In-situ bio-oil directional conversion mechanism of catalytic biomass pyrolysis over nitrogen-doped carbon preparation by grading of nitrogen-rich cow dung

N -doped carbon catalysts were prepared using corn straw (CS) and cow manure (CD) as carbon and N resources, and used for the CS catalytic fast pyrolysis in Py-GCMS to improve the quality of bio-oil products. Through the methods combining hydrothermal treatment and carbonization, the N from CD was efficiently fixed into the straw biochar, showing the better catalytic effect. The moderate carbonization temperature (600 C) and the lower HTC temperature benefited the improvement of N -doped biochars on the relative content of phenols in biooil, with the maximum increment of 8.32%. The pyridinic-N and pyrrolic-N in N -doped biochars mainly enhanced the relative content rather than the yields of phenols and ketones, respectively. Compared with the surface area and the degree of disorder, the types and content of N species in N -doped biochar had the greater promoting effect on the relative content of phenols in bio-oil.