Hydrocarbon production from coconut oil by hydrolysis coupled with hydrogenation and subsequent decarboxylation

- Hydrocarbon production from coconut oil was studied.
- The process consists of hydrolysis/hydrogenation and subsequent decarboxylation.
- The comparison between coconut and rapeseed oils with this process was discussed.
- The product meets the Japanese diesel standard by blending with fossil diesel.

Hydrocarbon production from coconut oil for use as a renewable diesel was studied by a two-step process: hydrolysis coupled with hydrogenation and subsequent decarboxylation. In the first step, coconut oil was treated in subcritical water at 270 °C/5 MPa (H2) with a Pd/C catalyst for 60 min, in which triglycerides were hydrolyzed and hydrogenated into saturated fatty acids with a yield of 91.2 mol%. In the second step, the obtained saturated fatty acids were decarboxylated into hydrocarbons as renewable diesel at 300 °C/1 MPa (H2) with Pd/C for 360 min. However, its yield was only 53.3 mol% based on coconut oil. Although the reaction time for the hydrolysis/hydrogenation of coconut oil was the same as that of rapeseed oil that was studied in previous work, the complete decarboxylation conversion took three times longer. Such differences in reaction time and final hydrocarbon yield are related to the shorter coconut oil chains. The obtained renewable diesel was evaluated and their cold-flow properties were satisfactory, but the flash point and kinematic viscosity were out of the fossil diesel specification standard range, unlike those from rapeseed oil. The renewable diesel properties could be improved by blending an adequate amount of fossil diesel to satisfy the specification.