Enhancement of syngas through integrating carbon dioxide in the catalytic pyrolysis of plantation waste

This study introduces the sustainable recovery of energy from plantation waste by converting rubber tree residue (RTR) into syngas through carbon dioxide (CO₂)-assisted pyrolysis. The investigation centers on elucidating the specific impact of CO₂ on the pyrolysis of rubber tree residue, emphasizing its significant influence on enhancing syngas production. At temperatures ≥ 500 °C, CO₂ engages with volatile matters (VMs) released during the thermolysis of rubber tree residue, increasing carbon monoxide (CO) yields. To further optimize the process, catalytic pyrolysis setups incorporating additional heat (600 °C) and a nickel-based catalyst (Ni/Al₂O₃) were implemented. These experimental configurations substantially increased syngas production from 19.51 to 24.24 mmol g⁻¹, particularly amplifying CO yields under CO₂ conditions 2.58-fold compared to nitrogen (N₂) conditions. This enhancement is attributed to the partial oxidation of volatile matters facilitated by CO₂. Additionally, the Ni/Al₂O_₃ catalyst played a pivotal role in expediting the gas-phase homogeneous reaction of CO₂ with volatile matters, leading to further improved syngas production. Indeed, the syngas yield in the catalytic pyrolysis in the presence of CO₂ was 24.24 mmol g⁻¹, which increased by 1.24 times in reference to the result under the N₂ environment. The identified functional role of CO₂ presents an opportunity to enhance the sustainability of waste management by optimizing carbon utilization and generating value-added products. Copyright © 2024 Elsevier Ltd.