Development of New Materials for NOx Removal

New materials for removal NOx from flue gases of vehicles has been studied。We have studied on the reactivity of spinel ferrite with NOx at 250~400℃.Spinel ferrite is know to be active materials for CO I D 22 ii D 2 decomposition at 300℃.It is cheap and not harmful to the environment。Oxidation of spinel ferrite below 400℃is known to form oxygen-excess spinel ferrite which is readily reduced to stoichiometric spinel ferrite by reduction with CO or H I D22文件D2，or evacuation treatment at 300℃.We found that magnetite，Ni(II)-substituted magnetite，Zn(II)-substituted magnetite and Co(II)-substituted magnetite prepared by wet method at 65℃reduced nitrogen monoxide at this temperature range by both the batch and the flow reaction methods.The reaction proceeded accompanied by the oxidation of spinel ferrite.The reaction rate of Ni(II)-substituted magnetite ferrite for NO reduction showed the highest among the prepared ferrite，and was enhanced by increasing the molar ratio of Ni-to-Fe，suggesting that Ni(II)ions promote the reduction of NO on the surface of spinel ferrite.For the preparation of further reactive spinel ferrite，we investigated on the synthesis of super-fine spinel ferrite by wet method。We succeeded in the room temperature synthesis of spinel ferrite by regulating the oxidation rate，pH value and so on。By using this method，spinel ferrite with its average diameter less than 100 nm was obtained。Still，the reaction condition for the synthesis of super-fine spinel ferrite is not knows，further investigation on this study is required。In the next stage，we are going to study on the reactivation of reacted ferrite using chemical and solid electrolyte reactions.

New materials for removal NOx from flue gases of vehicles has been studied. We have studied on the reactivity of spinel ferrite with NOx at 250 〜 400 ℃. Spinel ferrite is know to be active materials for COィイD22ィエD2 decomposition at 300 ℃. It is cheap and not harmful to the environment. Oxidation of spinel ferrite below 400 ℃ is known to form oxygen-excess spinel ferrite which is readily reduced to stoichiometric spinel ferrite by reduction with CO or HィイD22ィエD2, or evacuation treatment at 300 ℃. We found that magnetite, Ni(II)-substituted magnetite, Zn(II)-substituted magnetite and Co(II)-substituted magnetite prepared by wet method at 65 ℃ reduced nitrogen monoxide at this temperature range by both the batch and the flow reaction methods. The reaction proceeded accompanied by the oxidation of spinel ferrite. The reaction rate of Ni(II)-substituted magnetite ferrite for NO reduction showed the highest among the prepared ferrite, and was enhanced by increasing the molar ratio of Ni-to-Fe, suggesting that Ni(II) ions promote the reduction of NO on the surface of spinel ferrite. For the preparation of further reactive spinel ferrite, we investigated on the synthesis of super-fine spinel ferrite by wet method. We succeeded in the room temperature synthesis of spinel ferrite by regulating the oxidation rate, pH value and so on. By using this method, spinel ferrite with its average diameter less than 100 nm was obtained. Still, the reaction condition for the synthesis of super-fine spinel ferrite is not knows, further investigation on this study is required. In the next stage, we are going to study on the reactivation of reacted ferrite using chemical and solid electrolyte reactions.