Simultaneous removal of NOX and SO2 from coal-fired flue gas by catalytic oxidation-removal process with H2O2

• A novel catalytic oxidation-removal technology is proposed to simultaneously removal of SO2 and NOX.
• The oxidation removal of OH radicals is the main reaction.
• The NOX removal efficiency reaches the maximum value of 80%, and the SO2 is about 99% with this process.
• Material balances indicate that no other byproducts except NO3-, SO32- and SO42- were produced in this process.

A novel oxidation-removal process capable of removing NOX and SO2 simultaneously was proposed, which utilized the injection of OH radicals from H2O2 catalytic decomposition over hematite and assisted with a glass made ammonia-based washing tower. Oxidation experiments were conducted in a quartz reactor within an oil bath. Effects of H2O2 flow, temperature of simulated flue gas, volume ratio and preheated temperature on NOX and SO2 removal efficiencies were investigated. Results indicated that SO2 was cleaned up quite efficiently and the removal efficiency was nearly 100% under all conditions. The NOX removal efficiency depended primarily on H2O2 flow and volume ratio between purged gas and total gas, but temperature of simulated flue gas and preheated temperature had slighter influence on the NOX removal efficiency; The H2O2 flow had a significant interaction with the volume ratio. The ion products in solution were analyzed with ion chromatography (IC), and the material balances for NOX and SO2 were calculated. It showed NOX was removed in the oxidation formation of NO3-, but SO2 was mainly in the formation of SO32-. Results of material balances indicated that the main products of this oxidation-removal process were NO3-, SO32- and SO42-. The reaction pathways of removal of NOX and SO2 with this oxidation-removal process were preliminarily discussed. Meanwhile, compared with air discharge flue gas treatments, the present method had lower initial investment and operating costs.

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