Enhanced Toluene Degradation Using Fe–Mn Bimetallic Catalyst in a Gaseous H2O2 Fenton-Like System

Fe-based Metal–Organic Frameworks (MOFs) show promise as heterogeneous Fenton-like catalysts; however, in the removal of hydrophobic VOCs, traditional wet Fenton systems suffer from slow Fe 3+ /Fe 2+ cycling and high gas–liquid mass transfer resistance, severely limiting their industrial application. To address these challenges, this study proposes a dual optimization strategy. Specifically, a gas-phase H 2 O 2 Fenton-like system was constructed to overcome mass transfer limits, and multivalent Mn was introduced into the MIL-100(Fe) to accelerate the Fe 2+ /Fe 3+ cycle. Among the synthesized catalysts, MIL-100(Fe 4 Mn 1 ) (4FM) exhibited superior catalytic performance, achieving 85% toluene degradation efficiency and a capacity of 87.17 μg C 7 H 8 /(g·min)) under optimized conditions, significantly outperforming its monometallic counterparts. Characterization results reveal that 4FM retains an ordered crystalline structure with highly dispersed active sites and an optimized pore architecture. Mechanistic studies indicate that Fe–Mn synergy induces an “electron pump” effect, utilizing the thermodynamic potential differences to accelerate the reduction of Fe 3+ to Fe 2+ . Concurrently, the system establishes dual reaction centers (Fe and Mn), where efficient Mn 2+ /Mn 3+ /Mn 4+ and Fe 2+ /Fe 3+ redox cycles facilitate sustained gaseous H 2 O 2 activation into hydroxyl radicals (·OH), promoting efficient toluene degradation. This study provides a promising strategy utilizing gas-phase Fenton-like catalytic technology to overcome kinetic and mass transfer bottlenecks in degrading of hydrophobic VOCs. Graphical