Abstract:

The catalytic activities of MnO_x-WO₃/TiO₂ catalyst in a wide temperature range were investigated for selective catalytic reduction (SCR）of NO with NH₃.It yields 80.3%—99.6% NO_x conversion and 98.7%—100% selectivity for N₂ product from 100℃ to 350℃ at GHSV 18900 h^-1.In the presence of 0.01% SO₂ and 6% H₂O at 120℃, the NO_x conversion maintains at 98.5%.At 300℃ and with 0.07% SO₂ in the reactant stream, the NO_x conversion is 99%, as high as that of the commercial V-W/TiO₂ catalyst.The steady-state kinetic study shows that O₂ plays a promoting role.When O₂ content is less than 1.5%, the NO_x conversion increases sharply with O₂ concentration.The reaction order is zero with respect to NH₃ and first with respect to NO with excess O₂ and H₂O.The active energy of Mn-W/TiO₂ calculated is 6.24 kJ·mol^-1 according to the kinetic experiments at various temperatures, much lower than other catalysts reported in the literatures.Thus Mn-W/TiO₂ is an excellent catalyst for SCR NO with NH₃.

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