一步法合成α-MnO_(2)/β-MnO_(2)催化剂及其对甲苯催化氧化的性能研究

α-MnO2/β-MnO2 catalysts synthesized by one-pot method and their catalytic performance for the oxidation of toluene

采用水热法在不同pH条件下制备了一系列MnO_(2)基催化剂,通过XRD、SEM、N_(2)吸脱附等手段对其进行了表征,并评价了它们对甲苯催化氧化反应的催化活性。表征结果表明,不同的pH本质上改变了s反应溶液的初始H+浓度,从而影响了所得样品的结晶环境,并赋予它们不同的晶相。甲苯的催化氧化评价结果表明,催化剂的催化性能与α-MnO_(2)的含量密切相关。当pH=11时所得到的MnO_(2)-11催化剂,具有最大的比表面积和最多的缺陷结构,使其具有最佳的催化活性(T_(2)=245℃和T_(2)=256℃)和优异的循环稳定性。

A series of MnO_(2)catalysts were prepared via a hydrothermal method at different pH,characterized by XRD,SEM,N_(2)-adsorption XPS and H_(2)-TPR,and tested in the total oxidation of toluene.Different pH essentially changes the initial H^(+)concentration of the reaction solution during the synthesis process of different samples,which dramatically affects the crystallization environment of the obtained samples and gives them different crystal phase.The catalytic activity of the as-prepared MnO_(2)catalysts was evaluated by the catalytic oxidation of toluene,and the result illustrates that the catalytic performance of the catalysts is linearly dependent on the content ofα-MnO_(2).When pH=11,the obtained MnO_(2)-11 catalyst has the largest surface area and the most defect structure,which makes it have the best catalytic activity(T_(50)=245℃and T_(90)=256℃)and excellent cycling stability.