Browsing by Author "Silva Barbieri, Daniela Carolina"

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    Corrosion Analysis of a High Entropy Alloy for Ammonia Production
    (2024) Sancy Velásquez, Mamie Odette; Silva Barbieri, Daniela Carolina; Walczak, Magdalena Marta
    Global energy demand has increased significantly due to world population growth and the industrialization of developing economies. Energy production has been based mainly on fossil-fuel energy, which has increased global warming due to the rise of greenhouse gases in the atmosphere, such as carbon dioxide. According to the Energy Institute, renewable power generation through wind, solar, and other renewable sources, represent only 40,86% of energy sources in 2022 [1]. An alternative energy source for fossil fuels is hydrogen, which can be produced through renewable resources that increase energy efficiency. However, the storage and transportation of hydrogen present a series of technical challenges, resulting in high costs and motivating the development of intermediate technologies. Recently, ammonia generated by renewable energy sources has gained significant attention as an energy carrier, a medium to store and transport chemical energy, and directly as fuel [2]. Ammonia is also a primary raw material for making inorganic fertilizers, pharmaceuticals, synthetic fibers, resins, and other applications, benefiting nearly half the world's population. Ammonia can be transported more efficiently and safely than hydrogen in tanker vessels or pipelines due to its relative ease of being liquefied at room temperature and moderate pressure, increasing energy density. Currently, ammonia is produced mainly from hydrogen and nitrogen by the Haber-Bosch process, which utilizes fossil fuel, thus resulting in carbon dioxide emissions. Ammonia production can also involve the non-spontaneous nitrogen reduction reaction by electrochemical techniques, which uses hydrogen that can be provided from the water, reducing energy consumption and carbon dioxide emissions. However, the non-spontaneous nitrogen reduction reaction has low activity, and its voltage is close to that of the hydrogen evolution reaction. Plasma and electrothermal chemical cycle methods have been explored to improve the selectivity of non-spontaneous nitrogen reduction reactions. Several studies have proposed new catalysts to increase the active sites, modify the size and morphology of particles, and introduce defects, such as transition metal-based catalysts, carbon-based catalysts, phosphorus-based catalysts, etc. Nevertheless, traditional catalysts frequently degrade rapidly due to the harsh chemical environment and the inherent corrosiveness of the reactions involved. A highly active catalyst that degrades quickly due to corrosion offers limited practical value. Researchers are exploring novel materials like high-entropy alloys (HEAs) to address this challenge, which also have high corrosion resistance [3]. This study focuses on the potential of a HEA, FeCrMnNiCo, as a catalyst for the electrochemical conversion of nitrogen to ammonia via the electrochemical method, evaluating the influence of the microstructure on its mechanical properties, catalytic activity, and corrosion resistance. A ball burnishing deformation was applied to the HEA at different conditions. The X-ray diffraction revealed that the FeCrMnNiCo alloy presented a face-centered cubic crystalline structure, and scanning electron microscopy analysis showed that the alloying elements were segregated in the deformed samples. The mechanical deformation determined both catalytic activity and corrosion resistance of the HEA.
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    Estabilización proteica de vinos blancos mediante adsorción con óxido de circonio soportado en alúmina porosa
    (2025) Silva Barbieri, Daniela Carolina; Pérez Correa, José Ricardo; Escalona Burgos, Néstor; Pontificia Universidad Católica de Chile. Escuela de Ingeniería
    La presencia de turbidez en las botellas de vino blanco es un defecto relevante para los consumidores, aun cuando no afecta su calidad. La turbidez en vinos es causada principalmente por proteínas inestables relacionadas con la patogénesis de la uva, que permanecen estables durante el proceso de vinificación, pero que pueden precipitar debido a cambios bruscos de temperatura después del embotellado. Existen métodos para reducir las proteínas en el vino, pero se sigue investigando la manera más adecuada de eliminarlas selectivamente. Tradicionalmente, se utiliza bentonita, pero este proceso es lento, genera pérdidas de vino y residuos perjudiciales para el medio ambiente. Además, es intensivo en mano de obra, difícil de automatizar, costoso y afecta negativamente el color y aroma del vino, ya que no es específico para las proteínas inestables. Por ello, se necesitan procedimientos alternativos que mejoren el proceso convencional en varios aspectos. El óxido de circonio (ZrO2) elimina eficazmente las proteínas sin afectar las características del vino. Sin embargo, la producción de materiales de ZrO2 rentables con capacidades eficientes de eliminación de proteínas representa un desafío significativo. Este proyecto investiga una manera más económica y eficaz de aprovechar el potencial del óxido de circonio mediante su impregnación en alúmina de bajo costo y gran superficie activa. El adsorbente óptimo logró una notable reducción en la turbidez, disminuyendo el ΔNTU de 42 a 18, junto con una significativa reducción del 44 % en el contenido total de proteínas, y una reducción de proteínas en el rango de peso molecular de 10 a 70 kDa. Este resultado se atribuye a la modificación de las propiedades texturales de ZrO2/Al2O3, caracterizadas por la reducción de sitios ácidos, el aumento de los diámetros de poro de 4,81 a 7,74 nm y la aparición de cúmulos de circonia en la superficie del soporte poroso.