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This study proposed an innovative method, that biomass catalytic pyrolysis for 4-vinyl phenol under NH 3 atmosphere with nitrogen-doped biochar catalyst, which could realize the in-situ regeneration of the catalyst. Results indicated that NH 3 and nitrogen-doped biochar catalyst could significantly increase the bio-oil yield (up to 68 wt%) and the phenols content (80%). The selectivity and absolute yield of 4-vinyl phenol were 28% and 5.85 wt%, respectively. N/O-containing groups in the catalyst and free radicals from NH 3 promoted the break of ester bonds and β-O-4 bonds, and converted phenols intermediates to 4-vinyl phenol. Meanwhile, NH 3 also acted as activator and nitrogen dopant, which realized the in-situ regeneration of the catalyst. The regeneration rate of nitrogen content and S BET of the catalyst was up to 84.5%-150% and 72.9%-85.4%, respectively. In addition, the nitrogen-doped biochar catalyst also showed good stability and reusability, and the yield of 4-vinyl phenol was still as high as5.85–6.05 wt% after repeated use of BC10 catalyst for 3 times. [Display omitted] • Catalytic pyrolysis for phenols with in-situ regeneration of catalyst was studied. • The content of phenols reached 80% with 5.85 wt% valuable 4-vinyl phenol. • NH 3 regenerated N-doped biochar catalyst in situ as activator and nitrogen dopant. • Amount of N-doped biochar increased rather than reduced after catalytic pyrolysis. • Formation pathways of 4-vinyl phenol under NH 3 with N-doped biochar was proposed. [ABSTRACT FROM AUTHOR]

[Display omitted] • Efficient co-valorization of waste cooking oil into biofuel and carbon nanotubes. • Natural biochar shows excellent deoxygenation performance and good stability. • Correlation between AAEM in biochar and selectivity of A&E and HCs in bio-oil. • Potential for obtained biofuel to serve as a precursor for jet fuel. • Feasibility and profitability of integrated production process demonstrated. Valorizing renewable precursors into high-quality biofuel and functional carbon nanomaterials can considerably improve the economic viability. Here, we propose a process for integrated production of high-quality biofuel and carbon nanotubes from waste cooking oil via catalytic pyrolysis coupling with chemical vapor deposition (CVD) technology. The natural biochar catalyst demonstrates excellent deoxygenation performance and good stability in catalytic pyrolysis process. The alkali/alkaline earth metal species (AAEMs) content in biochar catalysts has a strong correlation with the selectivity of esters and hydrocarbons in bio-oil. The biofuel obtained under optimal conditions exhibited potential as a precursor for jet fuel. The CVD process convert pyrolysis gas into carbon nanotubes with yield of 2.13%. The technical–economic analysis demonstrated the feasibility of the integrated process, projecting profitability and substantial total profit over a ten-year period. Overall, this study improves the economic viability of the waste cooking oil pyrolysis process and supports its wider commercial application. [ABSTRACT FROM AUTHOR]

Realizing the recovery and valorization of waste polyethylene terephthalate (PET) plastics into value-added products have gained significant importance. This study successfully synthesized aromatic nitriles, specifically terephthalonitrile (TPN), from waste polyethylene terephthalate (PET) plastic through in situ catalytic pyrolysis with urea and γ-Al 2 O 3 catalyst. Based on distributed activation energy model, positive interaction between waste PET and urea is responsible for improved thermal decomposition kinetics. The dosage of urea and pyrolysis temperature significantly influenced TPN production. TPN yield reached 32.5% with ca. selectivity of 85% at 550 °C and equivalent urea dosage. Density functional theory calculations validated the role of active ammonia in reducing energy barriers and thus facilitating PET depolymerization. The study highlights the feasibility of recycling waste PET into valuable aromatic nitriles through in situ catalytic pyrolysis with urea and enhances the understanding of the pyrolysis process. [Display omitted] • Feasibility of recycling waste PET into valuable aromatic nitriles highlighted. • Enhanced thermal decomposition kinetics through positive PET-urea interaction. • 32.5% of terephthalonitrile with 85% selectivity was achieved at optimal conditions. • Influence of urea dosage and pyrolysis temperature on TPN production. • Density functional theory calculations validate role of NH 3 in PET depolymerization. [ABSTRACT FROM AUTHOR]