The transeterification reaction can be catalyzed by both homogeneous and heterogeneous catalysts. Homogeneous catalysts include alkalis and acids. The most commonly used alkali catalysts are NaOH, KOH and the corresponding sodium and potassium alkoxides [14,20,21].
Sulfuric acid, sulfonic acid and hydrochloric acid are usually used as catalysts in the acid-catalyzed reaction.