整体式 Cu-ZSM-5 催化剂上 NH3 选择性催化还原 NO 活性

 采用浸渍法制备了一系列不同 Cu 含量的 Cu-ZSM-5 催化剂, 并用于 NH₃ 选择性催化还原 (SCR)NO 反应. 结果表明, 当 Cu 含量为 8%时, Cu-ZSM-5 催化剂的活性最高; 当空速为 30 000 h^–1. , 在 198~440 ^oC 反应时 NO 转化率均高于 80%, 最高可达 97%, 且空速的影响较小. 经快速水热老化后, 该催化剂活性明显优于商用 V 基催化剂. H₂O 和 SO₂ 对 Cu-ZSM-5 催化剂的 SCR 活性有所影响, 但可明显恢复. X 射线衍射和 NH3 程序升温脱附结果表明, 当 Cu-ZSM-5 中 Cu 含量为 8% 时, 进入 ZSM-5 中阳离子位的 Cu 较多, 催化剂的活性较高, 且其表面具有较多的酸中心和酸量, 从而有利于 SCR 反应.

Activity of Monolith Cu-ZSM-5 Catalyst for Selective Catalytic Reduction of NO with NH_3

A series of Cu-ZSM-5 catalyst samples with different Cu contents were prepared by an incipient wetness impregnation method and were used for selective catalytic reduction (SCR) of NO with NH3. The results showed that the Cu-ZSM-5 with 8% Cu loading had the highest catalytic activity. The conversion of NO was above 80% at 198–440 ^oC, and the highest conversion was 97% at a space velocity of 30 000 h^–1. The space velocity had less influence on the catalytic activity, and the catalytic activity temperature window was still wide at a space velocity of 60 000 h^–1. After hydrothermal aging, the catalytic activity of the Cu-ZSM-5 was significantly higher than that of the commercial V-based catalyst. The addition of H₂O and SO₂ lead to the reduced activity; however, the catalytic activity was still good. X-ray diffraction and NH3 temperature-programmed desorption results indicated that more Cu immigrated into the cation sites of ZSM-5 and the active sites of the catalyst increased when the Cu content reached 8%. Moreover, the Cu-ZSM-5 had more surface acidity centers and surface acidity, which were beneficial to SCR reaction.