Removal of Thiophenic Sulfurs Using an Extractive Oxidative Desulfurization Process with Three New Phosphotungstate Catalysts

Three Keggin-type phosphotungstates, i.e. [C5H5NH]3PW12O40, [C4H6N2H]3PW12O40·3C4H6N2 and [(C4H9)4N]3PW12O40, were synthesized and characterized by elemental analysis, X-ray diffraction, and infrared spectra, meanwhile their catalysis in an extractive catalytic oxidative desulfurization process was studied with ionic liquid (IL) as extractant and H2O2 as oxidant. The main factors affecting the desulfurization process were investigated, including temperature, hydrophobicity of IL, and variety of S-compounds, as well as the amount of catalyst, IL, and H2O2. Under the optimal conditions, the S-content of DBT oil can be decreased from 1000 to 2 ppm. A new interpretation is proposed for the current process, in which IL is assumed as a reaction phase, and the amount of the extracted S-compound and the peroxidized catalyst wherein greatly affect the desulfurization rate. Besides, the IL with the dissolved catalyst can be reused many times and regenerated easily

Simultaneous Extraction of Both Basic and Non-basic N‑Compounds from Oil <i>via</i> Triethylene Glycol–Metal Complex Solvent: Performance and Behavior

Simultaneous extraction of basic and non-basic N-compounds from oil is still a big challenge. Triethylene glycol (TEG) encounters very weak Brønsted acidity. Its N-distribution coefficient [DN, (mmol·gEx–1)/(mmol·gOil–1)] for the basic was below 7.0. In this work, metals dissolved in TEG can improve the Lewis acidity of the extractant and bring about the simultaneous removal. For example, DN of TEG–Ag­(I) can increase to 40.5 for quinoline and 57.9 for pyridine, respectively. For the non-basic, it still remained higher than 70.0. The promoted performance was ascribed to the improvement of extractive behavior of the basic. From TEG to TEG–Ag­(I), first, the distribution of equilibrium N-concentrations between two phases was significantly changed from the straight line to the non-linear curve with the plateau. Second, the interaction type inside the system was optimized. The Ag­(I)-based complexation coupled with the TEG-based H-bonding was identified. Third, the interaction intensity was increased as well. Ag­(I) contributed much to reduction of Gibbs free energy change for the basic. Therefore, enhancing Lewis acidity of the extractant was a feasible way for the extraction of the N-compounds

A Green and Efficient Solvent for Simultaneously Leaching Co and Li from Spent Li-Ion Batteries: Dicarboxylated Polyethylene Glycol

Recovery of high-valued metals such as Li and Co from spent Li-ion batteries is quite important for sustainability reasons. The novelty of this work was based on the view of molecular design, proposing a strategy that inserts another group between two −COOH groups on an organic acid to activate them. On this basis, a novel solvent dicarboxylated polyethylene glycol (dcPEG), i.e., HOOC–CH2(CH2CH2O)nCH2–COOH, was chosen to leach Li and Co from LiCoO2. Expectedly, HOOC–CH2(CH2CH2O)nCH2–COOH (n = 250), which was denoted as dcPEG250, showed appealing leaching performance without the help of H2O2 and quaternary ammonium salt. It can simultaneously extract Co and Li, and the leaching efficiency reached as high as almost 100% under the proper conditions. The excellent performance was ascribed to structural feature of dcPEG. The presence of main chain (CH2CH2O)n extended the distance between two −COOH groups at the ends, limited their intramolecular interaction, and activated the −COOH groups. Accordingly, the active H atom on the −COOH group can react with LiCoO2, and the active O atoms on ether (C–O–C) and carbonyl (CO) groups can coordinate with metals. In a word, this work could not only provide a promising solvent but also inspire researchers to engineer more novel solvents from the view of molecular design