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

Abstract

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/Al2O3 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.