The oxidative stability of FAME in the model Crankcase environment
File(s)
Author(s)
Hall, James
Type
Thesis
Abstract
The use of biodiesel has increased in recent years due to the implementation of
governmental policies driven by environmental, economic and political reasons. Biodiesel is
composed of fatty acid methyl esters (FAME), which can be derived from plant, marine and
animal sources. There have been reports of some potential problems associated with
biodiesel use in modern diesel engines, with lubricant dilution by blended biodiesel fuels
leading to accumulation of FAME in the oil sump in the crankcase.
This project focuses on the design and implementation of an experimental model based on
the Rancimat apparatus that can simulate certain aspects of the FAME degradation
chemistry occurring in the crankcase and oil sump. An analysis procedure to compliment the
experimental model is applied to carry out product distribution analysis on a series of (C18)
model FAME, identifying and quantifying the oxidation products formed under the
experimental conditions, where epoxides are the major monomeric degradation.
Some oxidation kinetic parameters have been investigated using biodiesel samples, with
noticeable differences in oxidation rates found when FAME are oxidised individually and
when in mixtures. Kinetic factors of FAME and model base oil in single and multi-component
systems have also been investigated, with the base oil displaying good oxidative stability in
mixtures as well as on its own
The influence of antioxidants on stabilising various model systems has shown synergistic
effects. Combinations of primary and secondary antioxidants have displayed good synergy,
with the suppression of the rate of hydroperoxide formation by primary antioxidants
enhancing the effectiveness of the secondary antioxidant. Primary antioxidants have been
observed to affect the onset of oxidation, whilst secondary antioxidants decrease the
hydroperoxide and epoxide, but increase the alcohol yields as a result of autoxidation.
governmental policies driven by environmental, economic and political reasons. Biodiesel is
composed of fatty acid methyl esters (FAME), which can be derived from plant, marine and
animal sources. There have been reports of some potential problems associated with
biodiesel use in modern diesel engines, with lubricant dilution by blended biodiesel fuels
leading to accumulation of FAME in the oil sump in the crankcase.
This project focuses on the design and implementation of an experimental model based on
the Rancimat apparatus that can simulate certain aspects of the FAME degradation
chemistry occurring in the crankcase and oil sump. An analysis procedure to compliment the
experimental model is applied to carry out product distribution analysis on a series of (C18)
model FAME, identifying and quantifying the oxidation products formed under the
experimental conditions, where epoxides are the major monomeric degradation.
Some oxidation kinetic parameters have been investigated using biodiesel samples, with
noticeable differences in oxidation rates found when FAME are oxidised individually and
when in mixtures. Kinetic factors of FAME and model base oil in single and multi-component
systems have also been investigated, with the base oil displaying good oxidative stability in
mixtures as well as on its own
The influence of antioxidants on stabilising various model systems has shown synergistic
effects. Combinations of primary and secondary antioxidants have displayed good synergy,
with the suppression of the rate of hydroperoxide formation by primary antioxidants
enhancing the effectiveness of the secondary antioxidant. Primary antioxidants have been
observed to affect the onset of oxidation, whilst secondary antioxidants decrease the
hydroperoxide and epoxide, but increase the alcohol yields as a result of autoxidation.
Version
Open Access
Date Issued
2012-10
Date Awarded
2013-04
Copyright Statement
Attribution NoDerivatives 4.0 International Licence (CC BY-ND)
Advisor
Davies, Rob
Long, Nicholas
Publisher Department
Chemistry
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)