Biodiesel production from high FFA feedstocks with a novel chemical multifunctional process intensifier

Abstract

Biodiesel production is generally accomplished by the transesterification of vegetable oils and animal fats with a short chain alcohol (mostly methanol) in the presence of an alkali catalyst (mostly potassium or sodium hydroxide) in continuous stirred tank reactors. This chemical reaction requires heating at around 60°C and usually takes about 60 to 120 min. When using oil/fat feedstocks containing high free fatty acids (FFA) contents, acid esterification is often required to prevent the saponification of fatty acids with the base catalyst in the subsequent transesterification. These impose high energy and time requirements. In the present study, we introduce a novel chemical multifunctional process intensifier involving a reaction zone with magnetostrictive cylindrical particles (agents) subjected to an oscillating electromagnetic field for efficient biodiesel production from high FFA content feedstocks. The results obtained revealed that the esterification and transesterification reactions could be substantially intensified under the action of an oscillating electromagnetic field that forces magnetostrictive agents to rapidly vibrate and intensify the mixing of the reagents. Complete conversion of oils was observed at an extremely short reaction time (30–180 s) and at the ambient temperature. Using the investigated technology, oil/fat mixtures with higher initial FFA contents, i.e., ~9%, could be used in alkali catalyzed transesterification processes compared with conventional reactors (capable of handling FFA contents of ~2.5%).