(2026) Energy_Carbon-negative conversion of oil palm waste into syngas through CO₂-assisted catalytic pyrolysis

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

(Elsevier Ltd) Energy ISSN: 3605442 Vol.364 Issue. Article No.142427 DOI: 10.1016/j.energy.2026.142427

Oil palm is one of the most widely cultivated oil crops, generating substantial lignocellulosic wastes (residues) during cultivation and processing. Although these wastes represent promising carbon neutral resources for energy production, their structural complexity hinders efficient conversion through conventional biological processes. Thus, this study employed a thermo-chemical route to convert oil palm shell (OPS) into syngas. Carbon dioxide (CO₂) introduced into OPS pyrolysis to promote syngas production. CO₂ underwent in reactions with OPS-derived volatile compounds (VCs), acting as a partial oxidant that promoted their conversion into syngas, particularly CO. However, CO production enhancement was mainly observed above 580 °C, indicating that CO₂-induced reactions were kinetically limited at lower temperatures. To promote CO₂ reactivity, pyrolysis of OPS using a Ni-based catalyst was performed at pyrolysis temperatures at 500, 600, and 700 °C and CO₂ concentrations from 0 vol% to 80 vol%. Under optimized conditions, CO₂-mediated catalytic pyrolysis produced 188.1 mmol of CO-rich syngas, substantially higher than the 16.8 mmol obtained from conventional OPS pyrolysis. In addition, the observed oxidative mechanistic role of CO₂ contributed to reducing coke formation on the catalyst by achieving the conversion of VCs into CO. Compared with catalytic pyrolysis of OPS under inert (N₂) reaction environment, the proposed approach reduced net CO₂ emissions to −351.8 mg gOPS^−1, while increasing the recoverable energy from the resulting syngas by 45.1%, from 7.1 kJ gOPS⁻¹ to 10.3 kJ gOPS⁻¹. Conclusively, the proposed pyrolysis platform enabled carbon-negative syngas production while improving energy recovery. © 2026 Elsevier Ltd. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

This work was supported by the Commercialization Promotion Agency for R&D Outcomes ( COMPA ) grant funded by the Ministry of Science and ICT ( MSIT , Korea) (Grant No. RS-2023-00304763 ) and by the Ministry of Small and Medium-sized Enterprises (SMEs) and Startups ( MSS ), Korea, under the \u201CDevelopment of COF wet etching system to implement ultra-fine circuit patterns with space less than 10\u339B\u201D, (Grant No. S3453150 , SE-26-0010 ).