Enhancement of C₈–C₁₆ hydrocarbons distribution in bio-oil from the catalytic pyrolysis of animal manures using physically or chemically activated biochar catalysts

This study investigates the potential of animal manure to produce C₈-C₁₆ hydrocarbons. To this end, catalytic pyrolysis of cow manure (COM), chicken manure (CHM), and swine manure (SWM) was conducted using a biochar catalyst. Based on GC/MS semi-quantitative estimates, catalytic pyrolysis of SWM showed a higher relative proportion of C₈-C₁₆ hydrocarbons than CHM and COM, attributed to its lower nitrogen content. The use of ZnCl₂-treated biochar (AC-Z) resulted in 1.41-, 1.24-, 1.18-, and 1.21-fold increases in the relative proportion of C₈–C₁₆ hydrocarbons in the bio-oil compared with those obtained using raw biochar, HZSM-5, CO₂-activated biochar, and KOH-activated biochar, respectively. This performance aligns with its physicochemical properties, which facilitate the conversion of alkenes into aromatic hydrocarbons. Furthermore, AC-Z demonstrated satisfactory stability, retaining 35.0% selectivity after three consecutive cycles of spent catalyst reuse. Overall, this research provides a new approach for managing abundant livestock manure.