Two configurations of a dielectric barrier discharge enhanced nanoparticle (CexTi1-x)O2 catalyst for the removal of low-concentration SO2

Abstract

• Reported on NTP enhanced nanoparticle (Ce x Ti 1-x )O 2 catalyst to remove low-concentration SO 2 . • The desulfurization efficiency under the ppc configuration is 30–400% higher than that of the catalyst alone, and the IPC configuration is 100% desulfurization at room temperature and pressure. • NTP increases the specific surface area of the catalyst and generates more unsaturated adsorbed oxygen and oxygen vacancies. • CCD spectrum is used to detect the discharge intermediate, and COMSOL is used to simulate the dynamic change of the intermediate in the discharge area. Removing low-concentration SO 2 present in flue gas is a worldwide problem. Herein, we introduce different technologies for coupling nonthermal plasma (NTP) with mixed CeO 2 -TiO 2 catalysts in a dielectric barrier discharge (DBD) reactor for the degradation of low-concentration SO 2 , including an in-plasma catalysis configuration (IPC) and a post-plasma catalysis configuration (PPC). Thermal catalysis at various Ce:Ti molar ratios and desulfurization efficiencies using different NTP-enhanced catalytic coupling processes were compared. We show that the SO 2 -removal efficiency in the PPC is enhanced by 20–30% by NTP, while 100% SO 2 -removal efficiency in the IPC was recorded at room temperature and atmospheric pressure, with (Ce 0.7 Ti 0.3 )O 2 exhibiting the best catalytic activity. To understand the influence of NTP on the activity of the catalytic reaction, catalytic behavior during (Ce 0.7 Ti 0.3 )O 2 thermal catalysis and during the nonthermal plasma reaction was analyzed by X-ray diffractometry, scanning electron microscopy, X-ray photoelectron spectroscopy, and N 2 physisorption experiments. The results suggest that plasma engraving increases the specific surface area of the catalyst and generates more oxygen vacancies or unsaturated active oxygen sites that promote the catalytic desulfurization reaction. Charged-coupled-device spectroscopy and COMSOL numerical simulations were used to reveal the types and transformations of reactive intermediate free radicals in the dielectric barrier discharge space. The results show that a large number of active N 2 /O 2 free radicals participate in transferring energy in the reactor, and that the first metastable state N 2 A 3 ∑ u + of N 2 is the most important excited state, as it promotes the formation and transformation of other active intermediates.