Hydrotreating reaction of vegetable oil is an alternative method for the production of
renewable biodiesel fuel. This reaction involves conversion of triglycerides into
normal alkanes, leads to a deoxygenated and stable product, which is fully compatible
with petroleum derived diesel fuel. The hydrotreating process uses hydrogen to
remove oxygen from triglyceride molecules at elevated temperature in the presence of
a solid catalyst.
This work focused on the development of microtechnology-based chemical reaction
process for liquid biofuel production from oil-based biofuel feedstock. A hydrotreating
reaction of oleic acid and triolein as model compounds and jatropha oil as real
feedstock was studied in a continuous flow microchannel reactor of inner diameter
500 μm and of varied length; 1.5 - 5 m. The microchannel reactor was fabricated from
SS-316. The walls of the microreactor were coated with a thin Al₂O₃ film, which was
then impregnated with Ni-Mo catalyst containing phosphorus as promoter. The
reactions were carried out in the temperature range of 275-325 °C, residence time in
the range of 11-40 s and at constant system pressure of 500 psig.
The results showed that the microchannel reactor was suitable for the hydrotreating
process. Complete conversion of the fatty acid hydrotreating reaction was achieved at
a reaction temperature of 325 °C. Hydrotreating of fatty acids occurred primarily via
hydrodeoxygenation and the main liquid products were octadecane and
heptadecane. Fatty alcohol, fatty acid and long chain esters were formed as reaction
intermediates. Hydrotreating of triglycerides proceeded via the hydrocracking of
triglycerides into diglycerides, monoglycerides and fatty acids. Then fatty acids were
subsequently deoxygenated to hydrocarbons. The conversion of fatty acids and
triglycerides increased with increasing temperatures.
A detailed mathematical model was developed to represent this two-phase chemical
reaction process. The mathematical model was entirely based on first principles, i.e.
no adjustable or correlation parameters were used. Kinetic parameter estimation was
performed and the predicted results were in good agreement with experimental