Abstract
The traditional method of biodiesel synthesis is costly on industrial scale. Hence, heterogeneous catalysis is crucial in minimizing end-product costs thanks to high durability, efficiency, and substantial reusability. A significant criterion for impacting the biological production and survival of the farm is the renewable benefit of biodiesel feedstock and catalyst. The state-of-the-art biodiesel processing technologies for easy and low-cost production processes paid great attention to heterogeneous catalysts. The unique feature of the heterogeneous catalyst is its acid-based, surface, and pore tuning characteristics, which significantly enhance its flexible process feedstock. This review deals with the generations of biofuels, an overview of biodiesel synthesis and production processes, biodiesel production steps, raw materials for biodiesel production, heterogeneous catalysis, advantages of solid acid catalysis, the chemistry of heterogeneous acid catalysis, mechanism of heterogeneous acid catalysis, factors influencing the transesterification reaction, physico-chemical properties, purification of crude biodiesel, physico-chemical characterization of biodiesel, problems associated with the currently employed catalysts for biodiesel production, disadvantages and potential remedies with strong acid catalysts. Because of advanced technologies, there are several benefits to using heterogenous catalysts, such as simple, safe, cost-effective, and efficient biodiesel manufacturing. This review suggests that the utilization of heterogenous catalysts as solid catalysts in biodiesel synthesis looks promising.
•Generations of biofuels, synthesis, raw materials and heterogeneous catalysis were discussed.•Chemistry and mechanism of heterogeneous acid catalysis reported.•Physico-chemical properties and characterization and purification of crude biodiesel reported.•Problems associated with the currently employed catalysts for biodiesel production were investigated.