(2025) Energy Conversion and Management_Production of carbon-negative syngas through CO₂-driven thermochemical conversion of acacia sawdust

Choi D.; Cho H.; Lim J.; Kwon E.E.

(1968904) Energy Conversion and Management ISSN:  Vol.329 Issue. Article No.119659 DOI: 10.1016/j.enconman.2025.119659

This paper proposes a strategic approach for producing carbon-negative syngas through the thermochemical conversion of biomass using acacia sawdust as a model compound. CO₂ was employed as the reactive medium during the pyrolysis of acacia sawdust to increase the conversion of carbon in biocrude into syngas. In the single-stage pyrolysis, more production of CO under CO₂ than N₂ condition was observed above 580 ˚C. This observation demonstrated that the reaction in gaseous medium between the CO₂ and volatile matter released from the thermolysis of acacia sawdust did occur. However, the kinetics of the reaction in gaseous medium driven by CO₂ were slow. As such, a Ni-based catalyst was introduced to promote the kinetics of reaction in gaseous medium driven by CO₂. Introducing CO₂ in the catalytic pyrolysis further increased the yield of syngas, reaching 22.8 mmol gsample-1, which was higher than that under N₂ conditions (18.6 mmol gsample-1). The proposed process (CO₂-driven catalytic pyrolysis of acacia sawdust) achieved a net CO₂ emission of −151.0 mg gsample-1. All the experimental findings show that the CO₂-drvien catalytic pyrolysis system may serve as an effective strategy for carbon-negative syngas production, contributing to greenhouse gas (CO₂) mitigation. © 2025 Elsevier Ltd

This study was supported by the National Research Foundation of Korea (NRF) grant funded by the Korean Government (MSIT) (No. RS- 2023-00219667), the SKLMP Seed Collaborative Research Fund (No. SKLMP/SCRF/0053), and the Dean’s Research Fund (No. RG12/2024- 2025R/ICRS-7/ICRS-8) at The Education University of Hong Kong. Dohee Kwon acknowledges the financial support from the Hyundai Motor Chung Mong-Koo Foundation. Elsevier Ltd