Coupling effect of pyrolysis temperature and condensing temperature on the enrichment of high value-added phenolic compounds in bio-oil from pyrolysis of crop straw

Pyrolysis experiments were performed using cotton straw and corn straw as raw materials at 723 and 773 K. The variations in condensation efficiency, moisture, and content of important components in bio-oil condensed from pyrolysis vapors were investigated in a water-bath condensation temperature of 313–363 K. The condensing efficiency, moisture, and content of important components of bio-oil increased with increased pyrolysis temperature. The single pyrolysis temperature provided limited control over the quality of bio-oil. The variation in condensing temperature affected the condensing of pyrolysis vapors. As the condensing temperature increased, the moisture in bio-oil was reduced by 200%, and the maximum content of the important components was elevated. The phenol content of the target bio-oil increased by 340.40%. For guaiacol and its derivatives, the relationship between condensing temperature and their content was analyzed using a polynomial fitting function to explore the phase-transition patterns.