Mechanistic insights into de novo synthesis for chlorobenzene formation under simulated MSWI conditions.

Chlorinated volatile organic compounds (CVOCs), particularly chlorobenzenes (CBzs), are hazardous pollutants formed during municipal solid waste incineration (MSWI). This study investigated the catalytic roles of copper and iron chlorides/oxides in the de novo synthesis of CBzs under simulated MSWI conditions. CuCl2 exhibited the highest catalytic activity, primarily driven by its dynamic redox behavior and phase transformations. TG-DSC, XRD, and XPS analyses revealed oxidation-reduction cycles between 280 and 290 °C, producing intermediates such as Cu2OCl2 that facilitated catalytic chlorination and electrophilic substitution. GC-MS identified trichlorobenzene and tetrachlorobenzene as predominant products in N2, whereas higher oxygen levels promoted deeper chlorination but suppressed highly chlorinated congeners due to competitive oxidation. Complementary thermodynamic calculations (ΔG°) confirmed the temperature-dependent feasibility of stepwise chlorination, consistent with the suppression of highly chlorinated CBzs under oxygen-rich conditions. These findings highlight the distinct catalytic roles of Cu and Fe, reveal CuCl2's dual function in redox cycling and chlorination, and provide mechanistic insights and practical strategies to mitigate CVOC emissions and improve MSWI sustainability.