Continuous method for the heterogenically catalyzed esterification of fatty acids

Continuous process for esterifying free fatty acids present in starting materials, comprising the steps of:

• 1) removing the free fatty acids from the remaining starting material by distillation or rectification,
• 2) reacting the deacidified starting material remaining after step 1) in a transesterification to obtain fatty acid alkyl esters,
• 3) reacting the free fatty acids with alcohols using at least one acidic catalyst in a fixed bed, in an esterification reaction,
• 4) removing the water formed as a by-product in step 3), optionally together with at least a portion of the alcohol unconverted in step 3),
• 5) converting the dewatered product obtained from step 4), with addition of further alcohol, using at least one acidic catalyst in a fixed bed, in an esterification reaction,
• 6) mixing the reaction product obtained from step 3) and/or the reaction product obtained from step 5) with the remaining starting material obtained from step 1) and/or the fatty acid alkyl esters obtained from step 2).