Lithium ions incorporation in MgO for oxidative dehydrogenation/cracking of propane: Active site characterization and mechanism of regeneration
✍ Scribed by C. Trionfetti; S. Crapanzano; I.V. Babich; K. Seshan; L. Lefferts
- Book ID
- 104010146
- Publisher
- Elsevier Science
- Year
- 2009
- Tongue
- English
- Weight
- 491 KB
- Volume
- 145
- Category
- Article
- ISSN
- 0920-5861
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✦ Synopsis
In the case of Li-promoted MgO two different mechanisms for regeneration of the active site are found when varying the temperature between 550 and 700 8C. Propane titration showed that the active site is deactivated through formation of hydroxyl groups that are stable at 550 8C and below in absence of oxygen. On the contrary at 700 8C, propane pulses resulted in hydrocarbon activation, accompanied by evolution of water molecules. In addition, simultaneous evolution of hydrogen molecules pulsing propane indicate that ODH of propane follows a mixed heterogeneous-homogeneous radical chemistry. No CO x was observed while pulsing propane at both temperatures. Moreover CO x molecules were not detected even during catalyst regeneration by pulsing oxygen showing that Li/MgO materials are not affected by coke formation. Formation of CO x molecules seems to be feasible exclusively by co-feeding propane and oxygen.