Release and generation of polycyclic aromatic hydrocarbons during co-pyrolysis of straw and coal: A case of corn straw and brown coal

Abstract

The release of polycyclic aromatic hydrocarbons (PAHs) during the pyrolysis of corn straw, brown coal, and their mixtures was investigated in this study. The mixing ratios were the essential factor in determining the release and generation of PAHs. Adjustments to the mixing ratio revealed that the activation energy reached its nadir at a corn straw proportion of 75%. As the corn straw proportion increased, PAHs’ yield and toxic equivalents decreased. Furthermore, this study elucidated the generation of PAHs in the products by integrating experiments and reaction kinetics calculations. Low-ring and medium-ring PAHs were generated more readily, while the content of high-ring PAHs and product toxicity decreased rapidly upon adding corn straw. Finally, the high oxygen content in corn straw generates oxygen radicals that reduce the concentration of hydrocarbons and benzenes, which mitigates the generation of PAHs and enhances the quality of the resultant oil.