Effects of epoxidation on the thermal oxidative stabilities of fatty acid esters derived from palm olein

Gan, L. H.; Ooi, K. S.; Gan, Lu; Goh, S. H.

doi:10.1007/bf02636085

Cited by 32 publications

(19 citation statements)

References 5 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Eventually, the rate of disappearance of hydroperoxides exceeds formation, causing PV to decrease from a maximum. This phenomenon was observed previously for SME (26), methyl esters of palm olein (27), and various alkyl esters of safflower oil (28).…”

Section: Resultssupporting

confidence: 58%

Effect of oxidation under accelerated conditions on fuel properties of methyl soyate (biodiesel)

Dunn

2002

J Americ Oil Chem Soc

152

View full text Add to dashboard Cite

Biodiesel derived from transesterification of soybean oil and methanol is an attractive alternative fuel for combustion in direct-injection compression ignition (diesel) engines. During long-term storage, oxidation due to contact with air (autoxidation) presents a legitimate concern with respect to maintaining fuel quality of biodiesel. This work examines the effects of oxidation under controlled accelerated conditions on fuel properties of methyl soyate (SME). SME samples from four separate sources with varying storage histories were oxidized at elevated temperature under a 0.5 standard cm 3 /min air purge and with continuous stirring. Results showed that reaction time significantly affects kinematic viscosity (ν). With respect to increasing reaction temperature, ν, acid value (AV), PV, and specific gravity (SG) increased significantly, whereas cold flow properties were minimally affected for temperatures up to 150°C. Antioxidants TBHQ and α-tocopherol showed beneficial effects on retarding oxidative degradation of SME under conditions of this study. Results indicated that ν and AV have the best potential as parameters for timely and easy monitoring of biodiesel fuel quality during storage.Paper no. J10163 in JAOCS 79, 915-920 (September 2002).KEY WORDS: Acid value, antioxidant, diesel fuels, fatty acid methyl esters, kinematic viscosity, oxidative stability, peroxide value, soybean oil.Biodiesel (FA monoalkyl esters derived from vegetable oil or animal fat) is nearly ideal as an alternative fuel or fuel extender for combustion in direct-injection compression ignition (diesel) engines. Biodiesel has many fuel properties, including viscosity, gross heat of combustion, and cetane number, that are comparable to those of No. 2 diesel fuel (1-4). The lubricity characteristics of biodiesel allow improvement of antiwear properties in blends with low-sulfur No. 2 diesel fuel (5). In blends with conventional diesel fuel, biodiesel reduces exhaust emissions including particulate matter, hydrocarbons, polycyclic aromatic hydrocarbons, sulfur dioxide, carbon monoxide, and smoke (1,4,6-11). Biodiesel has a negative carbon dioxide balance and produces more than twice the energy required to create it (6,9). The effects of oxidative degradation caused by contact with ambient air (autoxidation) during long-term storage present a legitimate concern in terms of maintaining fuel quality of biodiesel. Biodiesel derived from transesterification of soybean oil and methanol is a mixture of unsaturated and saturated long-chain (C 18 ) FA esters. Methyl soyate (SME) is composed of 80-85 wt% total unsaturated esters and has a relatively high degree of polyunsaturation. Unsaturated compounds are significantly more reactive to oxidation than saturated compounds; increasing the degree of unsaturation further increases reactivity (12).Oxidative stability is not recognized as a parameter in the American Society for Testing and Materials (ASTM) provisional fuel standard guideline for biodiesel, PS121 (13), because cumulative effects of autoxida...

show abstract

Section: Resultssupporting

confidence: 58%

Effect of oxidation under accelerated conditions on fuel properties of methyl soyate (biodiesel)

Dunn

2002

J Americ Oil Chem Soc

152

View full text Add to dashboard Cite

show abstract

“…Although not listed as a parameter in D 6751, increasing PV increases CN, a parameter in the fuel specification that can affect ignition delay time (21,22). Although early stages of degradation increase PV, extensive degradation from decomposition of hydroperoxides eventually decreases PV, as reported previously for SME (16,17), methyl esters of palm olein (23), and various alkyl esters of safflower oil (24). Other parameters within D 6751 that may be affected by oxidative degradation include flash point, water and sediment, copper strip corrosion, carbon residue, and distillation temperature at reduced pressure.…”

mentioning

confidence: 64%

Oxidative stability of soybean oil fatty acid methyl esters by oil stability index (OSI)

