用于甲醛催化氧化的锰基催化剂及协同效应的影响

Catalytic Oxidation of Formaldehyde over Manganese-Based Catalysts and the Influence of Synergistic Effect

甲醛作为主要的室内空气污染气体,正在严重威胁着人类的健康。甲醛的治理引起了人们的广泛关注,其中催化氧化技术是目前最有效和环境友好的手段之一。因氧化锰结构多变和氧化能力强的特点,围绕锰基催化剂在甲醛深度氧化中应用的研究日渐成为热点。本文主要从单一组分MnOx催化剂、锰基复合氧化物催化剂、多孔材料负载MnOx催化剂以及MnOx负载贵金属催化剂四方面归纳总结了近年来锰基催化剂在甲醛氧化方面的研究进展,阐述了以Mars-van Krevelen机理为基础的甲醛催化氧化机制。在具体反应过程中,不同的表面氧物种和活性位点产生特定的中间相。重点分析了催化剂组分之间存在的协同作用对催化剂的影响,组分间的相互活化以及不同组分在多步反应中分别或依次发挥催化作用是实现锰基催化剂协同的主要方式。最后,展望了锰基催化剂在甲醛氧化反应中的未来发展方向和趋势。

Formaldehyde is one of the major indoor pollutants and has threatened the human health seriously. The treatment of formaldehyde has attracted broad attention. Catalytic oxidation is one of the most effective and environment-friendly technology. Presently, the catalytic deep oxidation of formaldehyde over manganese-based catalysts has become the research hotspot owing to the structure flexibility and good oxidation ability of manganese oxides(MnOx). The review mainly summarizes the recent progress in formaldehyde oxidation over manganese-based catalysts from four perspectives: pure MnOxcatalysts, manganese-based composite oxides, MnOx immobilization on porous material and MnOx supported noble-metal catalysts. Catalytic mechanisms are elaborated based on Mars-van Krevelen mechanism. Specified surface oxygen species and active sites in variety of catalysts produce corresponding intermediates during the catalytic oxidation of formaldehyde and consequently induce different reaction pathways. The influence of synergistic catalytic effect is emphatically discussed between catalyst components. The synergistic effect of manganese-based catalysts is achieved through one component activation by the other between two catalytic components for enhanced activity, or successional catalytic functioning of two components in catalytic reactions probably involving multi-step for enhanced activity and/or selectivity. Finally, the challenges and outlook are featured based on such catalysts in the application of HCHO removal.