Regeneration And SO₂ Oxidation Control Of Plate-type SCR De-nitration Catalysts

Catalyst is the key part of SCR technology, and the most widely used industrial catalyst is V2O5–WO3/TiO2. Power plant mainly from coal-fired power plants in China, so many fly ash in the flue gas, which causes the clogging in catalyst. Board type catalyst widely used because of strong anti-clogging ability, and it`s production capacity accounts for about 49.2% in China. The catalyst is highly exposed to harsh environment, such as fly ash, SOx, alkali（earth） metals and heavy metals（Hg, Pb, As, et al.）,which ultimately resulted in serious catalytic deactivation and longevity reducing of board type catalyst. Therefore, the researches on the deactivation mechanism and regeneration method of plate vanadium titanium denitration catalyst have a great application value, especially the research about the effect of Fe and As to the activity and SO<sub>2</sub> oxidation rate of board type catalyst and their regeneration research.In this work, Fe<sub>2</sub>O<sub>3</sub>-V2O5-WO3/TiO2 catalysts with different Fe/V mass ratios are prepared by impregnation method based on V2O5-WO3/TiO2 catalyst. The effect of Fe<sub>2</sub>O<sub>3</sub> on surface properties and activities of catalysts were studied.The results showed that with the increasing of the Fe<sub>2</sub>O<sub>3</sub> loading, the content of active vanadium and V4+/V5+ ratio of catalysts were decreased, while the relative-content of surface adsorption oxygen（Oα） was increased, the oxidation ability of catalysts and NO adsorption were enhanced too, which lead to denitration activity and sulfur dioxide oxidation rate of catalysts first increased then decreased. Catalyst with a Fe/V mass ratio of 3.0 showed the highest sulfur dioxide oxidation rate, 1.01%, which was more than coal-fired power plants specified value（1%）. So the mass ratio of Fe/V should be controlled with in 1.5%.The regeneration method for deactivation catalysts` Fe₂O₃ with tartrate solution（pH=6.50） was studied. The results showed that above eighty percent of Fe₂O₃ can be removed using tartrate solution（pH=6.50）, which overcomes the corrosion of stainless steel wire mesh frame and the catalyst by traditional pickling. The NO conversion of the regenerated catalyst is 92.43%, and the SO₂/SO3 converation is 0.42%.At the same time, the activity of the arsenic-poisoned catalysts was researched. The results indicated that undissolved Ca3（AsO4）2 was formed on the catalyst surface, and the content of arsenic has no effect on sulfur dioxide oxidation rate, but the NO conversion of the catalyst is decreased with the increasing of arsenic content. In this article, sulfydryl is found to be the most effective method to remove the arsenic. The oxidation ability and NO adsorption of the regenerated catalyst with sulfydryl solution are enhanced, and the NO conversion of the regenerated catalyst is 72.77%.Using the removing Fe reagen invented in this paper to regenerate the Fe-poisoned commercial catalyst of somg plants in china. The catalysts before and after regeneration are characterizd. The results indicated that Fe₂O₃ removal rate was 85.87%, the ratio of denitration activity is increased by 0.4 after regeneration, and the activity of SO₂ oxidation is reduced by 1.4. Using the removing As reagen invented in this paper to regenerate the arsenic-poisoned commercial catalyst of some plants in china. The catalysts before and after regeneration are characterizd. The results indicated that As2O3 removal rate was 46.12%, the denitration activity is 84.29% after regeneration, which is increased by 20.42%. The activity of SO₂ oxidation is 0.52% after regeneration, which is reduced by 0.21%.