Methane activation by metals and semiconductors: molecular orbital theory. Annual report, September 1986-August 1987
A predictive molecular-orbital theoretical study of CH/sub 4/ activation on coordinatively unsaturated transition-metal centers shows high activity for the metal surfaces studied, (100) and (110) and rough (100) Fe, (100) and (111) Ni, and (111) Pt; the more-open surfaces are more reactive because the surface atoms have fewer coordination neighbors. This allows a surface atom greater flexibility for stabilizing C...H...M and C...M bonding orbitals as the metal atom inserts into the CH bond. A 4-coordinate Mo IV cation on the edge of a MoS/sub 2/ crystal is predicted to easily activate CH/sub 4/ by inserting into a CH bond. Initial products are oxidative homolytic but H will shift to S(2-), resulting in heterolytic products. CH/sub 3/ bound to Mo can dehydrogenate to yield doubly bound CH/sub 2/ but further dehydrogenations are not energetically favorable. These findings indicate it may be possible to incorporate CH/sub 4/ in Fischer-Tropsch catalysis over MoS/sub 2/. A review of theoretical work on structure and electronic factors in heterogeneous catalysis dealing in C=C, C=O, and CH activation by metals and oxides was prepared. The importance of 0/sup -/ to CH/sub 4/ activation is explained.
- Research Organization:
- Case Western Reserve Univ., Cleveland, OH (USA)
- OSTI ID:
- 5633066
- Report Number(s):
- PB-88-142153/XAB
- Country of Publication:
- United States
- Language:
- English
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