卤代异羟肟酸钴(Ⅱ)配合物催化氧化二甲苯的研究  

Studies on the Catalytic Oxidation in Xylene by Cobalt(Ⅱ) Halogen-substituted Hydroxamates

作　　者：李鸿波[1] 秦川[1] 梁伍[1] 王立平[1] 郝梦安[1] 金波[1] 梁兴龙[2] 秦圣英[2] 

机构地区：[1]西南科技大学材料科学与工程学院,四川绵阳621010 [2]四川大学化学学院,四川成都610064

出　　处：《分子催化》2009年第1期62-66,共5页Journal of Molecular Catalysis(China)

基　　金：四川省科技厅项目(2006J13-143);西南科技大学引进人才项目(053115)

摘　　要：以空气为氧源,一系列卤代异羟肟酸钴(Ⅱ)配合物(CoL21～CoL29)为催化剂,研究了其液相氧化对二甲苯生成对甲苯甲酸的性能和规律,比较了配合物中引入卤原子的种类与位置对催化剂催化活性的影响,考察了氯代异羟肟酸钴(Ⅱ)配合物CoL23催化氧化不同配比的混合二甲苯的选择性.结果表明:在反应温度为110℃、催化剂浓度为1.0 mmol/L、空气流速为2.4 L/L/min的条件下,1.5 h内二氯代异羟肟酸配体的钴(Ⅱ)配合物的催化活性顺序是CoL23>CoL24>CoL27>CoL25>CoL26,1.5～4 h的催化活性顺序是CoL23>CoL27>CoL24>CoL25>CoL26.单卤代异羟肟酸配体的钴(Ⅱ)配合物催化活性顺序是CoL29>CoL22、CoL28>CoL21.当混合二甲苯中各异构体比例为5∶3∶2(对∶邻∶间)时,反应有较高的选择性,并能析出纯度达96.7%的对甲苯甲酸固体.The catalytic performance of a series of cobalt （II） halogen-substituted hydroxamates （CoL2^1- CoL^29 ） in p-xylene homogenous oxidation of p-xylene to p-toluic acid were investigated with air as oxidant. The effects of position and species of halogen in complex on the catalytic activity, the oxidation stereoselectivity of mixed xylene catalyzed by CoL2^3 were discussed. Under the reaction conditions of atmospheric pressure, reaction temperature 110 ℃, flow rate of air 2.4 L/L/min, catalyst concentration 1.0 mmol/L, the experimental results showed that the catalytic activity order of cobalt （Ⅱ） dichlorine-substituted hydroxamates was CoL2^3 〉 CoL2^4 〉 CoL2^7 〉 CoL2^5 〉 CoL2^6 in 1.5 h; but the order was CoL2^3 〉 CoL2^7 〉 CoL2^4 〉 CoL2^5 〉 CoL2^6 from 1.5 h to 4 h. The sequence of catalytic oxidation activity was CoL2^9 〉 CoL2^2, CoL2^5 〉 CoL2^1 in the different monohalogen-substituted hydroxamates. When the proportion of isomer in mixed xylene amount to 5： 3：2 （p-： o-： m-）, the reaction had high selectivity and p-toluic acid with purity of 96.7% was obtained from reaction mixture.

关 键 词：卤代异羟肟酸钴(Ⅱ) 催化氧化 (对)二甲苯 选择性 

分 类 号：O641.4[理学—物理化学] O643.3[理学—化学]