摘要
研究同种物质不同晶相材料的催化性能对于遴选最佳的催化剂十分重要.本文利用Mn^(2+)的氧化反应制备了高纯度的不同晶相MnO_2(α,β,γ,δ相),通过苯甲醇耗氧氧化成苯甲醛的反应对其催化性能进行了评估.结果显示,在相同条件下,α-MnO_2催化该反应的产率最高.如果用表面积归一化产率,则δ-MnO_2具有最高的面积比活性,而α-MnO_2的却最低.不同晶相导致的不同微观结构决定了它们的催化性能.经过多次催化反应后,只有α-MnO_2的成分和形貌均未改变,显示出最高的催化稳定性.因此提出了一种基于Mars-van Krevelen过程的可能的反应机理.此工作可为发展有效的耗氧氧化反应催化剂提供有利支持.
Knowledge of the catalytic performances of different crystalline phases of a material is vital for the development of superior catalysts. In this study, different phases of MnO2 （（α,β,γ and δ） have been prepared by the oxidation of Mn^2＋, and their catalytic performances were evaluated using the aerobic oxidation of benzyl alcohol to benzaldehyde as a model reaction, α-MnO2 promoted the reaction to the highest yield. However, when the yields were normalized by the corresponding surface areas, δ-MnO2 exhibited the highest specific activity and a-MnO2 the lowest, indicating that the diverse microstructures resulting from the crystalline phase have a profound effect on catalytic performance, α-MnO2 showed the highest catalytic stability, resulting from its unchanged composition and morphology after use. Informed by the experimental results, a possible reaction mechanism involving the Mars-van Krevelen process was proposed. This work provides useful information for the development of effective catalysts for aerobic oxidation.
基金
supported by the National Natural Science Foundation of China (21671152,51672193 and 51420105002)
the Funding for 551 talents of Wenzhou
