About the Acidity-Catalytic Activity Relationship in Ionic Liquids: Application to the Selective Isobutene Dimerization

L. Magna 1, * J. Bildé 1 H. Olivier-Bourbigou 1 T. Robert 2 B. Gilbert 2
* Corresponding author
1 IFPEN - IFP Energies nouvelles
2 Université de Liège
Abstract : The Brønsted acidity level was evaluated for ionic liquids to which a strong acid has been added. As a first approach, the evaluation method was based on the determination of the Hammett acidity functions H0, using UV-Visible spectroscopy. The acidity of protons is mainly determined by their solvation state and consequently, the properties of protons depend on both the nature of the solvent and the nature and concentration of the acid. An apparent acidity scale was defined following this principle. It was found that, for the investigated ionic liquids, the cation does not play a dominant role on the acidity level ([BMIm] ~ [BHIm] ~ [ HNEt3] ), whereas changing the nature of the anion of the ionic liquid may lead to very different acidities ([ SbF6] > [ PF6] > [ BF4] > [ NTf2] > [OTf]). This “acidity scale” was tentatively compared with an “activity scale” obtained for the dimerization of isobutene into isooctenes. The tendencies concerning the cation effect were confirmed ([BMIm] ~ [BuMePyrr] ~ [ HNEt3] ). The anion effect in only partially validated with a different behaviour for NTf2 type ionic liquids ([ NTf2] ~ [ SbF6] > [ PF6] ~ [ BF4] > [OTf]). By an adequate choice of the ionic liquid, selectivity for isobutene dimers can reach 88 wt% (at 70% isobutene conversion) with possible recycling of the catalytic system without loss of activity and selectivity.
Document type :
Journal articles
Complete list of metadatas

Cited literature [55 references]  Display  Hide  Download
https://hal-ifp.archives-ouvertes.fr/hal-02001586
Contributor : Edp Sciences <>
Submitted on : Thursday, January 31, 2019 - 11:37:47 AM
Last modification on : Thursday, February 7, 2019 - 4:29:44 PM
Long-term archiving on : Wednesday, May 1, 2019 - 5:22:59 PM

File

ogst08133.pdf
Publication funded by an institution

Identifiers

Collections

IFP | OGST

Citation

L. Magna, J. Bildé, H. Olivier-Bourbigou, T. Robert, B. Gilbert. About the Acidity-Catalytic Activity Relationship in Ionic Liquids: Application to the Selective Isobutene Dimerization. Oil & Gas Science and Technology - Revue d'IFP Energies nouvelles, Institut Français du Pétrole, 2009, 64 (6), pp.669-679. ⟨10.2516/ogst/2009041⟩. ⟨hal-02001586⟩

Export

BibTeX TEI DC DCterms EndNote

Share

Metrics

Record views

9

Files downloads

11

Contact

support.ccsd.cnrs.fr
hal.support@ccsd.cnrs.fr
Logo CCSD