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Ruiu A, Li WSJ, Senila M, Bouilhac C, Foix D, Bauer-Siebenlist B, Seaudeau-Pirouley K, Jänisch T, Böringer S, Lacroix-Desmazes P. Recovery of Precious Metals: A Promising Process Using Supercritical Carbon Dioxide and CO 2-Soluble Complexing Polymers for Palladium Extraction from Supported Catalysts. Molecules 2023; 28:6342. [PMID: 37687180 PMCID: PMC10488959 DOI: 10.3390/molecules28176342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 08/21/2023] [Accepted: 08/23/2023] [Indexed: 09/10/2023] Open
Abstract
Precious metals such as palladium (Pd) have many applications, ranging from automotive catalysts to fine chemistry. Platinum group metals are, thus, in massive demand for industrial applications, even though they are relatively rare and belong to the list of critical materials for many countries. The result is an explosion of their price. The recovery of Pd from spent catalysts and, more generally, the development of a circular economy process around Pd, becomes essential for both economic and environmental reasons. To this aim, we propose a sustainable process based on the use of supercritical CO2 (i.e., a green solvent) operated in mild conditions of pressure and temperature (p = 25 MPa, T = 313 K). Note that the range of CO2 pressures commonly used for extraction is going from 15 to 100 MPa, while temperatures typically vary from 308 to 423 K. A pressure of 25 MPa and a temperature of 313 K can, therefore, be viewed as mild conditions. CO2-soluble copolymers bearing complexing groups, such as pyridine, triphenylphosphine, or acetylacetate, were added to the supercritical fluid to extract the Pd from the catalyst. Two supported catalysts were tested: a pristine aluminosilicate-supported catalyst (Cat D) and a spent alumina supported-catalyst (Cat A). An extraction conversion of up to more than 70% was achieved in the presence of the pyridine-containing copolymer. The recovery of the Pd from the polymer was possible after extraction, and the technological and economical assessment of the process was considered.
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Affiliation(s)
- Andrea Ruiu
- ICGM, University Montpellier, CNRS, ENSCM, 34293 Montpellier, France; (A.R.); (W.S.J.L.)
| | - W. S. Jennifer Li
- ICGM, University Montpellier, CNRS, ENSCM, 34293 Montpellier, France; (A.R.); (W.S.J.L.)
| | - Marin Senila
- INCDO-INOE 2000, Research Institute for Analytical Instrumentation, ICIA, 400293 Cluj-Napoca, Romania;
| | - Cécile Bouilhac
- ICGM, University Montpellier, CNRS, ENSCM, 34293 Montpellier, France; (A.R.); (W.S.J.L.)
| | - Dominique Foix
- IPREM, Université de Pau et des Pays de l’Adour, E2S-UPPA, CNRS, 64053 Pau, France;
| | | | | | - Thorsten Jänisch
- Fraunhofer Institute for Chemical Technology, 76327 Pfinztal, Germany; (T.J.); (S.B.)
| | - Sarah Böringer
- Fraunhofer Institute for Chemical Technology, 76327 Pfinztal, Germany; (T.J.); (S.B.)
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Ruiu A, Bouilhac C, Gimello O, Seaudeau-Pirouley K, Senila M, Jänisch T, Lacroix-Desmazes P. Synthesis and Phase Behavior of a Platform of CO2-Soluble Functional Gradient Copolymers Bearing Metal-Complexing Units. Polymers (Basel) 2022; 14:polym14132698. [PMID: 35808744 PMCID: PMC9269141 DOI: 10.3390/polym14132698] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Revised: 06/24/2022] [Accepted: 06/26/2022] [Indexed: 12/10/2022] Open
Abstract
The synthesis and characterization of a platform of novel functional fluorinated gradient copolymers soluble in liquid and supercritical CO2 is reported. These functional copolymers are bearing different types of complexing units (pyridine, triphenylphosphine, acetylacetate, thioacetate, and thiol) which are well-known ligands for various metals. They have been prepared by reversible addition–fragmentation chain-transfer (RAFT) polymerization in order to obtain well-defined gradient copolymers. The copolymers have been characterized by proton nuclear magnetic resonance (1H-NMR) spectroscopy, matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry, thermal gravimetric analysis (TGA), dynamical scanning calorimetry (DSC) and cloud point measurements in dense CO2. All the investigated metal-complexing copolymers are soluble in dense CO2 under mild conditions (pressure lower than 30 MPa up to 65 °C), confirming their potential applications in processes such as metal-catalyzed reactions in dense CO2, metal impregnation, (e.g., preparation of supported catalysts) or metal extraction from various substrates (solid or liquid effluents). Particularly, it opens the door to greener and less energy-demanding processes for the recovery of metals from spent catalysts compared to more conventional pyro- and hydro-metallurgical methods.
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Affiliation(s)
- Andrea Ruiu
- ICGM, Univ. Montpellier, CNRS, ENSCM, 34293 Montpellier, France; (A.R.); (O.G.)
| | - Cécile Bouilhac
- ICGM, Univ. Montpellier, CNRS, ENSCM, 34293 Montpellier, France; (A.R.); (O.G.)
- Correspondence: (C.B.); (P.L.-D.)
| | - Olinda Gimello
- ICGM, Univ. Montpellier, CNRS, ENSCM, 34293 Montpellier, France; (A.R.); (O.G.)
| | | | - Marin Senila
- INCDO INOE 2000, Research Institute for Analytical Instrumentation, ICIA, 400293 Cluj-Napoca, Romania;
| | - Thorsten Jänisch
- Fraunhofer Institute for Chemical Technology, 76327 Pfinztal, Germany;
| | - Patrick Lacroix-Desmazes
- ICGM, Univ. Montpellier, CNRS, ENSCM, 34293 Montpellier, France; (A.R.); (O.G.)
- Correspondence: (C.B.); (P.L.-D.)
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