Ethene Dimerization and Hydrogenation over a Zeolite-Supported Rh(I)-Carbonyl Complex: Mechanistic Insights from DFT Modeling

Sai V.C. Vummaleti, Alexander Genest, Nishamol Kuriakose, Notker Rösch

Research output: Contribution to journalArticlepeer-review

15 Scopus citations

Abstract

Using DFT calculations within a quantum mechanical/molecular mechanical scheme, we present a model study on a zeolite-supported Rh(I) complex, [Rh(CO)(C2H4)]+, to rationalize the experimentally observed ethene hydrogenation and dimerization. Our computational results show that the coordination of an ethene to the Rh center of a [Rh(CO)(C2H4)]+ complex is thermodynamically favorable over H2 coordination. The diethyl complex [Rh(CO)(C2H5)2]+ resulting from hydrogenation acts as a branching point of two catalytic cycles of ethene conversion, to hydrogenation or dimerization. The Rh-acyl complex [Rh(COCH2CH3)(C2H5)(C2H4)]+ is the in situ-generated active species initiating the dimerization, as it entails a tremendous lowering of the C-C coupling barrier, by more than 100 kJ mol-1. Overall, free energy barriers of ethene hydrogenation (89-92 kJ mol-1) are calculated 4-7 kJ mol-1 lower than the barrier for dimerization, 96 kJ mol-1, in qualitative agreement with the experimentally observed selectivity. Finally, a side reaction of the Rh-acyl complex yields a qualitative explanation of the experimentally observed steady increase in butene selectivity.

Original languageEnglish
Pages (from-to)9836-9846
Number of pages11
JournalACS Catalysis
Volume8
Issue number10
DOIs
StatePublished - 5 Oct 2018

Fingerprint

Dive into the research topics of 'Ethene Dimerization and Hydrogenation over a Zeolite-Supported Rh(I)-Carbonyl Complex: Mechanistic Insights from DFT Modeling'. Together they form a unique fingerprint.

Cite this