摘要
以硝酸锰和硝酸铈为锰源和铈源采用湿法浸渍法制备了不同锰铈比的γ-Al2O3负载Mn-Ce氧化物催化剂.实验结果表明,该催化剂能够有效催化以分子氧为氧化剂的醇类选择氧化反应,产物以醛或酮为主,且该催化剂能够多次循环使用而不降低活性.XRD结果表明,负载在Al2O3上的锰主要是以颗粒状β-MnO2形式存在,少量铈的加入能够促进锰的分散,使负载的β-MnO2颗粒变小,从而呈现较高的催化活性.当锰铈原子比为9∶1时,催化活性最高.焙烧温度影响催化剂的结构和组成,在较低的温度下(300℃以下)硝酸锰仅能部分分解为β-MnO2,而过高的温度(700℃)将使β-MnO2发生分解,从而降低催化活性.另外,本文还研究了氧分压、反应温度等动力学因素对催化反应性能的影响以及催化剂的稳定性.
Alumina-supported Mn-Ce oxides catalysts with different Mn-Ce atomic ratio are prepared by the incipient wetness method using manganese nitrate and cerium nitrate as the manganese sources and cerium sources. The experimental results indicated that the supported Mn-Ce oxide could efficiently catalyze the selective oxidation of alcohols, forming corresponding aldehydes or ketones as the main products. This catalyst could be recycled for several times without losing its catalytic activity. The results of XRD suggest that the manganese species supported mainly exist as β-MnO2 clusters, and the addition of cerium could disperse manganese species to form smaller β-MnO2 clusters, which are proposed for the superior catalytic activity. The highest activity could be achieved for Mn-Ce atomic ratio of 9 ： 1. The calcinations temperature is found to exert an important influence on the structures and eomponents of the Mn-Ce oxides catalysts. A low calcination temperature （〈300 ℃） only could partially decompose manganese nitrate to β-MnO2, whereas a higher temperature （700 ℃） would result in partial decomposition of β-MnO2, which would lower the catalytic activity. Moreover, effects of some kinetic factors such as O2 pressure and reaction temperature on catalytic properties as well as the stability of the catalyst have also been investigated.
出处
《河南师范大学学报（自然科学版）》
CAS
CSCD
北大核心
2008年第6期74-78,共5页
Journal of Henan Normal University(Natural Science Edition)
基金
国家自然科学基金(20673034)
河南师范大学青年科学基金(2005006)
河南省教育厅自然科学研究项目(2007150023)
关键词
锰铈氧化物
分子氧
选择氧化
醇
Mn-Ce oxide
molecular oxygen
selective oxidation
alcohol
