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

Alexandros Litinas,Aris Faliakis,Savas Geivanidis,Ivan Gandzha,Mykola Dmytriyuk,Oleksandr Puhach,Yuri Zabulonov,Yannis Courouclis,Zissis Samaras,August Keder,Volodymyr Krasnoholovets

doi:10.18331/brj2020.7.2.5

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%).

Highlights

Production of renewable fuels and biodiesel in particular has increased during the last years due to the need for alternative and cleaner sources of energy
We introduce a novel chemical multifunctional process intensifier involving a reaction zone with magnetostrictive cylindrical particles subjected to an oscillating electromagnetic field for efficient biodiesel production from high free fatty acids (FFA) content feedstocks
The recommended FFA content of oils used in the transesterification process is 1 wt% (Bradshaw and Meuly, 1944; Feuge and Gros, 1949; Ma et al, 1998), industrial experiences indicate that oils/fats of up to 2.5 wt% FFA content can still be used in the transesterification process

Summary

Introduction

Production of renewable fuels and biodiesel in particular has increased during the last years due to the need for alternative and cleaner sources of energy. There are various processes for biodiesel production including homogeneous alkali (base) catalyzed transesterification (Ma and Hanna, 1999; Jeong et al, 2004), homogenous acid catalyzed transesterification (Fukuda et al, 2001), heterogeneous base or acid catalyzed transesterification (Furuta et al, 2006), enzyme catalyzed transesterification (Nelson et al, 1996; Shimada et al, 1999), supercritical alcohol transesterification (Vyas et al, 2010), etc. The transesterification of oils is a reaction where alcohol (usually methanol) reacts with triglycerides contained in the oil feedstock in the presence of a catalyst (usually alkali) producing fatty acid esters and glycerin. Transesterification is mainly affected by molar ratio of oil or fat to alcohol, catalyst, reaction time, temperature, free fatty acids (FFA) content, and water content of the feedstock (Freedman et al, 1984; Ma and Hanna, 1999). Various studies demonstrated that water content should be less than 0.06% and FFA less than 0.5% in order to get a desirable conversion (Bradshaw and Meuly, 1944; Freedman et al, 1984; Ma et al, 1998)

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