Catalytic mechanism of the dehydrogenation of ethylbenzene over Fe–Co/Mg(Al)O derived from hydrotalcites
Type
ArticleAuthors
Tope, Balkrishna B.Balasamy, Rabindran J.
Khurshid, Alam
Atanda, Luqman A.
Yahiro, Hidenori
Shishido, Tetsuya
Takehira, Katsuomi
Al-Khattaf, Sulaiman S.
KAUST Grant Number
K-C1-019-12Date
2011-11Permanent link to this record
http://hdl.handle.net/10754/600098
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Show full item recordAbstract
Catalytic mechanism of ethylbenzene dehydrogenation over Fe-Co/Mg(Al)O derived from hydrotalcites has been studied based on the XAFS and XPS catalyst characterization and the FTIR measurements of adsorbed species. Fe-Co/Mg(Al)O showed synergy, whereas Fe-Ni/Mg(Al)O showed no synergy, in the dehydrogenation of ethylbenzene. Ni species were stably incorporated as Ni2+ in the regular sites in periclase and spinel structure in the Fe-Ni/Mg(Al)O. Contrarily, Co species exists as a mixture of Co3+/Co2+ in the Fe-Co/Mg(Al)O and was partially isolated from the regular sites in the structures with increasing the Co content. Co addition enhanced Lewis acidity of Fe3+ active sites by forming Fe3+-O-Co 3+/2+(1/1) bond, resulting in an increase in the activity. FTIR of ethylbenzene adsorbed on the Fe-Co/Mg(Al)O clearly showed formations of C-O bond and π-adsorbed aromatic ring. This suggests that ethylbenzene was strongly adsorbed on the Fe3+ acid sites via π-bonding and the dehydrogenation was initiated by α-H+ abstraction from ethyl group on Mg2+-O2- basic sites, followed by C-O-Mg bond formation. The α-H+ abstraction by O2-(-Mg 2+) was likely followed by β-H abstraction, leading to the formations of styrene and H2. Such catalytic mechanism by the Fe 3+ acid-O2-(-Mg2+) base couple and the Fe 3+/Fe2+ reduction-oxidation cycle was further assisted by Co3+/Co2+, leading to a good catalytic activity for the dehydrogenation of ethylbenzene. © 2011 Elsevier B.V. All rights reserved.Citation
Tope BB, Balasamy RJ, Khurshid A, Atanda LA, Yahiro H, et al. (2011) Catalytic mechanism of the dehydrogenation of ethylbenzene over Fe–Co/Mg(Al)O derived from hydrotalcites. Applied Catalysis A: General 407: 118–126. Available: http://dx.doi.org/10.1016/j.apcata.2011.08.032.Sponsors
This publication was based on work supported by Award No. K-C1-019-12 made by King Abdullah University of Science and Technology (KAUST). The support of King Fahd University of Petroleum and Minerals (KFUPM) is also highly appreciated. The XAFS measurements at the SPring-8 were carried out by the approval (proposal No. 2010B1184) of Japan Synchrotron Radiation Research Institute (JASRI). The authors also acknowledge Japan Cooperation Center, Petroleum (JCCP) for giving the opportunity of this collaborative research.Publisher
Elsevier BVJournal
Applied Catalysis A: Generalae974a485f413a2113503eed53cd6c53
10.1016/j.apcata.2011.08.032