(637e) Hydrotreating of Vegetable Oil In Microreactor

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.

In
this work, the catalytic hydrotreating of vegetable oil was studied in a
continuous flow microchannel reactor of inner diameter 508 [µm] and of varied length; 0.5 [m] ? 15 [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. Conversion
of vegetable oil was experimentally determined in the temperature range of
300-400 [°C], oil flow rate in the range of
0.1-0.3 [ml/min], with hydrogen-to-triglyceride molar flow ratio in the range
of 10-15, and at constant system pressure of 34 [bar]. The liquid products were analyzed in a gas chromatograph for
its composition of triglyceride, diglyceride, monoglyceride, fatty acid and
alkanes.

Detailed
mathematical model was developed to represent this two-phase chemical reaction
process.  Mathematical model is entirely based on first principles, i.e. no
adjustable or correlation parameters were used.  Figure 1 is schematic
representation of a section of the microchannel reactor used in numerical
simulation.

Both
experimental and numerical results show that microchannel reactor is well suited
for the hydrotreating process of vegetable oil. Hydrotreating of vegetable oil
in a microchannel reactor provides complete elimination of hydrogen mass
transport deficiency, which arises from low hydrogen miscibility in vegetable
oil.