硫酸盐物种对Ce-Fe-Ox催化剂脱硝性能影响的研究

Effect of sulfate species on the performance of Ce-Fe-O_(x) catalysts in the selective catalytic reduction of NO by NH_(3)

采用四种不同的方法制备了一系列含SO_(4)^(2-)改性Ce-Fe-O_(x)催化剂,并研究其NH3选择性催化还原NO_(x)的催化活性。结果表明,水热法制备的Ce-Fe-O_(x)(Fe-HT)可提高其催化性能。其优异的SCR性能与硫酸的加入有关,SO_(4)^(2-)的加入会导致CeO_(2)晶体的弱化,提高其催化活性。Fe和Ce协同作用可提高催化剂的氧化还原能力,进而提高化学吸附氧的含量、Ce^(3+)/(Ce4++Ce^(3+))和Fe^(3+)/(Fe^(3+)+Fe2+)的比例,从而提高催化性能。过量的硫酸盐会导致Fe^(3+)和Ce^(3+)的下降,降低催化性能。

A series of Ce-Fe-O_(x) catalysts containing sulfate species was prepared by four different methods including sol-gel(Fe-SG),hydrothermal(Fe-HT),co-precipitation(Fe-10)and solid state grinding synthesis(Fe-SSGS)methods.The Ce-Fe-O_(x) catalysts were used in the selective catalytic reduction(SCR)of NO_(x) by NH3 and the effect of sulfate species on the catalytic performance was investigated.The results indicate that the Fe-HT catalyst prepared by the hydrothermal method exhibits excellent performance in the NH3-SCR of NO,with a NO conversion of nearly 100%even at 250℃.The Fe-HT catalyst contains proper amount of sulfate,which can decrease the CeO_(2) crystallinity and enhance the catalytic performance in the NH3-SCR of NO.The Fe-HT catalyst has a high content of surface Ce^(3+)and Fe^(3+)and there is a synergy between the Fe and Ce species,which can improve the redox capacity and greatly increase the quantity of chemisorbed oxygen.In contrast,excessive amount of sulfate species in Fe-SSGS and Fe-SG may reduce the synergy between Fe and Ce and then impair the catalytic performance of Ce-Fe-O_(x) in NH3-SCR.