Browsing by Author "Araya-Lopez, Claudio"

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    Aqueous Phase Hydrogenation of 4-(2-Furyl)-3-buten-2-one over Different Re Phases
    (2024) Diaz, Claudio Ignacio C.; Araya-Lopez, Claudio; Dongil, A. B.; Escalona, Nestor
    4-(2-furyl)-3-buten-2-one (FAc) is obtained by aldol condensation of furfural and acetone and has been used in hydrodeoxygenation reactions to obtain fuel products using noble metal catalysts. The hydrogenation of FAc in the aqueous phase using metallic- and Re oxide-supported catalysts on graphite was studied, within a temperature range of 200-240 degrees C, in a batch reactor over a 6 h reaction period. The catalysts were characterized using N2 adsorption-desorption, TPR-H2, TPD-NH3, XRD, and XPS analyses. Catalytic reactions revealed that metallic rhenium and rhenium oxide-supported catalysts are active for the hydrogenation and Piancatelli rearrangement of FAc. Notably, metallic rhenium exhibited a fourfold higher initial rate than rhenium oxide, which was attributed to the higher dispersion of Re in the Re/G catalyst over graphite. Re/G and ReOx/G catalysts tended to rearrange and hydrogenate FAc to 2-(2-oxopropyl)cyclopenta-1-one in water.
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    Rhenium(VII) extraction from sulfuric aqueous solutions using ionic liquids as diluent and extractant: insights on the extraction stoichiometry and process parameters
    (2022) Quijada-Maldonado, Esteban; Roman, Rodrigo; Merlet, Gaston; Perez, Barbara; Cabezas, Rene; Tapia, Ricardo; Olea, Felipe; Villarroel, Eduardo; Araya-Lopez, Claudio; Romero, Julio
    BACKGROUND Rhenium(Re) is a highly valuable metal recovered from molybdenite leach liquors by solvent extraction (SX) using toxic organic solvents. This work proposes an extracting phase free of volatile organics composed by the ionic liquid (IL) trioctylmethylammonium benzoate [TOMA][BA] as the extractant, due to its ability to extract Re(VII), and the IL 1-octyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [omim][Tf2N] as the diluent, due to its high hydrophobicity where the extraction stoichiometry and process parameters such as the initial pH, the extractant concentration in the diluent and stripping using ammonium hydroxide (NH4OH) and sodium hydroxide (NaOH) were assessed. RESULTS This extracting phase yielded high extraction percentages: 95% with only 3% (v/v) of [TOMA][BA] in [omim][Tf2N]. A detailed study of the SX stoichiometry was carried out through slope analysis, showing that the SX occurs in two steps: first, the extraction of acid; then, the extraction of the metal ion via anion exchange with the transfer of IL-diluent anion to the aqueous phase. Additionally, the extracting phase was tested in a synthetic molybdenite leached pregnant leach solution, showing selectivity towards Re(VII) over Cu(II) and Fe(III) at very low extractant concentration. The stripping of Re(VII) from the loaded phase was also studied achieving 60% stripping in only one equilibrium step when using NH4OH. CONCLUSION This novel extracting phase, free of volatile organic, shows promising Re(VII) extraction for future industrial applications. (c) 2021 Society of Chemical Industry (SCI).