Development of metal-doping mesoporous biochar catalyst for co-valorizing biomass and plastic waste into valuable hydrocarbons, syngas, and carbons

The present study was aimed to explore a cost-effective route to produce metal-doping mesoporous graphite-like catalysts, which utilized metal chlorides (ZnCl₂, FeCl₃, and NiCl₂) to modulate biochar within mesopore-creating, metal-doping, and graphitization simultaneously accomplished in the one-step thermal process. The properties of these as-synthesized catalysts were comprehensively characterized by a sequence of analytic methods (e.g., BET, NH₃-TPD, SEM, EDS, TEM, FTIR, XRD, and Raman analysis). The carbon yields and HHV of bio-oils from ex-situ catalytic fast co-pyrolysis of biomass and plastic waste over the as-synthesized catalysts were around 50C% and 43 MJ/kg, respectively. Up to 96% of selectivity toward hydrocarbons when Ni/C was used as the catalyst, of which aromatic hydrocarbons accounted for nearly 40%. On the other hand, Fe/C was in favor of the production of H₂ (90 NmL/g_feedstock) and syngas (~133 NmL/g_feedstock), which respectively occupying ~44 vol% and over 64 vol% in the gas; it also favored the generation of carbon nanotubes. Biochar produced from co-pyrolysis showed a high HHV at 28.33 MJ/kg, indicating the high potential as a solid fuel. In addition, the thermal decomposition behaviors and kinetics of biomass and plastic waste over the as-synthesized catalysts were also investigated by thermogravimetric analysis.