Selective Catalytic Reduction Of NO_x With NH₃ Over Metal-organic Framework MIL-47???

NO_x is one of the main pollutants in the atmosphere,and effective control of NO_xemissions plays an important role in air pollution control and environmental improvement.Ammonia selective catalytic reduction?NH₃-SCR?NOx is an effective fixed source flue gas denitration technology.At present,the widely used commercial denitration catalyst V₂O₅-WO₃/Ti O₂ has a good nitrogen oxide removal effect?300?400??in a relatively high temperature range.However,this catalyst still has some disadvantages such as low temperature?<300??activity and poor resistance to SO₂,etc.,which limits its further application.It is therefore important to design and develop a good low temperature SCR catalyst.Metal-organic framework materials?MOFs?have a tunable metal center,selectable pore size,high-density active sites,and large specific surface area,making them a great advantage in catalytic applications.This thesis explores the effect of selective catalytic reduction of nitrogen oxides and its resistance to sulfur and water by using metal-organic framework material MIL-47????MIL is Materials of Institute Lavoisier,Lavoisier Institute?.The main research results obtained are as follows:?1?MIL-47???and metal-organic framework composites MIL-47???&Co and MIL-47???&Ce doped with Co and Ce were synthesized by hydrothermal method.The above materials were applied to the NH₃-SCR catalytic reaction.?2?Selecting the metal organic framework material MIL-47???as the NH₃-SCR catalyst,the NO_x can achieve 90%conversion at 220?under the condition of 100,000h-1 space velocity,compared with the traditional V₂O₅-WO₃/Ti O₂ catalyst,T₉₀?temperature at which the NO_x conversion is 90%?is lowered by about 80?,exhibiting higher low-temperature catalytic activity.In addition,the NO_x conversion remained at around 94%within 72 h at 240?.?3?The synthetic metal organic framework material MIL-47???was tested for sulfur and water resistance.The NO_x conversion rate remained above 82%in the sulfur and water resistance tests of 5%H₂O and 50 ppm SO₂.At the same time,the conversion of NO_x gradually decreased to about 63%after 10%water and 100 ppm of SO₂,and the conversion of NO_x after the passage of water and sulfur was basically restored to the level before the passage of sulfur.It is indicated that the influence of water and sulfur coexistence on the catalyst is still mainly competitive adsorption.?4?The denitration activity and sulfur and water resistance of the metal-organic framework composites MIL-47???&Co and MIL-47???&Ce doped with Co and Ce have different performances.Among them,MIL-47???&Co has a denitration activity of more than 80%in the temperature range of 260?360?,and MIL-47???&Ce has a denitration activity of more than 80%in the temperature range of 180?260?.The denitration activity of both of them increased after the introduction of SO₂,but the water resistance of the two needs to be further improved.