• 关键词：磷酸硅铝分子筛  低温选择催化还原  锰物种  催化剂载体

• 基金项目：国家自然科学基金（No.51478191）；广东省省级科技计划项目（No.2014A020216003）

• 杨颖欣
• 华南理工大学环境与能源学院, 广州 510006

• 马杰文
• 华南理工大学环境与能源学院, 广州 510006

• 喻成龙
• 华南理工大学环境与能源学院, 广州 510006

• 孙梦婷
• 华南理工大学环境与能源学院, 广州 510006

• 黄碧纯
• 1. 华南理工大学环境与能源学院, 广州 510006;2. 华南理工大学工业聚集区污染控制与生态修复教育部重点实验室, 广州 510006

• 吴友明
• 广州市环境保护科学研究院, 广州 510620

• 摘要：以磷酸硅铝分子筛SAPO-5、SAPO-11和SAPO-34为载体，采用乙醇分散法制备了用于低温氨选择性还原（NH₃-SCR）NO_x的分子筛负载MnO_x催化剂.活性测试结果显示，3种分子筛催化剂均展现出优良的NH₃-SCR活性，但三者在低温区间的SCR活性存在较明显差异，其SCR活性顺序如下：MnO_x/SAPO-34 > MnO_x/SAPO-5 > MnO_x/SAPO-11.借助XRD、N₂吸附-脱附、XPS、H₂-TPR、NH₃-TPD、NH₃ FT-IR等技术对催化剂的表面活性物种及表面酸性等进行表征分析，结果表明，MnO_x主要以无定型状态分散于载体上，负载后载体的比表面积和孔体积均有所下降.XPS和H₂-TPR分析证实，不同分子筛载体上MnO_x的表面浓度与氧化态明显不同.NH₃-TPD和NH₃ FT-IR分析揭示了催化剂表面均存在Bronsted酸位和Lewis酸位，其中，Lewis酸性位对低温SCR反应起着关键作用.研究表明，催化剂的催化性能会因载体不同而存在差异，高Mn⁴⁺表面浓度和丰富的Lewis酸性位对催化剂在低温区间实现优良的催化活性尤为重要.

• Abstract：A series of MnO_x supported on SAPO-5, SAPO-11 and SAPO-34 catalysts were prepared by ethanol dispersion method and tested for selective catalytic reduction (SCR) of NO_x with NH₃ at low temperatures. All catalysts showed high NH₃-SCR activity, but their SCR activity existed obvious difference in low temperature range. The SCR performance decreased in the order of MnO_x/SAPO-34 > MnO_x/SAPO-5 > MnO_x/SAPO-11. The surface reactive species and surface acidity of the catalysts were characterized by XRD, N₂ adsorption-desorption, XPS, H₂-TPR, NH₃-TPD and NH₃ FT-IR. The results indicated that MnO_x were mainly dispersed on the supports in amorphous state, and the specific surface area and pore volume of the supports decreased after the introduction of MnO_x. XPS coupled with H₂-TPR confirmed that the amounts and valence of Mn species were quite different on different support surfaces. NH₃-TPD and NH₃ FT-IR studies revealed the presence of both Bronsted acid sites and Lewis acid sites on these catalysts, and the Lewis acid sites played a key role in low-temperature SCR reaction. Thus, it can be concluded that the good catalytic performance of catalysts at low temperature were due to the carrier properties, rich Lewis acid sites and high surface concentration of surface Mn⁴⁺ species.

• Key words：SAPO molecular sieves  low-temperature selective catalytic reduction  manganese oxide  catalyst support

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