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Home _Departments _Chemical Reaction Engineering
Chemical Reaction Engineering
Supported Ionic Liquid Phase (SILP) Catalysis
The ultimate goal in the development of more efficient catalytic materials is to combine the selectivity, specificity and synthetic availability offered by a homogeneous catalyst with the ease of processing and the robustness that can be realized with heterogeneous catalysts. A very promising concept towards this goal of molecular catalysis in heterogeneous systems is the "supported ionic liquid phase (SILP)" catalyst technology. In a SILP catalyst an ionic liquid containing a dissolved transition metal complex is dispersed over the high internal surface of a porous support. Due to the very good wettability of ionic liquids on typical inorganic supports and due to the strong capillary forces, a material results that is macroscopically a dry solid but still contains the dissolved catalyst in its film on support. Due to the extremely low vapor pressure of ionic liquids the SILP materials show excellent stability in continuous gas phase contact (up to 1100 h time-on-stream demonstrated). A schematic representation of a SILP-catalyst is shown in Figure 1.

Figure 1. Schematic representation of supported ionic liquid phase (SILP) materials for catalysis.
By an appropriate choice of the ions (and possible additives) contained in the ionic liquid material, it is possible to transfer specific properties of the fluid to the surface of a solid material by confining the fluid onto the surface. Thus, the SILP concept allows tailor making of solid materials resulting in uniform and well-defined surface topologies with definite properties and a controlled chemical reactivity. The SILP concept thereby constitutes an attractive methodology to circum-vent the lack of uniformity of solids in traditional material science.
The SILP technology provides a great potential to create materials with new surface properties, as the transfer of specific ionic liquid properties to solid surfaces may result in "designer surfaces" having properties which are impossible to realize with present synthetic approaches. Furthermore, the use of established fixed-bed reaction engineering makes these novel materials highly attractive for large scale applications. In catalysis, we have successfully established SILP catalytic materials in hydroformylation, carbonylation and hydrogenation reactions.
At Campus Busan the SILP catalyzed hydroformylation of short chain alkenes (C3 to C5) will be studied. The continuous reactor setup in the CRT labs allows the consecutive reaction cascade of hydroformylation followed by hydrogenation in the presence of an additional nano-SILP catalyst (S1). Newly developed ligands from the University of Eindhoven allow the highly selective formation of branched aldehydes. These intermediates can be converted into optically active alcohols via an enzymatic route (S2). An industrially interesting cascade reaction would be the conversion of pentenes into hexanes according to S3. All reactions will be investigated in a highly sophisticated gas-phase reactor setup consisting of a gradient free Berty type reactor and a combination of two tubular reactors.
In-situ Spectroscopy
The investigation of homogeneous catalysts in molecular solvents as well as in ionic liquids is state of the art. Common techniques are based on NMR, UV-VIS and FT-IR spectroscopy. In most cases the system investigated is either far away from the real conditions (high concentrations in NMR) or lacks the insight into steady state conditions (FT-IR in batch autoclaves). In the Campus Busan research approach a CSTR reactor setup will be combined with an in-situ FT-IR probe based on ATR. Thus, following the catalyst performance over time is possible under steady state conditions and should reduce the amount of time for the determination of kinetic parameters.
A conventional high pressure autoclave is equipped with gas and liquid dosing units (MFC and HPLC), a pressure and volume controller and connected to an online sampling device. In this way, following the reaction both via the active species and the product composition will reveal details about the mechanism.
In-depth Investigations of SILP materials
The newly developed SILP materials show promising results in both catalysis and separation science. The thermal stress during high temperature catalysis or gas purification via temperature swing can lead to small loss of the ionic liquid via gravimetric removal from the support material. Via TG this thermal stability will be studied over extended operation periods.
Furthermore, the film distribution is a crucial aspect for optimized catalyst. Here, a stationary and instationary Wicke-Kallenbach cell will be used to determine the film distribution, pore closures and effective diffusion coefficients.
Research Activities at the Chair of Chemical Reaction Engineering at FAU Erlangen-Nuremberg
Innovative Concepts for highly selective catalyzed reactions and their scale-up
to continous processes.
The common perspective of our research activities at the chair of chemical reaction engineering is the development of new concepts towards highly selective catalytic reactions. This involves development, characterization and investigations of new catalyst systems.
The developed catalyst systems are investigated in industrially relevant reactions that involve complex selectivity problems and have not been successfully solved with existing catalysts. In coexisting projects new concept for the immobilization and regeneration of catalysts, miniaturization and on-line reaction monitoring are methodologically investigated

The fields of research are listed below:
Advanced materials Biomass utilisation
/ valorization
Chemical Vapor
Deposition (CVD)
Heterogeneous catalysis
Homogeneous catalysis Lonic liquids
Immobilization concepts Kinetic modeling
Porous materials Reactor and Miniplant design
Supported lonic Liquid
phase (SLIP)