Microwave-Assisted Benzene Removal Using Zeolite-Mixed Metal Oxide Dual-Bed for Energy-Efficient Adsorption and Catalytic Oxidation

The efficient removal of trace volatile organic compounds (VOCs) from flue gas remains a critical challenge in environmental engineering. Microwave-assisted catalytic oxidation has emerged as a promising approach due to its ability to selectively and rapidly heat microwave-absorbing catalysts, thereby enhancing reaction kinetics and energy efficiency. In this study, we developed a dual-bed microwave-heated reactor system incorporating manganese oxide-modified Y-zeolite (MnOx/Y) and cobalt–copper-manganese mixed metal oxides (CoCuMnOx) for the abatement of trace benzene in air streams. System performance was evaluated under both dry and humid conditions. The pulsed microwave operation enabled efficient cyclic adsorption–desorption processes coupled with catalytic oxidation. Compared to the CoCuMnOx single-bed configurations, the MnOx/Y- CoCuMnOx dual-bed system exhibited significantly enhanced benzene removal efficiency. This improvement does not arise simply from increased catalyst amount, but from microwave-selective heating of the catalytic layer, which creates a spatial temperature gradient across the two beds. As a result, benzene is enriched in the MnOx/Y layer during adsorption and rapidly desorbed and oxidized in the microwave-heated CoCuMnOx layer during irradiation. Notably, the presence of humidity not only improved overall performance but also enabled optimization of catalyst distribution between the two beds. These results demonstrate that spatial separation of adsorbent and catalyst layers under microwave irradiation provides a practical strategy for coupling enrichment and oxidation processes, highlighting the potential of this approach for industrial VOC abatement.