K对Mn—Co—O的结构及氧化活性的影响

利用XRD,TPD,TFD-MS及催化氧化反应等实验技术,研究了K对Mn-Co-O的结构及氧化活性的影响。XRD结果表明,Mn-Co-O系已形成反尖晶石型的MnCo_2O_4结构;K-Mn-Co-O系中除MnCo_2O_4型结构外,还有新相KMnO_2存在。根据O_2的TPD-MS及吡啶的TPD结果,Mn-Co-O中添加适量的K能提高供氧活性和增加供氧数目,但酸中心数目减少,强度降低。K对Mn-Co—O催化剂氧化活性的影响随反应物分子结构的不同而异,对乙酸乙脂、苯甲酰氯等极性有机物的完全氧化反应,K能提高氧化活性,但对苯、正己烷等非极性有机物的完全氧化反应,K使其活性降低。

THE EFFECTS OF POTASSIUM ON THE STRUCTURE AND THE OXIDATION ACTIVITY OF Mn-Co-O CATALYST

In this paper, the effects of potassium on the structure and the catalytic activity of Mn-Co complex oxide have been studied by means of XRD, TPD, TPD-MS and deep oxidation of organic compounds XRD results showed that there is an inverse spinel structure of MnCo_2O_4 in the Mn-Co-O system and there are two phases MnCo_2O_4 and KMnO_2 in the K-Mn-Co-O system. According to the TPD profiles of oxygen and pyridine adding a proper amount of K to Mn-Co-O can increase its oxygen supplying activity and capacity, and reduce the strength and number of its surface acidic sites. The influence of K on the catalytic activity of Mn-Co-O catalyst differs with various reactants.The activity of Mn-Co-O catalyst for the complete oxidation of polar organic compounds such as ethyl acetate and benzoyl chloride was improved by the addition of K while the activity for that of nonpolar organic compounds such as benzene and n-hexane was reduced