OBTAINING DIFFERENT TYPES OF NIIBUM STRUCTURES BY THE TEMPLATES-FREE HYDROTHERMIC METHOD AND ITS APPLICATION IN OBTAINING BIODIESEL FROM SUNFLOWER OIL
Hydrothermal method. Nb sources. Nb structures. Biodiesel
Environmental problems are often caused by human actions. The use of fossil fuels, in addition to being a non-renewable energy, generates toxic gases when burned that end up polluting the air. In view of this, the use of biodiesel, which is a renewable energy, emerges as an alternative, coming from a green process, since with the use of raw material of oleaginous origin, it allows them to be captured by the plants, reducing the emission of carbon dioxide. With regard to the development of heterogeneous catalysts, this method allows for easy recovery after the reaction process. Obtaining different types of catalysts can be acquired by modifying the synthesis sources, allowing the formation of different types of structures. These materials can possess novel physical and chemical properties, high surface-to-volume ratios, as well as surface properties at such a scale. With regard to the advantages of using niobium-based materials, it is important to emphasize that this metal is abundant in Brazil, in addition to having a wide range of applications, such as in electrochemistry and catalysis . Thus, the objective of this work is to obtain niobium structures, with different types of synthesis precursors through alkaline hydrothermal synthesis, free of templates impregnated with nickel oxide for application in biodiesel. These materials were characterized in order to determine and compare their structural properties such as XRD, SEM, TG/DTG and FTIR. The SEM results showed that it was possible to obtain different types of Nb morphologies by changing the sources of synthesis by the method used, providing the formation of the morphology of tubular structures and cubes. XRD analysis indicated that the structures obtained are composed of sodium niobates. The insertion of nickel metal in the best condition of tubular morphology catalyst was efficient according to the physicochemical analyses. Thermogravimetric analyzes show that the tubular structures presented a good catalytic activity with conversion of 90% of fatty acids into methyl esters. In view of this, the application of these tubular catalysts in a transesterification reaction are promising materials since they present a high conversion in the formation of biodiesel.