Simultaneous removal of NO and SO2 through heterogeneous catalytic oxidation-absorption process using magnetic Fe2.5M0.5O4 (M = Fe, Mn, Ti and Cu) catalysts with vaporized H2O2

Fe2.5M0.5O4 (M = Mn, Ti and Cu) were investigated for the first time as the catalyst for simultaneous removal of NO and SO2 through catalytic oxidation-absorption with vaporized H2O2. The physicochemical properties of as-prepared catalysts were comprehensively characterized by XRD, SEM, TEM, BET, XPS, TPR, VSM, TG and PL analyses. Activity test results showed that SO2 can be completely removed under most conditions. However, NO removal was affected by catalyst, H2O2 consumption, reaction temperature, GHSV and coexistence gases (i.e., H2O, O2, NO and SO2). Mn, Ti and Cu doping in the magnetite can remarkably enhance NO removal. Redox pairs and oxygen vacancy of catalysts were considered as vital factors affecting OH generation. Base on the catalyst characterization and DFT calculation results, the main mechanism of Mn, Ti and Cu doping on the catalytic activity improvement was explained as follows: (a) Mn, Ti and Cu doping can increase the catalyst surface area; (b) Ti on the surface can directly promote the catalytic decomposition of H2O2; and (c) Mn and Cu doping can promote the generation of oxygen vacancy and indirectly increase the activity. Moreover, two arrangement forms of an industrial simultaneous removal system for NO, SO2 and Hg0 were proposed.