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Supported ruthenium catalysed selective hydrogenation of citral in presence of [NTf2]- based ionic liquids

Arras, Jürgen and Ruppert, Dominik and Claus, Peter (2009):
Supported ruthenium catalysed selective hydrogenation of citral in presence of [NTf2]- based ionic liquids.
In: Applied Catalysis A: General, pp. 73-77, 371, (1-2), [Online-Edition: http://dx.doi.org/10.1016/j.apcata.2009.09.034],
[Article]

Abstract

The influence of ionic liquids (ILs) based on the bis(trifluoromethanesulfonyl)amide anion ([BMIM][NTf₂] and [HMIM][NTf₂]) on the alumina supported ruthenium catalysed liquid-phase hydrogenation of citral was investigated applying these ILs as additive. For characterisation ICP-OES, hydrogen pulse chemisorption and nitrogen physisorption were applied, the latter was used after reaction to identify the presence of an ionic liquid layer on the catalyst. The catalytic results show that under the chosen reaction conditions (373 K, 7 MPa H₂, 0.3 mol L⁻¹ citral), additives like [NTf₂]− based ionic liquids change the intramolecular selectivity (C=O vs. C=C hydrogenation) in a way that the desired unsaturated alcohols geraniol and nerol are the main products (Smax = 46% at X = 50% compared to only 25% for neat Ru/Al₂O₃). Concerning the catalyst activity a decrease of the initial turnover frequency (0.048 s⁻¹) in comparison to the IL-free catalyst (0.140 s⁻¹) was observed. The results indicate that in presence of [BMIM][NTf₂] and [HMIM][NTf₂] the site-time yields towards citronellal were more decreased than for geraniol and nerol enhancing the selectivity of the latter ones.

Item Type: Article
Erschienen: 2009
Creators: Arras, Jürgen and Ruppert, Dominik and Claus, Peter
Title: Supported ruthenium catalysed selective hydrogenation of citral in presence of [NTf2]- based ionic liquids
Language: English
Abstract:

The influence of ionic liquids (ILs) based on the bis(trifluoromethanesulfonyl)amide anion ([BMIM][NTf₂] and [HMIM][NTf₂]) on the alumina supported ruthenium catalysed liquid-phase hydrogenation of citral was investigated applying these ILs as additive. For characterisation ICP-OES, hydrogen pulse chemisorption and nitrogen physisorption were applied, the latter was used after reaction to identify the presence of an ionic liquid layer on the catalyst. The catalytic results show that under the chosen reaction conditions (373 K, 7 MPa H₂, 0.3 mol L⁻¹ citral), additives like [NTf₂]− based ionic liquids change the intramolecular selectivity (C=O vs. C=C hydrogenation) in a way that the desired unsaturated alcohols geraniol and nerol are the main products (Smax = 46% at X = 50% compared to only 25% for neat Ru/Al₂O₃). Concerning the catalyst activity a decrease of the initial turnover frequency (0.048 s⁻¹) in comparison to the IL-free catalyst (0.140 s⁻¹) was observed. The results indicate that in presence of [BMIM][NTf₂] and [HMIM][NTf₂] the site-time yields towards citronellal were more decreased than for geraniol and nerol enhancing the selectivity of the latter ones.

Journal or Publication Title: Applied Catalysis A: General
Volume: 371
Number: 1-2
Uncontrolled Keywords: Ionic liquid; Additive; Modifiers; Liquid-phase hydrogenation; Citral; ?,?-Unsaturated aldehydes; Intramolecular selectivity
Divisions: 07 Department of Chemistry
07 Department of Chemistry > Fachgebiet Technische Chemie > Technische Chemie II
07 Department of Chemistry > Fachgebiet Technische Chemie
Date Deposited: 21 Sep 2009 07:43
Official URL: http://dx.doi.org/10.1016/j.apcata.2009.09.034
Additional Information:

Available online 8. Oktober 2009

Identification Number: doi:10.1016/j.apcata.2009.09.034
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