Synergistic Degradation of Toluene/Styrene Binary VOCs by a Monolithic α-MnO₂/Cordierite Heterogeneous Catalyst Coupled With Non-Thermal Plasma: Mechanisms and By-Products Suppression.

The practical application of non-thermal plasma-catalysis hybrid systems for industrial off-gas treatment faces significant challenges due to unavoidable generation of deleterious by-products. In this study, a novel post-plasma catalytic system was developed, incorporating an α-MnO2/Cordierite honeycomb monolithic heterogeneous catalyst designed for the simultaneous removal of toluene and styrene. Experimental results revealed that the plasma-catalyst system achieved almost 100% degradation efficiency and exhibited a COx selectivity of 51.8%, thereby effectively reducing the formation of by-products. Notably, during co-processing, the removal efficiency of toluene was diminished, whereas the conversion of styrene remained stable under comparable conditions. The integration of the catalyst imparted strong resilience to variations in pollutant concentration and gas flow rates, demonstrating significant adaptability for industrial-scale emission control. The synergistic and inhibitory interactions governing the co-degradation of binary volatile organic compounds (VOCs), along with the pathways of by-product formation, were elucidated through real-time mass spectrometric analysis of transient intermediates. This work represents a pioneering advancement in the integration of monolithic catalysts with plasma technology, offering fundamental mechanistic insights into the co-elimination of multicomponent VOCs and facilitating the accelerated industrial implementation for the treatment of complex waste gas streams.