Simultaneous removal of SO2 and NOx by catalytic adsorption using γ-Al2O3 under the irradiation of non-thermal plasma: Competitiveness, kinetic, and equilibrium

Technologies for simultaneous removal of SO2 and NOx have been attracting great attention due to its cost-effective possibility compared to single pollutant treating counterparts. To this end, a hybrid system that integrates NTP with gamma-Al2O3 as adsorbent was developed to remove SO2 and NOx simultaneously from the exhaust gas. The adsorption capacity of gamma-Al2O3 for NOx was significantly enhanced by the presence of NTP. The overshooting of effluent concentration of NOx is due to replacement of adsorbed NOx by SO2, revealing that the competitiveness between NOx and SO2 for adsorption site. The intraparticle diffusion model fitted well the adsorption of SO2/NOx mixture under the irradiation of NTP, pointing out that the diffusion rate of target molecules may be the rate-controlling step for this process. Langmuir isotherm is suitable for describing the adsorption of NOx and SO2 on gamma-Al2O3 under the irradiation of NTP. The effects of P-d, flow rate, and bed height on the breakthrough characteristics of SO2/NOx adsorption were determined by the experiment and intraparticle diffusion model. The k(id )for both NOx and SO2 decreased with increasing P-d from 6.5 to 7.5 W and bed height from 1.0 to 2.0 cm, respectively. The possible reason for the significant enhancement of NOx adsorption capacity under the irradiation of NTP is proposed based on the experimental and theoretical data.