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Mass transfer assessment and kinetic investigation of biphasic catalytic systems

Julcour-Lebigue, Carine and Blanco, Jean-François and Barthe, Laurie and Delmas, Henri and Poli, Rinaldo and Manoury, Eric and Gayet, Florence and D'Agosto, Franck and Lansalot, Muriel and Deshpande, Raj M. and Kelkar, Ashutosh A. Mass transfer assessment and kinetic investigation of biphasic catalytic systems. (2018) In: Congrès national de la Société Chimique de France, 2 July 2018 - 4 July 2018 (Montpellier, France).

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Efficient catalyst recovery and recycling is still a major challenge for the development of homogeneous catalysis. In the 80’s, the concept of biphasic catalysis, in which the catalyst is confined into a solvent immiscible with the products, has opened new perspectives for transition metal complex driven homogeneous catalysis, after the industrial success of the Ruhrchemie/Rhone-Poulenc process operating the rhodium-catalyzed hydroformylation of propene in water. However, the low solubility of long-chain a-olefins has limited the scope of hydrosoluble catalysts for this reaction. To overcome this problem, various strategies have been developed since then, which consist in replacing water by a more suitable solvent or using additives/ligands able to increase the substrate solubility or create a favorable microenvironment in the aqueous phase. Apart from the screening/tailoring of solvent and ligand, the determination of an adequate kinetic model and the assessment of the mass transfer role is of great importance for the design and optimization of the multiphase reaction system. This presentation gives an account of collaborative works between chemical engineering and chemistry teams to address these issues for two different biphasic catalysis approaches: catalyst immobilization in ionic liquids and use of amphiphilic polymer ligands. The hydroformylation of oct-1-ene by rhodium complexes was selected as model reaction for the developed methodology. This includes the thermodynamic study of the complex reaction medium (gas-liquid and liquid-liquid equilibria), the thorough investigation of the effect of process parameters to evaluate the location of the catalytic act and the interfacial mass transfer resistance, the discrimination and identification of intrinsic kinetic models (derived from elementary reaction steps) and their coupling with (gas-liquid) mass transfer under low stirring conditions. In the first example, the role of the ionic liquids as solvents for biphasic catalysis was specified, by characterizing the solubility of both gaseous and organic substrates, and a detailed kinetic model was able to accurately describe the time-concentration profiles of reactants and products (1-octene,internal octenes, n-nonanal and branched aldehydes) measured in the organic phase. TOF values could be further improved (up to 560 h-1) by supporting the ionic liquid phase onto a silica gel support. In the second example, the proof of concept of cross-linked micelles as efficient supports for aqueous phase catalysis was established, demonstrating that the reaction occurs within the nano-objects with fast exchange with the organic phase. The study also provided clues for their optimization: a low functionalization degree and a nanogel structure embedding the phosphine moieties were proved to improve the catalytic activity and reduce the metal leaching, respectively. These innovative ligands yielded TOF in the range of 350 to 650 h-1 and linear/branched aldehyde ratios between 3 and 6. The Rh loss could be reduced to 0.1 ppm with adequate pH and temperature conditions.

Item Type:Invited Conference
Audience (conference):National conference proceedings
Uncontrolled Keywords:
Institution:French research institutions > Centre National de la Recherche Scientifique - CNRS (FRANCE)
Other partners > Ecole Supérieure de Chimie Physique et Electronique de Lyon (FRANCE)
Université de Toulouse > Institut National Polytechnique de Toulouse - Toulouse INP (FRANCE)
Other partners > Institut universitaire de France - IUF (FRANCE)
Other partners > National Chemical Laboratory - NCL (INDIA)
Université de Toulouse > Université Toulouse III - Paul Sabatier - UT3 (FRANCE)
Other partners > Université Claude Bernard-Lyon I - UCBL (FRANCE)
Laboratory name:
Centre franco-indien pour la Promotion de la Recherche avancée ; Agence Nationale de la Recherche
Deposited On:20 Nov 2018 14:51

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