催化学报 ›› 2018, Vol. 39 ›› Issue (9): 1534-1542.DOI: 10.1016/S1872-2067(18)63082-7

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八面体四氧化三铁亚微米晶负载铂催化剂用于室温催化氧化甲醛

崔维怡a,b, 薛丹c, 谭乃迪a, 郑彬b, 贾明君b, 张文祥b   

  1. a 吉林化工学院化工清洁生产技术吉林省高校重点实验室, 吉林吉林 132022;
    b 吉林大学化学学院, 吉林省表面与界面化学重点实验室, 吉林长春 130021;
    c 西安石油大学化学化工学院, 陕西西安 710065
  • 收稿日期:2018-03-07 修回日期:2018-04-23 出版日期:2018-09-18 发布日期:2018-07-19
  • 通讯作者: 贾明君, 张文祥
  • 基金资助:

    国家自然科学基金(20973080,21473074).

Pt supported on octahedral Fe3O4 microcrystals as a catalyst for removal of formaldehyde under ambient conditions

Weiyi Cuia,b, Dan Xuec, Naidi Tana, Bin Zhengb, Mingjun Jiab, Wenxiang Zhangb   

  1. a Key Laboratory of Chemical Cleaner Production Technology of Jilin Province, Jilin Institute of Chemical Technology, Jilin 132022, Jilin, China;
    b Key Laboratory of Surface and Interface Chemistry of Jilin Province, College of Chemistry, Jilin University, Changchun 130021, Jilin, China;
    c School of Chemistry﹠Chemical Engineering, Xi'an Shiyou University, Xi'an 710065, Shaanxi, China
  • Received:2018-03-07 Revised:2018-04-23 Online:2018-09-18 Published:2018-07-19
  • Contact: 10.1016/S1872-2067(18)63082-7
  • Supported by:

    This work was supported by the National Natural Science Foundation of China (20973080, 21473074).

摘要:

空气中低浓度甲醛的治理和消除一直备受关注.在较低的反应温度下将甲醛转化为CO2和H2O的催化氧化法具有能耗低、效率高和环境友好等优点,被认为是一种最具应用发展前景的甲醛消除技术.在各种催化剂体系中,一些铁基氧化物(Fe2O3,Fe3O4或ferrihydrite)负载的Pt催化剂表现出较为优异的催化性能,能够在室温下实现甲醛的完全氧化.越来越多的研究表明,载体材料的结构及形貌是影响贵金属催化剂性能的主要因素.因此,深入研究Pt物种在不同类型铁基氧化物表面的分散情况及界面间相互作用,对理解催化剂活性中心的性质,设计制备性能更加优异的负载型贵金属催化剂具有重要科学意义.
本文采用共沉淀法一步合成出八面体Fe3O4亚微米晶负载Pt催化剂(Pt/Fe3O4),考察了不同热处理温度对催化剂催化甲醛氧化反应性能的影响.结果表明,在80℃下热处理的催化剂(Pt/Fe3O4-80)具有很高的催化活性,在室温下甲醛的转化率可接近100%.随着催化剂热处理温度的升高,催化剂活性有所降低.此外,Pt/Fe3O4催化剂还表现出良好的稳定性,经长时间存放或连续运行后催化剂的活性基本保持不变.此外,在一定湿度范围内(RH=30%-80%),水的存在能够显著提高Pt/Fe3O4催化剂的甲醛催化氧化性能.
采用各种表征技术对Pt/Fe3O4的结构、形貌、价态及氧化还原性等物理化学性质进行了研究.结果表明:采用该合成方法能够得到粒径较为均一、具有尖晶石结构和八面体形貌的Fe3O4亚微米晶,尺寸较小的Pt纳米粒子(平均2.5 nm)均匀分布在八面体Fe3O4晶体的表面,且Fe3O4载体表面还存在一定量的羟基物种.随着热处理温度的升高,催化剂表面的Pt物种和Fe物种的价态均发生明显变化.结果证实,Pt纳米粒子与Fe3O4载体间的相互作用力会随着热处理温度的升高而发生明显变化.对于性能较为优异的Pt/Fe3O4-80催化剂,Pt纳米粒子与Fe3O4载体之间存在着强度适宜的相互作用,能够产生相对较多的Pt-O-FeOx和Pt-OH-FeOx界面活性位,从而使其能够在较低的反应温度下表现出较强的活化分子氧的能力.此外,反应体系中引入的水分子能够与氧分子在界面活性位上共同活化,形成表面活性-OH物种,从而有效促进催化剂反应性能的提升.

关键词: 八面体四氧化三铁, 铂纳米粒子, 界面作用, 催化氧化, 甲醛

Abstract:

Several catalysts comprising Pt supported on octahedral Fe3O4 (Pt/Fe3O4) were prepared by a facile method involving co-precipitation followed by thermal treatment at different temperatures. A variety of characterization results revealed that this preparation process afforded highly crystalline octahedral Fe3O4 with a uniform distribution of Pt nanoparticles on its surface. The thermal-treatment temperature significantly influenced the redox properties of the Pt/Fe3O4 catalysts. All the Pt/Fe3O4 catalysts were found to be catalytically active and stable for the oxidation of low-concentration formaldehyde (HCHO) with oxygen. The catalyst prepared by thermal treatment at 80℃ (labelled Pt/Fe3O4-80) exhibited the highest catalytic activity, efficiently converting HCHO to CO2 and H2O under ambient temperature and moisture conditions. The excellent performance of Pt/Fe3O4-80 was mainly attributed to beneficial interactions between the Pt and Fe species that result in the formation a higher density of active interface sites (e.g., Pt-O-FeOx and Pt-OH-FeOx). The introduction of water vapor improves the catalytic activity of the Pt/Fe3O4 catalysts as it participates in a water-assisted dissociation process.

Key words: Octahedral Fe3O4, Pt nanoparticles, Interfacial interaction, Catalytic oxidation, Formaldehyde