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This study aims to clarify the thermal decomposition mechanisms of toluene adsorbed on activated carbon functionalized with carboxyl(—COOH) or amino(—NH2) groups through reactive molecular dynamics simulations. Functionalized activated carbon fragments were constructed in Materials Studio, geometrically optimized using the conjugate gradient method, and annealed under an NVE ensemble to relieve local stress. Amorphous cells with a density of 0.6 g/cm3 were generated to replicate porous structures, and toluene was subsequently packed into the activated carbon to achieve a final density of 0.8 g/cm3 using the COMPASS Ⅲ force field. The simulations were conducted in LAMMPS under periodic boundary conditions within a temperature range of 2 000-3 000 K. Each system was first equilibrated at 300 K under the NVT ensemble for 10 ps, followed by 200 ps of high-temperature decomposition at each specified temperature, using a time step of 0.2 fs. Structural characterization—including density, radial distribution function, surface area, pore volume, and porosity—demonstrated good agreement with available experimental data. The results revealed distinct decomposition behaviors between the two functionalized systems. In the —COOH system, initial exothermic decarboxylation is followed by endothermic reactions, resulting in a rapid increase in enthalpy and a heightened risk of thermal runaway. Conversely, the —NH2 system maintains relatively stable enthalpy through deamination and hydrogen transfer, leading to milder decomposition. Radical analysis indicates that O· radicals generated by carboxyl decarboxylation in the —COOH system preferentially participate in oxidative consumption reactions, thereby suppressing the reverse recombination of decomposition fragments. In contrast, the —NH2 system exhibits high concentrations of H· radicals, inducing a “hydrogen pool effect” that triggers reverse reactions and fluctuations in decomposition behavior. Product distribution further distinguishes the two systems: the —COOH system primarily produces H_2O, CO2, CO, and char, with suppressed tar formation. In contrast, the —NH2 system generates substantial amounts of H2, NH3, and HCN at low temperatures, while also promoting char decomposition at higher temperatures. Intermediate analysis reveals that C—H—O species dominate in the —COOH system, stabilizing the reaction pathways. In the —NH2 system, however, C—H—N intermediates accumulate, which enhances the formation of toxic gas precursors. These contrasting radical-mediated mechanisms, influenced by surface functional groups, govern decomposition kinetics, product variation, and thermal stability. The findings underscore the significant role of functionalized activated carbon in regulating Volatile Organic Compound(VOC) decomposition pathways. Furthermore, this research provides theoretical guidance for the design of efficient, low-risk materials for VOC treatment and for the safe management of thermal decomposition processes.
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Basic Information:
DOI：10.13637/j.issn.1009-6094.2025.1536
China Classification Code:TQ424.1;X701
Citation Information:
[1]Zhao Jiangping,Liang Zhenghao.Mechanistic effects of carboxyl and amino groups on toluene pyrolysis over activated carbon[J].Journal of Safety and Environment,2026,26(08):2996-3008.DOI:10.13637/j.issn.1009-6094.2025.1536.
2026-02-03
2026-02-03
2026-02-03