Modelling of the supported ionic-liquid-Phase (SILP) catalyst system
Zusammenfassung der Projektergebnisse
The project is aimed to improve the modeling of chemical reactions in Supported Ionic Liquid Phase (SILP) catalyst systems by accounting for solubility of substrates in Ionic Liquid (IL). In the first part, the new Thermodynamic Kinetic Model (TKM) for the SILP reaction modeling is introduced. In order to keep consistent thermodynamics, the activity is used for the calculation of the reaction rate instead of commonly used partial pressures or concentrations (black-box modeling, BBM). The activity coefficients are calculated using the Conductor-like Screening Model for Real Solvents (COSMO-RS). Due to the rigorous thermodynamic approach, the modeling quality is improved. The improvement is shown first for a simple test reaction, the hydrogenation of propene. The application of the TKM model results in a better description of the propene hydrogenation kinetics. The activation energy obtained using TKM is higher compared to that from BBM and differ by the value of the evaporation enthalpy of propene so that it is in the range of heterogeneous catalysis reported in literature for analogous reactions. That is due to the fact that by introducing the substrate activity in the reaction rate equation the part of the dissolution process is considered. The partial reaction orders of substrates stay constant for reaction in different ILs. For all ILs studied, the frequency factor is shown to be linearly correlated to the product of “temperature-free” (extrapolated to infinitely large temperature) limiting activity coefficients of substrates powered by the corresponding reaction orders. The partial reaction orders of substrates stay constant for reaction in different ILs. All these could allow for the prediction of the frequency factor for further ILs. The developed model was extended and applied for the hydroformylation of 1-butene to n-pentanal. The extension was aimed at optimizing the substrate-to-product selectivity based on their solubilities. With an extended and improved TKM model, good modeling results are achieved for different ILs. The new TKM is able to accurately describe the temperature dependence of 1-butene conversion for 7 IL’s. Effect of the concentration of 1-butene, CO, and hydrogen on conversion is also modeled very well. With the improved understanding of the SILP catalyst system, a screening function is developed first without accounting for the synthesis gas. Based on consideration of the chemical equilibrium and predicted solubilities of 1-butene and 1-pentanal, the best suited ILs can be identified successfully. On this level of prediction, no kinetic input parameters from the reaction are necessary. For the second screening function, the solubility of the synthesis gas is included. Here, a first experimental measurement for one IL is needed to determine the partial reaction orders. The conversion shows a linear dependence on the second screening function giving potential for predictions. Further, the a-priori prediction of solubility of different solutes in ILs with COSMO-RS is discussed. The activity coefficient at infinite dilution can be predicted with an average accuracy of 0.5 ln-units. The COSMO-RS calculations yield equally good results for different solute classes in ILS with varying cations. A variation of anion may lead to reduced prediction quality depending on its chemical nature. Possible reasons for this finding are missing optimized atomic radii or the specificities of the σ-profiles of some anions. The poor prediction quality for anions such as sulfate and phosphate can be improved by using the scaled isodensity method implemented in Turbomole. In conclusion, the combination of the TKM and COSMO-RS is a powerful toolbox which can be used for the modeling as well as for the predictive optimization of chemical reactions in SILP catalyst systems. By fitting the kinetic parameters of the TKM model to experimental kinetic measurements for one IL, it is possible to predict the reaction rate for different ILs.
Projektbezogene Publikationen (Auswahl)
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Modeling of reactions in immobilized ionic liquids (SILP); Chemie Ingenieur Technik; 80(9), 1262; 2008
Buchele, A., Arlt, W.
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Modeling of the SILP catalysis- Thermodynamic and Kinetic Modeling of the Water Gas Shift Reaction, COIL, Washington, USA, 2011
J. Hartmann, A. Buchele, W. Arlt, S. Werner, P. Wasserscheid
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Thermodynamic and Kinetic Modeling of the Water Gas Shift Reaction using Supported Ionic Liquid Phase Catalyst Systems, AICHE, Minneapolis, USA, 2011
J. Hartmann, A. Buchele, W. Arlt, S. Werner, P. Wasserscheid
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Thermodynamic and Kinetic Modeling of the Water-Gas-Shift Reaction in Supported Ionic Liquids, 8th Congress of Chemical Engineering together with ProcessNet- Annual Meeting, Berlin, Germany, 2011
J. Hartmann, A. Buchele, W. Arlt
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Thermodynamic and Kinetic Modeling of the SILP Reaction for the Hydrogenation of Propene, AICHE, Pittsburgh, USA, 2012
J. Hartmann, A. Buchele, W. Arlt, S. Werner, A. Schönweiz, P. Wasserscheid
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Description of thermodynamic influences on the reaction rate with SILP catalysts, Jahrestreffen Reaktionstechnik, Würzburg, Germany, 2013
J. Hartmann, A. Buchele, W. Arlt
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Modeling of the Supported Ionic Liquid Phase Catalysis; Thesis/Dissertation, Erlangen, 2013
Buchele, A.
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chapter in Fehrmann, R., Riisager, A., Haumann, M.: Supported Ionic Liquids, Elsevier (2014)
Arlt, W., Buchele A.
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Supported Ionic Liquids: Fundamentals and Applications, Chapter 9: A Priori selection of the Type of Ionic Liquid, John Wiley and Sons; 2014
W. Arlt, A. Buchele
