• 关键词：SnO₂  Pd/SnO₂  纳米  甲酸  硝酸盐  催化还原

• 基金项目：国家科技重大专项(No.2008ZX07211-005)

• 吴以保
• 华南理工大学环境科学与工程学院 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

• 胡勇有
• 华南理工大学环境科学与工程学院 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

• 程建华
• 华南理工大学环境科学与工程学院 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

• 郭燕妮
• 华南理工大学环境科学与工程学院 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

• 摘要：采用热分解法制备了SnO₂载体,并用浸渍法制备了Pd/SnO₂催化剂.同时,采用X射线衍射仪(XRD)、透射电镜(TEM)、扫描电镜(SEM)及BET比表面积仪等对所制载体和催化剂材料进行了分析表征.结果表明,热分解法和浸渍法都能够获得纳米材料,SnO₂及Pd/SnO₂的粒径均在9～10nm左右,比表面积分别达到144.99m²·g^-1和147.36m²·g^-1.在以甲酸为还原剂的Pd/SnO₂催化还原硝酸盐体系中,在Pd与SnO₂负载比为2%～7%,反应温度为20～50℃和甲酸投加量4.0～24.0mmol·L^-1的条件下,催化活性为0.70～9.48mg·min-¹·g^-1,且催化活性随着负载比、温度和甲酸投加量的增大而增大,随着pH的升高先升后降,最佳pH为3.反应温度升高及pH降低都能够提高Pd/SnO₂的选择性.甲酸-Pd/SnO₂催化还原硝酸盐体系中还原反应的调控策略为:反应温度宜控制在40～50℃内,这样可同时获得较高的催化活性和选择性,温度过高对催化活性和选择性影响很小,温度过低则会同时降低催化活性和选择性;控制pH为3时,可以获得最大的催化活性及较好的选择性,pH升高会降低Pd/SnO₂的催化活性和选择性,pH降低会导致催化活性迅速降低,但对选择性影响不大;甲酸与硝酸盐的物质的量比宜大于4:1,此时可以有效地抑制pH的上升,同时获得较高的催化活性和选择性,甲酸与硝酸盐的物质的量比小于4:1时,会同时降低Pd/SnO₂的催化活性和选择性.

• Abstract：A Pd/SnO₂ nano-catalyst was synthesized by depositing Pb on the surface of a nano-sized SnO₂ carrier,which was prepared using fusion method.The prepared sample was characterized by XRD、TEM、SEMand BETas nano-sized particles with a size of 9 ～ 10 nm and specific surface area of 144.99 ～ 147.36 m²·g^-1.Its catalytic performance for reduction of nitrate was investigated under mild conditions,with formic acid used as reducing agent.The results showed that the catalytic activity of the Pd/SnO₂ was positively related to load ratio,temperature and initial formic acid concentration and 0.70 ～ 9.48 mg·min^-1·g^-1 was achieved at 20 ～ 50 ℃ when the loading ratio of Pd/SnO₂was 2% ～ 7%,and initial formic acid concentration was 4.0 ～ 24.0 mmol·L^-1.Additionally,the catalytic activity of Pd/SnO₂ was affected by pHand temperature.The selectivity of the Pd/SnO₂ can be enhanced at higher temperature and lower pH.The control strategies for the nitrate catalytic reduction based on formic acid-Pd/SnO₂ system are as follows:①The temperature should be controlled between 40 and 50 ℃,since higher or lower temperature are not favorable for the catalytic activity and selectivity of the system.② Maximum catalytic activity and selectivity can be achieved at pH 3.Higher pHwill reduce the catalytic activity and selectivity while lower pHrapidly decreased the catalytic activity but had little effect on the selectivity.③The molar ratio of formic acid and nitrate should be higher than 4:1,which will help control pHand promote higher catalytic activity and selectivity.

• Key words：SnO₂  Pd/SnO₂  nanoparticle  formic acid  nitrate  catalytic reduction

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