Thermal stability of biodiesel in supercritical methanol

Imahara, Hiroaki; Minami, Eiji; Hari, Shusaku; Saka, Shiro

doi:10.1016/j.fuel.2007.04.003

Cited by 260 publications

(158 citation statements)

References 6 publications

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“…Ethyl palmitate (C16:0) and ethyl oleate (C18:1) were observed as the main components, which corresponded to the primary composition in Table 1. This observation indicates that the initially formed FAEEs can degrade with excessive reaction times at high temperature, as previously reported in the literature (Sawangkeaw et al, 2011;Imahara et al, 2008). In addition, it is evident that ethyl linoleate (C18:2) is more rapidly degraded, with a decline starting at 5 min of reaction time.…”

Section: Effect Of Reaction Timessupporting

confidence: 86%

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

Sakdasri

Sawangkeaw

Ngamprasertsith

2017

Braz. J. Chem. Eng.

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-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.

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Section: Effect Of Reaction Timessupporting

confidence: 86%

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

Sakdasri

Sawangkeaw

Ngamprasertsith

2017

Braz. J. Chem. Eng.

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“…Imahara et al reported that the breakdown of polyunsaturated fatty acids such as linolenic acid is remarkable in temperature higher than 300°C [7]. Therefore, it is presumed that the less yield of FAME at 380°C compared with 350°C is due to the breakdown of unsaturated fatty acids at the higher temperature.…”

Section: Trans-esterification Of Triglycerides With Methyl Acetatementioning

confidence: 99%

A new process for catalyst-free production of biodiesel using supercritical methyl acetate

Saka

Isayama

2009

Fuel

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189

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Production of glycerol is unavoidable in the conventional processes for biodiesel fuel (BDF) production. In this research, therefore, we investigated conversion of rapeseed oil to fatty acid methyl esters (FAME) and triacetin by processing of supercritical methyl acetate. As a result, it was discovered that the trans-esterification reaction of triglycerides with methyl acetate can proceed without catalyst under supercritical conditions, generating FAME and triacetin. In order to study the effect of the triacetin addition to FAME, its effect was investigated on various fuel characteristics. It was, consequently, discovered that there were no adverse effects on the main fuel characteristics when the molar ratio of methyl oleate to triacetin was 3:1, corresponding to the theoretically derived mole ratio from the trans-esterification reaction of rapeseed oil with methyl acetate. Moreover, the addition of triacetin to methyl oleate improved the pour point and triacetin has high oxidation stability. Therefore, by defining BDF as a mixture of methyl oleate with triacetin, we can obtain an improved yield of 105% of BDF by the supercritical methyl acetate, in excess of the yield of the conventional process.

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“…Different studies report the reasons for this fact - He et al (2007) evaluated the results obtained for the transesterification of soybean oil in supercritical methanol and concluded that the reason for 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) that are more susceptible to thermal decomposition compared to mono-unsaturated and saturated esters. Imahara et al (2008) evaluated the thermal stability of different samples of biodiesel and fatty acid esters under different conditions and found that thermal degradation is more pronounced for the unsaturated esters above 573 K and 19 MPa and thermal stability of saturated esters is also affected. In order to evaluate the existence of thermal decompostion in the soybean oil transesterification with supercritical methanol, Olivares-Carrillo and Quesada-Medina (2011b) reported the evolution of the molar ratio between methyl linoleate and methyl palmitate (the main unsaturated and saturated FAMEs generated, respectively); the results showed that the molar ratio between these FAMEs decreased with the reaction time at 573 K/26 MPa and above: the higher the temperature, the lower the molar ratio.…”

Section: Decomposition Of Fatty Acidsmentioning

confidence: 99%

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

Silva

Oliveira

2014

Braz. J. Chem. Eng.

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-The inconveniences of the conventional method for biodiesel production by alkaline catalysis suggests research towards alternative methods, with the non-catalytic transesterification using an alcohol at supercritical conditions proposed as a promising technique for biodiesel production. The so-called supercritical method (SCM) has powerful advantages over conventional techniques, such as fast reaction rates, feedstock flexibility, production efficiency and environmentally friendly benefits. However, application of this methodology has some limitations, like operating conditions (elevated temperature and pressure and higher amounts of alcohol), which result in high energy costs and degradation of the products generated. In this review paper the state of the art in relation to the use of the SCM for biodiesel production is reported and discussed, describing the characteristics of the method, the influence of operational parameters on the ester yield, patents available in the field and the perspectives for application of the technique.

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Thermal stability of biodiesel in supercritical methanol

Cited by 260 publications

References 6 publications

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

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

A new process for catalyst-free production of biodiesel using supercritical methyl acetate

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

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