Thermally induced non-catalytic in-situ transesterification of lipids in rubber seed (Hevea brasiliensis) for sustainable biodiesel production

초록

Conventional biodiesel production relies largely on edible oil feedstocks and oil extraction, limiting its scalability and sustainability. Therefore, a thermally induced non-catalytic transesterification strategy is presented to directly convert inedible biomass into biodiesel without prior oil extraction. Rubber seed ( Hevea brasiliensis ), an abundant waste from rubber plantations with a high lipid content (> 30 wt%), was chosen as a feedstock for a case study. To improve process sustainability, dimethyl carbonate (DMC) was employed as a green acyl acceptor. Catalytic and non-catalytic process of rubber seed oil with methanol was conducted as a reference. The maximum biodiesel yield from catalytic conversion reached 62.0 wt% within 60 min at 63 °C, whereas non-catalytic method yielded 90.3 wt% at 360 °C within 1 min, indicating enhanced reaction efficiency. Under same non-catalytic conditions, using DMC reached a higher biodiesel yield of 94.8 wt%, presumably because of improved miscibility with rubber seed oil and enhanced mass transfer. Non-catalytic in-situ transesterification of rubber seed achieved a biodiesel yield of 27.8 wt% on a seed basis at 365 °C within 1 min, corresponding to 96.9 wt% on a lipid basis. The produced biodiesel was qualitatively and quantitatively analyzed by gas chromatography-mass spectrometry and gas chromatography-flame ionization detection, respectively, and its fuel properties were evaluated according to ASTM D6751 and EN 14214 standards. The energy potential of rubber seed-derived biodiesel from rubber plantations was calculated to be 7,450 MJ ha−1 year−1, which could reduce CO2 emissions by 5.0 million tons year−1 through diesel substitution across global rubber plantations.

키워드