SO_x Poisoning on Rh Catalysts for NO_x Selective Reduction

摘要

The inhibhiting effect of SO_2 on the activities of Rh catalysts supported on Ga-Zr-Al mixed oxides for selective reduction of NO_x with propene in the presence of excess oxygen was investigated. The catalyst treated with a mixture of SO_2 and O_2 was less active than the catalyst treated with SO_2. The preence of SO_2 (or SO_3~(2-) and SO_4~(2-) on the surfaces of both catalysts were confirmed by XPS technique. The concentration of SO_4~(2-) is significantly high, compared with the concentrations of SO_2 and SO_3~(2-), when the catalyst was treated with SO_2 and O_2, that, is, in the presence of O_2. Further, the concentration of SO_4~(2-) is as high as those of SO_2 and SO_3~(2-) for the catalyst treated with SO_2, and, therefore, these results indicated that SO_4~(2-) species on the surface mainly caused the deactivation.NO oxidation and C_3H_6 oxidation, which were regarded as initiating reactions of selective reduction of NO_x, were investigated, individually. The activity of NO oxidation was not affected by SO_2-treatment, while the activity of C_3H_6 oxidation was significantly inhibited.