Mn-Co尖晶石催化氧化乙酸乙酯性能

Mn-Co spinel catalyzing oxidation of ethyl acetate

摘要:

以Mn(NO?)?、Co(NO3)2?6H2O、KMnO4和Na2CO3为原料，采用共沉淀法制备了Mn/Co不同物质的量比的Mn-Co尖晶石催化剂，利用XRD、BET、TEM、XPS、H2-TPR、O2-TPD对其进行了表征，并评价了其催化氧化乙酸乙酯的性能。结果表明，Mn/Co物质的量比的变化可影响尖晶石活性位的数量，当比n(Mn)∶n(Co)=1∶1时，制得的Mn1Co1Ox（2≤x≤3）具有最多的活性位数量，催化活性最佳〔催化剂对污染物转化率为50%时的温度T50为151 ℃、催化剂对污染物转化率为90%时的温度T90为164 ℃，反应活化能（Ea）为120.2 kJ/mol〕，这与尖晶石催化剂表面的氧空位（OV）含量、Mn4+与Co2+浓度直接相关。催化剂表面OV与金属阳离子电子交换（Co2++Mn4+?Mn3++Co3+）的协同作用构筑了高效的“OV-Mn4+-O-Co2+”活性位。

Abstract:

Mn-Co spinel catalysts with different Mn/Co molar ratios were prepared by coprecipitation method using Mn(NO?)?, Co(NO3)2?6H2O, KMnO4 and Na2CO3 as raw materials and characterized by XRD, BET, TEM, XPS, H2-TPR and O2-TPD. The catalytic oxidation of ethyl acetate by the catalysts was evaluated. The results showed that the change of Mn/Co molar ratio could change the active sites of spinel catalysts. When Mn/Co molar ratio was 1∶1, the prepared Mn1Co1Ox (2≤x≤3) had the most active sites and exhibited the best catalytic activity [Temperatures at 50% and 90% conversion of ethyl acetate (T50 and T90) were 151 ℃ and 164 ℃, respectively. And the activation energy (Ea) was 120.2 kJ/mol], which was directly related to the oxygen vacancy (OV) content, Mn4+ and Co2+ concentration on the surface of catalysts. The synergistic effects of OV and metal cation electron exchange (Co2++Mn4+?Mn3++Co3+) on the catalyst surface constructed "OV-Mn4+-O-Co2+" efficient active sites.