present molecules have been calculated by means of the MP2 (frozen core)/6-311++G(2d,p) level of theory. On the basis of the optimized structures, the single point calculations of the energies are carried out at the CCSD(T) level with the same basis sets. Through the theoretical analysis of the simplified CH4−NO x system instead of the experimental CH4−O2−NO system, we found the possible reaction path leading to C1-oxygenates within all the barriers of less than 40 kcal/mol via CH3O at 800 K. NO2 has a higher activity for the hydrogen abstraction from methane than NO and O2, though the calculated rate constants at 800 K indicate that this reaction is the rate-determining step in the conversion of methane to C1-oxygenates. It is also found that increasing the concentration of NO promotes the yield of formaldehyde with the decreasing formation of methanol, which is consistent with recent experimental results in the CH4−O2−NO system.

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