Advancement in utilization of nanomaterials as efficient and recyclable solid catalyst for biodiesel synthesis

Energy consumption is increasing day by day, thereby depleting the fossil fuel reserve at an alarming rate. The fossil-based fuels have many adverse effects on the environment and cause global warming due to emission of greenhouse gases. Biodiesel produced via the transesterification process is an alternative, eco-friendly, and renewable fuel. Transesterification is carried out using homogeneous, enzyme, and heterogeneous catalysts. Heterogeneous catalysts can resolve the issues faced by the homogeneous and enzyme catalysts during biodiesel synthesis. At the same time, heterogeneous nanocatalysts have much more potential due to their higher surface area, more selectivity, and stronger catalytic activity. In this review, various nanocatalysts such as metal oxides (CaO, MgO, ZnO, Ti₂O, CuO, and ZrO₂), magnetic nanocatalyst, nano-zeolite catalyst, and nano-hydrotalcite catalysts were studied. In addition, catalyst preparation methods, physical properties of catalyst along with various reaction parameters such as reaction temperature and time, methanol to oil molar ratio (MTOMR), catalyst loading, and biodiesel yield were highlighted and discussed. In short, biodiesel synthesis using nanocatalyst can provide a cheap and clean energy and thus the nanocatalyst can be further developed as a strong candidate for the global energy industry in the future.