Atmospheric distillation with biochar-catalyzed bio-oil polymerization into co-polymerized bio-coal

Efficient utilization of biomass-derived bio-oil and improvement of the properties of its atmospheric distillation product “bio-coal” are of significant importance. This study investigated the effect of biochar on bio-coal yield and its role in enhancing the combustion performance of bio-coal. Fast pyrolysis of wheat straw was employed to produce bio-oil and biochar, with the latter subsequently added to the bio-oil during atmospheric distillation to yield co-polymerized bio-coal. The results show that the addition of 2 % biochar increases the bio-coal yield by 9.84 wt%. Bio-coal produced with 3 % acid pickling biochar exhibits a high fixed carbon content (77.32 wt%), low sulfur content (0.12 wt%), an advanced degree of coalification, and a high heating value (30.48 MJ/kg). Moreover, the combustion performance of the co-polymerized bio-coal was significantly improved, as evidenced by a lower ignition temperature (T i ), better ignition characteristics (D i ), a higher combustion characteristic index (CCI), and a maintained high flame stability index (F i ). In summary, this study presents biochar as a green catalyst to promote the polymerization of bio-oil into bio-coal. The resulting co-polymerized bio-coal shows promise as a sustainable alternative to conventional coal, thereby facilitating efficient valorization of both bio-oil and biochar.