Biodiesel Production

The majority of biodiesel production employs a transesterification process, producing alkyl or methyl esters using a based catalyzed reaction. This process has proven to be the most economic due to the low temperature and pressure requirements, minimal reaction time, and relatively simple process.

Feedstock: Most any vegetable oil or animal fat can be used to produce biodiesel. Commonly used oil seed crops include soy beans, rapeseed (Canola), and mustard. Waste cooking oil, often called yellow grease, can also be used.

Transesterification: The process begins with the introduction of an alcohol and a catalyst.

• Methanol is typically used as the alcohol.
• The catalyst is either sodium hydroxide (caustic soda) or potassium hydroxide (potash).
• For the processing of waste oils, the reaction requires a two-stage process, using both an acid (sulfuric acid) and a base (sodium/potassium hydroxide).

Separation : The next step is the separation of the glycerine and purification of the methyl esters.

• The glycerine is typically gravity separated. This commodity (92% purity) is sold as crude glycerine without further processing or further refined prior to sale.
• The methyl ester (crude biodiesel) is washed with water to remove any residual catalyst, methanol and glycerine. Methanol is recovered and recycled for future use.

Purification: The methyl ester is then placed in a centrifuge for further purification and to remove the water used in the wash.