Two‐phase flow behavior in microtube reactors during biodiesel production from waste cooking oil

Abstract

Flow patterns in the course of transesterification of waste cooking oil (WCO), sunflower oil (SFO) with water and/or oleic acid as a model of WCO, and pure SFO in the presence of a KOH catalyst in microtubes were investigated. FAME yield for the transesterification of WCO reached more than 89% in the microtube reactors with a residence time of 252 s at 333 K. The flow patterns when using WCO were changed from a liquid-liquid slug flow at the inlet region to a parallel flow at the middle region, and then to a homogeneous liquid flow at the outlet region as the reaction proceeded at 333 K. Fine droplets containing glycerol and methanol generally formed in oil slugs when using pure SFO, but were almost unobservable when using WCO. The soap produced from free fatty acids was considered to be the main factor affecting the flow patterns of WCO and SFO. V

Optimization of methyl ester production from waste cooking oil in a batch tri-orifice oscillatory baffled reactor

“…At the beginning of the reaction, oil and methanol form an immiscible liquid-liquid mixture that is mass transfer controlled due to the low solubility of these reactants. As the reaction occurs, however, the intermediates (diglycerides, monoglycerides) and methyl ester act as an emulsifier and the reaction medium is an emulsion of fine drops (or pseudo-homogeneous phase) [9][10][11][12]. In the final stage of the reaction, the products (methyl esters and glycerol), which are immiscible, for two distinct liquid phases…”

Modelling the kinetics of transesterification reaction of sunflower oil with ethanol in microreactors

“…Several studies on methanolysis using microreactors have recently been published (Sun et al, 2008(Sun et al, , 2009Wen et al, 2009;Qiu et al, 2010;Xie et al, 2012). The system is complex due to changing phase equilibria (Guan et al, 2010): two immiscible phases are present at the beginning (vegetable oil and methanol), then a single phase appears after a few minutes of reaction. Finally, two phases are obtained at the end of the reaction, majorly composed of methyl esters and glycerol.…”

On-line monitoring of the transesterification reaction carried out in microreactors using near infrared spectroscopy

“…Several works on biodiesel production using microreactors have recently been published [11][12][13][14]. The methanolysis system is complex due to changing phase equilibria [15]: two 4 immiscible phases are present at the beginning (vegetable oil and methanol), then a single phase appears after a few minutes of reaction. Finally, two phases are obtained at the end of the reaction, majorly composed of methyl esters and glycerol.…”