Non-thermal Plasma Assisted Hydrotalcite-like Compounds Approach To NO_x Removal In Diesel Engine Emissions

Diesel engine exhaust emissions, especially the emission, have caused serious harm to human health as well as the environment pollution. The existing diesel engine after-treatment technologies have the weakness of catalyst poor performance on engine cold starting, which resulting in the rise of emissions. The paper tried to combine the non-thermal plasma and the hydrotalcite-like compounds to remove the diesel engine exhaust emissions. Theoretical researches and experimental were carried out on using non-thermal plasma assisted hydrotalcite-like compounds approach to removal in diesel engine emissions.Dielectric barrier discharge is chosen to generate non-thermal plasma.The experimental device for the non-thermal plasma assisted catalytic approach to abatement has been designed, in which, the gas source was based on the simulation diesel engine exhaust gas. The experiment device could realize four gas distribution, furthermore, the gas were independent, stable and could be precisely controlled. The binding mode of non-thermal plasma and catalyst was changeable. Also, the non-thermal plasma reactor was placed in the off-type furnace, it is easy to replace catalyst and observe the reaction in the reactor. The catalyst precursors CuMg/Al were prepared through coprecipitation. X-ray diffraction analysis, thermal gravimetric analysis, scanning electron microscopy were used for the characterization of the prepared catalysts. Hydrotalcite was calcined under 450℃, and the composited metal oxide catalyst was formed. Then the author coated the catalyst on the ceramic honeycomb carrier according to the specific process conditions. Experimental were carried out using the experiment device and the prepared catalyst to remove . The result indicate that:(1) The main role of the non-thermal plasma is oxidizing the NO to 2. The non-thermal plasma must be combined with catalyst in order to achieve a better removal efficiency.(2) The CuMg/Al composited metal oxide catalyst had a better removal efficiency than its precursor. When the CuMg/Al composited metal oxide was coating on the ceramic honeycomb carrier, the removal efficiency has been further enhanced.(3) To get a higher removal efficiency and low energy loss in non-thermal plasma assisted catalyst, the voltage should between 5kV and 7.5kV. And the temperature should between 150 ℃ and 250 ℃ which is relatively low. The best removal efficiency is 26.42%. This provide a good solution ideas to the weakness of catalyst poor performance on diesel engine cold starting. In actual use, the non-thermal plasma which was combined with the ceramic catalyst had a better removal performance than the powdery catalyst.