Hydrogenation in Monolith Reactor: a new technology for safe, sustainable and selective units. – HYDROMORE

Through the Hydromore project, the original idea of an intensified heat exchange reactor is proposed for future industrial hydrogenation units. It consists in a monolith-type reactor offering parallel channels of mm scale, dedicated alternatively to the reaction and to the circulation of a cooling fluid. Ideally the monolith structure is made of a highly heat-conducting material (metal, silicon carbide).
This new kind of multiphase monolith-type reactor will offer many advantages: good ability to reduce heat and mass transfer resistance, especially in the so-called Taylor flow (bubbles - slugs), which is crucial for fast exothermic reactions; convenience to high pressure and temperature; weak axial dispersion in the liquid phase, leading to better chemical conversion and to less wastes; laminar flow, allowing identification of data and test of catalysts; low pressure drop; safety for reactor operation (as the reactants cut-off leads to rapid reactor draining and stops the reaction).
Important gains are then expected, thanks to the better control of mass transfer steps, heat removal, and temperature level.

This new reactor will be applied to the hydrogenation of a bio-sourced olefin, alpha-pinene, and of an edible oil, sunflower oil (rich in linolenic and linoleic fatty acids, molecules to be hydrogenated for food conservation purpose).
For the complete hydrogenation of the terpene, the reaction yield should be improved, inducing cost and energy savings for the further step of product separation.
For the treatment of the edible oil, the selectivity of the reaction towards monoene and with respect to isomerisation reactions should be increased, so that the amount of unhealthy saturated trans fats in the hydrogenated products could be minimized.

Some data and knowledge related to this project can be found in literature, upon which the project will lean: studies dedicated to monolith reactors and to catalyst optimization for hydrogenation reactions, models for gas-liquid mass transfer in Taylor flow. Some rare studies have tackled the question of heat evacuation in monoliths. The major barrier to the achievement of the project consists however in the coupling of phenomena that occur simultaneously inside the reactor (momentum, mass and heat transfers, diffusion, reaction); this coupling makes the control, modelling and design of the reactor complex. Another question that arises is the technical feasibility to coat with a catalytic layer the materials considered in this project for monolith walls (SiC…).
To face these difficulties six partners will collaborate, with complementary competence fields:
- the group Total-Fluides has developed a strong expertise in catalytic hydrogenation of fossil fluids through its four hydrotreating units of Oudalle (France), and is keen on industrializing a novel cutting edge process.
- Deposition of washcoats of metal catalysts has been studied and applied to metal-made monoliths at the Centre Interuniversitaire de Recherche et d’Ingénierie des Matériaux (Toulouse).
- Investigation and modelling of selective hydrogenation kinetics have been performed at the Laboratoire de Génie Chimique (Toulouse), as well as operation and dynamic modelling of fixed bed reactors.
- A specific analytical technique for on-line and in situ measurements of vegetable oils composition has been developed at the Laboratoire de Chimie Agro-Industrielle (Toulouse).
- Experimental measurement of local mass transfer fluxes near bubble caps and films in a tube has been successfully tested at LGC by means of a laser technique.
- The numerical analysis of Taylor bubble flows in pipes and capillaries has been performed at the Laboratoire d’Ingénierie des Systèmes Biologiques et des Procédés (Toulouse).
- The modelling of gas-solid exothermal reactions within monolith-type reactors has been achieved at Laval University (Canada).
- Eco-design of products and processes has been performed at LCA.