Synthesis of Co-doped MnO2 catalysts with the assistance of PVP for low-temperature SCR

Abstract

MnO₂–CoO_X catalysts with different Mn/Co ratios were prepared using polyvinyl pyrrolidone (PVP) as an assistant to control the morphology and exposed crystal faces of composite oxides. The physicochemical properties of the catalysts were systematically characterized and the catalytic activity of NH₃-SCR and resistance to SO₂/H₂O were investigated. It was found that the NO conversion over Mn–Co-0.2-PVP was apparently higher compared with that over Mn–Co-X-PVP (X = 0.9, 0.8, 0.6, and 0.4). This can be interpreted in terms of exposed crystal surface (110) and enhanced adsorption of NH₃/NO, and better redox performance resulting from higher Co³⁺/Co²⁺ ratio. Furthermore, different PVP and HAc additives have different H₂O and SO₂ resistance. Mn–Co-0.2-PVP showed good resistance to H₂O and SO₂ poisoning owing to having more low-temperature (∼200 °C) NO adsorption sites, which are beneficial to promote the de-NO_X reaction and less affected by SO₂.