Susanne Mossin

Abstract:

The demand for end-of-pipe deNO_x technologies has driven the research for activation and conversion of nitric oxide, NO, at low temperatures compared to the traditional selective catalytic reduction of NO with ammonia. This study describes the progress made in the absorption and catalytic conversion of NO by ionic liquids. Nitrate based ionic liquids such as BMIM (butyl-methyl-imidazolium) nitrate has proven surprisingly efficient for conversion of NO_x to nitric acid using air as the oxidant.[1,2] The nitric acid is absorbed into the ionic liquid. Desorption can occur in a successive separation step forming commercial grade concentrated nitric acid and a fully regenerated absorber. Using the SILP (Supported Ionic Liquid Phase) technology the ionic liquid is impregnated onto a porous support. Alternatively, the SILP material can be extruded as monoliths and loaded into a catalyst bed for continuous NO oxidation at low temperature (< 100°C) and high humidity.[3] The technology facilitates the conversion of NO into a mixture of higher oxygenates (NO₂, HNO₂, and HNO₃) for further downstream processing or absorption. Recently[3], we have discovered that small amounts of alcohols injected into the flue gas upstream the SILP material enhances the low temperature oxidation of NO considerably, increasing the effectiveness of the catalyst. Currently we pursue the invention for gas cleaning application in collaboration with industry.