碳球为模板水热合成Mg-Co复合氧化物及其催化分解N2O

摘要

MgCo2O4composite oxides with spinel structure were hydrothermally prepared at 120 ℃ by using carbon sphere as template and urea as precipitant. K2CO3solution was impregnated on MgCo2O4and the K-modified catalyst was obtained. These catalysts were applied in catalytic decomposition of N2O and characterized by X-ray diffraction(XRD), nitrogen physisorption, scanning electron microscopy (SEM), temperature-programmed reduction of hydrogen (H2-TPR), temperature-programmed desorption of oxygen (O2-TPD),and X-ray photoelectron spectroscopy (XPS). Effect of catalysts preparation parameters such as mass ratio of cobalt and magnesium to carbon sphere, molar ratio of urea to metallic cations, on their catalytic activity was investigated. It is shown that the catalyst prepared with mass ratio 0.192 of cobalt and magnesium to carbon sphere,molar ratio 2 of urea to cobalt and magnesium cations, exhibits higher catalytic activity than others. Furthermore, 91% and 62% conversions of N2O could be reached over 0.02 K/MgCo2O4catalyst at 400℃ after continuous running for 50 h under the atmosphere of oxygen-alone and oxygen-steam together, respectively, revealing that K-modified MgCo2O4catalyst is stable under both reaction atmospheres.%用自制的碳球为模板剂,尿素为沉淀剂,120 ℃水热合成尖晶石型Mg-Co复合氧化物(MgCo2O4),在其表面浸渍K2CO3溶液制得K改性催化剂,用于催化分解N2O.用X射线衍射(XRD)、N2物理吸附-脱附、扫描电镜(SEM)、H2程序升温还原(H2-TPR)、O2程序升温脱附(O2-TPD)、X射线光电子能谱(XPS)等技术对催化剂进行结构表征,考察了钴镁离子/碳球的质量比、尿素/钴镁离子的物质的量比等制备参数对催化剂活性的影响.结果表明,钴镁离子/碳球的质量比为0.192、尿素/钴镁离子的物质的量比为2,制得的MgCo2O4催化剂活性较高.K改性MgCo2O4催化剂在400℃有氧无水、有氧有水条件下连续反应50 h,N2O转化率分别保持在91%和62%,稳定性较好.