Effects Of Preparation Methods On The Denitration Performance Of (Fe-Cu)/SSZ-13 Catalyst For Vehicle Exhaust

Nitrogen oxides?NO_x?in diesel exhaust could severely pollute the environment and threaten human's health.Ammonia selective catalytic reduction?NH₃-SCR?technology has been widely used for the removing of NO_x from diesel exhaust,and SCR catalysts is the corn of this technology.In recent years,the iron-modified Cu-SSZ-13 catalyst has attracted the attention of many scholars due to its excellent NH₃-SCR activity and high N₂ selectivity.The research and preparation of?Fe-Cu?/SSZ-13 catalysts mainly focus on the in-situ synthesis of Cu/SSZ-13 followed by loading with Fe²⁺/Fe³⁺and selecting Fe?NO₃?₃ as a precursor.It is known that both the preparation methods and the used precursor can affect the crystal structure and the denitration performance of catalyst.Therefore,this paper focused on the effect of ferric salt on the denitration activity of?Fe-Cu?/SSZ-13 catalysts prepared by different methods.And the content of active components,crystal structure and pore structure parameters of the catalysts were analyzed and compared by some characterization methods.The aim is to optimize the preparation parameters of?Fe-Cu?/SSZ-13 zeolite and improve its denitration performance.The main conclusions of this work are as follows:?1?The Cu/SSZ-13 catalyst prepared by in-situ hydrothermal synthesis method and then loaded with Fe²⁺/Fe³⁺by impregnation method using FeSO₄,Fe₂?SO₄?₃ and Fe?NO₃?₃ as precursor to obtain Fe-Cu/SSZ-13 catalysts.Based on the results of the NH₃-SCR denitration experiment over the synthesized catalysts,it is found that the addition of Fe could improve the activity of NO_x removing over Cu/SSZ-13 catalyst.The catalyst prepared using Fe?NO₃?₃ as precursor had a better denitration activity.And the Fe-Cu/SSZ-13 catalyst with Fe loading of 1.0 wt.%,possessed high denitration activity,stable crystal structure,and developed channel structure.?2?The SSZ-13 molecular sieve was firstly synthesized,then Cu-SSZ-13catalyst prepared by liquid-phase ion exchange and then loaded with Fe by impregnation method using FeSO₄,Fe₂?SO₄?₃ and Fe?NO₃?₃ as precursor to obtain Fe-Cu-SSZ-13 catalysts.At the same time,Cu/Fe-SSZ-13 catalysts were prepared by liquid-phase ion exchange of Cu and Fe.The denitrification activity of the catalysts without Fe obtained by above methods was superior to those with Fe,while the catalysts with Fe have better denitration activity at the high temperature.?3?The denitration activity of the optimal catalysts obtained by three kinds of preparation method was compared.It is found that Fe-Cu/SSZ-13 catalysts prepared by in-situ hydrothermal-impregnation method had a best denitration activity.This is due to higher copper loading and suitable content of copper and iron.The specific surface area is not the main reason affecting the denitrification activity of the catalyst,on the whole,the catalyst with higher surface area prepared by the same method had a better denitrification activity.