CE07 - Chimie moléculaire et procédés associés pour une chimie durable

Catalysis in water by super hydrophobe hollow shells as solid micelles – CATCALL

CATalysis in water by development of super hydrophobe CApsules as soLid miceLles

CATCALL focuses on the discovery of selective and stable catalysts in the presence of water or in an aqueous medium that does not use noble metals. This breakthrough innovation would allow a major advance in the context of the sustainable development of chemistry.<br />CATCALL aims to design and understand the operation of supported super-hydrophobic SOLID catalysts<br />in solid-liquid-gas and solid-liquid-liquid multiphase heterogeneous processes

CATCALL focuses on the discovery of selective and stable catalysts in the presence of water or in an aqueous medium that do not use noble metals.

• Se placer dans des conditions thermodynamiques favorables. La compréhension de la thermodynamique aux interfaces des différents constituants du système (solvant, réactifs, produits incluant les produits intermédiaires) est un problème complexe. En effet, ce type de problématique soulève de nombreuses questions quant aux effets de co-adsorption/compétition, de solubilité locale, etc. En particulier, il sera nécessaire dans ce projet de quantifier l'impact du caractère superhydrophobe sur les concentrations des réactifs mais aussi la concentration des produits. Il est notamment nécessaire de garder à l'esprit que les réactifs et les produits finaux et/ou intermédiaires peuvent jouer le rôle de « cheval de Troie » qui facilitait la diffusion de l'eau au sein de la porosité. CATCALL devra déterminer le niveau d'hydrophobie optimal et les applications catalytiques favorables (réactifs, produits). Notamment, il sera considéré des conditions d'hydroformylation en excès de H2 permettant une hydrogénation sélective en alcool correspondant, produit très soluble, favorisant sa désorption.<br /><br />• Se placer dans le régime cinétique/catalytique et procédé favorable. Au-delà des aspects statiques, la détermination des constantes de temps est un autre enjeu majeur de notre projet. De nombreuses étapes de diffusion/transport peuvent limiter l'activité catalytique des catalyseurs – les principaux risques étant : (1) la vitesse de dissolution des gaz, (2) la diffusion des réactifs/produits dans le support microporeux et (3) la vitesse de désorption du (des) produit(s) dans la phase aqueuse. La détermination des constantes de temps dans ces milieux complexes car hétérogènes et multi-échelles est un défi à la fois technique et scientifique. CATCALL devra déterminer les conditions catalytiques favorables en termes de réacteurs et de conditions opératoires. Notamment, la mise en œuvre des catalyseurs dans un panier statique avec un réacteur de type CSTR à mode continu sera étudiée.

To achieve these ambitious objectives, three scientific locks will be leveraged:

• Synthesis, material chemistry. The synthesis of ship-in-a-bottle type catalysts is a major challenge. The microporous walls of the supports - of the zeolitic or MOF type - could allow the diffusion of the reagents/products but also be superhydrophobic to prevent the diffusion of water. In addition, the catalysts must have a size greater than the diameter of the micropores in order to ensure their permanent retention at the heart of the particles. These two points are in themselves a real challenge, but the skills developed in recent years in our consortium have already made it possible to synthesize this type of system.

First main results on the design of super hydrophobe capsule have been published!

The design of efficient separation and catalytic processes in nanoporous adsorbents requires to finely tune gas adsorption in their porosity. Here, using a large set of Si-rich zeolites (Silicalite-1, Beta, Chabazite, ITQ-13), we report on an experimental study of vapor adsorption in zeolites showing the pivotal role of the hydroxyl concentration. By studying the adsorption of water and methanol in zeolites assisted with in situ IR and 29 Si NMR measurements, we find that adsorption switches from non-wetting to wetting as the hydroxyl surface density reaches the same critical value ~2.5 OH/nm2. While this hydroxyl concentration-induced crossover is well-known for water, we extend here the concept of a critical concentration by showing that a consistent picture arises when different polar substrates are considered. In particular, by establishing a generic behavior between the two protic substrates (H2O, MeOH), we pave the way for the rational design of hydrophobic adsorbents

Dimerization and oligomerization of light olefins is an important route to produce linear and branched higher olefins. Molecular complexes based on transition metals (Zn, Cr, Ni, Ti, etc.) are effective catalysts for producing linear alpha olefins (C4, C8 and C10) which are the main products of interest. However, in industrial processes, the catalyst is lost in the products and therefore cannot be reused or recycled. In some cases, the presence of a cocatalyst (often an alkyl aluminum salt) is necessary to initiate the catalytic cycle. Nevertheless, the stability of the cocatalyst in the presence of water is an obstacle to its use in a non-anhydrous or aqueous medium because they hydrolyse easily and lose their activity. In this context, we wish to design hydrophobic porous support materials protecting the molecular catalyst and its cocatalyst.

1/ The Pivotal Role of Critical Hydroxyl Concentration in Si-Rich Zeolites for Switching Vapor Adsorption
HAL Id : hal-03420234, version 1
DOI : 10.1021/acs.jpcc.1c07124

CATCALL deals with the discovery of selective and stable catalysts in water media without the use of noble metals.
The objecives are to design and to understand the mechanisms of SOLID superhydrophobe catalysts in multiphasic processes.

The role of the superhydrophobic catalyst support is to 1) prevent water to access to catalytic sites and 2) enable an overconcentration of substrates on catalytic sites in a kind of 'Liquid with Permanent Porosity"

Project coordination


The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.


LIPHY Laboratoire Interdisciplinaire de Physique

Help of the ANR 359,369 euros
Beginning and duration of the scientific project: December 2019 - 48 Months

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