Electrically heated tobacco product (eHTPs) waste pyrolysis for clean syngas production over Ni/CaO DFM catalyst

The resource recovery potential of electronic cigarette waste was explored through pressurized pyrolysis, focusing on syngas, oil, and biochar production along with kinetic analysis. Pyrolysis experiments in a laboratory-scale autoclave reactor revealed syngas compositions of CH₄ (24.3–27.0 %), H₂ (8.1–11.5 %), CO (3.3 %), and CO₂ (21.5–59.7 %). The addition of Ni and CaO increased the syngas lower heating value from 12.9 to 22.4 MJ/Nm³, corresponding to an improvement of approximately 74 %, while reducing CO₂ by 36.5 % and increasing CH₄ by 18.7 %. Oil contained a high aromatic content (55.8 %), with major compounds including phenol (25.6 %) and naphthalene (18.5 %), while biochar exhibited a carbon retention rate of 47.0 wt% with excellent thermal stability. Kinetic analysis using Friedman, KAS, and FWO methods determined activation energy ranges of 192–437 kJ/mol. Master plot analysis indicated that pyrolysis reactions followed diffusion and nucleation models. The results highlight distinct kinetic behaviors based on material composition. These findings demonstrate the feasibility of converting electronic cigarette waste into high-value products while enhancing syngas quality and improving reaction efficiency. Optimized pyrolysis conditions contribute to sustainable waste management and the advancement of pyrolysis technologies, supporting the development of efficient resource recovery processes.