JCJC SIMI 7 - JCJC - SIMI 7 - Chimie moléculaire, organique, de coordination, catalyse et chimie biologique

Multi-component Assembled Architectures incorporating CO2 for Selective Capture of Rare Earth – MA2RCO2SCARE

Promoting CO2 for the selective separation of precious metals included in waste material of high technology devices

Rare Earth metals, key ingredients of high technology devices are threatened by a shortage in their supply. This project proposes to develop disruptive technologies involving low-energy costs to capture and recycle those elements from complex mixtures obtained from waste material

Selective separation of rare earth metals through self-assembling into solid metal organic frameworks : from proof of concept to industrial process

Multicomponent Dynamic Combinatorial Chemistry is an innovative strategy that we currently develop. It can easily deliver adaptative systems displaying high degrees of selectivity in terms of molecular recognition. In that perspective, we have recently designed CO2-induced self-assembling systems, which reversibly incorporate the greenhouse gas into their molecular structure. The objective of this project consists in extending this concept to the capture of strategic metals such as rare earth into reversible solid structures. The long term goal is to design a molecular toolbox allowing to selectively capture and release each metal of the whole series from mixtures through a, paving the way toward a cost-reduced hence economically attractive recycling process, while promoting carbon dioxide as a auxiliary of capture and purification.

The methodology we have adopted originates from conventional combinatorial chemistry. It consists in a screening of the molecular ingredients leading to the formation of a self-assembled solid phase exclusively in the presence of one of the metals from the series. The key parameter is the formation of a solid phase produced by the spontaneous molecular self-organization process. In a second step, the screening can be conducted on a mixture of two or more metals. The subsequent task then consist in the analysis of the molecular composition of the material in particular the relative metal yields of capture. This step is critical to the selection of the hits and the validation of the process. A subsequent step consist in determining the physical and chemical conditions that may lead to the dissociation of the solid material and the concomitant release of the captured metal as a pure species. Eventually, new analytical tools are developed to explore the complex structure of the multi-component supramolecular materials obtained. They should allow to elucidate the origin of the selectivity observed as well as the factors influencing the reversibility of the system. Such information should be crucial to efficiently design new generations of molecular systems for metal capture.

In the presence of trivial commercial building blocks such as carbon dioxide, mixtures containing metals from technological waste spontaneously trigger the self-assembling of a organometallic supramolecular solid.

During this step, the metals themselves such as rare earth metals act as templates inducing the formation of their own matrix of selective encapsulation, whereas transition metals which may be present remain in solution (on mixtures of metals composing last generation magnets, selectivity factors up to 200 can be reach in one step). The metal hence plays an active role as it directs the synthesis and assembling of its own ligands resulting from the coupling between carbon dioxide and amines.

As a result, CO2 can be promoted as a molecular switch allowing the selective capture and release, ie the straightforward purification of strategic metals. Between its extraction from exhaust fumes and its utilization to produce valuable material, it can be used in such a cycle to generate some wealth through urban mining. This transient use of CO2 re-boost recycling and transformation program by coupling its market to strategic metal markets.

Several patents were and are being filled (chemical system, process). This project supported by the ANR has allowed to further obtain two additional maturation grants for continuous transfer and development toward the industrial world. This research axis is also supported by the iMuST Labex (Excellence fellowship to the main investigator) and the pole de compétitivité Axelera.

In full agreement with the working plan submitted to the ANR, the future prospects of the project will both concern fundamental and applied aspects. While the proof of concept has been validated and patented, time has come to explore the structure of the molecular architectures obtained in order to determine the physical interactions and effects underpinning their unprecedented selectivity. Such analyses will allow to provide enough data and knowledge on the identified hits for their publication. On the technological field, the screening process will be applied to metal mixtures corresponding to current industrial challenges, in order to identify selective hits that could lead to potential green processes and licensing agreements. Expansion of the molecular toolbox (in terms of building blocks) may also be envisaged from the lessons learned from the structural analyses.
Very recently the last generation of molecular system was successfully implemented into a pilot at the laboratory scale (partnership with the Laboratory of Chemical Engineering and Processes, member of the iMuSt LABEX). A new patent is currently being filled under the supervision of the Société d’Accélération de Transfert de Technologie Pulsalys. This actor has also recently announced its wish to support a technological development project devoted to designing a future process and build a pre-industrial demonstrator.

PCT Int. Appl. (2014), WO 2014188115 A1 201411272.
Fr. Demande (2014), FR 3005741 A1 20141121
Chem. Sci. 2016 under revision
Eur. Patent. 2016 pending (march)
Acc. Chem. Res. oct 2016 invited paper

The MA2RCO2SCARE project aims at obtaining highly selective receptors for rare earth metals through the use of multicomponent dynamic combinatorial chemistry, in a perspective of separation and extraction from complex post-consumer mixtures. The targeted system combines two organic covalent reversible linkages that have proved to be excellent ligands for rare earth. These linkages have also been successfully combined in libraries yielding selective and reversible systems of CO2 capture in our group. In the present project, the screening will be conducted using synthetically trivial building blocks and the hits identified from their ability to form organized nanoscopic structures with the metal. This selection process should macroscopically translate into a phase separation from the starting library. A particular attention will be devoted to the thermodynamic control of the process, allowing to subsequently dissociate the architecture formed upon physical or chemical stimulation, in order to recycle each chemical component including the metal. Beyond the proof of principle, the long term objective consists in applying this molecular toolbox to the separation of valuable metals through urban mining.

Project coordination

Julien LECLAIRE (Université)

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.

Partner

ISM2 - UMR CNRS 7313 Institut des Sciences Moleculaires de Marseille - equipe Chirosciences - groupe catalyse et biochiralité

Help of the ANR 158,999 euros
Beginning and duration of the scientific project: October 2012 - 36 Months

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