Stability of ethyl esters from soybean oil exposed to high temperatures in supercritical ethanol

-This study evaluated the potential of macauba pulp oil (MPO) as a feedstock for continuous ester production using ethanol under pressurized conditions. Experiments were performed in order to obtain data for the effect of process variables on ethyl ester (FAEE) and free fatty acid (FFA) conversion in a catalyst-free process. From the results, it appears that the MPO to ethanol mass ratio and the pressure were the variables with more favorable effect on the evaluated response variables. The addition of n-hexane caused an increase in the production of esters; however, this had a negative effect on FFA conversion. The addition of water was unfavorable for oil processing with high acidity. In this process, esterification and transesterification occur simultaneously, and the high FFA content in MPO provides high yields (85 wt% of esters; 93% FFA conversion) at low temperature, since the esterification reaction rate is higher than the transesterification. The decomposition of fatty acids was evaluated and levels <5% were observed under the evaluated experimental conditions.

Section: Comparison With the Literaturesupporting

confidence: 90%

Assessment of process variables on the use of macauba pulp oil as feedstock for the continuous production of ethyl esters under pressurized conditions

Colonelli

Trentini

Santos

et al. 2017

“…As a polyunsaturated fatty acid containing two double bonds, ethyl linoleate (C18:2) is increasingly unstable at higher temperatures compared with the monounsaturated and saturated ones. A similar behavior was likewiseobserved in the biodiesel production of soybean with SCE (Vieitez et al, 2011), ethyl linoleate (C18:2) and ethyl linolenate (C18:3) drastically reduce relative to ethyl palmitate (C16:0) at the highest temperature of 370 °C. The thermal cracking products are comprised of small compounds, i.e., alkane hydrocarbons in the range of C9-C10 as shown in Table 4 (see Section Reaction between glycerol and supercritical ethanol).…”

Section: Effect Of Reaction Timessupporting

confidence: 77%

An entirely renewable biofuel production from used palm oil with supercritical ethanol at low molar ratio

Sakdasri

Sawangkeaw

Ngamprasertsith

2017

-The biofuel production from used palm oil (UPO) using supercritical ethanol (SCE) at low molar ratio was investigated in order to produce an entirely renewable fuel. The effects of the reaction time and ethanol to oil molar ratio were considered from 0.5 to 10 min and 6:1 to 18:1, respectively. The optimal parameters were 10 min and a 12:1 molar ratio, representing a remarkable reduction from 42:1 for the conventional SCE process. Because of the high operating temperature, the triglycerides conversion rate reached 99%, and the glycerides content met the international specification for biodiesel. However, an ester content of 70% was obtained at optimal conditions. The side reaction between glycerol and ethanol demonstrated a positive effect in increasing fuel yield by 8.15%. The product can be considered an alternative biofuel instead of biodiesel.

“…A study by Vieitez et al (2011a) showed that the lowest decomposition of ethyl esters was reached with a water concentration of 10 wt%. Vieitez et al (2009), in the transesterification of soybean oil under supercritical conditions, reported at 598 K, 1:40 (oil:ethanol molar ratio), 20 MPa and 52.5 min of reaction, about 17 wt% decomposition without the addition of water and 11 wt% decomposition with a water concentration of 10 wt%.…”

Section: Effect Of Water Additionmentioning

confidence: 99%

“…Indeed, with longer residence times and without water addition, 9.7 wt% decomposition at 573 K (Figure 5(a)) increased to 15 wt% at 598 K. Vieitez et al (2009), in the transesterification of soybean oil using supercritical ethanol in continuous mode, reported about 30 wt% and 52 wt% decomposition at 573 K and 598 K, respectively, at 20 MPa, an oil:ethanol molar ratio of 1:40 and 52.5 min of reaction time. Vieitez et al (2011a) evaluated the exposure of FAEE from soybean oil for different periods under supercritical conditions and reported about 5 wt% decomposition for ethyl esters at 573 K, 20 MPa, 52.5 min and an FAEE:ethanol molar ratio of 3:40. For the transesterification of soybean oil in a batch reactor, Olivares-Carrillo and Quesada-Medina (2011) reported decomposition values of about 18 wt% at 573 K and 9 wt% at 598 K, for a reaction conducted at 20 MPa, with an oil:methanol molar ratio of 1:43 and 90 min of reaction time.…”

Section: 52mentioning

confidence: 99%

Continuous catalyst-free production of esters from Jatropha curcas L. oil under supercritical ethanol

Silva

Colonelli

Silva

et al. 2014

-In the present study, the transesterification of Jatropha oil in a continuous catalyst-free process using supercritical ethanol was investigated. Experiments were performed in a packed-bed tubular reactor by studying the effect on the reaction of temperature, pressure, water and cosolvent (n-hexane) concentrations, keeping the oil:ethanol mass ratio fixed at 1:1 for different residence times. The results demonstrated that temperature and pressure had a positive effect on fatty acid ethyl ester (FAEE) production and it was observed that the free fatty acids present in vegetable oil promote faster reaction kinetics due to simultaneous esterification and transesterification reactions. The addition of water and a cosolvent increased the FAEE yields at 573 K and 20 MPa. Within the experimental ranges investigated, water and the cosolvent decreased the decomposition of fatty acids. Appreciable reaction yields (~90 wt%) were achieved at 573 K, 20 MPa, with an oil:ethanol mass ratio of 1:1 and 10 wt% water.