Browsing by Author "Pazo Carballo, César Alexander"

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    Cobalt-based core@shell catalysts for guaiacol hydro conversion: use of salicylic acid as a sacrificial modulator of the interaction between the metal phase and the silica support
    (2024) Aguirre Abarca, Diego Alejandro; Pazo Carballo, César Alexander; Laurenti, Dorothee; Karelovic, Alejandro; Dongil, Ana B.; Escalona Burgos, Néstor Guillermo
    In this work, four cobalt-based catalysts were obtained using two routes of preparation which differed in the expected degree of interaction with the silica matrix, using salicylic acid as a sacrificial modifier during the synthesis to modulate the interaction between the cobalt phase and the silica support due to its complexing properties. The catalysts were tested for the hydroconversion of guaiacol at 300 degrees C and 5 MPa of H2, with clear differences between each procedure. It is found that the synthesis route has a deep impact on the catalytic activity, with the catalysts prepared using a one-pot route being less active and having an increased selectivity to cyclohexane. In contrast, the ones prepared using a two-step process have increased yield towards phenol and cyclohexanol under the conditions used herein. Salicylic acid increases the catalytic activity in comparison to the untreated material for both families of materials, without changing the observed selectivity between samples with the same preparation., Salicylic acid as a cobalt-based catalyst modifier enhances the activity with increased selectivity towards cyclohexanol. This is linked to changes induced by the modifier over the cobalt surface, allowing for tuning of the catalytic activity.
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    Conversion of succinic acid over Ni and Co catalysts
    (2021) Rojas Guerrero, Mabel Natalia; Zarate, X.; Canales Muñoz, Roberto; Dongil, A. B.; Pazo Carballo, César Alexander; Saavedra Torres, M.; Escalona, Néstor
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    Separation of furfuryl alcohol from water using hydrophobic deep eutectic solvents
    (2023) Cea Klapp, Esteban; Arroyo Avirama, Andrés Felipe; Ormazábal Latorre, Sebastián Alejandro; Gajardo Parra, Nicolás F.; Pazo Carballo, César Alexander; Quinteros Lama, Héctor; Marzialetti, Teresita; Held, Christoph; Canales Muñoz, Roberto; Garrido, José Matías
    Furfuryl alcohol (FA) is an important organic chemical feedstock that must be separated from water to upgrade it into high-value-added products. Since FA forms an azeotrope with water, liquid-liquid extraction is a suitable option for separating both compounds. This work evaluates the separation of FA from water using hydrophobic deep eutectic solvents (DES). Three DES were prepared using menthol, thymol, and octanoic acid by combining them in molar ratio as follows: thymol + octanoic acid (1:2), menthol + octanoic acid (1:2), and thymol + menthol (1:1). Experimental liquid-liquid equilibria (LLE) of ternary systems water + FA + DES measured at 313.15 K and 101.13 kPa were used to determine the distribution coefficient and selectivity values for FA when using each DES. The experimental results were compared with molecular dynamics (MD) using Martini 3 force field and modeled using Perturbed-Chain Statistical Associating Fluid Theory (PC-SAFT) without any adjustable binary parameters. According to the results, selectivities and distribution coefficients using hydrophobic DES have comparable values to traditional volatile organic compounds (VOCs) used to separate FA from water. In general, DES shows better distribution coefficients compared with typical organic solvents. According to the results, a good alternative would be menthol + octanoic acid (1:2) or thymol + menthol (1:1) to replace typical VOCs. MD and PC-SAFT provide accurate estimations for ternary LLE in the range of examined thermodynamic conditions, which confirms the predictive consistency of both approaches. Microscopic properties computed with MD simulations evidence a surface activity or absolute adsorption of FA in the interfacial region, which is correlated with favorable distribution coefficients and selectivities.