Continuous selective hydrogenation of citral in a trickle-bed reactor using ionic liquid modified catalysts

Wörz, Nicolai; Arras, Jürgen; Claus, Peter

doi:10.1016/j.apcata.2010.06.025

Cited by 33 publications

(20 citation statements)

References 22 publications

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“…5. Selective citral hydrogenation with Pd-based SCILL catalysts using the IL [C 4 C 1 Im][N(CN) 2 ] was also applied continuously in a trickle-bed reactor [97].…”

Section: Solid Catalyst With Ionic Liquid Layer (Scill)mentioning

confidence: 99%

Ionic Liquids in Catalysis

2014

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Ionic liquids (ILs), salts with melting points below 100°C, represent a fascinating class of liquid materials typically characterized by an extremely low vapor pressure. Besides their application as new solvents or as electrolytes for electrochemical purposes, there are two important concepts of using ILs in catalysis: Liquid-liquid biphasic catalysis and IL thin film catalysis. Liquid-liquid biphasic catalysis enables either a very efficient manner to apply catalytic ILs, e.g. in Friedel-Crafts reactions, or to apply ionic transition metal catalyst solutions. In both cases, phase separation after reaction allows an easy separation of reaction products and catalyst re-use. One problem of liquidliquid biphasic catalysis is mass transfer limitation. If the chemical reaction is much faster than the liquid-liquid mass transfer the latter limits the overall reaction rate. This problem is overcome in IL thin film catalysis where diffusion pathways and thus the characteristic time of diffusion are short. Here, Supported Ionic Liquid Phase (SILP) and Solid Catalyst with Ionic Liquid Layer (SCILL) are the two most important concepts. In both, a high surface area solid substrate is covered with a thin IL film, which contains either a homogeneously dissolved transition metal complex for SILP, or which modifies catalytically active surface sites at the support for SCILL. In each concept, interface phenomena play a very important role: These may concern the interface of an IL phase with an organic phase in the case of liquidliquid biphasic catalysis. For IL thin film catalysis, the interfaces of the IL with the gas phase and with catalytic nanoparticles and/or support materials are of critical importance. It has recently been demonstrated that these interfaces and also the bulk of ILs can be investigated in great detail using surface science studies, which greatly contributed to the fundamental understanding of the catalytic properties of ILs and supported IL materials. Exemplary results concerning the IL/vacuum or IL/gas interface, the solubility and surface enrichment of dissolved metal complexes, the IL/support interface and the in situ monitoring of chemical reactions in ILs are presented.

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“…5. Selective citral hydrogenation with Pd-based SCILL catalysts using the IL [C 4 C 1 Im][N(CN) 2 ] was also applied continuously in a trickle-bed reactor [97].…”

Section: Solid Catalyst With Ionic Liquid Layer (Scill)mentioning

confidence: 99%

Ionic Liquids in Catalysis

2014

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“…Furthermore, Pd and Pt supported on SiO 2 and Al 2 O 3 catalysts coated with [BMIM][N(CN) 2 ] have been the subject of several investigations related to H 2 adsorption and interaction of IL with the metals [22][23][24][25]. In a recent study, SiO 2 and Al 2 O 3 supported Pd catalysts coated with [BMIM][N(CN) 2 ] have also been investigated for the hydrogenation of citral resulting in increased selectivity for citronelal [26]. SCILL concept has been also successfully tested in the consecutive hydrogenation of butadiene to butene and butane, in a gas phase reaction, it was observed that the IL strongly favors formation of butane over a Pd-catalyst [27,28].…”

Section: Introductionmentioning

confidence: 97%

Ionic liquid layer on Pd/C catalyst: Membrane-like effect on the selectivity for multistep hydrogenation reactions

Nassor

Tristão

Santos

et al. 2012

Journal of Molecular Catalysis A: Chemical

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“…For monofunctional catalysts, the SCILL concept has been already successfully demonstrated in a number of studies, mostly for hydrogenation reactions [18][19][20][21][22][23][24]. In SCILL catalysis, a traditional heterogeneous catalyst is coated with a thin film of ionic liquid to modify the catalyst's activity and/or selectivity.…”

Section: Introductionmentioning

confidence: 99%