Biodiesel production through non-catalytic supercritical transesterification: current state and perspectives

Silva, C. da; Oliveira, J. Vladimir

doi:10.1590/0104-6632.20140312s00002616

Cited by 69 publications

(25 citation statements)

References 77 publications

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“…Better operational conditions were found at 300 °C, 20 MPa, molar ratio 1:40, and 52 min reaction, reaching 74 % esters yield. In the literature is also found the production of acrolein, acetaldehyde, acetic acid, polyglycerol, and others …”

Section: Resultsmentioning

confidence: 96%

Evaluation of the use of Gossypium hirsutum oil and supercritical ethanol for the production of ethyl esters in non‐catalytic process

et al. 2017

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The search for new sources of energy requires more and more interaction between the economical and technological viabilities associated with social development, increasing, in this manner, the interest in raw materials that generate regional development. Thus, this work analyzed the viability of ethyl esters production (biodiesel) from Gossypium hirsutum L. (cottonseed oil) without the use of a catalyst, in a continuous supercritical reactor. The reactions occurred at a tubular reactor, under 15 MPa and 20 MPa of pressure, reaction time (3.75–50 min), molar ratio of oil:alcohol (1:30–1:50), and temperature (250–400 °C). The maximum yield obtained was 75.05 % at 375 °C, under 20 or 15 MPa of pressure, molar ratio of oil:ethanol 1:40, and reaction times 30 and 40 min, respectively. A significant influence of the temperature on yield in esters was verified, but there was also thermal degradation under high temperatures, which caused a decrease in the ester's yield. The high content of polyunsaturated acids present in cotton oil possibly hampered the process of transesterification in long periods of reaction time and high temperatures.

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Section: Resultsmentioning

confidence: 96%

Evaluation of the use of Gossypium hirsutum oil and supercritical ethanol for the production of ethyl esters in non‐catalytic process

et al. 2017

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“…However, longer residence time will have trade-off relations due to multiple processes causing a decrease in FAME or FAEE composition in the product. He et al [47] evaluated the results obtained for the transesterification of soybean by varying the content of supercritical methanol (SCM) and justified that the decrease in reaction yield is the decrease in the content of unsaturated esters caused by isomerization, hydrogenation and thermal decomposition that consume such esters, especially C18:2 (linoleic) and C18:3 (linolenate), which are more susceptible to thermal decomposition in contrast to mono-unsaturated and saturated esters [48]. So, optimum reaction condition is necessary to countenance the advantage of the supercritical transesterification process over catalytic transesterification.…”

Section: Resultsmentioning

confidence: 99%

Comparison of Biodiesel Obtained from Virgin Cooking Oil and Waste Cooking Oil Using Supercritical and Catalytic Transesterification

et al. 2017

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Abstract:Comparative analysis of transesterification of virgin cooking oil (VCO) and waste cooking oil (WCO) in catalyzed and supercritical transesterification process using methanol and ethanol as solvents has been conducted in this study. The luminous point of this research was the direct comparison of catalytic and supercritical process using the ester composition obtained from virgin cooking oil and waste cooking oil transesterification. Oil to alcohol molar ratio of 1:6 and reaction condition of 65 • C and 1 bar pressure were considered for the catalytic process, while 260 • C and high pressure (65 and 75 bar for methanol and ethanol, respectively) were accounted for the supercritical process. Distinct layer separation was observed for both processes. Ester, fatty acid and glycerol composition was studied for both the upper and lower layers separately, from which 100% ester composition in the upper layer and a mixture of ester and other composition in the lower layer was obtained for the catalytic process owing to succeeding filtration and washing. However, mixture of ester (>75%) and other composition was obtained in both layers for the supercritical process where purification process was not implemented. The similarity in the result obtained demonstrates the superiority of waste cooking oil compared to virgin cooking oil, taking cost into consideration.

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“…The degradation of the fatty acid methyl ester (FAME) product typically occurs via radical chain scission with previous studies demonstrating that the degradation of methyl stearate and methyl oleate to shorter chain 1-alkenes and alkanes respectively will occur at reaction temperatures greater than 260 • C [6,15,16]. To circumvent the need for high energy input and the need for large masses of methanol chemical inputs, some studies have suggested the viability of the alternative utilisation of an integrated subcritical lipid hydrolysis and supercritical esterification (ISHSE) process.…”

Section: Introductionmentioning

confidence: 84%

Catalyst-Free Biodiesel Production Methods: A Comparative Technical and Environmental Evaluation

2018

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Abstract:In response to existing global focus on improved biodiesel production methods via highly efficient catalyst-free high temperature and high pressure technologies, this study considered the comparative study of catalyst-free technologies for biodiesel production as an important research area. In this study, therefore, catalyst-free integrated subcritical lipid hydrolysis and supercritical esterification and catalyst-free one step supercritical transesterification processes for biodiesel production have been evaluated via undertaking straight forward comparative energetic and environmental assessments. Energetic comparisons were undertaken after heat integration was performed since energy reduction has favourable effects on the environmental performance of chemical processes. The study confirmed that both processes are capable of producing biodiesel of high purity with catalyst-free integrated subcritical lipid hydrolysis and supercritical esterification characterised by a greater energy cost than catalyst-free one step supercritical transesterification processes for an equivalent biodiesel productivity potential. It was demonstrated that a one-step supercritical transesterification for biodiesel production presents an energetically more favourable catalyst-free biodiesel production pathway compared to the integrated subcritical lipid hydrolysis and supercritical esterification biodiesel production process. The one-step supercritical transesterification for biodiesel production was also shown to present an improved environmental performance compared to the integrated subcritical lipid hydrolysis and supercritical esterification biodiesel production process. This is because of the higher potential environment impact calculated for the integrated subcritical lipid hydrolysis and supercritical esterification compared to the potential environment impact calculated for the supercritical transesterification process, when all material and energy flows are considered. Finally the major contributors to the environmental outcomes of both processes were also clearly elucidated.

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Biodiesel production through non-catalytic supercritical transesterification: current state and perspectives

Cited by 69 publications

References 77 publications

Evaluation of the use of Gossypium hirsutum oil and supercritical ethanol for the production of ethyl esters in non‐catalytic process

Evaluation of the use of Gossypium hirsutum oil and supercritical ethanol for the production of ethyl esters in non‐catalytic process

Comparison of Biodiesel Obtained from Virgin Cooking Oil and Waste Cooking Oil Using Supercritical and Catalytic Transesterification

Catalyst-Free Biodiesel Production Methods: A Comparative Technical and Environmental Evaluation

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