Effect of CO2-rich atmosphere on nitrogen configuration of char and bio-oil during nitrogen-rich pyrolysis of cellulose

Abstract

Different volume ratios of carbon dioxide and nitrogen were mixed into the nitrogen-rich pyrolysis of cellulose, resulting in the production of nitrogen-doped biochar and nitrogen-containing bio-oil. When the urea mixture ratio was greater than 50%, the added CO2 promoted the production of nitrogen-containing bio-oil, reaching a maximum of 26.03% (M = 50%) at 10 vol% CO2 + 90 vol% N2. Pyridine, pyrrole, and amines were the main nitrogen-containing compounds produced when using atmospheres of pure nitrogen and carbon dioxide. Upon increasing the volume ratio of CO2, the nitrile content increased significantly, becoming one of the main nitrogen-containing compounds. In addition, due to chemical stability, the thermal conversion of CO2 demands a significant input of energy, so the required activation energy also increased. Adding CO2 to simulate high-temperature anoxic flue gas is a promising method for biomass pyrolysis to obtain nitrogen containing chemicals with high added value and high nitrogen doped Biochar.