Dismantling and chemical characterization of spent Peltier thermoelectric devices for antimony, bismuth and tellurium recovery

International audienceMajor uses of thermoelectricity concern refrigeration purposes, using Peltier devices, mainlycomposed of antimony, bismuth and tellurium. Antimony was identified as a critical rawmaterial by EU and resources of bismuth and tellurium are not inexhaustible, so it is necessaryto imagine the recycling of thermoelectric devices. That for, a complete characterization isneeded, which is the aim of this work. Peltier devices were manually dismantled in three parts:the thermoelectric legs, the alumina plates on which remain the electrical contacts and thesilicone paste used to connect the plates. The characterization was performed using five Peltierdevices. It includes mass balances of the components, X-ray diffraction analysis of thethermoelectric legs and elemental analysis of each part of the device. It appears that aluminarepresents 45% of a Peltier device in weight. The electrical contacts are mainly composed ofcopper and tin, and the thermoelectric legs of bismuth, tellurium and antimony. Thermoelectriclegs appear to be Se-doped Bi2Te3 and (Bi0,5Sb1,5)Te3 for n type and p type semiconductors,respectively. This work shows that Peltier devices can be considered as a copper ore and thatthermoelectric legs contain high amounts of bismuth, tellurium and antimony compared totheir traditional resources

Psychotria douarrei and Geissois pruinosa, novel resources for the plant-based catalytic chemistry

International audiencePsychotria douarrei and Geissois pruinosa are known as a hypernickelophore plants. The study of their chemical characteristics was revisited to demonstrate a novel potential of this natural resource for Green Chemistry. P. douarrei showed a unique composition, which led to a novel concept of plant-based catalytic chemistry. The supported Biginelli reaction illustrated an interest of this concept for green organic synthesis

Hydrodemetallation and Hydrodesulfurization Spent Catalysts Elemental Analysis: Comparison of Wavelength Dispersive X-ray Fluorescence and Atomic Emission Spectrometries

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A zero-waste process for the management of MSWI fly ashes: production of ordinary Portland cement

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Switchable Alkene Epoxidation/Oxidative Cleavage with H₂O₂/NaHCO₃: Efficient Heterogeneous Catalysis Derived from Biosourced Eco-Mn

A novel Mn-derived catalyst was prepared starting from the biomass of Mn-hyperaccumulating plants growing on metal-rich soils. Recovery of this biomass as value-added “ecocatalyst” provides incentives for the development of phytoextraction programs on soils degraded by mining activities. Characterization of the resulting plant-based catalyst Eco-Mn by inductively coupled plasma mass spectrometry (ICP-MS), X-ray diffraction (XRD), X-ray fluorescence spectrometry (XRF), and X-ray photoelectron spectroscopy (XPS) demonstrated the presence of unusual polymetallic complexes of Mn­(II) in the catalyst, along with Fe­(III). Incorporation of these species into montmorillonite K10 as solid support provided a supported Eco-Mn catalyst, whose properties were investigated for alkene epoxidation with H₂O₂ (30 wt %)/NaHCO₃ (0.2 M) as a green terminal-oxidizing reagent. The supported Eco-Mn catalyst demonstrated a high efficiency for styrene epoxidation, with only 0.31 mol % Mn, a much lower content of Mn than in previously described Mn-derived heterogeneous catalysts. Although Fe was also present in the supported Eco-Mn catalyst, comparison experiments showed that Fe had only a limited role in the catalysis. The water content in the reaction medium had a beneficial effect, increasing the reaction efficiency. The supported Eco-Mn catalyst was recycled four times without any loss of activity. Comparison of its properties to those of heterogeneous catalysts made by incorporation of commercial MnCl₂·4H₂O and FeCl₃·6H₂O highlighted the superior catalytic activity of polymetallic species present in the biosourced catalyst. The substrate scope of the method was extended to various alkenes, including bulky natural products which were epoxidized with high yields (up to 99%), sometimes much higher than those obtained with already described Mn-derived heterogeneous catalysts. Finally, by simple adjustments of reaction conditions, the method allowed controlled access to aldehydes by oxidative cleavage of various styrene-derived substrates (up to 93% yield). The method thus constitutes a valuable alternative not only to classical epoxidation reagents but also to oxidative cleavage of styrene-derived molecules, which usually involves toxic and hazardous reagents

Ecological catalysis and phytoextraction: symbiosis for future

International audienceMetallophyte plants derived from phytoextraction are used as starting materials to prepare novel polymetallic catalysts. Polymetallic catalyst activity is used in many Lewis acid catalyzed reactions according to the polymetallic catalyst preparation. The synergetic catalysis of these systems leads to efficient syntheses of complex biomolecules such as dihydropyrimidinone, 5'-capped DNA and RNA, and glycosyl aminoacid. These new polymetallic catalysts also bring new possibilities in Green Catalysis, that we named "Ecological Catalysis"