不同形貌ɛ-MnO_(2)催化剂的制备及其催化燃烧甲苯性能

Preparation of ɛ-MnO_(2)with different morphologies and their catalytic combustion of toluene

采用三种不同的制备方法合成出具有不同形貌的ɛ-MnO_(2)颗粒,分别为球状ɛ-MnO_(2)、卵状ɛ-MnO_(2)和块状ɛ-MnO_(2),并考察了这三种不同形貌ɛ-MnO_(2)颗粒的催化燃烧甲苯性能。借助扫描电镜(SEM)、X射线衍射(XRD)、X射线光电子能谱(XPS)、H_(2)-程序升温还原(H_(2)-TPR)和N_(2)吸附-脱附等表征手段对其物化性质进行分析。结果表明,不同形貌的ɛ-MnO_(2)的甲苯催化燃烧性能具有明显的差异,其活性顺序为球状ɛ-MnO_(2)>块状ɛ-MnO_(2)>卵状ɛ-MnO_(2)。其中,球状ɛ-MnO_(2)具有最优异的甲苯催化燃烧性能,这与其较大的比表面积、较高的Mn^(3+)含量和较好的可还原性相关。此外,经过连续60h的稳定性测试,球状ɛ-MnO_(2)仍保持良好的催化活性。

ɛ-MnO_(2)with different morphologies,including sphere,ellipsoid and cube were prepared by three methods and their catalytic activities were investigated by catalytic combustion of toluene.The physicochemical properties of theɛ-MnO_(2)catalysts were characterized by X-ray diffraction(XRD),scanning electron microscope(SEM),N_(2) adsorption-desorption,X-ray photoelectron spectrum(XPS),and H_(2)-programmed temperature reduction(H_(2)-TPR).The results showed that the catalytic activity ofɛ-MnO_(2)depended strongly on the morphology,following the sequence of sphere>cube>ellipsoid.The superior catalytic activity of sphere-likeɛ-MnO_(2)was due to its larger surface area,higher content of Mn^(3+)and better reducibility.Moreover,the sphere-likeɛ-MnO_(2)still kept good catalytic activity after a 60h long-term test.