Iron-catalyzed pyrolysis assisted by plastics: A route to highly graphitized porous biochar

The development of highly graphitized porous biochar is an important strategy for biomass utilization. In this study, an iron-catalyzed pyrolysis method assisted by plastics was proposed for the fabrication of highly graphitized porous biochar. Three types of plastics, polyethylene (PE), polypropylene (PP), and polystyrene (PS), were introduced into the iron-catalyzed graphitization process using two approaches (mixing the plastics with bamboo or introducing plastic-derived volatiles to preformed bamboo char). The addition of PS-derived volatiles resulted in the biochar sample exhibiting the lowest I D /I G ratio (1.31) and the high specific surface area (822.66 m 2 /g) among all the samples. The results demonstrated that FeCl 3 and PS-derived volatiles facilitated the formation of highly graphitized porous biochar. Finally, the mechanism of PS-assisted iron-catalyzed biomass graphitization was proposed. Ferric chloride (FeCl 3 ) acted as an activator to enhance graphitization and promoted pore formation in the biochar. The aromatic hydrocarbons from PS-derived volatiles induced the growth of graphitic structure on the surface of Fe-based species, thereby increasing the degree of graphitization. This study provides a theoretical basis for the development of highly graphitized biochar.