| 摘要 |
PURPOSE:To improve the elimination ratio of NOx by heat-treating a zeolite catalyst, which is ion-exchanged for transition metals, in a reducing gas stream containing sulphur compounds and by washing with glycol. CONSTITUTION:The metal ions in zeolite are exchanged for transition metals including Cu, Co, Cr, Ni, Fe, Mg, and Mn. The ion-exchanged zeolite catalyst 1 is heat-treated in a reducing gas stream 4 containing sulphur compounds such as hydrogen sulfide to convert the transition metal oxides existing at the positions other than the ion exchange points in the zeolite into the corresponding sulfides. The sulfides, etc., are removed by dissolving and washing with glycol. In this way, the active points in the pores, which were blocked with the sulfides, are utilized effectively so that the increased active points can contribute to the improvement in the NOx elimination ratio. |
