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Biodiesel is an alternative source of renewable energy that can be produced by a transesterification of vegetable oils. Mesoporous molecular sieves, such as SBA-15, due to high surface area and thermal stability are promising precursors for heterogeneous catalysts in the transesterification reaction. In this work, Al-SBA-15 precursor was obtained by direct hydrothermal synthesis, impregnated with different MoO3 contents (5, 10 and 15 wt%) by the pore saturation method, and evaluated as heterogeneous catalyst in the production of biodiesel from a transesterification of soybean oil with methanol. Al-SBA-15 precursor as well as MoO3/Al-SBA-15 catalyst were characterized for its structural characteristic by X-ray diffraction, textural characteristic by N2 adsorption analysis, and thermal stability by thermogravimetric analysis. An experimental planning 22 + 3 CtPt was used to evaluate the influence of MoO3 content and reaction time on biodiesel yield from soybean oil and methanol. The biodiesel content in the final product was obtained by gas chromatography. An average biodiesel yield of 96% was obtained with the catalyst 10%MoO3/Al-SBA-15 under the following reaction conditions: 20:1 methanol/soybean oil molar ratio, and 3 wt% of catalyst loading at 150 °C in 3 h. After five consecutive reaction cycles, the biodiesel yield decreased by about 34%. The density and acidity of the biodiesel produced are within the specified values for commercialization according to international standards.
Graphical abstract
A Jabuticabeira (Myrciaria cauliflora) é uma árvore frutífera nativa brasileira, pertencente à família Myrtaceae, seus frutos possuem grande valor nutricional. As cascas de jabuticaba são uma fonte de antocianinas, os quais são poderosos compostos antioxidantes e apresentam atividade antimicrobiana. Contudo, as cascas de jabuticaba são geralmente descartadas, o que além de gerar resíduos poluentes, promove o desperdício de nutrientes e compostos potencialmente bioativos presentes nessa porção. Assim, com o objetivo de minimizar as alterações e perdas de determinados compostos bioativos, e consequentemente indicar o potencial do aproveitamento do resíduo em escala industrial, o presente trabalho tem com objetivo avaliar a cinética de secagem da casca de jabuticaba e ajustar modelos matemáticos aos dados experimentais. Os frutos foram adquiridos no comércio de Campina Grande/PB, selecionados de acordo com o grau de maturação apropriada para o processamento e ausência de danos físicos (injúrias), lavados e higienizados com solução de hipoclorito de sódio, em seguida foram despolpados manualmente para separação das frações sólidas, polpa, casca e sementes. A secagem foi realizada em uma estufa de circulação de ar forçado, na faixa de temperaturas 45, 50 e 55°C. Os dados experimentais da secagem foram ajustados aos modelos de Page, Midili e Henderson e Pabis. A cinética das cascas de Jabuticaba mostrou que a temperatura influenciou no processo de secagem, e constatou-se que a constante de secagem “k” aumentou com a sua elevação. Ademais, o modelo de Midili apresentou um melhor ajuste comparado aos demais métodos.
MCM-22 is a microporous molecular sieve with a system of sinusoidal three-dimensional channels that do not interconnect themselves, which presents good adsorption capacity and high acidity. Thus, this study aims to evaluate the chemical and structural properties of the catalyst MgO/MCM-22 using wet impregnation method. The synthesis of the zeolite was performed using the static hydrothermal method. Through the XRD patterns, it was possible to observe that the metal incorporation process did not cause structural changes, as well as the analysis showed small peaks related to the magnesium oxide in the structure. The micrographs presented a spherical morphology with depression in the central region. FTIR spectra showed the typical peaks of metal with little differences in the typical peaks of MCM-22.
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