(2026) Energy Conversion and Management_Thermally induced non-catalytic in-situ transesterification of lipids in rubber seed (Hevea brasiliensis) for sustainable biodiesel production

Lee S.; Kim M.; Song H.; Kwon E.E.

(Elsevier Ltd) Energy Conversion and Management ISSN: 1968904 Vol.365 Issue. Article No.121776 DOI: 10.1016/j.enconman.2026.121776

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. © 2026 Elsevier Ltd.

This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government Ministry of Science and ICT (MSIT) (Grant No. RS-2023-NR077231).