Dynamic adsorption and DFT simulation of Cl-VOCs on transition metal-doped microporous zeolite-templated carbon: Adsorption mechanism and regeneration evaluation

Dichloromethane (DCM), a widely used industrial solvent, represents a primary anthropogenic source of chlorine-containing volatile organic compounds (Cl-VOCs). The adsorption of DCM is usually impeded by the irregular pore structure of commercial activated carbon. To address this limitation, this study developed Fe 3+ modified zeolite-templated carbons (ZTC) for DCM removal at ambient temperature. Comprehensive characterization through BET, XRD, Raman, SEM, TG/DTG, XPS, and NH 3 -TPD confirmed the uniform distribution of Fe 3+ within the ZTC pore channels and revealed its significant impact on surface functional groups and acid sites. The optimized 3 % Fe@ZTC adsorbent demonstrated markedly enhanced performance, achieving a DCM adsorption capacity of 227.9 mg·g −1 at 25 °C. Furthermore, it exhibited excellent regenerability, maintaining 70.2 % of its initial capacity after three regeneration cycles at 500 °C. Density Functional Theory (DFT) calculations provided mechanistic insights, showing that Fe 3+ modification substantially increased the adsorption energy from 0.90 eV on raw ZTC to 3.56 eV on Fe@ZTC. This enhancement was attributed to uniform Fe 3+ doping, which created hard acid sites that strongly interacted with the hard base site (Cl) of DCM molecules, facilitating Fe-Cl bond formation and substantial charge transfer. This work presents a viable strategy for developing efficient adsorbents for DCM removal from industrial waste gases.