The stoichiometric quantity of methanol is the amount needed to convert triglycerides (fats and oils) into esters (biodiesel) — the “methyl” portion of methyl esters. You also need an excess of methanol to push the conversion process towards completion — without the excess the process runs out (reaches equilibrium) before all the triglycerides are converted to esters, resulting in poor fuel that doesn’t combust well and can be corrosive. The excess methanol acts more like a catalyst: it encourages the process but does not become a part of the final product and can be recovered afterwards.
How Much Methanol Should You Use?
