Research On Low Temperature Catalyst For Ammonia Selective Catalytic Reduction (SCR) Of NO_x And The Design Of Solid Urea SCR System

The air pollution situation in China is very serious. NOX(nitrogen oxides) is one of theimportant causes to form acid rain, Haze, and photochemical smog. The main source ofnitrogen oxide pollution in our country include flue gas of fossil fuel emissions in industrialproduction and the vehicle exhaust emissions，Industrial emissions mainly include the fluegas of coal-fired thermal power plants and the northern-based heating coal boilers.Currently, selective catalytic reduction of NOXwith NH3in the presence of oxygen is themost widely used method in NOXremoval technology of fixed sources as power plants andindustrial boilers.TE-SCR method, which the SCR reactor is placed after desulphurizationequipment, has more prospects for its low energy consumption, long catalyst life, easyinstallation and low coal quality requirement. But the temperature of the coal flue gas（<100℃） is too low to reach the temperature window of Widely used catalysts（300℃~400℃）,like V2O5-WO3(MoO3)/TiO2.So the study of low-temperature SCRcatalyst meets the Present situation of NOXremoval technology in Chinese industrialproduction and market demand.Automobile exhaust is also a major pollution source of nitrogen oxides. Dieselvehicles have become the mainstream in transport because of its Strong powerful inproduction and construction. The major pollutants of the diesel vehicle exhaust areparticulate matters (PM) and nitrogen oxides (NOX). There are two types of controltechnology for these two exhaust pollutants; reducing the oxygen concentration and thecombustion temperature to reduce the NOXgenerating through the exhaust gas recirculation(EGR), Then use the diesel particulate filter (DPF) to remove PM. but such method reducesthe combustion efficiency of diesel; another is through optimizing the quality of the dieselengine and Improving the quality of diesel fuel to reduce the generation of PM, and thenuse selective catalytic reduction technologies (SCR) to remove NOX, this method hasdeveloped into the mainstream in NOXremoval technology due to its high combustionefficiency, excellent selectivity, and Suitable cost. Currently, the main method of generating ammonia in diesel car is thermal decomposition of ammonia solution.Ammonia solution is easy to freeze, so this method can not be applied because of the lowtemperatures in northern China. Ammonia is unstable, explosive, taking into account safetyconsiderations ammonia tank can not be placed directly in diesel car. So generatingammonia from solid matter has become one of the key topics of ammonia SCR technology.Urea is suitable as a source of ammonia Due to its cheap price, low melting point and highrate of ammonia.This paper introduce some low temperature catalyst Research of ammonia selectivecatalytic reduction (NH3-SCR) of NOXand the method of making Ammonia from Solidurea in Diesel exhaust ammonia denitration technology.（1）We use the catalysts base on Mn/TiO2to study. We make the catalysts by sol-geland impregnation methods，and test their catalytic activity in different mole ratio of Mn/Tiin different temperatures. We can find the best proportions in this way，and compare the twomethods to find which one is better.（2）The catalysts based on Fe/TiO2have high catalytic reduction effect in hightemperature which is limited by the low temperature. We dope different proportion of Mnwith the method of sol-gel to improve the low-temperature activity and the active validinterval and seek the best proportion of Mn by experiments.（3）TiO2, Al2O3both show high catalytic activity on isocyanate (HNCO) hydrolysis.This article introduce a catalyst covered method on the FeCrAl alloy，which can increasethe contact area.（4）We desire two devices in making ammonia from solid-state urea. And create oneto make Experimental test with efficient catalyst.