experiments used and analyze their effectiveness by
looking at the product yields and the models’ ability
to recycle the catalysts used.
3 RESULTS AND DISCUSSIONS
The 1980s saw the introduction of reformulated gasoline (a composite of regular gasoline and oxygenated
compounds) in the US in response to increasing public
awareness and regulatory actions aimed at improving the quality of air in large urban areas. And, while
methyl tert-butyl ether (MTBE) was the most popular
additive from the onset, because of its cost effectiveness used by refineries to reduce production cost of
Reformulated Gasoline (RFG) whose classification as
a hazardous material by the International Agency of
Research on Cancer (IARC) in 2000 resulted in it being
phased out, and created opportunities for the development and penetration of renewable fuel substitutes,
such as ethanol. However, despite ethanol experiencing a surge in popularity, investment and development
since then, many studies have raised concerns about
its practicality and sustainability because of its overreliance on corn (for carbohydrate fermentation), and
the infancy of its production from cellulosic materials
(Mota et al., 2010; Talebian-Kiakalaieh et al., 2018).
While glycerol’s triol constitution with more than half
its weight in oxygen atoms makes it a good base
for the development of oxygenated fuel additives, its
polar properties that make it insoluble in hydrocarbons
coupled with its high boiling point make it unsuitable for blending with gasoline. However, its ketals
and acetals (and those formed through reactions with
acetone (illustrated in Scheme 1) and formaldehyde
(illustrated in Scheme 2) in particular) form better
combustion enhancers for gasoline (Mota et al., 2010).
Figure 1. Scheme 1. Reaction of glycerol with acetone
under heterogeneous acid catalysis (Mota et al., 2010).
Figure 1. Scheme 2. Reaction of glycerol with formaldehyde solution under heterogeneous acid catalysis (Mota et al.,
2010).
Ketalization processes between glycerol and acetone can also result in the production of 2,2-dimethyl1, 3-dioxolane-4-methanol (also known as solketal)
when acid is used to catalyze the reaction as illustrated
in the scheme below (Talebian-Kiakalaieh et al., 2018).
3.1 Glycochemistry
The processes through which glycerol is processed into
value added products, such as the acetalization process
used to produce solketal, glycerol acetal and glycerol
formal which are used as solvents, plasticizers, surfactants, disinfectants, and flavoring agents, is known as
glycerochemistry (Vinicius Rossa et al., 2019). However, solketal production is so far the most economic
and promising use of glycerol because of the versatility of its uses and applications across a variety of
industries. In combustion, it is used as an oxygenate
fuel additive and helps to reduce soot by increasing
the octane number of fuels, therefore, increasing overall combustion (efficiency especially in gasoline), and
reduces the incidence of fuel crystallization by improving the cold flow properties of fuels. In manufacturing,
solketal’s versatility as a solvent and a plasticizer make
it an integral component in the production of polymers,
and its versatility solubilizing and suspension agent
make it an important component in the manufacture
of drugs and in food processing. Solketal’s sustainability on the environment despite its higher aquatox
fish test LC50 level of 3162 ppm also increases its suitability for more uses and applications (Fatimah et al.,
2019; Ilgen, Yerlikaya, & Akyurek, 2017; Luma Sh.
Al-Saadi, Eze, & Harvey, 2019; Pandian Manjunathan,
Sanjeev P. Maradur, A.B. Halgeri, & Shanbhag, 2014;
Talebian-Kiakalaieh et al., 2018; Vinicius Rossa et al.,
2019).
Figure 2. Transformation routes of glycerol into higher
added value products (Vinicius Rossa et al., 2019).
In the ketalization process, the synthesis of glycerol
and ketones produces two branched oxygenates, solketal (2,2-dimethyl- [1,3]-dioxan-4-yl methanol) and
2,2-dimethyl- [1,3] dioxane-5-ol, while substituting
acetone for ketones increases the reaction’s selectivity
for solketal molecules, which have a five-membered
257
looking at the product yields and the models’ ability
to recycle the catalysts used.
