Preparation Of Rare Earth Tailings Catalyst Modified By Cu/Ni And NH₃-SCR Denitrification Performance

The most commonly used NOx abatement control technology in industrial production is NH₃ selective catalytic reduction NOx（NH₃-SCR）technology,which has a high NOx removal efficiency and a simple equipment unit structure,which is easy to maintain and repair later.Most of the catalysts used in industrial production today are analytical pure catalysts,which are not only costly,but also complex to prepare and pollute the environment.The production and application of mineral catalysts is less polluting to the environment and can reduce the cost of catalyst production and processing.Rare earth tailings processed by Baosteel after magnetic separation also contain more rare earth elements and metal elements,such as cerium and iron,which can be fully processed and utilised as active components of catalysts.In this thesis,based on the study of rare earth tailings,the addition of transition metal elements copper and nickel was used to improve the active component of the catalyst,and the effect of the addition of a single transition metal element and the addition of both transition metals to this base on the denitrification performance of the rare earth tailings was investigated.The powder characterisation studies of the produced catalyst samples were also carried out and the experimental results showed thatThe catalysts prepared from rare earth tailings modified by the transition metal Cu can substantially improve the denitrification activity of the catalysts,and the denitrification efficiency of the modified catalysts was increased by 60%at a denitrification temperature of300°C,and the catalysts all showed good nitrogen selectivity.The specific surface area,redox capacity,surface acidic sites and crystallinity of the catalysts are enhanced by the increased amount of transition metal Cu modification,which changes the binding energy of Fe elements in the rare earth tailings and improves the activity of iron oxides,which in turn leads to an increase in denitrification efficiency of the catalysts.The catalysts prepared from the transition metal Ni modified rare earth tailings also have superior NOx removal capability,with denitrification efficiency reaching 84%at a temperature of 300°C.The specific surface area of the transition metal Ni modified catalysts was higher than that of the Cu modified catalysts,with an increase to 75.1 m²/g.Furthermore,Ni was able to interact with Fe ions in the catalysts to produce Ni Fe₂O₄ spinel phase,which greatly improved the denitrification activity of the catalysts.Simultaneous modification of two transition metals Cu and Ni in suitable proportions substantially improved the denitrification activity of the catalysts.At 2.5%Cu and 2%Ni,the catalysts reached 80%catalytic activity in the range of 250-350°C and the nitrogen selectivity was above 70%,with some improvement in denitrification performance compared to the addition of Cu elements.With 6%Ni and 5%Cu,the catalysts achieved 94%catalytic activity and over 80%nitrogen selectivity in the range of 250-350°C,which is an improvement over either Cu or Ni alone.When both Ni and Cu elements are modified in suitable proportions,a Ni Fe₂O₄ spinel structure is generated,which is beneficial to enhance the denitrification performance of the catalyst,and the Ni ions interact with Cu and Fe ions to increase the acidic sites,specific surface area and redox capacity of the catalyst surface.