Critical Literature Review on the Hydrothermal Conversion of Vegetable Oil to Jet Fuel Range Alkanes

Literature review 1
CRITICAL LITERATURE REVIEW ON THE HYDROTHERMAL CONVERSION OF
VEGETABLE OIL TO JET FUEL RANGE ALKANES
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Literature review 2
Hydrolysis
Hydrolysis has been significantly adopted in the attempt to obtain fatty acids from the
vegetable oil. To ensure the accessibility and availability of cellulose, the best performance
recommendation is carbonic acid and alkaline extraction. The carbon dioxide and sulphuric
acid is always added in order to limit the production of inhibitors as well as improvement of
the hemicellulose (Wang et al., 2015). This is contrary to the use of a steam explosion, as it
does not completely break down the lignin carbohydrate mixture. By extension, numerous
strategies have been investigated to aimed at detoxification of lignocellulose hydrolysates,
and the best approach with promising results is the hydrolysis of myco-LB. this assists in
total sugar recovery and also prevent the fermentation inhibitors. A number of methods,
operational conditions as well as catalysts have proved to offer the optimum grounds for the
process f extraction of free fatty acids from the vegetable oils. The batch mode proved to
offer the best yield results when hydrolysis is analysed. For instance, due to the constant
volume within the reactor, the reaction time was similar for all reactants. It indicated more
complete reactions with minimal degradation of the by-products. Lipase has been used as
biocatalysts (triacylglycerol hydrolase, EC 3.1.1.3.) (Choi et al., 2018). This enzyme not only
catalyses the hydrolysis process but as well the esterification process, as well as the creation
of the link between alcohol carboxyl and hydroxyl groups of the carbolic groups. This
property makes them have a wider application in the biotechnological field. The superiority
which they have over other catalysts is that they are readily available, and in terms of
handling, they require no complexity (Li et al., 2010). Additionally, they do not necessitate
for coenzymes, with a high level of tolerance to organic solvents and are as well stable. The
diagram below indicates the yield obtained by different researchers. The optimum conditions
for the hydrolysis process, according to the enzyme utilised is the temperature of 25.53
degrees Celsius, and ph. of 6.86 (Wang and Tao, 2016).

Literature review 3
Deoxygenation
Peng et al conducted numerous investigations on the deoxygenation of fatty acids for the
production of biofuel. The researchers utilised different catalyst, at a constant temperature of
300-degree Celcius. These catalysts include Ni, Rh, Pt, Ir, and Ru. Ni-Raney, PdPt/C, and
Os/C; and 1, 5, and 10% by weight Pd/C. Pd/C as a catalyst was found to be the most active
through the deoxygenation of stearic acid (Peng et al., 2012). On the other hand, Choi and
colleagues conduct an investigation to determine the possibilities of obtaining alkanes
without hydrogen addition. They utilised a catalyst based on W/Pt/TiO2 , which yielded 86%
of the catalytic deoxygenation reaction.
In terms of the mode in which the deoxygenation experiment is conducted, both the batch and
continuous modes can be applied. A continuous reactor system having unreacted acid cycle
can be used to improve the yield of the expected alkene through minimizing the time and
exposure of the alkene within the high-temperature reactor. In this way, the small
hydrocarbons and carbon dioxide can be recovered. The continuous mode proves to bet the
best for the deoxygenation process, as it can be optimised to regulate the reactions
temperatures as well as maximizing the product composition and yield (Li et al., 2015).
In similar research, the author acknowledges the high requirement for hydrogen on the
deoxygenation process and thus offers a suggestion to an experiment with least use of
hydrogen consumption-selective deoxygenation (Hollak et al., 2014). The authors note that
the most active catalyst for the process is the bi-functional catalysts which comprise of a
combination of active metal phase as well as oxophilicity. One significant advantage is that
with limited use of hydrogen in the process, the stability of the process and the entire process
activity is improved. Hence, a recommendation in the utilisation of internally available
hydrogen in the biofuel.