摘要
通过醇还原和水热法制备了 4种晶型的MnO2催化剂,并考察MnO2晶型结构调控对催化剂催化氧化甲苯性能的影响.利用XRD、SEM、N2吸附-脱附、TPR、TPD等技术手段对MnO2催化剂进行结构表征与分析,并通过催化氧化甲苯的转化率评估材料对甲苯的催化性能的影响.结果表明具有α、β、γ和δ晶型结构的MnO2催化剂表现出差异较大的形貌特征和表面性质.乙二醇还原法制备的α-MnO2具有更多表面缺陷活性位点,平衡了活化表面晶格氧和Mn4+离子的协同比例,有利于催化氧化甲苯反应.甲苯转化率达50％和90％时,α-MnO2催化剂的催化氧化温度降低至210 ℃和219℃.可为过渡金属Mn系催化剂的制备及高效绿色应用提供参考.
Abstract
Four kinds of crystalline MnO2 catalysts were prepared by alcohol reduction and hydrothermal method,and the effect of MnO2 crystal structure regulation on the catalytic oxidation of toluene was investigated.The structure of MnO2 catalyst was characterized and analyzed by XRD,SEM,N2 adsorption-desorption,TPR,TPD and other technical means,and the catalytic performance of the material to toluene was evaluated by the conversion rate of toluene catalytic oxidation.The results show that MnO2 catalysts with α,β,γ and δ crystal structures show different morphological characteristics and surface properties.The α-MnO2 prepared by ethylene glycol reduction method has more surface defect active sites,which balances the synergistic ratio of activated surface lattice oxygen and Mn4+ions,and is beneficial to the catalytic oxidation of toluene.When the toluene conversion reached 50％and 90％,the catalytic oxidation temperature of α-MnO2 catalyst increased to 210 ℃ and 219 ℃.The result can provide a reference for the preparation and efficient green application of transition metal Mn-based catalysts.
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