Promotion of Ag/H-BEA by Mn for Lean NO Reduction with Propane at Low Temperature

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• 作者：Hua Pan ; Qingfa Su ; Jie Chen ; Qing Ye ; Yiting Liu ; Yao Shi
• 刊名：Environmental Science & Technology
• 出版年：2009
• 出版时间：December 15, 2009
• 年：2009
• 卷：43
• 期：24
• 页码：9348-9353
• 全文大小：225K
• 年卷期：v.43,no.24(December 15, 2009)
• ISSN：1520-5851

文摘

Effects of adding manganese to Ag/H-BEA for selective catalytic reduction of NO_x with propane (C₃H₈−SCR) were investigated under a lean-burn condition. Mn addition significantly promotes the catalytic performance of Ag/H-BEA below 673 K. A Ag−Mn/H-BEA catalyst with equal metal weight of 3 wt % has the highest activity for C₃H₈−SCR among samples with a different bimetal loading. Manganese is mainly present in the 3+ and 4+ oxidation states in Ag−Mn/H-BEA catalysts. The major contributions of manganese suggested by the data presented in this paper are to catalyze the NO oxidation and stabilize silver in a dispersed Ag⁺ state. The presence of silver enforces the transformation of a certain amount of Mn³⁺ ions to Mn⁴⁺ ions. The activity of Ag−Mn/H-BEA decreases slightly at low SO₂ concentrations (0−200 ppm) but decreases significantly at high SO₂ concentrations (400−800 ppm). In the presence of 10% H₂O and 200 ppm SO₂, the inhibition of C₃H₈−SCR below 673 K is more significant than that at high temperature above 673 K. Ag−Mn/H-BEA is a promising catalyst for the removal of NO_x from diesel engine exhaust.