Quantum Chemical Study of the Catalytic Oxidative Coupling of Methane
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- 作者：Isik Onal and Selim Senkan
- 刊名：Industrial & Engineering Chemistry Research
- 出版年：1997
- 出版时间：October 1997
- 年：1997
- 卷：36
- 期：10
- 页码：4028 - 4032
- 全文大小：102K
- 年卷期：v.36,no.10(October 1997)
- ISSN：1520-5045
文摘
Oxidative coupling of methane reaction pathways on MgOand lithium-modified MgO weretheoretically studied using the semiempirical MNDO-PM3 molecularorbital method. The surfaceof the MgO catalyst was modeled by a Mg9O9molecular cluster containing structural defectssuch as edges and corners. Lithium-promoted magnesia was simulatedby isomorphic substitution of Mg2+ by Li+; the excess negativecharge of the cluster was compensated by a protonconnected to a neighboring O2- site.Heterolytic adsorption of methane was found to bedirectlyrelated to the coordination number of both the lattice oxygen and themetal sites. Energeticallythe most favorable site pair was Mg3c-O3cwith a neighboring Li4c site present.Varioussequential oxygen and methane adsorption pathways were exploredresulting in CH3OHformation with lower energy barriers for the Li-modified MgO cluster ascompared to unmodifiedMgO.