Biodiesel is a renewable source of energy from vegetable oil.

Biofuels play a dual role in the transport industry. Currently, they are the only direct substitutes for fossil fuels used in transportation that are widely available and can be used today in normal vehicle engines (unmodified for low-content mixes or slightly modified to accept high-content mixes). It should also be reminded that diesel is the main fuel used in Europe. Another important advantage of using biofuels is the impact they have on reducing greenhouse gas emissions.

Moreover, the biodiesel obtained from rapeseed helps the European Union to increase its production of grits to feed animals, while reducing the volume of imports of soybean grits. Each litre of biodiesel produced from rapeseed means about 1.5 kg feed for cows, pigs or chickens, which are then used as feed for humans.

Plants
EXPUR has built a new plant with a capacity of 100,000 tonnes to produce biodiesel which is supplied with oil produced within the factory and whose production is mainly marketed on the local market.

Processing
The factory is designed to produce methyl esters from a mixture of vegetable oils, as a raw material, through a reaction between triglycerides and methanol, in the presence of an alkaline catalyst. Glycerine is obtained as a by-product, which is separated from the product.

The methanol that did not participate in the reaction is eliminated between the methyl ester and glycerine production phases. Since both side reactions occur under humid conditions, guaranteeing a reaction system that is as dry as possible is essential. For this purpose, the oil jet is subjected to quick drying before it is pumped into the transesterification unit and the excess methanol is subjected to rectification before being recycled for transesterification.

The methyl ester jet resulting from the transesterification unit is then subjected to a purification process in order to remove excess methanol, moisture and impurities. The separate glycerine jet from the transesterification unit is also subjected to a purification process, in order to remove dissolved methanol and impurities incorporated during the transesterification reaction.

In order to maximize the total yield of methyl ester, the fatty acids resulting from the glycerine purification step are subjected to an esterification reaction with acid catalyst, which allows their conversion to methyl ester by direct esterification with methanol; high-acidity frying oil can also be mixed with fatty acids and introduced into the esterification unit.