Widely Used Catalysts in Biodiesel Production: A Review

Abstract

<p>An ever-increasing energy demand and environmental problems associated with exhaustible fossil fuels have led to the search for an alternative renewable source of energy. In this context, biodiesel has attracted attention worldwide as an alternative to fossil fuel for being renewable, non-toxic, biodegradable, carbon-neutral; hence eco-friendly. Despite homogeneous catalyst has its own merits, currently, much attention has been paid to chemically synthesize heterogeneous catalysts for biodiesel production as it can be tuned as per specific requirement, easily recovered, thus enhance reusability. Recently, biomass-derived heterogeneous catalysts have risen to the forefront of biodiesel productions because of their sustainable, economical and eco-friendly nature. Further, nano and bifunctional catalysts have emerged as a powerful catalyst largely due to their high surface area and potential to convert free fatty acids and triglycerides to biodiesel, respectively. This review highlighted the latest synthesis routes of various types of catalysts including acidic, basic, bifunctional and nanocatalysts derived from different chemicals as well as biomass. In addition, the impacts of different methods of preparation of catalysts on the yield of biodiesel are also discussed in details.</p>

Biomass‐based heterogeneous catalysts for biodiesel production: A comprehensive review

“…Among the most widely used heterogeneous base catalysts (MgO, CaO, SrO, mixtures of oxides), calcium oxide (CaO) stands out for its high catalytic activity 14,39 . It is obtained by heat treatment at a high temperature (generally higher than 600°C) from calcium carbonate (CaCO 3 ).…”

“…Homogeneous catalysts have a variety of applications in biodiesel industry due to their high catalytic activity and availability. Homogeneous base catalysts have been extensively investigated 14 and implemented in industry, but they are strongly affected by the presence of free fatty acids (FFA), which hampers the transesterification reaction due to the formation of surfactant molecules that favor the appearance of stable emulsions in the purification stage. The previous acid esterification of oil is an alternative route to reduce the FFA content.…”

“…However, the use of heterogeneous catalysts brings some limitations. These include weak catalytic activity, catalytic site leaching, 18,19 and microporosity 9,14 . Studies 20‐23 reveal that enzyme‐based catalysts have several advantages over other catalysts, they achieve adequate yields, the biodiesel obtained is of higher quality, and it is an environmentally friendly process.…”

Optimization of the enzymatic butanolysis of jatropha oil for biodiesel production using Eversa

“…Different catalysts have been evaluated for this reaction, including basic, acid, and enzymatic. Supercritical process have also been considered 5–9 . For biodiesel to be competitive against fossil fuel, cheaper raw materials need to be used so that the processing cost can be reduced from 70–80% of the overall biodiesel productions cost 10,11 .…”

“…Supercritical process have also been considered. [5][6][7][8][9] For biodiesel to be competitive against fossil fuel, cheaper raw materials need to be used so that the processing cost can be reduced from 70-80% of the overall biodiesel productions cost. 10,11 To achieve this goal, the reactants are have more impurities.…”