Evaluation of Au/γ-Al2O3 nanocatalyst for plasma-catalytic decomposition of toluene.

The emission of toluene into the atmosphere can seriously affect the environmental quality and endanger human health. A dielectric barrier discharge reactor filled with a small amount of Au nanocatalysts was used to decompose toluene in He and O2 gases mixtures at room temperature and atmospheric pressure. Normally, the oxidation of toluene using Au nanocatalysts suffers from low reaction activity and facile catalyst deactivation. Herein, the effects of Au loading, calcination time and calcination temperature were systematically investigated. It was found that 0.1 wt%Au/γ-Al2O3 calcined at 300 °C for 5 h can keep an average size around 6 nm with good dispersion on γ-Al2O3 surface and display the best catalytic performance. Moreover, the influences of energy density, gas flow rate, toluene concentration and O2 concentration on toluene degradation using 0.1 wt%Au/γ-Al2O3 were evaluated. It showed the best catalytic performance of near 100% conversion for toluene degradation under the reaction conditions of the energy density was 20 J/L, the gas flow rate was 300 mL/min, the concentration of toluene was 376 mg/m3 and the oxygen content was 10%. Combining experimental results and theoretical calculations, the values of reaction constant k were 8.6 × 10-5, 3.53 × 10-5 and 3.09 × 10-5 m6/(mol*J), when O2 concentration, power or flow rate changed, respectively. Therefore, O2 concentration has the greatest effect on toluene decomposition compared to other factors in the presence of Au/γ-Al2O3.