铂纳米颗粒增强MnO2纳米棒对CO和挥发性有机化合物的氧化活性

通过水热法合成了纯相的α-MnO2和δ-MnO2纳米棒,并利用溶胶固定化工艺制备了负载铂纳米颗粒的Pt/MnO2材料.通过透射电镜(TEM),X射线粉末衍射(XRD),扫描电镜(SEM),X射线光电子能谱(XPS),N2吸附-脱附和H2程序升温还原(H2-TPR)技术研究了样品的微观结构和吸附活性位,探查了CO和挥发性有机化合物(VOCs)(苯和甲苯)在催化剂上的催化发光(CTL)性质.结果表明:铂颗粒在α-MnO2和δ-MnO2载体上以高分散状态存在,负载过程不会影响α-MnO2纳米棒的晶相结构,但会导致δ-MnO2纳米棒产生结构变化.经XPS证实不是Pt与其发生了反应.α-和δ-MnO2纳米棒对CO、苯和甲苯的催化氧化都具有很高的活性,δ-MnO2的活性略高于α-MnO2相.虽然N2吸附-脱附实验结果证实Pt负载会导致MnO2纳米棒比表面积的下降,但H2-TPR结果显示Pt和MnO2之间会产生强烈的相互作用,显著增强其催化活性,且Pt/δ-MnO2活性高于Pt/α-MnO2.催化氧化发光研究表明,这四种催化剂活性顺序是α-MnO2≤δ-MnO2

Enhanced MnO2 Nanorods to CO and Volatile Organic Compounds Oxidative Activity by Platinum Nanoparticles

Pure-phase α-MnO2 and δ-MnO2 nanorods were synthesized through an easy solution-based hydrothermal method.Platinum nanoparticles supported by the obtained MnO2 nanorods were prepared by the colloid deposition process.The microstructure and adsorption activity of the obtained catalysts were researched by different techniques such as transmission electron microscopy(TEM),powder X-ray diffraction(XRD),scanning electron microscopy(SEM),X-ray photoelectron spectroscopy(XPS),N2 adsorption-desorption measurements,and H2 temperature-programmed reduction(H2-TPR).The cataluminescence(CTL) properties of CO and volatile organic compounds(VOCs),such as benzene and toluene,on the resultant catalysts were explored.The results showed that the platinum nanoparticles were well distributed in α-MnO2 and δ-MnO2.In addition,the Pt load process does not affect the crystal phase structure of the α-MnO2 nanorods,but can generate structural changes in the δ-MnO2 nanorods.The phase transformation did not the result of the reaction between the δ-MnO2 nanorods and Pt as shown in the XPS study.The α-MnO2 and δ-MnO2 nanorods showed a high catalytic oxidative activity toward CO,benzene,and toluene,and δ-MnO2 showed a higher activity than the α-MnO2 phase.Although,the Pt load led to a decrease in the surface area of the MnO2 nanorods which was confirmed by the N2 adsorption-desorption measurements,but the H2-TPR results showed that the interaction between Pt and MnO2 was intense,which significantly enhanced its catalytic activity.The Pt/δ-MnO2 nanorods exhibited a higher activity than Pt/α-MnO2.CTL research showed that the activities of the four catalysts increased in the order of α-MnO2≤δ-MnO2