A continuous denitrification technology based on metal-organic framework without using ammonia

Ammonia is widely used as the reductant in selective catalytic reduction of nitrogen oxide. However, ammonia slip results in environmental problems. In this work, a metal-organic framework was synthesized and applied in catalytic reduction of nitric oxide without using ammonia. As a result, the catalyst removed 100% of nitric oxide at 400 °C. A two-tube reactor was designed to ensure a continuous removal and catalyst regeneration at the same time. After the catalyst lost effect in nitric-oxide removal, it was easily regenerated by a simple hydrothermal method, and reached removal rates of 90.7–99.6% for several cycles. Mass spectrometer and electron paramagnetic resonance analysis revealed that nitric oxide was effectively reduced by carbon species, including carbons, ligands, derived gases, benzene free radical, and phenoxy-type radical. After calculation, 2.4 t of the catalyst could reduce 1400 Nm3 h−1 of flue gas, when nitric oxide concentration was 250 mg Nm−3 in it. Therefore, the investigated technology is a green and sustainable denitrification strategy, which would potentially substitute typical selective catalytic reduction of nitrogen oxide in the future.