Catalytic Oxidation Performances Of SO₂ By Mn-doped NiAl-hydrotalcite-derived Oxides Catalysts

In this paper,a series of physicochemical properties of NiAlhydrotalcite-derived oxides catalysts loaded with variable valence metal Mn have been prepared around the research hotspot of desulfurization in coal-fired flue gas.The performance and mechanism of the catalysts for removing SO₂ have been studied,and the effects of active oxygen species on the catalytic oxidation of SO₂ have been investigated.The main conclusions are as follows:?1?NiAl-like hydrotalcite precursors with good crystallinity and high order were successfully prepared.NiO-based composite metal oxide catalysts?Mn?NiAlO were obtained by calcination at 500?.The results show that 7%MnNiAlO catalyst have smaller particle size.The doping of Mn results in thinner lamellar structure and larger specific surface area of the catalysts.?2?Catalytic oxidation of SO₂ is closely related to oxygen vacancies,active oxygen and acid-base active sites on complex metal oxides catalysts.The doping of Mn enhances the redox ability of NiAlO catalysts,produces more oxygen vacancies,active oxygen and alkaline sites,and is easier to react with SO₂.At the same time,the number of Lewis acid sites in the catalysts was significantly increased,and Lewis acid sites were involved in the adsorption of SO₂.?3?In situ FTIR experiments show that sulfate,sulfite and SO₃ species are the main products on the surface of?Mn?NiAlO catalysts during the catalytic oxidation of SO₂.Among them,the sulfate species belong to binuclear bidentate sulfate.7%MnNiAlO catalyst has the largest adsorption peak area at the characteristic peak of binuclear bidentate sulfate,so it has better ability to oxidize and store SO₂.