Evaluation of antioxidants on the thermo-oxidative stability of soybean biodiesel

Journal of Thermal Analysis and Calorimetry (Impact Factor: 2.21). 07/2012; 112(2). DOI: 10.1007/s10973-012-2650-6

ABSTRACT This work shows the evaluation of three anti-oxidants (2,6-di-t-butyl-4-methylphenol (BHT)—synthetic antioxidant, hydrogenated cardanol (HC), and alkyl hydrogenated cardanol (AHC)—both derived from cashew nut shell liquid) on the thermo-oxidative stability of the soybean biodiesel. The antioxidants were added at con-centrations of 200, 300, and 400 ppm, and the oxidative stability of the biofuel with and without antioxidants were investigated by thermogravimetric analysis (TG-DTG and IPDT) and Metrohm 743 Rancimat per the EN 14112 method. The results showed that all antioxidants contrib-uted for the thermo-oxidative stability of the soybean biodiesel as follows: soybean biodiesel \ soybean biodie-sel ? BHT \ soybean biodiesel ? HC \ soybean biodie-sel ? AHC. In the Rancimat method, the results showed that the antioxidants influenced the biodiesel stability with an increase of at least 71 %.

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    ABSTRACT: An oil-soluble additive alkylated diphenylamine (ADPA) was synthesized. The antioxidant activities of ADPA and dilauryl thiodipropionate (DLTDP) as well as their mixtures in PAO10 were evaluated by rotary bomb oxidation test, pressurized differential scanning calorimetry, hot oil oxidation test, and thermogravimetry. All the tests showed that the anti-oxidation stability of ADPA was significantly improved with the addition of DLTDP. The kinetic parameters of thermal-oxidative process were also evaluated using the Kissinger method which has been widely used for the determination of activation energy and pre-exponential factor. The results indicated that ADPA could significantly improve the activation energy of PAO10 and reduce the rate of the thermal-oxidative reaction when combining with DLTDP antioxidant. All these results demonstrated that the combination of ADPA and DLTDP revealed a good synergistic effect and could effectively enhance the thermal-oxidation stability of PAO10. The proposed mechanism of the inhibition involved a synergy between ADPA and DLTDP.
    Journal of Thermal Analysis and Calorimetry 08/2014; 117(2):925-933. DOI:10.1007/s10973-014-3808-1