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oleic acid are controlled by three dominant complementary genes. A study combines
the standard intrinsic genome sequences of high oleic acid characteristics and obtains
self-flowering high oleic acid plants from several generations of backcross breeding
programs [11]. Oil crops with high oleic acid content have been highly valued.
The content of oleic acid in common sunflower seed oil is about 30%, but that in
high oleic acid plant oils, which are cultivated by modern biotechnology, oleic acid
content is more than 90% [24]. Genetic engineering is an effective approach to further
improve the lubricity performances of high oleate plant oils. By expressing a fatty
acid hydroxylase gene from castor in canola, oil containing up to 16% hydroxy fatty
acid can be produced in a high oleate background. Results show that the introduction
of hydroxy fatty acids significantly increases the viscosity and oxidation stability of
plant oils [14].
However, the biological modification of plant oil will inevitably meet the problems
of biological genetic stability and long research cycle. Industrial manufacture requires
a stable and effective means to modify plant oil in order to achieve the purpose of
applying to the field of lubrication.
7.2.2.3 Chemical Modification of Bio-Lubricant Base Oil
Although biological modification can increase the content of oleic acid and therefore
improve the overall oxidation stability and low-temperature fluidity, it has the problems of genetic stability. The chemical modification method has higher biological
safety, better industrial processing basis and product performances. The vulnerable parts of plant oil molecules include double bond, allyl carbon, etc. Chemical
modification is mainly directed against these vulnerable parts [24].
At present, the research on chemical modification of plant oil is mainly
focused on improving its degree of saturation and branching. The main ideas of chemical modification are hydrogenization, polymerization, transesterification, esterification, and isomerization. The selective hydrogenation, oligomerization, and cyclization of plant oil can reduce the unsaturated components in plant oil, that is, to
improve the service life of the oil, and have no obvious effects on its low-temperature
performance [13].
Selective Hydrogenation
Selective hydrogenation has great application prospects in the synthesis of lubricating oil. In the process of hydrogenation, if the unsaturated fatty acids are completely
converted to saturated fatty acids, which are solid under normal conditions, the oxidation stability can be improved, while the low-temperature fluidity becomes worse.
It is generally believed that the unsaturated fatty acid triglyceride containing one
double bond has good oxidation stability and low-temperature fluidity. Therefore,
selective catalytic hydrogenation, to a certain extent, reduces the unsaturation, and is
Y. Cao et al.
oleic acid are controlled by three dominant complementary genes. A study combines
the standard intrinsic genome sequences of high oleic acid characteristics and obtains
self-flowering high oleic acid plants from several generations of backcross breeding
programs [11]. Oil crops with high oleic acid content have been highly valued.
The content of oleic acid in common sunflower seed oil is about 30%, but that in
high oleic acid plant oils, which are cultivated by modern biotechnology, oleic acid
content is more than 90% [24]. Genetic engineering is an effective approach to further
improve the lubricity performances of high oleate plant oils. By expressing a fatty
acid hydroxylase gene from castor in canola, oil containing up to 16% hydroxy fatty
acid can be produced in a high oleate background. Results show that the introduction
of hydroxy fatty acids significantly increases the viscosity and oxidation stability of
plant oils [14].
However, the biological modification of plant oil will inevitably meet the problems
of biological genetic stability and long research cycle. Industrial manufacture requires
a stable and effective means to modify plant oil in order to achieve the purpose of
applying to the field of lubrication.
7.2.2.3 Chemical Modification of Bio-Lubricant Base Oil
Although biological modification can increase the content of oleic acid and therefore
improve the overall oxidation stability and low-temperature fluidity, it has the problems of genetic stability. The chemical modification method has higher biological
safety, better industrial processing basis and product performances. The vulnerable parts of plant oil molecules include double bond, allyl carbon, etc. Chemical
modification is mainly directed against these vulnerable parts [24].
At present, the research on chemical modification of plant oil is mainly
focused on improving its degree of saturation and branching. The main ideas of chemical modification are hydrogenization, polymerization, transesterification, esterification, and isomerization. The selective hydrogenation, oligomerization, and cyclization of plant oil can reduce the unsaturated components in plant oil, that is, to
improve the service life of the oil, and have no obvious effects on its low-temperature
performance [13].
Selective Hydrogenation
Selective hydrogenation has great application prospects in the synthesis of lubricating oil. In the process of hydrogenation, if the unsaturated fatty acids are completely
converted to saturated fatty acids, which are solid under normal conditions, the oxidation stability can be improved, while the low-temperature fluidity becomes worse.
It is generally believed that the unsaturated fatty acid triglyceride containing one
double bond has good oxidation stability and low-temperature fluidity. Therefore,
selective catalytic hydrogenation, to a certain extent, reduces the unsaturation, and is