Sustainable inorganic nanocatalysts in biodiesel production - A review on recent developments

About 88% of the fuels used for energy generation are generated from oil. The use of fossil fuels (FFs) has been declining recently due to oil supplies depletion and associated issues like global warming and environmental degradation brought on by the emissions of gases like CO₂ and SO_x. Researchers have therefore been looking for energy sources other than FFs. One of the alternatives that has been frequently observed during the past ten years is biodiesel. Biodiesel is a blend of fatty acid methyl esters (FAME) made from sustainable resources including animal and vegetable fats, making it an ecologically unharmful and biodegradable fuel. This sustainable energy source has received significant attention lately because of the depletion of FFs, rising greenhouse gas emissions, and environmental pollution. Diesel engines can use biodiesel without any modifications. The concentration of contaminants such as hydrocarbon compounds, CO and particulate matter is reduced when biodiesel is added to diesel and used in diesel engines. However, inefficiencies in industrial processes are the root cause of the high cost of producing biodiesel. There are numerous methods for creating biodiesel, such as microemulsion, transesterification, esterification (EST) and pyrolysis reactions. Transesterification is one of the methods that has the most promise for increased output. This article critically analyses recent advances in advanced biodiesel synthesis methodologies via sustainable nanocatalysts (NC) like metal oxides, magnetic nanoparticles etc., and discusses operating variables that affect biodiesel yields.