Sustainable Conversion and Cleanup Emission of Ultralow-Concentration Nitric Oxide in Flue Gas by Functionalized Ionic Liquids in the Presence of Water and Air under Elevated Pressure

Carelessemission of nitric oxide (NO), primarily fromthe post-combustionflue gas of fossil fuel, has resulted in severe environmental pollutionand posed significant health risks to human beings. In the meantime,NO is an important intermediate in manufacturing nitric acid and nitrochemicals, where the preparation of NO has contributed to great energyconsumption. Therefore, establishing a green and low-cost denitrificationmethod to achieve the efficient conversion of NO in flue gas to nitricacid and nitro chemicals is of great significance. For this purpose,the novel strategy that applies functionalized ionic liquids to convertingultralow-concentration NO in the presence of air and water under elevatedpressure is proposed, which incorporates the positive influence ofelevated pressure on absorption and conversion of NO, efficient chemisorptionability and good catalytic performance of functionalized ionic liquids,and the elimination effect of water for nitrogen dioxide. Based onthis strategy, the high cleanup efficiency of 96.1% for 500 ppm ofNO in the realistic flue gas is achieved by the functionalized ionicliquid containing 40% water at 30 & DEG;C and 1 MPa, and nitrogenoxides concentration of the exhaust gas is only 19.6 ppm (about 28mg Nm(-3)) that meets the stringent regulation ofcleanup emission of nitrogen oxides (lower than 50 mg Nm(-3)). In addition, the presence of 750 ppm of sulfur dioxide and 5-10%water, which may deactivate the absorbents and catalysts, does notsuppress the denitrification performance of the ionic liquid. Finally,the cleanup efficiency of the ionic liquid for 500 ppm of NO maintainsat about 96.2% during 5 cycles with no traces of decomposition products.We believe that this sustainable strategy will open new prospectsfor cleanup and circular utilization of NO in industrial flue gas.