EHMO Studies of Chemisorbed Dioxygen Species on Na_2O and K_2O and of Their Interaction with CH_4 and CH_3-Radical |
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基金项目: | Supported by the National Natural Science Foundation of China. |
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摘 要: | EHMOStudiesofChemisorbedDioxygenSpeciesonNa_2OandK_2OandofTheirInteractionwithCH_4andCH_3-RadicalSUQiao-Juan,ZHANGHong-bin,ZH...
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收稿时间: | 1994-01-14 |
EHMO Studies of Chemisorbed Dioxygen Specieson Na_2O and K_2O and of Their Interactionwith CH_4 and CH_3-Radical |
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Authors: | SU Qiao-Juan ZHANG Hong-bin ZHOU Tai-jin LIU Yu-da LIN Guo-dong TSAI Khi-rui |
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Institution: | Dept. of Chemistry &. State Key Laboratory for Phys. Chemistry ofthe Solid Surface, Xiarnen Univ., Xianien, 361005 |
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Abstract: | With an improved EHMOmethod, three modes (flat-lying, vertical, and in-clined insertion) for adsorption and activation of dioxygen on (100), (110) and(111) surfaces of Na2Oand of K,Ohave been exaniinecl, and the interaction ofthese dioxygen adspecies with CH4 and with CH3·(radical) from gas pliase liasbeen investigated.The results indicate that both oxides tend to forni less cliargedadspecies of dioxygen, with the flat-lying adsorption on (110) surface most favor-able energetically.All these cliemisorbed dioxygen species are capable of interactingeffectively with CH4 and Abstract ing one hydrogen atom from the CH4 molecule andtheir tendencies to reassociate with CH3 ·, which would easily lead to deep oxida-tion of the fragments of hydrocarbons, are enhanced with inereasing negativecliarges on them.In comparison with Na2O, K2Ohas a little stronger tendency tostabilize less charged dioxygen adspecies; this has a close relation with the knownexperimental fact that K+ showed better promoting effect than Na+ in improving C2-selectivity in methane oxidative coupling (MOC ). |
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Keywords: | Chemisorbed dioxygen species Methane oxidative coupling EHMOapproach |
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