Abstract
This study characterized the generation and transformation of tars, chars, and gases during the co-pyrolysis-to- co-gasification continuum of Pennisetum hydridum (PHY) and waste tires (WT) as a product of temperature, atmosphere, and synergy. Light tar components (ketones, furans, phenols, and acids) present in primary low- temperature pyrolytic oil underwent deoxygenation and ring-opening, transforming into hydrocarbons. These hydrocarbons were subsequently converted to thermally stable polycyclic aromatic hydrocarbons (PAHs) in high-temperature tar via reforming reactions. WT enhanced the deoxygenation of oxygen-containing compounds derived from PHY and supplied a carbon chain framework, promoting PAHs formation. CO_2 primarily facilitated the thermal cracking of phenols, furans, and ketones into PAHs precursors, thus favoring aromatization. However, at 750 ℃, CO_2 shifted carbon allocation in organic products toward CO, suppressing PAHs formation. For char products, elevated temperatures and CO_2 gasification significantly enhanced the application potential for porous carbon by increasing specific surface area, pore volume, and porosity. At 950 ℃, specific surface area of char increased by 504.08 % in N_2/CO_2 and 643.99 % in pure CO_2 compared to reference conditions. The addition of highly volatile PHY promoted S transfer from the char phase to the gas and oil phases. S retained in the char formed stable aromatic S compounds through cyclization reactions, with its preferential distribution within high- temperature char. These results provide valuable insights for controlling high-temperature tar formation, utilizing char resources, and managing S-containing pollutants during co-pyrolysis-to-co-gasification continuum.
NETL
NSTL
Elsevier