Dunn

2005

J Americ Oil Chem Soc

View full text Add to dashboard Cite

Biodiesel, an alternative diesel fuel derived from transesterification of vegetable oils or animal fats, is composed of saturated and unsaturated long-chain FA alkyl esters. During long-term storage, oxidation caused by contact with air (autoxidation) presents a legitimate concern with respect to monitoring and maintaining fuel quality. Extensive oxidative degradation may compromise quality by adversely affecting kinematic viscosity, acid value, or PV. This work examines the oil stability index (OSI) as a parameter for monitoring the oxidative stability of soybean oil FAME (SME). SME samples from five separate sources and with varying storage and handling histories were analyzed for OSI at 60°C using an oxidative stability instrument. Results showed that OSI may be used to measure relative oxidative stability of SME samples as well as to differentiate between samples from different producers. Although addition of α-tocopherol or TBHQ increased OSI, responses to these antioxidants varied with respect to SME sample. Variations in response to added antioxidant were attributed to aging and other effects that may have caused oxidative degradation in samples prior to acquisition for this study. Results showed that OSI was more sensitive than iodine value in detecting the effects of oxidative degradation in its early stages when monitoring SME during storage. FIG. 1.Oxidative stability instrument data (conductivity vs. time) for one replicate oil stability index (OSI) measurement each for neat SME-A and SME-A treated with 1000 ppm α-tocopherol and 500 ppm TBHQ. Results for each curve were: OSI = 9.45 h for SME-A, 23.55 h for α-tocopherol, and 53.75 h for TBHQ. SME = soybean oil FAME. OXIDATIVE STABILITY OF BIODIESEL 385 JAOCS, Vol. 82, no. 5 (2005) FIG. 2. Effect of antioxidant loading on OSI of SME-D. See Figure 1 for abbreviations.

show abstract

“…This stage is defined as the induction period. Following the induction period, oxidation reactions proceed, decomposition of primary oxidation products (hydroperoxides) yield a mixture of secondary products including short-chain carboxylic acids, ketones, aldehydes, mono-and dihydroxy compounds and also polymers or sediments [28]. As a result, after induction period, not only the key properties of biodiesel degrade quickly, but also engine operation problems come forth.…”

Section: Induction Period As Obtained By Extrapolated Methodsmentioning

confidence: 99%

Kinetics on the oxidation of biodiesel stabilized with antioxidant

Xin

Imahara

Saka

2009

Fuel

141

View full text Add to dashboard Cite

Oxidation stability of safflower biodiesel stabilized with propyl gallate whose concentration spreads from 0-5,000ppm was studied by Rancimat method at temperatures from 100-120 o C. It was consequently demonstrated that the induction period of biodiesel increases with the increase of antioxidant concentration and decreases with increase of temperature. Kinetics on its oxidation was described by the first order rate law with an accuracy higher than 0.98. The reaction rate of propyl gallate consumed in safflower biodiesel obtained from the experiment fits well with Arrhenius equation and the activation energy obtained from Arrhenius equation was 97.02kJ/mol. Logarithm of induction periods determined by Rancimat method with various antioxidantconcentrations shows a linear relation with temperatures. It was, consequently, found that the Rancimat method for the oxidation stability determination shows an approximate correlation between storage stability and Rancimat induction period. The Rancimat method cannot directly measure the overall storage stability of fuels, since other conditions such as presence of water, microbial contamination, storages conditions etc. would affect fuel quality during storage.

show abstract

Effects of epoxidation on the thermal oxidative stabilities of fatty acid esters derived from palm olein

Cited by 32 publications

References 5 publications

Effect of oxidation under accelerated conditions on fuel properties of methyl soyate (biodiesel)

Effect of oxidation under accelerated conditions on fuel properties of methyl soyate (biodiesel)

Oxidative stability of soybean oil fatty acid methyl esters by oil stability index (OSI)

Kinetics on the oxidation of biodiesel stabilized with antioxidant

Contact Info

Product

Resources

About