Ethene hydrogenation vs. dimerization over a faujasite-supported [Rh(C2H4)2] complex. A computational study of mechanism12. Issue 1 (28th November 2016)

• Record Type: Journal Article
• Authors: Govindasamy, Agalya; Markova, Velina K.; Genest, Alexander; Rösch, Notker
• Is Part Of: Catalysis science & technology. Volume 7:Issue 1(2017)
• Page Start: 102
• Page End: 113
• Publication Date: 2016-11-28
• Subjects: Catalysis -- Periodicals; 541.395
• DOI: 10.1039/c6cy02147f
• Languages: English
• ISSNs: 2044-4753

Abstract

Abstract : A DFT study allows one to understand the selectivity for ethene hydrogenation over dimerization by the well-characterized faujasite-supported [Rh(C2 H4 )2 ] + complex. Abstract : Single-site catalysts offer great chances for unraveling the mechanism and the selectivity of catalytic mechanism, in particular when the system is experimentally well characterized. A particular interesting system of this type is the hydrogenation and the dimerization of ethene by the faujasite-supported complex [Rh(C2 H4 )2 ] + . We have examined this system computationally, treating periodic models with a density functional method. The complex [Rh(C2 H4 )2 ] + binds in a bidentate fashion, as previously suggested, inside the faujasite supercage at the oxygen atoms of a 12-member ring. The calculations on this model complex showed ethene hydrogenation to be preferred over dimerization. The highest free energy barrier for forming a C–H bond was calculated at 33 kJ mol −1 at room temperature. This value is significantly lower than the lowest activation free energy, 97 kJ mol −1, calculated for C–C bond formation. The results of this mechanistic study allow one to rationalize the experimental observation that the faujasite-supported [Rh(C2 H4 )2 ] + complex in the presence of H2 is active for hydrogenation, producing ethane as the main product.