金属有机框架衍生Co_(3)O_(4)在碳烟催化燃烧中应用  

Catalytic Combustion Performance of Co_(3)O_(4) Drived from Metal-Organic Framework

作　　者：石永凯 汪炜 刘雅洁 刘嘉俊 王丽[1] 郭耘[1] Shi Yongkai;Wang Wei;Liu Yajie;Liu Jiajun;Wang Li;Guo Yun(Research Institute of Industrial Catalysis,College of Chemistry and Molecular Enginnering,East China University of Science and Technology,Shanghai 200237,China)

机构地区：[1]华东理工大学化学与分子工程学院,工业催化研究所,上海200237

出　　处：《稀有金属》2021年第8期952-960,共9页Chinese Journal of Rare Metals

基　　金：上海浦江计划项目(18PJD019)资助。

摘　　要：以金属有机框架材料(ZIF-67)为前驱体,通过热解制备了具有规则形貌的四氧化三钴(Co_(3)O_(4))催化剂,并以紧密接触状态下的碳烟催化燃烧为模型,测试了催化剂制备条件,如结晶时间和热解温度对碳烟催化燃烧性能的影响。通过X射线衍射(XRD)、场发射扫描电子显微镜(FESEM)和低温N2吸脱附实验发现400℃热解制备的Co_(3)O_(4)-400由细小纳米颗粒组成,呈现内部中空的规则多面体结构,有利于碳烟与催化剂接触;随着热解温度升高,催化剂的规则形貌被破坏,其中高温热解得到的Co_(3)O_(4)-700呈现大颗粒Co_(3)O_(4)杂乱排布。X射线光电子能谱(XPS)、氧气程序升温脱附(O_(2)-TPD)与碳烟程序升温还原(Soot-TPR)表明Co_(3)O_(4)-400表面具有较多的Co3+-O物种和氧空穴,加速了氧气的吸附与活化;而过高的热解温度导致催化剂表面Co3+-O、氧空穴含量以及活性氧物种活化速率降低。Co_(3)O_(4)-400具有较好的碳烟脱除性能,达到碳烟转化率50%所对应的温度(T50)为362℃,CO_(2)选择性为99.1%。With the rapid development of automobile industry and sustained growing quantity of cars,nitrogen oxides(NOx)and soot particles from diesel engine exhaust are harmful to health and environment. Catalytic combustion is an efficient way to reduce soot particles emission. Cobalt trioxide(Co_(3)O_(4))has excellent catalytic oxidation performance and is suitable for various catalytic oxidation reactions. Metal organic frameworks have large specific surface area,controllable pore size and metal sites with unsaturated coordination,so it can be used as the template to prepare metal oxides. Therefore,cobalt trioxide(Co_(3)O_(4))with regular morphology prepared by pyrolyzing metal-organic framework(ZIF-67)from the precursors of 2-methylimidazole and Co(NO_(3))2·6 H_(2) O. Soot combustion in tight contact mode was taken as a model reaction to investigate the effect of preparation conditions,crystallization time and pyrolysis temperature on catalytic activity. The optimum pyrolyzing temperature was very important for preparing catalysts,for it not only guaranteed the decomposition of organic ligands but also avoided the particle sintering and agglomeration,and pore structure would collapse by high temperature. With the increase in pyrolyzing temperature,the activity of soot combustion decreased accordingly. The catalysts pyrolyzing at 400 ℃(Co_(3)O_(4)-400)reached 50% soot conversion at 362 ℃ with 99.1% CO_(2) selectivity,but when the pyrolyzing temperature increased to 700 ℃(Co_(3)O_(4)-700),the temperature for 50% conversion shifted 127 ℃ to higher temperature with the CO_(2) selectivity down to 92.9%. So the optimum preparation condition for Co_(3)O_(4) was set as the mole ratio of 2-methylimidazole to Co(NO_(3))2·6 H_(2)O at4,crystallization 24 h then pyrolyzing at 400 ℃. X-ray diffraction(XRD),transmission electron microscope(TEM),field emission scanning electron microscope(FESEM),N2 adsorption-desorption and Raman spectra were used to characterize the texture structure of Co_(3)O_(4). X-ray photoelectron sp

关 键 词：ZIF-67 CO3O4 规则形貌 碳烟燃烧 

分 类 号：TQ426[化学工程]