Hybrid Plasma-Catalytic Oxidation of VOCs with NiMn/Montmorillonite: Plasma and Catalyst Considerations

Abstract

Bifunctional nanocatalyst of NiMn over alkali activated montmorillonite was prepared with different Mn contents. The prepared catalysts were examined in hybrid plasma-catalytic system for oxidation of volatile organic compounds. The prepared catalysts were characterized by XRD, FESEM, BET, FTIR and EDX analyses. FESEM pictures showed complete and uniform coverage of montmorillonite with metal oxide particles in nano scale. Increasing Mn content from 0 to 9 wt% decreased the BET surface area from 31 to 18 m2 g−1. FTIR spectra illustrated just peaks of montmorillonite and Ni or Mn related peaks were not observed even at high concentrations of Mn. The highest VOC abatement was related to NiMn/montmorillonite with 6 wt% of Mn. This catalyst in hybrid plasma-catalytic oxidation could remove 92% of benzene from polluted air with initial benzene concentration of 1000 ppm in plasma voltage of 20 kV and 9.8 kHz of frequency. While using plasma without catalyst could just remove 74% of benzene in similar conditions. NiMn/montmorillonite nanocatalyst with 6 wt% of Mn was tested at different plasma voltages (10–30 kV) and the highest VOC removal was observed at a voltage of 20 kV. Among 1–9 min residence time, the longest residence time of 9 min had supreme abatement of benzene. Study on mixture of benzene, toluene and xylene in plasma-catalytic system illustrated the highest removal for xylene and the lowest removal for benzene in plasma environment of 20 kV and 9.8 kHz.