IMMOBILIZATION OF REUSABLE OLEFIN METATHESIS CATALYSTS : APPLICATIONS IN BATCH & CONTINUOUS FLOW – CFLOW-OM

Chemical industry must perform a deep mutation in order to create innovative, more environmentally friendly technologies. In this context, olefin metathesis appears as an organometallic reaction having a tremendous potential, and is increasingly used in industrial processes because it shortens production pathways to complex molecules and consequently reduces both production costs and the environmental impact.
The aim of this research project is to develop an economically profitable process for the transformation of vegetable oils in valuable chemicals using olefin metathesis and a novel library of tunable Ru-based supported catalysts. The self-metathesis of methyl oleate will be the targeted reaction. In order to lower metal leaching, a major drawback in olefins metathesis, two routes will be explored, depending on the interactions between the ruthenium and the support: 1) use of traditional fixed bed reactors with innovative immobilized catalysts or 2) use of catalysts designed for reversible interactions with solid supports in an innovative reverse flow process.
The first route implies drastic efforts to improve catalysts life-time and recycling. Three strategies will be considered for the immobilization: 1) Ionic interactions between an ionic liquid and ionic-tagged catalysts, and impregnation on very promising bio-supports obtained from chitosan or alginates; 2) Reversible interactions between the catalyst and either an amorphous or a mesopored functionalized silica, thanks to Charge Transfer Complexes (CTC) Tags or carbon nanotubes, via p-p interactions. 3) Covalent immobilization of the Ru-complex on a mesostructured functionalized silica leading to isolated and permanently supported Ru-active single sites on silica. These materials must exhibit an optimal compromise between catalytic activity and stability of the metallic species. A key point will be the catalyst robustness, which will ensure no degradation with long-term production time in continuous flow applications and no leaching, thus no toxic metallic residues release in the product. The catalytic material must be obtained both in large quantities and costless for industrial applications.
The second route concerns the use of those catalysts that are prone to metal leaching because of weak interactions with the support thus not eligible for the first route. For such cases, the use of a reverse-flow adsorption reactor (RFAR) is proposed. RFAR displays adsorption/desorption sections surrounding a reaction section. The supported catalysts will be used as active species reservoirs, liberating the unsaturated Ru-complex upon olefins feeding. The reactor section will be strictly homogeneous, since the functionalized support by labile ligands will remain in the adsorption section, ready to readsorb the catalyst. The design and use of such dynamic reactors imply researches on adsorption/desorption equilibria, kinetics and reactor simulation and modelling.
The final objective is the set up of two industrial processes for the transformation of vegetable oils in valuable chemicals. These processes must be cost effective while being environmentally friendly.
The partnership of the project involves five complementary academic teams (ENSCR, Université de Paris Sud (UPS-XI), ENSICAEN, CPE-LCOMS and CPE-LGPC at Lyon), one end-user industrial chemical company (NOVANCE-OLEON), French Institute specialists in oils, fats and derivative products (ITERG) and a start-up (OMEGA CAT SYSTEM) whose business activity is focused on the promotion of technologies associated with olefin metathesis. Being successful, the project will deliver both breakthrough technologies and fundamental knowledge in the fields of olefin metathesis, catalyst-support interactions and reactor design for homogeneously catalysed reactions.