Population growth and the development of cities requires large energy needs, however, it comes from fossil fuels such as oil, however, its use has unfavorable consequences to society related to its polluting effect. One way to slow down such damages is to use less polluting fuels, such as biofuels. Biodiesel is used as a suitable substitute for conventional diesel, since it is a renewable fuel obtained through the process of transesterification from raw materials such as vegetable oils, animal fats, used cooking oils, and also because Brazil presents only suitable for cultivating oilseed varieties. In order for biodiesel production to occur efficiently, the transesterification and esterification reactions require the presence of a catalyst. Basic homogeneous catalysis is the most used form of biodiesel production, but requires refined and water-free raw material. In addition, the commonly used catalysts (NaOH, KOH, etc.) are environmentally aggressive and require a neutralization step. Heterogeneous catalysts have been shown to be efficient in transesterification reactions, as they are reusable and do not require a neutralization step after the reaction. With this purpose, the objective of this work was to study the application of heterogeneous catalysts obtained from natural sources (dolomite, crab shell, eggshell and fish scales). They have some advantages such as abundance, low cost, porous structure and non-toxic. The heterogeneous catalysts studied are promising and viable in the transesterification reaction for biodiesel production.
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