Improvement of oxidation stability of fatty acid methyl esters derived from soybean oil via partial hydrogenation using dielectric barrier discharge plasma

Oxidation stability is an important biodiesel property. One of the methods to improve oxidation stability is partially hydrogenated fatty acid methyl esters (H-FAME). The present research studied the novel production technique of H-FAME derived from soybean FAME using non-thermal parallel-plate dielectric barrier discharge (DBD) plasma. This green hydrogenation method does not require a catalyst and can be performed under atmospheric pressure and at room temperature. The reaction using DBD plasma could effectively initiate the hydrogenation reaction, and the results showed similar performance to catalysis technique. The optimized process parameters for 35 mL of FAME were 25% H-2, 5.5 hours of reaction time, and ambient temperature. This condition exhibited the highest conversion of polyunsaturated FAMEs (C18:2 and C18:3) and the highest yield of C18:1. DBD plasma hydrogenation resulted in the reduction of iodine value from 128 to 67.4. The oxidation stability was enhanced from 2.13 to 10 hours while the cloud point increased from -1 degrees C to 11 degrees C (still within the ASTM D6751 standard). This plasma process is a new alternative and eco-friendly method for H-FAME production.