PETR 110 |
| Acid base catalyzed alkane activation in zeolites is a key reaction to utilize light alkanes. Activation is preceded by the polarization of the C-H bond by bridging hydroxy groups or Lewis acid sites. Unique to the zeolites the alkanes can interact with well defined three dimensional sites consisting of more than one site simultaneously. Such interactions can lead to very effective activations even at low temperatures. The polarization by large multivalent Lewis acid sites (such as La3+) is by far stronger than by bridging hydroxy groups leading to cleavage of hydrogen from alkanes already at mild reaction temperatures. Carbenium ions are the main reacting species at these mild conditions and chain reactions involving hydride transfer dominate after the initiation. The difference to the high temperature route of dehydrogenation via protolytic alkane activation is related to the different polarizations in the adsorbed state. The potential to use these routes in alkane conversion routes will be discussed. |
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Zeolite Catalysis for Green Chemistry in Synthesis of Chemicals and Fuels
1:20 PM-5:30 PM, Tuesday, April 8, 2008 Morial Convention Center -- Rm. 208, Oral
Division of Petroleum Chemistry |