Browsing by Author "Blanco, Elodie"

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    Atrazine degradation through a heterogeneous dual-effect process using Fe-TiO2-allophane catalysts under sunlight
    (2024) Castro-Rojas, Jorge; Jofré-Dupre, Pablo; Escalona Burgos, Nestor Guillermo; Blanco, Elodie; Ureta-Zañartu, María Soledad; Mora, Maria Luz; Garrido-Ramírez, Elizabeth
    This study investigated the novel application of Fe-TiO2-allophane catalysts with 6.0% w/w of iron oxide and two TiO2 proportions (10% and 30% w/w) for degrading atrazine (ATZ) using the heterogeneous dual-effect (HDE) process under sunlight. Comparative analyses with Fe-allophane and TiO2-allophane catalysts were conducted in both photocatalysis (PC) and HDE processes. FTIR spectra reveal the unique hydrous feldspathoids structure of allophane, showing evidence of new bond formation between Si-O groups of allophane clays and iron hydroxyl species, as well as Si-O-Ti bonds that intensified with higher TiO2 content. The catalysts exhibited an anatase structure. In Fe-TiO2-allophane catalysts, iron oxide was incorporated through the substitution of Ti4+ by Fe3+ in the anatase crystal lattice and precipitation on the surface of allophane clays, forming small iron oxide particles. Allophane clays reduced the agglomeration and particle size of TiO2, resulting in an enhanced specific surface area and pore volume for all catalysts. Iron oxide incorporation decreased the band gap, broadening the photoresponse to visible light. In the PC process, TiO2-allophane achieves 90% ATZ degradation, attributed to radical species from the UV component of sunlight. In the HDE process, Fe-TiO2-allophane catalysts exhibit synergistic effects, particularly with 30% w/w TiO2, achieving 100% ATZ degradation and 85% COD removal, with shorter reaction time as TiO2 percentage increased. The HDE process was performed under less acidic conditions, achieving complete ATZ degradation after 6 hours without iron leaching. Consequently, Fe-TiO2-allophane catalysts are proposed as a promising alternative for degrading emerging pollutants under environmentally friendly conditions.
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    H2 production through aqueous phase reforming of ethanol over molybdenum carbide catalysts supported on zirconium oxide
    (2024) Pavesi Contreras, Camila Andrea; Blanco, Elodie; Pazo Carballo, César Alexander; Dongil, A.B.; Escalona Burgos, Nestor Guillermo
    Molybdenum carbide catalysts supported on monoclinic and tetragonal zirconium oxide were studied for hydrogen production through aqueous phase reforming of ethanol. Catalysts were characterized by N2 physisorption, XRD, TPR and XPS. Results showed that 10%Mo2C/m-ZrO2 was less carburized and had a lower surface area than 10%Mo2C/t-ZrO2 and 10%MoC/t-ZrO2. Mo oxide was identified on the surface as well as two types of Mo oxycarbide and Mo oxynitride. The α crystalline phase of the carbide was more active than β phase and was ascribed to its higher relative superficial distribution. However, the α phase generated less H2 probably because there was less oxycarbide presence. 10%Mo2C/m-ZrO2 produced significantly more H2 and was stable for five consecutive reactions. This catalyst showed higher carburization degree after the reaction, which greatly enhanced the generation of H2, suggesting that carbides species improved H2 production compared to oxycarbides.
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    H2 production through aqueous phase reforming of ethanol over molybdenum carbide catalysts supported on zirconium oxide
    (Wiley, 2024) Pavesi Contreras, Camila Andrea; Blanco, Elodie; Pazo Carballo, César Alexander; Dongil, A.B.; Escalona Burgos, Nestor Guillermo
    Molybdenum carbide catalysts supported on monoclinic and tetragonal zirconium oxide were studied for hydrogen production through aqueous phase reforming of ethanol. Catalysts were characterized by N2 physisorption, XRD, TPR and XPS. Results showed that 10%Mo2C/m-ZrO2 was less carburized and had a lower surface area than 10%Mo2C/t-ZrO2 and 10%MoC/t-ZrO2. Mo oxide was identified on the surface as well as two types of Mo oxycarbide and Mo oxynitride. The α crystalline phase of the carbide was more active than β phase and was ascribed to its higher relative superficial distribution. However, the α phase generated less H2 probably because there was less oxycarbide presence. 10%Mo2C/m-ZrO2 produced significantly more H2 and was stable for five consecutive reactions. This catalyst showed higher carburization degree after the reaction, which greatly enhanced the generation of H2, suggesting that carbides species improved H2 production compared to oxycarbides.
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    New Pillar-MOF with Nitrogen-Donor Sites for CO2 Adsorption
    (2024) Lancheros Sánchez, Andrés Fernando; Goswami, Subhadip; Zarate, Ximena; Blanco, Elodie; Schott Verdugo, Eduardo Enrique; Hupp, Joseph T.
    A new pillar-MOF [Zn2(L)(DABCO)] was solvo-thermally synthesized by using a new linker (L = 4,4′-(1,4-phenylenebis(3,5-dimethyl-1H-pyrazole-4,1-diyl))dibenzoic acid),Zn(NO3)2·6H2O, and triethylenediamine (DABCO) as pillarlinker. It was characterized using single-crystal X-ray diffraction,powder X-ray diffraction (PXRD), thermogravimetric analysis(TGA), and scanning electron microscopy (SEM) and tested forCO2 adsorption. It exhibits dinuclear paddle−wheel nodes wherethe Zn(II) cations are coordinated by four equatorial L linkersgenerating two-dimensional sheets. DABCO acted as a pillarbinding the sheets to obtain a neutral three-dimensional frameworkthat shows one-dimensional square channels. The new pillar-layered MOF presents micro- and mesopores, and its crystallinity is preserved after activation at 160 °C × 16 h and adsorption ofCO2. Due to the presence of the pyrazole nitrogen atoms in the framework, which have an increased affinity toward CO2, this newmaterial exhibited a reasonable CO2 uptake capacity and a low isosteric enthalpy of adsorption (Hads)