3 RESULTS AND DISCUSSIONS
The 1980s saw the introduction of reformulated gasoline (a composite of regular gasoline and oxygenated
compounds) in the US in response to increasing public
awareness and regulatory actions aimed at improving the quality of air in large urban areas. And, while
methyl tert-butyl ether (MTBE) was the most popular
additive from the onset, because of its cost effectiveness used by refineries to reduce production cost of
Reformulated Gasoline (RFG) whose classification as
a hazardous material by the International Agency of
Research on Cancer (IARC) in 2000 resulted in it being
phased out, and created opportunities for the development and penetration of renewable fuel substitutes,
such as ethanol. However, despite ethanol experiencing a surge in popularity, investment and development
since then, many studies have raised concerns about
its practicality and sustainability because of its overreliance on corn (for carbohydrate fermentation), and
the infancy of its production from cellulosic materials
(Mota et al., 2010; Talebian-Kiakalaieh et al., 2018).
While glycerol’s triol constitution with more than half
its weight in oxygen atoms makes it a good base
for the development of oxygenated fuel additives, its
polar properties that make it insoluble in hydrocarbons
coupled with its high boiling point make it unsuitable for blending with gasoline. However, its ketals
and acetals (and those formed through reactions with
acetone (illustrated in Scheme 1) and formaldehyde
(illustrated in Scheme 2) in particular) form better
combustion enhancers for gasoline (Mota et al., 2010).
Figure 1. Scheme 1. Reaction of glycerol with acetone
under heterogeneous acid catalysis (Mota et al., 2010).
Figure 1. Scheme 2. Reaction of glycerol with formaldehyde solution under heterogeneous acid catalysis (Mota et al.,
2010).
Ketalization processes between glycerol and acetone can also result in the production of 2,2-dimethyl1, 3-dioxolane-4-methanol (also known as solketal)
when acid is used to catalyze the reaction as illustrated
in the scheme below (Talebian-Kiakalaieh et al., 2018).
3.1 Glycochemistry
The processes through which glycerol is processed into
value added products, such as the acetalization process
used to produce solketal, glycerol acetal and glycerol
formal which are used as solvents, plasticizers, surfactants, disinfectants, and flavoring agents, is known as
glycerochemistry (Vinicius Rossa et al., 2019). However, solketal production is so far the most economic
and promising use of glycerol because of the versatility of its uses and applications across a variety of
industries. In combustion, it is used as an oxygenate
fuel additive and helps to reduce soot by increasing
the octane number of fuels, therefore, increasing overall combustion (efficiency especially in gasoline), and
reduces the incidence of fuel crystallization by improving the cold flow properties of fuels. In manufacturing,
solketal’s versatility as a solvent and a plasticizer make
it an integral component in the production of polymers,
and its versatility solubilizing and suspension agent
make it an important component in the manufacture
of drugs and in food processing. Solketal’s sustainability on the environment despite its higher aquatox
fish test LC50 level of 3162 ppm also increases its suitability for more uses and applications (Fatimah et al.,
2019; Ilgen, Yerlikaya, & Akyurek, 2017; Luma Sh.
Al-Saadi, Eze, & Harvey, 2019; Pandian Manjunathan,
Sanjeev P. Maradur, A.B. Halgeri, & Shanbhag, 2014;
Talebian-Kiakalaieh et al., 2018; Vinicius Rossa et al.,
2019).
Figure 2. Transformation routes of glycerol into higher
added value products (Vinicius Rossa et al., 2019).
In the ketalization process, the synthesis of glycerol
and ketones produces two branched oxygenates, solketal (2,2-dimethyl- [1,3]-dioxan-4-yl methanol) and
2,2-dimethyl- [1,3] dioxane-5-ol, while substituting
acetone for ketones increases the reaction’s selectivity
for solketal molecules, which have a five-membered
257