文档介绍：广西师范大学硕士学位论文 摘要
Co一0/S i 02液相催化分子氧氧化二甲苯的研究
摘 要
在检索相关文献的基础上,本文综述了二甲苯的选择性催化氧化研究概况及发展趋势、氧化钻催化氧化研究进展等。鉴于直接以氧化钴为催化剂、液相催化分子氧氧化二甲苯的研究迄今未有文献报道,本研究尝试采用氧化钴、co一0/载体催化剂对二甲苯进行常压液相催化氧化研究,取得了初步的研究成果。其主要研究内容及结论如下:
:,用稀的Naott溶液作为沉淀剂,按一定比例把活性组分负载在不同载体上,一定温度下焙烧3h.
,对催化剂的催化性能进行了评价,筛选出催化性能最好的催化剂为350。/Si02(
Co—O/Si02—350,下同)。该催化剂制备简单,有良好的催化活性,特别是有相对较好的稳定性,重复使用四次后,催化活性没有较大下降。
3,用Co—O/Si02液相催化氧化二甲苯,考察了温度、时间、催化剂用量、搅拌速率等因素的影响。在不加添加剂及优化条件下,对二甲苯、间二甲苯、%、%、%,对甲苯甲酸、间甲苯甲酸、%、%、%。添加适量的溴化钠,催化活性有所提高。
,得出对二甲苯、11日J二甲苯、邻二甲苯的氧化活性顺序如下:对二甲苯>邻二甲苯>问二甲苯,且从电子效应、空问效应上分析了活性差异的原因。
5./R、XRD表征结果表明:催化剂的活性组分为氧化钴,且主要成分为 C0304。其中,、Si02的晶相外,无其它新的晶相。 Co—O/—O/Si02—350、 —350好,没有活性组分的附聚现象;随着焙烧温度升高,催化剂巾c0304的结晶度增加,从而提高了催化剂的稳定性。
,指出Co(III)为自由基引发活性中心。关键词:二甲苯;氧化钴;Co—O/Si02;催化氧化;***苯甲酸。
广西师范大学硕士学位论文 Abstracts
Aerobic Liquid Phase Oxidation of Xylene Catalyzed by Co—o/si02
Abstracts
The selective catalytic oxidation of xylene and the application of Cobalt oxide and its correlative species as oxidation catalysts are reviewed in this dissertation. Based on the judgement that the research of aerobic liquid phase oxidation of xylene catalyzed by Cobalt oxide are not developed heretoforely,we attempted to oxidize xylene using Co·O/Si02 as catalyst and molecular oxygen as oxidation reagent in the
condition of liquid Phase and atmosphere results indicated that
Co—O/Si02 was provided with better catalytic quality and main aspects
and discussion are presented as follows:
ofcatalysts:Using COCl2。6H20 as precursor ponent and dilute NaOH solution as precipitating reagent,ponent is supported on the different supports in proportion and calcined for 3 hours at certain temperature.
ofthe catalysts are measured by oxidation reaction ofp—xylene, The experiment results showed th