Preparation of low-nitrogen bio-oil from co-pyrolysis of waste tobacco stem and corn stalk: Product characteristics and denitrogenation mechanism

Substances such as nicotine and tobacco proteins in waste tobacco stem (TS) could result in higher content of nitrogenous compounds and lower calorific value and cleanness in the pyrolysis bio-oil. This study focused on the co-pyrolysis of TS with corn stalk (CS) to investigate the product characteristics and denitrogenation effects during the co-pyrolysis process. The results indicated that co-pyrolysis of TS with CS remarkably reduced nitrogenous compounds from 43.75% to 6.42% in bio-oil, at a 1:1 blending ratio of TS and CS. With the addition of CS, the most of nitrogen-containing and oxygen-containing compounds were removed from bio-oil. Co-pyrolysis of TS with three main components in biomass was also conducted. It revealed that the lignin component in the CS played a key role in bio-oil denitrogenation during co-pyrolysis. When the blending ratio of TS and lignin was 1:1, 39.45% of nitrogenous compounds in the bio-oil was reduced. Lignin promoted the amino migrates from bio-oil to gas and char.