Study On The Performance Of Sulfur Tolerance And Regeneration And Preparation Of The Monolithic Catalyst For Scr Denitration

NOx is one of the most prominent air pollutants. It is also the main precursor of photochemistry fog. It has been a hot spot in environmental field at home and abroad to control and deal with NOX pollution. Due to high efficiency, selective and economic value, selective catalytic reduction (SCR) is the major technology for treating NOx emissions from power plant. The catalyst is the key of SCR technology. According to the catalyst could be eroded by large air flow, dust and SO₂ in the SCR technology, to improve performance of sulfur tolerance and exploit the technology to prepare monolithic catalyst become important factors for industrial application. In this paper, for different NOx SCR technology characteristics, we studied the sulfur tolerance and regeneration of Mn₁Fe_1-xCe_x/TiO₂ for the low-temperature SCR, and the technology to prepare monolithic V₂O₅-WO₃/TiO₂ ( -SiO2 ) catalyst for the high- temperature SCR also have been studied. Using MnOx as the active components, the oxides of Fe and Ce as auxiliary agent to prepare Mn₁Fe_1-xCe_x/TiO₂ catalyst for low-temperature SCR, sulfur tolerance and regeneration of Catalyst have been studied. The results showed the catalytic behavior of Mn₁Fe_0.9Ce_0.1/TiO₂ performed best, the conversion of NO was up to 100% at the temperature of 140℃. It also performed well on the sulfur tolerance, the catalytic behavior was reversible when the concentration of SO₂ was lower than 0.002vol%; when the concentration of SO₂ was more than 0.002vol%, the catalyst was poisoned irreversibly because of nitrate and sulfate formed on the surface. But the poisoned catalyst could regenerate after washed by water, the NO conversion could return to the catalytic behavior of fresh catalyst.Molding monolithic catalyst of V₂O₅-WO₃/TiO₂(-SiO2) have been studied by two methods. One is that the catalyst was squeezed by adding auxiliary agent, and the other is that the monolithic catalyst was originally prepared by impregnation method on honeycomb-shaped cordierite support. The results showed it is easy to mold catalyst by adding phosphoric acid to the finished power catalyst when the proportion of water and power is 1:2. The NO conversion could get to 90% at 320℃, it could satisfy to the catalytic activity of commercial moiding catalyst. The monolithic V₂O₅-WO₃ catalyst was originally prepared by impregnation method on honeycomb-shaped cordierite support with the coating as TiO₂(-SiO2), the best loading of V₂O₅-WO₃ was 2%, NO conversion could get to more than 90% at 340℃. Adding coating on honeycomb-shaped cordierite support could obviously improve the activity of catalyst. And the catalytic activity performed different at different space velocity. When space velocity was 30000 h^-1, NO conversion could get to 100% at 300℃. The rate of catalyst desquamation was lower than 1%, so the catalyst well combined to the honeycomb-shaped cordierite support.