Simultaneous absorption of NO and SO2 by FeIIEDTA combined with Na2SO3 solution

Simultaneous removal of NOx and SO2 from flue gas using combined Na2SO3 assisted electrochemical reduction and direct electrochemical reduction.

Nitric oxide and sulfur dioxide can be removed from flue gas by scrubbing with a lime slurry containing ferrous EDTA. Tests in a 0.90m diameter column with several commercial packings gave 99 to 99.9 percent SO2 removal and 10 to 60 percent NO removal. The absorption of NO is controlled by the liquid-film resistance, and the number of transfer units varies with the square root of the ferrous EDTA concentration, the 0.4 to 0.6 power of the liquid rate, and the − 1.0 power of the gas velocity, in agreement with predictions. The height of a transfer unit for NO absorption, corrected for end effects, was 10 to 15m, about 30 times the estimated values for SO2 absorption, which is gas-film controlled. The spray tower gave lower removal rates for both gases, but the ratio of transfer units was about the same as for the packed columns.

Simultaneous removal of NO and SO2 in packed scrubbers or spray towers

Study on NO enhanced absorption using FeIIEDTA in (NH4)2SO3 solution

For wet denitrification processes nitrogen monoxide is the crucial component owing to its low water solubility. By addition of transition-metal complexes, able to form nitrosyls, the effective NO concentration in the liquid phase is enhanced. Kinetic (reaction orders and rate constants) as well as thermodynamic (stability constants) data for nitrosylation have been established. It has been found that Fe(II)-EDTA and Fe(II)-NTA react very fast to form stable NO complexes and are widely pH independent. The formation of Fe(III)-EDTA nitrosyl is found to be rapid, but the large deviation in the measured data prevents reliable evaluation. While the equilibrium constants of the Co(II)-trien and Co(II)-tetren nitrosyls are largely pH independent, the rate of formation is influenced markedly by pH. Each nitrosyl shows individual behavior towards sulfite. Fe(II)-EDTA and Fe(III)-EDTA exhibit the highest absorption capacities. The CO(II) polyamines convert the absorbed NO mainly to gaseous N2O rather than to liquid-phase products.

Absorption of nitrogen monoxide in aqueous solutions containing sulfite and transition-metal chelates such as Fe (II)-EDTA, Fe (II)-NTA, Co (II)-Trien and Co (II)-Treten

Takumi Shioya

Papers

Formation of hydroxylamidobis(sulfate) ion by the absorption of nitric oxide in aqueous solutions of sodium sulfite containing iron(II)-EDTA complex